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Sample records for water-gas shift reaction

  1. Zeolite Membrane Reactor for Water Gas Shift Reaction for Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jerry Y.S. [Arizona State Univ., Mesa, AZ (United States)

    2013-01-29

    Gasification of biomass or heavy feedstock to produce hydrogen fuel gas using current technology is costly and energy-intensive. The technology includes water gas shift reaction in two or more reactor stages with inter-cooling to maximize conversion for a given catalyst volume. This project is focused on developing a membrane reactor for efficient conversion of water gas shift reaction to produce a hydrogen stream as a fuel and a carbon dioxide stream suitable for sequestration. The project was focused on synthesizing stable, hydrogen perm-selective MFI zeolite membranes for high temperature hydrogen separation; fabricating tubular MFI zeolite membrane reactor and stable water gas shift catalyst for membrane reactor applications, and identifying experimental conditions for water gas shift reaction in the zeolite membrane reactor that will produce a high purity hydrogen stream. The project has improved understanding of zeolite membrane synthesis, high temperature gas diffusion and separation mechanisms for zeolite membranes, synthesis and properties of sulfur resistant catalysts, fabrication and structure optimization of membrane supports, and fundamentals of coupling reaction with separation in zeolite membrane reactor for water gas shift reaction. Through the fundamental study, the research teams have developed MFI zeolite membranes with good perm-selectivity for hydrogen over carbon dioxide, carbon monoxide and water vapor, and high stability for operation in syngas mixture containing 500 part per million hydrogen sulfide at high temperatures around 500°C. The research teams also developed a sulfur resistant catalyst for water gas shift reaction. Modeling and experimental studies on the zeolite membrane reactor for water gas shift reaction have demonstrated the effective use of the zeolite membrane reactor for production of high purity hydrogen stream.

  2. Minimization of steam requirements and enhancement of water-gas shift reaction with warm gas temperature CO2 removal

    Science.gov (United States)

    Siriwardane, Ranjani V; Fisher, II, James C

    2013-12-31

    The disclosure utilizes a hydroxide sorbent for humidification and CO.sub.2 removal from a gaseous stream comprised of CO and CO.sub.2 prior to entry into a water-gas-shift reactor, in order to decrease CO.sub.2 concentration and increase H.sub.2O concentration and shift the water-gas shift reaction toward the forward reaction products CO.sub.2 and H.sub.2. The hydroxide sorbent may be utilized for absorbtion of CO.sub.2 exiting the water-gas shift reactor, producing an enriched H.sub.2 stream. The disclosure further provides for regeneration of the hydroxide sorbent at temperature approximating water-gas shift conditions, and for utilizing H.sub.2O product liberated as a result of the CO.sub.2 absorption.

  3. Advances of zeolite based membrane for hydrogen production via water gas shift reaction

    Science.gov (United States)

    Makertihartha, I. G. B. N.; Zunita, M.; Rizki, Z.; Dharmawijaya, P. T.

    2017-07-01

    Hydrogen is considered as a promising energy vector which can be obtained from various renewable sources. However, an efficient hydrogen production technology is still challenging. One technology to produce hydrogen with very high capacity with low cost is through water gas shift (WGS) reaction. Water gas shift reaction is an equilibrium reaction that produces hydrogen from syngas mixture by the introduction of steam. Conventional WGS reaction employs two or more reactors in series with inter-cooling to maximize conversion for a given volume of catalyst. Membrane reactor as new technology can cope several drawbacks of conventional reactor by removing reaction product and the reaction will favour towards product formation. Zeolite has properties namely high temperature, chemical resistant, and low price makes it suitable for membrane reactor applications. Moreover, it has been employed for years as hydrogen selective layer. This review paper is focusing on the development of membrane reactor for efficient water gas shift reaction to produce high purity hydrogen and carbon dioxide. Development of membrane reactor is discussed further related to its modification towards efficient reaction and separation from WGS reaction mixture. Moreover, zeolite framework suitable for WGS membrane reactor will be discussed more deeply.

  4. Density functional theory study on water-gas-shift reaction over molybdenum disulfide

    DEFF Research Database (Denmark)

    Shi, X. R.; Wang, Shengguang; Hu, J.

    2009-01-01

    . The pathway for water-gas-shift reaction on both terminations has been carefully studied where the most favorable reaction path precedes the redox mechanism, namely the reaction takes place as follows: CO + H2O --> CO + OH + H --> CO + O + 2H --> CO2 + H-2. The most likely reaction candidates for the formate......Density functional theory calculations have been carried out to investigate the adsorption of reaction intermediates appearing during water-gas-shift reaction at the sulfur covered MoS2 (1 0 0)surfaces, Mo-termination with 37.5% S coverage and S-termination with 50% S coverage using periodic slabs...... species HCOO formation is the surface CO2 reaction with H as a side reaction of CO2 desorption on S-termination with 50% S coverage. The formed HCOO species will react further with adsorbed hydrogen yielding H2COO followed by breaking its C-O bond to form the surface CH2O and O species....

  5. Hydrodesulphurization of Light Gas Oil using hydrogen from the Water Gas Shift Reaction

    Science.gov (United States)

    Alghamdi, Abdulaziz

    2009-12-01

    The production of clean fuel faces the challenges of high production cost and complying with stricter environmental regulations. In this research, the ability of using a novel technology of upgrading heavy oil to treat Light Gas Oil (LGO) will be investigated. The target of this project is to produce cleaner transportation fuel with much lower cost of production. Recently, a novel process for upgrading of heavy oil has been developed at University of Waterloo. It is combining the two essential processes in bitumen upgrading; emulsion breaking and hydroprocessing into one process. The water in the emulsion is used to generate in situ hydrogen from the Water Gas Shift Reaction (WGSR). This hydrogen can be used for the hydrogenation and hydrotreating reaction which includes sulfur removal instead of the expensive molecular hydrogen. This process can be carried out for the upgrading of the bitumen emulsion which would improve its quality. In this study, the hydrodesulphurization (HDS) of LGO was conducted using in situ hydrogen produced via the Water Gas Shift Reaction (WGSR). The main objective of this experimental study is to evaluate the possibility of producing clean LGO over dispersed molybdenum sulphide catalyst and to evaluate the effect of different promoters and syn-gas on the activity of the dispersed Mo catalyst. Experiments were carried out in a 300 ml Autoclave batch reactor under 600 psi (initially) at 391°C for 1 to 3 hours and different amounts of water. After the hydrotreating reaction, the gas samples were collected and the conversion of carbon monoxide to hydrogen via WGSR was determined using a refinery gas analyzer. The sulphur content in liquid sample was analyzed via X-Ray Fluorescence. Experimental results showed that using more water will enhance WGSR but at the same time inhibits the HDS reaction. It was also shown that the amount of sulfur removed depends on the reaction time. The plan is to investigate the effect of synthesis gas (syngas

  6. PdZnAl Catalysts for the Reactions of Water-Gas-Shift, Methanol Steam Reforming, and Reverse-Water-Gas-Shift

    Energy Technology Data Exchange (ETDEWEB)

    Dagle, Robert A.; Platon, Alexandru; Datye, Abhaya K.; Vohs, John M.; Wang, Yong; Palo, Daniel R.

    2008-03-07

    Pd/ZnO/Al2O3 catalysts were studied for water-gas-shift (WGS), methanol steam reforming, and reverse-water-gas-shift (RWGS) reactions. WGS activity was found to be dependent on the Pd:Zn ratio with a maximum activity obtained at approximately 0.50, which was comparable to that of a commercial Pt-based catalyst. The catalyst stability was demonstrated for 100 hours time-on-stream at a temperature of 3600C without evidence of metal sintering. WGS reaction rates were approximately 1st order with respect to CO concentration, and kinetic parameters were determined to be Ea = 58.3 kJ mol-1 and k0 = 6.1x107 min-1. During methanol steam reforming, the CO selectivities were observed to be lower than the calculated equilibrium values over a range of temperatures and steam/carbon ratios studied while the reaction rate constants were approximately of the same magnitude for both WGS and methanol steam reforming. These results indicate that although Pd/ZnO/Al2O3 are active WGS catalysts, WGS is not involved in methanol steam reforming. RWGS rate constants are on the order of about 20 times lower than that of methanol steam reforming, suggesting that RWGS reaction could be one of the sources for small amount of CO formation in methanol steam reforming.

  7. Pd based ultrathin membranes for the tritiated water gas shift reaction in the ITER breeder recovery system

    International Nuclear Information System (INIS)

    Tosti, S.; Bettinali, L.; Violante, V.; Basile, A.; Chiappetta, M.; Criscuoli, A.; Drioli, E.; Rizzelo, C.

    1998-01-01

    A mathematical model of a catalytic membrane reactor (CMR) for the water gas shift reaction has been carried out. Based on the model, a new closed loop process for the tritium removal system for the ITER test module of helium cooled pebble bed blanket concept has been studied. A CMR is the main equipment of the proposed process. The main advantages of the closed loop process are related to the absence of secondary wastes, low tritium inventories, moderate operating temperatures and pressures, low dilution of the stream to be processed by isotopic separation. As permeating membranes in the CMR ultra-thin metallic membranes of Pd and PdAg (50-70 μm thick) have been studied. A ceramic porous tube, containing the catalyst in the lumen, has been put in the metallic tube to obtain the CMR for the water gas shifting. Experimental tests, carried out both on ultra-thin membranes and CMRs for the water gas shift reaction, confirmed the behavior studied by the theoretical model and showed a long live of the membrane. (authors)

  8. Sulfur Poisoning of the Water Gas Shift Reaction on Anode Supported Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Hagen, Anke

    2013-01-01

    resistance increased both in the high and low frequency region, which indicates a strong poisoning of the water gas shift reaction and thus a lack of hydrogen fuel in addition to the poisoning of the electrochemical hydrogen oxidation. All poisoning effects are reversible under the applied operating...

  9. Role of Re in Pt-Re/TiO2 catalyst for water gas shift reaction: A mechanistic and kinetic study.

    NARCIS (Netherlands)

    Azzam, K.G.H.; Babych, Igor V.; Seshan, Kulathuiyer; Lefferts, Leonardus

    2008-01-01

    Transient kinetic studies and in situ FTIR spectroscopy were used to follow the reaction sequences that occur during water gas shift (WGS) reaction over Pt–Re/TiO2 catalyst. Results pointed to contributions of an associative formate route with redox regeneration and two classical redox routes

  10. WATER-GAS SHIFT WITH INTEGRATED HYDROGEN SEPARATION; A

    International Nuclear Information System (INIS)

    Maria Flytzani-Stephanopoulos; Jerry Meldon; Xiaomei Qi

    2001-01-01

    Optimization of the water-gas shift (WGS) reaction system for hydrogen production for fuel cells is of particular interest to the energy industry. To this end, it is desirable to couple the WGS reaction to hydrogen separation using a semi-permeable membrane, with both processes carried out at high temperature to improve reaction kinetics. Reduced equilibrium conversion of the WGS reaction at high temperatures is overcome by product H(sub 2) removal via the membrane. This project involves fundamental research and development of novel cerium oxide-based catalysts for the water-gas-shift reaction and the integration of these catalysts with Pd-alloy H(sub 2)-separation membranes supplying high purity hydrogen for fuel cell use. Conditions matching the requirements of coal gasifier-exit gas streams will be examined in the project. In the first year of the project, we prepared a series of nanostructured Cu- and Fe-containing ceria catalysts by a special gelation/precipitation technique followed by air calcination at 650 C. Each sample was characterized by ICP for elemental composition analysis, BET-N2 desorption for surface area measurement, and by temperature-programmed reduction in H(sub 2) to evaluate catalyst reducibility. Screening WGS tests with catalyst powders were conducted in a flow microreactor at temperatures in the range of 200-550 C. On the basis of both activity and stability of catalysts in simulated coal gas, and in CO(sub 2)-rich gases, a Cu-CeO(sub 2) catalyst formulation was selected for further study in this project. Details from the catalyst development and testing work are given in this report. Also in this report, we present H(sub 2) permeation data collected with unsupported flat membranes of pure Pd and Pd-alloys over a wide temperature window

  11. Catalysts synthesized by selective deposition of Fe onto Pt for the water-gas shift reaction

    Energy Technology Data Exchange (ETDEWEB)

    Aragao, Isaias Barbosa; Ro, Insoo; Liu, Yifei; Ball, Madelyn; Huber, George W.; Zanchet, Daniela; Dumesic, James A.

    2018-03-01

    FePt bimetallic catalysts with intimate contact between the two metals were synthesized by controlled surface reactions (CSR) of (cyclohexadiene)iron tricarbonyl with hydrogen-treated supported Pt nanoparticles. Adsorption of the iron precursor on a Pt/SiO2 catalyst was studied, showing that the Fe loading could be increased by performing multiple CSR cycles, and the efficiency of this process was linked to the renewal of adsorption sites by a reducing pretreatment. The catalytic activity of these bimetallic catalysts for the water gas shift reaction was improved due to promotion by iron, likely linked to H2O activation on FeOx species at or near the Pt surface, mostly in the (II) oxidation state.

  12. Reduction and Analysis of Low Temperature Shift Heterogeneous Catalyst for Water Gas Reaction in Ammonia Production

    Directory of Open Access Journals (Sweden)

    Zečević, N.

    2013-09-01

    Full Text Available In order to obtain additional quantities of hydrogen after the reforming reactions of natural gas and protect the ammonia synthesis catalyst, it is crucial to achieve and maintain maximum possible activity, selectivity and stability of the low temperature shift catalyst for conversion of water gas reaction during its lifetime. Whereas the heterogeneous catalyst comes in oxidized form, it is of the utmost importance to conduct the reduction procedure properly. The proper reduction procedure and continuous analysis of its performance would ensure the required activity, selectivity and stability throughout the catalyst’s service time. For the proper reduction procedure ofthe low temperature shift catalyst, in addition to process equipment, also necessary is a reliable and realistic system for temperature measurements, which will be effective for monitoring the exothermal temperature curves through all catalyst bed layers. For efficiency evaluation of low shift temperature catalyst reduction and its optimization, it is necessary to determine at regular time intervals the temperature approach to equilibrium and temperature profiles of individual layers by means of "S" and "die off" temperature exothermal curves. Based on the obtained data, the optimum inlet temperature could be determined, in order to maximally extend the service life of the heterogeneous catalyst as much as possible, and achieve the optimum equilibrium for conversion of the water gas. This paper presents the methodology for in situ reduction of the low temperature shift heterogeneous catalyst and the developed system for monitoring its individual layers to achieve the minimum possible content of carbon monoxide at the exit of the reactor. The developed system for temperature monitoring through heterogeneous catalyst layers provides the proper procedure for reduction and adjustment of optimum process working conditions for the catalyst by the continuous increase of reactor inlet

  13. Heat Integration of the Water-Gas Shift Reaction System for Carbon Sequestration Ready IGCC Process with Chemical Looping

    Energy Technology Data Exchange (ETDEWEB)

    Juan M. Salazara; Stephen E. Zitney; Urmila M. Diwekara

    2010-01-01

    Integrated gasification combined cycle (IGCC) technology has been considered as an important alternative for efficient power systems that can reduce fuel consumption and CO2 emissions. One of the technological schemes combines water-gas shift reaction and chemical-looping combustion as post gasification techniques in order to produce sequestration-ready CO2 and potentially reduce the size of the gas turbine. However, these schemes have not been energetically integrated and process synthesis techniques can be applied to obtain an optimal flowsheet. This work studies the heat exchange network synthesis (HENS) for the water-gas shift reaction train employing a set of alternative designs provided by Aspen energy analyzer (AEA) and combined in a process superstructure that was simulated in Aspen Plus (AP). This approach allows a rigorous evaluation of the alternative designs and their combinations avoiding all the AEA simplifications (linearized models of heat exchangers). A CAPE-OPEN compliant capability which makes use of a MINLP algorithm for sequential modular simulators was employed to obtain a heat exchange network that provided a cost of energy that was 27% lower than the base case. Highly influential parameters for the pos gasification technologies (i.e. CO/steam ratio, gasifier temperature and pressure) were calculated to obtain the minimum cost of energy while chemical looping parameters (oxidation and reduction temperature) were ensured to be satisfied.

  14. Simulation of Water Gas Shift Zeolite Membrane Reactor

    Science.gov (United States)

    Makertiharta, I. G. B. N.; Rizki, Z.; Zunita, Megawati; Dharmawijaya, P. T.

    2017-07-01

    The search of alternative energy sources keeps growing from time to time. Various alternatives have been introduced to reduce the use of fossil fuel, including hydrogen. Many pathways can be used to produce hydrogen. Among all of those, the Water Gas Shift (WGS) reaction is the most common pathway to produce high purity hydrogen. The WGS technique faces a downstream processing challenge due to the removal hydrogen from the product stream itself since it contains a mixture of hydrogen, carbon dioxide and also the excess reactants. An integrated process using zeolite membrane reactor has been introduced to improve the performance of the process by selectively separate the hydrogen whilst boosting the conversion. Furthermore, the zeolite membrane reactor can be further improved via optimizing the process condition. This paper discusses the simulation of Zeolite Membrane Water Gas Shift Reactor (ZMWGSR) with variation of process condition to achieve an optimum performance. The simulation can be simulated into two consecutive mechanisms, the reaction prior to the permeation of gases through the zeolite membrane. This paper is focused on the optimization of the process parameters (e.g. temperature, initial concentration) and also membrane properties (e.g. pore size) to achieve an optimum product specification (concentration, purity).

  15. Study of the water-gas shift reaction on Mo2C/Mo catalytic coatings for application in microstructured fuel processors

    NARCIS (Netherlands)

    Rebrov, E.V.; Kuznetsov, S.A.; Croon, de M.H.J.M.; Schouten, J.C.

    2007-01-01

    The activity and stability of two types of molybdenum carbide coatings deposited on molybdenum substrates (Mo2C/Mo) were compared in the water-gas shift reaction at 513–631 K. The activity of the Mo2C/Mo coatings obtained by carburization of preoxidized molybdenum substrates in a CH4/H2 mixture at

  16. Nano-Scale Au Supported on Carbon Materials for the Low Temperature Water Gas Shift (WGS Reaction

    Directory of Open Access Journals (Sweden)

    Paula Sánchez

    2011-12-01

    Full Text Available Au-based catalysts supported on carbon materials with different structures such as graphite (G and fishbone type carbon nanofibers (CNF-F were prepared using two different methods (impregnation and gold-sol to be tested in the water gas shift (WGS reaction. Atomic absorption spectrometry, transmission electron microscopy (TEM, temperature-programmed oxidation (TPO, X-ray diffraction (XRD, Raman spectroscopy, elemental analyses (CNH, N2 adsorption-desorption analysis, temperature-programmed reduction (TPR and temperature-programmed decomposition were employed to characterize both the supports and catalysts. Both the crystalline nature of the carbon supports and the method of gold incorporation had a strong influence on the way in which Au particles were deposited on the carbon surface. The higher crystallinity and the smaller and well dispersed Au particle size were, the higher activity of the catalysts in the WGS reaction was noted. Finally, catalytic activity showed an important dependence on the reaction temperature and steam-to-CO molar ratio.

  17. A further step toward H2 in automobile : development of an efficient bi-functional catalyst for single stage water gas shift

    NARCIS (Netherlands)

    Azzam, K.G.H.

    2008-01-01

    The suitability of polymer electrolyte fuel (PEM) cells for stationary and vehicular applications initiated research in all areas of fuel processor (i.e. reformer, water-gas-shift, preferential oxidation of CO (PROX)) catalysts for hydrogen generation. Water gas shift (WGS) reaction is an essential

  18. Application of the water gas shift reaction to fusion fuel exhaust streams

    International Nuclear Information System (INIS)

    McKay, A.M.; Cheh, C.H.; Glass, R.W.

    1983-10-01

    In a Fusion Fuel Clean Up (FCU) system, impurities will be removed from the fusion reactor exhaust and neutral beam line streams. Tritium in this impurity stream will be recovered and recycled to the fuel stream. In one flowsheet configuration of the Tritium Systems Test Assembly (TSTA), tritium is recovered from a simulated impurity stream via uranium hot metal beds and recycled to an isotope separation system. This study has shown, however, that the catalyzed water gas shift reaction, by which (H,D,T) 2 O and CO are converted to (H,D,T) 2 and CO 2 is a better method of (H,D,T) 2 O reduction than the hot metal beds. Catalytic reactors were designed, built and tested to provide data for the design of a prototype reactor to replace the hot metal beds in the FCU system. The prototype reactor contains only 10 g of catalyst and is expected to last at least 5 years. The reactor is small (1.3 cm OD x 13 cm long), operates at low temperatures (approximately 490 K) and will convert water to hydrogen, at a CO/H 2 O ratio of 1.5, with an efficiency of greater than 98 percent. Results show that the catalytic reactor is very stable even during upset conditions. Wide ranges of flow and a CO/H 2 O ratio variance from 1.3 upward have little effect on the conversion efficiency. Short term high temperature excursions do not affect the catalyst and lower temperatures will simply decrease the reaction rate resulting in lower conversions. The reactor appears to be unaffected by NO 2 , CO 2 , O 2 and N 2 in the feed stream at concentration levels expected in a fusion reactor exhaust stream

  19. WATER-GAS SHIFT KINETICS OVER IRON OXIDE CATALYSTS AT MEMBRANE REACTOR CONDITIONS; A

    International Nuclear Information System (INIS)

    Carl R.F. Lund

    2001-01-01

    This report covers the second year of a project investigating water-gas shift catalysts for use in membrane reactors. It has been established that a simple iron high temperature shift catalyst becomes ineffective in a membrane reactor because the reaction rate is severely inhibited by the build-up of the product CO(sub 2). During the past year, an improved microkinetic model for water-gas shift over iron oxide was developed. Its principal advantage over prior models is that it displays the correct asymptotic behavior at all temperatures and pressures as the composition approaches equilibrium. This model has been used to explore whether it might be possible to improve the performance of iron high temperature shift catalysts under conditions of high CO(sub 2) partial pressure. The model predicts that weakening the surface oxygen bond strength by less than 5% should lead to higher catalytic activity as well as resistance to rate inhibition at higher CO(sub 2) partial pressures. Two promoted iron high temperature shift catalysts were studied. Ceria and copper were each studied as promoters since there were indications in the literature that they might weaken the surface oxygen bond strength. Ceria was found to be ineffective as a promoter, but preliminary results with copper promoted FeCr high temperature shift catalyst show it to be much more resistant to rate inhibition by high levels of CO(sub 2). Finally, the performance of sulfided CoMo/Al(sub 2)O(sub 3) catalysts under conditions of high CO(sub 2) partial pressure was simulated using an available microkinetic model for water-gas shift over this catalyst. The model suggests that this catalyst might be quite effective in a medium temperature water-gas shift membrane reactor, provided that the membrane was resistant to the H(sub 2)S that is required in the feed

  20. Optimization of a water-gas shift reactor over a Pt/ceria/alumina monolith

    Energy Technology Data Exchange (ETDEWEB)

    Quiney, A.S.; Germani, G.; Schuurman, Y. [Institut de Recherches sur la Catalyse-CNRS, 2 Avenue A. Einstein, 69626 Villeurbanne (France)

    2006-10-06

    The water-gas shift (WGS) reaction is an important step in the purification of hydrogen for fuel cells. It lowers the carbon monoxide content and produces extra hydrogen. The constraints of automotive applications render the commercial WGS catalysts unsuitable. Pt/ceria catalysts are cited as promising catalysts for onboard applications as they are highly active and non-pyrophoric. This paper reports on a power law rate expression for a Pt/CeO{sub 2}/Al{sub 2}O{sub 3} catalyst. This rate equation is used to compare different reactor configurations for an onboard water-gas shift reactor. A one-dimensional heterogeneous model that accounts for the interfacial and intraparticle gradients has been used to optimize a dual stage adiabatic monolith reactor. (author)

  1. SiC-BASED HYDROGEN SELECTIVE MEMBRANES FOR WATER-GAS-SHIFT REACTION; F

    International Nuclear Information System (INIS)

    Paul K.T. Liu

    2001-01-01

    This technical report summarizes our activities conducted in Yr II. In Yr I we successfully demonstrated the feasibility of preparing the hydrogen selective SiC membrane with a chemical vapor deposition (CVD) technique. In addition, a SiC macroporous membrane was fabricated as a substrate candidate for the proposed SiC membrane. In Yr II we have focused on the development of a microporous SiC membrane as an intermediate layer between the substrate and the final membrane layer prepared from CVD. Powders and supported thin silicon carbide films (membranes) were prepared by a sol-gel technique using silica sol precursors as the source of silicon, and phenolic resin as the source of carbon. The powders and films were prepared by the carbothermal reduction reaction between the silica and the carbon source. The XRD analysis indicates that the powders and films consist of SiC, while the surface area measurement indicates that they contain micropores. SEM and AFM studies of the same films also validate this observation. The powders and membranes were also stable under different corrosive and harsh environments. The effects of these different treatments on the internal surface area, pore size distribution, and transport properties, were studied for both the powders and the membranes using the aforementioned techniques and XPS. Finally the SiC membrane materials are shown to have satisfactory hydrothermal stability for the proposed application. In Yr III, we will focus on the demonstration of the potential benefit using the SiC membrane developed from Yr I and II for the water-gas-shift (WGS) reaction

  2. The production of hydrogen through the use of a 77 wt% Pd 23 wt% Ag membrane water gas shift reactor

    CSIR Research Space (South Africa)

    Baloyi, Liberty N

    2016-12-01

    Full Text Available stainless steel (PSS) is evaluated for the production of hydrogen and the potential replacement of the current two-stage Water-Gas Shift (WGS) reaction by a single stage reaction. The permeability of a 20 µm Pd–Ag membrane reactor was examined at 320 °C, 380...

  3. Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification.

    Science.gov (United States)

    Castro-Dominguez, Bernardo; Mardilovich, Ivan P; Ma, Liang-Chih; Ma, Rui; Dixon, Anthony G; Kazantzis, Nikolaos K; Ma, Yi Hua

    2016-09-19

    Palladium-based catalytic membrane reactors (CMRs) effectively remove H₂ to induce higher conversions in methane steam reforming (MSR) and water-gas-shift reactions (WGS). Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H₂, CO and CO₂. After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H₂O, CO₂ and H₂. A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H₂ and induce higher methane and CO conversions while yielding ultrapure H₂ and compressed CO₂ ready for dehydration. Experimental results involving (i) a conventional packed bed reactor packed (PBR) for MSR, (ii) a PBR with five layers of two catalysts in series and (iii) a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD) model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H₂ permeance and purity, high CH₄ conversion levels and reduced CO yields.

  4. Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification

    Directory of Open Access Journals (Sweden)

    Bernardo Castro-Dominguez

    2016-09-01

    Full Text Available Palladium-based catalytic membrane reactors (CMRs effectively remove H2 to induce higher conversions in methane steam reforming (MSR and water-gas-shift reactions (WGS. Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H2, CO and CO2. After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H2O, CO2 and H2. A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H2 and induce higher methane and CO conversions while yielding ultrapure H2 and compressed CO2 ready for dehydration. Experimental results involving (i a conventional packed bed reactor packed (PBR for MSR, (ii a PBR with five layers of two catalysts in series and (iii a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H2 permeance and purity, high CH4 conversion levels and reduced CO yields.

  5. Renewable synthesis-gas-production. Do hydrocarbons in the reactant flow of the reverse water-gas shift reaction cause coke formation?

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, A.; Kern, C.; Jess, A. [Bayreuth Univ. (Germany). Dept. of Chemical Engineering

    2013-11-01

    In a two-step synthetic fuel production process based on carbon dioxide and renewable hydrogen, the best possible selectivity towards liquid hydrocarbons (Hc) shall be implemented. The process consists of a combination of the Reverse Water-Gas Shift reaction and the Fischer-Tropsch synthesis. To achieve this goal, gaseous short-chained Hc from the FTS reactor are recycled in the RWGS unit. In this paper, challenges coming up with the implementation of a recycle loop are discussed. First of all, it has to be examined whether Hc are converted under conditions present in the RWGS reactor. The coking caused by the recycle of Hc is regarded, including thermal coking in the heating zone of the reactor and catalytic coking in the catalyst bed. Coking of course is unwanted, as it deactivates the catalyst. The scope of this work is to find out to which extent and under which conditions gaseous Hc can be recycled. Therefore, experiments were carried out in both, a quartz glass reactor using a commercial Ni-catalyst at ambient pressure and in a pressurized steel reactor (without catalyst) to examine coking during the thermal decomposition of Hc. The catalytic experiments at atmospheric pressure showed that a recycle of CH{sub 4} did not cause coking up to a ratio of CH{sub 4}/CO{sub 2} below one. For these conditions, long term stability was proved. The reaction rates of the CH{sub 4} conversion were below those of the RWGS reaction. However, replacing CH{sub 4} by C{sub 3}H{sub 8} leads to thermal and catalytic coking. Catalytic coking hits the maximum level at about 700 C and decreases for higher temperatures and, thus is not regarded as a problem for the RWGS reactor. In contrast to that, thermal coking raises with higher temperatures, but it can be supressed efficiently with additional injection of H{sub 2}O, which of course shifts the equilibrium towards the undesired reactant side. (orig.)

  6. Enhancing the production of hydrogen via water-gas shift reaction using Pd-based membrane reactors

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Diogo; Chibante, Vania; Mendes, Adelio; Madeira, Luis M. [LEPAE, Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Zheng, Ju-Meng [Dutch Separation Technology Institute (DSTI), 3800 AE Amersfoort (Netherlands); Tosti, Silvano; Borgognoni, Fabio [ENEA, Unita Tecnica Fusione, C.R. ENEA Frascati, Via E. Fermi 45, Frascati (RM) I-00044 (Italy)

    2010-11-15

    In this work, it is described an experimental study regarding the performance of a Pd-Ag membrane reactor recently proposed and suitable for the production of ultra-pure hydrogen. A dense metallic permeator tube was assembled by an innovative annealing and diffusion welding technique from a commercial flat sheet membrane of Pd-Ag. A ''finger-like'' configuration of the self-supported membrane has been designed and used as a packed-bed membrane reactor (MR) for producing ultra-pure hydrogen via water-gas shift reaction (WGS). A CuO/ZnO/Al{sub 2}O{sub 3} catalyst, from REB Research and Consulting, was used for packing the WGS membrane reactor. The performance of the reactor was evaluated in terms of CO conversion and H{sub 2} recovery in a wide range of conditions: temperature from 200 C to 300 C, feed pressure from 1.0 bar to 4.0 bar, vacuum and sweep-gas modes and with a simulated reformate feed (4.70% CO, 34.78% H{sub 2}O, 28.70% H{sub 2}, 10.16% CO{sub 2} balanced in N{sub 2}). Also, the effect of the reactants feed composition was investigated and discussed. CO conversions remained in most conditions above the thermodynamic equilibrium based on feed conditions. In particular, it is worth mentioning that around 100% of CO conversion and almost complete H{sub 2} recovery was achieved when operating the MR at 300 C with a GSHV = 1200 L{sub N} kg{sub cat}{sup -1} h{sup -1}, P{sub feed} = 4 bar, P{sub perm} = 3 bar and using 1000 mL{sub N} min{sup -1} of sweep-gas. (author)

  7. Morphology-Dependent Properties of Cu/CeO2 Catalysts for the Water-Gas Shift Reaction

    Directory of Open Access Journals (Sweden)

    Zhibo Ren

    2017-02-01

    Full Text Available CeO2 nanooctahedrons, nanorods, and nanocubes were prepared by the hydrothermal method and were then used as supports of Cu-based catalysts for the water-gas shift (WGS reaction. The chemical and physical properties of these catalysts were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, N2 adsorption/desorption, UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS, hydrogen temperature-programmed reduction (H2-TPR and in situ diffuse reflectance infra-red fourier transform spectroscopy (DRIFTS techniques. Characterization results indicate that the morphology of the CeO2 supports, originating from the selective exposure of different crystal planes, has a distinct impact on the dispersion of Cu and the catalytic properties. The nanooctahedron CeO2 catalyst (Cu-CeO2-O showed the best dispersion of Cu, the largest amount of moderate copper oxide, and the strongest Cu-support interaction. Consequently, the Cu-CeO2-O catalyst exhibited the highest CO conversion at the temperature range of 150–250 °C when compared with the nanocube and nanorod Cu-CeO2 catalysts. The optimized Cu content of the Cu-CeO2-O catalysts is 10 wt % and the CO conversion reaches 91.3% at 300 °C. A distinctive profile assigned to the evolution of different types of carbonate species was observed in the 1000–1800 cm−1 region of the in situ DRIFTS spectra and a particular type of carbonate species was identified as a potential key reaction intermediate at low temperature.

  8. CHRISGAS Project. WP13: Ancillary and Novel Processes. Final Report: Separation of Hydrogen with Membranes Combined with Water Gas Shift Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Hervas, J. M.; Marono, M.; Barreiro, M. M.

    2011-05-13

    Oxygen pressurized gasification of biomass out stands as a very promising approach to obtain energy or hydrogen from renewable sources. The technical feasibility of this technology has been investigated under the scope of the VI FP CHRISGAS project, which started in September 2004 and had a duration of five and a half years. The Division of Combustion and Gasification of CIEMAT participated in this project in Work Package 13: Ancillary and novel processes, studying innovative gas separation and gas upgrading systems. Such systems include novel or available high temperature water gas shift catalysts and commercially available membranes not yet tried in this type of atmosphere. This report describes the activities carried out during the project regarding the performance of high temperature water gas shift catalysts for upgrading of synthesis gas obtained from biomass gasification, the separation of H2 with selective membranes and the combination of both processes in one by means of a catalytic membrane reactor. (Author) 20 refs.

  9. CHRISGAS Project. WP13: Ancillary and Novel Processes. Final Report: Separation of Hydrogen with Membranes Combined with Water Gas Shift Reaction

    International Nuclear Information System (INIS)

    Sanchez-Hervas, J. M.; Marono, M.; Barreiro, M. M.

    2011-01-01

    Oxygen pressurized gasification of biomass out stands as a very promising approach to obtain energy or hydrogen from renewable sources. The technical feasibility of this technology has been investigated under the scope of the VI FP CHRISGAS project, which started in September 2004 and had a duration of five and a half years. The Division of Combustion and Gasification of CIEMAT participated in this project in Work Package 13: Ancillary and novel processes, studying innovative gas separation and gas upgrading systems. Such systems include novel or available high temperature water gas shift catalysts and commercially available membranes not yet tried in this type of atmosphere. This report describes the activities carried out during the project regarding the performance of high temperature water gas shift catalysts for upgrading of synthesis gas obtained from biomass gasification, the separation of H2 with selective membranes and the combination of both processes in one by means of a catalytic membrane reactor. (Author) 20 refs.

  10. Hydrogen production from water gas shift reaction in a high gravity (Higee) environment using a rotating packed bed

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Hsin; Syu, Yu-Jhih [Department of Greenergy, National University of Tainan, Tainan 700 (China)

    2010-10-15

    Hydrogen production via the water gas shift reaction (WGSR) was investigated in a high gravity environment. A rotating packed bed (RPB) reactor containing a Cu-Zn catalyst and spinning in the range of 0-1800 rpm was used to create high centrifugal force. The reaction temperature and the steam/CO ratio ranged from 250 to 350 C and 2 to 8, respectively. A dimensionless parameter, the G number, was derived to account for the effect of centrifugal force on the enhancement of the WGSR. With the rotor speed of 1800 rpm, the induced centrifugal force acting on the reactants was as high as 234 g on average in the RPB. As a result, the CO conversion from the WGSR was increased up to 70% compared to that without rotation. This clearly revealed that the centrifugal force was conducive to hydrogen production, resulting from intensifying mass transfer and elongating the path of the reactants in the catalyst bed. From Le Chatelier's principle, a higher reaction temperature or a lower steam/CO ratio disfavors CO conversion; however, under such a situation the enhancement of the centrifugal force on hydrogen production from the WGSR tended to become more significant. Accordingly, a correlation between the enhancement of CO conversion and the G number was established. As a whole, the higher the reaction temperature and the lower the steam/CO ratio, the higher the exponent of the G number function and the better the centrifugal force on the WGSR. (author)

  11. Ambient temperature aqueous synthesis of ultrasmall copper doped ceria nanocrystals for the water gas shift and carbon monoxide oxidation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Curran, Christopher D. [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA; Lu, Li [Department of Materials Science and Engineering; Lehigh University; Bethlehem; USA; Kiely, Christopher J. [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA; Department of Materials Science and Engineering; McIntosh, Steven [Department of Chemical and Biomolecular Engineering; Lehigh University; Bethlehem; USA

    2018-01-01

    Ultra-small CuxCe1-xO2-δnanocrystals were prepared through a room temperature, aqueous synthesis method, achieving high copper doping and low water gas shift activation energy.

  12. Qualification of the ALKASORB sorbent for the sorption-enhanced water-gas shift process

    Energy Technology Data Exchange (ETDEWEB)

    Van Selow, E.R.; Cobden, P.D.; Dijk, Van H.A.J.; Walspurger, S.; Verbraeken, P.A.; Jansen, D.

    2013-07-01

    For the sorption-enhanced water-gas shift (SEWGS) process, a new sorbent material has been qualified in a reactor of 2 m length under conditions close to industrial designs. The sorbent ALKASORB is a potassium-carbonate promoted hydrotalcite-based compound. ALKASORB is shown to have many favourable properties in comparison to the reference sorbent, in particular with respect to mechanical stability. The cyclic capacity of the new compound is substantially higher than the cyclic capacity of the reference sorbent, and it allows a reduction of the steam requirement of 50%. The sorbent has demonstrated catalytic activity for the water-gas shift reaction that is sufficient to omit a separate catalyst. It is demonstrated that the sorbent remains chemically and mechanically stable during operation of at least 2000 adsorption-desorption cycles, even in the presence of H2S in the feed. H2S is shown not to influence CO2 adsorption capacity and is co-captured with the CO2. In contrast to the reference material that showed mechanical degradation during extended adsorption-desorption cycles, the new material is stable and allows to obtain carbon capture levels exceeding 95% more efficiently and more economically since the required size of the vessels will be smaller.

  13. Water-Gas Shift and CO Methanation Reactions over Ni-CeO2(111) Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    S Senanayake; J Evans; S Agnoli; L Barrio; T Chen; J Hrbek; J Rodriguez

    2011-12-31

    X-ray and ultraviolet photoelectron spectroscopies were used to study the interaction of Ni atoms with CeO{sub 2}(111) surfaces. Upon adsorption on CeO{sub 2}(111) at 300 K, nickel remains in a metallic state. Heating to elevated temperatures (500-800 K) leads to partial reduction of the ceria substrate with the formation of Ni{sup 2+} species that exists as NiO and/or Ce{sub 1-x}Ni{sub x}O{sub 2-y}. Interactions of nickel with the oxide substrate significantly reduce the density of occupied Ni 3d states near the Fermi level. The results of core-level photoemission and near-edge X-ray absorption fine structure point to weakly bound CO species on CeO{sub 2}(111) which are clearly distinguishable from the formation of chemisorbed carbonates. In the presence of Ni, a stronger interaction is observed with chemisorption of CO on the admetal. When the Ni is in contact with Ce{sup +3} cations, CO dissociates on the surface at 300 K forming NiC{sub x} compounds that may be involved in the formation of CH{sub 4} at higher temperatures. At medium and large Ni coverages (>0.3 ML), the Ni/CeO{sub 2}(111) surfaces are able to catalyze the production of methane from CO and H{sub 2}, with an activity slightly higher than that of Ni(100) or Ni(111). On the other hand, at small coverages of Ni (<0.3 ML), the Ni/CeO{sub 2}(111) surfaces exhibit a very low activity for CO methanation but are very good catalysts for the water-gas shift reaction.

  14. The effects of rare earths on activity and surface properties of Ru/γ-Al2O3 catalyst for water gas shift reaction

    Directory of Open Access Journals (Sweden)

    Laitao Luo

    2007-04-01

    Full Text Available A series of Ru-RE/γ- Al2O3 (RE = Ce, Pr, La, Sm, Tb or Gd and Ru/γ- Al2O3 catalysts were prepared by impregnation method. The influence of rare earths on the catalytic performance of Ru/γ- Al2O3 catalyst for the water gas shift reaction was studied. The catalysts were characterized by X-ray diffraction (XRD, temperature programmed reduction (TPR, temperature programmed desorption (TPD, and CO chemisorption. The results show that the addition of rare earths increases the catalytic activity of Ru based catalyst. Among these cerium is the most remarkably. The addition of cerium increases the active surface area, improves the dispersion of ruthenium, and weakens the interaction between ruthenium and the support. Cerium also affects the adsorption and reduction properties of Ru/γ-Al2O3 catalyst.

  15. Entropy Generation Minimization for Reverse Water Gas Shift (RWGS Reactors

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2018-05-01

    Full Text Available Thermal design and optimization for reverse water gas shift (RWGS reactors is particularly important to fuel synthesis in naval or commercial scenarios. The RWGS reactor with irreversibilities of heat transfer, chemical reaction and viscous flow is studied based on finite time thermodynamics or entropy generation minimization theory in this paper. The total entropy generation rate (EGR in the RWGS reactor with different boundary conditions is minimized subject to specific feed compositions and chemical conversion using optimal control theory, and the optimal configurations obtained are compared with three reference reactors with linear, constant reservoir temperature and constant heat flux operations, which are commonly used in engineering. The results show that a drastic EGR reduction of up to 23% can be achieved by optimizing the reservoir temperature profile, the inlet temperature of feed gas and the reactor length simultaneously, compared to that of the reference reactor with the linear reservoir temperature. These optimization efforts are mainly achieved by reducing the irreversibility of heat transfer. Optimal paths have subsections of relatively constant thermal force, chemical force and local EGR. A conceptual optimal design of sandwich structure for the compact modular reactor is proposed, without elaborate control tools or excessive interstage equipment. The results can provide guidelines for designing industrial RWGS reactors in naval or commercial scenarios.

  16. The Integration of a Structural Water Gas Shift Catalyst with a Vanadium Alloy Hydrogen Transport Device

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    component of conventional high temperature water gas shift iron oxide based catalysts. The catalysts contained Fe-Al-Cr-Cu-O and were synthesized by co-precipitation. A series of catalysts were prepared with 5 to 50 wt% Al2O3, with 8 wt% Cr2O3, 4 wt% CuO, and the balance Fe2O3. All of the catalysts were compared to a reference WGS catalyst (88 wt% FeOx, 8 wt% Cr2O3, and 4 wt% CuO) with no alumina. Alumina addition to conventional high temperature water gas shift catalysts at concentrations of approximately 15 wt% increased CO conversion rates and increase thermal stability. A series of high temperature water gas shift catalysts containing iron, chromia, and copper oxides were prepared with small amounts of added ceria in the system Fe-Cr-Cu-Ce-O. The catalysts were also tested kinetically under WGS conditions. 2-4 wt% ceria addition (at the expense of the iron oxide content) resulted in increased reaction rates (from 22-32% higher) compared to the reference catalyst. The project goal of a 10,000 liter per day WGS-membrane reactor was achieved by a device operating on coal derived syngas containing significant amounts of carbon monoxide and hydrogen sulfide. The membrane flux was equivalent to 52 scfh/ft2 based on a 600 psi syngas inlet pressure and corresponded to membranes costing $191 per square foot. Over 40 hours of iv exposure time to syngas has been achieved for a double membrane reactor. Two modules of the Chart reactor were tested under coal syngas for over 75 hours with a single module tested for 50 hours. The permeance values for the Chart membranes were similar to the REB reactor though total flux was reduced due to significantly thicker membranes. Overall testing of membrane reactors on coal derived syngas was over 115 hours for all reactors tested. Testing of the REB double membrane device exceeded 40 hours. Performance of the double membrane reactor has been similar to the results for the single reactor with good maintenance of flux even after these long

  17. Rate of Isotope Exchange Reaction Between Tritiated Water in a Gas Phase and Water on the Surface of Piping Materials

    International Nuclear Information System (INIS)

    Nakashio, Nobuyuki; Yamaguchi, Junya; Kobayashi, Ryusuke; Nishikawa, Masabumi

    2001-01-01

    The system effect of tritium arises from the interaction of tritium in the gas phase with water on the surface of piping materials. It has been reported that the system effect can be quantified by applying the serial reactor model to the piping system and that adsorption and isotope exchange reactions play the main roles in the trapping of tritium. The isotope exchange reaction that occurs when the chemical form of tritium in the gas phase is in the molecular form, i.e., HT or T 2 , has been named isotope exchange reaction 1, and that which occurs when tritium in the gas phase is in water form, i.e., HTO or T 2 O, has been named isotope exchange reaction 2.The rate of isotope exchange reaction 2 is experimentally quantified, and the rate is observed to be about one-third of the rate of adsorption. The trapping and release behavior of tritium from the piping surface due to isotope exchange reaction 2 is also discussed. It is certified that swamping of water vapor to process gas is effective to release tritium from the surface contaminated with tritium

  18. In Situ UV-Visible Assessment of Iron-Based High-Temperature Water-Gas Shift Catalysts Promoted with Lanthana: An Extent of Reduction Study

    Directory of Open Access Journals (Sweden)

    Basseem B. Hallac

    2018-02-01

    Full Text Available The extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt % lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe3O4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible light using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe2O3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe+2.57 for the catalyst with no lanthana and Fe+2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe+2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe+2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. The paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.

  19. The effect of catalyst support on the RWGS reaction

    International Nuclear Information System (INIS)

    Laosiripojana, N.; Sutthisripok, W.

    2004-01-01

    'Full text:' Methane steam reforming is generally applied in order to produce synthesis gas mainly consist of hydrogen and carbon monoxide for later utilization in SOFC. This reaction is always carried out with the water gas shift reaction over a catalyst at elevated temperatures resulting in some carbon dioxide production. The CO/CO2 production selectivity strongly depends on the influence of water gas shift reaction. It was observed that the reactivity of this reaction depended on the type of support material. Stabilities, activities, and kinetics of the reverse water gas shift reaction (RWGS) for commercial nickel on CeO2, ZrO2, CeO2-ZrO2, TiO2, MgO, and Al2O3 supports were studied in order to observe the influence of the support on this reaction. According to the experiment, the activities of Ni/CeO2 toward the reverse water gas shift reaction (RWGS) were very high, and reached equilibrium level at approximately 600 o C (where the conversion of CO2 was closed to 1). Other oxide supports provided lower activities toward this reaction. It was observed that the activity of Ni/Al2O3 toward this reaction was the lowest. The kinetics of this reaction was also studied. Carbon dioxide presented positive effect on the reverse water gas shift reaction. The reaction orders in carbon dioxide were observed to be positive partial value between 0-1. It slightly decreased with increasing temperature for Ni/ CeO2 and Ni/CeO2-ZrO2, whereas it seemed to be independent of the operating temperature for other materials in the range of conditions studied. Hydrogen also showed positive effect on the reverse water gas shift reaction for all materials. The reaction order in hydrogen for all materials was observed to be the positive value and less than one for the range of conditions studied. The approximate values for all catalysts were between 0.45-0.65, and seemed to be independent of the operating temperature. The estimated values of the apparent activation energy for RWGS reaction

  20. Catalytic isotope exchange reaction between deuterium gas and water pre-adsorbed on platinum/alumina

    International Nuclear Information System (INIS)

    Iida, Itsuo; Kato, Junko; Tamaru, Kenzi.

    1976-01-01

    The catalytic isotope exchange reaction between deuterium gas and the water pre-adsorbed on Pt/Al 2 O 3 was studied. At reaction temperatures above 273 K, the exchange rate was proportional to the deuterium pressure and independent of the amount of adsorbed water, which suggests that the rate determining step is the supply of deuterium from the gas phase. Its apparent activation energy was 38 kJ mol -1 . Below freezing point of water, the kinetic behaviour was different from that above freezing point. At higher deuterium pressures the rate dropped abruptly at 273 K. Below the temperature the apparent activation energy was 54 kJ mol -1 and the exchange rate depended not on the deuterium pressure but on the amount of the pre-adsorbed water. At lower pressures, however, the kinetic behaviour was the same as the above 273 K, till the rate of the supply of deuterium from the gas phase exceeded the supply of hydrogen from adsorbed water to platinum surface. These results suggest that below 273 K the supply of hydrogen is markedly retarded, the state of the adsorbed water differing from that above 273 K. It was also demonstrated that when the adsorbed water is in the state of capillary condensation, the exchange rate becomes very small. (auth.)

  1. Sorption-enhanced water gas shift reaction for high-purity hydrogen production: Application of a Na-Mg double salt-based sorbent and the divided section packing concept

    International Nuclear Information System (INIS)

    Lee, Chan Hyun; Lee, Ki Bong

    2017-01-01

    Highlights: •Na-Mg double salt-based sorbent was used for high-temperature CO 2 sorption. •Divided section packing concept was applied to the SE-WGS reaction. •High-purity H 2 was produced from the SE-WGS reaction with divided section packing. •High-purity H 2 productivity could be further enhanced by modifying packing method. -- Abstract: Hydrogen is considered a promising environmentally benign energy carrier because it has high energy density and produces no pollutants when it is converted into other types of energy. The sorption-enhanced water gas shift (SE-WGS) reaction, where the catalytic WGS reaction and byproduct CO 2 removal are carried out simultaneously in a single reactor, has received considerable attention as a novel method for high-purity hydrogen production. Since the high-purity hydrogen productivity of the SE-WGS reaction is largely dependent on the performance of the CO 2 sorbent, the development of sorbents having high CO 2 sorption capacity is crucial. Recently, a Na-Mg double salt-based sorbent has been considered for high-temperature CO 2 capture since it has been reported to have a high sorption capacity and fast sorption kinetics. In this study, the SE-WGS reaction was experimentally demonstrated using a commercial catalyst and a Na-Mg double salt-based sorbent. However, the SE-WGS reaction with a one-body hybrid solid, a physical admixture of catalyst and sorbent, showed poor reactivity and reduced CO 2 sorption uptake. As a result, a divided section packing concept was suggested as a solution. In the divided section packing method, the degree of mixing for the catalyst and sorbent in a column can be controlled by the number of sections. High-purity hydrogen (<10 ppm CO) was produced directly from the SE-WGS reaction with divided section packing, and the hydrogen productivity was further improved when the reactor column was divided into more sections and packed with more sorbent.

  2. Production of hydrogen using the combination of water-gas shift and carbonatation reaction of a CO{sub 2} absorbent; Produccion de hidrogeno mediante la combinacion de las reacciones de desplazamiento de agua y carbonatacion de un absorbente de CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo-Bretado, M. A.; Ponce-Pena, P. [Facultad de Ciencias Quimicas, UJED, Durango, Durango (Mexico)]. E-mail: miguel.escobedo@ujed.mx; Delgado-Vigil, M. D.; Salinas-Gutierrez, J. M.; Lopez Ortiz, A.; Collins-Martinez, V.H. [Centro de Investigacion en Materiales Avanzados, S.C., Chihuahua, Chihuahua (Mexico)

    2009-09-15

    The production of hydrogen by the water-gas shift (WGS) normally requires multiple catalytic reactions followed by the separation of CO{sub 2} to obtain highly pure H{sub 2}. Nevertheless, using the combination of the WGS reaction and the solid-gas reaction between CO{sub 2} and an absorbent, the production of H{sub 2} and the separation of CO{sub 2} can be accomplished in a single step AEWGS (Absorption Enhanced Water Gas Shift). This combination of reactions was studied at the laboratory scale using a quartz fixed-bed reactor. The absorbents tested were calcined dolomite (CaO*MgO) and sodium zirconate (Na{sub 2}ZrO{sub 3}) in catalyst/absorbent mixtures (cat/abs) with weight ratios of 1/1, 1/2 and 2/1, using a high-temperature catalyst from the WGS reaction, synthesized in the laboratory (Fe-Cr). All the tests used 3cm{sup 3} of cat/abs, composed of 5% CO, 15% H{sub 2}O, 10.5% He and 69.5% N{sub 2}, with a spatial velocity (SV) of 1500h-1, 600 degrees Celsius and atmospheric pressure. The catalyst presented 100% conversion of CO to CO{sub 2}, maintaining its surface area after the reaction (12 m{sup 2}/g). The results with a dry base using the cat/abs mixture of 1/2 and CaO*MgO generated 95% H{sub 2} with 5% CO-free CO{sub 2}, while with Na{sub 2}ZrO{sub 3}, the maximum concentration of H{sub 2} was 70%, with 29% CO{sub 2} and 1% of CO without reacting. The results using only CaO*MgO (as a bifunctional material) presented a maximum H{sub 2} concentration of 96% and a minimum of 4% CO{sub 2}, as well as 7% CO without reaction, which was attributed to kinetic effects. [Spanish] La produccion de hidrogeno mediante la reaccion de desplazamiento de agua WGS (Water Gas Shift), normalmente requiere de multiples reacciones cataliticas seguidas por la separacion de CO{sub 2} para obtener H{sub 2} de alta pureza. Sin embargo mediante la combinacion de la reaccion WGS con la reaccion solido-gas entre el CO{sub 2} y un absorbente provee la oportunidad de producir H2 y

  3. Chemisorption of H2O and CO2 on hydrotalcites for sorptionenhanced water-gas-shift processes

    NARCIS (Netherlands)

    Coenen, K.T.; Gallucci, F.; Cobden, P.; van Dijk, E; Hensen, E.J.M.; van Sint Annaland, M.

    2017-01-01

    Thermogravimetric analysis and breakthrough experiments in a packed bed reactor were used to validate a developed adsorption model to describe the cyclic working capacity of CO2 and H2O on a potassium-promoted hydrotalcite, a very promising adsorbent for sorption-enhanced water-gas-shift

  4. Chemisorption of H2O and CO2 on hydrotalcites for sorptionenhanced water-gas-shift processes

    NARCIS (Netherlands)

    Coenen, K.T.; Gallucci, F.; Cobden, P.; van Dijk, E.; Hensen, E.J.M.; van Sint Annaland, M.

    2016-01-01

    Thermogravimetric analysis and breakthrough experiments in a packed bed reactor were used to validate a developed adsorption model to describe the cyclic working capacity of CO¬2 and H2O on a potassium-promoted hydrotalcite, a very promising adsorbent for sorption-enhanced water-gas-shift

  5. Synthesis of Hydrocarbons from H2-Deficient Syngas in Fischer-Tropsch Synthesis over Co-Based Catalyst Coupled with Fe-Based Catalyst as Water-Gas Shift Reaction

    Directory of Open Access Journals (Sweden)

    Ting Ma

    2015-01-01

    Full Text Available The effects of metal species in an Fe-based catalyst on structural properties were investigated through the synthesis of Fe-based catalysts containing various metal species such, as Mn, Zr, and Ce. The addition of the metal species to the Fe-based catalyst resulted in high dispersions of the Fe species and high surface areas due to the formation of mesoporous voids about 2–4 nm surrounded by the catalyst particles. The metal-added Fe-based catalysts were employed together with Co-loaded beta zeolite for the synthesis of hydrocarbons from syngas with a lower H2/CO ratio of 1 than the stoichiometric H2/CO ratio of 2 for the Fischer-Tropsch synthesis (FTS. Among the catalysts, the Mn-added Fe-based catalyst exhibited a high activity for the water-gas shift (WGS reaction with a comparative durability, leading to the enhancement of the CO hydrogenation in the FTS in comparison with Co-loaded beta zeolite alone. Furthermore, the loading of Pd on the Mn-added Fe-based catalyst enhanced the catalytic durability due to the hydrogenation of carbonaceous species by the hydrogen activated over Pd.

  6. Water-gas shift (WGS) Operation of Pre-combustion CO2 Capture Pilot Plant at the Buggenum IGCC

    NARCIS (Netherlands)

    Van Dijk, H.A.J.; Damen, K.; Makkee, M.; Trapp, C.

    2014-01-01

    In the Nuon/Vattenfall CO2 Catch-up project, a pre-combustion CO2 capture pilot plant was built and operated at the Buggenum IGCC power plant, the Netherlands. The pilot consist of sweet water-gas shift, physical CO2 absorption and CO2 compression. The technology performance was verified and

  7. The energies of formation and mobilities of Cu surface species on Cu and ZnO in methanol and water gas shift atmospheres studied by DFT

    DEFF Research Database (Denmark)

    Rasmussen, Dominik Bjørn; Janssens, Ton V.W.; Temel, Burcin

    2012-01-01

    Catalysts based on copper, such as the Cu/ZnO/Al2O3 system are widely used for industrial scale methanol synthesis and the low temperature water gas shift reaction. A common characteristic of these catalysts is that they deactivate quite rapidly during operation and therefore understanding...... their deactivation by sintering is highly relevant. In this work, we study the nature of the species that are responsible for transport of the Cu metal in this catalyst type using density functional theory calculations within a chemical potential formalism. The stability and mobility of Cu–X (Cu, OH, CO, CH3O, HCOO...

  8. Atomic level study of water-gas shift catalysts via transmission electron microscopy and x-ray spectroscopy

    Science.gov (United States)

    Akatay, Mehmed Cem

    Water-gas shift (WGS), CO + H2O ⇆ CO2 + H2 (DeltaH° = -41 kJ mol -1), is an industrially important reaction for the production of high purity hydrogen. Commercial Cu/ZnO/Al2O3 catalysts are employed to accelerate this reaction, yet these catalysts suffer from certain drawbacks, including costly regeneration processes and sulfur poisoning. Extensive research is focused on developing new catalysts to replace the current technology. Supported noble metals stand out as promising candidates, yet comprise intricate nanostructures complicating the understanding of their working mechanism. In this study, the structure of the supported Pt catalysts is explored by transmission electron microscopy and X-ray spectroscopy. The effect of the supporting phase and the use of secondary metals on the reaction kinetics is investigated. Structural heterogeneities are quantified and correlated with the kinetic descriptors of the catalysts to develop a fundamental understanding of the catalytic mechanism. The effect of the reaction environment on catalyst structure is examined by in-situ techniques. This study benefitted greatly from the use of model catalysts that provide a convenient medium for the atomic level characterization of nanostructures. Based on these studies, Pt supported on iron oxide nano islands deposited on inert spherical alumina exhibited 48 times higher WGS turnover rate (normalized by the total Pt surface area) than Pt supported on bulk iron oxide. The rate of aqueous phase glycerol reforming reaction of Pt supported on multiwall carbon nanotubes (MWCNT) is promoted by co-impregnating with cobalt. The synthesis resulted in a variety of nanostructures among which Pt-Co bimetallic nanoparticles are found to be responsible for the observed promotion. The unprecedented WGS rate of Pt supported on Mo2C is explored by forming Mo 2C patches on top of MWCNTs and the rate promotion is found to be caused by the Pt-Mo bimetallic entities.

  9. Mitigation of Hydrogen Gas Generation from the Reaction of Water with Uranium Metal in K Basins Sludge

    International Nuclear Information System (INIS)

    Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

    2010-01-01

    Means to decrease the rate of hydrogen gas generation from the chemical reaction of uranium metal with water were identified by surveying the technical literature. The underlying chemistry and potential side reactions were explored by conducting 61 principal experiments. Several methods achieved significant hydrogen gas generation rate mitigation. Gas-generating side reactions from interactions of organics or sludge constituents with mitigating agents were observed. Further testing is recommended to develop deeper knowledge of the underlying chemistry and to advance the technology aturation level. Uranium metal reacts with water in K Basin sludge to form uranium hydride (UH3), uranium dioxide or uraninite (UO2), and diatomic hydrogen (H2). Mechanistic studies show that hydrogen radicals (H·) and UH3 serve as intermediates in the reaction of uranium metal with water to produce H2 and UO2. Because H2 is flammable, its release into the gas phase above K Basin sludge during sludge storage, processing, immobilization, shipment, and disposal is a concern to the safety of those operations. Findings from the technical literature and from experimental investigations with simple chemical systems (including uranium metal in water), in the presence of individual sludge simulant components, with complete sludge simulants, and with actual K Basin sludge are presented in this report. Based on the literature review and intermediate lab test results, sodium nitrate, sodium nitrite, Nochar Acid Bond N960, disodium hydrogen phosphate, and hexavalent uranium [U(VI)] were tested for their effects in decreasing the rate of hydrogen generation from the reaction of uranium metal with water. Nitrate and nitrite each were effective, decreasing hydrogen generation rates in actual sludge by factors of about 100 to 1000 when used at 0.5 molar (M) concentrations. Higher attenuation factors were achieved in tests with aqueous solutions alone. Nochar N960, a water sorbent, decreased hydrogen

  10. Mitigation of Hydrogen Gas Generation from the Reaction of Water with Uranium Metal in K Basins Sludge

    Energy Technology Data Exchange (ETDEWEB)

    Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

    2010-01-29

    Means to decrease the rate of hydrogen gas generation from the chemical reaction of uranium metal with water were identified by surveying the technical literature. The underlying chemistry and potential side reactions were explored by conducting 61 principal experiments. Several methods achieved significant hydrogen gas generation rate mitigation. Gas-generating side reactions from interactions of organics or sludge constituents with mitigating agents were observed. Further testing is recommended to develop deeper knowledge of the underlying chemistry and to advance the technology aturation level. Uranium metal reacts with water in K Basin sludge to form uranium hydride (UH3), uranium dioxide or uraninite (UO2), and diatomic hydrogen (H2). Mechanistic studies show that hydrogen radicals (H·) and UH3 serve as intermediates in the reaction of uranium metal with water to produce H2 and UO2. Because H2 is flammable, its release into the gas phase above K Basin sludge during sludge storage, processing, immobilization, shipment, and disposal is a concern to the safety of those operations. Findings from the technical literature and from experimental investigations with simple chemical systems (including uranium metal in water), in the presence of individual sludge simulant components, with complete sludge simulants, and with actual K Basin sludge are presented in this report. Based on the literature review and intermediate lab test results, sodium nitrate, sodium nitrite, Nochar Acid Bond N960, disodium hydrogen phosphate, and hexavalent uranium [U(VI)] were tested for their effects in decreasing the rate of hydrogen generation from the reaction of uranium metal with water. Nitrate and nitrite each were effective, decreasing hydrogen generation rates in actual sludge by factors of about 100 to 1000 when used at 0.5 molar (M) concentrations. Higher attenuation factors were achieved in tests with aqueous solutions alone. Nochar N960, a water sorbent, decreased hydrogen

  11. Exchange reaction between tritiated hydrogen and water vapor

    International Nuclear Information System (INIS)

    Yamada, Koichi; Takano, Kenichi; Watanabe, Tamaki.

    1979-01-01

    Exchange reaction of tritiated hydrogen to water vapor under the condition of tritium gas concentration between 1 μCi/l and 1 mCi/l was studied. Tritium gas with hydrogen gas of 5 Torr and water of 20 mg were enclosed in a Pyrex glass ampule with volume of about 100 ml. The mixed gas with water vapor was heated with electric furnace. The heating time was between 2 and 100 hr, and the temperature was 776, 725, 675, 621, and 570.5 0 K. After heating, tritiated water was trapped with liquid nitrogen, and counted with a liquid scintillation counter. The radioactive concentration of initial tritiated hydrogen was measured with a calibrated ionization chamber. The main results obtained are as follows; 1) the concentration of produced tritiated water is well proportioned to that of initial tritiated hydrogen, 2) the activation energy of exchange reaction from tritiated hydrogen to tritiated water is 26.2 kcal/mol and that of inverse reaction is 27.4 kcal/mol, 3) the reaction rate at room temperature which calculated with activation energy is 1.04 x 10 -13 day -1 , and then exchange reaction at room temperature is negligible. (author)

  12. Rapid Hydrogen Shift Reactions in Acyl Peroxy Radicals

    DEFF Research Database (Denmark)

    Knap, Hasse Christian; Jørgensen, Solvejg

    2017-01-01

    -shift with X = 6, 7, 8, or 9) in the hydroperoxy acyl peroxy radicals, this H-shift is a reversible reaction and it scrambles between two peroxides, hydroperoxy acyl peroxy and peroxy peroxoic acid radicals. The forward reaction rate constants of the 1,X-OOH H-shift reactions are estimated to be above 103 s–1...... with transition state theory corrected with Eckart quantum tunnelling correction. The ratio between the forward and reverse reaction rate constant of the 1,X-OOH H-shift reactions is around ∼105. Therefore, the equilibrium is pushed toward the production of peroxy peroxoic acid radicals. These very fast 1,X-OOH H......We have used quantum mechanical chemical calculations (CCSD(T)-F12a/cc-pVDZ-F12//M06-2X/aug-cc-pVTZ) to investigate the hydrogen shift (H-shift) reactions in acyl peroxy and hydroperoxy acyl peroxy radicals. We have focused on the H-shift reactions from a hydroperoxy group (OOH) (1,X-OOH H...

  13. Integrated Water Gas Shift Membrane Reactors Utilizing Novel, Non Precious Metal Mixed Matrix Membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ferraris, John P. [Univ. of Texas-Dallas, Richardson, TX (United States). Dept. of Chemistry

    2013-09-30

    Nanoparticles of zeolitic imidazolate frameworks and other related hybrid materials were prepared by modifying published synthesis procedures by introducing bases, changing stoichiometric ratios, or adjusting reaction conditions. These materials were stable at temperatures >300 °C and were compatible with the polymer matrices used to prepare mixed- matrix membranes (MMMs). MMMs tested at 300 °C exhibited a >30 fold increase in permeability, compared to those measured at 35 °C, while maintaining H2/CO2 selectivity. Measurements at high pressure (up to 30 atm) and high temperature (up to 300 °C) resulted in an increase in gas flux across the membrane with retention of selectivity. No variations in permeability were observed at high pressures at either 35 or 300 °C. CO2-induced plasticization was not observed for Matrimid®, VTEC, and PBI polymers or their MMMs at 30 atm and 300 °C. Membrane surface modification by cross-linking with ethanol diamine resulted in an increase in H2/CO2 selectivity at 35 °C. Spectrometric analysis showed that the cross-linking was effective to temperatures <150 °C. At higher temperatures, the cross-linked membranes exhibit a H2/CO2 selectivity similar to the uncross-linked polymer. Performance of the polybenzimidazole (PBI) hollow fibers prepared at Santa Fe Science and Technology (SFST, Inc.) showed increased flux and selectivity at 300 °C, which is comparable to a flat PBI membrane. A water-gas shift reactor has been built and currently being optimized for testing under DOE conditions.

  14. Investigation on the combined operation of water gas shift and preferential oxidation reactor system on the kW scale

    NARCIS (Netherlands)

    O'Connell, M.; Kolb, G.A.; Schelhaas, K.P.; Schuerer, J.; Tiemann, D.; Keller, S.; Reinhard, D.; Hessel, V.

    2010-01-01

    A 5 kWel water gas shift reactor was integrated with a 5 kWel preferential oxidation reactor for the purposes of reducing the carbon monoxide levels in a reformate exit stream to levels below 100 ppm. The integrated system worked best at partial load with CO concentrations being reduced to 40 ppm at

  15. Reaction path analysis of sodium-water reaction phenomena in support of chemical reaction model development

    International Nuclear Information System (INIS)

    Kikuchi, Shin; Ohshima, Hiroyuki; Hashimoto, Kenro

    2011-01-01

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule to the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. The results are used as the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by JAEA toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR). (author)

  16. Numerical thermal-hydraulics study on sodium-water reaction phenomena

    International Nuclear Information System (INIS)

    Takashi, Takata; Akira, Yamaguchi

    2003-01-01

    A new computational program SERAPHIM (Sodium-watEr Reaction Analysis: PHysics of Interdisciplinary Multi-phase flow) is developed to investigate the Sodium-Water Reaction (SWR) phenomena based on parallel computation technology. A compressible three-fluid (liquid water, liquid sodium and mixture gas) and one-pressure model is adopted for multi-phase calculation. The Highly Simplified Maker And Cell (HSMAC) method considering with compressibility is implemented as the numerical solution. The Message-Passing Interface (MPI) is used for the parallel computation. Two types of reactions are considered for the SWR modeling; one is a surface reaction and the other is a gas phase reaction. The surface reaction model assumes that liquid sodium reacts with water vapor on the surface of liquid sodium. An analogy of heat transfer and mass transfer is applied in this model. Reaction heating vaporizes liquid sodium resulting in the gas phase reaction. The ab initio molecular orbital method is applied to investigate the reaction mechanism and evaluate the reaction rate described by the Arrhenius law. A performance of parallel computation is tested on the cluster-PC (16 CPUs) system. The execution time becomes 17.1 times faster in case of 16 CPUs. It seems promising that the SERAPHIM code is practicable for large-scale analysis of the SWR phenomena. Three-dimensional SWR analyses are also carried out to investigate the characteristics of the thermal-hydraulics with the SWR and an influence of initial pressure (0.2 MPa and 0.6 MPa) on an early stage of the SWR phenomenon. As a result, distribution of a gas region, in which water vapor or product of the SWR such as hydrogen and sodium hydroxide exits, velocity and high temperature region differs by 0.2 MPa and 0.6 MPa conditions. However, the maximum gas temperature has an upper bounding and is almost constant both in the analyses. The reason of the upper bounding is attributed to the fact that a hydrogen gas covers up a liquid-gas

  17. Two-stage coal liquefaction without gas-phase hydrogen

    Science.gov (United States)

    Stephens, H.P.

    1986-06-05

    A process is provided for the production of a hydrogen-donor solvent useful in the liquefaction of coal, wherein the water-gas shift reaction is used to produce hydrogen while simultaneously hydrogenating a donor solvent. A process for the liquefaction of coal using said solvent is also provided. The process enables avoiding the use of a separate water-gas shift reactor as well as high pressure equipment for liquefaction. 3 tabs.

  18. Copper-chromium compounds formed in the preparation of a low-temperature water gas shift catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sharkina, V I; Salomatin, G I; Boevskaya, E A

    1978-12-01

    IR and X-ray phase analyses of commercial water gas shift catalyst samples prepared by mixing solid chromic anhydride, basic copper carbonate (malachite), aluminum hydroxide, and water at 70/sup 0/-100/sup 0/C and 0.35:1 to 1.2:1 ratio of water to solid components (R) showed the formation of a basic copper chromate (BCC) CuCrO/sub 4/-2CuO-2H/sub 2/O at 80/sup 0/C (any R) and at 100/sup 0/C and R Vertical Bar3: 1.2:1, but at 100/sup 0/C and lower R (especially at R 0.7:1), a different, unidentified phase was formed. The samples containing these two phases had different colors; the high-temperature, low-water phase showed lower thermal stability but higher catalytic activity than the BCC. The BCC catalyst samples contained less unreacted malachite and their IR spectra contained a 3100-3200/cm band characteristic of hydroxyls associated by hydrogen bonds, and more molecular water, suggesting the formation of a hydroxo-polymeric structured system.

  19. Optimisation of Shift Reactor Operating Conditions to Maximise Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, J. M.; Marano, M.; Ruiz, E.

    2011-07-28

    This report compiles the results of the work conducted by CIEMAT for Task 6.5 Shift reaction of the FLEXGAS project Near Zero Emission Advanced Fluidized Bed Gasification, which has been carried out with financial support from the Research Fund for Coal and Steel, RFCR-CT-2007-00005. The activity of an iron-chromium-based catalyst for the water gas shift reaction is studied. Results about WGS experiments conducted by CIEMAT on laboratory scale under different operating conditions are presented. The influence on the activity of the catalyst of main operating parameters- temperature, pressure, excess steam, and space velocity and gas composition - is evaluated and discussed. (Author) 19 refs.

  20. Ethanol synthesis and water gas shift over bifunctional sulfide catalysts. Final technical progress report, September 12, 1991--December 11, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Klier, K.; Herman, R.G.; Deemer, M.; Richards-Babb, M.; Carr, T.

    1995-07-01

    The objective of this research was to investigate sulfur-resistant catalysts for the conversion of synthesis gas having H{sub 2}/CO {le} 1 into C{sub 1}--C{sub 4} alcohols, especially ethanol, by a highly selective and efficient pathway, while also promoting the water gas shift reaction (WGSR). The catalysts chosen are bifunctional, base-hydrogenation, sulfur-tolerant transition metal sulfides with heavy alkali, e.g. Cs{sup +}, promoter dispersed on their surfaces. The modes of activation of H{sub 2} and CO on MoS{sub 2} and alkali-doped MoS{sub 2} were considered, and computational analyses of the thermodynamic stability of transition metal sulfides and of the electronic structure of these sulfide catalysts were carried out. In the preparation of the cesium-promoted MoS{sub 2} catalysts, a variety of preparation methods using CsOOCH were examined. In all cases, doping with CsOOCH led to a lost of surface area. The undoped molybdenum disulfide catalyst only produced hydrocarbons. Cs-doped MoS{sub 2} catalysts all produced linear alcohols, along with smaller amounts of hydrocarbons. With a 20 wt% CsOOCH/MoS{sub 2} catalyst, temperature, pressure, and flow rate dependences of the synthesis reactions were investigated in the presence and absence of H{sub 2}S in the H{sub 2}/CO = 1/1 synthesis gas during short term testing experiments. It was shown that with a carefully prepared 10 wt% CsOOCH/MoS{sub 2} catalyst, reproducible and high alcohol synthesis activity could be obtained. For example, at 295 C with H{sub 2}/CO = 1 synthesis gas at 8.3 MPa and with GHSV = 7,760 l/kg cat/hr, the total alcohol space time yield was ca 300 g/kg cat/hr (accompanied with a hydrocarbon space time yield of ca 60 g/kg cat/hr). Over a testing period of ca 130 hr, no net deactivation of the catalyst was observed. 90 refs., 82 figs., 14 tabs.

  1. Hydrogen-Etched TiO2−x as Efficient Support of Gold Catalysts for Water–Gas Shift Reaction

    Directory of Open Access Journals (Sweden)

    Li Song

    2018-01-01

    Full Text Available Hydrogen-etching technology was used to prepare TiO2−x nanoribbons with abundant stable surface oxygen vacancies. Compared with traditional Au-TiO2, gold supported on hydrogen-etched TiO2−x nanoribbons had been proven to be efficient and stable water–gas shift (WGS catalysts. The disorder layer and abundant stable surface oxygen vacancies of hydrogen-etched TiO2−x nanoribbons lead to higher microstrain and more metallic Au0 species, respectively, which all facilitate the improvement of WGS catalytic activities. Furthermore, we successfully correlated the WGS thermocatalytic activities with their optoelectronic properties, and then tried to understand WGS pathways from the view of electron flow process. Hereinto, the narrowed forbidden band gap leads to the decreased Ohmic barrier, which enhances the transmission efficiency of “hot-electron flow”. Meanwhile, the abundant surface oxygen vacancies are considered as electron traps, thus promoting the flow of “hot-electron” and reduction reaction of H2O. As a result, the WGS catalytic activity was enhanced. The concept involved hydrogen-etching technology leading to abundant surface oxygen vacancies can be attempted on other supported catalysts for WGS reaction or other thermocatalytic reactions.

  2. Tax shifting in long-term gas sales contracts

    International Nuclear Information System (INIS)

    Asche, Frank; Osmundsen, Petter; Tveteraas, Ragnar

    2002-01-01

    Producers or consumers faced with an increase in taxes are usually able to shift parts of it to other levels in the value chain. We examine who are actually bearing the burden of increased taxes on natural gas in the EU-area - consumers or exporters. Strategic trade policy and cross-border consumer tax shifting are of particular interest, as the EU-area increasingly is a net importer of gas. Traditional tax incidence theory presumes spot markets. Natural gas in the EU-area, however, is to a large extent regulated by incomplete long-term contracts. Still, spot market forces could be indicative for tax shifting, by determining the ex post bargaining power in contract renegotiations. By examining tax shifting in gas sales data we test whether this is the case. To investigate tax incidence, we estimate natural gas demand elasticities for the household sector in EU countries as well as a reduced form import equation. We test whether gas import prices, which are predominantly determined by long-term contracts, have been influenced by end-user tax shifts. (author)

  3. Prediction of biomass-generated syngas using extents of major reactions in a continuous stirred-tank reactor

    International Nuclear Information System (INIS)

    Sharma, Ashokkumar M.; Kumar, Ajay; Madihally, Sundararajan; Whiteley, James R.; Huhnke, Raymond L.

    2014-01-01

    Syngas, the main gasification product, is a well-known intermediate for making fuels, chemicals and power. The objective of this study was to develop and validate reaction kinetics-based gasification model using extents of major reactions in a CSTR (continuous stirred-tank reactor) to predict syngas composition and yield. The model was studied by varying biomass and air flowrates from 2.9 to 4.2 dry kg/h and 4.5–10 kg/h, respectively, with temperature from 801 to 907 °C. Results showed significant improvement in the predictions of syngas composition and yield, and gasification efficiency. The extents of gasification reactions indicated that at ERs (equivalence ratios) below 0.32, the water gas reaction contributed the most to the syngas CO and H 2 yields. The char oxidation reaction was also the dominating reaction contributing to CO yield at ERs below 0.40. At ERs above 0.29, the Boudouard and methane oxidation reactions were the most dominating reactions contributing to the CO yield while the water gas shift reaction contributed to the H 2 yield. The developed model corrected one of the key underlying assumptions that biomass decomposes into elemental forms (C, H, O, N and S), however, gasification temperature, carbon conversion efficiency and tar yield were assumed to be given. - Highlights: • Modeled gasification using extent of reaction in a continuous stirred-tank reactor. • Extents of major reactions during gasification were predicted. • Model greatly improved prediction of biomass-generated gas composition and yield. • Water gas, Boudouard and methane oxidation reactions contributed to CO production. • Water gas and water gas shift were the dominating reactions for H 2 production

  4. The Atmospheric Oxidation of Volatile Organic Compounds Through Hydrogen Shift Reactions

    DEFF Research Database (Denmark)

    Knap, Hasse Christian

    a radical is denoted as a H-shift reaction. Quantum chemical calculations were carried out to investigate the potential energy surface of the H-shift reactions and the subsequent decomposition pathways. The transition state theory including the Eckart quantum tunneling correction have been used to calculate...... the reaction rate constants of the H-shift reactions. The autoxidation of volatile organic compounds is an important oxidation mechanism that produces secondary organic aerosols (SOA) and recycles hydroxyl (OH) radicals. The autoxidation cycle produces a second generation peroxy radical (OOQOOH) through...... a series of H-shift reactions and O2 attachments. I have investigated the H-shift reactions in two OOQOOH radicals (hydroperoxy peroxy radicals and hydroperoxy acyl peroxy radicals). The H-shift reaction rate constants have been compared with the bimolecular reaction rate constants of the peroxy radicals...

  5. A combined experimental and computational study of water-gas shift reaction over rod-shaped Ce0.75 M0.25O2 (M=Ti, Zr, and Mn) supported Cu catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Zhibo; Peng, Fei; Chen, Biaohua; Mei, Donghai; Li, Jianwei

    2017-11-02

    Water-gas shift (WGS) reaction over a series of ceria-based mixed oxides supported Cu catalysts was investigated using a combined experimental and theoretical method. The mixed rod-shaped Ce0.75M0.25O2 (M = Ti4+, Zr4+, Mn4+) solid solutions, which majorly expose the (110) and (100) facets, are synthesized by hydrothermal method and used to prepare supported Cu catalysts. We found that the Cu/Ce0.75Ti0.25O2 (Cu-CT) exhibits the highest CO conversion in the temperature range of 150-250 °C among all supported Cu catalysts. This is mainly attributed to (i) good dispersion of Cu; (ii) largest amount of moderate copper oxide; and (iii) strongest Cu-support interaction of Cu-CT. And compared to other mixed metals, periodic density functional theory calculations performed, this work further suggest that the introduction of Ti into CeO2 not only promotes oxygen vacancy formation and CO adsorption, but also facilitates the carboxyl (COOH) formation at the interface of the Cu cluster and the support, which leads to the enhanced catalytic activity of the Cu-CT toward WGS reaction.

  6. CFD and FEM thermo-mechanical design of a recuperative-dissipative heat exchanger for a laboratory water gas shift reactor

    Energy Technology Data Exchange (ETDEWEB)

    Michele Vascellari; Stefano Sollai; Pier Francesco Orru; Giorgio Cau [University of Cagliari, Cagliari (Italy). Department of Mechanical Engineering

    2007-07-01

    A small scale test rig based on a two-stage reactor for testing water gas shift conversion processes has been set up at the Department of Mechanical Engineering at the University of Cagliari, chiefly for the purpose of supporting a pilot plant operation for high sulphur (Sulcis) coal gasification, gas cleaning and treatment, CO{sub 2} separation, hydrogen and electricity production. The laboratory test rig comprises two packed-bed reactors in series to be operated at different temperatures and has been designed for testing CO-shift conversion processes using a variety of catalysts for different syngas temperatures (up to 500{sup o}C) and compositions. One critical component of the system is a recuperative-dissipative heat exchanger placed between the two reactors. The heat exchanger, which preheats the syngas prior to entering the high temperature reactor and cools the shifted gas exiting there from, prior to its entering the low temperature reactor, is subjected to severe thermo-mechanical stress. Thus the design and analysis of this component, described herein, is a critical issue. A full 3D conjugate heat transfer CFD analysis of the tubular heat exchanger has been performed, considering different geometries. Based on the CFD results we were able to verify the preliminary design of the component, carried out using simple thermal correlations and to predict wall temperature distribution for the thermo-structural analysis. 10 refs., 10 figs., 2 tabs.

  7. Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Hrdlicka, J.; Feik, C.; Carpenter, D.; Pomeroy, M.

    2008-12-01

    With oak and pine feedstocks, the Gasification of Biomass to Hydrogen project maximizes hydrogen production using the Full Stream Reformer during water-gas shift fixed-bed reactor testing. Results indicate that higher steam-to-biomass ratio and higher thermal cracker temperature yield higher hydrogen concentration. NREL's techno-economic models and analyses indicate hydrogen production from biomass may be viable at an estimated cost of $1.77/kg (current) and $1.47/kg (advanced in 2015). To verify these estimates, NREL used the Thermochemical Process Development Unit (TCPDU), an integrated system of unit operations that investigates biomass thermochemical conversion to gaseous and liquid fuels and chemicals.

  8. Life-cycle comparison of greenhouse gas emissions and water consumption for coal and shale gas fired power generation in China

    International Nuclear Information System (INIS)

    Chang, Yuan; Huang, Runze; Ries, Robert J.; Masanet, Eric

    2015-01-01

    China has the world's largest shale gas reserves, which might enable it to pursue a new pathway for electricity generation. This study employed hybrid LCI (life cycle inventory) models to quantify the ETW (extraction-to-wire) GHG (greenhouse gas) emissions and water consumption per kWh of coal- and shale gas-fired electricity in China. Results suggest that a coal-to-shale gas shift and upgrading coal-fired power generation technologies could provide pathways to less GHG and water intensive power in China. Compared to different coal-fired generation technologies, the ETW GHG emissions intensity of gas-fired CC (combined cycle) technology is 530 g CO 2 e/kWh, which is 38–45% less than China's present coal-fired electricity. Gas-fired CT (combustion turbine) technology has the lowest ETW water consumption intensity at 960 g/kWh, which is 34–60% lower than China's present coal-fired electricity. The GHG-water tradeoff of the two gas-fired power generation technologies suggests that gas-fired power generation technologies should be selected based on regional-specific water resource availabilities and electricity demand fluctuations in China. However, the low price of coal-fired electricity, high cost of shale gas production, insufficient pipeline infrastructures, and multiple consumers of shale gas resources may serve as barriers to a coal-to-shale gas shift in China's power sector in the near term. - Highlights: • The GHG and water footprints of coal- and shale gas-fired electricity are estimated. • A coal-to-shale gas shift can enable less GHG and water intensive power in China. • The GHG emissions of shale gas-fired combined cycle technology is 530 g CO 2 e/kWh. • The water consumption of shale gas-fired combustion turbine technology is 960 g/kWh. • Shale gas-fired power generation technologies selection should be regional-specific

  9. Impact of Contaminants Present in Coal-Biomass Derived Synthesis Gas on Water-gas Shift and Fischer-Tropsch Synthesis Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Alptekin, Gokhan [TDA Research, Inc., Wheat Ridge, CO (United States)

    2013-02-15

    Co-gasification of biomass and coal in large-scale, Integrated Gasification Combined Cycle (IGCC) plants increases the efficiency and reduces the environmental impact of making synthesis gas ("syngas") that can be used in Coal-Biomass-to-Liquids (CBTL) processes for producing transportation fuels. However, the water-gas shift (WGS) and Fischer-Tropsch synthesis (FTS) catalysts used in these processes may be poisoned by multiple contaminants found in coal-biomass derived syngas; sulfur species, trace toxic metals, halides, nitrogen species, the vapors of alkali metals and their salts (e.g., KCl and NaCl), ammonia, and phosphorous. Thus, it is essential to develop a fundamental understanding of poisoning/inhibition mechanisms before investing in the development of any costly mitigation technologies. We therefore investigated the impact of potential contaminants (H2S, NH3, HCN, AsH3, PH3, HCl, NaCl, KCl, AS3, NH4NO3, NH4OH, KNO3, HBr, HF, and HNO3) on the performance and lifetime of commercially available and generic (prepared in-house) WGS and FT catalysts.

  10. Theoretical analysis of a biogas-fed PEMFC system with different hydrogen purifications: Conventional and membrane-based water gas shift processes

    International Nuclear Information System (INIS)

    Authayanun, Suthida; Aunsup, Pounyaporn; Patcharavorachot, Yaneeporn; Arpornwichanop, Amornchai

    2014-01-01

    Highlights: • Thermodynamic analysis of the biogas-fed PEMFC system is performed. • Conventional and membrane-based WGS processes for H 2 purification are studied. • A flowsheet model of the PEMFC system is developed. • Effect of key parameters on yields of H 2 and carbon in the biogas reformer is shown. • Performance of PEMFC systems with different H 2 purification processes is analyzed. - Abstract: This study presents a thermodynamic analysis of biogas reforming and proton electrolyte membrane fuel cell (PEMFC) integrated process with different hydrogen purifications: conventional and membrane-based water gas shift processes. The aim is to determine the optimal reforming process for hydrogen production from biogas in the PEMFC system. The formation of carbon is concerned in the hydrogen production. The simulation results show that increases in the steam-to-methane ratio and reformer temperature can improve the hydrogen yield and reduce the carbon formation. From the performance analysis, it is found that when the PEMFC is operated at high temperature and fuel utilization, the overall system efficiency enhances. The performance of the PEMFC system with the installation of a water gas shift membrane unit in the hydrogen purification step is slightly increased, compared with a conventional process

  11. Theoretical Study of Sodium-Water Surface Reaction Mechanism

    Science.gov (United States)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR).

  12. Theoretical study of sodium-water surface reaction mechanism

    International Nuclear Information System (INIS)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    2012-01-01

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR). (author)

  13. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  14. Raney copper catalysts for the water-gas shift reaction - II. Initial catalyst optimisation

    CSIR Research Space (South Africa)

    Mellor, JR

    1997-12-23

    Full Text Available The initial Raney copper WGS activity based on catalyst volume has been shown to be comparable to industrial and co-precipitated alternatives under varying reaction conditions. The presence of zinc oxide in the Raney copper structure was shown...

  15. Water-gas shift. An examination of Pt promoted MgO and tetragonal and monoclinic ZrO2 by in situ drifts

    International Nuclear Information System (INIS)

    Chenu, Emilie; Jacobs, Gary; Crawford, Adam C.; Keogh, Robert A.; Patterson, Patricia M.; Sparks, Dennis E.; Davis, Burtron H.

    2005-01-01

    In situ DRIFTS measurements on unpromoted and Pt promoted MgO and ZrO 2 (both tetragonal and monoclinic) indicate that at high H 2 O/CO ratios, where the reaction rate has been reported to be zero order in H 2 O and first order in CO, the mechanism involved in the catalysis of water-gas shift is likely a surface formate mechanism, in agreement with Shido and Iwasawa. Pt was found to catalyze the removal of surface carbonates and to facilitate the generation of active OH groups relative to the unpromoted catalyst. Comparison with Pt/ceria revealed that the OH groups involved in the catalysis of magnesia and zirconia may be those of the bridging variety which occur at defect sites. That is, water dissociated over vacancies to produce bridging OH groups, as observed by infrared spectroscopy. The existence of such an adsorbed species is implied in the zero reaction order for water, where kinetics suggests that the surface should be saturated by an adsorbed water species. The lower extent of vacancy formation for magnesia and zirconia-based materials in comparison with ceria could explain a lower surface population of active bridging OH groups. CO was used as a probe molecule of the reduced centers, as it reacts with bridging OH groups to generate surface formates, a proposed WGS intermediate, and the decomposition of which is proposed to be the rate-limiting step. The trends in formate intensity by CO adsorption and CO conversion in WGS catalytic testing both followed the order: Pt/ceria>Pt/m-zirconia>Pt/t-zirconia>Pt/magnesia. In all cases, a normal kinetic isotope effect was observed in switching from H 2 O to D 2 O, consistent with a link between the rate-limiting step and the decomposition of surface formates, as noted previously by Shido and Iwasawa for Rh/ceria, MgO, and ZnO

  16. Shifts in microbial community structure and function in surface waters impacted by unconventional oil and gas wastewater revealed by metagenomics

    Science.gov (United States)

    Fahrenfeld, N.L.; Reyes, Hannah Delos; Eramo, Alessia; Akob, Denise M.; Mumford, Adam; Cozzarelli, Isabelle M.

    2017-01-01

    Unconventional oil and gas (UOG) production produces large quantities of wastewater with complex geochemistry and largely uncharacterized impacts on surface waters. In this study, we assessed shifts in microbial community structure and function in sediments and waters upstream and downstream from a UOG wastewater disposal facility. To do this, quantitative PCR for 16S rRNA and antibiotic resistance genes along with metagenomic sequencing were performed. Elevated conductivity and markers of UOG wastewater characterized sites sampled downstream from the disposal facility compared to background sites. Shifts in overall high level functions and microbial community structure were observed between background sites and downstream sediments. Increases in Deltaproteobacteria and Methanomicrobia and decreases in Thaumarchaeota were observed at downstream sites. Genes related to dormancy and sporulation and methanogenic respiration were 18–86 times higher at downstream, impacted sites. The potential for these sediments to serve as reservoirs of antimicrobial resistance was investigated given frequent reports of the use of biocides to control the growth of nuisance bacteria in UOG operations. A shift in resistance profiles downstream of the UOG facility was observed including increases in acrB and mexB genes encoding for multidrug efflux pumps, but not overall abundance of resistance genes. The observed shifts in microbial community structure and potential function indicate changes in respiration, nutrient cycling, and markers of stress in a stream impacted by UOG waste disposal operations.

  17. Magnetic susceptibility as a direct measure of oxidation state in LiFePO4 batteries and cyclic water gas shift reactors.

    Science.gov (United States)

    Kadyk, Thomas; Eikerling, Michael

    2015-08-14

    The possibility of correlating the magnetic susceptibility to the oxidation state of the porous active mass in a chemical or electrochemical reactor was analyzed. The magnetic permeability was calculated using a hierarchical model of the reactor. This model was applied to two practical examples: LiFePO4 batteries, in which the oxidation state corresponds with the state-of-charge, and cyclic water gas shift reactors, in which the oxidation state corresponds to the depletion of the catalyst. In LiFePO4 batteries phase separation of the lithiated and delithiated phases in the LiFePO4 particles in the positive electrode gives rise to a hysteresis effect, i.e. the magnetic permeability depends on the history of the electrode. During fast charge or discharge, non-uniform lithium distributionin the electrode decreases the hysteresis effect. However, the overall sensitivity of the magnetic response to the state-of-charge lies in the range of 0.03%, which makes practical measurement challenging. In cyclic water gas shift reactors, the sensitivity is 4 orders of magnitude higher and without phase separation, no hysteresis occurs. This shows that the method is suitable for such reactors, in which large changes of the magnetic permeability of the active material occurs.

  18. Support effects and catalytic trends for water gas shift activity of transition metals

    DEFF Research Database (Denmark)

    Boisen, Astrid; Janssens, T.V.W.; Schumacher, Nana Maria Pii

    2010-01-01

    Water gas shift activity measurements for 12 transition metals (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Re, Ir, Pt, Au) supported on inert MgAl2O4 and Ce0.75Zr0.25O2 are presented, to elucidate the influence of the active metal and the support. The activity is related to the adsorption energy of molecular...... activity on the MgAl2O4 support and are both characterized by weak CO adsorption. For the MgAl2O4-supported catalysts a volcano-type relation between the activity and the adsorption energy of atomic oxygen on the metal is obtained. The maximum activity is found for metals with a binding energy of oxygen...... around −2.5 eV. No clear correlation exists with the adsorption energy of CO. In contrast, the activity for the Ce0.75Zr0.25O2 support increases with increasing adsorption strength for CO, and based on a relatively low activity of Cu the activity does not seem to depend on the adsorption energy of oxygen...

  19. Application of Enzyme Coupling Reactions to Shift Thermodynamically Limited Biocatalytic Reactions

    DEFF Research Database (Denmark)

    Abu, Rohana; Woodley, John M.

    2015-01-01

    , it can be challenging to combine several engineered enzymes in vitro for the conversion of non-natural substrates. In this mini-review we focus on enzyme coupling reactions as a tool to alleviate thermodynamic constraints in synthetically useful biocatalytic reactions. The implications of thermodynamic...... shift the equilibrium of otherwise thermodynamically unfavourable reactions to give a higher conversion of the target product. By coupling an energetically unfavourable reaction with a more favourable one, the multi-enzyme cascade mimics the approach taken in nature in metabolic pathways. Nevertheless...

  20. Studies in the reaction dynamics of beam-gas chemiluminescent reactions

    International Nuclear Information System (INIS)

    Prisant, M.G.

    1984-01-01

    This thesis develops techniques for the analysis and interpretation of data obtained from beam-gas chemiluminescence experiments. These techniques are applied to experimental studies of atom transfer reactions of the type A + BC → AB + C. A procedure is developed for determining the product rotational alignment in the center-of-mass frame from polarization measurements of chemiluminescent atom-diatom exchange reactions under beam-gas conditions. Knowledge of a vector property of a reaction, such as product alignment, provides information on the disposition of angular momentum by a chemical reaction. Fluorescence polarization and hence product alignment are measured for two prototype reactions. The reaction of metastable calcium atoms with hydrogen-chloride gas yields highly aligned calcium-chloride product which exhibits little variation of alignment with vibrational state. The reaction of ground-state calcium with fluorine gas yields moderately aligned product which shows strong variation of alignment with vibration. A multi-surface direct-interaction model is developed to interpret product alignment and population data. The predictions of this model for the reaction of calcium with fluorine show reasonable agreement with experiment

  1. The production of hydrogen through the use of a 77 wt% Pd 23 wt% Ag membrane water gas shift reactor

    Directory of Open Access Journals (Sweden)

    Liberty N. Baloyi

    2016-12-01

    Full Text Available Hydrogen as an energy carrier has the potential to decarbonize the energy sector. This work presents the application of a palladium-silver (Pd–Ag membrane-based reactor. The membrane reactor which is made from Pd–Ag film supported by porous stainless steel (PSS is evaluated for the production of hydrogen and the potential replacement of the current two-stage Water-Gas Shift (WGS reaction by a single stage reaction. The permeability of a 20 μm Pd–Ag membrane reactor was examined at 320 °C, 380 °C and 430 °C. The effect of continuous hydrogen exposure on the Pd–Ag membrane at high temperature and low temperature was examined to investigate the thermal stability and durability of the membrane. During continuous operation to determine thermal stability, the membrane reactor exhibited stable hydrogen permeation at 320 °C for 120 h and unstable hydrogen permeation at 430 °C was observed. For the WGS reaction, the reactor was loaded with Ferrochrome catalyst. The membrane showed the ability to produce high purity hydrogen, with a CO conversion and an H2 recovery of 84% and 88%, respectively. The membrane suffered from hydrogen embrittlement due to desorption and adsorption of hydrogen on the membrane surface. SEM analysis revealed cracks that occurred on the surface of the membrane after hydrogen exposure. XRD analysis revealed lattice expansion after hydrogen loading which suggests the occurrence of phase change from α-phase to the more brittle β-phase.

  2. Hydrogen production by absorption enhanced water gas shift (AEWGS)

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo Bretado, Miguel A. [Facultad de Ciencias Quimicas, Universidad Juarez del Estado de Durango, Ave. Veterinaria s/n, Circuito Universitario, Durango 34120 (Mexico); Departamento de Quimica de Materiales, Centro de Investigacion en Materiales Avanzados, S.C. Miguel de Cervantes 120, Chihuahua, Chih. 31109 (Mexico); Delgado Vigil, Manuel D.; Gutierrez, Jesus Salinas; Lopez Ortiz, Alejandro; Collins-Martinez, Virginia [Departamento de Quimica de Materiales, Centro de Investigacion en Materiales Avanzados, S.C. Miguel de Cervantes 120, Chihuahua, Chih. 31109 (Mexico)

    2010-11-15

    AEWGS is a reaction that combines the WGS reaction and CO{sub 2} capture by a solid absorbent to produce high purity H{sub 2} from synthesis gas in one single step at 600-800 C. This reactor system, if homogeneous, would not require a catalyst. However, previous research on this concept was not conclusive, since a steel reactor was used and reactor walls were suspected to act as catalyst. Therefore, there is a need to address this issue and to select and evaluate suitable CO{sub 2} absorbents for this concept. AEWGS was studied using a quartz-made fixed-bed reactor at; SV = 3000 h{sup -1}, feed; 5% CO, 15% H{sub 2}O, balance He-N{sub 2} at 600 C, 1 atm. CO{sub 2} absorbents tested were CaO*MgO, and Na{sub 2}ZrO{sub 3}. Empty quartz-reactor tests leaded to conclude that a catalyst is needed for the WGS at temperatures of interest. A 97% H{sub 2} product was obtained with calcined dolomite suggesting this last to act as a WGS catalyst. (author)

  3. Shale gas vs. coal: Policy implications from environmental impact comparisons of shale gas, conventional gas, and coal on air, water, and land in the United States

    International Nuclear Information System (INIS)

    Jenner, Steffen; Lamadrid, Alberto J.

    2013-01-01

    The aim of this paper is to examine the major environmental impacts of shale gas, conventional gas and coal on air, water, and land in the United States. These factors decisively affect the quality of life (public health and safety) as well as local and global environmental protection. Comparing various lifecycle assessments, this paper will suggest that a shift from coal to shale gas would benefit public health, the safety of workers, local environmental protection, water consumption, and the land surface. Most likely, shale gas also comes with a smaller GHG footprint than coal. However, shale gas extraction can affect water safety. This paper also discusses related aspects that exemplify how shale gas can be more beneficial in the short and long term. First, there are technical solutions readily available to fix the most crucial problems of shale gas extraction, such as methane leakages and other geo-hazards. Second, shale gas is best equipped to smoothen the transition to an age of renewable energy. Finally, this paper will recommend hybrid policy regulations. - Highlights: ► We examine the impacts of (un)conventional gas and coal on air, water, and land. ► A shift from coal to shale gas would benefit public health. ► Shale gas extraction can affect water safety. ► We discuss technical solutions to fix the most crucial problems of shale gas extraction. ► We recommend hybrid regulations.

  4. Non-equilibrium thermodynamics of highly rarefied neutron gas under creative and destructive reactions

    International Nuclear Information System (INIS)

    Hayasaka, Hideo

    1978-01-01

    The thermodynamic structures of non-equilibrium steady states of a highly rarefied neutron gas in various media are considered in terms of the irreversible processes due to creative and destructive reactions of neutrons with nuclei of these media and to neutrons supplied from external sources. The respective subsystems of the stationary neutron gas are regarded as imperfect equilibrium systems in the presence of the medium and the external neutron sources, and are treated like different species in a mixture. The entropy production due to neutron-nuclear reactions has a minimum value at the steady state. The distribution function of such a neutron gas is determined from the extremum condition in which entropy does not change, and is expressed as a shifted Boltzmann distribution specified by the respective values of the generalized chemical potential for each energy level. (author)

  5. Graphite-moderated and heavy water-moderated spectral shift controlled reactors

    International Nuclear Information System (INIS)

    Alcala Ruiz, F.

    1984-01-01

    It has been studied the physical mechanisms related with the spectral shift control method and their general positive effects on economical and non-proliferant aspects (extension of the fuel cycle length and low proliferation index). This methods has been extended to non-hydrogenous fuel cells of high moderator/fuel ratio: heavy water cells have been con- trolled by graphite rods graphite-moderated and gas-cooled cells have been controlled by berylium rods and graphite-moderated and water-cooled cells have been controlled by a changing mixture of heavy and light water. It has been carried out neutron and thermal analysis on a pre design of these types of fuel cells. We have studied its neutron optimization and their fuel cycles, temperature coefficients and proliferation indices. Finally, we have carried out a comparative analysis of the fuel cycles of conventionally controlled PWRs and graphite-moderated, water-cooled and spectral shift controlled reactors. (Author) 71 refs

  6. Gaseous exchange reaction of deuterium between hydrogen and water on hydrophobic catalyst supporting platinum

    International Nuclear Information System (INIS)

    Izawa, Hirozumi; Isomura, Shohei; Nakane, Ryohei.

    1979-01-01

    The deuterium exchange reaction between hydrogen and water in the gas phase where the fed hydrogen gas is saturated with water vapor is studied experimentally by use of the proper hydrophobic catalysts supporting platinum. It is found that the activities of those catalysts for this reaction system are very high compared with the other known ones for the systems in which gas and liquid should coexist on catalyst surfaces, and that the apparent catalytic activity becomes larger as the amount of platinum supported on a catalyst particle increases. By analyses of the data the following informations are obtained. The exchange reaction can be expressed by a first order reversible reaction kinetics. The pore diffusion in the catalyst particles has significant effect on the overall reaction mechanisms. (author)

  7. LYAPUNOV-Based Sensor Failure Detection and Recovery for the Reverse Water Gas Shift Process

    Science.gov (United States)

    Haralambous, Michael G.

    2002-01-01

    Livingstone, a model-based AI software system, is planned for use in the autonomous fault diagnosis, reconfiguration, and control of the oxygen-producing reverse water gas shift (RWGS) process test-bed located in the Applied Chemistry Laboratory at KSC. In this report the RWGS process is first briefly described and an overview of Livingstone is given. Next, a Lyapunov-based approach for detecting and recovering from sensor failures, differing significantly from that used by Livingstone, is presented. In this new method, models used are in t e m of the defining differential equations of system components, thus differing from the qualitative, static models used by Livingstone. An easily computed scalar inequality constraint, expressed in terms of sensed system variables, is used to determine the existence of sensor failures. In the event of sensor failure, an observer/estimator is used for determining which sensors have failed. The theory underlying the new approach is developed. Finally, a recommendation is made to use the Lyapunov-based approach to complement the capability of Livingstone and to use this combination in the RWGS process.

  8. Acoustic detection for small-leak sodium-water reaction

    International Nuclear Information System (INIS)

    Nei, Hiromichi; Ohshima, Iwao; Ujihara, Kozaburo; Hori, Masao

    1977-01-01

    Characteristics of acoustic signal produced by sodium-water reaction due to steam injection and by Ar gas injection into sodium were experimentally investigated. Acoustic signal was measured by using Kistler 808A and 815A5 accelerometers. Root mean square (RMS) measurements and frequency analysis of the signal were conducted. The RMS measurements could detect a small water leakage into sodium, as small as 0.07g/sec, in the present loop. The peaks in a frequency spectrum were caused by the natural vibration of a rod on which the acoustic transducer was mounted. The RMS was approximately proportional to the one-third power of the steam leak rate and increased to some extent with the ambient sodium temperature. RMS values, both for sodium-water reaction and Ar gas injection, were about the same order of magnitude, when the data were plotted against the volumetric flow rates of steam and Argas. (auth.)

  9. Hot and Dry Cleaning of Biomass-Gasified Gas Using Activated Carbons with Simultaneous Removal of Tar, Particles, and Sulfur Compounds

    Directory of Open Access Journals (Sweden)

    Kinya Sakanishi

    2012-05-01

    Full Text Available This study proposes a gas-cleaning process for the simultaneous removal of sulfur compounds, tar, and particles from biomass-gasified gas using Fe-supported activated carbon and a water-gas shift reaction. On a laboratory scale, the simultaneous removal of H2S and COS was performed under a mixture of gases (H2/CO/CO2/CH4/C2H4/N2/H2S/COS/steam. The reactions such as COS + H2 → H2S + CO and COS + H2O → H2S + CO2 and the water-gas shift reaction were promoted on the Fe-supported activated carbon. The adsorption capacity with steam was higher than that without steam. On a bench scale, the removal of impurities from a gas derived from biomass gasification was investigated using two activated filters packed with Fe-supported activated carbon. H2S and COS, three- and four-ring polycyclic aromatic hydrocarbons (PAHs, and particles were removed and a water-gas shift reaction was promoted through the first filter at 320–350 °C. The concentrations of H2S and COS decreased to less than 0.1 ppmv. Particles and the one- and two-ring PAHs, except for benzene, were then removed through the second filter at 60–170 °C. The concentration of tar and particles decreased from 2428 to 102 mg Nm−3 and from 2244 to 181 mg Nm−3, respectively.

  10. Ammonia gas transport and reactions in unsaturated sediments: Implications for use as an amendment to immobilize inorganic contaminants

    International Nuclear Information System (INIS)

    Zhong, L.; Szecsody, J.E.; Truex, M.J.; Williams, M.D.; Liu, Y.

    2015-01-01

    Highlights: • Ammonia transport can be predicted from gas movement and equilibrium partitioning. • Ammonia diffusion rate in unsaturated sediment is a function of water contents. • High pH induced by ammonia causes mineral dissolution and sequential precipitation. • Ammonia treatment effectively immobilized uranium from contaminated sediments. - Abstract: Use of gas-phase amendments for in situ remediation of inorganic contaminants in unsaturated sediments of the vadose zone may be advantageous, but there has been limited development and testing of gas remediation technologies. Treatment with ammonia gas has a potential for use in treating inorganic contaminants (such as uranium) because it induces a high pore-water pH, causing mineral dissolution and subsequent formation of stable precipitates that decrease the mobility of some contaminants. For field application of this treatment, further knowledge of ammonia transport in porous media and the geochemical reactions induced by ammonia treatment is needed. Laboratory studies were conducted to support calculations needed for field treatment design, to quantify advective and diffusive ammonia transport in unsaturated sediments, to evaluate inter-phase (gas/sediment/pore water) reactions, and to study reaction-induced pore-water chemistry changes as a function of ammonia delivery conditions, such as flow rate, gas concentration, and water content. Uranium-contaminated sediment was treated with ammonia gas to demonstrate U immobilization. Ammonia gas quickly partitions into sediment pore water and increases the pH up to 13.2. Injected ammonia gas advection front movement can be reasonably predicted by gas flow rate and equilibrium partitioning. The ammonia gas diffusion rate is a function of the water content in the sediment. Sodium, aluminum, and silica pore-water concentrations increase upon exposure to ammonia and then decline as aluminosilicates precipitate when the pH declines due to buffering. Up to 85% of

  11. Water-Gas-Shift Membrane Reactor for High-Pressure Hydrogen Production. A comprehensive project report (FY2010 - FY2012)

    Energy Technology Data Exchange (ETDEWEB)

    Klaehn, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); Peterson, Eric [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bhandari, Dhaval [General Electric Global Research, Niskayuna, New York (United States); Miller, Scott [General Electric Global Research, Niskayuna, New York (United States); Ku, Anthony [General Electric Global Research, Niskayuna, New York (United States); Polishchuk, Kimberly [General Electric Global Research, Niskayuna, New York (United States); Narang, Kristi [General Electric Global Research, Niskayuna, New York (United States); Singh, Surinder [General Electric Global Research, Niskayuna, New York (United States); Wei, Wei [General Electric Global Research, Niskayuna, New York (United States); Shisler, Roger [General Electric Global Research, Niskayuna, New York (United States); Wickersham, Paul [General Electric Global Research, Niskayuna, New York (United States); McEvoy, Kevin [General Electric Global Research, Niskayuna, New York (United States); Alberts, William [General Electric Global Research, Niskayuna, New York (United States); Howson, Paul [General Electric Global Research, Niskayuna, New York (United States); Barton, Thomas [Western Research inst., Laramie, WY (United States); Sethi, Vijay [Western Research inst., Laramie, WY (United States)

    2013-01-01

    Idaho National Laboratory (INL), GE Global Research (GEGR), and Western Research Institute (WRI) have successfully produced hydrogen-selective membranes for water-gas-shift (WGS) modules that enable high-pressure hydrogen product streams. Several high performance (HP) polymer membranes were investigated for their gas separation performance under simulated (mixed gas) and actual syngas conditions. To enable optimal module performance, membranes with high hydrogen (H2) selectivity, permeance, and stability under WGS conditions are required. The team determined that the VTEC PI 80-051 and VTEC PI 1388 (polyimide from Richard Blaine International, Inc.) are prime candidates for the H2 gas separations at operating temperatures (~200°C). VTEC PI 80-051 was thoroughly analyzed for its H2 separations under syngas processing conditions using more-complex membrane configurations, such as tube modules and hollow fibers. These membrane formats have demonstrated that the selected VTEC membrane is capable of providing highly selective H2/CO2 separation (α = 7-9) and H2/CO separation (α = 40-80) in humidified syngas streams. In addition, the VTEC polymer membranes are resilient within the syngas environment (WRI coal gasification) at 200°C for over 1000 hours. The information within this report conveys current developments of VTEC PI 80-051 as an effective H2 gas separations membrane for high-temperature syngas streams.

  12. Quantum mechanical/molecular mechanical modeling finds Diels-Alder reactions are accelerated less on the surface of water than in water.

    Science.gov (United States)

    Thomas, Laura L; Tirado-Rives, Julian; Jorgensen, William L

    2010-03-10

    Quantum and molecular mechanics calculations for the Diels-Alder reactions of cyclopentadiene with 1,4-naphthoquinone, methyl vinyl ketone, and acrylonitrile have been carried out at the vacuum-water interface and in the gas phase. In conjunction with previous studies of these cycloadditions in dilute solution, a more complete picture of aqueous environmental effects emerges with implications for the origin of observed rate accelerations using heterogeneous aqueous suspensions, "on water" conditions. The pure TIP4P water slab maintains the bulk density and hydrogen-bonding properties in central water layers. The bulk region merges to vacuum over a ca. 5 A band with progressive diminution of the density and hydrogen bonding. The relative free energies of activation and transition structures for the reactions at the interface are found to be intermediate between those calculated in the gas phase and in bulk water; i.e., for the reaction with 1,4-naphthoquinone, the DeltaDeltaG(++) values relative to the gas phase are -3.6 and -7.3 kcal/mol at the interface and in bulk water, respectively. Thus, the results do not support the notion that a water surface is more effective than bulk water for catalysis of such pericyclic reactions. The trend is in qualitative agreement with expectations based on density considerations and estimates of experimental rate constants for the gas phase, a heterogeneous aqueous suspension, and a dilute aqueous solution for the reaction of cyclopentadiene with methyl vinyl ketone. Computed energy pair distributions reveal a uniform loss of 0.5-1.0 hydrogen bond for the reactants and transition states in progressing from bulk water to the vacuum-water interface. Orientational effects are apparent at the surface; e.g., the carbonyl group in the methyl vinyl ketone transition structure is preferentially oriented into the surface. Also, the transition structure for the 1,4-naphthoquinone case is buried more in the surface, and the free energy of

  13. Conversion of tritium gas to tritiated water in the environment

    International Nuclear Information System (INIS)

    Noguchi, Hiroshi; Kato, Shohei

    1985-01-01

    The literature on conversion of tritium gas to tritiated water in various environments is reviewed. The conversion mechanisms and the conversion rates are as follows. 1. In the oxidation with oxygen and the isotopic exchange with water, tritium β-rays and metal catalyst are effective. The oxidation rate is ∼ 0.02 %/day at initial tritium concentration ≤ 10 -2 Ci/l and ∼ 2 %/day at 1 Ci/l. In the presence of oxygen and water, it is not clear whether the exchange reaction occurs or not because of the small amount of data. 2. For biological conversion, soil microorganisms contribute significantly. The conversion rate is greater than 10 %/hr. The tritium gas deposition velocity, which includes the uptake rate of tritium gas by soil and the conversion rate, ranges from 0.0025 to 0.11 cm/sec and is influenced by temperature and moisture of the soil. 3. Tritium gas is converted to the tritiated water through the reaction with hydroxyl radical produced by sunlight in the atmosphere. (author)

  14. Bimolecular reactions of carbenes: Proton transfer mechanism

    Science.gov (United States)

    Abu-Saleh, Abd Al-Aziz A.; Almatarneh, Mansour H.; Poirier, Raymond A.

    2018-04-01

    Here we report the bimolecular reaction of trifluoromethylhydroxycarbene conformers and the water-mediated mechanism of the 1,2-proton shift for the unimolecular trans-conformer by using quantum chemical calculations. The CCSD(T)/cc-pVTZ//MP2/cc-pVDZ potential-energy profile of the bimolecular reaction of cis- and trans-trifluoromethylhydroxycarbene, shows the lowest gas-phase barrier height of 13 kJ mol-1 compared to the recently reported value of 128 kJ mol-1 for the unimolecular reaction. We expect bimolecular reactions of carbene's stereoisomers will open a valuable field for new and useful synthetic strategies.

  15. Research on Liquid Management Technology in Water Tank and Reactor for Propulsion System with Hydrogen Production System Utilizing Aluminum and Water Reaction

    Science.gov (United States)

    Imai, Ryoji; Imamura, Takuya; Sugioka, Masatoshi; Higashino, Kazuyuki

    2017-12-01

    High pressure hydrogen produced by aluminum and water reaction is considered to be applied to space propulsion system. Water tank and hydrogen production reactor in this propulsion system require gas and liquid separation function under microgravity condition. We consider to install vane type liquid acquisition device (LAD) utilizing surface tension in the water tank, and install gas-liquid separation mechanism by centrifugal force which swirling flow creates in the hydrogen reactor. In water tank, hydrophilic coating was covered on both tank wall and vane surface to improve wettability. Function of LAD in water tank and gas-liquid separation in reaction vessel were evaluated by short duration microgravity experiments using drop tower facility. In the water tank, it was confirmed that liquid was driven and acquired on the outlet due to capillary force created by vanes. In addition of this, it was found that gas-liquid separation worked well by swirling flow in hydrogen production reactor. However, collection of hydrogen gas bubble was sometimes suppressed by aluminum alloy particles, which is open problem to be solved.

  16. TRIMOLECULAR REACTIONS OF URANIUM HEXAFLUORIDE WITH WATER

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, M.; Becnel, J.; Garrison, S.

    2010-02-25

    The hydrolysis reaction of uranium hexafluoride (UF{sub 6}) is a key step in the synthesis of uranium dioxide (UO{sub 2}) powder for nuclear fuels. Mechanisms for the hydrolysis reactions are studied here with density functional theory and the Stuttgart small-core scalar relativistic pseudopotential and associated basis set for uranium. The reaction of a single UF{sub 6} molecule with a water molecule in the gas phase has been previously predicted to proceed over a relatively sizeable barrier of 78.2 kJ {center_dot} mol{sup -1}, indicating this reaction is only feasible at elevated temperatures. Given the observed formation of a second morphology for the UO{sub 2} product coupled with the observations of rapid, spontaneous hydrolysis at ambient conditions, an alternate reaction pathway must exist. In the present work, two trimolecular hydrolysis mechanisms are studied with density functional theory: (1) the reaction between two UF{sub 6} molecules and one water molecule, and (2) the reaction of two water molecules with a single UF{sub 6} molecule. The predicted reaction of two UF{sub 6} molecules with one water molecule displays an interesting 'fluorine-shuttle' mechanism, a significant energy barrier of 69.0 kJ {center_dot} mol{sup -1} to the formation of UF{sub 5}OH, and an enthalpy of reaction ({Delta}H{sub 298}) of +17.9 kJ {center_dot} mol{sup -1}. The reaction of a single UF{sub 6} molecule with two water molecules displays a 'proton-shuttle' mechanism, and is more favorable, having a slightly lower computed energy barrier of 58.9 kJ {center_dot} mol{sup -1} and an exothermic enthalpy of reaction ({Delta}H{sub 298}) of -13.9 kJ {center_dot} mol{sup -1}. The exothermic nature of the overall UF{sub 6} + 2 {center_dot} H{sub 2}O trimolecular reaction and the lowering of the barrier height with respect to the bimolecular reaction are encouraging; however, the sizable energy barrier indicates further study of the UF{sub 6} hydrolysis reaction

  17. Advanced gasifier and water gas shift technologies for low cost coal conversion to high hydrogen syngas

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, Andrew Kramer [Gas Technology Inst., Des Plaines, IL (United States)

    2016-09-30

    The Gas Technology Institute (GTI) and team members RTI International (RTI), Coanda Research and Development, and Nexant, are developing and maturing a portfolio of technologies to meet the United States Department of Energy (DOE) goals for lowering the cost of producing high hydrogen syngas from coal for use in carbon capture power and coal-to-liquids/chemicals. This project matured an advanced pilot-scale gasifier, with scalable and commercially traceable components, to readiness for use in a first-of-a-kind commercially-relevant demonstration plant on the scale of 500-1,000 tons per day (TPD). This was accomplished through cold flow simulation of the gasifier quench zone transition region at Coanda and through an extensive hotfire gasifier test program on highly reactive coal and high ash/high ash fusion temperature coals at GTI. RTI matured an advanced water gas shift process and catalyst to readiness for testing at pilot plant scale through catalyst development and testing, and development of a preliminary design basis for a pilot scale reactor demonstrating the catalyst. A techno-economic analysis was performed by Nexant to assess the potential benefits of the gasifier and catalyst technologies in the context of power production and methanol production. This analysis showed an 18%reduction in cost of power and a 19%reduction in cost of methanol relative to DOE reference baseline cases.

  18. Permeability of volcanic rocks to gas and water

    Science.gov (United States)

    Heap, M. J.; Reuschlé, T.; Farquharson, J. I.; Baud, P.

    2018-04-01

    The phase (gas or liquid) of the fluids within a porous volcanic system varies in both time and space. Laboratory experiments have shown that gas and water permeabilities can differ for the same rock sample, but experiments are biased towards rocks that contain minerals that are expected react with the pore fluid (such as the reaction between liquid water and clay). We present here the first study that systematically compares the gas and water permeability of volcanic rocks. Our data show that permeabilities to argon gas and deionised water can differ by a factor between two and five in two volcanic rocks (basalt and andesite) over a confining pressure range from 2 to 50 MPa. We suggest here that the microstructural elements that offer the shortest route through the sample-estimated to have an average radius 0.1-0.5 μm using the Klinkenberg slip factor-are accessible to gas, but restricted or inaccessible to water. We speculate that water adsorption on the surface of these thin microstructural elements, assumed here to be tortuous/rough microcracks, reduces their effective radius and/or prevents access. These data have important implications for fluid flow and therefore the distribution and build-up of pore pressure within volcanic systems.

  19. Sodium-Water Reaction approach and mastering for ASTRID Steam Generator design

    International Nuclear Information System (INIS)

    Saez, Manuel; Allou, Alexandre; Beauchamp, François; Bertrand, Carole; Rodriguez, Gilles; Menou, Sylvain; Prele, Gérard

    2013-01-01

    Conclusions: • Modular Steam Generator concept selected for ASTRID: → Brings flexibility for the expertise of failed modules after their removal; → Intrinsically limit the mechanical consequences of a postulated large Sodium-Water Reaction. • Sodium-Water-Air Reaction studies include both prevention and mitigation aspects, with dedicated tools to be developed through R&D. • Regarding Safety analysis, the possibility to move from the scenario of instantaneous failure of the whole Steam Generator tube bundle toward a scenario with sequenced failure needs to be investigated. • The Steam Generator is one of the key components in the Sodium-cooled Fast Reactor system for it provides an interface between sodium and water. The design objective for the Steam Generator is related to the improvement of mastering of Sodium-Water Reaction. • Potential Sodium-Water Reactions can be eliminated by adopting a Gas based Power Conversion System

  20. Pilot Scale Water Gas Shift - Membrane Device for Hydrogen from Coal

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Tom [Western Research Inst. (WRI), Laramie, WY (United States)

    2013-09-01

    The objectives of the project were to build pilot scale hydrogen separation systems for use in a gasification product stream. This device would demonstrate fabrication and manufacturing techniques for producing commercially ready facilities. The design was a 2 lb/day hydrogen device which included composite hydrogen separation membranes, a water gas shift monolith catalyst, and stainless steel structural components. Synkera Technologies was to prepare hydrogen separation membranes with metallic rims, and to adjust the alloy composition in their membranes to a palladium-gold composition which is sulfur resistant. Chart was to confirm their brazing technology for bonding the metallic rims of the composite membranes to their structural components and design and build the 2 lbs/day device incorporating membranes and catalysts. WRI prepared the catalysts and completed the testing of the membranes and devices on coal derived syngas. The reactor incorporated eighteen 2'' by 7'' composite palladium alloy membranes. These membranes were assembled with three stacks of three paired membranes. Initial vacuum testing and visual inspection indicated that some membranes were cracked, either in transportation or in testing. During replacement of the failed membranes, while pulling a vacuum on the back side of the membranes, folds were formed in the flexible composite membranes. In some instances these folds led to cracks, primarily at the interface between the alumina and the aluminum rim. The design of the 2 lb/day device was compromised by the lack of any membrane isolation. A leak in any membrane failed the entire device. A large number of tests were undertaken to bring the full 2 lb per day hydrogen capacity on line, but no single test lasted more than 48 hours. Subsequent tests to replace the mechanical seals with brazing have been promising, but the technology remains promising but not proven.

  1. Reactions of nitrate salts with ammonia in supercritical water

    International Nuclear Information System (INIS)

    Dell'Orco, P.C.; Gloyna, E.F.; Buelow, S.J.

    1997-01-01

    Reactions involving nitrate salts and ammonia were investigated in supercritical water at temperatures from 450 to 530 C and pressures near 300 bar. Reaction products included nitrite, nitrogen gas, and nitrous oxide. Observed reaction rates and product distributions provided evidence for a free-radical reaction mechanism with NO 2 , NO, and NH 2 · as the primary reactive species at supercritical conditions. In the proposed elementary mechanism, the rate-limiting reaction step was determined to be the hydrolysis of MNO 3 species, which resulted in the formation of nitric acid and subsequently NO 2 . A simple second-order reaction model was used to represent the data. In developing an empirical kinetic model, nitrate and nitrate were lumped as an NO x - reactant. Empirical kinetic parameters were developed for four MNO x /NH 3 reacting systems, assuming first orders in both NH 3 and NO x - . Observed MNO x /NH 3 reaction rates and mechanisms suggest immediately a practical significance of these reactions for nitrogen control strategies in supercritical water oxidation processes

  2. Kinetics of the reaction between H· and superheated water probed with muonium

    International Nuclear Information System (INIS)

    Alcorn, C.; Brodovitch, J.-C.; Ghandi, K.; Kennedy, A.; Percival, P.W.; Smith, M.

    2011-01-01

    Safe operation of a supercritical water cooled reactor requires knowledge of the reaction kinetics of transient species formed by the radiolysis of water in the temperature range 300-650"oC. By using a light isotope of the H·atom, it is possible to study its chemistry in water over this range of temperatures. Arguably, the most important reaction to study is that of the H·atom with the bulk solvent. This reaction could provide an in situ source of H_2 gas, which is added to CANDU reactors to suppress oxidative corrosion. The work described here concerns studies of the reaction of muonium with H_2O and D_2O at temperatures up to 450"oC.

  3. SurfKin: an ab initio kinetic code for modeling surface reactions.

    Science.gov (United States)

    Le, Thong Nguyen-Minh; Liu, Bin; Huynh, Lam K

    2014-10-05

    In this article, we describe a C/C++ program called SurfKin (Surface Kinetics) to construct microkinetic mechanisms for modeling gas-surface reactions. Thermodynamic properties of reaction species are estimated based on density functional theory calculations and statistical mechanics. Rate constants for elementary steps (including adsorption, desorption, and chemical reactions on surfaces) are calculated using the classical collision theory and transition state theory. Methane decomposition and water-gas shift reaction on Ni(111) surface were chosen as test cases to validate the code implementations. The good agreement with literature data suggests this is a powerful tool to facilitate the analysis of complex reactions on surfaces, and thus it helps to effectively construct detailed microkinetic mechanisms for such surface reactions. SurfKin also opens a possibility for designing nanoscale model catalysts. Copyright © 2014 Wiley Periodicals, Inc.

  4. Computational methodology of sodium-water reaction phenomenon in steam generator of sodium-cooled fast reactor

    International Nuclear Information System (INIS)

    Takata, Takashi; Yamaguchi, Akira; Uchibori, Akihiro; Ohshima, Hiroyuki

    2009-01-01

    A new computational methodology of sodium-water reaction (SWR), which occurs in a steam generator of a liquid-sodium-cooled fast reactor when a heat transfer tube in the steam generator fails, has been developed considering multidimensional and multiphysics thermal hydraulics. Two kinds of reaction models are proposed in accordance with a phase of sodium as a reactant. One is the surface reaction model in which water vapor reacts directly with liquid sodium at the interface between the liquid sodium and the water vapor. The reaction heat will lead to a vigorous evaporation of liquid sodium, resulting in a reaction of gas-phase sodium. This is designated as the gas-phase reaction model. These two models are coupled with a multidimensional, multicomponent gas, and multiphase thermal hydraulics simulation method with compressibility (named the 'SERAPHIM' code). Using the present methodology, a numerical investigation of the SWR under a pin-bundle configuration (a benchmark analysis of the SWAT-1R experiment) has been carried out. As a result, the maximum gas temperature of approximately 1,300degC is predicted stably, which lies within the range of previous experimental observations. It is also demonstrated that the maximum temperature of the mass weighted average in the analysis agrees reasonably well with the experimental result measured by thermocouples. The present methodology will be promising to establish a theoretical and mechanical modeling of secondary failure propagation of heat transfer tubes due to such as an overheating rupture and a wastage. (author)

  5. Kinetics of the reaction between H· and superheated water probed with muonium

    Energy Technology Data Exchange (ETDEWEB)

    Alcorn, C. [Mount Allison Univ., Sackville, NB (Canada); Brodovitch, J.-C. [Simon Fraser Univ., Burnaby, BC (Canada); Ghandi, K.; Kennedy, A. [Mount Allison Univ., Sackville, NB (Canada); Percival, P.W. [Simon Fraser Univ., Burnaby, BC (Canada); TRIUMF, Vancouver, BC (Canada); Smith, M. [Mount Allison Univ., Sackville, NB (Canada)

    2011-07-01

    Safe operation of a supercritical water cooled reactor requires knowledge of the reaction kinetics of transient species formed by the radiolysis of water in the temperature range 300-650{sup o}C. By using a light isotope of the H·atom, it is possible to study its chemistry in water over this range of temperatures. Arguably, the most important reaction to study is that of the H·atom with the bulk solvent. This reaction could provide an in situ source of H{sub 2} gas, which is added to CANDU reactors to suppress oxidative corrosion. The work described here concerns studies of the reaction of muonium with H{sub 2}O and D{sub 2}O at temperatures up to 450{sup o}C.

  6. Effect of algae and water on water color shift

    Science.gov (United States)

    Yang, Shengguang; Xia, Daying; Yang, Xiaolong; Zhao, Jun

    1991-03-01

    This study showed that the combined effect of absorption of planktonic algae and water on water color shift can be simulated approximately by the exponential function: Log( E {100cm/ W }+ E {100cm/ Xch1})=0.002λ-2.5 where E {100/cm W }, E {100cm/ Xchl} are, respectively, extinction coefficients of seawater and chlorophyll—a (concentration is equal to X mg/m3), and λ (nm) is wavelength. This empirical regression equation is very useful for forecasting the relation between water color and biomass in water not affected by terrigenous material. The main factor affecting water color shift in the ocean should be the absorption of blue light by planktonic algae.

  7. Sodium-water reaction product flow system

    Energy Technology Data Exchange (ETDEWEB)

    Shirataki, K; Wada, H

    1978-11-18

    Purpose: To provide the subject equipments wherein thermal insulating layers which neither exfoliate nor react by the impact due to high temperature sodium and hydrogen gas and are used for mitigating the thermal impact are provided on the inner surfaces of the emission system equipments, thereby preventing the destruction of the emission system equipments. Constitution: Thermal insulating layers are formed on the inner surfaces of sodium-water reaction product emission system equipments, that is, the inner surface of the emission system pipeline, that of the accommodation vessel and the surface of the cyclone separator, by film treatment, coating or heat resisting coating, and these surfaces are covered with the layers. Each of the layers is made of a material which does not cause a rapid reaction with high temperature sodium or hydrogen gas nor exfoliates and is withstandable for several seconds in which the thermal impact of at least the emission system comes into question, and its thickness is more than one capable of securing the necessary thermal resistance computed by the thermal impact analysis of the emission system.

  8. Sodium-water reaction product flow system

    International Nuclear Information System (INIS)

    Shirataki, Koji; Wada, Hozumi.

    1978-01-01

    Purpose: To provide the subject equipments wherein thermal insulating layers which neither exfoliate nor react by the impact due to high temperature sodium and hydrogen gas and are used for mitigating the thermal impact are provided on the inner surfaces of the emission system equipments, thereby preventing the destruction of the emission system equipments. Constitution: Thermal insulating layers are formed on the inner surfaces of sodium-water reaction product emission system equipments, that is, the inner surface of the emission system pipeline, that of the accommodation vessel and the surface of the cyclone separator, by film treatment, coating or heat resisting coating, and these surfaces are covered with the layers. Each of the layers is made of a material which does not cause a rapid reaction with high temperature sodium or hydrogen gas nor exfoliates and is withstandable for several seconds in which the thermal impact of at least the emission system comes into question, and its thickness is more than one capable of securing the necessary thermal resistance computed by the thermal impact analysis of the emission system. (Yoshihara, H.)

  9. Humidity independent mass spectrometry for gas phase chemical analysis via ambient proton transfer reaction.

    Science.gov (United States)

    Zhu, Hongying; Huang, Guangming

    2015-03-31

    In this work, a humidity independent mass spectrometric method was developed for rapid analysis of gas phase chemicals. This method is based upon ambient proton transfer reaction between gas phase chemicals and charged water droplets, in a reaction chamber with nearly saturate humidity under atmospheric pressure. The humidity independent nature enables direct and rapid analysis of raw gas phase samples, avoiding time- and sample-consuming sample pretreatments in conventional mass spectrometry methods to control sample humidity. Acetone, benzene, toluene, ethylbenzene and meta-xylene were used to evaluate the analytical performance of present method. The limits of detection for benzene, toluene, ethylbenzene and meta-xylene are in the range of ∼0.1 to ∼0.3 ppbV; that of benzene is well below the present European Union permissible exposure limit for benzene vapor (5 μg m(-3), ∼1.44 ppbV), with linear ranges of approximately two orders of magnitude. The majority of the homemade device contains a stainless steel tube as reaction chamber and an ultrasonic humidifier as the source of charged water droplets, which makes this cheap device easy to assemble and facile to operate. In addition, potential application of this method was illustrated by the real time identification of raw gas phase chemicals released from plants at different physiological stages. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. The Gas-Absorption/Chemical-Reaction Method for Measuring Air-Water Interfacial Area in Natural Porous Media

    Science.gov (United States)

    Lyu, Ying; Brusseau, Mark L.; El Ouni, Asma; Araujo, Juliana B.; Su, Xiaosi

    2017-11-01

    The gas-absorption/chemical-reaction (GACR) method used in chemical engineering to quantify gas-liquid interfacial area in reactor systems is adapted for the first time to measure the effective air-water interfacial area of natural porous media. Experiments were conducted with the GACR method, and two standard methods (X-ray microtomographic imaging and interfacial partitioning tracer tests) for comparison, using model glass beads and a natural sand. The results of a series of experiments conducted under identical conditions demonstrated that the GACR method exhibited excellent repeatability for measurement of interfacial area (Aia). Coefficients of variation for Aia were 3.5% for the glass beads and 11% for the sand. Extrapolated maximum interfacial areas (Am) obtained with the GACR method were statistically identical to independent measures of the specific solid surface areas of the media. For example, the Am for the glass beads is 29 (±1) cm-1, compared to 32 (±3), 30 (±2), and 31 (±2) cm-1 determined from geometric calculation, N2/BET measurement, and microtomographic measurement, respectively. This indicates that the method produced accurate measures of interfacial area. Interfacial areas determined with the GACR method were similar to those obtained with the standard methods. For example, Aias of 47 and 44 cm-1 were measured with the GACR and XMT methods, respectively, for the sand at a water saturation of 0.57. The results of the study indicate that the GACR method is a viable alternative for measuring air-water interfacial areas. The method is relatively quick, inexpensive, and requires no specialized instrumentation compared to the standard methods.

  11. Reactions of plutonium and uranium with water: Kinetics and potential hazards

    International Nuclear Information System (INIS)

    Haschke, J.M.

    1995-12-01

    The chemistry and kinetics of reactions between water and the metals and hydrides of plutonium and uranium are described in an effort to consolidate information for assessing potential hazards associated with handling and storage. New experimental results and data from literature sources are presented. Kinetic dependencies on pH, salt concentration, temperature and other parameters are reviewed. Corrosion reactions of the metals in near-neutral solutions produce a fine hydridic powder plus hydrogen. The corrosion rate for plutonium in sea water is a thousand-fold faster than for the metal in distilled water and more than a thousand-fold faster than for uranium in sea water. Reaction rates for immersed hydrides of plutonium and uranium are comparable and slower than the corrosion rates for the respective metals. However, uranium trihydride is reported to react violently if a quantity greater than twenty-five grams is rapidly immersed in water. The possibility of a similar autothermic reaction for large quantities of plutonium hydride cannot be excluded. In addition to producing hydrogen, corrosion reactions convert the massive metals into material forms that are readily suspended in water and that are aerosolizable and potentially pyrophoric when dry. Potential hazards associated with criticality, environmental dispersal, spontaneous ignition and explosive gas mixtures are outlined

  12. Gas and Water Permeability of Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Villar, M. V.; Martin, P. L.; Romero, F. J.; Gutierrez-Rodirgo, V.; Barcala, J. M.

    2012-11-01

    The gas pressure of concrete samples was measured in an unsteady-state equipment working under low injection pressures and in a newly fine tuned steady-state setup working under different pressures. These measurements allowed the estimation of the intrinsic and relative gas permeability of the concrete and of the effect of boundary conditions on them. Permeability decreased with water content, but it was also greatly affected by the hydraulic history of concrete, i.e. if it had been previously dried or wetted. In particular, and for a given degree of saturation, the gas permeability of concrete previously saturated was lower than if the concrete had been just air dried or saturated after air drying. In any case, the gas permeability was about two orders of magnitude higher than the liquid water permeability (10-16 vs. 10-18 m2), probably due to the chemical reactions taking place during saturation (carbonation). The relative gas permeability of concrete increased sharply for water degrees of saturation smaller than 50%. The boundary conditions also affected the gas permeability, which seemed to be mostly conditioned by the back pressure and the confining pressure, increasing as the former increased and decreasing as the latter increased, i.e. decreasing as the effective pressure increased. Overall the increase of pressure head or injection pressure implied a decrease in gas permeability. External,microcracking during air-drying could not be ruled out as responsible for the decrease of permeability with confining pressure. The apparent permeability obtained applying the Klinkenberg method for a given effective pressure was only slightly smaller than the average of all the values measured for the same confining pressure range. For this reason it is considered that the Klinkenberg effect was not relevant in the range of pressures applied. (Author) 37 refs.

  13. Solid gas reaction phase diagram under high gas pressure

    International Nuclear Information System (INIS)

    Ishizaki, K.

    1992-01-01

    This paper reports that to evaluate which are the stable phases under high gas pressure conditions, a solid-gas reaction phase diagram under high gas pressure (HIP phase diagram) has been proposed by the author. The variables of the diagram are temperature, reactant gas partial pressure and total gas pressure. Up to the present time the diagrams have been constructed using isobaric conditions. In this work, the stable phases for a real HIP process were evaluated assuming an isochoric condition. To understand the effect of the total gas pressure on stability is of primary importance. Two possibilities were considered and evaluated, those are: the total gas pressure acts as an independent variable, or it only affects the fugacity values. The results of this work indicate that the total gas pressure acts as an independent variable, and in turn also affects the fugacity values

  14. Electron scattering in dense He-Ar gas mixtures: A pressure shift study

    International Nuclear Information System (INIS)

    Asaf, U.; Felps, W.S.; McGlynn, S.P.

    1989-01-01

    The dependence of the energies of high-n Rydberg states of CH 3 I on the molar composition of helium-argon mixtures (in the number density range 1.3x10 20 --5.6x10 20 cm -3 ) is reported. The energy shifts, when normalized to a given density value, are found to vary linearly with the mole fraction of either component of the binary, rare-gas mixture. The observed change in sign of the energy shift is attributable to the different signs of the electron scattering lengths for the two rare-gas components. As a result, there exists a mixture composition, at a mole ratio [He]/[Ar]=2.0, at which the shift is null. The experimental results for the gas mixture agree with the Fermi formula, as modified to include the Alekseev-Sobel'man polarization term. Effective electron scattering lengths and cross sections, polarizabilities, and thermal velocities are used to characterize the effects of the binary gas perturber system

  15. Chemical recycling of carbon dioxide emissions from a cement plant into dimethyl ether, a case study of an integrated process in France using a Reverse Water Gas Shift (RWGS) step

    International Nuclear Information System (INIS)

    Vibhatavata, Phuangphet; Borgard, Jean-Marc; Tabarant, Michel; Bianchi, Daniel; Mansilla, Christine

    2013-01-01

    Recycling of carbon dioxide (CO 2 ) and hydrogen (H 2 ) into liquid fuel technology has recently gained wide public interest since it is a potential pathway to increase the liquid fuel supply and to mitigate CO 2 emissions simultaneously. In France, the majority of the electricity production is derived from nuclear and renewable energy which have a low CO 2 footprint. This electricity power enables a potential for massive hydrogen production with low carbon emissions. We studied the possibility to develop this technology at an industrial scale in the French context on a typical industrial example of a cement manufacture in the south of France. An integrated process is proposed, which enables the use of the heat released by the CO 2 to fuel process to help to capture the CO 2 released by the cement manufacture. Some technological issues are discussed, and a potential solution is proposed for the catalyst used in the critical step of the Reverse Water Gas-Shift reaction (RWGS) of the process. (authors)

  16. In situ TEM observation of solid-gas reactions

    International Nuclear Information System (INIS)

    Kishita, K; Kamino, T; Watabe, A; Kuroda, K; Saka, H

    2008-01-01

    Under a gaseous atmosphere at high temperatures, almost all the materials (metal, catalysts, etc.) change their structures and properties. For the research and development of materials, it is of vital importance to clarify mechanisms of solid-gas and liquid-gas reactions. Recently an in situ TEM system combined with an environmental holder, which has a gas injection nozzle close to a specimen-heating element, has been developed. The gas injection nozzle permits gas to flow around the specimens sitting on the heating element made of a fine W filament. The newly developed in situ TEM has a differential pumping system; therefore, the pressure in the specimen chamber is maintained in the range of higher than 1 Pa, while the pressure in the electron gun chamber can be kept in the range of 10 -5 Pa. This system was applied to in situ observation of chemical reactions of metals with gases: Observation of oxidation and reduction under a gas pressure ranging from 10 -5 Pa to 1 Pa at high temperatures (room temperature to ∼1473 K) were successfully carried out on pure metal and rare metal catalysts at near-atomic resolution. This in situ environmental TEM system is promising for clarifying mechanisms of many solid-gas and liquid-gas reactions that take place at high temperatures under a gas atmosphere.

  17. Effect of the kind of fuel in the synthesis of the catalyzer NiFe{sub 2}O{sub 4} to displacement reaction of water gas (WGRS); Efeito do tipo de combustivel na sintese do catalisador NiFe{sub 2}O{sub 4} para reacao de deslocamento do gas agua (WGRS)

    Energy Technology Data Exchange (ETDEWEB)

    Santos, P.T.A.; Barros, B.S.; Costa, A.C.F.M.; Gama, L. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais], e-mail: anacristina@dema.ufcg.edu.br; Jesus, A.A.; Andrade, H.M.C. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica

    2006-07-01

    This work has as objective synthesizes and to characterize the NiFe{sub 2}O{sub 4} catalyst by combustion reaction using different fuels: urea and glycine seeking your application in the water gas shift reaction (WGSR), promoting the purification of the methane for the elimination of the carbon monoxide. The powders were prepared in agreement with the chemistry of the propellants using as recipient a vitreous silica crucible; the maximum temperature and the medium time of flame were verified. The powders were characterized by X-ray diffraction (DRX), Scanning electronic microscopy and catalytic tests. The results show that the catalysts presented inverse spinel structure as majority phase for the two types of fuels. However, it was observed that using the urea, there was the presence of a second phase of NiO and when the glycine was used, there was the presence of lines of Ni. The catalyst NiFe{sub 2}O{sub 4} using urea as fuel, presented better catalytic acting. (author)

  18. Impact of the spatial distribution of morphological pattern on the efficiency of electrocatalytic gas evolving reactions

    Directory of Open Access Journals (Sweden)

    Žerađanin Aleksandar R.

    2014-01-01

    Full Text Available The efficiency of electrocatalytic gas evolving reactions (hydrogen, chlorine and oxygen evolution is a key challenge for the important industrial processes, such as chlor-alkali electrolysis or water electrolysis. Central issue for the aforementioned electrocatalytic processes is huge power consumption. Experimental results accumulated in the past, as well as some predictive models ("volcano" plots indicate that altering the nature of the electrode material cannot significantly increase the activity of mentioned reactions. Consequently, it is necessary to find a qualitatively different strategy for improving the energy efficiency of electrocatalytic gas evolving reactions. Usually disregarded fact is that the gas evolution is an oscillatory phenomenon. Given the oscillatory behavior, a key parameter of macrokinetics of gas electrode is the frequency of gas-bubble detachment. Bearing in mind that the gas evolution greatly depends on the surface morphology, a methodology is proposed that establishes a rational link between the morphological pattern of electrode with electrode activity and stability. Characterization was performed using advanced analytical tools. Frequency of gas-bubble detachment is obtained in the configuration of scanning electrochemical microscopy (SECM while the corrosion stability is analyzed using miniaturized scanning flow electrochemical cell connected to the mass spectrometer (SFC-ICPMS.

  19. The Influence of Mixing in High Temperature Gas Phase Reactions

    DEFF Research Database (Denmark)

    Østberg, Martin

    1996-01-01

    by injection of NH3 with carrier gas into the flue gas. NH3 can react with NO and form N2, but a competing reaction path is the oxidation of NH3 to NO.The SNR process is briefly described and it is shown by chemical kinetic modelling that OH radicals under the present conditions will initiate the reaction......The objective of this thesis is to describe the mixing in high temperature gas phase reactions.The Selective Non-Catalytic Reduction of NOx (referred as the SNR process) using NH3 as reductant was chosen as reaction system. This in-furnace denitrification process is made at around 1200 - 1300 K...... diffusion. The SNR process is simulated using the mixing model and an empirical kinetic model based on laboratory experiments.A bench scale reactor set-up has been built using a natural gas burner to provide the main reaction gas. The set-up has been used to perform an experimental investigation...

  20. Effects of solvation shells and cluster size on the reaction of aluminum clusters with water

    Directory of Open Access Journals (Sweden)

    Weiwei Mou

    2011-12-01

    Full Text Available Reaction of aluminum clusters, Aln (n = 16, 17 and 18, with liquid water is investigated using quantum molecular dynamics simulations, which show rapid production of hydrogen molecules assisted by proton transfer along a chain of hydrogen bonds (H-bonds between water molecules, i.e. Grotthuss mechanism. The simulation results provide answers to two unsolved questions: (1 What is the role of a solvation shell formed by non-reacting H-bonds surrounding the H-bond chain; and (2 whether the high size-selectivity observed in gas-phase Aln-water reaction persists in liquid phase? First, the solvation shell is found to play a crucial role in facilitating proton transfer and hence H2 production. Namely, it greatly modifies the energy barrier, generally to much lower values (< 0.1 eV. Second, we find that H2 production by Aln in liquid water does not depend strongly on the cluster size, in contrast to the existence of magic numbers in gas-phase reaction. This paper elucidates atomistic mechanisms underlying these observations.

  1. The Impact of a Rigorous Multiple Work Shift Schedule and Day Versus Night Shift Work on Reaction Time and Balance Performance in Female Nurses: A Repeated Measures Study.

    Science.gov (United States)

    Thompson, Brennan J; Stock, Matt S; Banuelas, Victoria K; Akalonu, Chibuzo C

    2016-07-01

    The aim of this study was to determine the impact of a demanding work schedule involving long, cumulative work shifts on response time and balance-related performance outcomes and to evaluate the prevalence of musculoskeletal disorders between day and night shift working nurses. A questionnaire was used to identify the prevalence of past (12-month) and current (7-day) musculoskeletal disorders. Nurses worked three 12-hour work shifts in a 4-day period. Reaction time and balance tests were conducted before and after the work period. The work period induced impairments for reaction time, errors on reaction time tasks, and balance performance, independent of shift type. Musculoskeletal symptom prevalence was high in workers of both work shifts. Compressed work shifts caused performance-based fatigue in nurses. Reaction time and balance tests may be sensitive fatigue identification markers in nurses.

  2. Comparison of Iran Power Plants Air Pollutants Before and After Shifting to Natural Gas

    Directory of Open Access Journals (Sweden)

    M Ghiasseddin

    2004-07-01

    Full Text Available In a three years period, 24 fossil fueled thermal power plants located in different parts of the country were extensively examined for discharge of pollutants into the environment and their potential effects on surrounding. During this investigation emission to air, discharge to receiving waters and land as well as electromagnetic fields were measured using relevant standard methods. This paper will focus on air pollution emissions and recent reinvestigation that was done after shifting the fuel from residual oil to natural gas. In our first studies that most of the plants were consuming residual oil, high level of SO2 emission in some areas was the main cause of losses to vegetations and fruit gardens. It was concluded that a serious problem threats the environment and health of people living near these areas. Based on the results some mitigation plans were recommended to the authorities, and after some times they started to shift to natural gas consumption. Our recent investigation that was after this action, showed a good improvement of air pollution reduction. This was almost 100% for SO2 and from 32 to 73% for NOx.

  3. Improvement on reaction model for sodium-water reaction jet code and application analysis

    International Nuclear Information System (INIS)

    Itooka, Satoshi; Saito, Yoshinori; Okabe, Ayao; Fujimata, Kazuhiro; Murata, Shuuichi

    2000-03-01

    In selecting the reasonable DBL on steam generator (SG), it is necessary to improve analytical method for estimating the sodium temperature on failure propagation due to overheating. Improvement on sodium-water reaction (SWR) jet code (LEAP-JET ver.1.30) and application analysis to the water injection tests for confirmation of code propriety were performed. On the improvement of the code, a gas-liquid interface area density model was introduced to develop a chemical reaction model with a little dependence on calculation mesh size. The test calculation using the improved code (LEAP-JET ver.1.40) were carried out with conditions of the SWAT-3·Run-19 test and an actual scale SG. It is confirmed that the SWR jet behavior on the results and the influence to analysis result of a model are reasonable. For the application analysis to the water injection tests, water injection behavior and SWR jet behavior analyses on the new SWAT-1 (SWAT-1R) and SWAT-3 (SWAT-3R) tests were performed using the LEAP-BLOW code and the LEAP-JET code. In the application analysis of the LEAP-BLOW code, parameter survey study was performed. As the results, the condition of the injection nozzle diameter needed to simulate the water leak rate was confirmed. In the application analysis of the LEAP-JET code, temperature behavior of the SWR jet was investigated. (author)

  4. Spectral shift rod for the boiling water reactor

    International Nuclear Information System (INIS)

    Yokomizo, O.; Kashiwai, S.; Nishida, K.; Orii, A.; Yamashita, J.; Mochida, T.

    1993-01-01

    A Boiling Water Reactor core concept has been proposed using a new fuel component called spectral shift rod (SSR). The SSR is a new type of water rod in which a water level is formed during core operation. The water level can be controlled by the core recirculation flow rate. By using SSRs, the reactor can be operated with all control rods withdrawn through the operation cycle as well as that a much larger natural uranium saving is possible due to spectral shift operation than in current BWRs. The steady state and transient characteristics of the SSRs have been examined by experiments and analyses to certify the feasibility. In a reference design, a four times larger spectral shift width as for the current BWR has been obtained. (orig.)

  5. Direct observation of an isopolyhalomethane O-H insertion reaction with water: Picosecond time-resolved resonance Raman (ps-TR3) study of the isobromoform reaction with water to produce a CHBr2OH product

    International Nuclear Information System (INIS)

    Kwok, W.M.; Zhao Cunyuan; Li Yunliang; Guan Xiangguo; Phillips, David Lee

    2004-01-01

    Picosecond time-resolved resonance Raman (ps-TR 3 ) spectroscopy was used to obtain the first definitive spectroscopic observation of an isopolyhalomethane O-H insertion reaction with water. The ps-TR 3 spectra show that isobromoform is produced within several picoseconds after photolysis of CHBr 3 and then reacts on the hundreds of picosecond time scale with water to produce a CHBr 2 OH reaction product. Photolysis of low concentrations of bromoform in aqueous solution resulted in noticeable formation of HBr strong acid. Ab initio calculations show that isobromoform can react with water to produce a CHBr 2 (OH) O-H insertion reaction product and a HBr leaving group. This is consistent with both the ps-TR 3 experiments that observe the reaction of isobromoform with water to form a CHBr 2 (OH) product and photolysis experiments that show HBr acid formation. We briefly discuss the implications of these results for the phase dependent behavior of polyhalomethane photochemistry in the gas phase versus water solvated environments

  6. Reaction of a phospholipid monolayer with gas-phase ozone at the air-water interface: measurement of surface excess and surface pressure in real time.

    Science.gov (United States)

    Thompson, Katherine C; Rennie, Adrian R; King, Martin D; Hardman, Samantha J O; Lucas, Claire O M; Pfrang, Christian; Hughes, Brian R; Hughes, Arwel V

    2010-11-16

    The reaction between gas-phase ozone and monolayers of the unsaturated lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC, on aqueous solutions has been studied in real time using neutron reflection and surface pressure measurements. The reaction between ozone and lung surfactant, which contains POPC, leads to decreased pulmonary function, but little is known about the changes that occur to the interfacial material as a result of oxidation. The results reveal that the initial reaction of ozone with POPC leads to a rapid increase in surface pressure followed by a slow decrease to very low values. The neutron reflection measurements, performed on an isotopologue of POPC with a selectively deuterated palmitoyl strand, reveal that the reaction leads to loss of this strand from the air-water interface, suggesting either solubilization of the product lipid or degradation of the palmitoyl strand by a reactive species. Reactions of (1)H-POPC on D(2)O reveal that the headgroup region of the lipids in aqueous solution is not dramatically perturbed by the reaction of POPC monolayers with ozone supporting degradation of the palmitoyl strand rather than solubilization. The results are consistent with the reaction of ozone with the oleoyl strand of POPC at the air-water interface leading to the formation of OH radicals. The highly reactive OH radicals produced can then go on to react with the saturated palmitoyl strands leading to the formation of oxidized lipids with shorter alkyl tails.

  7. Bond-selective control of a gas-surface reaction

    Science.gov (United States)

    Killelea, Daniel R.

    The prospect of using light to selectively control chemical reactions has tantalized chemists since the development of the laser. Unfortunately, the realization of laser-directed chemistry is frequently thwarted by the randomization of energy within the molecule through intramolecular vibrational energy distribution (IVR). However, recent results showing vibrational mode-specific reactivity on metal surfaces suggest that IVR may not always be complete for gas-surface reactions. Here, we combine molecular beam techniques and direct laser excitation to characterize the bond-specific reactivity of trideuteromethane on a Ni(111) surface. Our results reveal important details about how vibrational energy is distributed in the reactive molecule. We use a molecular beam to direct state-selected trideuteromethane (CHD 3) molecules onto a nickel single crystal sample and use the results we obtain to describe the flow of vibrational energy in the methane-surface reaction complex. We show that CHD3 molecules initially excited to v=1, J=2, K=0 of the v 1 symmetric C-H stretching mode will dissociate exclusively via C-H cleavage on Ni(111). This result highlights the localization of vibrational energy in the reaction complex, despite the presence of many energy exchange channels with the high state-density surface. We demonstrate, for the first time, highly parallel bond-selective control of a heterogeneously catalyzed reaction. We place our results in the context of recent experiments investigating IVR for molecules in both the gas phase and liquid solutions. If IVR is fast on the reaction timescale, vibrational energy would be randomly distributed throughout the nascent methane-surface reaction complex and vibrational mode-specific behavior would not occur. The short timescale of a direct gas-surface collision may explain how the exchange of energy via IVR is limited to only a small subset of the energetic configurations available to the reaction complex. This framework

  8. Design of the US-CRBRP sodium/water reaction pressure relief system

    International Nuclear Information System (INIS)

    Kruger, G.B.; Murdock, T.B.; Rodwell, E.; Sane, J.O.

    1976-01-01

    Protection against intermediate sodium system overpressure from the sodium/water reaction associated with large leaks within the CRBRP Steam Generators is provided by the sodium/water reaction pressure relief system (SWRPRS). This system consists of rupture disks connected to the intermediate sodium piping adjacent to the inlet to the superheater and outlet from the evaporator modules. The rupture discs relieve into piping that leads to reaction produce separator tanks, which in turn are vented to a centrifugal separator and flare stack arranged to burn hydrogen gas exhausting into the atmosphere. Analyses have been conducted using the TRANSWRAP Computer Code to predict the system pressures and flow rates during the large leak event. Experimental tests to be conducted in the large leak test rig (LLTR) will be used to confirm the analysis techniques used in the design

  9. Electron stimulated reactions of methyl iodide coadsorbed with amorphous solid water

    International Nuclear Information System (INIS)

    Perry, C. C.; Faradzhev, N. S.; Madey, T. E.; Fairbrother, D. H.

    2007-01-01

    The electron stimulated reactions of methyl iodide (MeI) adsorbed on and suspended within amorphous solid water (ice) were studied using a combination of postirradiation temperature programmed desorption and reflection absorption infrared spectroscopy. For MeI adsorbed on top of amorphous solid water (ice), electron beam irradiation is responsible for both structural and chemical transformations within the overlayer. Electron stimulated reactions of MeI result principally in the formation of methyl radicals and solvated iodide anions. The cross section for electron stimulated decomposition of MeI is comparable to the gas phase value and is only weakly dependent upon the local environment. For both adsorbed MeI and suspended MeI, reactions of methyl radicals within MeI clusters lead to the formation of ethane, ethyl iodide, and diiodomethane. In contrast, reactions between the products of methyl iodide and water dissociation are responsible for the formation of methanol and carbon dioxide. Methane, formed as a result of reactions between methyl radicals and either parent MeI molecules or hydrogen atoms, is also observed. The product distribution is found to depend on the film's initial chemical composition as well as the electron fluence. Results from this study highlight the similarities in the carbon-containing products formed when monohalomethanes coadsorbed with amorphous solid water are irradiated by either electrons or photons

  10. Electronic shift register memory based on molecular electron-transfer reactions

    Science.gov (United States)

    Hopfield, J. J.; Onuchic, Jose Nelson; Beratan, David N.

    1989-01-01

    The design of a shift register memory at the molecular level is described in detail. The memory elements are based on a chain of electron-transfer molecules incorporated on a very large scale integrated (VLSI) substrate, and the information is shifted by photoinduced electron-transfer reactions. The design requirements for such a system are discussed, and several realistic strategies for synthesizing these systems are presented. The immediate advantage of such a hybrid molecular/VLSI device would arise from the possible information storage density. The prospect of considerable savings of energy per bit processed also exists. This molecular shift register memory element design solves the conceptual problems associated with integrating molecular size components with larger (micron) size features on a chip.

  11. Membrane Bioreactor (MBR) as Alternative to a Conventional Activated Sludge System Followed by Ultrafiltration (CAS-UF) for the Treatment of Fischer-Tropsch Reaction Water from Gas-to-Liquids Industries

    NARCIS (Netherlands)

    Laurinonyte, Judita; Meulepas, Roel J.W.; Brink, van den Paula; Temmink, Hardy

    2017-01-01

    The potential of a membrane bioreactor (MBR) system to treat Fischer-Tropsch (FT) reaction water from gas-to-liquids (GTL) industries was investigated and compared with the current treatment system: a conventional activated sludge system followed by an ultrafiltration (CAS-UF) unit. The MBR and

  12. Electrodeposition of Ni-Mo alloy coatings for water splitting reaction

    Science.gov (United States)

    Shetty, Akshatha R.; Hegde, Ampar Chitharanjan

    2018-04-01

    The present study reports the development of Ni-Mo alloy coatings for water splitting applications, using a citrate bath the inducing effect of Mo (reluctant metal) on electrodeposition, its relationship with their electrocatalytic efficiency were studied. The alkaline water splitting efficiency of Ni-Mo alloy coatings, for both hydrogen evolution reaction (HER) and oxygen evolution reaction were tested using cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. Moreover, the practical utility of these electrode materials were evaluated by measuring the amount of H2 and O2 gas evolved. The variation in electrocatalytic activity with composition, structure, and morphology of the coatings were examined using XRD, SEM, and EDS analyses. The experimental results showed that Ni-Mo alloy coating is the best electrode material for alkaline HER and OER reactions, at lower and higher deposition current densities (c. d.'s) respectively. This behavior is attributed by decreased Mo and increased Ni content of the alloy coating and the number of electroactive centers.

  13. Water recovery from flue gas

    Energy Technology Data Exchange (ETDEWEB)

    Heijboer, R.; Van Deelen-Bremer, M.H.; de Vos, F.; Zeijseink, A.G.L. [KEMA Nederland B.V. (Netherlands)

    2007-07-01

    In the power generation process a large amount of water is needed, for steam generation, flue gas cleaning etc. On the other hand a large amount of water is emitted to the atmosphere via the stack. For example a 400 MW coal fired power plant with a flue gas desulfurisation plant emits about 1,500,000 m{sup 3} per hour with a water concentration of about 11%. The emitted water has a rather good quality compared to surface water and needs less effort to be treated for use as make-up water. As the available amount of water in the flue gas from the earlier mentioned power plant is about 150 tons per hour, recovering 20% of this amount covers the make-up water needs of this 400 MW power plant. Direct condensation of the flue gas needs large cooling power and the condensed water is acidic and corrosive and needs cleanup treatment before it can be used in the water/steam cycle. KEMA developed a technology based on gas separation membranes which makes it possible to recover water from flue gas. The process is covered by a wide patent. The principle of the membrane is comparable to the material that is used in fabric like SympaTex{reg_sign} and GORE-TEX{reg_sign}. The GORE-TEX material is permeable to water vapor but rejects liquid water. The driving force is the water vapor pressure close to the human skin which is the higher than the water vapor pressure open the outside of the clothing. The selectivity of the GORE-TEX material however is not good enough to be used at the temperature of flue gas. The University of Twente (Netherlands) developed a membrane material based on modified PEEK which is highly selective of water vapor at flue gas temperatures. Based on the fact that flat membranes have an uneconomical surface to volume ratio, the choice has been made to use hollow fibre membranes. 6 figs.

  14. Experimental and numerical reaction analysis on sodium-water chemical reaction field

    International Nuclear Information System (INIS)

    Deguchi, Yoshihiro; Takata, Takashi; Yamaguchi, Akira; Kikuchi, Shin; Ohshima, Hiroyuki

    2015-01-01

    In a sodium-cooled fast reactor (SFR), liquid sodium is used as a heat transfer fluid because of its excellent heat transport capability. On the other hand, it has strong chemical reactivity with water vapor. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow by a breach of heat transfer tubes. This process ends up damages on the heat transport equipment in the SFR. Therefore, the study on sodium-water chemical reactions is of paramount importance for security reasons. This study aims to clarify the sodium-water reaction mechanisms using an elementary reaction analysis. A quasi one-dimensional flame model is applied to a sodium-water counter-flow reaction field. The analysis contains 25 elementary reactions, which consist of 17 H_2-O_2 and 8 Na-H_2O reactions. Temperature and species concentrations in the counter-flow reaction field were measured using laser diagnostics such as LIF and CARS. The main reaction in the experimental conditions is Na+H_2O → NaOH+H and OH is produced by H_2O+H → H_2+OH. It is demonstrated that the reaction model in this study well explains the structure of the sodium-water counter-flow diffusion flame. (author)

  15. Coating of graphite flakes with MgO/carbon nanocomposite via gas state reaction

    International Nuclear Information System (INIS)

    Sharif, M.; Faghihi-Sani, M.A.; Golestani-Fard, F.; Saberi, A.; Soltani, Ali Khalife

    2010-01-01

    Coating of graphite flakes with MgO/carbon nanocomposite was carried out via gaseous state reaction between mixture of Mg metal, CO gas and graphite flakes at 1000 o C. XRD and FE-SEM analysis of coating showed that the coating was comprised of MgO nano particles and amorphous carbon distributed smoothly and covered the graphite surface evenly. Thermodynamic calculations were employed to predict the reaction sequences as well as phase stability. The effect of coating on water wettability and oxidation resistance of graphite was studied using contact angle measurement and TG analysis, respectively. It was demonstrated that the reaction between Mg and CO could result in MgO/C nanocomposite deposition. The coating improved water wettability of graphite and also enhanced the oxidation resistance of graphite flakes significantly. Also the graphite coating showed significant phenolic resin-wettabilty owing to high surface area of such hydrophilic nano composite coating. The importance of graphite coating is explained with emphasis on its potential application in graphite containing refractories.

  16. The exchange reaction between deuterium and water vapour on platinum deposited over a hydrophobic support

    International Nuclear Information System (INIS)

    Itsuo, Iida; Junko, Kato; Kenzi, Tamuru

    1977-01-01

    Isotope exchange reaction between deuterium gas and water vapour at room temperature and below on platinum deposited on hydrophobic supports such as polytetrafluoroethylene (PTFE) or Porapak Q (copolymer of styrene and divinylbenzene) was studied and the results were compared with those of the exchange reaction on platinum over hydrophilic support such as alumina. It was demonstrated that the exchange reaction at temperatures below the boiling point of water is markedly retarded by the multilayer adsorption of water over the platinum catalyst deposited on hydrophilic support, whereas the platinum catalyst on hydrophobic support exhibited a high catalytic activity, being not retarded by the water, forming no multilayer of adsorbed water over platinum surface. Therefore in the case of the hydrogen isotope exchange reaction on platinum over hydrophobic support, the chemical exchange rate can be measured even under a saturated vapour pressure of water. The surface area of platinum was estimated by hydrogen chemisorption and hydrogen titration and specific activities of the catalyst were calculated at both room temperature and freezing point of water, which revealed that the specific rate of this reaction does not differ so much over various supports. (orig.) [de

  17. Life cycle water consumption for shale gas and conventional natural gas.

    Science.gov (United States)

    Clark, Corrie E; Horner, Robert M; Harto, Christopher B

    2013-10-15

    Shale gas production represents a large potential source of natural gas for the nation. The scale and rapid growth in shale gas development underscore the need to better understand its environmental implications, including water consumption. This study estimates the water consumed over the life cycle of conventional and shale gas production, accounting for the different stages of production and for flowback water reuse (in the case of shale gas). This study finds that shale gas consumes more water over its life cycle (13-37 L/GJ) than conventional natural gas consumes (9.3-9.6 L/GJ). However, when used as a transportation fuel, shale gas consumes significantly less water than other transportation fuels. When used for electricity generation, the combustion of shale gas adds incrementally to the overall water consumption compared to conventional natural gas. The impact of fuel production, however, is small relative to that of power plant operations. The type of power plant where the natural gas is utilized is far more important than the source of the natural gas.

  18. Fundamental studies on the reaction process of partial hydropyrolysis of coal

    Energy Technology Data Exchange (ETDEWEB)

    O. Yamada; H. Yasuda; M. Kaiho [National Institute of Advanced Industrial Science and Technology, Ibaraki (Japan). Energy Technology Research Institute

    2005-07-01

    In order to make up a simulator to support the development of coal partial hydropyrolysis process, material balance of the reaction was investigated precisely. Amount of H{sub 2} evolved by pyrolysis under inert gas atmosphere was found almost equal to that of (CO+2CO{sub 2}), therefore, most of H{sub 2} seemed to be generated through water gas reaction and shift reaction. CH{sub 4} seemed to be stable even at 1073K and 7.1MPa of H{sub 2}, its generation was simply accelerated in proportion to H{sub 2} pressure. Hydrocarbons, other than CH{sub 4}, were fundamentally unstable at 1073K and 0.93 -7.1MPa of H{sub 2}, however the rate of decomposition of them were so slow that amounts of them evolved were apparently proportion to reaction time and H{sub 2} pressure. BTX and naphthalene were increased apparently with H{sub 2} pressure when the reaction time was less than 5s. 4 refs., 20 figs.

  19. Reaction kinetics of cellulose hydrolysis in subcritical and supercritical water

    Science.gov (United States)

    Olanrewaju, Kazeem Bode

    The uncertainties in the continuous supply of fossil fuels from the crisis-ridden oil-rich region of the world is fast shifting focus on the need to utilize cellulosic biomass and develop more efficient technologies for its conversion to fuels and chemicals. One such technology is the rapid degradation of cellulose in supercritical water without the need for an enzyme or inorganic catalyst such as acid. This project focused on the study of reaction kinetics of cellulose hydrolysis in subcritical and supercritical water. Cellulose reactions at hydrothermal conditions can proceed via the homogeneous route involving dissolution and hydrolysis or the heterogeneous path of surface hydrolysis. The work is divided into three main parts. First, the detailed kinetic analysis of cellulose reactions in micro- and tubular reactors was conducted. Reaction kinetics models were applied, and kinetics parameters at both subcritical and supercritical conditions were evaluated. The second major task was the evaluation of yields of water soluble hydrolysates obtained from the hydrolysis of cellulose and starch in hydrothermal reactors. Lastly, changes in molecular weight distribution due to hydrothermolytic degradation of cellulose were investigated. These changes were also simulated based on different modes of scission, and the pattern generated from simulation was compared with the distribution pattern from experiments. For a better understanding of the reaction kinetics of cellulose in subcritical and supercritical water, a series of reactions was conducted in the microreactor. Hydrolysis of cellulose was performed at subcritical temperatures ranging from 270 to 340 °C (tau = 0.40--0.88 s). For the dissolution of cellulose, the reaction was conducted at supercritical temperatures ranging from 375 to 395 °C (tau = 0.27--0.44 s). The operating pressure for the reactions at both subcritical and supercritical conditions was 5000 psig. The results show that the rate-limiting step in

  20. Ultrasonic levitation for the examination of gas/solid reactions

    International Nuclear Information System (INIS)

    Kavouras, A.; Krammer, G.

    2003-01-01

    An experimental setup based on acoustic levitation for the examination of gas/solid reactions is presented. In this setup single particles in the diameter range 1 mm-30 μm can be held against gravity for any wanted time in a defined gas atmosphere at elevated temperatures. The change of particle size, shape, and position can be measured and recorded using an optical device, consisting of a camera and a long range microscope. Basic experiments with inert particles of different shape and solid density have shown that the axial position of a reacting particle can be employed to derive its weight change. A method to evaluate this change of the recorded position for the according weight change is proposed. Exemplary results in the context of dry flue gas cleaning using Ca(OH) 2 powder are presented. Single Ca(OH) 2 particles are exposed to a well defined gas atmosphere and after some time these particles are retrieved from the ultrasonic field for further analyses. Only an in situ measurement of the particle weight change (i.e., without removing the particle from the well defined reactive atmosphere) brings information regarding the uptake of water by the sorbent, which accompanies SO 2 and HCl absorption

  1. Unsteady aspects of sodium-water reaction. Water clearing of sodium containing equipments

    International Nuclear Information System (INIS)

    Carnevali, Sofia

    2012-01-01

    Sodium fast Reactor (FSR) is one of the most promising nuclear reactor concepts in the frame of Generation IV Systems to be commercialised in the next decades. One important safety issue about this technology is the highly exothermal chemical reaction of sodium when brought in contact with liquid water. This situation is likely, in particular during decommissioning, when sodium needs to be firstly converted ('destroyed') into non-reactive species. This is achieved by water washing: the major products are then gaseous hydrogen and corrosive soda. Today, such operations are performed in confined chambers to mitigate the consequences of any possible abnormal conditions. It has for long been believed that the main safety problem was the combustion of hydrogen in the surrounding air despite some pioneering works suggested that even without air the reaction could be explosive. It is extremely important to clarify the phenomenology of sodium-water interactions since available knowledge does not allow a robust extrapolation of existing data/model to full scale plants. The primary objective of this work is to identify and assess the details of the phenomenology, especially at the sodium/water interface, to isolate the leading mechanisms and to propose a robust and innovative modelling approach. A large body of yet unreleased experimental data extracted from the files of the French Commissariat a l'Energie Atomique (CEA) was collated and analysed on the basis of 'explosion' physics. Some additional experiments were also performed to fill some gaps, especially about the kinetics of the reaction. The results strongly suggest that the fast expansion of gas producing a blast wave in certain conditions is a kind of vapour explosion. It also appears that any potential hydrogen-air explosion should be strongly mitigated by the large quantity of water vapour emanating also from the reaction zone. The limitations of existing modelling approaches are clearly

  2. Shale gas: the water myth

    Energy Technology Data Exchange (ETDEWEB)

    O' Shea, Kerry [Dillon Consulting Limited (Canada)

    2010-07-01

    In recent years, due to the depletion of traditional fossil fuel resources and the rising price of energy, production from unconventional gas activities has increased. Large shale gas plays are available in Quebec but environmental concerns, mainly in terms of water resources, have been raised. The aim of this paper is to provide information on the impact of shale gas exploitation on water resources. It is shown herein that shale gas water use is not significant, the water use of 250 wells represents only 0.3% of the Quebec pulp and paper industry's water use, or 0.0004% of the flow of the St Lawrence. It is also shown that the environmental risk associated with fracking and drilling activities is low. This paper demonstrated that as long as industry practices conform to a well-designed regulatory framework, shale gas development in Quebec will have a low impact on water resources and the environment.

  3. Minimization of water consumption under uncertainty for PC process

    Energy Technology Data Exchange (ETDEWEB)

    Salazar, J.; Diwekar, U.; Zitney, S.

    2009-01-01

    Integrated gasification combined cycle (IGCC) technology is becoming increasingly important for the development of advanced power generation systems. As an emerging technology different process configurations have been heuristically proposed for IGCC processes. One of these schemes combines water-gas shift reaction and chemical-looping combustion for the CO2 removal prior the fuel gas is fed to the gas turbine reducing its size (improving economic performance) and producing sequestration-ready CO2 (improving its cleanness potential). However, these schemes have not been energetically integrated and process synthesis techniques can be used to obtain optimal flowsheets and designs. This work studies the heat exchange network synthesis (HENS) for the water-gas shift reaction train employing a set of alternative designs provided by Aspen energy analyzer (AEA) and combined in a process superstructure that was simulated in Aspen Plus (AP). For the alternative designs, large differences in the performance parameters (for instance, the utility requirements) predictions from AEA and AP were observed, suggesting the necessity of solving the HENS problem within the AP simulation environment and avoiding the AEA simplifications. A CAPE-OPEN compliant capability which makes use of a MINLP algorithm for sequential modular simulators was employed to obtain a heat exchange network that provided a cost of energy that was 27% lower than the base case.

  4. Partial Oxidation of n-Pentane over Vanadium Phosphorus Oxide ...

    African Journals Online (AJOL)

    NICOLAAS

    the water gas shift reaction with gold and ruthenium as the ... oven set at 100 °C, followed by calcination under the flow of air at. 500 °C. In the preparation of ..... for gold and ruthenium catalysts: behaviour in the water gas shift reaction, Appl.

  5. Suitability of pipeline material for buried gas and water piping

    Energy Technology Data Exchange (ETDEWEB)

    Funk, R

    1976-01-01

    Following a brief review of the development of the individual pipe materials and their use in the field of gas and water supply, the various stressing possibilities are dealt with. The corrosion influences from inside and outside, the material specifically for internal and external insulation, as well as the stressing due to sediments, are particularly brought out in this connection. A few remarks on the pressure pipes made of ductile cast iron, steel, reinforced concrete, asbestos cement and plastics are followed by comparisons with representations on material parameters to be proved, safety factors, tensile and pressure resistance, breaking tension and stress-strain diagram, wall thicknesses, friction losses, reactions depending on the E. modulus and distribution of the single pipe materials in the gas and water supply.

  6. Water into gas

    International Nuclear Information System (INIS)

    Woodord, Julian.

    1997-01-01

    This article examines the move by water utilities into the gas market and potentially into the electricity supply market. Operation by Dee Valley Holdings, York Waterworks, York Gas, and North Wales Gas are reported, and investment, use of mail campaigns and telemarketing to secure customers, and the opportunities offered by diversification are considered. (UK)

  7. Uranium oxidation: Characterization of oxides formed by reaction with water by infrared and sorption analyses

    Science.gov (United States)

    Fuller, E. L.; Smyrl, N. R.; Condon, J. B.; Eager, M. H.

    1984-04-01

    Three different uranium oxide samples have been characterized with respect to the different preparation techniques. The results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. Inert gas sorption analyses and diffuse reflectance infrared studies combined with electron microscopy prove valuable in defining the chemistry and morphology of the oxidic products and hydrated intermediates.

  8. Experimental determination of reaction rates of water. Hydrogen exchange of tritium with hydrophobic catalysts

    International Nuclear Information System (INIS)

    Bixel, J.C.; Hartzell, B.W.; Park, W.K.

    1976-01-01

    This study was undertaken to obtain data needed for further development of a process for the enrichment and removal of tritium from the water associated with light-water reactors, fuel-reprocessing plants, and tritium-handling laboratories. The approach is based on the use of antiwetting, hydrophobic catalysts which permit the chemical exchange reactions between liquid water and gaseous hydrogen in direct contact, thus eliminating problems of catalyst deactivation and the complexity of reactor design normally associated with current catalytic-detritiation techniques involving gas-phase catalysis. An apparatus and procedure were developed for measuring reaction rates of water-hydrogen chemical exchange with hydrophobic catalysts. Preliminary economic evaluations of the process were made as it might apply to the AGNS fuel reprocessing plant

  9. Small leak detection by measuring surface oscillation during sodium-water reaction in steam generator

    International Nuclear Information System (INIS)

    Nei, Hiromichi; Hori, Masao

    1977-01-01

    Small leak sodium-water reaction tests were conducted to develop various kinds of leak detectors for the sodium-heated steam generator in FBR. The super-heated steam was injected into sodium in a reaction vessel having a sodium free surface, simulating the steam generator. The level gauge in the reaction vessel generated the most reliable signal among detectors, as long as the leak rates were relatively high. The level gauge signal was estimated to be the sodium surface oscillation caused by hydrogen bubbles produced in sodium-water reaction. Experimental correlation was derived, predicting the amplitude as a function of leak rate, hydrogen dissolution ratio, bubble rise velocity and other parameters concerned, assuming that the surface oscillation is in proportion to the gas hold-up. The noise amplitude under normal operation without water leak was increased with sodium flow rate and found to be well correlated with Froud number. These two correlations predict that a water leak in a ''MONJU'' class (300 MWe) steam generator could possibly be detected by level gauges at a leak rate above 2 g/sec. (auth.)

  10. The effectiveness of healthy meals at work on reaction time, mood and dietary intake: a randomised cross-over study in daytime and shift workers at an university hospital

    DEFF Research Database (Denmark)

    Leedo, Eva; Beck, Anne Marie; Astrup, Arne

    2017-01-01

    Our dietary habits affect both cognitive performance and mood. The aim of the study was to examine the effect of increased availability of healthy meals and water at work on healthcare staff. The study used an 8-week randomised cross-over design. A total of sixty physicians, nurses and nursing...... assistants, including sixteen working on shifts, were recruited. The participants received a self-selected keyhole-labelled (Nordic nutrition label) lunch, snack and bottled water during each shift throughout the intervention period. Reaction time (Go/No-Go test), mood-related scores (POMS) and dietary....... The intervention had no effect on reaction time or any of the mood-related scores in the group as a whole. In shift-working participants, the intervention period resulted in a 31·1 % lower Fatigue-Inertia Score (P=0·003), a 15·3 % higher Vigour-Activity Score (P=0·041) and a 42·7 % lower Total Mood Disturbance...

  11. Gas in your water well

    International Nuclear Information System (INIS)

    2011-03-01

    In Alberta, the presence of carbon dioxide, methane or hydrogen sulphide in water wells is common. The aim of this paper is to provide information to private owners of water wells. It is stated in this document that spurting taps or a gurgling noise indicate that there is gas in your water well; you can determine which gas it is by collecting a sample and having it analyzed. In order to address the risks associated with the presence of gas in the water well, the well pit or well pump should be properly vented to avoid any oxygen deficiency in the atmosphere. It is also possible to get rid of the gas by lowering the pump intake. It is also mentioned that the development of coalbed methane in Alberta should not contaminate private wells since regulations aimed at avoiding this have been implemented. This paper provided useful information to help private owners manage the presence of gas in their water wells.

  12. Gas and water permeability of concrete for reactor buildings small specimens

    International Nuclear Information System (INIS)

    Mills, R.H.

    1986-03-01

    The effect on permeability of artifical aging by drying shrinkage and by freeze-thaw was determined by observing mass transfer of gas and water under a pressure gradient. It was found that damage due to freeze-thaw was negligible but that cracking around aggregate caused by drying shrinkage resulted in significantly increased permeability to both gas and water. The absence of freeze-thaw damage was attributed to self-dessication. Since the concrete was not exposed to an external source of water, the chemical reaction was sustained by consumption of mixing water. The resulting air voids were, apparently, sufficient to absorb expansive pressures due to ice formation. The response to lateral prestress was different for cracked and uncracked concrete. Although, in all cases, increased prestress resulted in reduced leakage, the effect was stronger in cracked concrete. Mean pore diameter as determined by gas diffusion was not, however, substantially affected because the leakage in cracked concrete remained very low. Reinforcing steel did not have a great influence on permeability of small specimens. Gas transmission through concrete was strongly influenced by moisture content. Free moisture constituted a barrier to gas flow, acting as a virtual solid. This is important since aging of concrete results in reduced free moisture. Ultrasonic pulse velocity appeared to vary with moisture content and porosity of concrete in the same way as gas permeability and gave promise of being effective for in-situ monitoring of concrete in reactor buildings

  13. Demand grows in N. America as gas supply sources shift

    International Nuclear Information System (INIS)

    Carson, M.M.

    1996-01-01

    Growing demand for gas as a power-generation fuel is combining with changing patterns of gas transportation to present North American producers and pipelines with a series of new challenges. Results of a recent Enron study show how natural gas supplies available to US markets continue to shift their center of gravity toward Canadian and western sources. These changes--demand growth paced by electricity generation and supply source relocation--plus extraordinary gas basin price differentials this winter, point to (a) the opportunities for and risks of adding pipeline capacity in the US and Canada, on the one hand, and (b) tough decisions that may need to be made by Gulf of Mexico and Midcontinent area producers, on the other, to compete in an environment of changing economics and infrastructure

  14. Experimental studies of water hammer in propellant feed system of reaction control system

    Directory of Open Access Journals (Sweden)

    Avanish Kumar

    2018-03-01

    Full Text Available Water hammer pressure transient produces large dynamic forces which can damage the pipes and other assemblies in the feed line of a reaction control system (RCS. It has led to the failure of pressure transducers monitoring the manifold pressure in the feed line of RCS. Therefore, water hammer studies have been carried out to understand its effect in feed line. Feedline system has been simplified to develop a mathematical model and experiments have been carried out at extensive levels. The mathematical model was developed considering pipe of uniform c/s and moving liquid-gas interface. The experimental studies have been done using water as working medium instead of actual propellant. The studies showed that rate of pressurization have a very critical role on the water hammer amplitude. Sensitivity studies have been also carried out to study the effect of density, friction and initial liquid column length on water hammer amplitude. Keywords: Water hammer, Reaction control system (RCS, Propellant feed system, Experimental study, Testing

  15. Coating of graphite flakes with MgO/carbon nanocomposite via gas state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M., E-mail: Sharif_m@metaleng.iust.ac.i [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Faghihi-Sani, M.A. [Sharif University of Technology, Tehran (Iran, Islamic Republic of); Golestani-Fard, F. [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Saberi, A. [Tabriz University (Iran, Islamic Republic of); Soltani, Ali Khalife [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2010-06-18

    Coating of graphite flakes with MgO/carbon nanocomposite was carried out via gaseous state reaction between mixture of Mg metal, CO gas and graphite flakes at 1000 {sup o}C. XRD and FE-SEM analysis of coating showed that the coating was comprised of MgO nano particles and amorphous carbon distributed smoothly and covered the graphite surface evenly. Thermodynamic calculations were employed to predict the reaction sequences as well as phase stability. The effect of coating on water wettability and oxidation resistance of graphite was studied using contact angle measurement and TG analysis, respectively. It was demonstrated that the reaction between Mg and CO could result in MgO/C nanocomposite deposition. The coating improved water wettability of graphite and also enhanced the oxidation resistance of graphite flakes significantly. Also the graphite coating showed significant phenolic resin-wettabilty owing to high surface area of such hydrophilic nano composite coating. The importance of graphite coating is explained with emphasis on its potential application in graphite containing refractories.

  16. Graphite-moderated and heavy water-moderated spectral shift controlled reactors; Reactores de moderador solido controlados por desplazamiento espectral

    Energy Technology Data Exchange (ETDEWEB)

    Alcala Ruiz, F

    1984-07-01

    It has been studied the physical mechanisms related with the spectral shift control method and their general positive effects on economical and non-proliferant aspects (extension of the fuel cycle length and low proliferation index). This methods has been extended to non-hydrogenous fuel cells of high moderator/fuel ratio: heavy water cells have been con- trolled by graphite rods graphite-moderated and gas-cooled cells have been controlled by berylium rods and graphite-moderated and water-cooled cells have been controlled by a changing mixture of heavy and light water. It has been carried out neutron and thermal analysis on a pre design of these types of fuel cells. We have studied its neutron optimization and their fuel cycles, temperature coefficients and proliferation indices. Finally, we have carried out a comparative analysis of the fuel cycles of conventionally controlled PWRs and graphite-moderated, water-cooled and spectral shift controlled reactors. (Author) 71 refs.

  17. Towards the interaction between calcium carbide and water during gas-chromatographic determination of trace moisture in ultra-high purity ammonia.

    Science.gov (United States)

    Trubyanov, Maxim M; Mochalov, Georgy M; Suvorov, Sergey S; Puzanov, Egor S; Petukhov, Anton N; Vorotyntsev, Ilya V; Vorotyntsev, Vladimir M

    2018-05-16

    The current study focuses on the processes involved during the flow conversion of water into acetylene in a calcium carbide reaction cell for the trace moisture analysis of ammonia by reaction gas chromatography. The factors negatively affecting the reproducibility and the accuracy of the measurements are suggested and discussed. The intramolecular reaction of the HOCaCCH intermediate was found to be a side reaction producing background acetylene during the contact of wet ammonia gas with calcium carbide. The presence of the HOCaCCH intermediate among the reaction products is confirmed by an FTIR spectral study of calcium carbide powder exposed to wet gas. The side reaction kinetics is evaluated experimentally and its influence on the results of the gas chromatographic measurements is discussed in relation to the determination of the optimal operating parameters for ammonia analysis. The reaction gas chromatography method for the trace moisture measurements in an ammonia matrix was experimentally compared to an FTIR long-path length gas cell technique to evaluate the accuracy limitations and the resource intensity. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Kinetics of the Coupled Gas-Iron Reactions Involving Silicon and ...

    African Journals Online (AJOL)

    The kinetic study of coupled gas-iron reactions at 15600 has been carried out for the system involving liquid iron containing carbon and silicon and a gas phase consisting carbon monoxide, silicon monoxide and carbon dioxide. The coupled reactions are: (1) 200(g) = CO2 + C. (2) SiO (g) + CO (g) = Si ¸ CO (g). (3) SiO (g) + ...

  19. Solvent effects and potential of mean force study of the SN2 reaction of CH3+CN‑ in water

    Science.gov (United States)

    Li, Chen; Liu, Peng; Li, Yongfang; Wang, Dunyou

    2018-03-01

    We used a combined quantum mechanics and molecular mechanics (QM/MM) method to investigate the solvent effects and potential of mean force of the CH3F+CN‑ reaction in water. Comparing to gas phase, the water solution substantially affects the structures of the stationary points along the reaction path. We quantitatively obtained the solvent effects’ contributions to the reaction: 1.7 kcal/mol to the activation barrier and ‑26.0 kcal/mol to the reaction free energy. The potential mean of force calculated with the density functional theory/MM theory has a barrier height at 19.7 kcal/mol, consistent with the experimental result at 23.0 kcal/mol; the calculated reaction free energy at ‑43.5 kcal/mol is also consistent with the one estimated based on the gas-phase data at ‑39.7 kcal/mol. Project supported by the National Natural Science Foundation of China (Grant No. 11774206) and Taishan Scholarship Fund from Shandong Province, China.

  20. Gas transmission : a paradigm shift

    International Nuclear Information System (INIS)

    Cornelson, D.W.

    1997-01-01

    The evolution of energy markets in North America was discussed. The investment opportunities that are possible in a deregulated energy market, be it in production or in the generation of energy commodities, in the development of midstream infrastructure, or in the provision of energy services, were outlined. Deregulation of crude oil, natural gas and electricity has resulted in significant changes in the structure of energy markets and the way in which customers are served. One of the advantages of competition regarding power generation is that it has turned energy into a commodity which has resulted in greater customer choice and efficiency. As one example of midstream infrastructure development, the Alliance Pipeline project was described. This project was conceived as a means to enhance the value of western Canadian natural gas. The 1,900 mile pipeline will run from British Columbia, through Alberta into Chicago where it will interconnect with the North American gas transmission grid. The pipeline is an efficient means of transporting energy from Western Canada to North American markets, and Alliance, as a lowest cost transporter, will continue to put pressure on the traditional infrastructure to become even more competitive at the margin. As such, Alliance represents a paradigm shift in energy transportation, and serves as an excellent example of the type of investment opportunity that a deregulated market can provide. It was suggested that innovation and competition in a deregulated North American energy market will continue to increase. As electricity is deregulated, the energy market will respond more quickly to changes in supply and demand than it did in the past, in an effort to satisfy the needs of investors and customers. This will provide increased opportunities for restructuring and further competition

  1. Measurement of water absorption capacity in wheat flour by a headspace gas chromatographic technique.

    Science.gov (United States)

    Xie, Wei-Qi; Yu, Kong-Xian; Gong, Yi-Xian

    2018-04-17

    The purpose of this work is to introduce a new method for quantitatively analyzing water absorption capacity in wheat flour by a headspace gas chromatographic technique. This headspace gas chromatographic technique was based on measuring the water vapor released from a series of wheat flour samples with different contents of water addition. According to the different trends between the vapor and wheat flour phase before and after the water absorption capacity in wheat flour, a turning point (corresponding to water absorption capacity in wheat flour) can be obtained by fitting the data of the water gas chromatography peak area from different wheat flour samples. The data showed that the phase equilibrium in the vial can be achieved in 25 min at desired temperature (35°C). The relative standard deviation of the reaction headspace gas chromatographic technique in water absorption capacity determination was within 3.48%, the relative differences has been determined by comparing the water absorption capacity obtained from this new analytical technique with the data from the reference technique (i.e., the filtration method), which are less than 8.92%. The new headspace gas chromatographic method is automated, accurate and be a reliable tool for quantifying water absorption capacity in wheat flour in both laboratory research and mill applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Visual observation of gas hydrates nucleation and growth at a water - organic liquid interface

    Science.gov (United States)

    Stoporev, Andrey S.; Semenov, Anton P.; Medvedev, Vladimir I.; Sizikov, Artem A.; Gushchin, Pavel A.; Vinokurov, Vladimir A.; Manakov, Andrey Yu.

    2018-03-01

    Visual observation of nucleation sites of methane and methane-ethane-propane hydrates and their further growth in water - organic liquid - gas systems with/without surfactants was carried out. Sapphire Rocking Cell RCS6 with transparent sapphire cells was used. The experiments were conducted at the supercooling ΔTsub = 20.2 °C. Decane, toluene and crude oils were used as organics. Gas hydrate nucleation occurred on water - metal - gas and water - sapphire - organic liquid three-phase contact lines. At the initial stage of growth hydrate crystals rapidly covered the water - gas or water - organics interfaces (depending on the nucleation site). Further hydrate phase accrete on cell walls (sapphire surface) and into the organics volume. At this stage, growth was accompanied by water «drawing out» from under initial hydrate film formed at water - organic interface. Apparently, it takes place due to water capillary inflow in the reaction zone. It was shown that the hydrate crystal morphology depends on the organic phase composition. In the case of water-in-decane emulsion relay hydrate crystallization was observed in the whole sample, originating most likely due to the hydrate crystal intergrowth through decane. Contacts of such crystals with adjacent water droplets result in rapid hydrate crystallization on this droplet.

  3. Mars Atmospheric Capture and Gas Separation

    Science.gov (United States)

    Muscatello, Anthony; Santiago-Maldonado, Edgardo; Gibson, Tracy; Devor, Robert; Captain, James

    2011-01-01

    The Mars atmospheric capture and gas separation project is selecting, developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Trace gases will be required to be separated from Martian atmospheric gases to provide pure C02 to processing elements. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and should be captured as welL To achieve these goals, highly efficient gas separation processes will be required. These gas separation techniques are also required across various areas within the ISRU project to support various consumable production processes. The development of innovative gas separation techniques will evaluate the current state-of-the-art for the gas separation required, with the objective to demonstrate and develop light-weight, low-power methods for gas separation. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from un-reacted carbon oxides (C02- CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, (3) carbon oxides from oxygen from a trash/waste processing reaction, and (4) helium from hydrogen or oxygen from a propellant scavenging process. Potential technologies for the separations include freezers, selective membranes, selective solvents, polymeric sorbents, zeolites, and new technologies. This paper and presentation will summarize the results of an extensive literature review and laboratory evaluations of candidate technologies for the capture and separation of C02 and other relevant gases.

  4. Carbon-14 immobilization via the CO2-Ba(OH)2 hydrate gas-solid reaction

    International Nuclear Information System (INIS)

    Haag, G.L.

    1980-01-01

    Although no restrictions have been placed on the release of carbon-14, it has been identified as a potential health hazard due to the ease in which it may be assimilated into the biosphere. The intent of the Carbon-14 Immobilization Program, funded through the Airborne Waste Program Management Office, is to develop and demonstrate a novel process for restricting off-gas releases of carbon-14 from various nuclear facilities. The process utilizes the CO 2 -Ba(OH) 2 hydrate gas-solid reaction to directly remove and immobilize carbon-14. The reaction product, BaCO 3 , possesses both the thermal and chemical stability desired for long-term waste disposal. The process is capable of providing decontamination factors in excess of 1000 and reactant utilization of greater than 99% in the treatment of high volumetric, airlike (330 ppM CO 2 ) gas streams. For the treatment of an air-based off-gas stream, the use of packed beds of Ba(OH) 2 .8H 2 O flakes to remove CO 2 has been demonstrated. However, the operating conditions must be maintained between certain upper and lower limits with respect to the partial pressure of water. If the water vapor pressure in the gas is less than the dissociation vapor pressure of Ba(OH) 2 .8H 2 O, the bed will deactivate. If the vapor pressure is considerably greater, pressure drop problems will increase with increasing humidity as the particles curl and degrade. Results have indicated that when operated in the proper regime, the bulk of the increase in pressure drop results from the conversion of Ba(OH) 2 .8H 2 O to BaCO 3 and not from the hydration of the commercial Ba(OH) 2 .8H 2 O (i.e. Ba(OH) 2 .7.50H 2 O) to Ba(OH) 2 .8H 2 O

  5. A hetero retro Diels-Alder reaction in aqueous solution : A dramatic water-induced increase of the equilibrium constant and inhibition of cycloreversion

    NARCIS (Netherlands)

    Wijnen, J.W; Engberts, J.B.F.N.

    The adduct of the Diels-Alder reaction of nitrosobenzene with cyclopentadiene is not stable in solution. The equilibrium constant for the reaction depends strongly on the medium and water induces a spectacular shift to the adduct. Comparison with the bimolecular addition of nitrosobenzene to

  6. A flow reactor setup for photochemistry of biphasic gas/liquid reactions

    Directory of Open Access Journals (Sweden)

    Josef Schachtner

    2016-08-01

    Full Text Available A home-built microreactor system for light-mediated biphasic gas/liquid reactions was assembled from simple commercial components. This paper describes in full detail the nature and function of the required building elements, the assembly of parts, and the tuning and interdependencies of the most important reactor and reaction parameters. Unlike many commercial thin-film and microchannel reactors, the described set-up operates residence times of up to 30 min which cover the typical rates of many organic reactions. The tubular microreactor was successfully applied to the photooxygenation of hydrocarbons (Schenck ene reaction. Major emphasis was laid on the realization of a constant and highly reproducible gas/liquid slug flow and the effective illumination by an appropriate light source. The optimized set of conditions enabled the shortening of reaction times by more than 99% with equal chemoselectivities. The modular home-made flow reactor can serve as a prototype model for the continuous operation of various other reactions at light/liquid/gas interfaces in student, research, and industrial laboratories.

  7. Frequency shift of the Bragg and Non-Bragg backscattering from periodic water wave

    Science.gov (United States)

    Wen, Biyang; Li, Ke

    2016-08-01

    Doppler effect is used to measure the relative speed of a moving target with respect to the radar, and is also used to interpret the frequency shift of the backscattering from the ocean wave according to the water-wave phase velocity. The widely known relationship between the Doppler shift and the water-wave phase velocity was deduced from the scattering measurements data collected from actual sea surface, and has not been verified under man-made conditions. Here we show that this ob- served frequency shift of the scattering data from the Bragg and Non-Bragg water wave is not the Doppler shift corresponding to the water-wave phase velocity as commonly believed, but is the water-wave frequency and its integral multiple frequency. The power spectrum of the backscatter from the periodic water wave consists of serials discrete peaks, which is equally spaced by water wave frequency. Only when the water-wave length is the integer multiples of the Bragg wave, and the radar range resolution is infinite, does the frequency shift of the backscattering mathematically equal the Doppler shift according to the water-wave phase velocity.

  8. Temperature dependence on sodium-water chemical reaction

    International Nuclear Information System (INIS)

    Tamura, Kenta; Deguchi, Yoshihiro; Suzuki, Koichi; Takata, Takashi; Yamaguchi, Akira; Kikuchi, Shin; Ohshima, Hiroyuki

    2012-01-01

    In a sodium-cooled fast reactor (SFR), liquid sodium is used as a heat transfer fluid because of its excellent heat transport capability. On the other hand, it has strong chemical reactivity with water vapor. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow by a breach of heat transfer tubes. This process ends up damages on the heat transport equipment in the SFR. Therefore, the study on sodium-water chemical reactions is of paramount importance for security reasons. This study aims to clarify the sodium-water reaction mechanisms using laser diagnostics. A quasi one-dimensional flame model is also applied to a sodium-water counter-flow reaction field. Temperature, H 2 , H 2 O, OH, Na and Particulate matter were measured using laser induced fluorescence and CARS in the counter-flow reaction field. The temperature of the reaction field was also modified to reduce the condensation of Na in the reaction zone. (author)

  9. Utilizing the dynamic stark shift as a probe for dielectric relaxation in photosynthetic reaction centers during charge separation.

    Science.gov (United States)

    Guo, Zhi; Lin, Su; Woodbury, Neal W

    2013-09-26

    In photosynthetic reaction centers, the electric field generated by light-induced charge separation produces electrochromic shifts in the transitions of reaction center pigments. The extent of this Stark shift indirectly reflects the effective field strength at a particular cofactor in the complex. The dynamics of the effective field strength near the two monomeric bacteriochlorophylls (BA and BB) in purple photosynthetic bacterial reaction centers has been explored near physiological temperature by monitoring the time-dependent Stark shift during charge separation (dynamic Stark shift). This dynamic Stark shift was determined through analysis of femtosecond time-resolved absorbance change spectra recorded in wild type reaction centers and in four mutants at position M210. In both wild type and the mutants, the kinetics of the dynamic Stark shift differ from those of electron transfer, though not in the same way. In wild type, the initial electron transfer and the increase in the effective field strength near the active-side monomer bacteriochlorophyll (BA) occur in synchrony, but the two signals diverge on the time scale of electron transfer to the quinone. In contrast, when tyrosine is replaced by aspartic acid at M210, the kinetics of the BA Stark shift and the initial electron transfer differ, but transfer to the quinone coincides with the decay of the Stark shift. This is interpreted in terms of differences in the dynamics of the local dielectric environment between the mutants and the wild type. In wild type, comparison of the Stark shifts associated with BA and BB on the two quasi-symmetric halves of the reaction center structure confirm that the effective dielectric constants near these cofactors are quite different when the reaction center is in the state P(+)QA(-), as previously determined by Steffen et al. at 1.5 K (Steffen, M. A.; et al. Science 1994, 264, 810-816). However, it is not possible to determine from static, low-temperature measurments if the

  10. Simulasi Pengaruh Kandungan CO2 dalam Gas Umpan terhadap Reforming dan Shift Converter Sistem Pabrik Amoniak

    Directory of Open Access Journals (Sweden)

    Jefry Yusuf

    2015-12-01

    Full Text Available Perubahan produksi dan pangsa pasar gas alam domestik maupun global mempengaruhi suplai terhadap pabrik pupuk-amoniak baik dari sisi jumlah, komposisi maupun harga. Kondisi ini memungkinkan pabrik amoniak menerima jenis gas alam berat kaya dengan CO2 (raw gas maupun gas alam  ringan minim CO2 (treated gas. Pada penelitian ini telah dilakukan analisa pengaruh perubahan  komposisi gas alam terutama kandungan CO2 dengan variasi 0, 5, 10, 15, 20, 25, 30, 35, 40, 45 dan 50% vol terhadap operasional reforming dan shift converter sistem pabrik amoniak-2 PT. PI Mexisting dengan metodelogi simulasi mengggunakan Aspen HYSYS V8.0. Untuk memproduksi amoniak dengan jumlah yang sama, hasil studi menunjukkan penambahan CO2 dalam gas umpan akan meningkatkan pressure drop sistem, laju pembentukan komponen hidrogen turun sementara konsumsi energi bertambah di reforming, beban katalis shift converter dan beban feed gas compressor meningkat. Kandungan CO2 sebesar 7% vol masih mungkin diaplikasikan, mengingat ada batasan beban peralatan.

  11. SWAAM-LT: The long-term, sodium/water reaction analysis method computer code

    International Nuclear Information System (INIS)

    Shin, Y.W.; Chung, H.H.; Wiedermann, A.H.; Tanabe, H.

    1993-01-01

    The SWAAM-LT Code, developed for analysis of long-term effects of sodium/water reactions, is discussed. The theoretical formulation of the code is described, including the introduction of system matrices for ease of computer programming as a general system code. Also, some typical results of the code predictions for available large scale tests are presented. Test data for the steam generator design with the cover-gas feature and without the cover-gas feature are available and analyzed. The capabilities and limitations of the code are then discussed in light of the comparison between the code prediction and the test data

  12. Exergy analysis of a hydrogen fired combined cycle with natural gas reforming and membrane assisted shift reactors for CO2 capture

    International Nuclear Information System (INIS)

    Atsonios, K.; Panopoulos, K.D.; Doukelis, A.; Koumanakos, A.; Kakaras, Em.

    2012-01-01

    Highlights: ► Exergy analysis of NGCC with CCS. ► WGS-MR: exergetically efficient technology for CCS, less than 2% total exergy losses. ► 10% of total exergy dissipation in the ATR. ► Optimization of ATR operation and CO 2 stream treatment. - Abstract: Hydrogen production from fossil fuels together with carbon capture has been suggested as a means of providing a carbon free power. The paper presents a comparative exergetic analysis performed on the hydrogen production from natural gas with several combinations of reactor systems: (a) oxy or air fired autothermal reforming with subsequent water gas shift reactor and (b) membrane reactor assisted with shift catalysts. The influence of reactor temperature and pressure as well as operating parameter steam-to-carbon ratio, is also studied exergetically. The results indicate optimal power plant configurations with CO 2 capture, or hydrogen delivery for industrial applications.

  13. Development and test of a new catalytic converter for natural gas ...

    Indian Academy of Sciences (India)

    catalytic converter and a new natural gas engine such as compressed natural gas. (CNG) direct ..... bility to store oxygen from random gas flow within the substrate in comparison to flow through ..... and behaviour in the water–gas shift reaction.

  14. Facile nanofibrillation of chitin derivatives by gas bubbling and ultrasonic treatments in water.

    Science.gov (United States)

    Tanaka, Kohei; Yamamoto, Kazuya; Kadokawa, Jun-ichi

    2014-10-29

    In this paper, we report that nanofiber network structures were constructed from chitin derivatives by gas bubbling and ultrasonic treatments in water. When chitin was first subjected to N2 gas bubbling with ultrasonication in water, the SEM images of the product showed nanofiber network morphology. However, nanofiber network was not re-constructed by the same N2 gas bubbling and ultrasonic treatments after agglomeration. We then have paid attention to an amidine group to provide the agglomeration-nanofibrillation behavior of chitin derivatives. An amidinated chitin was synthesized by the reaction of the amino groups in a partially deacetylated chitin with N,N-dimethylacetamide dimethyl acetal, which was subjected to CO2 gas bubbling and ultrasonic treatments in water to convert into an amidinium chitin by protonation. The SEM images of the product clearly showed nanofiber network morphology. We further examined re-nanofibrillation of the agglomerated material, which was obtained by mixing the nanofibrillated amidinium chitin with water, followed by drying under reduced pressure. Consequently, the material was re-nanofibrillated by N2 gas bubbling with ultrasonication in water owing to electrostatic repulsion between the amidinium groups. Furthermore, deprotonation of the amidinium chitin and re-protonation of the resulting amidinated chitin were conducted by alkaline treatment and CO2 gas bubbling-ultrasonic treatments, respectively. The material showed the agglomeration-nanofibrillation behavior during the processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Tuning Catalytic Performance through a Single or Sequential Post-Synthesis Reaction(s) in a Gas Phase

    Energy Technology Data Exchange (ETDEWEB)

    Shan, Junjun [Department; Department; Zhang, Shiran [Department; Department; Choksi, Tej [Department; Nguyen, Luan [Department; Department; Bonifacio, Cecile S. [Department; Li, Yuanyuan [Department; Zhu, Wei [Department; Department; College; Tang, Yu [Department; Department; Zhang, Yawen [College; Yang, Judith C. [Department; Greeley, Jeffrey [Department; Frenkel, Anatoly I. [Department; Tao, Franklin [Department; Department

    2016-12-05

    Catalytic performance of a bimetallic catalyst is determined by geometric structure and electronic state of the surface or even the near-surface region of the catalyst. Here we report that single and sequential postsynthesis reactions of an as-synthesized bimetallic nanoparticle catalyst in one or more gas phases can tailor surface chemistry and structure of the catalyst in a gas phase, by which catalytic performance of this bimetallic catalyst can be tuned. Pt–Cu regular nanocube (Pt–Cu RNC) and concave nanocube (Pt–Cu CNC) are chosen as models of bimetallic catalysts. Surface chemistry and catalyst structure under different reaction conditions and during catalysis were explored in gas phase of one or two reactants with ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The newly formed surface structures of Pt–Cu RNC and Pt–Cu CNC catalysts strongly depend on the reactive gas(es) used in the postsynthesis reaction(s). A reaction of Pt–Cu RNC-as synthesized with H2 at 200 °C generates a near-surface alloy consisting of a Pt skin layer, a Cu-rich subsurface, and a Pt-rich deep layer. This near-surface alloy of Pt–Cu RNC-as synthesized-H2 exhibits a much higher catalytic activity in CO oxidation in terms of a low activation barrier of 39 ± 4 kJ/mol in contrast to 128 ± 7 kJ/mol of Pt–Cu RNC-as synthesized. Here the significant decrease of activation barrier demonstrates a method to tune catalytic performances of as-synthesized bimetallic catalysts. A further reaction of Pt–Cu RNC-as synthesized-H2 with CO forms a Pt–Cu alloy surface, which exhibits quite different catalytic performance in CO oxidation. It suggests the capability of generating a different surface by using another gas. The capability of tuning surface chemistry and structure of bimetallic catalysts was also demonstrated in restructuring of Pt–Cu CNC-as synthesized.

  16. C-terminal peptide extension via gas-phase ion/ion reactions

    Science.gov (United States)

    Peng, Zhou; McLuckey, Scott A.

    2015-01-01

    The formation of peptide bonds is of great importance from both a biological standpoint and in routine organic synthesis. Recent work from our group demonstrated the synthesis of peptides in the gas-phase via ion/ion reactions with sulfo-NHS reagents, which resulted in conjugation of individual amino acids or small peptides to the N-terminus of an existing ‘anchor’ peptide. Here, we demonstrate a complementary approach resulting in the C-terminal extension of peptides. Individual amino acids or short peptides can be prepared as reagents by incorporating gas phase-labile protecting groups to the reactive C-terminus and then converting the N-terminal amino groups to the active ketenimine reagent. Gas-phase ion/ion reactions between the anionic reagents and doubly protonated “anchor” peptide cations results in extension of the “anchor” peptide with new amide bond formation at the C-terminus. We have demonstrated that ion/ion reactions can be used as a fast, controlled, and efficient means for C-terminal peptide extension in the gas phase. PMID:26640400

  17. The Synergy Effect of Ni-M (M = Mo, Fe, Co, Mn or Cr Bicomponent Catalysts on Partial Methanation Coupling with Water Gas Shift under Low H2/CO Conditions

    Directory of Open Access Journals (Sweden)

    Xinxin Dong

    2017-02-01

    Full Text Available Ni-M (M = Mo, Fe, Co, Mn or Cr bicomponent catalysts were prepared through the co-impregnation method for upgrading low H2/CO ratio biomass gas into urban gas through partial methanation coupling with water gas shift (WGS. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction (XRD, H2 temperature programmed reduction (H2-TPR, H2 temperature programmed desorption (H2-TPD, scanning electron microscopy (SEM and thermogravimetry (TG. The catalytic performances demonstrated that Mn and Cr were superior to the other three elements due to the increased fraction of reducible NiO particles, promoted dispersion of Ni nanoparticles and enhanced H2 chemisorption ability. The comparative study on Mn and Cr showed that Mn was more suitable due to its smaller carbon deposition rate and wider adaptability to various H2/CO and H2O/CO conditions, indicating its better synergy effect with Ni. A nearly 100 h, the lifetime test and start/stop cycle test further implied that 15Ni-3Mn was stable for industrial application.

  18. Trends in low-temperature water–gas shift reactivity on transition metals

    DEFF Research Database (Denmark)

    Schumacher, Nana Maria Pii; Boisen, Astrid; Dahl, Søren

    2005-01-01

    Low-temperature water–gas shift reactivity trends on transition metals were investigated with the use of a microkinetic model based on a redox mechanism. It is established that the adsorption energies for carbon monoxide and oxygen can describe to a large extent changes in the remaining activation...

  19. Laboratory investigations of the alpha-pinene/ozone gas-phase reaction

    International Nuclear Information System (INIS)

    Benner, C.L.

    1985-01-01

    In order to provide more insight into terpene photooxidation or ozonolysis reaction mechanisms, a radiotracer technique was developed. This technique was applied to an investigation of the 14 C-alpha-pinene/ozone reaction. In the first phase of the research, the carbon distribution at the conclusion of the ozonolysis reaction was determined by separating carbon-14-labelled gaseous products from labelled aerosols, and counting each phase by liquid scintillation methods. The resulting carbon balance was 38% to 60% filtered aerosols, 6% to 20% gas phase compounds, and 11% to 29% products absorbed on the reaction chamber walls. Recoveries of the alpha-pinene carbon-14 ranging from 79% to 97% were achieved using this method. The alpha-pinene concentrations in these experiments were close to ambient (1 part per billion), yet the carbon balance was similar to that observed at much higher concentrations (>1 part per million). In the second phase of the alpha-pinene study, both gas and aerosol products of the ozonolysis reaction were collected on cartridges impregnated with 2,4-dinitrophenylhydrazine, then analyzed by HPLC. In the final experiments, alpha-pinene aerosol was reacted with a silylating agent to improve the detection of organic acids and alcohols. The gas chromatographic/mass spectrometric analysis of the silylated aerosol products showed evidence of dimer/polymer formation occurring in the ozonolysis reaction

  20. Uranium/water vapor reactions in gaseous atmospheres

    International Nuclear Information System (INIS)

    Jackson, R.L.; Condon, J.B.; Steckel, L.M.

    1977-07-01

    Experiments have been performed to determine the effect of varying humidities, gaseous atmospheres, and temperatures on the uranium/water vapor reaction. A balance, which allowed continuous in-system weighings, was used to determine the rates of the uranium/water vapor reactions at water vapor pressures of 383, 1586, and 2853 Pa and at temperatures of 80, 100, and 150 0 C in atmospheres of hydrogen, argon, or argon/oxygen mixtures. Based on rate data, the reactions were characterized as hydriding or nonhydriding. Hydriding reactions were found to be preferred in moist hydrogen systems at the higher temperatures and the lower humidities. The presence of hydrogen in hydriding systems was found to initially inhibit the reaction, but causes an acceleration of the rate in the final stages. In general, reaction rates of hydriding systems approached the hydriding rates calculated and observed in dry hydrogen. Hydriding and nonhydriding reaction rates showed a positive correlation to temperature and water vapor pressure. Final reaction rates in moist argon/oxygen mixtures of 1.93, 4.57, and 9.08 mole percent oxygen were greater than the rates observed in moist hydrogen or argon. Final reaction rates were negatively correlated to the oxygen concentration

  1. Analysis of reaction products formed in the gas phase reaction of E,E-2,4-hexadienal with atmospheric oxidants: Reaction mechanisms and atmospheric implications

    Science.gov (United States)

    Colmenar, I.; Martin, P.; Cabañas, B.; Salgado, S.; Martinez, E.

    2018-03-01

    An analysis of reaction products for the reaction of E,E-2,4-hexadienal with chlorine atoms (Cl) and OH and NO3 radicals has been carried out at the first time with the aim of obtaining a better understanding of the tropospheric reactivity of α,β-unsaturated carbonyl compounds. Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography-Mass Spectrometry with a Time of Flight detector (GC-TOFMS) were used to carry out the qualitative and/or quantitative analyses. Reaction products in gas and particulate phase were observed from the reactions of E,E-2,4- hexadienal with all oxidants. E/Z-Butenedial and maleic anhydride were the main products identified in gas phase. E-butenedial calculated molar yield ranging from 4 to 10%. A significant amount of multifunctional compounds (chloro and hydroxy carbonyls) was identified. These compounds could be formed in particulate phase explaining the ∼90% of unaccounted carbon in gas phase. The reaction with Cl atoms in the presence of NOx with a long reaction time gave Peroxy Acetyl Nitrate (PAN) as an additional product, which is known for being an important specie in the generation of the photochemical smog. Nitrated compounds were the major organic products from the reaction with the NO3 radical. Based on the identified products, the reaction mechanisms have been proposed. In these mechanisms a double bond addition of the atmospheric oxidant at C4/C5 of E,E-2,4-hexadienal is the first step for tropospheric degradation.

  2. Combined Monte Carlo and quantum mechanics study of the solvatochromism of phenol in water. The origin of the blue shift of the lowest pi-pi* transition.

    Science.gov (United States)

    Barreto, Rafael C; Coutinho, Kaline; Georg, Herbert C; Canuto, Sylvio

    2009-03-07

    A combined and sequential use of Monte Carlo simulations and quantum mechanical calculations is made to analyze the spectral shift of the lowest pi-pi* transition of phenol in water. The solute polarization is included using electrostatic embedded calculations at the MP2/aug-cc-pVDZ level giving a dipole moment of 2.25 D, corresponding to an increase of 76% compared to the calculated gas-phase value. Using statistically uncorrelated configurations sampled from the MC simulation, first-principle size-extensive calculations are performed to obtain the solvatochromic shift. Analysis is then made of the origin of the blue shift. Results both at the optimized geometry and in room-temperature liquid water show that hydrogen bonds of water with phenol promote a red shift when phenol is the proton-donor and a blue shift when phenol is the proton-acceptor. In the case of the optimized clusters the calculated shifts are in very good agreement with results obtained from mass-selected free jet expansion experiments. In the liquid case the contribution of the solute-solvent hydrogen bonds partially cancels and the total shift obtained is dominated by the contribution of the outer solvent water molecules. Our best result, including both inner and outer water molecules, is 570 +/- 35 cm(-1), in very good agreement with the small experimental shift of 460 cm(-1) for the absorption maximum.

  3. Gas chromatographic determination of impurities of inorganic compounds

    International Nuclear Information System (INIS)

    Drugov, Yu.S.

    1985-01-01

    Methods of concentration, separation, detection in gas chromatographic determination of impurities of inorganic compounds including low-boiling gases, reactive gases, organometallic compounds, free metals, anions, etc. are reviewed. Methods of reaction gas chromatography for determining reactive gases, water, anions, metal chelates are considered in detail as well as methods of reaction-sorption concentration and reaction gas extraction. The application of gas chromatograpny ior anaiysis of water and atmosphere contamination, for determination of impurities in highly pure solid substances and gases is described

  4. Development of LEAP-JET code for sodium-water reaction analysis. Validation by sodium-water reaction tests (SWAT-1R)

    International Nuclear Information System (INIS)

    Seino, Hiroshi; Hamada, Hirotsugu

    2004-03-01

    The sodium-water reaction event in an FBR steam generator (SG) has influence on the safety, economical efficiency, etc. of the plant, so that the selection of design base leak (DBL) of the SG is considered as one of the important matters. The clarification of the sodium-water reaction phenomenon and the development of an analysis model are necessary to estimate the sodium-water reaction event with high accuracy and rationality in selecting the DBL. The reaction jet model is pointed out as a part of the necessary improvements to evaluate the overheating tube rupture of large SGs, since the behavior of overheating tube rupture is largely affected by the reaction jet conditions outside the tube. Therefore, LEAP-JET has been developed as an analysis code for the simulation of sodium-water reactions. This document shows the validation of the LEAP-JET code by the Sodium-Water Reaction Test (SWAT-1R). The following results have been obtained: (1) The reaction rate constant, K, is estimated at between 0.001≤K≤0.1 from the LEAP-JET analysis of the SWAT-1R data. (2) The analytical results on the high-temperature region and the behaviors of reaction consumption (Na, H 2 O) and products (H 2 , NaOH, Na 2 O) are considered to be physically reasonable. (3) The LEAP-JET analysis shows the tendency of overestimation in the maximum temperature and temperature distribution of the reaction jet. (4) In the LEAP-JET analysis, the numerical calculation becomes unstably, especially in the mesh containing quite small sodium mass. Therefore, it is necessary to modify the computational algorism to stabilize it and obtain the optimum value of K in sodium-water reactions. (author)

  5. Experimental evaluation of improved dual temperature hydrogen isotopic exchange reaction system

    International Nuclear Information System (INIS)

    Asakura, Yamato; Uchida, Shunsuke

    1984-01-01

    A proposed dual temperature hydrogen isotopic exchange reaction system between water and hydrogen gas is evaluated experimentally. The proposed system is composed of low temperature co-current reactors for reaction between water mists and hydrogen gas and high temperature co-current reactors for reaction between water vapor and hydrogen gas. Thus, operation is possible under atmospheric pressure with high reaction efficiency. Using the pilot test system which is composed of ten low temperature (30 0 C) reaction units and ten high temperature (200 0 C) reaction units, an experimental separation of deuterium from light water is carried out. The enrichment factor under steady state conditions, its dependency on operating time, and the reaction period necessary to obtain the steady state enrichment factor are determined experimentally and compared with calculations. It is shown that separation ability in a multistage reaction system can be estimated by numerical calculation using actual reaction efficiency in a unit reactor. (author)

  6. Reactions of newly formed fission products in the gas phase

    International Nuclear Information System (INIS)

    Strickert, R.G.

    1976-01-01

    A dynamic gas-flow system was constructed which stopped fission products in the gas phase and rapidly separated (in less than 2 sec) volatile compounds from non-volatile ones. The filter assembly designed and used was shown to stop essentially all non-volatile fission products. Between 5 percent and 20 percent of tellurium fission-product isotopes reacted with several hydrocarbon gases to form volatile compounds, which passed through the filter. With carbon monoxide gas, volatile tellurium compound(s) (probably TeCO) were also formed with similar efficiencies. The upper limits for the yields of volatile compounds formed between CO and tin and antimony fission products were shown to be less than 0.3 percent, so tellurium nuclides, not their precursors, reacted with CO. It was found that CO reacted preferentially with independently produced tellurium atoms; the reaction efficiency of beta-produced atoms was only 27 +- 3 percent of that of the independently formed atoms. The selectivity, which was independent of the over-all reaction efficiency, was shown to be due to reaction of independently formed atoms in the gas phase. The gas phase reactions are believed to occur mainly at thermal energies because of the independence of the yield upon argon moderator mole-fraction (up to 80 percent). It was shown in some experiments that about one-half of the TeCO decomposed in passing through a filter and that an appreciable fraction (approximately 20 percent) of the tellurium atoms deposited on the filter reacted agin with CO. Other tellurium atoms on the filter surface (those formed by beta decay and those formed independently but not reacting in the gas phase) also reacted with CO, but probably somewhat less efficiently than atoms formed by TeCO decomposition. No evidence was found for formation of TeCO as a direct result of beta-decay

  7. Development of blow down and sodium-water reaction jet analysis codes-Validation by sodium-water reaction tests (SWAT-1R)

    International Nuclear Information System (INIS)

    Hiroshi Seino; Akikazu Kurihara; Isao Ono; Koji Jitsu

    2005-01-01

    Blow down analysis code (LEAP-BLOW) and sodium-water reaction jet analysis code (LEAP-JET) have been developed in order to improve the evaluation method on sodium-water reaction event in the steam generator (SG) of a sodium cooled fast breeder reactor (FBR). The validation analyses by these two codes were carried out using the data of Sodium-Water Reaction Test (SWAT-1R). The following main results have been obtained through this validation: (1) The calculational results by LEAP-BLOW such as internal pressure and water flow rate show good agreement with the results of the SWAT- 1R test. (2) The LEAP-JET code can qualitatively simulate the behavior of sodium-water reaction. However, it is found that the code has tendency to overestimate the maximum temperature of the reaction jet. (authors)

  8. Effect of sulfur dioxide partial pressure on the reaction of iodine, sulfur dioxide and water

    International Nuclear Information System (INIS)

    Nakajima, Hayato; Imai, Yoshiyuki; Kasahara, Seiji; Kubo, Shinji; Onuki, Kaoru

    2007-01-01

    Effect of sulfur dioxide partial pressure on the reaction of iodine, sulfur dioxide and water, which is a unit reaction in the IS process for thermochemical hydrogen production, was studied experimentally at 323 K under iodine saturation. Quasi-equilibrium state was observed in the presence of sulfur dioxide gas at constant pressure. The composition of the poly-hydriodic acid solution formed was discussed assuming an ideal desulfurization by the reverse reaction of the Bunsen reaction. The value of HI/(HI+H 2 O) of the desulfurized solution was large at high sulfur dioxide pressure and reached the maximum of 15.7 ± 0.3 mol%. (author)

  9. Simulating and Optimizing Hydrogen Production by Low-pressure Autothermal Reforming of Natural Gas using Non-dominated Sorting Genetic Algorithm-II

    OpenAIRE

    Azarhoosh, M. J.; Ale Ebrahim, H.; Pourtarah, S. H.

    2016-01-01

    Conventional hydrogen production plants consist of natural gas steam reforming to CO+3H2 on Ni catalysts in a furnace, water-gas shift reaction for converting CO into CO2 and CO2 absorption. A new alternative method for highly endothermic steam reforming is autothermal reforming (steam reforming with air input to the reactor) without the need for external heating. In this study, hydrogen production by autothermal reforming for fuel cells (base case) was simulated based on a heterogeneous and ...

  10. Experimental Study of Na based Titanium Nanofluid-Water Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gunyeop; Kim, Soo Jae; Baek, Jehyun; Kim, Hyun Soo; Oh, Sun Ryung; Park, Hyun Sun; Kim, Moo Hwan [POSTECH, Pohang (Korea, Republic of)

    2015-10-15

    In KALIMER-600, a sodium-cooled fast reactor designed by KAERI, thermal energy is transported from high-temperature liquid Na (526 .deg. C at 0.1 MPa) to low temperature water (230 .deg. C at - 19.5 MPa) through a heat exchanger. If any leakage or rupture occurs during the operation of this heat exchanger, highly pressurized liquid water can penetrate into the liquid Na channels; this contact should instantly cause SWR. As reaction continues, liquid water is soon vaporized by pressure drop and huge amount of reaction heat. This generated water vapor expands large reaction area and increases sodium-water vapor reaction process. Therefore, the rapid generation of reaction product (like H{sub 2}) and water vapor increases the system pressure that can cause the system failure in SFR. To reduce this strong chemical reaction phenomena between Na and water, some we have focused on suppressing the chemical reactivity of liquid Na by dispersing nanoparticles (NPs). For the real application of NaTiNF, the pressure change induced by NaTiNF-water reaction is compared with Na-water reaction in the present study. NaTiNF contains 100nm of Ti NPs at 0.2 vol. %. The reaction rate of NaTiNF-water reaction is also investigated as reaction temperature increases. Sodium-water vapor reaction (SVR) will occur when an SWR accident occurs in SFR. In this manner, NaTiNF-water vapor reaction is experimentally performed for ensuring the suppression of chemical reactivity of NaTiNF in contact with water vapor. In the basic step for reducing risk of an SWR in SFR, we have experimentally verified the suppressed chemical reactivity of liquid sodium using Ti NPs through SWR and SVR experiments. In SWR, Na based titanium nanofluid (NaTiNF) shows lower pressure change than Na. As T{sub R} increases, P{sub max} in Na-water reaction increases while NaTiNF does not. The reaction rate of NaTiNF shows twice slower than that of Na. In SVR, NaTiNF shows slower temperature increase than Na. The distinct

  11. Ion-neutral gas reactions in a collision/reaction cell in inductively coupled plasma mass spectrometry: Correlation of ion signal decrease to kinetic rate constants

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Patrick J. [Trace Element Research Laboratory, School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210 (United States); Department of Chemistry, The Ohio State University, 120 18th Avenue, Columbus, OH 43210 (United States); Olesik, John W., E-mail: olesik.2@osu.edu [Trace Element Research Laboratory, School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210 (United States)

    2015-03-01

    Reaction gas flow rate dependent Ar{sub 2}{sup +} and Ar{sup +} signals are correlated to fundamental kinetic rate coefficients. A simple calculation, assuming that gas exits the reaction cell due only to effusion, is described to estimate the gas pressure in the reaction cell. The value of the product of the kinetic rate constant and the ion residence time in the reaction cell can be determined from experimental measurement of the decrease in an ion signal as a function of reaction gas flow rate. New kinetic rate constants are determined for the reaction of CH{sub 3}F with Ar{sup +} and Ar{sub 2}{sup +}. - Highlights: • How to determine pressure and the product of the kinetic rate constant times the ion residence time in reaction cell • Relate measured ICP-DRC-MS signals versus gas flow rate to kinetic rate constants measured previously using SIFT-MS • Describe how to determine previously unmeasured kinetic rate constants using ICP-DRC-MS.

  12. Biogeochemical interactions between of coal mine water and gas well cement

    Science.gov (United States)

    Gulliver, D. M.; Gardiner, J. B.; Kutchko, B. G.; Hakala, A.; Spaulding, R.; Tkach, M. K.; Ross, D.

    2017-12-01

    Unconventional natural gas wells drilled in Northern Appalachia often pass through abandoned coal mines before reaching the Marcellus or Utica formations. Biogeochemical interactions between coal mine waters and gas well cements have the potential to alter the cement and compromise its sealing integrity. This study investigates the mineralogical, geochemical, and microbial changes of cement cores exposed to natural coal mine waters. Static reactors with Class H Portland cement cores and water samples from an abandoned bituminous Pittsburgh coal mine simulated the cement-fluid interactions at relevant temperature for time periods of 1, 2, 4, and 6 weeks. Fluids were analyzed for cation and anion concentrations and extracted DNA was analyzed by 16S rRNA gene sequencing and shotgun sequencing. Cement core material was evaluated via scanning electron microscope. Results suggest that the sampled coal mine water altered the permeability and matrix mineralogy of the cement cores. Scanning electron microscope images display an increase in mineral precipitates inside the cement matrix over the course of the experiment. Chemistry results from the reaction vessels' effluent waters display decreases in dissolved calcium, iron, silica, chloride, and sulfate. The microbial community decreased in diversity over the 6-week experiment, with Hydrogenophaga emerging as dominant. These results provide insight in the complex microbial-fluid-mineral interactions of these environments. This study begins to characterize the rarely documented biogeochemical impacts that coal waters may have on unconventional gas well integrity.

  13. Analysis of acoustic data from UK sodium/water reaction test facilities

    International Nuclear Information System (INIS)

    Rowley, R.; Mcknight, J.A.; Airey, J.

    1990-01-01

    This paper describes acoustic measurements made during a number of sodium/water reaction experiments in the UK. The tests have included water and steam injections through both realistic (fatigue crack) defects and machined orifices and have covered a range of experimental conditions including those appropriate to the inlet and outlet regions of the EFR steam generators. Injection rates were typically in the range 0.1 to 30 g/s. Where possible, gas injections were also included in the test programme for comparison, since it is anticipated that a practical SGU acoustic leak detection system would include a facility for gas injections to allow system calibration, and to confirm transmission properties within the SGU. The test sections were instrumented with accelerometers on waveguides and in some cases included an under-sodium microphone situated about 300mm above the reaction zone. Tape recordings were made during the tests and used for detailed analysis off-line, although an audible output from one of the acoustic channels was used to monitor the progress of the injections and provide information for the rig operators. A comparison of the signal amplitudes measured during the experiments with typical reactor background noise was made and an estimate of the detection sensitivity of an acoustic monitoring system was deduced. 3 refs, 5 figs, 1 tab

  14. Chemical reactions of fission products with ethylene using the gas jet technique

    International Nuclear Information System (INIS)

    Contis, E.T.; Rengan, Krish; Griffin, Henry C.

    1994-01-01

    An understanding of the nature of the chemical reactions taking place between fission products and their carrier gases, and the designing of a fast separation procedure were the purposes of this investigation. Chemical reactions of short-lived (less than one minute half-life) fission products with carrier gases lead to various chemical species which can be separated in the gas phase. The Gas Jet Facility at the Ford Nuclear Reactor was used to study the yields of volatile selenium and bromine fission products of 235 U using a semi-automatic batch solvent extraction technique. Heptane and water were used as organic and inorganic solvents. A carrier gas mixture of ethylene to pre-purified nitrogen (1 : 3) was used to sweep the fission products from the target to the chemistry area for analysis. The results indicated that the volatile selenium products generated by the interaction of selenium fission fragments with ethylene were predominantly organic in nature (84%), possibly organoselenides. The selenium values were used to resolve the fractions of the bromine nuclides, which come from two major sources, viz., directly from fission and from the beta-decay of selenium. The data showed that the fractions of independent bromine fission products in the organic phase were much lower compared to selenium; the bromine values range from 10 to 22% and varied with mass number. Results indicated that the bromine products were inorganic in nature, as possibly hydrogen chloride. ((orig.))

  15. Alkylation of nitriles with gaseous carbenium ions. The ritter reaction in the dilute gas state

    International Nuclear Information System (INIS)

    Cacace, F.; Ciranni, G.; Giacomello, P.

    1982-01-01

    Radiolytically formed carbenium ions, such as sec-C 3 H 7 + , sec-C 4 H 9 + , and t-C 4 H 9 + , react in the gas phase with model aliphatic and aromatic nitriles yielding the corresponding nitrilium ions. The latter undergo efficient condensation with water that eventually leads to the formation of the corresponding N-alkylamides. The mechanism is analogous to the Ritter reaction in solution. The reactivity and selectivity of the gas-phase electrophilic attack on nitriles has been deduced from competition experiments under conditions that largely exclude the effects of solvation, ion pairing, etc., which complicate the interpretation of solution-chemistry measurements. 1 table

  16. Understanding and controlling chromaticity shift in LED devices

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Lynn; Mills, Karmann; Lamvik, Michael; Perkins, Curtis; Bobashev, Georgiy; Young, Joseph; Yaga, Robert; Johnson, Cortina

    2017-05-30

    Chromaticity shift in light-emitting diode (LED) devices arises from multiple mechanisms, and at least five different chromaticity shift modes (CSMs) have been identified to date. This paper focuses on the impacts of irreversible phosphor degradation as a cause of chromaticity shifts in LED devices. The nitride phosphors used to produce warm white LEDs are especially vulnerable to degradation due to thermal and chemical effects such as reactions with oxygen and water. As a result, LED devices utilizing these phosphors were found to undergo either a green shift or, less commonly, a red shift depending on the phosphor mix in the LED devices. These types of chromaticity shifts are classified as CSM-2 (green shift) and CSM-5 (red shift). This paper provides an overview of the kinetic processes responsible for green and red chromaticity shifts along with examples from accelerated stress testing of 6” downlights. Both CSMs appear to proceed through analogous mechanisms that are initiated at the surface of the phosphor. A green shift is produced by the surface oxidation of the nitride phosphor that changes the emission profile to lower wavelengths. As the surface oxidation reaction proceeds, reactant limitations slow the rate and bulk oxidation processes become more prevalent. We found that a red chromaticity shift arises from quenching of the green phosphor, also possibly due to surface reactions of oxygen, which shift the emission chromaticity in the red direction. In conclusion, we discuss the implications of these findings on projecting chromaticity.

  17. Desulfurization reaction of high sulfur content flue gas treated by electron beam

    International Nuclear Information System (INIS)

    Hirosawa, Shojiro; Suzuki, Ryoji; Aoki, Shinji; Kojima, Takuji; Hashimoto, Shoji

    2002-01-01

    Experiments of flue gas treatment by electron beam were carried out, using simulated ligniteburning flue gas containing SO 2 (5500 ppm), NO (390 ppm) and H 2 O (22%). Removal efficiency of SO 2 was more than 90% at a dose of 1-2 kGy. It shows applicability of electron beam for treatment of lignite-burning flue gas. Another removal reaction besides the radiation-induced radical reaction and the thermal reaction occurring without irradiation was suggested by the facts that removal of SO 2 by the radical reaction is only a few hundreds of ppm and the removal amounts by thermal reaction under irradiation is lower than a half of total desulfurization. The mechanism similar to thermal reaction was proposed, assuming simultaneous uptake reaction of SO 2 and NH 3 on the surface of liquid aerosol. It was suggested that ammonium nitrate having deliquescence relative humidity (DRH) of 60% at 25 deg C plays an important role in producing liquid aerosols. Decrease of DRH of ammonium nitrate with elevating temperature and with formation of double salt of ammonium sulfate results in enhancement of formation of liquid aerosols. (author)

  18. Geochemical evidence of water-soluble gas accumulation in the Weiyuan gas field, Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Shengfei Qin

    2016-01-01

    Full Text Available At present, there are several different opinions on the formation process of the Weiyuan gas field in the Sichuan Basin and the source of its natural gas. In view of the fact that the methane carbon isotope of the natural gas in the Weiyuan gas field is abnormally heavy, the geologic characteristics of gas reservoirs and the geochemical characteristics of natural gas were first analyzed. In the Weiyuan gas field, the principal gas reservoirs belong to Sinian Dengying Fm. The natural gas is mainly composed of methane, with slight ethane and trace propane. The gas reservoirs are higher in water saturation, with well preserved primary water. Then, it was discriminated from the relationship of H2S content vs. methane carbon isotope that the heavier methane carbon isotope of natural gas in this area is not caused by thermochemical sulfate reduction (TSR. Based on the comparison of methane carbon isotope in this area with that in adjacent areas, and combined with the tectonic evolution background, it is regarded that the natural gas in the Weiyuan gas field is mainly derived from water-soluble gas rather than be migrated laterally from adjacent areas. Some conclusions are made. First, since methane released from water is carbon isotopically heavier, the water-soluble gas accumulation after degasification results in the heavy methane carbon isotope of the gas produced from Weiyuan gas field. Second, along with Himalayan movement, great uplift occurred in the Weiyuan area and structural traps were formed. Under high temperature and high pressure, the gas dissolved in water experienced decompression precipitation, and the released natural gas accumulated in traps, consequently leading to the formation of Weiyuan gas field. Third, based on calculation, the amount of natural gas released from water which is entrapped in the Weiyuan gas field after the tectonic uplift is basically equal to the proved reserves of this field, confirming the opinion of water

  19. Direct gas-solid carbonation of serpentinite residues in the absence and presence of water vapor: a feasibility study for carbon dioxide sequestration.

    Science.gov (United States)

    Veetil, Sanoopkumar Puthiya; Pasquier, Louis-César; Blais, Jean-François; Cecchi, Emmanuelle; Kentish, Sandra; Mercier, Guy

    2015-09-01

    Mineral carbonation of serpentinite mining residue offers an environmentally secure and permanent storage of carbon dioxide. The strategy of using readily available mining residue for the direct treatment of flue gas could improve the energy demand and economics of CO2 sequestration by avoiding the mineral extraction and separate CO2 capture steps. The present is a laboratory scale study to assess the possibility of CO2 fixation in serpentinite mining residues via direct gas-solid reaction. The degree of carbonation is measured both in the absence and presence of water vapor in a batch reactor. The gas used is a simulated gas mixture reproducing an average cement flue gas CO2 composition of 18 vol.% CO2. The reaction parameters considered are temperature, total gas pressure, time, and concentration of water vapor. In the absence of water vapor, the gas-solid carbonation of serpentinite mining residues is negligible, but the residues removed CO2 from the feed gas possibly due to reversible adsorption. The presence of small amount of water vapor enhances the gas-solid carbonation, but the measured rates are too low for practical application. The maximum CO2 fixation obtained is 0.07 g CO2 when reacting 1 g of residue at 200 °C and 25 barg (pCO2 ≈ 4.7) in a gas mixture containing 18 vol.% CO2 and 10 vol.% water vapor in 1 h. The fixation is likely surface limited and restricted due to poor gas-solid interaction. It was identified that both the relative humidity and carbon dioxide-water vapor ratio have a role in CO2 fixation regardless of the percentage of water vapor.

  20. Modeling gravity effects on water retention and gas transport characteristics in plant growth substrates

    DEFF Research Database (Denmark)

    Deepagoda Thuduwe Kankanamge Kelum, Chamindu; Jones, Scott B.; Tuller, Markus

    2014-01-01

    utilization to conserve energy and to limit transport costs, native materials mined on Moon or Mars are of primary interest for plant growth media in a future outpost, while terrestrial porous substrates with optimal growth media characteristics will be useful for onboard plant growth during space missions....... Due to limited experimental opportunities and prohibitive costs, liquid and gas behavior in porous substrates under reduced gravity conditions has been less studied and hence remains poorly understood. Based on ground-based measurements, this study examined water retention, oxygen diffusivity and air...... that estimates the gas percolation threshold based on the pore size distribution. The model successfully captured measured data for all investigated media and demonstrated the implications of the poorly-understood shift in gas percolation threshold with improved gas percolation in reduced gravity. Finally, using...

  1. Suppression of the water splitting back reaction on GaN:ZnO photocatalysts loaded with core/shell cocatalysts, investigated using a μ-reactor

    DEFF Research Database (Denmark)

    Dionigi, Fabio; Vesborg, Peter Christian Kjærgaard; Pedersen, Thomas

    2012-01-01

    Using silicon-based l-reactors, we have studied the photocatalytic water splitting reaction and the catalytic back reaction on the same catalysts. GaN:ZnO without cocatalyst and loaded with Rh, Pt, Cr2O3/Rh, Cr2O3/Pt, and Rh–Cr mixed oxide has been tested for gas-phase photocatalytic water splitt...

  2. Fe/MCM-41 sylilated catalyst: structural changes determination during the Fischer-Tropsch reaction

    International Nuclear Information System (INIS)

    Bengoa, J. F.; Fellenz, N. A.; Cagnoli, M. V.; Cano, L. A.; Gallegos, N. G.; Alvarez, A. M.; Marchetti, S. G.

    2010-01-01

    Two Fe/MCM-41 systems, one of them sylilated, were obtained to be used as catalysts in Fischer-Tropsch reaction. They have more than 90% of the iron species located inside the support channels, leading to a narrow crystal size distribution accessible to reactive gases. The samples were characterized by X-ray diffraction, atomic absorption spectroscopy, N 2 adsorption, Moessbauer spectroscopy and Fourier transformer infrared spectroscopy. Moessbauer spectroscopy allowed us to demonstrate that the catalytic active species were the same in both catalysts. The only difference between them was the surface hydrophobicity, which decreases the 'water gas shift reaction' in the sylilated catalyst. Besides, this solid is more active for hydrocarbon production, with a lower methane yield.

  3. Modelling combustion reactions for gas flaring and its resulting emissions

    Directory of Open Access Journals (Sweden)

    O. Saheed Ismail

    2016-07-01

    Full Text Available Flaring of associated petroleum gas is an age long environmental concern which remains unabated. Flaring of gas maybe a very efficient combustion process especially steam/air assisted flare and more economical than utilization in some oil fields. However, it has serious implications for the environment. This study considered different reaction types and operating conditions for gas flaring. Six combustion equations were generated using the mass balance concept with varying air and combustion efficiency. These equations were coded with a computer program using 12 natural gas samples of different chemical composition and origin to predict the pattern of emission species from gas flaring. The effect of key parameters on the emission output is also shown. CO2, CO, NO, NO2 and SO2 are the anticipated non-hydrocarbon emissions of environmental concern. Results show that the quantity and pattern of these chemical species depended on percentage excess/deficiency of stoichiometric air, natural gas type, reaction type, carbon mass content, impurities, combustion efficiency of the flare system etc. These emissions degrade the environment and human life, so knowing the emission types, pattern and flaring conditions that this study predicts is of paramount importance to governments, environmental agencies and the oil and gas industry.

  4. Formation of gas bubbles in gas superheated water

    International Nuclear Information System (INIS)

    Finkelstein, Y.

    1984-05-01

    The phenomenon of bubbles formation in supersaturated solutions of gases in water is a transport process, the final result of which is a separation of phases. In spite of its widespread appearance in industry and in nature, no model exists that can explain it and predict the degree of supersaturation which a gas-water solution can tolerate before bubbles are formed. The objective of this study was to fill this gap, and indeed, an extensive experimental work was carried out, a model was established and simple but accurate means were developed for predicting the tolerable degree of supersaturation of gas-water solutions. The model is also capable of predicting quite accurately the activation phenomenon in water. Superheating and supercooling phenomena were also examined in the light of the new model. (author)

  5. Radical Reactions in the Gas Phase: Recent Development and Application in Biomolecules

    Directory of Open Access Journals (Sweden)

    Yang Gao

    2014-01-01

    Full Text Available This review summarizes recent literature describing the use of gas phase radical reactions for structural characterization of complex biomolecules other than peptides. Specifically, chemical derivatization, in-source chemical reaction, and gas phase ion/ion reactions have been demonstrated as effective ways to generate radical precursor ions that yield structural informative fragments complementary to those from conventional collision-induced dissociation (CID. Radical driven dissociation has been applied to a variety of biomolecules including peptides, nucleic acids, carbohydrates, and phospholipids. The majority of the molecules discussed in this review see limited fragmentation from conventional CID, and the gas phase radical reactions open up completely new dissociation channels for these molecules and therefore yield high fidelity confirmation of the structures of the target molecules. Due to the extensively studied peptide fragmentation, this review focuses only on nonpeptide biomolecules such as nucleic acids, carbohydrates, and phospholipids.

  6. Correlation between Gas Bubble Formation and Hydrogen Evolution Reaction Kinetics at Nanoelectrodes.

    Science.gov (United States)

    Chen, Qianjin; Luo, Long

    2018-04-17

    We report the correlation between H 2 gas bubble formation potential and hydrogen evolution reaction (HER) activity for Au and Pt nanodisk electrodes (NEs). Microkinetic models were formulated to obtain the HER kinetic information for individual Au and Pt NEs. We found that the rate-determining steps for the HER at Au and Pt NEs were the Volmer step and the Heyrovsky step, respectively. More interestingly, the standard rate constant ( k 0 ) of the rate-determining step was found to vary over 2 orders of magnitude for the same type of NEs. The observed variations indicate the HER activity heterogeneity at the nanoscale. Furthermore, we discovered a linear relationship between bubble formation potential ( E bubble ) and log( k 0 ) with a slope of 125 mV/decade for both Au and Pt NEs. As log ( k 0 ) increases, E bubble shifts linearly to more positive potentials, meaning NEs with higher HER activities form H 2 bubbles at less negative potentials. Our theoretical model suggests that such linear relationship is caused by the similar critical bubble formation condition for Au and Pt NEs with varied sizes. Our results have potential implications for using gas bubble formation to evaluate the HER activity distribution of nanoparticles in an ensemble.

  7. Can switching fuels save water? A life cycle quantification of freshwater consumption for Texas coal- and natural gas-fired electricity

    International Nuclear Information System (INIS)

    Grubert, Emily A; Beach, Fred C; Webber, Michael E

    2012-01-01

    Thermal electricity generation is a major consumer of freshwater for cooling, fuel extraction and air emissions controls, but the life cycle water impacts of different fossil fuel cycles are not well understood. Much of the existing literature relies on decades-old estimates for water intensity, particularly regarding water consumed for fuel extraction. This work uses contemporary data from specific resource basins and power plants in Texas to evaluate water intensity at three major stages of coal and natural gas fuel cycles: fuel extraction, power plant cooling and power plant emissions controls. In particular, the water intensity of fuel extraction is quantified for Texas lignite, conventional natural gas and 11 unconventional natural gas basins in Texas, including major second-order impacts associated with multi-stage hydraulic fracturing. Despite the rise of this water-intensive natural gas extraction method, natural gas extraction appears to consume less freshwater than coal per unit of energy extracted in Texas because of the high water intensity of Texas lignite extraction. This work uses new resource basin and power plant level water intensity data to estimate the potential effects of coal to natural gas fuel switching in Texas’ power sector, a shift under consideration due to potential environmental benefits and very low natural gas prices. Replacing Texas’ coal-fired power plants with natural gas combined cycle plants (NGCCs) would reduce annual freshwater consumption in the state by an estimated 53 billion gallons per year, or 60% of Texas coal power’s water footprint, largely due to the higher efficiency of NGCCs. (letter)

  8. Hydrophobic catalyst mixture for the isotopic exchange reaction between hydrogen and water

    Energy Technology Data Exchange (ETDEWEB)

    Paek, S.; Ahn, D. H.; Choi, H. J.; Kim, K. R.; Lee, M.; Yim, S. P.; Chung, H. [KAERI, Taejon (Korea, Republic of)

    2005-11-15

    Pt/SDBC catalyst, which is used for the hydrogen-water isotopic exchange reaction, was prepared. The various properties of the catalyst, such as the thermal stability, pore structure and the platinum dispersion, were investigated. A hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of the WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities.

  9. Hydrophobic catalyst mixture for the isotopic exchange reaction between hydrogen and water

    International Nuclear Information System (INIS)

    Paek, S.; Ahn, D. H.; Choi, H. J.; Kim, K. R.; Lee, M.; Yim, S. P.; Chung, H.

    2005-01-01

    Pt/SDBC catalyst, which is used for the hydrogen-water isotopic exchange reaction, was prepared. The various properties of the catalyst, such as the thermal stability, pore structure and the platinum dispersion, were investigated. A hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of the WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities

  10. Red-shifting and blue-shifting OH groups on metal oxide surfaces - towards a unified picture.

    Science.gov (United States)

    Kebede, Getachew G; Mitev, Pavlin D; Briels, Wim J; Hermansson, Kersti

    2018-05-09

    We analyse the OH vibrational signatures of 56 structurally unique water molecules and 34 structurally unique hydroxide ions in thin water films on MgO(001) and CaO(001), using DFT-generated anharmonic potential energy surfaces. We find that the OH stretching frequencies of intact water molecules on the surface are always downshifted with respect to the gas-phase species while the OH- groups are either upshifted or downshifted. Despite these differences, the main characteristics of the frequency shifts for all three types of surface OH groups (OHw, OsH and OHf) can be accounted for by one unified expression involving the in situ electric field from the surrounding environment, and the gas-phase molecular properties of the vibrating species (H2O or OH-). The origin behind the different red- and blueshift behaviour can be traced back to the fact that the molecular dipole moment of a gas-phase water molecule increases when an OH bond is stretched, but the opposite is true for the hydroxide ion. We propose that familiarity with the relations presented here will help surface scientists in the interpretation of vibrational OH spectra for thin water films on ionic crystal surfaces.

  11. Water relations and gas exchange in poplar and willow under water stress and elevated atmospheric CO2.

    Science.gov (United States)

    Johnson, Jon D; Tognetti, Roberto; Paris, Piero

    2002-05-01

    Predictions of shifts in rainfall patterns as atmospheric [CO2] increases could impact the growth of fast growing trees such as Populus spp. and Salix spp. and the interaction between elevated CO2 and water stress in these species is unknown. The objectives of this study were to characterize the responses to elevated CO2 and water stress in these two species, and to determine if elevated CO2 mitigated drought stress effects. Gas exchange, water potential components, whole plant transpiration and growth response to soil drying and recovery were assessed in hybrid poplar (clone 53-246) and willow (Salix sagitta) rooted cuttings growing in either ambient (350 &mgr;mol mol-1) or elevated (700 &mgr;mol mol-1) atmospheric CO2 concentration ([CO2]). Predawn water potential decreased with increasing water stress while midday water potentials remained unchanged (isohydric response). Turgor potentials at both predawn and midday increased in elevated [CO2], indicative of osmotic adjustment. Gas exchange was reduced by water stress while elevated [CO2] increased photosynthetic rates, reduced leaf conductance and nearly doubled instantaneous transpiration efficiency in both species. Dark respiration decreased in elevated [CO2] and water stress reduced Rd in the trees growing in ambient [CO2]. Willow had 56% lower whole plant hydraulic conductivity than poplar, and showed a 14% increase in elevated [CO2] while poplar was unresponsive. The physiological responses exhibited by poplar and willow to elevated [CO2] and water stress, singly, suggest that these species respond like other tree species. The interaction of [CO2] and water stress suggests that elevated [CO2] did mitigate the effects of water stress in willow, but not in poplar.

  12. Production of Synthetic Fuels by Co-Electrolysis of Steam and Carbon Dioxide

    DEFF Research Database (Denmark)

    Ebbesen, Sune; Graves, Christopher R.; Mogensen, Mogens Bjerg

    2009-01-01

    reactions, the equilibrium of the water-gas shift reaction is reached, and moreover, CO is produced via the water-gas shift reaction. The degradation observed when performing co-electrolysis in these SOCs occurs mainly at the Ni/YSZ cathode and may be a consequence of impurities in the gas stream, adsorbing......Co-electrolysis of H2O and CO2 was studied in solid oxide cells (SOCs) supported by nickel-/yittria-stabilized zirconia (Ni/YSZ) electrode. Polarization characterization indicates that electrochemical reduction of both CO2 and H2O occurs during co-electrolysis. In parallel with the electrochemical...

  13. Separation of water through gas hydrate formation

    DEFF Research Database (Denmark)

    Boch Andersen, Torben; Thomsen, Kaj

    2009-01-01

    Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goal...... of the project was to formulate an alternative separation concept, which can replace the traditional water evaporation process in the sugar production. Work with the separation concept showed that gas hydrates can be used for water separation. The process is not suitable for sugar production because of large...... volumes and the needs for high pressure. The process could be interesting for concentration of heat sensitive, high value products...

  14. Computational studies of atmospherically-relevant chemical reactions in water clusters and on liquid water and ice surfaces.

    Science.gov (United States)

    Gerber, R Benny; Varner, Mychel E; Hammerich, Audrey D; Riikonen, Sampsa; Murdachaew, Garold; Shemesh, Dorit; Finlayson-Pitts, Barbara J

    2015-02-17

    isolated defects where it involves formation of H3O(+)-acid anion contact ion pairs. This behavior is found in simulations of a model of the ice quasi-liquid layer corresponding to large defect concentrations in crystalline ice. The results are in accord with experiments. (iv) Ionization of acids on wet quartz. A monolayer of water on hydroxylated silica is ordered even at room temperature, but the surface lattice constant differs significantly from that of crystalline ice. The ionization processes of HCl and H2SO4 are of high yield and occur in a few picoseconds. The results are in accord with experimental spectroscopy. (v) Photochemical reactions on water and ice. These simulations require excited state quantum chemical methods. The electronic absorption spectrum of methyl hydroperoxide adsorbed on a large ice cluster is strongly blue-shifted relative to the isolated molecule. The measured and calculated adsorption band low-frequency tails are in agreement. A simple model of photodynamics assumes prompt electronic relaxation of the excited peroxide due to the ice surface. SEMD simulations support this, with the important finding that the photochemistry takes place mainly on the ground state. In conclusion, dynamics simulations using quantum chemical potentials are a useful tool in atmospheric chemistry of water media, capable of comparison with experiment.

  15. Poisoning by carbon monoxide in the hydrogen exchange reaction between deuterium gas and water preadsorbed on a platinum--alumina catalyst

    International Nuclear Information System (INIS)

    Iida, I.; Tamaru, K.

    1979-01-01

    Poisoning by carbon monoxide in the exchange reaction between deuterium and the water preadsorbed on a platinum--alumina catalyst was studied, by measuring not only the rate of reaction but also its kinetic behavior and the adsorption of reactants on the catalyst surface. The shape of the poisoning curve is closely associated with the kinetic behavior and exhibited an abrupt change on freezing the adsorbed water below 273 0 K. When the rate is proportional to deuterium pressure and independent of the amount of water adsorbed, the exchange rate dropped sharply by carbon monoxide adsorbed of a few percent coverage without any marked changes in the amount and the rate of hydrogen adsorption on the platinum surface. However, at temperatures lower than 273 0 K and at higher deuterium pressures, the rate depends not on the deuterium pressure but on the amount of water adsorbed. The migration of hydrogen in or through the adsorbed water is seemingly sufficiently suppressed by freezing to control the overall reaction rate. In this case, a small amount of adsorption of carbon monoxide did not show any toxicity, but then a steep poisoning started accompanying a change in the kinetic behavior. It was accordingly demonstrated that the mechanism of the reaction may be better understood by studying poisoning and measuring adsorption, overall rate, and kinetic behavior

  16. Relationships between water and gas chemistry in mature coalbed methane reservoirs of the Black Warrior Basin

    Science.gov (United States)

    Pashin, Jack C.; McIntyre-Redden, Marcella R.; Mann, Steven D.; Kopaska-Merkel, David C.; Varonka, Matthew S.; Orem, William H.

    2014-01-01

    Water and gas chemistry in coalbed methane reservoirs of the Black Warrior Basin reflects a complex interplay among burial processes, basin hydrodynamics, thermogenesis, and late-stage microbial methanogenesis. These factors are all important considerations for developing production and water management strategies. Produced water ranges from nearly potable sodium-bicarbonate water to hypersaline sodium-chloride brine. The hydrodynamic framework of the basin is dominated by structurally controlled fresh-water plumes that formed by meteoric recharge along the southeastern margin of the basin. The produced water contains significant quantities of hydrocarbons and nitrogen compounds, and the produced gas appears to be of mixed thermogenic-biogenic origin.Late-stage microbial methanogenesis began following unroofing of the basin, and stable isotopes in the produced gas and in mineral cements indicate that late-stage methanogenesis occurred along a CO2-reduction metabolic pathway. Hydrocarbons, as well as small amounts of nitrate in the formation water, probably helped nourish the microbial consortia, which were apparently active in fresh to hypersaline water. The produced water contains NH4+ and NH3, which correlate strongly with brine concentration and are interpreted to be derived from silicate minerals. Denitrification reactions may have generated some N2, which is the only major impurity in the coalbed gas. Carbon dioxide is a minor component of the produced gas, but significant quantities are dissolved in the formation water. Degradation of organic compounds, augmented by deionization of NH4+, may have been the principal sources of hydrogen facilitating late-stage CO2 reduction.

  17. Effects of water vapor on flue gas conditioning in the electric fields with corona discharge.

    Science.gov (United States)

    Liqiang, Qi; Yajuan, Zhang

    2013-07-15

    Sulfur dioxide (SO2) removal via pulsed discharge nonthermal plasma in the absence of ammonia was investigated to determine how electrostatic precipitators (ESPs) can effectively collect particulate matter less than 2.5μm in diameter from flue gas. SO2 removal increased as water vapor concentration increased. In a wet-type plasma reactor, directing a gas-phase discharge plasma toward the water film surface significantly enhanced the liquid-phase oxidation of HSO3(-) to SO4(2-). Comparisons of various absorbents revealed that the hydroxyl radical is a key factor in plasma-induced liquid-phase reactions. The resistivity, size distribution, and cohesive force of fly ash at different water vapor contents were measured using a Bahco centrifuge, which is a dust electrical resistivity test instrument, as well as a cohesive force test apparatus developed by the researchers. When water vapor content increased by 5%, fly ash resistivity in flue gas decreased by approximately two orders of magnitude, adhesive force and size increased, and specific surface area decreased. Therefore, ESP efficiency increased. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Assessment of a Hybrid Retrofit Gas Water Heater

    Energy Technology Data Exchange (ETDEWEB)

    Hoeschele, Marc [Davis Energy Group, Davis, CA (United States); Weitzel, Elizabeth [Davis Energy Group, Davis, CA (United States); Backman, Christine [Davis Energy Group, Davis, CA (United States)

    2017-02-28

    This project completed a modeling evaluation of a hybrid gas water heater that combines a reduced capacity tankless unit with a downsized storage tank. This product would meet a significant market need by providing a higher efficiency gas water heater solution for retrofit applications while maintaining compatibility with the 1/2 inch gas lines and standard B vents found in most homes. The TRNSYS simulation tool was used to model a base case 0.60 EF atmospheric gas storage water, a 0.82 EF non-condensing gas tankless water heater, an existing (high capacity) hybrid unit on the market, and an alternative hybrid unit with lower storage volume and reduced gas input requirements. Simulations were completed under a 'peak day' sizing scenario with 183 gpd hot water loads in a Minnesota winter climate case. Full-year simulations were then completed in three climates (ranging from Phoenix to Minneapolis) for three hot water load scenarios (36, 57, and 96 gpd). Model projections indicate that the alternative hybrid offers an average 4.5% efficiency improvement relative to the 0.60 EF gas storage unit across all scenarios modeled. The alternative hybrid water heater evaluated does show promise, but the current low cost of natural gas across much of the country and the relatively small incremental efficiency improvement poses challenges in initially building a market demand for the product.

  19. Assessment of a Hybrid Retrofit Gas Water Heater

    Energy Technology Data Exchange (ETDEWEB)

    Hoeschele, Marc [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Weitzel, Elizabeth [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Backman, Christine [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)

    2017-02-01

    This project completed a modeling evaluation of a hybrid gas water heater that combines a reduced capacity tankless unit with a downsized storage tank. This product would meet a significant market need by providing a higher efficiency gas water heater solution for retrofit applications while maintaining compatibility with the 1/2 inch gas lines and standard B vents found in most homes. The TRNSYS simulation tool was used to model a base case 0.60 EF atmospheric gas storage water, a 0.82 EF non-condensing gas tankless water heater, an existing (high capacity) hybrid unit on the market, and an alternative hybrid unit with lower storage volume and reduced gas input requirements. Simulations were completed under a 'peak day' sizing scenario with 183 gpd hot water loads in a Minnesota winter climate case. Full-year simulations were then completed in three climates (ranging from Phoenix to Minneapolis) for three hot water load scenarios (36, 57, and 96 gpd). Model projections indicate that the alternative hybrid offers an average 4.5% efficiency improvement relative to the 0.60 EF gas storage unit across all scenarios modeled. The alternative hybrid water heater evaluated does show promise, but the current low cost of natural gas across much of the country and the relatively small incremental efficiency improvement poses challenges in initially building a market demand for the product.

  20. Mechanisms and energetics of surface reactions at the copper-water interface. A critical literature review with implications for the debate on corrosion of copper in anoxic water

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Adam Johannes; Brinck, Tore [Applied Physical Chemistry, KTH Royal Inst. of Technology, Stockholm (Sweden)

    2012-06-15

    In order to make a critical analysis of the discussion of corrosion of copper in pure anoxic water it is necessary to understand the chemical reactivity at the copper-water interface. Even though the most fundamental issue, i.e. the nature and existence of a hypothetical product that is thermodynamically stable, is still under debate, it is clear that if anoxic corrosion really exists, it must be initiated through oxidative surface reactions at the copper-water interface. This report presents a survey of the peer reviewed literature on the reactivity of copper surfaces in water. Reactions discussed involve molecular adsorption of water, dissociation of the OH-bonds in adsorbed water molecules and hydroxyl groups, the disproportionation/synproportionation equilibrium between hydroxyl groups/hydroxide ions, water molecules and atomic oxygen, the surface diffusion of adsorbed species, and the formation of hydrogen gas (molecular hydrogen). Experimental, as well as theoretical (quantum chemical) studies are reviewed. It is concluded that a limited amount of hydrogen gas (H{sub 2}) should be formed as the result of dissociative water adsorption at certain copper surfaces. Quantitative estimates of the amounts of H2 that could form at the copper-water interface are made. Assuming that the water-cleavage/hydrogen-formation reaction proceeds on an ideal [110] or [100] surface until a hydroxyl monolayer (ML) is reached, the amount of H{sub 2} formed is {approx} 2.4 ng cm{sup -2} copper surface. Based on the literature cited, this is most likely possible, thermodynamically as well as kinetically. Although not proven, it is not unlikely that the reaction can proceed until an oxide ML is formed, which would give 4.8 ng cm{sup -2}. If the formation of an oxide ML is thermodynamically feasible the surface will probably react further, since Cu{sub 2}O(s) is known to activate and cleave the water molecule when it adsorbs at the Cu{sub 2}O(s) surface. Assuming the formation of a

  1. Laboratory Studies of Hydrogen Gas Generation Using the Cobalt Chloride Catalyzed Sodium Borohydride-Water Reaction

    Science.gov (United States)

    2015-07-01

    already use hydrogen for weather balloons . Besides cost, hydrogen has other advantages over helium. Hydrogen has more lift than helium, so larger...of water vapor entering the gas stream, and avoid damaging the balloon /aerostat (aerostats typically have an operational temperature range of -50 to...Aerostats: “Gepard” Tethered Aerostats with Mobile Mooring Systems. Available at http://rosaerosystems.com/aero/obj7. Accessed June 4, 2015. 11

  2. In Situ Environmental TEM in Imaging Gas and Liquid Phase Chemical Reactions for Materials Research.

    Science.gov (United States)

    Wu, Jianbo; Shan, Hao; Chen, Wenlong; Gu, Xin; Tao, Peng; Song, Chengyi; Shang, Wen; Deng, Tao

    2016-11-01

    Gas and liquid phase chemical reactions cover a broad range of research areas in materials science and engineering, including the synthesis of nanomaterials and application of nanomaterials, for example, in the areas of sensing, energy storage and conversion, catalysis, and bio-related applications. Environmental transmission electron microscopy (ETEM) provides a unique opportunity for monitoring gas and liquid phase reactions because it enables the observation of those reactions at the ultra-high spatial resolution, which is not achievable through other techniques. Here, the fundamental science and technology developments of gas and liquid phase TEM that facilitate the mechanistic study of the gas and liquid phase chemical reactions are discussed. Combined with other characterization tools integrated in TEM, unprecedented material behaviors and reaction mechanisms are observed through the use of the in situ gas and liquid phase TEM. These observations and also the recent applications in this emerging area are described. The current challenges in the imaging process are also discussed, including the imaging speed, imaging resolution, and data management. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Shale Gas Development and Drinking Water Quality.

    Science.gov (United States)

    Hill, Elaine; Ma, Lala

    2017-05-01

    The extent of environmental externalities associated with shale gas development (SGD) is important for welfare considerations and, to date, remains uncertain (Mason, Muehlenbachs, and Olmstead 2015; Hausman and Kellogg 2015). This paper takes a first step to address this gap in the literature. Our study examines whether shale gas development systematically impacts public drinking water quality in Pennsylvania, an area that has been an important part of the recent shale gas boom. We create a novel dataset from several unique sources of data that allows us to relate SGD to public drinking water quality through a gas well's proximity to community water system (CWS) groundwater source intake areas.1 We employ a difference-in-differences strategy that compares, for a given CWS, water quality after an increase in the number of drilled well pads to background levels of water quality in the geographic area as measured by the impact of more distant well pads. Our main estimate finds that drilling an additional well pad within 1 km of groundwater intake locations increases shale gas-related contaminants by 1.5–2.7 percent, on average. These results are striking considering that our data are based on water sampling measurements taken after municipal treatment, and suggest that the health impacts of SGD 1 A CWS is defined as the subset of public water systems that supplies water to the same population year-round. through water contamination remains an open question.

  4. Gas-phase ion/ion reactions of peptides and proteins: acid/base, redox, and covalent chemistries.

    Science.gov (United States)

    Prentice, Boone M; McLuckey, Scott A

    2013-02-01

    Gas-phase ion/ion reactions are emerging as useful and flexible means for the manipulation and characterization of peptide and protein biopolymers. Acid/base-like chemical reactions (i.e., proton transfer reactions) and reduction/oxidation (redox) reactions (i.e., electron transfer reactions) represent relatively mature classes of gas-phase chemical reactions. Even so, especially in regards to redox chemistry, the widespread utility of these two types of chemistries is undergoing rapid growth and development. Additionally, a relatively new class of gas-phase ion/ion transformations is emerging which involves the selective formation of functional-group-specific covalent bonds. This feature details our current work and perspective on the developments and current capabilities of these three areas of ion/ion chemistry with an eye towards possible future directions of the field.

  5. Enhanced Hydrogen Production Integrated with CO2 Separation in a Single-Stage

    Energy Technology Data Exchange (ETDEWEB)

    Mahesh Iyer; Shwetha Ramkumar; Liang-Shih Fan

    2006-09-30

    Enhancement in the production of high purity hydrogen from fuel gas, obtained from coal gasification, is limited by thermodynamics of the Water Gas Shift Reaction. However, this constraint can be overcome by concurrent water-gas shift (WGS) and carbonation reactions to enhance H{sub 2} production by incessantly driving the equilibrium-limited WGS reaction forward and in-situ removing the CO2 product from the gas mixture. The spent sorbent is then regenerated by calcining it to produce a pure stream of CO{sub 2} and CaO which can be reused. However while performing the cyclic carbonation and calcination it was observed that the CO{sub 2} released during the in-situ calcination causes the deactivation of the iron oxide WGS catalyst. Detailed understanding of the iron oxide phase diagram helped in developing a catalyst pretreatment procedure using a H{sub 2}/H{sub 2}O system to convert the deactivated catalyst back to its active magnetite (Fe{sub 3}O{sub 4}) form. The water gas shift reaction was studied at different temperatures, different steam to carbon monoxide ratios (S/C) 3:1, 2:1, 1:1 and different total pressures ranging from 0-300 psig. The combined water gas shift and carbonation reaction was investigated at temperatures ranging from 600-700C, S/C ratio of 3:1 to 1:1 and at different pressures of 0-300 psig and the calcium looping process was found to produce high purity hydrogen with in-situ CO{sub 2} capture.

  6. Tritium conversion in tritiated water: study of the involved reactions: a literature survey

    International Nuclear Information System (INIS)

    Ballereau, P.

    1987-10-01

    According to ICRP publication 30, hazards due to molecular tritium are not significant in comparison to hazards due to the oxidated form: tritiated water. It is thus important to know the kinetics of tritium/tritiated water conversion to obtain a realistic evaluation of the risks for the environment at level of present facilities and of future nuclear fusion facilities. Laboratory experiments in static contained conditions have shown that tritiated water is produced by two mechanisms: gas phase oxidation, hydrogen isotopic exchange with water. The periods found are relatively long and difficult to specify. In terrestrial atmosphere, the two mechanisms intervening in tritiated water formation are photochemical oxidation and biochemical reactions occurring in soil and in vegetation aerial parts. The corresponding periods are of some years for the first one, of some hours for the second one [fr

  7. Multiplicity dependence of matrix-induced frequency shifts for atomic transitions of the group 12 metals in rare gas solids

    International Nuclear Information System (INIS)

    Laursen, S.L.; Cartland, H.E.

    1991-01-01

    Atomic resonances of the group 12 metal atoms, Hg, Cd, and Zn, undergo frequency shifts from the gas phase atomic line when trapped in rare gas matrices of Ar, Kr, and Xe at 12 K. As expected, the shifts are approximately linear in polarizability of the rare gas, but the slope of this line depends on whether the transition in question is 1 P 1 left-arrow 1 S 0 or 3 P 1 left-arrow 1 S 0 . Thus the matrix-induced frequency shift is dependent on the singlet or triplet nature of the excited state as well as on the matrix material. This dependence on multiplicity is discussed in terms of interactions between the excited-state atomic orbitals and the matrix. The results are compared to matrix studies of other metals and to related gas-phase work on diatomic van der Waals complexes of group 12 metals with rare gases

  8. Calculation of relativistic and isotope shifts in Mg I

    International Nuclear Information System (INIS)

    Berengut, J.C.; Flambaum, V.V.; Kozlov, M.G.

    2005-01-01

    We present an ab initio method of calculation of the isotope and relativistic shifts in atoms with a few valence electrons. It is based on an energy calculation involving the combination of the configuration-interaction method and many-body perturbation theory. This work is motivated by analyses of quasar absorption spectra that suggest that the fine-structure constant α was smaller at an early epoch. Relativistic shifts are needed to measure this variation of α, while isotope shifts are needed to resolve systematic effects in this study. The isotope shifts can also be used to measure isotopic abundances in gas clouds in the early universe, which are needed to study nuclear reactions in stars and supernovae and test models of chemical evolution. This paper shows that the isotope shift in magnesium can be calculated to very high precision using our method

  9. Contribution to the modelling of gas-solid reactions and reactors

    International Nuclear Information System (INIS)

    Patisson, F.

    2005-09-01

    Gas-solid reactions control a great number of major industrial processes involving matter transformation. This dissertation aims at showing that mathematical modelling is a useful tool for both understanding phenomena and optimising processes. First, the physical processes associated with a gas-solid reaction are presented in detail for a single particle, together with the corresponding available kinetic grain models. A second part is devoted to the modelling of multiparticle reactors. Different approaches, notably for coupling grain models and reactor models, are illustrated through various case studies: coal pyrolysis in a rotary kiln, production of uranium tetrafluoride in a moving bed furnace, on-grate incineration of municipal solid wastes, thermogravimetric apparatus, nuclear fuel making, steel-making electric arc furnace. (author)

  10. MOLECULAR SPECTROSCPY AND REACTIONS OF ACTINIDES IN THE GAS PHASE AND CRYOGENIC MATRICES

    Energy Technology Data Exchange (ETDEWEB)

    Heaven, Michael C.; Gibson, John K.; Marcalo, Joaquim

    2009-02-01

    In this chapter we review the spectroscopic data for actinide molecules and the reaction dynamics for atomic and molecular actinides that have been examined in the gas phase or in inert cryogenic matrices. The motivation for this type of investigation is that physical properties and reactions can be studied in the absence of external perturbations (gas phase) or under minimally perturbing conditions (cryogenic matrices). This information can be compared directly with the results from high-level theoretical models. The interplay between experiment and theory is critically important for advancing our understanding of actinide chemistry. For example, elucidation of the role of the 5f electrons in bonding and reactivity can only be achieved through the application of experimentally verified theoretical models. Theoretical calculations for the actinides are challenging due the large numbers of electrons that must be treated explicitly and the presence of strong relativistic effects. This topic has been reviewed in depth in Chapter 17 of this series. One of the goals of the experimental work described in this chapter has been to provide benchmark data that can be used to evaluate both empirical and ab initio theoretical models. While gas-phase data are the most suitable for comparison with theoretical calculations, there are technical difficulties entailed in generating workable densities of gas-phase actinide molecules that have limited the range of species that have been characterized. Many of the compounds of interest are refractory, and problems associated with the use of high temperature vapors have complicated measurements of spectra, ionization energies, and reactions. One approach that has proved to be especially valuable in overcoming this difficulty has been the use of pulsed laser ablation to generate plumes of vapor from refractory actinide-containing materials. The vapor is entrained in an inert gas, which can be used to cool the actinide species to room

  11. Application of laser diagnostics to sodium-water chemical reaction field

    International Nuclear Information System (INIS)

    Deguchi, Yoshihiro; Tamura, Kenta; Muranaka, Ryota; Kusano, Koji; Kikuchi, Shin; Kurihara, Akikazu

    2013-01-01

    In a sodium-cooled fast reactor (SFR), liquid sodium is used as a heat transfer fluid because of its excellent heat transport capability. On the other hand, it has strong chemical reactivity with water vapor. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow by a breach of heat transfer tubes in a steam generator. Therefore the study on sodium-water chemical reactions is of paramount importance for safety reasons. This study aims to clarify the sodium-water reaction mechanisms using laser diagnostics. The sodium-water counter-flow reactions were measured using laser diagnostics such as laser induced fluorescence, CARS, Raman scattering and photo-fragmentation. The measurement results show that the sodium-water reaction proceeds mainly by the reaction Na + H 2 O → NaOH + H and the main product is NaOH in this reaction. Its forward and backward reaction rates tend to balance with each other and the whole reaction rate reduces as temperature increases. (author)

  12. Reaction between laser ablation plume and ambient gas studied by laser-induced fluorescence imaging spectroscopy

    International Nuclear Information System (INIS)

    Sasaki, K; Watarai, H

    2007-01-01

    We visualized the density distributions of C 2 (plume), NO (ambient gas), and CN (reaction product) when a graphite target was ablated by irradiating YAG laser pulses at wavelengths of 1064 and 355 nm in ambient gas mixture of NO and He. It has been shown by the density distributions of C 2 and NO that the expansion of the plume removes the ambient gas and the plume and the ambient gas locate exclusively in both the cases at 1064 and 355 nm. A high CN density was observed at the interface between the plume and the ambient gas at 1064 nm, which is reasonable since chemical reactions between the plume and the ambient gas may occur only at their interface. On the other hand, in the case at 355 nm, we observed considerable CN inside the plume, indicating that the chemical reaction processes in the laser ablation at 355 nm is different from that expected from the density distributions of the plume and the ambient gas

  13. Gas consumption for water heating in the Netherlands

    International Nuclear Information System (INIS)

    Bos, R.; Weegink, R.

    1995-01-01

    In 1994 the total gas consumption of Dutch households increased slightly. This is mainly due to an increase in the number of occupied homes by about 75,000, an advancing penetration of gas-fired tap water heaters and a marginal increase in gas consumption for space heating. Another striking feature is the stabilisation of gas consumption of an average household for hot water purposes, since it decreased in 1992 and 1993 by 3% and 4,5% respectively. The so-called Dutch BAK (basic survey of the small-scale gas consumption) study also shows that the penetration of gas appliances with higher outputs and changing water tapping behaviour, the major reasons for consumption increases in the previous years, have changed only moderately. Gas consumption for cooking purposes remained almost stable, though. 7 tabs., 1 ill

  14. Evaluating the energy and CO2 emissions impacts of shifts in residential water heating in the United States

    International Nuclear Information System (INIS)

    Sanders, Kelly T.; Webber, Michael E.

    2015-01-01

    Water heating represented nearly 13% of 2010 residential energy consumption making it an important target for energy conservation efforts. The objective of this work is to identify spatially-resolved strategies for energy conservation, since little analysis has been done to identify how regional characteristics affect the energy consumed for water heating. We present a first-order thermodynamic analysis, utilizing ab initio calculations and regression methods, to quantify primary energy consumption and CO 2 emissions with regional specificity by considering by considering local electricity mixes, heat rates, solar radiation profiles, heating degrees days, and water heating unit sales for 27 regions of the US. Results suggest that shifting from electric towards natural gas or solar water heating offered primary energy and CO 2 emission reductions in most US regions, but these reductions varied considerably according to regional electricity mix and solar resources. We find that regions that would benefit most from technology transitions, are often least likely to switch due to limited economic incentives. Our results suggest that federal energy factor metrics, which ignore upstream losses in power generation, are insufficient in informing consumers about the energy performance of residential end use appliances. - Highlights: • US energy factor ratings for water heaters ignore upstream losses. • Switching from electric storage water heating reduces CO 2 emissions in most US regions. • Regions with greatest potential for CO 2 avoidance are least likely to shift technologies. • Benefits vary significantly according to climate and regional electricity fuel mix

  15. Electrochemistry of single nanobubbles. Estimating the critical size of bubble-forming nuclei for gas-evolving electrode reactions.

    Science.gov (United States)

    German, Sean R; Edwards, Martin A; Chen, Qianjin; Liu, Yuwen; Luo, Long; White, Henry S

    2016-12-12

    In this article, we address the fundamental question: "What is the critical size of a single cluster of gas molecules that grows and becomes a stable (or continuously growing) gas bubble during gas evolving reactions?" Electrochemical reactions that produce dissolved gas molecules are ubiquitous in electrochemical technologies, e.g., water electrolysis, photoelectrochemistry, chlorine production, corrosion, and often lead to the formation of gaseous bubbles. Herein, we demonstrate that electrochemical measurements of the dissolved gas concentration, at the instant prior to nucleation of an individual nanobubble of H 2 , N 2 , or O 2 at a Pt nanodisk electrode, can be analyzed using classical thermodynamic relationships (Henry's law and the Young-Laplace equation - including non-ideal corrections) to provide an estimate of the size of the gas bubble nucleus that grows into a stable bubble. We further demonstrate that this critical nucleus size is independent of the radius of the Pt nanodisk employed (gas. For example, the measured critical surface concentration of H 2 of ∼0.23 M at the instant of bubble formation corresponds to a critical H 2 nucleus that has a radius of ∼3.6 nm, an internal pressure of ∼350 atm, and contains ∼1700 H 2 molecules. The data are consistent with stochastic fluctuations in the density of dissolved gas, at or near the Pt/solution interface, controlling the rate of bubble nucleation. We discuss the growth of the nucleus as a diffusion-limited process and how that process is affected by proximity to an electrode producing ∼10 11 gas molecules per second. Our study demonstrates the advantages of studying a single-entity, i.e., an individual nanobubble, in understanding and quantifying complex physicochemical phenomena.

  16. Possible techniques for decontamination of natural gas from gas wells stimulated by a nuclear explosion

    Energy Technology Data Exchange (ETDEWEB)

    Wethington, Jr, John A [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

    1970-05-15

    Decontamination of the products from gas wells stimulated by nuclear explosions requires the removal of T, present as HT, CH{sub 3}T, C{sub 2}H{sub 5}T, etc., and {sup 85}Kr from the production stream. Flaring of large volumes of gas from the Gasbuggy well led to the replacement of radioactive cavity gas with inactive formation gas, but this would not be a satisfactory production procedure because it releases T and {sup 85}Kr into the atmosphere and wastes large amounts of product gas. Exchange reactions appear to offer promise for removing the tritium. For example, water or steam flowing countercurrent to tritiated gas in the presence of a suitable catalyst can participate in the exchange reactions CH{sub 3}T + H{sub 2}O {r_reversible} CH{sub 4} + HTO, HT + H{sub 2}O {r_reversible} H{sub 2} + HTO, resulting in the transfer of T from gas into water. Other possibilities for utilizing exchange reactions include exchange of the gas with ethylene glycol used in the gas dryer, with silicate rocks introduced into the gas stream, or with a countercurrent stream of NH{sub 3} or H{sub 2}S. As another approach, use of the contaminated gas for the manufacture of ammonia synthesis gas has potential for removal of both T and {sup 85}Kr. (author)

  17. Reaction between infusion water and methane

    Energy Technology Data Exchange (ETDEWEB)

    Ettinger, I L

    1977-09-01

    This paper discusses the effect of infused water on the initial gas emission rate and on the pore structure of the coal. Water traps methane in micro-pores, so that lengthy periods are needed for the methane to penetrate large voids and cavities.

  18. Heterogeneous reactions and aerosol formation in flue gas cleaning by electron beam

    International Nuclear Information System (INIS)

    Baumann, W.; Jordan, S.; Leichsenring, C.H.; Maetzing, H.; Paur, H.R.; Schikarski, W.

    1990-08-01

    The electron beam dry scrubbing process is a simultaneous method for the removal of SO 2 and NO x from flue gas. By electron irradiation radicals (OH, O 2 H, O) are formed from the main flue gas components which oxidize NO x and SO 2 into the acids HNO 3 and H 2 SO 4 . These are then neutralized by the injection of NH 3 . A submicron aerosol consisting of ammonium salts is formed which is filtered from the offgas. The main pathways of the gas phase chemistry and product formation have been elucidated by experimental and theoretical studies. Back reactions which occur in the gas and the particle phase limit the energy efficiency of the process. By recirculation of irradiated gas into the reaction vessel (multiple irradiation) a significant improvement of removal yields was obtained. This enhancement of the energy efficiency requires the removal of products between the irradiation steps. Studies show that the material balance is complete. Deficits in the N and S balance of the process are due to the additional formation of molecular nitrogen and the deposition of ammonium sulfate in the ducts. Aerosol formation participates only with 30% in the material balance. The remaining 70% of the product are formed by surface reactions in the filter cake (40%) and in the ducts (30%). (orig.) With 38 figs., 29 tabs [de

  19. H2 gas pressure calculation of FPM capsule failure at RSG-GAS reactor core

    International Nuclear Information System (INIS)

    Hastuti, Endiah Puji; Sunaryo, Geni Rina

    2002-01-01

    RSG-GAS has been irradiated FPM capsule for 236 times, one of those i.e. capsule number 228 has failure. The one of root cause of failure possibility is radiolysis reaction can be occurred in FPM capsule when it is filled with water during irradiation in the reactor core. The safety analysis of the radiolysis reaction in the capsule has been done. The oc cumulative hydrogen gas production can cause high pressure in the capsule then a mechanical damage occurred. The analysis was done at 10 MW of reactor power which equivalent with neutron flux of 0,6929 x 10 1 4 n/cm 2 sec and γ dose rate of 0,63x10 9 rad/hour. The assumption is the capsule is filled with water at maximum volume, i.e. 176.67 ml. The results of calculation showed that radiolysis reaction with γ and neutron produce hydrogen gas for nominal flow rate each are 494 atm and 19683 atm for γ and neutron radiolysis, respectively. H 2 gas pressure for 5% flow rate each are 723 atm. and 25772 atm., for γ and neutron radiolysis, respectively. The changing of the operation condition due to radiolysis together with one way valve' phenomena, can be produce hydrogen gas from water during irradiation in the reactor core and can be the one of root cause of capsule failure. This analysis recommended the FPM capsule preparation must be guaranteed no water or/and there is no possibility of water immersion in the capsule during irradiation in the core by more accurate leak test

  20. Experimental investigation of solid sodium-water reaction: tests results and phenomenological analysis

    International Nuclear Information System (INIS)

    Daudin, K.; Beauchamp, F.; Proust, C.

    2014-01-01

    Sodium-Water Reaction (SWR) is an issue one has to be capable to deal with for the next generation of nuclear reactors (SFR for GEN IV). The background of these experiments is the improvement of safety demonstration regarding SWR in an open volume. This experimental campaign is conducted at the CEA Cadarache inside a cylindrical reactor filled with inert gas. The sodium is inside a loading pot and water comes into contact by immersion. SWR and its physical effects are followed by different pressure and temperature sensors. The results show a limit to the overpressure increasing sodium mass. Global assessment of physical effects of SWR contributes to put forward the relative nature of phenomena with geometric configuration, and the importance of scale effects. (authors)

  1. Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chen Li [Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Goettingen (Germany); Ueta, Hirokazu; Beck, Rainer D. [Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Federale de Lausanne (Switzerland); Bisson, Regis [Aix-Marseille Universite, PIIM, CNRS, UMR 7345, 13397 Marseille (France)

    2013-05-15

    We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S({theta}). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface.

  2. Panorama 2011: Unconventional gas and water

    International Nuclear Information System (INIS)

    Vially, R.

    2011-01-01

    For a number of years now, the rapid development of unconventional gas use in North America has been revolutionising the natural gas market. This generic term refers to several production types, such as tight gas, shale gas and coal bed methane. What they have in common is that the rock needs to be 'stimulated' in order to extract gas from it that can be commercially produced. These methods (horizontal drilling, hydraulic fracturing) all involve sensible management of the water needed for gas production. (author)

  3. On the study of catalytic membrane reactor for water detritiation: Modeling approach

    Energy Technology Data Exchange (ETDEWEB)

    Liger, Karine, E-mail: karine.liger@cea.fr [CEA, DEN, DTN/SMTA/LIPC Cadarache, Saint Paul-lez-Durance F-13108 (France); Mascarade, Jérémy [CEA, DEN, DTN/SMTA/LIPC Cadarache, Saint Paul-lez-Durance F-13108 (France); Joulia, Xavier; Meyer, Xuan-Mi [Université de Toulouse, INPT, UPS, Laboratoire de Génie Chimique, 4, Allée Emile Monso, Toulouse F-31030 (France); CNRS, Laboratoire de Génie Chimique, Toulouse F-31030 (France); Troulay, Michèle; Perrais, Christophe [CEA, DEN, DTN/SMTA/LIPC Cadarache, Saint Paul-lez-Durance F-13108 (France)

    2016-11-01

    Highlights: • Experimental results for the conversion of tritiated water (using deuterium as a simulant of tritium) by means of a catalytic membrane reactor in view of tritium recovery. • Phenomenological 2D model to represent catalytic membrane reactor behavior including the determination of the compositions of gaseous effluents. • Good agreement between the simulation results and experimental measurements performed on the dedicated facility. • Explanation of the unexpected behavior of the catalytic membrane reactor by the modeling results and in particular the gas composition estimation. - Abstract: In the framework of tritium recovery from tritiated water, efficiency of packed bed membrane reactors have been successfully demonstrated. Thanks to protium isotope swamping, tritium bonded water can be recovered under the valuable Q{sub 2} form (Q = H, D or T) by means of isotope exchange reactions occurring on catalyst surface. The use of permselective Pd-based membrane allows withdrawal of reactions products all along the reactor, and thus limits reverse reaction rate to the benefit of the direct one (shift effect). The reactions kinetics, which are still little known or unknown, are generally assumed to be largely greater than the permeation ones so that thermodynamic equilibriums of isotope exchange reactions are generally assumed. This paper proposes a new phenomenological 2D model to represent catalytic membrane reactor behavior with the determination of gas effluents compositions. A good agreement was obtained between the simulation results and experimental measurements performed on a dedicated facility. Furthermore, the gas composition estimation permits to interpret unexpected behavior of the catalytic membrane reactor. In the next future, further sensitivity analysis will be performed to determine the limits of the model and a kinetics study will be conducted to assess the thermodynamic equilibrium of reactions.

  4. On the study of catalytic membrane reactor for water detritiation: Modeling approach

    International Nuclear Information System (INIS)

    Liger, Karine; Mascarade, Jérémy; Joulia, Xavier; Meyer, Xuan-Mi; Troulay, Michèle; Perrais, Christophe

    2016-01-01

    Highlights: • Experimental results for the conversion of tritiated water (using deuterium as a simulant of tritium) by means of a catalytic membrane reactor in view of tritium recovery. • Phenomenological 2D model to represent catalytic membrane reactor behavior including the determination of the compositions of gaseous effluents. • Good agreement between the simulation results and experimental measurements performed on the dedicated facility. • Explanation of the unexpected behavior of the catalytic membrane reactor by the modeling results and in particular the gas composition estimation. - Abstract: In the framework of tritium recovery from tritiated water, efficiency of packed bed membrane reactors have been successfully demonstrated. Thanks to protium isotope swamping, tritium bonded water can be recovered under the valuable Q_2 form (Q = H, D or T) by means of isotope exchange reactions occurring on catalyst surface. The use of permselective Pd-based membrane allows withdrawal of reactions products all along the reactor, and thus limits reverse reaction rate to the benefit of the direct one (shift effect). The reactions kinetics, which are still little known or unknown, are generally assumed to be largely greater than the permeation ones so that thermodynamic equilibriums of isotope exchange reactions are generally assumed. This paper proposes a new phenomenological 2D model to represent catalytic membrane reactor behavior with the determination of gas effluents compositions. A good agreement was obtained between the simulation results and experimental measurements performed on a dedicated facility. Furthermore, the gas composition estimation permits to interpret unexpected behavior of the catalytic membrane reactor. In the next future, further sensitivity analysis will be performed to determine the limits of the model and a kinetics study will be conducted to assess the thermodynamic equilibrium of reactions.

  5. Solar-assisted gas-energy water-heating feasibility for apartments

    Science.gov (United States)

    Davis, E. S.

    1975-01-01

    Studies of residential energy use, solar-energy technology for buildings, and the requirements for implementing technology in the housing industry led to a project to develop a solar water heater for apartments. A design study for a specific apartment was used to establish a solar water-heater cost model which is based on plumbing contractor bids and manufacturer estimates. The cost model was used to size the system to minimize the annualized cost of hot water. The annualized cost of solar-assisted gas-energy water heating is found to be less expensive than electric water heating but more expensive than gas water heating. The feasibility of a natural gas utility supplying the auxiliary fuel is evaluated. It is estimated that gas-utilizing companies will find it profitable to offer solar water heating as part of a total energy service option or on a lease basis when the price of new base-load supplies of natural gas reaches $2.50-$3.00 per million Btu.

  6. Method and apparatus for controlling gas evolution from chemical reactions

    Science.gov (United States)

    Skorpik, James R.; Dodson, Michael G.

    1999-01-01

    The present invention is directed toward monitoring a thermally driven gas evolving chemical reaction with an acoustic apparatus. Signals from the acoustic apparatus are used to control a heater to prevent a run-away condition. A digestion module in combination with a robotic arm further automate physical handling of sample material reaction vessels. The invention is especially useful for carrying out sample procedures defined in EPA Methods SW-846.

  7. Gas-phase ion-molecule reactions and high-pressure mass spectrometer, 1

    International Nuclear Information System (INIS)

    Hiraoka, Kenzo

    1977-01-01

    The reasons for the fact that the research in gas-phase ion-molecule reactions, to which wide interest is shown, have greatly contributed to the physical and chemical fields are that, first it is essential in understanding general phenomena concerning ions, second, it can furnish many unique informations in the dynamics of chemical reactions, and third, usefulness of '' chemical ionization'' methods has been established as its application to chemical analysis. In this review, the history and trend of studies and equipments in gas-phase ion-molecule reactions are surveyed. The survey includes the chemical ionization mass spectrometer for simultaneously measuring the positive and negative ions utilizing a quadrupole mass spectrometer presented by Hunt and others, flowing afterglow method derived from the flowing method which traces neutral chemical species mainly optically, ion cyclotron resonance mass spectrometer, trapped ion mass spectrometer and others. Number of reports referred to ion-molecule reactions issued during the last one year well exceeds the total number of reports concerning mass spectrometers presented before 1955. This truly shows how active the research and development are in this field. (Wakatsuki, Y.)

  8. Water Gas Shift Reaction with A Single Stage Low Temperature Membrane Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ciora, Richard J [Media and Process Technology Inc., Pittsburgh, PA (United States); Liu, Paul KT [Media and Process Technology Inc., Pittsburgh, PA (United States)

    2013-12-31

    Palladium membrane and Palladium membrane reactor were developed under this project for hydrogen separation and purification for fuel cell applications. A full-scale membrane reactor was designed, constructed and evaluated for the reformate produced from a commercial scale methanol reformer. In addition, the Pd membrane and module developed from this project was successfully evaluated in the field for hydrogen purification for commercial fuel cell applications.

  9. Treatment of Oil & Gas Produced Water.

    Energy Technology Data Exchange (ETDEWEB)

    Dwyer, Brian P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-02-01

    Production of oil and gas reserves in the New Mexico Four Corners Region results in large volumes of "produced water". The common method for handling the produced water from well production is re-injection in regulatory permitted salt water disposal wells. This is expensive (%7E $5/bbl.) and does not recycle water, an ever increasingly valuable commodity. Previously, Sandia National Laboratories and several NM small business tested pressure driven membrane-filtration techniques to remove the high TDS (total dissolved solids) from a Four Corners Coal Bed Methane produced water. Treatment effectiveness was less than optimal due to problems with pre-treatment. Inadequate pre-treatment allowed hydrocarbons, wax and biological growth to foul the membranes. Recently, an innovative pre-treatment scheme using ozone and hydrogen peroxide was pilot tested. Results showed complete removal of hydrocarbons and the majority of organic constituents from a gas well production water. ACKNOWLEDGEMENTS This report was made possible through funding from the New Mexico Small Business Administration (NMSBA) Program at Sandia National Laboratories. Special thanks to Juan Martinez and Genaro Montoya for guidance and support from project inception to completion. Also, special thanks to Frank McDonald, the small businesses team POC, for laying the ground work for the entire project; Teresa McCown, the gas well owner and very knowledgeable- fantastic site host; Lea and Tim Phillips for their tremendous knowledge and passion in the oil & gas industry.; and Frank Miller and Steve Addleman for providing a pilot scale version of their proprietary process to facilitate the pilot testing.

  10. ADVANCED STRIPPER GAS PRODUCED WATER REMEDIATION

    International Nuclear Information System (INIS)

    Ray W. Sheldon

    2001-01-01

    Natural gas and oil production from stripper wells also produces water contaminated with hydrocarbons, and in most locations, salts and trace elements. The hydrocarbons are not generally present in concentrations that allow the operator to economically recover these liquids. Produced liquids, (stripper gas water) which are predominantly water, present the operator with two options; purify the water to acceptable levels of contaminates, or pay for the disposal of the water. The project scope involves testing SynCoal as a sorbent to reduce the levels of contamination in stripper gas well produced water to a level that the water can be put to a productive use. Produced water is to be filtered with SynCoal, a processed sub-bituminous coal. It is expected that the surface area of and in the SynCoal would sorb the hydrocarbons and other contaminates and the effluent would be usable for agricultural purposes. Test plan anticipates using two well locations described as being disparate in the level and type of contaminates present. The loading capacity and the rate of loading for the sorbent should be quantified in field testing situations which include unregulated and widely varying liquid flow rates. This will require significant flexibility in the initial stages of the investigation. The scope of work outlined below serves as the guidelines for the testing of SynCoal carbon product as a sorbent to remove hydrocarbons and other contaminants from the produced waters of natural gas wells. A maximum ratio of 1 lb carbon to 100 lbs water treated is the initial basis for economic design. While the levels of contaminants directly impact this ratio, the ultimate economics will be dictated by the filter servicing requirements. This experimental program is intended to identify those treatment parameters that yield the best technological practice for a given set of operating conditions. The goal of this research is to determine appropriate guidelines for field trials by accurately

  11. A proposed abiotic reaction scheme for hydroxylamine and monochloramine under chloramination relevant drinking water conditions.

    Science.gov (United States)

    Wahman, David G; Speitel, Gerald E; Machavaram, Madhav V

    2014-09-01

    Drinking water monochloramine (NH2Cl) use may promote ammonia-oxidizing bacteria (AOB). AOB use (i) ammonia monooxygenase for biological ammonia (NH3) oxidation to hydroxylamine (NH2OH) and (ii) hydroxylamine oxidoreductase for NH2OH oxidation to nitrite. NH2Cl and NH2OH may react, providing AOB potential benefits and detriments. The NH2Cl/NH2OH reaction would benefit AOB by removing the disinfectant (NH2Cl) and releasing their growth substrate (NH3), but the NH2Cl/NH2OH reaction would also provide a possible additional inactivation mechanism besides direct NH2Cl reaction with cells. Because biological NH2OH oxidation supplies the electrons required for biological NH3 oxidation, the NH2Cl/NH2OH reaction provides a direct mechanism for NH2Cl to inhibit NH3 oxidation, starving the cell of reductant by preventing biological NH2OH oxidation. To investigate possible NH2Cl/NH2OH reaction implications on AOB, an understanding of the underlying abiotic reaction is first required. The present study conducted a detailed literature review and proposed an abiotic NH2Cl/NH2OH reaction scheme (RS) for chloramination relevant drinking water conditions (μM concentrations, air saturation, and pH 7-9). Next, RS literature based kinetics and end-products were evaluated experimentally between pHs 7.7 and 8.3, representing (i) the pH range for future experiments with AOB and (ii) mid-range pHs typically found in chloraminated drinking water. In addition, a (15)N stable isotope experiment was conducted to verify nitrous oxide and nitrogen gas production and their nitrogen source. Finally, the RS was slightly refined using the experimental data and an AQUASIM implemented kinetic model. A chloraminated drinking water relevant RS is proposed and provides the abiotic reaction foundation for future AOB biotic experiments. Published by Elsevier Ltd.

  12. Effects of water vapor on flue gas conditioning in the electric fields with corona discharge

    Energy Technology Data Exchange (ETDEWEB)

    Liqiang, QI, E-mail: qi_liqiang@163.com; Yajuan, Zhang

    2013-07-15

    Highlights: • The influence mechanism of water vapor humidification on SO{sub 2} oxidation was analyzed. •The effects of water vapor on the specific resistance in fly ash in ESPs were reported. • The effects of water vapor on the size distribution and specific surface area of fly ash were discussed. • The adhesive characteristic of fly ash in different water vapor was experimented. -- Abstract: Sulfur dioxide (SO{sub 2}) removal via pulsed discharge nonthermal plasma in the absence of ammonia was investigated to determine how electrostatic precipitators (ESPs) can effectively collect particulate matter less than 2.5 μm in diameter from flue gas. SO{sub 2} removal increased as water vapor concentration increased. In a wet-type plasma reactor, directing a gas-phase discharge plasma toward the water film surface significantly enhanced the liquid-phase oxidation of HSO{sub 3}{sup −} to SO{sub 4}{sup 2−}. Comparisons of various absorbents revealed that the hydroxyl radical is a key factor in plasma-induced liquid-phase reactions. The resistivity, size distribution, and cohesive force of fly ash at different water vapor contents were measured using a Bahco centrifuge, which is a dust electrical resistivity test instrument, as well as a cohesive force test apparatus developed by the researchers. When water vapor content increased by 5%, fly ash resistivity in flue gas decreased by approximately two orders of magnitude, adhesive force and size increased, and specific surface area decreased. Therefore, ESP efficiency increased.

  13. Studies of gas phase ion/molecule reactions by Fourier transform ion cyclotron resonance mass spectrometry

    International Nuclear Information System (INIS)

    Kleingeld, J.C.

    1984-01-01

    An important field in which Fourier-transform ion cyclotron resonance has useful applications is that of gas phase ion chemistry, the subject of this thesis. First, the general picture of ion-molecule reactions in the gas phase is discussed. Next, some positive ion-molecule reactions are described, whereas the remaining chapters deal with negative ion-molecule reactions. Most of these studies have been performed using the FT-ICR method. Reactions involving H 3 O - and NH 4 - ions are described whereas the other chapters deal with larger organic complexes. (Auth.)

  14. Transport and reaction processes affecting the attenuation of landfill gas in cover soils

    DEFF Research Database (Denmark)

    Molins, S.; Mayer, K.U.; Scheutz, Charlotte

    2008-01-01

    of methane, chlorofluorocarbons, and hydrochlorofluorocarbons to the atmosphere. This study was conducted to investigate the effect of oxidation reactions on the overall gas transport regime and to evaluate, the contributions of various gas transport processes on methane attenuation in landfill cover soils....... For this purpose, a reactive transport model that includes advection and the Dusty Gas Model for simulation of multicomponent gas diffusion was used. The simulations are constrained by data from a series of counter-gradient laboratory experiments. Diffusion typically accounts for over 99% of methane emission...... to the atmosphere. Oxygen supply into the soil column is driven exclusively by diffusion, whereas advection outward offsets part of the diffusive contribution. In the reaction zone, methane consumption reduces the pressure gradient, further decreasing the significance of advection near the top of the column...

  15. Water Use for Unconventional Energy Development: How Much, What Kind, and to What Reaction?

    Science.gov (United States)

    Grubert, E.

    2017-12-01

    Water resources—access to water, protection of water, and allocation of water in particular—are a major priority for Americans, but water use for the energy sector has not previously been well characterized. Water use and management associated with unconventional energy development is of special interest, in part because it is often new to the locations and contexts where it occurs. This presentation focuses on three major questions about water use for unconventional energy development, drawing on both engineering and anthropological research. First, using results from a recent study of water use for energy in the entire United States, how much water does the US use for unconventional energy resources, and how does that compare with water use for more mature fuel cycles? Second, based on that same study, what kind of water is used for these unconventional energy resource fuel cycles? Specifically, where does the water come from, and what is its quality? Finally, drawing on recent case studies in the US and elsewhere, what has the reaction been to these water uses, and why does that matter? Case studies focused on oil and natural gas resources illustrate societal reactions to issues of both water management, particularly related to induced seismicity associated with produced water injection, and water allocation, particularly related to hydraulic fracturing. Overall, recent work finds that public concern about water used for unconventional energy resources is often better explained by observed or anticipated local impacts and the uncertainty surrounding these impacts than by specifics about quantities, allocation, and management techniques. This work provides both quantitative and qualitative characterization of water management and allocation for unconventional energy development.

  16. Thin liquid films with time-dependent chemical reactions sheared by an ambient gas flow

    Science.gov (United States)

    Bender, Achim; Stephan, Peter; Gambaryan-Roisman, Tatiana

    2017-08-01

    Chemical reactions in thin liquid films are found in many industrial applications, e.g., in combustion chambers of internal combustion engines where a fuel film can develop on pistons or cylinder walls. The reactions within the film and the turbulent outer gas flow influence film stability and lead to film breakup, which in turn can lead to deposit formation. In this work we examine the evolution and stability of a thin liquid film in the presence of a first-order chemical reaction and under the influence of a turbulent gas flow. Long-wave theory with a double perturbation analysis is used to reduce the complexity of the problem and obtain an evolution equation for the film thickness. The chemical reaction is assumed to be slow compared to film evolution and the amount of reactant in the film is limited, which means that the reaction rate decreases with time as the reactant is consumed. A linear stability analysis is performed to identify the influence of reaction parameters, material properties, and environmental conditions on the film stability limits. Results indicate that exothermic reactions have a stabilizing effect whereas endothermic reactions destabilize the film and can lead to rupture. It is shown that an initially unstable film can become stable with time as the reaction rate decreases. The shearing of the film by the external gas flow leads to the appearance of traveling waves. The shear stress magnitude has a nonmonotonic influence on film stability.

  17. Modeling and analysis of liquid deuterium-water reactions

    International Nuclear Information System (INIS)

    Taleyarkhan, R.P.

    1995-01-01

    This Presentation highlights the following: Overview of LD 2 -water reactions their connections to research reactors with cold sources; some key features and ingredients of vapor explosions in general; Examination of results of 1970 experiment at Grenoble Nuclear Research Center; Thermodynamic evaluations of energetics of explosive LD 2 -D 2 O reactions. This presentation concentrates only on the technical aspects of LD 2 /LH 2 - water reactions; it is not intended to draw/imply safety-related conclusions for research reactors

  18. Gas-driven pump for ground-water samples

    Science.gov (United States)

    Signor, Donald C.

    1978-01-01

    Observation wells installed for artificial-recharge research and other wells used in different ground-water programs are frequently cased with small-diameter steel pipe. To obtain samples from these small-diameter wells in order to monitor water quality, and to calibrate solute-transport models, a small-diameter pump with unique operating characteristics is required that causes a minimum alternation of samples during field sampling. A small-diameter gas-driven pump was designed and built to obtain water samples from wells of two-inch diameter or larger. The pump is a double-piston type with the following characteristics: (1) The water sample is isolated from the operating gas, (2) no source of electricity is ncessary, (3) operation is continuous, (4) use of compressed gas is efficient, and (5) operation is reliable over extended periods of time. Principles of operation, actual operation techniques, gas-use analyses and operating experience are described. Complete working drawings and a component list are included. Recent modifications and pump construction for high-pressure applications also are described. (Woodard-USGS)

  19. Gas-phase thermolysis reaction of formaldehyde diperoxide. Kinetic study and theoretical mechanisms

    International Nuclear Information System (INIS)

    Jorge, Nelly Lidia; Romero, Jorge Marcelo; Grand, André; Hernández-Laguna, Alfonso

    2012-01-01

    Highlights: ► Kinetic and mechanism of the gas-phase thermolysis of tetroxane were determined. ► Gas chromatography and computational potential energy surfaces were performed. ► A mechanism in steps looked like the most probable mechanism. ► A spin–orbit coupling appeared at the singlet and triple diradical open structures. ► A non-adiabatic crossing from the singlet to the triplet state occurred. - Abstract: Gas-phase thermolysis reaction of formaldehyde diperoxide (1,2,4,5-tetroxane) was performed in an injection chamber of a gas chromatograph at a range of 463–503 K. The average Arrhenius activation energy and pre-exponential factor were 29.3 ± 0.8 kcal/mol and 5.2 × 10 13 s −1 , respectively. Critical points and reaction paths of the ground singlet and first triplet potential energy surfaces (PES) were calculated, using DFT method at BHANDHLYP/6-311+G ∗∗ level of the theory. Also, G3 calculations were performed on the reactant and products. Reaction by the ground-singlet and first-triplet states turned out to be endothermic and exothermic, respectively. The mechanism in three steps seemed to be the most probable one. An electronically non-adiabatic process appeared, in which a crossing, at an open diradical structure, from the singlet to the triplet state PES occurred, due to a spin–orbit coupling, yielding an exothermic reaction. Theoretical kinetic constant coming from the non- adiabatic transition from the singlet to the triplet state agrees with the experimental values.

  20. Experimental study of the role of nanoparticles in sodium–water reaction

    International Nuclear Information System (INIS)

    Park, Gunyeop; Kim, Soo Jae; Kim, Moo Hwan; Park, Hyun Sun

    2014-01-01

    Highlights: • We experimentally research the effect of nanoparticles in sodium–water reaction. • We present sodium–water reaction experiments and observed the mitigated reaction rate of sodium nanofluid. • We indicate nanoparticles settled on the surface of liquid sodium affect to mitigate chemical reactivity of sodium during sodium–water reaction. - Abstract: This paper presents an experimental study of the effect of Titanium (Ti) nanoparticles (NPs) on the mechanism of Sodium–Water chemical Reaction (SWR). Sodium–Titanium Nano Fluid (NaTiNF), i.e., liquid sodium that includes dispersed Ti NPs (≤100 nm) at 0.214 vol.% was produced. To simulate an accident in a sodium–water heat exchanger in a Sodium-cooled Fast Reactor, SWR was conducted by injecting liquid water directly onto the surface of liquid sodium. The reaction behavior of NaTiNF was quantitatively compared with that of bare sodium. Experiment results present that NaTiNF shows mitigated reactivity with water and lower reaction rate than bare sodium. These results imply that NPs dispersed in liquid sodium affect the mechanism of SWR

  1. Gas-Solid Reaction Properties of Fluorine Compounds and Solid Adsorbents for Off-Gas Treatment from Semiconductor Facility

    Directory of Open Access Journals (Sweden)

    Shinji Yasui

    2012-01-01

    Full Text Available We have been developing a new dry-type off-gas treatment system for recycling fluorine from perfluoro compounds present in off-gases from the semiconductor industry. The feature of this system is to adsorb the fluorine compounds in the exhaust gases from the decomposition furnace by using two types of solid adsorbents: the calcium carbonate in the upper layer adsorbs HF and converts it to CaF2, and the sodium bicarbonate in the lower layer adsorbs HF and SiF4 and converts them to Na2SiF6. This paper describes the fluorine compound adsorption properties of both the solid adsorbents—calcium carbonate and the sodium compound—for the optimal design of the fixation furnace. An analysis of the gas-solid reaction rate was performed from the experimental results of the breakthrough curve by using a fixed-bed reaction model, and the reaction rate constants and adsorption capacity were obtained for achieving an optimal process design.

  2. Production of H2 from aluminium/water reaction and its potential for CO2 methanation

    Science.gov (United States)

    Khai Phung, Khor; Sethupathi, Sumathi; Siang Piao, Chai

    2018-04-01

    Carbon dioxide (CO2) is a natural gas that presents in excess in the atmosphere. Owing to its ability to cause global warming, capturing and conversion of CO2 have attracted much attention worldwide. CO2 methanation using hydrogen (H2) is believed to be a promising route for CO2 removal. In the present work, H2 is produced using aluminum-water reaction and tested for its ability to convert CO2 to methane (CH4). Different type of water i.e. tap water, distilled water, deionized water and ultrapure water, concentration of sodium hydroxide (NaOH) (0.2 M to 1.0 M) and particle size of aluminum (45 m to 500 μm) were varied as parameter study. It was found that the highest yield of H2 was obtained using distilled water, 1.0 M of NaOH and 45μm particle size of aluminium. However, the highest yield of methane was achieved using a moderate and progressive H2 production (distilled water, 0.6 M of NaOH and 45 μm particle size of aluminium) which allowed sufficient time for H2 to react with CO2. It was concluded that 1130 ml of H2 can produce about 560 ppm of CH4 within 25 min of batch reaction using nickel catalyst.

  3. Hydrogen production from high-moisture content biomass in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Antal, M.J. Jr.; Adschiri, T.; Ekbom, T. [Univ. of Hawaii, Honolulu, HI (United States)] [and others

    1996-10-01

    Most hydrogen is produced by steam reforming methane at elevated pressures. The goal of this research is to develop commercial processes for the catalytic steam reforming of biomass and other organic wastes at high pressures. This approach avoids the high cost of gas compression and takes advantage of the unique properties of water at high pressures. Prior to this year the authors reported the ability of carbon to catalyze the decomposition of biomass and related model compounds in supercritical water. The product gas consists of hydrogen, carbon dioxide, carbon monoxide, methane, and traces of higher hydrocarbons. During the past year the authors have: (a) developed a method to extend the catalyst life, (b) begun studies of the role of the shift reaction, (c) completed studies of carbon dioxide absorption from the product effluent by high pressure water, (d) measured the rate of carbon catalyst gasification in supercritical water, (e) discovered the pumpability of oil-biomass slurries, and (f) completed the design and begun fabrication of a flow reactor that will steam reform whole biomass feedstocks (i.e. sewage sludge) and produce a hydrogen rich synthesis gas at very high pressure (>22 MPa).

  4. Uranium reactions with water vapor. Final progress report

    International Nuclear Information System (INIS)

    Condon, J.B.; Cristy, S.S.; Kirkpatrick, J.R.

    1983-01-01

    The reaction kinetics and ion microprobe mass analyzer (IMMA) depth-profile data for water-oxygen-uranium reaction is explained in terms of the perfusive-precipitation model. This model is reviewed extensively enough to deal with this interacting, 3-element reaction system. The model, based on simultaneous diffusion and product precipitation, can be applied to several systems in a parameterless fashion. It is applied to the uranium-water reaction in the absence and presence of the oxygen inhibitor. The results of the calculations of the model are compared to the experimental rates and the IMMA depth profiles obtained when 18 O-labeled water is used. The predictions are excellent for the pressure dependence of the rates, the activation energies for both the oxygen-poisoned and oxygen-free reactions, the absolute rates for the oxygen-poisoned case, and the IMMA depth profiles. The prediction of the absolute rate for the oxygen-free case is only within a factor of five due to the approximations made for the thermodynamics of the product layer that fixes the oxygen activity. Comparison of the model to experimental data for other metal-oxidation systems such as iron, silicon, copper, zirconium with oxygen, and thorium with water, is also presented to lend credibility to the modeling technique

  5. Hydrogen production via thermochemical water-splitting by lithium redox reaction

    International Nuclear Information System (INIS)

    Nakamura, Naoya; Miyaoka, Hiroki; Ichikawa, Takayuki; Kojima, Yoshitsugu

    2013-01-01

    Highlights: •Hydrogen production via water-splitting by lithium redox reactions possibly proceeds below 800 °C. •Entropy control by using nonequilibrium technique successfully reduces the reaction temperature. •The operating temperature should be further reduced by optimizing the nonequilibrium condition to control the cycle. -- Abstracts: Hydrogen production via thermochemical water-splitting by lithium redox reactions was investigated as energy conversion technique. The reaction system consists of three reactions, which are hydrogen generation by the reaction of lithium and lithium hydroxide, metal separation by thermolysis of lithium oxide, and oxygen generation by hydrolysis of lithium peroxide. The hydrogen generation reaction completed at 500 °C. The metal separation reaction is thermodynamically difficult because it requires about 3400 °C in equilibrium condition. However, it was indicated from experimental results that the reaction temperature was drastically reduced to 800 °C by using nonequilibrium technique. The hydrolysis reaction was exothermic reaction, and completed by heating up to 300 °C. Therefore, it was expected that the water-splitting by lithium redox reactions was possibly operated below 800 °C under nonequilibrium condition

  6. Combined steam and carbon dioxide reforming of methane and side reactions: Thermodynamic equilibrium analysis and experimental application

    International Nuclear Information System (INIS)

    Jang, Won-Jun; Jeong, Dae-Woon; Shim, Jae-Oh; Kim, Hak-Min; Roh, Hyun-Seog; Son, In Hyuk; Lee, Seung Jae

    2016-01-01

    Highlights: • Selected variables have a significant influence on yields of synthesis gas. • (CO_2 + H_2O)/CH_4 affects the temperature which can achieve the maximum conversion. • Coke is formed at low temperatures even with excess oxidizing agent. • The occurrence of RWGS becomes critical in real chemical reactions. • Equilibrium conversions are maintained for 500 h without detectable deactivation. - Abstract: Thermodynamic equilibrium analysis of the combined steam and carbon dioxide reforming of methane (CSCRM) and side reactions was performed using total Gibbs free energy minimization. The effects of (CO_2 + H_2O)/CH_4 ratio (0.9–2.9), CO_2:H_2O ratio (3:1–1:3), and temperature (500–1000 °C) on the equilibrium conversions, yields, coke yield, and H_2/CO ratio were investigated. A (CO_2 + H_2O)/CH_4 ratio greater than 1.2, a CO_2:H_2O ratio of 1:2.1, and a temperature of at least 850 °C are preferable reaction conditions for the synthesis gas preparation in the gas to liquid process. Simulated conditions were applied to the CSCRM reaction and the experimental data were compared with the thermodynamic equilibrium results. The thermodynamic equilibrium results were mostly consistent with the experimental data, but the reverse water gas shift reaction rapidly occurred in the real chemical reaction and under excess oxidizing agent conditions. In addition, a long-term stability test (under simulated conditions) showed that the equilibrium conversion was maintained for 500 h and that the coke formation on the used catalyst was not observed.

  7. Theoretical investigation of the hydrogen shift reactions in peroxy radicals derived from the atmospheric decomposition of 3-methyl-3-buten-1-ol (MBO331)

    DEFF Research Database (Denmark)

    Knap, Hasse Christian; Jørgensen, Solvejg; Kjærgaard, Henrik Grum

    2015-01-01

    The hydroxy peroxy radical derived from the oxidation of 3-methyl-3-buten-1-ol (MBO331), can undergo four different hydrogen shift (H-shift) reactions. We have compared optimized geometries, barrier heights and reaction rate constants obtained with five different DFT functionals (BLYP, B3LYP, BHand...

  8. Effects of gas flow on oxidation reaction in liquid induced by He/O{sub 2} plasma-jet irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Atsushi; Uchida, Giichiro, E-mail: uchida@jwri.osaka-u.ac.jp; Takenaka, Kosuke; Setsuhara, Yuichi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Kawasaki, Toshiyuki [Department of Mechanical and Electrical Engineering, Nippon Bunri University, Oita, Oita 870-0397 (Japan); Koga, Kazunori; Sarinont, Thapanut; Amano, Takaaki; Shiratani, Masaharu [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Fukuoka 819-0395 (Japan)

    2015-07-28

    We present here analysis of oxidation reaction in liquid by a plasma-jet irradiation under various gas flow patterns such as laminar and turbulence flows. To estimate the total amount of oxidation reaction induced by reactive oxygen species (ROS) in liquid, we employ a KI-starch solution system, where the absorbance of the KI-starch solution near 600 nm behaves linear to the total amount of oxidation reaction in liquid. The laminar flow with higher gas velocity induces an increase in the ROS distribution area on the liquid surface, which results in a large amount of oxidation reaction in liquid. However, a much faster gas flow conversely results in a reduction in the total amount of oxidation reaction in liquid under the following two conditions: first condition is that the turbulence flow is triggered in a gas flow channel at a high Reynolds number of gas flow, which leads to a marked change of the spatial distribution of the ROS concentration in gas phase. Second condition is that the dimpled liquid surface is formed by strong gas flow, which prevents the ROS from being transported in radial direction along the liquid surface.

  9. Reaction rate constant for uranium in water and water vapor

    Energy Technology Data Exchange (ETDEWEB)

    TRIMBLE, D.J.

    1998-11-09

    The literature on uranium oxidation in water and oxygen free water vapor was reviewed. Arrhenius rate equations were developed from the review data. These data and equations will be used as a baseline from which to compare reaction rates measured for K Basin fuel.

  10. Helium Isotopes and Noble Gas Abundances of Cave Dripping Water in Three Caves in East Asia

    Science.gov (United States)

    Chen, A. T.; Shen, C. C.; Tan, M.; Li, T.; Uemura, R.; Asami, R.

    2015-12-01

    Paleo-temperature recorded in nature archives is a critical parameter to understand climate change in the past. With advantages of unique inert chemical characteristics and sensitive solubilities with temperature, dissolved noble gases in speleothem inclusion water were recently proposed to retrieve terrestrial temperature history. In order to accurately apply this newly-developed speleothem noble gas temperature (NGT) as a reliable proxy, a fundamental issue about behaviors of noble gases in the karst should be first clarified. In this study, we measured noble gas contents in air and dripping water to evaluate any ratio deviation between noble gases. Cave dripping water samples was collected from three selected caves, Shihua Cave in northern China, Furong Cave in southwestern, and Gyukusen Cave in an island located in the western Pacific. For these caves are characterized by a thorough mixing and long-term storage of waters in a karst aquifer by the absence of seasonal oxygen isotope shifts. Ratios of dripping water noble gases are statistically insignificant from air data. Helium isotopic ratios in the dripping water samples match air value. The results indicate that elemental and isotopic signatures of noble gases from air can be frankly preserved in the epikarst and support the fidelity of NGT techniques.

  11. Radiation-use efficiency and gas exchange responses to water and nutrient availability in irrigated and fertilized stands of sweetgum and sycamore

    Science.gov (United States)

    Christopher B. Allen; Rodney E. Will; Robert C. McGravey; David R. Coyle; Mark D. Coleman

    2005-01-01

    We investigated how water and nutrient availability affect radiation-use effeciency (e) and assessed leaf gas exchange as a possible mechanism for shifts in e. We measured aboveground net primary production (ANPP) and annual photosynthetically active radiation (PAR) capture to calculate e as well as leaf-level physiological variables (light-saturated net photosynthesis...

  12. Gas-Chromatographic Determination Of Water In Freon PCA

    Science.gov (United States)

    Melton, Donald M.

    1994-01-01

    Gas-chromatographic apparatus measures small concentrations of water in specimens of Freon PCA. Testing by use of apparatus faster and provides greater protection against accidental contamination of specimens by water in testing environment. Automated for unattended operation. Also used to measure water contents of materials, other than Freon PCA. Innovation extended to development of purgeable sampling accessory for gas chromatographs.

  13. The behaviour of radionuclides in gas adsorption chromatographic processes with superimposed chemical reactions (chlorides)

    International Nuclear Information System (INIS)

    Eichler, B.

    1996-01-01

    Thermochemical relationships are derived describing the gas adsorption chromatographic transport of carrier-free radionuclides. Especially, complex adsorption processes such as dissociative, associative and substitutive adsorption are dealt with. The comparison of experimental with calculated data allows the determination of the type of adsorption reaction, which is the basis of the respective gas chromatographic process. The behaviour of carrier-free radionuclides of elements Pu, Ce, Ru, Co and Cr in thermochromatographic experiments with chlorinating carrier gases can be described as dissociative adsorption of chlorides in higher oxidation states. The gas adsorption chromatographic transport of Zr with oxygen and chlorine containing carrier gas is shown to be a substitutive adsorption process. The consequences of superimposed chemical reactions on the interpretation of results and the conception of gas adsorption chromatographic experiments with carrier-free radionuclides in isothermal columns and in temperature gradient tubes is discussed. (orig.)

  14. Impact of Shale Gas Development on Water Resource in Fuling, China

    Science.gov (United States)

    Yang, Hong; Huang, Xianjin; Yang, Qinyuan; Tu, Jianjun

    2015-04-01

    As a low-carbon energy, shale gas rapidly developed in U.S. in last years due to the innovation of the technique of hydraulic fracture, or fracking. Shale gas boom produces more gas with low price and reduced the reliance on fuel import. To follow the American shale gas success, China made an ambitious plan of shale gas extraction, 6.5 billion m3 by 2015. To extract shale gas, huge amount water is needed to inject into each gas well. This will intensify the competition of water use between industry, agricultural and domestic sectors. It may finally exacerbate the water scarcity in China. After the extraction, some water was returned to the ground. Without adequate treatment, the flowback water can introduce heavy metal, acids, pesticides, and other toxic material into water and land. This may inevitably worsen the water and land contamination. This study analysed the potential water consumption and wastewater generation in shale gas development in Fuling, Southwest China. The survey found the average water consumption is 30,000 cubic meter for one well, higher than shale well in U.S. Some 2%-20% water flowed back to the ground. The water quality monitoring showed the Total Suspended Solid (TSS) and Chemical Oxygen Demand (COD) were the main factors above those specified by China's water regulation. Shale gas is a lower-carbon energy, but it is important to recognize the water consuming and environmental pollution during the fracking. Strict monitoring and good coordination during the shale gas exploitation is urgently needed for the balance of economic development, energy demand and environmental protection.

  15. Non-stationary filtration mode during chemical reactions with the gas phase

    Science.gov (United States)

    Zavialov, Ivan; Konyukhov, Andrey; Negodyaev, Sergey

    2015-04-01

    An experimental and numerical study of filtration accompanied by chemical reactions between displacing fluid and solid skeleton is considered. Glass balls (400-500 μm in diameter) were placed in 1 cm gap between two glass sheets and were used as model porous medium. The baking soda was added to the glass balls. The 70% solution of acetic acid was used as the displacer. The modeling porous medium was saturated with a mineral oil, and then 70% solution of colored acetic acid was pumped through the medium. The glass balls and a mineral oil have a similar refractive index, so the model porous medium was optically transparent. During the filtration, the gas phase was generated by the chemical reactions between the baking soda and acetic acid, and time-dependent displacement of the chemical reaction front was observed. The front of the chemical reaction was associated with the most intensive gas separation. The front moved, stopped, and then moved again to the area where it had been already. We called this process a secondary oxidation wave. To describe this effect, we added to the balance equations a term associated with the formation and disappearance of phases due to chemical reactions. The equations were supplemented by Darcy's law for multiphase filtration. Nonstationarity front propagation of the chemical reaction in the numerical experiment was observed at Damköhler numbers greater than 100. The mathematical modelling was agreed well with the experimental results.

  16. Gas-phase thermolysis reaction of formaldehyde diperoxide. Kinetic study and theoretical mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Jorge, Nelly Lidia [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Av. Las Palmeras 4, 18100 Armilla, Granada (Spain); Area de Quimica Fisica Facultad de Ciencias Exactas y Naturales y Agrimensura, UNNE, Avda. Libertad 5460, 3400 Corrientes (Argentina); Romero, Jorge Marcelo [Area de Quimica Fisica Facultad de Ciencias Exactas y Naturales y Agrimensura, UNNE, Avda. Libertad 5460, 3400 Corrientes (Argentina); Grand, Andre [INAC, SCIB, Laboratoire ' Lesions des Acides Nucleiques' , UMR CEA-UJF E3, CEA-Grenoble, 17 Rue des Martyrs, 38054 Grenoble cedex 9 (France); Hernandez-Laguna, Alfonso, E-mail: ahlaguna@ugr.es [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Av. Las Palmeras 4, 18100 Armilla, Granada (Spain)

    2012-01-17

    Highlights: Black-Right-Pointing-Pointer Kinetic and mechanism of the gas-phase thermolysis of tetroxane were determined. Black-Right-Pointing-Pointer Gas chromatography and computational potential energy surfaces were performed. Black-Right-Pointing-Pointer A mechanism in steps looked like the most probable mechanism. Black-Right-Pointing-Pointer A spin-orbit coupling appeared at the singlet and triple diradical open structures. Black-Right-Pointing-Pointer A non-adiabatic crossing from the singlet to the triplet state occurred. - Abstract: Gas-phase thermolysis reaction of formaldehyde diperoxide (1,2,4,5-tetroxane) was performed in an injection chamber of a gas chromatograph at a range of 463-503 K. The average Arrhenius activation energy and pre-exponential factor were 29.3 {+-} 0.8 kcal/mol and 5.2 Multiplication-Sign 10{sup 13} s{sup -1}, respectively. Critical points and reaction paths of the ground singlet and first triplet potential energy surfaces (PES) were calculated, using DFT method at BHANDHLYP/6-311+G{sup Asterisk-Operator Asterisk-Operator} level of the theory. Also, G3 calculations were performed on the reactant and products. Reaction by the ground-singlet and first-triplet states turned out to be endothermic and exothermic, respectively. The mechanism in three steps seemed to be the most probable one. An electronically non-adiabatic process appeared, in which a crossing, at an open diradical structure, from the singlet to the triplet state PES occurred, due to a spin-orbit coupling, yielding an exothermic reaction. Theoretical kinetic constant coming from the non- adiabatic transition from the singlet to the triplet state agrees with the experimental values.

  17. A high-throughput headspace gas chromatographic technique for the determination of nitrite content in water samples.

    Science.gov (United States)

    Zhang, Shu-Xin; Peng, Rong; Jiang, Ran; Chai, Xin-Sheng; Barnes, Donald G

    2018-02-23

    This paper reports on a high-throughput headspace gas chromatographic method (HS-GC) for the determination of nitrite content in water sample, based on GC measurement of cyclohexene produced from the reaction between nitrite and cyclamate in a closed vial. The method has a relative standard deviation of water samples. In short, the present HS-GC method is simple, accurate, and sensitive, and it is very suitable to be used in the batch sample testing. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Water vapor and Gas Transport through Polymeric Membranes

    NARCIS (Netherlands)

    Metz, S.J.

    2003-01-01

    Water vapor transport through polymeric materials plays an important role in a large number of applications such as: food packaging, breathable clothing, roofing membranes, diapers, and the removal of water vapor from gas streams (e.g. dehydration of natural gas or the drying of compressed air).

  19. Fission gas behaviour in water reactor fuels

    International Nuclear Information System (INIS)

    2002-01-01

    During irradiation, nuclear fuel changes volume, primarily through swelling. This swelling is caused by the fission products and in particular by the volatile ones such as krypton and xenon, called fission gas. Fission gas behaviour needs to be reliably predicted in order to make better use of nuclear fuel, a factor which can help to achieve the economic competitiveness required by today's markets. These proceedings communicate the results of an international seminar which reviewed recent progress in the field of fission gas behaviour in light water reactor fuel and sought to improve the models used in computer codes predicting fission gas release. State-of-the-art knowledge is presented for both uranium-oxide and mixed-oxide fuels loaded in water reactors. (author)

  20. Shifting cultivation effects on creek water quality around Barkal Upazila in Chittagong Hill Tracts, Bangladesh

    Institute of Scientific and Technical Information of China (English)

    Shyamal Karmakar; S.M.Sirajul Haque; M.Mozaffar Hossain; Sohag Miah

    2012-01-01

    We report the effects of shifting cultivation on water quality in 16 creeks investigated once in 2007 and twice in 2008 in 16 apparently similar small neighboring watersheds,each of 3 to 5 ha,at four locations around Barkal sub-district under Rangamati District of Chittagong Hill Tracts in Bangladesh.Concentrations of SO42-and K+,and pH in creek water were lower,and NO3-N and Na+ concentrations were higher in shifting-cultivation land compared to land with either plantation or natural forest or a combination of these cover types.Shifting cultivation effects on some water quality parameters were not significant due to change in land cover of the watershed between two sampling periods either through introduction of planted tree species or naturally regenerated vegetation.Conductivity and concentrations of HCO3-.PO43-,Ca2+ and Mg2+ in creek water showed no definite trend between shifting cultivation and the other land cover types.At one area near the Forest Range Office of Barkal,creek water pH was 5.8 under land cover with a combination of shifting cultivation and plantation.At this area Na+ concentration in shifting-cultivation land ranged from 32.33 to 33.00 mg·L-1 and in vegetated area from 25.00 to 30.50 mg·L-1 in 2007.At another area,Chaliatali Chara,SO42-concentration in a shifting-cultivation watershed ranged from 4.46 to 10.51 mg·L-1,lower than in a vegetated watershed that ranged from 11.69 to 19.98 mg·L-1 in 2007.SO42-concentration in this shifting-cultivation area ranged from 1.28 to 1.37 mg·L-1 and in the vegetated area from 1.37 to 3.50 mg·L-1 in 2008.

  1. 40 CFR 1065.645 - Amount of water in an ideal gas.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Amount of water in an ideal gas. 1065... in an ideal gas. This section describes how to determine the amount of water in an ideal gas, which... of water in an ideal gas, x H20, as follows: ER30AP10.034 Where: x H20 = amount of water in an ideal...

  2. Process for water-gas generation from degassed combustibles

    Energy Technology Data Exchange (ETDEWEB)

    1906-05-23

    A process for water-gas generation in a continuous operation from degassed combustibles in the lower part of a vertical exterior-heated retort, whose middle part can serve to degas the combustibles, is described. It is characterized in that the water vapor employed is obtained by vaporizing water in the upper part of the retort by means of the waste heat from the heating gases, which had effected the coking of the combustibles before the water-gas recovery or after the latter.

  3. On factors influencing air-water gas exchange in emergent wetlands

    Science.gov (United States)

    Ho, David T.; Engel, Victor C.; Ferron, Sara; Hickman, Benjamin; Choi, Jay; Harvey, Judson W.

    2018-01-01

    Knowledge of gas exchange in wetlands is important in order to determine fluxes of climatically and biogeochemically important trace gases and to conduct mass balances for metabolism studies. Very few studies have been conducted to quantify gas transfer velocities in wetlands, and many wind speed/gas exchange parameterizations used in oceanographic or limnological settings are inappropriate under conditions found in wetlands. Here six measurements of gas transfer velocities are made with SF6 tracer release experiments in three different years in the Everglades, a subtropical peatland with surface water flowing through emergent vegetation. The experiments were conducted under different flow conditions and with different amounts of emergent vegetation to determine the influence of wind, rain, water flow, waterside thermal convection, and vegetation on air-water gas exchange in wetlands. Measured gas transfer velocities under the different conditions ranged from 1.1 cm h−1 during baseline conditions to 3.2 cm h−1 when rain and water flow rates were high. Commonly used wind speed/gas exchange relationships would overestimate the gas transfer velocity by a factor of 1.2 to 6.8. Gas exchange due to thermal convection was relatively constant and accounted for 14 to 51% of the total measured gas exchange. Differences in rain and water flow among the different years were responsible for the variability in gas exchange, with flow accounting for 37 to 77% of the gas exchange, and rain responsible for up to 40%.

  4. Oxo-exchange of gas-phase uranyl, neptunyl, and plutonyl with water and methanol.

    Science.gov (United States)

    Lucena, Ana F; Odoh, Samuel O; Zhao, Jing; Marçalo, Joaquim; Schreckenbach, Georg; Gibson, John K

    2014-02-17

    A challenge in actinide chemistry is activation of the strong bonds in the actinyl ions, AnO2(+) and AnO2(2+), where An = U, Np, or Pu. Actinyl activation in oxo-exchange with water in solution is well established, but the exchange mechanisms are unknown. Gas-phase actinyl oxo-exchange is a means to probe these processes in detail for simple systems, which are amenable to computational modeling. Gas-phase exchange reactions of UO2(+), NpO2(+), PuO2(+), and UO2(2+) with water and methanol were studied by experiment and density functional theory (DFT); reported for the first time are experimental results for UO2(2+) and for methanol exchange, as well as exchange rate constants. Key findings are faster exchange of UO2(2+) versus UO2(+) and faster exchange with methanol versus water; faster exchange of UO2(+) versus PuO2(+) was quantified. Computed potential energy profiles (PEPs) are in accord with the observed kinetics, validating the utility of DFT to model these exchange processes. The seemingly enigmatic result of faster exchange for uranyl, which has the strongest oxo-bonds, may reflect reduced covalency in uranyl as compared with plutonyl.

  5. Some problems on materials tests in high temperature hydrogen base gas mixture

    International Nuclear Information System (INIS)

    Shikama, Tatsuo; Tanabe, Tatsuhiko; Fujitsuka, Masakazu; Yoshida, Heitaro; Watanabe, Ryoji

    1980-01-01

    Some problems have been examined on materials tests (creep rupture tests and corrosion tests) in high temperature mixture gas of hydrogen (80%H 2 + 15%CO + 5%CO 2 ) simulating the reducing gas for direct steel making. H 2 , CO, CO 2 and CH 4 in the reducing gas interact with each other at elevated temperature and produce water vapor (H 2 O) and carbon (soot). Carbon deposited on the walls of retorts and the water condensed at pipings of the lower temperature gas outlet causes blocking of gas flow. The gas reactions have been found to be catalyzed by the retort walls, and appropriate selection of the materials for retorts has been found to mitigate the problems caused by water condensation and carbon deposition. Quartz has been recognized to be one of the most promising materials for minimizing the gas reactions. And ceramic coating, namely, BN (born nitride) on the heat resistant superalloy, MO-RE II, has reduced the amounts of water vapor and deposited carbon (sooting) produced by gas reactions and has kept dew points of outlet gas below room temperature. The well known emf (thermo-electromotive force) deterioration of Alumel-Chromel thermocouples in the reducing gases at elevated temperatures has been also found to be prevented by the ceramic (BN) coating. (author)

  6. Adiabatic flame temperature of sodium combustion and sodium-water reaction

    International Nuclear Information System (INIS)

    Okano, Y.; Yamaguchi, A.

    2001-01-01

    In this paper, background information of sodium fire and sodium-water reaction accidents of LMFBR (liquid metal fast breeder reactor) is mentioned at first. Next, numerical analysis method of GENESYS is described in detail. Next, adiabatic flame temperature and composition of sodium combustion are analyzed, and affect of reactant composition, such oxygen and moisture, is discussed. Finally, adiabatic reaction zone temperature and composition of sodium-water reaction are calculated, and affects of reactant composition, sodium vaporization, and pressure are stated. Chemical equilibrium calculation program for generic chemical system (GENESYS) is developed in this study for the research on adiabatic flame temperature of sodium combustion and adiabatic reaction zone temperature of sodium-water reaction. The maximum flame temperature of the sodium combustion is 1,950 K at the standard atmospheric condition, and is not affected by the existence of moisture. The main reaction product is Na 2 O (l) , and in combustion in moist air, with NaOH (g) . The maximum reaction zone temperature of the sodium-water reaction is 1,600 K, and increases with the system pressure. The main products are NaOH (g) , NaOH (l) and H2 (g) . Sodium evaporation should be considered in the cases of sodium-rich and high pressure above 10 bar

  7. Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction.

    Science.gov (United States)

    Jackson, Robert B; Vengosh, Avner; Darrah, Thomas H; Warner, Nathaniel R; Down, Adrian; Poreda, Robert J; Osborn, Stephen G; Zhao, Kaiguang; Karr, Jonathan D

    2013-07-09

    Horizontal drilling and hydraulic fracturing are transforming energy production, but their potential environmental effects remain controversial. We analyzed 141 drinking water wells across the Appalachian Plateaus physiographic province of northeastern Pennsylvania, examining natural gas concentrations and isotopic signatures with proximity to shale gas wells. Methane was detected in 82% of drinking water samples, with average concentrations six times higher for homes gas wells (P = 0.0006). Ethane was 23 times higher in homes gas wells (P = 0.0013); propane was detected in 10 water wells, all within approximately 1 km distance (P = 0.01). Of three factors previously proposed to influence gas concentrations in shallow groundwater (distances to gas wells, valley bottoms, and the Appalachian Structural Front, a proxy for tectonic deformation), distance to gas wells was highly significant for methane concentrations (P = 0.007; multiple regression), whereas distances to valley bottoms and the Appalachian Structural Front were not significant (P = 0.27 and P = 0.11, respectively). Distance to gas wells was also the most significant factor for Pearson and Spearman correlation analyses (P gas wells was the only statistically significant factor (P gas (4)He to CH4 in groundwater were characteristic of a thermally postmature Marcellus-like source in some cases. Overall, our data suggest that some homeowners living gas wells have drinking water contaminated with stray gases.

  8. Configuration of a pulse radiolysis system for the study of gas-phase reactions and kinetic investigations of the reactions of hydroxyl radicals with methyl and ethyl radicals

    International Nuclear Information System (INIS)

    Fagerstroem, K.

    1993-01-01

    The work that is presented in this thesis deals with the assembling and testing of a pulse radiolysis system for kinetic studies of gas-phase reactions as well as with the kinetics of the gas-phase reactions of hydroxyl radicals with methyl and ethyl radicals. These radicals are very important as these are formed at an early stage in hydrocarbon combustion processes. The two studied reactions are key reactions in those processes. (6 refs., 4 figs., 2 tabs.)

  9. Lattice-enabled nuclear reactions in the nickel and hydrogen gas system

    International Nuclear Information System (INIS)

    Nagel, David J.

    2015-01-01

    Thousands of lattice-enabled nuclear reaction (LENR) experiments involving electrochemical loading of deuterium into palladium have been conducted and reported in hundreds of papers. But, it appears that the first commercial LENR power generators will employ gas loading of hydrogen onto nickel. This article reviews the scientific base for LENR in the gas-loaded Ni-H system, and some of the tests of pre-commercial prototype generators based on this combination. (author)

  10. Reaction behavior of SO2 in the sintering process with flue gas recirculation.

    Science.gov (United States)

    Yu, Zhi-Yuan; Fan, Xiao-Hui; Gan, Min; Chen, Xu-Ling; Chen, Qiang; Huang, Yun-Song

    2016-07-01

    The primary goal of this paper is to reveal the reaction behavior of SO2 in the sinter zone, combustion zone, drying-preheating zone, and over-wet zone during flue gas recirculation (FGR) technique. The results showed that SO2 retention in the sinter zone was associated with free-CaO in the form of CaSO3/CaSO4, and the SO2 adsorption reached a maximum under 900ºC. SO2 in the flue gas came almost from the combustion zone. One reaction behavior was the oxidation of sulfur in the sintering mix when the temperature was between 800 and 1000ºC; the other behavior was the decomposition of sulfite/sulfate when the temperature was over 1000ºC. However, the SO2 adsorption in the sintering bed mainly occurred in the drying-preheating zone, adsorbed by CaCO3, Ca(OH)2, and CaO. When the SO2 adsorption reaction in the drying-preheating zone reached equilibrium, the excess SO2 gas continued to migrate to the over-wet zone and was then absorbed by Ca(OH)2 and H2O. The emission rising point of SO2 moved forward in combustion zone, and the concentration of SO2 emissions significantly increased in the case of flue gas recirculation (FGR) technique. Aiming for the reuse of the sensible heat and a reduction in exhaust gas emission, the FGR technique is proposed in the iron ore sintering process. When using the FGR technique, SO2 emission in exhaust gas gets changed. In practice, the application of the FGR technique in a sinter plant should be cooperative with the flue gas desulfurization (FGD) technique. Thus, it is necessary to study the influence of the FGR technique on SO2 emissions because it will directly influence the demand and design of the FGD system.

  11. Membranes for Flue Gas Treatment - Transport behavior of water and gas in hydrophilic polymer membranes

    NARCIS (Netherlands)

    Potreck, Jens

    2009-01-01

    Fossil fuel fired power plants produce electricity and in addition to that large volume flows of flue gas, which mainly contain N2, O2, and CO2, but also large quantities of water vapor. To prevent condensation of the water vapor present in this flue gas stream, water needs to be removed before

  12. Insight into Chemistry on Cloud/Aerosol Water Surfaces.

    Science.gov (United States)

    Zhong, Jie; Kumar, Manoj; Francisco, Joseph S; Zeng, Xiao Cheng

    2018-05-15

    Cloud/aerosol water surfaces exert significant influence over atmospheric chemical processes. Atmospheric processes at the water surface are observed to follow mechanisms that are quite different from those in the gas phase. This Account summarizes our recent findings of new reaction pathways on the water surface. We have studied these surface reactions using Born-Oppenheimer molecular dynamics simulations. These studies provide useful information on the reaction time scale, the underlying mechanism of surface reactions, and the dynamic behavior of the product formed on the aqueous surface. According to these studies, the aerosol water surfaces confine the atmospheric species into a specific orientation depending on the hydrophilicity of atmospheric species or the hydrogen-bonding interactions between atmospheric species and interfacial water. As a result, atmospheric species are activated toward a particular reaction on the aerosol water surface. For example, the simplest Criegee intermediate (CH 2 OO) exhibits high reactivity toward the interfacial water and hydrogen sulfide, with the reaction times being a few picoseconds, 2-3 orders of magnitude faster than that in the gas phase. The presence of interfacial water molecules induces proton-transfer-based stepwise pathways for these reactions, which are not possible in the gas phase. The strong hydrophobicity of methyl substituents in larger Criegee intermediates (>C1), such as CH 3 CHOO and (CH 3 ) 2 COO, blocks the formation of the necessary prereaction complexes for the Criegee-water reaction to occur at the water droplet surface, which lowers their proton-transfer ability and hampers the reaction. The aerosol water surface provides a solvent medium for acids (e.g., HNO 3 and HCOOH) to participate in reactions via mechanisms that are different from those in the gas and bulk aqueous phases. For example, the anti-CH 3 CHOO-HNO 3 reaction in the gas phase follows a direct reaction between anti-CH 3 CHOO and HNO 3

  13. Modelling the radiolysis of RSG-GAS primary cooling water

    Science.gov (United States)

    Butarbutar, S. L.; Kusumastuti, R.; Subekti, M.; Sunaryo, G. R.

    2018-02-01

    Water chemistry control for light water coolant reactor required a reliable understanding of radiolysis effect in mitigating corrosion and degradation of reactor structure material. It is known that oxidator products can promote the corrosion, cracking and hydrogen pickup both in the core and in the associated piping components of the reactor. The objective of this work is to provide the radiolysis model of RSG GAS cooling water and further more to predict the oxidator concentration which can lead to corrosion of reactor material. Direct observations or measurements of the chemistry in and around the high-flux core region of a nuclear reactor are difficult due to the extreme conditions of high temperature, pressure, and mixed radiation fields. For this reason, chemical models and computer simulations of the radiolysis of water under these conditions are an important route of investigation. FACSIMILE were used to calculate the concentration of O2 formed at relatively long-time by the pure water γ and neutron irradiation (pH=7) at temperature between 25 and 50 °C. This simulation method is based on a complex chemical reaction kinetic. In this present work, 300 MeV-proton were used to mimic γ-rays radiolysis and 2 MeV fast neutrons. Concentration of O2 were calculated at 10-6 - 106 s time scale.

  14. Study of reaction between water and exhaust gases from diesel engines used in underground mining

    Energy Technology Data Exchange (ETDEWEB)

    Mazukhina, S.I.; Kalabin, G.V.; Romanov, V.S.

    1988-05-01

    A method of mathematical simulation, based on the principle of local equilibrium of the kinetic components, was proposed for formulating and solving problems related to the combustion of fuel and the treatment of exhaust gases from a diesel engine in underground workings. Results of a study of the effects of exhaust gas quantity and composition on the reaction between the gases and water are presented. It is shown that the kinetic model correlates well with the equilibrium model, adequately describes the process, and gives a reliable picture of the changes over a period of time. The proposed method can be used to study the gas emission with different fuel mixtures and liquid neutralizing agents with a view to reducing the toxicity of diesel-engine exhaust gases.

  15. New paradigm for simplified combustion modeling of energetic solids: Branched chain gas reaction

    Energy Technology Data Exchange (ETDEWEB)

    Brewster, M.Q.; Ward, M.J. [Univ. of Illinois, Urbana, IL (United States); Son, S.F. [Los Alamos National Lab., NM (United States)

    1997-09-01

    Two combustion models with simple but rational chemistry are compared: the classical high gas activation energy (E{sub g}/RT {much_gt} 1) Denison-Baum-Williams (DBW) model, and a new low gas activation energy (E{sub g}/RT {much_lt} 1) model recently proposed by Ward, Son, and Brewster (WSB). Both models make the same simplifying assumptions of constant properties, Lewis number unity, single-step, second order gas phase reaction, and single-step, zero order, high activation energy condensed phase decomposition. The only difference is in the gas reaction activation energy E{sub g} which is asymptotically large for DBW and vanishingly small for WSB. For realistic parameters the DBW model predicts a nearly constant temperature sensitivity {sigma}{sub p} and a pressure exponent n approaching 1. The WSB model predicts generally observed values of n = 0.7 to 0.9 and {sigma}{sub p}(T{sub o},P) with the generally observed variations with temperature (increasing) and pressure (decreasing). The WSB temperature profile also matches measured profiles better. Comparisons with experimental data are made using HMX as an illustrative example (for which WSB predictions for {sigma}{sub p}(T{sub o},P) are currently more accurate than even complex chemistry models). WSB has also shown good agreement with NC/NG double base propellant and HNF, suggesting that at the simplest level of combustion modeling, a vanishingly small gas activation energy is more realistic than an asymptotically large one. The authors conclude from this that the important (regression rate determining) gas reaction zone near the surface has more the character of chain branching than thermal decomposition.

  16. Kerogen-mineral reactions at raised temperatures in the presence of water

    Energy Technology Data Exchange (ETDEWEB)

    Eglinton, T I; Rowland, S J; Curtis, C D; Douglas, A G

    1986-01-01

    Kerogen has been artificially matured under hydrous pyrolysis conditions in the presence of various minerals in order to investigate the influence of the latter on the organic products. In addition to three clay minerals (montmorillonite, illite, kaolinite), calcium carbonate and limonite were also employed as inorganic substrates. Kerogen (Type II) isolated from the Kimmeridge Blackstone band was heated in the presence of water and a 20-fold excess of mineral phase at two different temperatures (280 and 330/sup 0/C) for 72 hr. Control experiments were also carried out using kerogen and water only and kerogen under anhydrous conditions. This preliminary study describes the bulk composition of the pyrolysates with detailed analyses of the aliphatic hydrocarbon distributions being provided by gas chromatography and combined gas chromatography-mass spectrometry. In the 280/sup 0/C experiments, considerably more organic-soluble pyrolysate (15% by weight of original kerogen) was produced when calcium carbonate was the inorganic phase. At 330/sup 0/C, all samples generated much greater amounts of organic-soluble products with calcium carbonate again producing a large yield (approx. 40% wt/wt). Biomarker epimerization reactions have also proceeded further in the 330/sup 0/C pyrolysate formed in the presence of calcium carbonate than with other inorganic phases. Implications of these and other observations are discussed.

  17. Conversion of forest residues to a clean gas for fuel or synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Feldmann, H.F.; Liu, K.T.; Longanbach, J.R.; Curran, L.M.; Chauhan, S.P.

    1979-01-01

    A program is described for developing a gasification system specifically for wood and other biomass materials which allows greatly increased gasifier throughputs and direct catalysis of wood. Wood ash, which is a by-product of a wood gasification plant, can be used as a gasification catalyst for wood, as it increases gasification rates and promotes the water-gas shift reaction. The high reactivity of even uncatalyzed biomass allows the potential of very high gasifier throughputs. However, the achievement of this potential requires that the gasifier operate at gas velocities higher than those attainable in conventional reactor systems. Stable and very smooth fluidization with uniform mixing and distribution of chips throughout the bed was observed on addition of an entrained sand phase to a fluidized bed of alumina and wood chips. Economc feasibility studies based on utilization of a proprietary Battelle gasification system which utilizes an entrained-phase heat carrier indicated that an intermediate-Btu gas can be produced in 1000 ton/day plants at a price competitive with liquefied natural gas and No. 2 heating oil.

  18. Effective water influx control in gas reservoir development: Problems and countermeasures

    Directory of Open Access Journals (Sweden)

    Xi Feng

    2015-03-01

    Full Text Available Because of the diversity of geological characteristics and the complexity of percolation rules, many problems are found ineffective water influx control in gas reservoir development. The problems mainly focus on how to understand water influx rules, to establish appropriate countermeasures, and to ensure the effectiveness of technical measures. It is hard to obtain a complete applicable understanding through the isolated analysis of an individual gas reservoir due to many factors such as actual gas reservoir development phase, research work, pertinence and timeliness of measures, and so on. Over the past four decades, the exploration, practicing and tracking research have been conducted on water control in gas reservoir development in the Sichuan Basin, and a series of comprehensive water control technologies were developed integrating advanced concepts, successful experiences, specific theories and mature technologies. Though the development of most water-drive gas reservoirs was significantly improved, water control effects were quite different. Based on this background, from the perspective of the early-phase requirements of water influx control, the influencing factors of a water influx activity, the dynamic analysis method of water influx performance, the optimizing strategy of a water control, and the water control experience of typical gas reservoirs, this paper analyzed the key problems of water control, evaluated the influencing factors of water control effect, explored the practical water control strategies, and proposed that it should be inappropriate to apply the previous water control technological model to actual work but the pertinence should be improved according to actual circumstances. The research results in the paper provide technical reference for the optimization of water-invasion gas reservoir development.

  19. Gas phase reactions of nitrogen oxides with olefins

    Energy Technology Data Exchange (ETDEWEB)

    Altshuller, A P; Cohen, I

    1961-01-01

    The nature of the condensation products formed in the gas phase reactions of nitrogen dioxide and nitric oxide with pentene-1, 2-methylbutene-2, and 2-methylbutadiene-1,3 was investigated. The reactants were combined at partial pressures in the range of 0.1 to 2.5 mm with the total pressure at one atmosphere. The products were determined by infrared and ultraviolet spectroscopy and colorimetry. The condensates included primary and secondary nitro compounds and alkyl nitrates. Strong hydroxyl and single bond carbon to oxygen stretching vibrations indicate the presence of either nitroalcohols or simple aliphatic alcohols formed through oxidation reactions. Carbonyl stretching frequencies observable in some of the reactions support the conclusion that a portion of the reactants disappear by oxidation rather than by nitration processes. The available results do not indicate the presence of appreciable amounts of tert.-nitro compounds, conjugated nitro-olefins, or gem-dinitro-alkanes. The reactivities of the olefins with the nitrogen oxides are in the decreasing order: 2-methyl-butadiene-1,3, 2-methylbutene-2, pentene-1. 20 references.

  20. A fundamental study on sodium-water reaction in the double pool LMFBR, (3)

    International Nuclear Information System (INIS)

    Uotani, Masaki; Kumagai, Hiromichi; Nishi, Yoshihisa; Yoshida, Kazuo

    1989-01-01

    The double pool LMFBR is an innovative reactor that Central Research Institute of Electric Power Industry proposed for the purpose of reducing the construction cost of FBRs, and it is characterized by immersing steam generators in the annular plenum formed between the primary vessel and the outer secondary vessel. Therefore, it is expected that the pressure behavior at the time of sodium-water reaction due to the breaking of heating tubes is largely different from the case of steam generators of conventional FBRs. In order to ensure the soundness of the primary vessel that containes the reactor core, it is necessary to sufficiently grasp the pressure behavior in the plenum, and this basic experiment and analysis are related to the pressure behavior due to piston motion that arises in the initial period of quasi-steady pressure. About 1/10 scale annular plenum was used, and the generation of reaction product gas was simulated by the release of nitrogen. When gas was released in the plenum, the highest pressure rise occurred in the initial period of release, and thereafter, periodic variation arose. The pressure waveform and the value of pressure rise as the results of the model analysis agreed well with the measured results. (K.I.)

  1. Methane Occurrence in a Drinking Water Aquifer Before and During Natural Gas Production from the Marcellus Shale

    Science.gov (United States)

    Saiers, J. E.; Barth-Naftilan, E.

    2017-12-01

    More than 4,000 thousand wells have punctured aquifers of Pennsylvania's northern tier to siphon natural gas from the underlying Marcellus Shale. As drilling and hydraulic fracturing ramped up a decade ago, homeowner reports of well water contamination by methane and other contaminants began to emerge. Although made infrequently compared to the number of gas wells drilled, these reports were troubling and motivated our two-year, prospective study of groundwater quality within the Marcellus Shale Play. We installed multi-level sampling wells within a bedrock aquifer of a 25 km2 area that was targeted for shale gas development. These wells were sampled on a monthly basis before, during, and after seven shale gas wells were drilled, hydraulically fractured, and placed into production. The groundwater samples, together with surface water samples collected from nearby streams, were analyzed for hydrocarbons, trace metals, major ions, and the isotopic compositions of methane, ethane, water, strontium, and dissolved inorganic carbon. With regard to methane in particular, concentrations ranged from under 0.1 to over 60 mg/L, generally increased with aquifer depth, and, at some sites, exhibited considerable temporal variability. The isotopic composition of methane and hydrocarbon ratios also spanned a large range, suggesting that methane origins are diverse and, notably, shift on the time scale of this study. We will present inferences on factors governing methane occurrence across our study area by interpreting time-series data on methane concentrations and isotopic composition in context of local hydrologic variation, companion measurements of groundwater chemistry, and the known timing of key stages of natural gas extraction.

  2. Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber

    KAUST Repository

    Shi, Xian

    2017-01-05

    Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber are numerically investigated using an 1-D unsteady, shock-capturing, compressible and reacting flow solver. Different combinations of reaction front propagation and end-gas combustion modes are observed, i.e., 1) deflagration without end-gas combustion, 2) deflagration to end-gas autoignition, 3) deflagration to end-gas detonation, 4) developing or developed detonation, occurring in the sequence of increasing initial temperatures. Effects of ignition location and chamber size are evaluated: the asymmetric ignition is found to promote the reactivity of unburnt mixture compared to ignitions at center/wall, due to additional heating from asymmetric pressure waves. End-gas combustion occurs earlier in smaller chambers, where end-gas temperature rise due to compression heating from the deflagration is faster. According to the ξ−ε regime diagram based on Zeldovich theory, modes of reaction front propagation are primarily determined by reactivity gradients introduced by initial ignition, while modes of end-gas combustion are influenced by the total amount of unburnt mixture at the time when autoignition occurs. A transient reactivity gradient method is provided and able to capture the occurrence of detonation.

  3. Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber

    KAUST Repository

    Shi, Xian; Ryu, Je Ir; Chen, Jyh-Yuan; Dibble, Robert W.

    2017-01-01

    Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber are numerically investigated using an 1-D unsteady, shock-capturing, compressible and reacting flow solver. Different combinations of reaction front propagation and end-gas combustion modes are observed, i.e., 1) deflagration without end-gas combustion, 2) deflagration to end-gas autoignition, 3) deflagration to end-gas detonation, 4) developing or developed detonation, occurring in the sequence of increasing initial temperatures. Effects of ignition location and chamber size are evaluated: the asymmetric ignition is found to promote the reactivity of unburnt mixture compared to ignitions at center/wall, due to additional heating from asymmetric pressure waves. End-gas combustion occurs earlier in smaller chambers, where end-gas temperature rise due to compression heating from the deflagration is faster. According to the ξ−ε regime diagram based on Zeldovich theory, modes of reaction front propagation are primarily determined by reactivity gradients introduced by initial ignition, while modes of end-gas combustion are influenced by the total amount of unburnt mixture at the time when autoignition occurs. A transient reactivity gradient method is provided and able to capture the occurrence of detonation.

  4. Uranium oxidation: characterization of oxides formed by reaction with water

    International Nuclear Information System (INIS)

    Fuller, E.L. Jr.; Smyrl, N.R.; Condon, J.B.; Eager, M.H.

    1983-01-01

    Three different uranium oxide samples have been characterized with respect to the different preparation techniques. Results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. 27 figures

  5. Mitigation of Hydrogen Gas Generation from the Reaction of Uranium Metal with Water in K Basin Sludge and Sludge Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

    2011-06-08

    Prior laboratory testing identified sodium nitrate and nitrite to be the most promising agents to minimize hydrogen generation from uranium metal aqueous corrosion in Hanford Site K Basin sludge. Of the two, nitrate was determined to be better because of higher chemical capacity, lower toxicity, more reliable efficacy, and fewer side reactions than nitrite. The present lab tests were run to determine if nitrate’s beneficial effects to lower H2 generation in simulated and genuine sludge continued for simulated sludge mixed with agents to immobilize water to help meet the Waste Isolation Pilot Plant (WIPP) waste acceptance drainable liquid criterion. Tests were run at ~60°C, 80°C, and 95°C using near spherical high-purity uranium metal beads and simulated sludge to emulate uranium-rich KW containerized sludge currently residing in engineered containers KW-210 and KW-220. Immobilization agents tested were Portland cement (PC), a commercial blend of PC with sepiolite clay (Aquaset II H), granulated sepiolite clay (Aquaset II G), and sepiolite clay powder (Aquaset II). In all cases except tests with Aquaset II G, the simulated sludge was mixed intimately with the immobilization agent before testing commenced. For the granulated Aquaset II G clay was added to the top of the settled sludge/solution mixture according to manufacturer application directions. The gas volumes and compositions, uranium metal corrosion mass losses, and nitrite, ammonia, and hydroxide concentrations in the interstitial solutions were measured. Uranium metal corrosion rates were compared with rates forecast from the known uranium metal anoxic water corrosion rate law. The ratios of the forecast to the observed rates were calculated to find the corrosion rate attenuation factors. Hydrogen quantities also were measured and compared with quantities expected based on non-attenuated H2 generation at the full forecast anoxic corrosion rate to arrive at H2 attenuation factors. The uranium metal

  6. Mitigation of Hydrogen Gas Generation from the Reaction of Uranium Metal with Water in K Basin Sludge and Sludge Waste Forms

    International Nuclear Information System (INIS)

    Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

    2011-01-01

    Prior laboratory testing identified sodium nitrate and nitrite to be the most promising agents to minimize hydrogen generation from uranium metal aqueous corrosion in Hanford Site K Basin sludge. Of the two, nitrate was determined to be better because of higher chemical capacity, lower toxicity, more reliable efficacy, and fewer side reactions than nitrite. The present lab tests were run to determine if nitrate's beneficial effects to lower H2 generation in simulated and genuine sludge continued for simulated sludge mixed with agents to immobilize water to help meet the Waste Isolation Pilot Plant (WIPP) waste acceptance drainable liquid criterion. Tests were run at ∼60 C, 80 C, and 95 C using near spherical high-purity uranium metal beads and simulated sludge to emulate uranium-rich KW containerized sludge currently residing in engineered containers KW-210 and KW-220. Immobilization agents tested were Portland cement (PC), a commercial blend of PC with sepiolite clay (Aquaset II H), granulated sepiolite clay (Aquaset II G), and sepiolite clay powder (Aquaset II). In all cases except tests with Aquaset II G, the simulated sludge was mixed intimately with the immobilization agent before testing commenced. For the granulated Aquaset II G clay was added to the top of the settled sludge/solution mixture according to manufacturer application directions. The gas volumes and compositions, uranium metal corrosion mass losses, and nitrite, ammonia, and hydroxide concentrations in the interstitial solutions were measured. Uranium metal corrosion rates were compared with rates forecast from the known uranium metal anoxic water corrosion rate law. The ratios of the forecast to the observed rates were calculated to find the corrosion rate attenuation factors. Hydrogen quantities also were measured and compared with quantities expected based on non-attenuated H2 generation at the full forecast anoxic corrosion rate to arrive at H2 attenuation factors. The uranium metal

  7. Biological upgrading of coal-derived synthesis gas: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Barik, S.; Johnson, E.R.; Ko, C.W.; Clausen, E.C.; Gaddy, J.L.

    1986-10-01

    The technical feasibility of the biological conversion of coal synthesis gas to methane has been demonstrated in the University of Arkansas laboratories. Cultures of microorganisms have been developed which achieve total conversion in the water gas shift and methanation reactions in either mixed or pure cultures. These cultures carry out these conversions at ordinary temperatures and pressures, without sulfur toxicity. Several microorganisms have been identified as having commercial potential for producing methane. These include a mixed culture of unidentified bacteria; P. productus which produces acetate, a methane precursor; and Methanothrix sp., which produces methane from acetate. These cultures have been used in mixed reactors and immobilized cell reactors to achieve total CO and H/sub 2/ conversion in a retention time of less than two hours, quite good for a biological reactor. Preliminary economic projections indicate that a biological methanation plant with a size of 5 x 10/sup 10/ Btu/day can be economically attractive. 42 refs., 26 figs., 86 tabs.

  8. Analysis of the Sodium-Water Reaction Phenomena by Small Water/Steam Leaks

    International Nuclear Information System (INIS)

    Jeong, J-Y; Kim, T-J; Kim, J-M; Kim, B-H; Park, N-C

    2006-01-01

    One of the important problems to be solved in the design and construction of a sodium cooled fast reactor is to confirm the safety and reliability of the steam generator which transfers the heat from the sodium to the water. Sodium-water reaction events may occur when material faults such as a pinhole or cracks occur in the heat transfer tube wall. When such a leak occurs, evaporating water or superheated steam enters through a small leak into the sodium. The surface of this steam jet reacts with the surrounding sodium. Due to turbulence, sodium and particles of the reaction products are drawn at a high velocity into the jet. Impingement of these particles on an adjacent tube is followed by a combined process of a corrosion and erosion which results in a local weakening of the affected tube. If there is no reliable detection available in time, wastage will ultimately result in an additional leak in the adjacent tube. Therefore, it is very significant to predict these phenomena quantitatively from the view of designing a steam generator and its leak detection systems. The objective of this study is a basic investigating of the sodium-water reaction phenomena by small water/steam leaks

  9. Photocatalytic Water-Splitting Reaction from Catalytic and Kinetic Perspectives

    KAUST Repository

    Hisatomi, Takashi

    2014-10-16

    Abstract: Some particulate semiconductors loaded with nanoparticulate catalysts exhibit photocatalytic activity for the water-splitting reaction. The photocatalysis is distinct from the thermal catalysis because photocatalysis involves photophysical processes in particulate semiconductors. This review article presents a brief introduction to photocatalysis, followed by kinetic aspects of the photocatalytic water-splitting reaction.Graphical Abstract: [Figure not available: see fulltext.

  10. Surface chemical reactions induced by molecules electronically-excited in the gas

    DEFF Research Database (Denmark)

    Petrunin, Victor V.

    2011-01-01

    and alignment are taking place, guiding all the molecules towards the intersections with the ground state PES, where transitions to the ground state PES will occur with minimum energy dissipation. The accumulated kinetic energy may be used to overcome the chemical reaction barrier. While recombination chemical...... be readily produced. Products of chemical adsorption and/or chemical reactions induced within adsorbates are aggregated on the surface and observed by light scattering. We will demonstrate how pressure and spectral dependencies of the chemical outcomes, polarization of the light and interference of two laser...... beams inducing the reaction can be used to distinguish the new process we try to investigate from chemical reactions induced by photoexcitation within adsorbed molecules and/or gas phase photolysis....

  11. kinetics of the coupled gas-iron reactions involving silicon and carbon

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... out for the system involving liquid iron containing carbon and silicon and a gas ... in content with liquid iron at. 15600C, the ... of carbon monoxide bubbles at the. Slag - metal ..... equilibrium strongly make chemical reactions.

  12. An Investigation of the Enolization and Isomeric Products Distribution in the Water Promoted Aldol Reaction of Tropinone and Granatanone

    Directory of Open Access Journals (Sweden)

    Ryszard Lazny

    2016-01-01

    Full Text Available The exo,anti/exo,syn-diastereoselectivity of water promoted direct aldol reactions of tropinone and granatanone (pseudopelletierine is strongly dependent on the amount of water added and aromatic aldehyde used. DFT methods were applied to calculate the free energies of tropinone and granatanone enols, transition states, and isomeric aldol products. A theoretical model was verified by comparison of results from several DFT methods and functionals with experiments. The 6-31g(d/CPCM method proved most suited to the problem, although all methods tested predicted similar trends. Explicit inclusion of a water molecule bonded to the amino ketones resulted in increased stability of the enol forms. The dependence of the anti/syn-diastereoselectivity on the amount of water used may be rationalized on the basis of change in the polarity of the reaction medium. The predicted stabilities of competing products agreed with experimental results supporting the notion of thermodynamic control. The isomeric products distributions for the aldol reaction of several aromatic aldehydes in solventless (neat conditions were accurately calculated from free energies of the aldol addition step in the gas phase using B3LYP/6-31g(d method and in aqueous conditions using the CPCM-B3LYP/6-31g(d model. Our methodology can be useful for predicting the outcome of this type of aldol reactions.

  13. Reduction reactions of water soluble cyano-cobalt(III)-porphyrins: Metal versus ligand centered processes

    International Nuclear Information System (INIS)

    Mosseri, S.; Neta, P.; Harriman, A.; Hambright, P.

    1990-01-01

    Reduction reactions of dicyano-cobalt(III)-porphyrins [potential in vivo cyanide scavenger drugs] were studied by radiolytic and electrochemical methods using the water soluble tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP). For [(CN)2CoIIITPPS]-, reduction occurs stepwise to the CoII, CoI, and finally to the phlorin anion. This behavior is similar to that of the cobalt porphyrins in the absence of cyanide, except that the cyanide ligand shifts the reduction potentials to much more negative values. On the other hand, under radiolytic conditions, [(CN)2CoIIITMPyP]- is reduced on the porphyrin macrocycle by one electron to give the CoIII pi-radical anion, which disproportionates into the initial complex and the two-electron ring reduced CoIII phlorin. The radical anion is also formed by intramolecular electron transfer subsequent to the reaction of CoIITMPyP and cyanide. The results are compared with the chemistry of Vitamin B-12

  14. Study on fine particles influence on sodium sulfite and oxygen gas-liquid reaction

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Shuchang; Zhao, Bo; Wang, Shujuan; Zhuo, Yuqun; Chen, Changhe [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Ministry of Education, Beijing (China). Key Lab. for Thermal Science and Power Engineering

    2013-07-01

    Wet limestone scrubbing is the most common flue gas desulfurization process for control of sulfur dioxide emissions from the combustion of fossil fuels, and forced oxidation is a key part of the reaction. During the reaction which controlled by gas-liquid mass transfer, the fine particles' characteristic, size, solid loading and temperature has a great influence on gas-liquid mass transfer. In the present work is to explain how these factors influence the reaction between Na{sub 2}SO{sub 3} and O{sub 2} and find the best react conditions through experiment. The oxidation rate was experimentally studied by contacting pure oxygen with a sodium sulfite solution with active carbon particle in a stirred tank, and the system pressure drop was record by the pressure sensor. At the beginning the pressure is about 215 kPa and Na{sub 2}SO{sub 3} is about 0.5mol/L. The temperature is 40, 50, 60, 70, 80 C. Compare the results of no particles included, we can conclude that high temperature, proper loadings and smaller particles resulting in higher mass transfer coefficients k{sub L}.

  15. The Value of Water in Extraction of Natural Gas from the Marcellus Shale

    Science.gov (United States)

    Rimsaite, R.; Abdalla, C.; Collins, A.

    2013-12-01

    Hydraulic fracturing of shale has increased the demand for the essential input of water in natural gas production. Increased utilization of water by the shale gas industry, and the development of water transport and storage related infrastructure suggest that the value of water is increasing where hydraulic fracturing is occurring. Few studies on the value of water in industrial uses exist and, to our knowledge, no studies of water's value in extracting natural gas from shale have been published. Our research aims to fill this knowledge gap by exploring several key dimensions of the value of water used in shale gas development. Our primary focus was to document the costs associated with water acquisition for shale gas extraction in West Virginia and Pennsylvania, two states located in the gas-rich Marcellus shale formation with active drilling and extraction underway. This research involved a) gathering data on the sources of and costs associated with water acquisition for shale gas extraction b) comparing unit costs with prices and costs paid by the gas industry users of water; c) determining factors that potentially impact total and per unit costs of water acquisition for the shale gas industry; and d) identifying lessons learned for water managers and policy-makers. The population of interest was all private and public entities selling water to the shale gas industry in Pennsylvania and West Virginia. Primary data were collected from phone interviews with water sellers and secondary data were gathered from state regulatory agencies. Contact information was obtained for 40 water sellers in the two states. Considering both states, the average response rate was 49%. Relatively small amounts of water, approximately 11% in West Virginia and 29% in Pennsylvania, were purchased from public water suppliers by the shale gas industry. The price of water reveals information about the value of water. The average price charged to gas companies was 6.00/1000 gallons and 7

  16. Simultaneous desulfurization and denitrification of flue gas by ·OH radicals produced from O2+ and water vapor in a duct.

    Science.gov (United States)

    Bai, Mindi; Zhang, Zhitao; Bai, Mindong

    2012-09-18

    In the present study, simultaneous flue gas desulfurization and denitrification are achieved with ·OH radicals generated from O(2)(+) reacting with water vapor in a duct. The O(2)(+) ions are generated by a strong ionization dielectric barrier discharge and then injected into the duct. Compared with conventional gas discharge treatment, the present method does not need a plasma reaction reactor, additional catalysts, reductants, or oxidants. The main recovered products are the liquids H(2)SO(4) and HNO(3), which can be used in many processes. Removal rates of 97% for NO and 82% for SO(2) are obtained under the following optimal experimental conditions: molar ratio of reactive oxygen species (O(2)(+), O(3)) to SO(2) and NO, 5; inlet flue gas temperature, 65 °C; reaction time, 0.94 s; and H(2)O volume fraction, 8%. Production of O(2)(+) and the plasma reaction mechanisms are discussed, and the recovered acid is characterized. The experimental results show that the present method performs better for denitrification than for desulfurization. Compared with conventional air discharge flue gas treatments, the present method has lower initial investment and operating costs, and the equipment is more compact.

  17. Overview of light water/hydrogen-based low energy nuclear reactions

    International Nuclear Information System (INIS)

    Miley, George H.; Shrestha, Prajakti J.

    2006-01-01

    This paper reviews light water and hydrogen-based low-energy nuclear reactions (LENRs) including the different methodologies used to study these reactions and the results obtained. Reports of excess heat production, transmutation reactions, and nuclear radiation emission are cited. An aim of this review is to present a summary of the present status of light water LENR research and provide some insight into where this research is heading. (author)

  18. Influence of Shift Work on Manual Dexterity and Reaction Time in Tunisian Nurses.

    Science.gov (United States)

    Merchaoui, Irtyah; Chaari, Neila; Bouhlel, Mohamed; Bouzgarrou, Lamia; Malchaire, Jacques; Akrout, Mohamed

    2017-01-01

    Major effects of shift schedule are related to sleep alertness and performance, but also to long term health outcomes. For nurses, these negative effects have consequences not only on the individual, but also on the workplace, as decreased alertness and reduced job performance could endanger human lives. The specific aim of our study is to assess the influence of shift schedule on nurses´ cognitive ability and rapidity of execution. Our survey is a cross sectional study which had been conducted for 15 months; it involved a sample of 293 participants representative of 1118 nurses working in two Tunisian university hospitals. It included an evaluation of the rapidity of execution performance through the manual dexterity test and the reaction time test. The study was completed by an assessment of the workability Index through a 7- item survey. No association was found between the groups of work schedules and the cognitive ability of execution speed. However, we found a significant decrease in cognitive performance in the nurses exceeding 10 years of job seniority for both schedules. We concluded to an impaired cognitive performance speed in the over 10-year seniority groups in both schedules. Recommendations should be focused on implementing periodic assessment of cognitive performance based on O'Connor finger dexterity test and time reaction test and on implementing effective preventive measures in hospitals after ten years of seniority at work. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  19. Gas phase ion/molecule reactions as studied by Fourier Transform Ion Cyclotron Resonance mass spectrometry

    International Nuclear Information System (INIS)

    Joergensen, S.I.

    1985-01-01

    The subject of this thesis is gas phase ion/molecule reactions as studied by Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry (chapter 2 contains a short description of this method). Three chapters are mainly concerned with mechanistic aspects of gas phase ion/molecule reactions. An equally important aspect of the thesis is the stability and reactivity of α-thio carbanions, dipole stabilized carbanions and homoenolate anions, dealt with in the other four chapters. (Auth.)

  20. Improvements in gas supply systems for heavy-water moderated reactors

    International Nuclear Information System (INIS)

    Aubert, G.; Hassig, J.M.; Laurent, N.; Thomas, B.

    1964-01-01

    In a heavy-water moderated reactor cooled by pressurized gas, an important problem from the point of view, of the reactor block and its economics is the choice of the gas supply system. In the pressure tube solution, the whole of the reactor block structure is at a relatively low temperature, whereas the gas supply equipment is at that of the gas, which is much higher. These parts, through which passes the heat carrying fluid have to present as low a resistance as possible to it so as to avoid costly extra blowing power. Finally, they may only be placed in the reactor block after it has been built; the time required for putting them in position should therefore not be too long. The work reported here concerns the various problems arising in the case of each channel being supplied individually by a tube at the entry and the exit which is connected to a main circuit made up of large size collectors. This individual tubing is sufficiently flexible to absorb the differential expansion and the movement of its ends without stresses or prohibitive reactions being produced; the tubing is also of relatively short length so as to reduce the pressure head of the pressurized gas outside the channels; the small amount of space taken up by the tubing makes it possible to assemble it in a manner which is satisfactory from the point of view both of the time required and of the technical quality. (authors) [fr

  1. Surface water and atmospheric carbon dioxide and nitrous oxide observations by shipboard automated gas chromatography: Results from expeditions between 1977 and 1990

    International Nuclear Information System (INIS)

    Weiss, R.F.; Van Woy, F.A.; Salameh, P.K.; Sepanski, R.J.

    1992-12-01

    This document presents the results of surface water and atmospheric carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) measurements carried out by shipboard gas chromatography over the period 1977--1990. These data include results from 11 different oceanic surveys for a total of 41 expedition legs. Collectively, they represent a globally distributed sampling that includes locations in the Atlantic, Pacific, Indian, and Southern Oceans, as well as the Mediterranean and Red Seas. The measurements were made by an automated high-precision shipboard gas chromatographic system developed during the late 1970s and used extensively over the intervening years. This instrument measures CO 2 by flame ionization after quantitative reaction to methane in a stream of hydrogen. Nitrous oxide is measured by a separate electron capture detector. The chromatographic system measures 196 dry-gas samples a day, divided equally among the atmosphere, gas equilibrated with surface water, a low-range gas standard, and a high-range gas standard

  2. Combination gas producing and waste-water disposal well

    Science.gov (United States)

    Malinchak, Raymond M.

    1984-01-01

    The present invention is directed to a waste-water disposal system for use in a gas recovery well penetrating a subterranean water-containing and methane gas-bearing coal formation. A cased bore hole penetrates the coal formation and extends downwardly therefrom into a further earth formation which has sufficient permeability to absorb the waste water entering the borehole from the coal formation. Pump means are disposed in the casing below the coal formation for pumping the water through a main conduit towards the water-absorbing earth formation. A barrier or water plug is disposed about the main conduit to prevent water flow through the casing except for through the main conduit. Bypass conduits disposed above the barrier communicate with the main conduit to provide an unpumped flow of water to the water-absorbing earth formation. One-way valves are in the main conduit and in the bypass conduits to provide flow of water therethrough only in the direction towards the water-absorbing earth formation.

  3. Gas-Liquid Precipitation of water dissolved heavy metal ions using hydrogen sulfide gas

    NARCIS (Netherlands)

    Al Tarazi, M.Y.M.

    2004-01-01

    Precipitation of solids promoted by gas-liquid reactions is applied in many industrial processes such as the production of ammonium phosphate, ammonium sulphate, barium carbonate, calcium carbonate, calcium fluoride, ypsum (calcium sulphate), goethite, sodium bicarbonate, strontium carbonate and

  4. [Shifting path of industrial pollution gravity centers and its driving mechanism in Pan-Yangtze River Delta].

    Science.gov (United States)

    Zhao, Hai-Xia; Jiang, Xiao-Wei; Cui, Jian-Xin

    2014-11-01

    Shifting path of industrial pollution gravity centers is the response of environmental special formation during the industry transfer process, in order to prove the responding of industrial pollution gravity centers to industry transfer in economically developed areas, this paper calculates the gravity centers of industrial wastewater, gas and solid patterns and reveals the shifting path and its driving mechanism, using the data of industrial pollution in the Pan-Yangtze River Delta from 2000 to 2010. The results show that the gravity center of the industrial waste in Pan-Yangtze River Delta shifts for sure in the last 10 years, and gravity center of solid waste shifts the maximum distance within the three wastes, which was 180.18 km, and shifting distances for waste gas and waste water were 109.51 km and 85.92 km respectively. Moreover, the gravity center of the industrial waste in Pan-Yangtze River Delta shifts westwards, and gravity centers of waste water, gas and solid shift for 0.40 degrees, 0.17 degrees and 0.03 degrees respectively. The shifting of industrial pollution gravity centers is driven by many factors. The rapid development of the heavy industry in Anhui and Jiangxi provinces results in the westward shifting of the pollutions. The optimization and adjustment of industrial structures in Yangtze River Delta region benefit to alleviating industrial pollution, and high-polluting industries shifted to Anhui and Jiangxi provinces promotes pollution gravity center shifting to west. While the development of massive clean enterprise, strong environmental management efforts and better environmental monitoring system slow the shifting trend of industrial pollution to the east in Yangtze River Delta. The study of industrial pollution gravity shift and its driving mechanism provides a new angle of view to analyze the relationship between economic development and environmental pollution, and also provides academic basis for synthetical management and control of

  5. Water vapor and gas transport through PEO PBT block copolymers

    NARCIS (Netherlands)

    Metz, S.J.; Potreck, Jens; Mulder, M.H.V.; Wessling, Matthias

    2002-01-01

    Introduction At the bore well natural gas is saturated with water. Downstream the presence of water may cause: formation of methane hydrates (blocking eventually the pipeline), condensation of water in the pipeline and corrosion effects. A process used for the dehydration of natural gas is glycol

  6. Liquid and Gas Phase Chemistry of Hypergolic Reactions between MMH and NTO or RFNA

    Science.gov (United States)

    Black, Ariel

    Hypergolic systems rely on fuel and oxidizer propellant combinations that spontaneously ignite upon contact. Monomethylhydrazine (MMH) fuel and nitrogen tetroxide (NTO) - based oxidizers embody the state of the art for hypergolic propellants, although the health and safety hazards associated with these propellants demand investigation into less-toxic, high performance alternatives. In order to replicate the combustion characteristics of these highly reactive propellants, a detailed understanding of the full reaction process is necessary. Current reaction mechanisms and hypergolic ignition models generally assume that gas-phase chemistry dominates the interaction since the liquid-phase reactions occur on the order of microseconds. However, condensed-phase reactions produce intermediates integral to gas-phase initiation and development. Additional insight into the physical and chemical processes that dictate this liquid-phase chemistry is therefore essential. Concurrently, further examination of the gas-phase reactions leading to and immediately following ignition is also needed. A method devoted to the determination of the liquid phase hypergolic reaction mechanism and kinematic rate parameters for MMH-NTO and MMH-red fuming nitric acid (RFNA) is presented in this study. MMH-RFNA reaction chemistry is better understood and documented in literature than MMH-NTO and is examined for comparison and validation. Drop on pool experiments at a range of temperatures were initially undertaken using MMH and RFNA and then modified to accommodate the high vapor pressure of NTO. Using a temperature and atmosphere controlled droplet contact chamber, the liquid phases of MMH-RFNA and MMH-NTO were studied by capturing impacts at frame rates from 100,000 to 500,000 fps. This footage allowed for the identification of time delays between droplet contact and initial gas formation, enabling calibration of the Arrhenius pre-exponential factors and activation energies for a global, one

  7. Liquid chromatographic determination of water

    Science.gov (United States)

    Fortier, N.E.; Fritz, J.S.

    1990-11-13

    A sensitive method for the determination of water in the presence of common interferences is presented. The detection system is based on the effect of water on the equilibrium which results from the reaction aryl aldehydes, such as cinnamaldehyde and methanol in the eluent to form cinnamaldehyde dimethylacetal, plus water. This equilibrium is shifted in a catalytic atmosphere of a hydrogen ion form past column reactor. The extent of the shift and the resulting change in absorbance are proportional to the amount of water present. 1 fig.

  8. Chemical looping coal gasification with calcium ferrite and barium ferrite via solid–solid reactions

    International Nuclear Information System (INIS)

    Siriwardane, Ranjani; Riley, Jarrett; Tian, Hanjing; Richards, George

    2016-01-01

    Highlights: • BaFe 2 O 4 and CaFe 2 O 4 are excellent for chemical looping coal gasification. • BaFe 2 O 4 and CaFe 2 O 4 have minimal reactivity with synthesis gas. • Steam enhances the gasification process with these oxygen carriers. • Reaction rates of steam gasification of coal with CaFe 2 O 4 was better than with gaseous oxygen. • Coal gasification appears to be via solid–solid interaction with the oxygen carrier. - Abstract: Coal gasification to produce synthesis gas by chemical looping was investigated with two oxygen carriers, barium ferrite (BaFe 2 O 4 ) and calcium ferrite (CaFe 2 O 4 ). Thermo-gravimetric analysis (TGA) and fixed-bed flow reactor data indicated that a solid–solid interaction occurred between oxygen carriers and coal to produce synthesis gas. Both thermodynamic analysis and experimental data indicated that BaFe 2 O 4 and CaFe 2 O 4 have high reactivity with coal but have a low reactivity with synthesis gas, which makes them very attractive for the coal gasification process. Adding steam increased the production of hydrogen (H 2 ) and carbon monoxide (CO), but carbon dioxide (CO 2 ) remained low because these oxygen carriers have minimal reactivity with H 2 and CO. Therefore, the combined steam–oxygen carrier produced the highest quantity of synthesis gas. It appeared that neither the water–gas shift reaction nor the water splitting reaction promoted additional H 2 formation with the oxygen carriers when steam was present. Wyodak coal, which is a sub-bituminous coal, had the best gasification yield with oxygen carrier–steam while Illinois #6 coal had the lowest. The rate of gasification and selectivity for synthesis gas production was significantly higher when these oxygen carriers were present during steam gasification of coal. The rates and synthesis gas yields during the temperature ramps of coal–steam with oxygen carriers were better than with gaseous oxygen.

  9. Shale gas development impacts on surface water quality in Pennsylvania

    Science.gov (United States)

    Olmstead, Sheila M.; Muehlenbachs, Lucija A.; Shih, Jhih-Shyang; Chu, Ziyan; Krupnick, Alan J.

    2013-01-01

    Concern has been raised in the scientific literature about the environmental implications of extracting natural gas from deep shale formations, and published studies suggest that shale gas development may affect local groundwater quality. The potential for surface water quality degradation has been discussed in prior work, although no empirical analysis of this issue has been published. The potential for large-scale surface water quality degradation has affected regulatory approaches to shale gas development in some US states, despite the dearth of evidence. This paper conducts a large-scale examination of the extent to which shale gas development activities affect surface water quality. Focusing on the Marcellus Shale in Pennsylvania, we estimate the effect of shale gas wells and the release of treated shale gas waste by permitted treatment facilities on observed downstream concentrations of chloride (Cl−) and total suspended solids (TSS), controlling for other factors. Results suggest that (i) the treatment of shale gas waste by treatment plants in a watershed raises downstream Cl− concentrations but not TSS concentrations, and (ii) the presence of shale gas wells in a watershed raises downstream TSS concentrations but not Cl− concentrations. These results can inform future voluntary measures taken by shale gas operators and policy approaches taken by regulators to protect surface water quality as the scale of this economically important activity increases. PMID:23479604

  10. Hydrogen production by water dissociation using ceramic membranes - annual report for FY 2010.

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J. (Energy Systems)

    2011-03-14

    The objective of this project is to develop dense ceramic membranes that can produce hydrogen via coal/coal gas-assisted water dissociation without using an external power supply or circuitry. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen using OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

  11. Safety distance between underground natural gas and water pipeline facilities

    International Nuclear Information System (INIS)

    Mohsin, R.; Majid, Z.A.; Yusof, M.Z.

    2014-01-01

    A leaking water pipe bursting high pressure water jet in the soil will create slurry erosion which will eventually erode the adjacent natural gas pipe, thus causing its failure. The standard 300 mm safety distance used to place natural gas pipe away from water pipeline facilities needs to be reviewed to consider accidental damage and provide safety cushion to the natural gas pipe. This paper presents a study on underground natural gas pipeline safety distance via experimental and numerical approaches. The pressure–distance characteristic curve obtained from this experimental study showed that the pressure was inversely proportional to the square of the separation distance. Experimental testing using water-to-water pipeline system environment was used to represent the worst case environment, and could be used as a guide to estimate appropriate safety distance. Dynamic pressures obtained from the experimental measurement and simulation prediction mutually agreed along the high-pressure water jetting path. From the experimental and simulation exercises, zero effect distance for water-to-water medium was obtained at an estimated horizontal distance at a minimum of 1500 mm, while for the water-to-sand medium, the distance was estimated at a minimum of 1200 mm. - Highlights: • Safe separation distance of underground natural gas pipes was determined. • Pressure curve is inversely proportional to separation distance. • Water-to-water system represents the worst case environment. • Measured dynamic pressures mutually agreed with simulation results. • Safe separation distance of more than 1200 mm should be applied

  12. Slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures

    Science.gov (United States)

    Aines, Roger D.; Bourcier, William L.; Viani, Brian

    2013-01-29

    A slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures includes the steps of dissolving the gas mixture and carbon dioxide in water providing a gas, carbon dioxide, water mixture; adding a porous solid media to the gas, carbon dioxide, water mixture forming a slurry of gas, carbon dioxide, water, and porous solid media; heating the slurry of gas, carbon dioxide, water, and porous solid media producing steam; and cooling the steam to produce purified water and carbon dioxide.

  13. Integrated Microfluidic Gas Sensors for Water Monitoring

    Science.gov (United States)

    Zhu, L.; Sniadecki, N.; DeVoe, D. L.; Beamesderfer, M.; Semancik, S.; DeVoe, D. L.

    2003-01-01

    A silicon-based microhotplate tin oxide (SnO2) gas sensor integrated into a polymer-based microfluidic system for monitoring of contaminants in water systems is presented. This device is designed to sample a water source, control the sample vapor pressure within a microchannel using integrated resistive heaters, and direct the vapor past the integrated gas sensor for analysis. The sensor platform takes advantage of novel technology allowing direct integration of discrete silicon chips into a larger polymer microfluidic substrate, including seamless fluidic and electrical interconnects between the substrate and silicon chip.

  14. Alteration of natural (37)Ar activity concentration in the subsurface by gas transport and water infiltration.

    Science.gov (United States)

    Guillon, Sophie; Sun, Yunwei; Purtschert, Roland; Raghoo, Lauren; Pili, Eric; Carrigan, Charles R

    2016-05-01

    High (37)Ar activity concentration in soil gas is proposed as a key evidence for the detection of underground nuclear explosion by the Comprehensive Nuclear Test-Ban Treaty. However, such a detection is challenged by the natural background of (37)Ar in the subsurface, mainly due to Ca activation by cosmic rays. A better understanding and improved capability to predict (37)Ar activity concentration in the subsurface and its spatial and temporal variability is thus required. A numerical model integrating (37)Ar production and transport in the subsurface is developed, including variable soil water content and water infiltration at the surface. A parameterized equation for (37)Ar production in the first 15 m below the surface is studied, taking into account the major production reactions and the moderation effect of soil water content. Using sensitivity analysis and uncertainty quantification, a realistic and comprehensive probability distribution of natural (37)Ar activity concentrations in soil gas is proposed, including the effects of water infiltration. Site location and soil composition are identified as the parameters allowing for a most effective reduction of the possible range of (37)Ar activity concentrations. The influence of soil water content on (37)Ar production is shown to be negligible to first order, while (37)Ar activity concentration in soil gas and its temporal variability appear to be strongly influenced by transient water infiltration events. These results will be used as a basis for practical CTBTO concepts of operation during an OSI. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. A Safe and Efficient Technique for the Production of HCl/DCl Gas

    Science.gov (United States)

    Mayer, Steven G.; Bard, Raymond R.; Cantrell, Kevin

    2008-01-01

    We present a safe and efficient technique to generate HCl/DCl gas for use in the classic physical chemistry experiment that introduces students to ro-vibrational spectroscopy. The reaction involves thionyl chloride and a mixture of water and deuterium oxide to produce HCl/DCl gas with SO[subscript 2] gas as a byproduct. The entire reaction is…

  16. An Equilibrium-Based Model of Gas Reaction and Detonation

    International Nuclear Information System (INIS)

    Trowbridge, L.D.

    2000-01-01

    During gaseous diffusion plant operations, conditions leading to the formation of flammable gas mixtures may occasionally arise. Currently, these could consist of the evaporative coolant CFC-114 and fluorinating agents such as F2 and ClF3. Replacement of CFC-114 with a non-ozone-depleting substitute is planned. Consequently, in the future, the substitute coolant must also be considered as a potential fuel in flammable gas mixtures. Two questions of practical interest arise: (1) can a particular mixture sustain and propagate a flame if ignited, and (2) what is the maximum pressure that can be generated by the burning (and possibly exploding) gas mixture, should it ignite? Experimental data on these systems, particularly for the newer coolant candidates, are limited. To assist in answering these questions, a mathematical model was developed to serve as a tool for predicting the potential detonation pressures and for estimating the composition limits of flammability for these systems based on empirical correlations between gas mixture thermodynamics and flammability for known systems. The present model uses the thermodynamic equilibrium to determine the reaction endpoint of a reactive gas mixture and uses detonation theory to estimate an upper bound to the pressure that could be generated upon ignition. The model described and documented in this report is an extended version of related models developed in 1992 and 1999

  17. Sodium-water reaction test facility (SWAT-3)

    International Nuclear Information System (INIS)

    Shimazu, Hisashi; Ukechi, Kazutoshi; Sasakura, Kazutake; Kusunoki, Junichi

    1976-01-01

    In the development of the liquid metal cooled fast breeder reactor (LMFBR), the steam generator (SG) is considered one of the most important components. The Power Reactor and Nuclear Fuel Development Corporation (PNC) is now promoting the research and development of the SG system used with the prototype fast breeder reactor ''Monju''. In this research, the phenomena of the sodium-water reaction in the SG are the key which must be investigated for the solution of problems. The test facility (SWAT-3) simulating Monju's SG on the scale of 1/2.5 was designed, fabricated and installed by IHI at Oarai Engineering Center of PNC, its pre-operation being accomplished in February 1975. The purpose of SWAT-3 is summarized as follows: (1) To perform an overall test on the safety of Monju's SG and intermediate heat transport system under the design condition against sodium-water reaction accidents. (2) To investigate the damage of the SG structure caused by the sodium-water reaction, and the possibility of repair and recovery operations. The first test was accomplished successfully on June 9, 1975. As a result of the test, the fundamental function of this test facility was proven to be satisfactory as expected. (auth.)

  18. CARBON DIOXIDE CAPTURE FROM FLUE GAS USING DRY REGENERABLE SORBENTS

    Energy Technology Data Exchange (ETDEWEB)

    David A. Green; Brian S. Turk; Raghubir P. Gupta; Alejandro Lopez-Ortiz; Douglas P. Harrison; Ya Liang

    2001-07-01

    Sodium based sorbents including sodium carbonate may be used to capture carbon dioxide from flue gas. A relatively concentrated carbon dioxide stream may be recoverable for sequestration when the sorbent is regenerated. Electrobalance tests indicated that sodium carbonate monohydrate was formed in a mixture of helium and water vapor at temperatures below 65 C. Additional compounds may also form, but this could not be confirmed. In the presence of carbon dioxide and water vapor, both the initial reaction rate of sodium carbonate with carbon dioxide and water and the sorbent capacity decreased with increasing temperature, consistent with the results from the previous quarter. Increasing the carbon dioxide concentration at constant temperature and water vapor concentration produced a measurable increase in rate, as did increasing the water vapor concentration at constant carbon dioxide concentration and temperature. Runs conducted with a flatter TGA pan resulted in a higher initial reaction rate, presumably due to improved gas-solid contact, but after a short time, there was no significant difference in the rates measured with the different pans. Analyses of kinetic data suggest that the surface of the sodium carbonate particles may be much hotter than the bulk gas due to the highly exothermic reaction with carbon dioxide and water, and that the rate of heat removal from the particle may control the reaction rate. A material and energy balance was developed for a cyclic carbonation/calcination process which captures about 26 percent of the carbon dioxide present in flue gas available at 250 C.

  19. Pervaporation applied for dewatering of reaction mixture during esterification

    OpenAIRE

    Krasiński Andrzej; Wierzba Patrycja; Grudzień Agata; Hajmowicz Halina; Zawada Krzysztof; Synoradzki Ludwik

    2016-01-01

    In this work the esterification of diethyl tartrate was studied. The research was focused on the enhancement of reversible reaction yield, which is accomplished by dewatering of the reaction mixture. The removal of water shifts the equilibrium towards the main product. Pervaporation was applied for this purpose, and results were compared to distillation. The advantages and limitations of both processes are discussed. The experimental part consists of dewatering of mixture after the reaction h...

  20. Effect of temperature on a free energy and equilibrium constants during dry flue gas desulphurisation chemical reactions

    Directory of Open Access Journals (Sweden)

    Kuburović Miloš

    2002-01-01

    Full Text Available During dry flue gas desulphurisation (FGD dry particles of reagents are inserted (injected in the stream of flue gas, where they bond SO2. As reagents, the most often are used compounds of calcium (CaCO3, CaO or Ca(OH2. Knowledge of free energy and equilibrium constants of chemical reactions during dry FGD is necessary for understanding of influence of flue gas temperature to course of these chemical reactions as well as to SO2 bonding from flue gases.

  1. Contribution to the modelling of gas-solid reactions and reactors; Contribution a la modelisation des reactions et des reacteurs gaz-solide

    Energy Technology Data Exchange (ETDEWEB)

    Patisson, F

    2005-09-15

    Gas-solid reactions control a great number of major industrial processes involving matter transformation. This dissertation aims at showing that mathematical modelling is a useful tool for both understanding phenomena and optimising processes. First, the physical processes associated with a gas-solid reaction are presented in detail for a single particle, together with the corresponding available kinetic grain models. A second part is devoted to the modelling of multiparticle reactors. Different approaches, notably for coupling grain models and reactor models, are illustrated through various case studies: coal pyrolysis in a rotary kiln, production of uranium tetrafluoride in a moving bed furnace, on-grate incineration of municipal solid wastes, thermogravimetric apparatus, nuclear fuel making, steel-making electric arc furnace. (author)

  2. Analyte induced water adsorbability in gas phase biosensors: the influence of ethinylestradiol on the water binding protein capacity.

    Science.gov (United States)

    Snopok, Borys; Kruglenko, Ivanna

    2015-05-07

    An ultra-sensitive gas phase biosensor/tracer/bio-sniffer is an emerging technology platform designed to provide real-time information on air-borne analytes, or those in liquids, through classical headspace analysis. The desired bio-sniffer measures gaseous 17α- ethinylestradiol (ETED) as frequency changes on a quartz crystal microbalance (QCM), which is a result of the interactions of liquid sample components in the headspace (ETED and water) with a biorecognition layer. The latter was constructed by immobilization of polyclonal antiserum against a phenolic A-ring of estrogenic receptors through protein A. The QCM response exhibited stretched exponential kinetics of negative frequency shifts with reversible and "irreversible" components of mass uptake onto the sensor surface in static headspace conditions when exposed to water solutions of ETED over the sensor working range, from 10(-10) to 10(-17) g L(-1). It was shown that the variations in the QCM response characteristics are due to the change of the water-binding capacity of the sensing layer induced by protein transformations initiated by the binding of ETED molecules. This result is well correlated with the natural physiological function of estrogens in controlling the homeostasis of body fluids in living beings.

  3. Building America Case Study: Assessment of a Hybrid Retrofit Gas Water Heater

    Energy Technology Data Exchange (ETDEWEB)

    M. Hoeschele, E. Weitzel, C. Backman

    2017-06-01

    This project completed a modeling evaluation of a hybrid gas water heater that combines a reduced capacity tankless unit with a downsized storage tank. This product would meet a significant market need by providing a higher efficiency gas water heater solution for retrofit applications while maintaining compatibility with the half-inch gas lines and standard B vents found in most homes. The TRNSYS simulation tool was used to model a base case 0.60 EF atmospheric gas storage water, a 0.82 EF non-condensing gas tankless water heater, an existing (high capacity) hybrid unit on the market, and an alternative hybrid unit with lower storage volume and reduced gas input requirements.

  4. Photogeochemical reactions of manganese under anoxic conditions

    Science.gov (United States)

    Liu, W.; Yee, N.; Piotrowiak, P.; Falkowski, P. G.

    2017-12-01

    Photogeochemistry describes reactions involving light and naturally occurring chemical species. These reactions often involve a photo-induced electron transfer that does not occur in the absence of light. Although photogeochemical reactions have been known for decades, they are often ignored in geochemical models. In particular, reactions caused by UV radiation during an ozone free early Earth could have influenced the available oxidation states of manganese. Manganese is one of the most abundant transition metals in the crust and is important in both biology and geology. For example, the presence of manganese (VI) oxides in the geologic record has been used as a proxy for oxygenic photosynthesis; however, we suggest that the high oxidation state of Mn can be produced abiotically by photochemical reactions. Aqueous solutions of manganese (II) as well as suspensions of rhodochrosite (MnCO3) were irradiated under anoxic condition using a 450 W mercury lamp and custom built quartz reaction vessels. The photoreaction of the homogeneous solution of Mn(II) produced H2 gas and akhtenskite (ɛ-MnO2) as the solid product . This product is different than the previously identified birnessite. The irradiation of rhodochrosite suspensions also produced H2 gas and resulted in both a spectral shift as well as morphology changes of the mineral particles in the SEM images. These reactions offer alternative, abiotic pathways for the formation of manganese oxides.

  5. Gas phase polymerization of propylene. Reaction kinetics and molecular weight distribution

    NARCIS (Netherlands)

    Meier, G.B.; Weickert, G.; van Swaaij, Willibrordus Petrus Maria

    2001-01-01

    Gas-phase polymerizations have been executed at different temperatures, pressures, and hydrogen concentrations using Me2Si[Ind]2ZrCl2 / methylaluminoxane / SiO2(Pennsylvania Quarts) as a catalyst. The reaction rate curves have been described by a kinetic model, which takes into account the initially

  6. Patrika-September 2015.pmd

    Indian Academy of Sciences (India)

    Latha.Srinivasan

    2015-09-13

    Sep 13, 2015 ... in this area and water gas shift reactions were highlighted. ... of the chemical reactions in carbonate-silicated systems and the ... Synthetic methodologies for generating ..... finding increasing use in decision making by policy.

  7. Studies of the role of water in the electrocatalysis of methanol oxidation

    Science.gov (United States)

    Lin, Andrew S.; Kowalak, Albert D.; O'Grady, William E.

    The oxidation of methanol has been carried out on electrodes prepared by evaporating Pt directly onto a Nafion membrane and then introducing the methanol either in the gas-fed mode or directly from the electrolyte in the electrolyte-fed mode. It was found that the oxidation carried out using a gas-fed electrode was shifted 100-150 mV more cathodic than the electrolyte-fed electrode. A similar set of experiments was carried out using hydrophobic gas-diffusion electrodes and similar results were obtained. These results suggest that the mechanism of the methanol oxidation reaction depends on the nature of the surroundings and the orientation of the methanol with respect to the electrode surface. In the electrolyte-fed configuration the methanol will be in a hydrogen-bonded water cluster allowing the carbon end of the molecule to more readily approach the catalyst surface. While in the gas-fed configuration the methanol will interact with the water or oxidic surface through the hydroxyl end of the molecule. Clearly, these two possible mechanisms will lead to different products and one may enhance the rate of the direct oxidation of methanol as observed in this work.

  8. The deuterium-exchange reaction between water and hydrogen with the thin-film hydrophobic catalyst

    International Nuclear Information System (INIS)

    Yamashita, Hisao; Mizumoto, Mamoru; Matsuda, Shimpei

    1985-01-01

    The deuterium-exchange reaction between water and hydrogen with a hydrophobic catalyst was studied. The hydrophobic catalyst was composed of platinum as an active component and porous poly(tetrafluoroethylene) (PTFE) as a support. The PTFE support was in two forms, i.e., (a) a pellet and (b) a thin-film with the thickness of 50 μm. The primary purpose of the thin film hydrophobic catalyst was to reduce the platinum usage in the reactor. The activity of the catalyst was measured in a trickle bed reactor at atmospheric pressure and temperature of 20 ∼ 70 deg C. It has been found that the employment of the thin-film catalyst reduced the platinum usage to 1/5 of the reactor in the case of using a conventional catalyst. Platinum particles on the thin-film catalyst work efficiently because the reactants were easily diffused to the active sites. It has also been found that the isotopic exchange rate with the thin-film catalyst increased with the increase in the ratio of liquid/gas and increased with the rise of the reaction temperature. It was found from an endurance test that the activity of the thin-film catalyst decreased gradually due to the condensation of water vapor in the catalyst, but was regenarated by heating the catalyst to remove the condensed water. (author)

  9. ICR studies of some anionic gas phase reactions and FTICR software design

    International Nuclear Information System (INIS)

    Noest, A.J.

    1983-01-01

    This thesis consists of two parts. Part one (Chs. 1-5) reports experimental results from mostly drift-cell ICR studies of negative ion-molecule reactions; part two (Chs. 6-11) concerns the design of software for an FTICR instrument. The author discusses successively: 1. ion cyclotron resonance spectrometry; 2. the gas phase allyl anion; 3. the (M-H) and (M-H2) anions from acetone; 4. negative ion-molecule reactions of aliphatic nitrites studied by cyclotron resonance; 5. homoconjugation versus charge-dipole interaction effects in the stabilization of carbanions in the gas phase; 6. the Fourier Transform ICR method; 7. the FTICR-software; 8. an efficient adaptive matcher filter for fast transient signals; 9. reduction of spectral peak height errors by time-domain weighing; 10. Chirp excitation; 11. Compact data storage. The book concludes with a Dutch and English summary (G.J.P.)

  10. Seasonal photosynthetic gas exchange and water-use efficiency in a constitutive CAM plant, the giant saguaro cactus (Carnegiea gigantea).

    Science.gov (United States)

    Bronson, Dustin R; English, Nathan B; Dettman, David L; Williams, David G

    2011-11-01

    Crassulacean acid metabolism (CAM) and the capacity to store large quantities of water are thought to confer high water use efficiency (WUE) and survival of succulent plants in warm desert environments. Yet the highly variable precipitation, temperature and humidity conditions in these environments likely have unique impacts on underlying processes regulating photosynthetic gas exchange and WUE, limiting our ability to predict growth and survival responses of desert CAM plants to climate change. We monitored net CO(2) assimilation (A(net)), stomatal conductance (g(s)), and transpiration (E) rates periodically over 2 years in a natural population of the giant columnar cactus Carnegiea gigantea (saguaro) near Tucson, Arizona USA to investigate environmental and physiological controls over carbon gain and water loss in this ecologically important plant. We hypothesized that seasonal changes in daily integrated water use efficiency (WUE(day)) in this constitutive CAM species would be driven largely by stomatal regulation of nighttime transpiration and CO(2) uptake responding to shifts in nighttime air temperature and humidity. The lowest WUE(day) occurred during time periods with extreme high and low air vapor pressure deficit (D(a)). The diurnal with the highest D(a) had low WUE(day) due to minimal net carbon gain across the 24 h period. Low WUE(day) was also observed under conditions of low D(a); however, it was due to significant transpiration losses. Gas exchange measurements on potted saguaro plants exposed to experimental changes in D(a) confirmed the relationship between D(a) and g(s). Our results suggest that climatic changes involving shifts in air temperature and humidity will have large impacts on the water and carbon economy of the giant saguaro and potentially other succulent CAM plants of warm desert environments.

  11. Bacterial Community Shift Drives Antibiotic Resistance Promotion during Drinking Water Chlorination.

    Science.gov (United States)

    Jia, Shuyu; Shi, Peng; Hu, Qing; Li, Bing; Zhang, Tong; Zhang, Xu-Xiang

    2015-10-20

    For comprehensive insights into the effects of chlorination, a widely used disinfection technology, on bacterial community and antibiotic resistome in drinking water, this study applied high-throughput sequencing and metagenomic approaches to investigate the changing patterns of antibiotic resistance genes (ARGs) and bacterial community in a drinking water treatment and distribution system. At genus level, chlorination could effectively remove Methylophilus, Methylotenera, Limnobacter, and Polynucleobacter, while increase the relative abundance of Pseudomonas, Acidovorax, Sphingomonas, Pleomonas, and Undibacterium in the drinking water. A total of 151 ARGs within 15 types were detectable in the drinking water, and chlorination evidently increased their total relative abundance while reduced their diversity in the opportunistic bacteria (p < 0.05). Residual chlorine was identified as the key contributing factor driving the bacterial community shift and resistome alteration. As the dominant persistent ARGs in the treatment and distribution system, multidrug resistance genes (mainly encoding resistance-nodulation-cell division transportation system) and bacitracin resistance gene bacA were mainly carried by chlorine-resistant bacteria Pseudomonas and Acidovorax, which mainly contributed to the ARGs abundance increase. The strong correlation between bacterial community shift and antibiotic resistome alteration observed in this study may shed new light on the mechanism behind the chlorination effects on antibiotic resistance.

  12. Evaluation of Mars CO2 Capture and Gas Separation Technologies

    Science.gov (United States)

    Muscatello, Anthony C.; Santiago-Maldonado, Edgardo; Gibson, Tracy; Devor, Robert; Captain, James

    2011-01-01

    Recent national policy statements have established that the ultimate destination of NASA's human exploration program is Mars. In Situ Resource Utilization (ISRU) is a key technology required to ,enable such missions and it is appropriate to review progress in this area and continue to advance the systems required to produce rocket propellant, oxygen, and other consumables on Mars using the carbon dioxide atmosphere and other potential resources. The Mars Atmospheric Capture and Gas separation project is selecting, developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Trace gases will be required to be separated from Martian atmospheric gases to provide pure CO2 to processing elements. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and should be captured as well. To achieve these goals, highly efficient gas separation processes will be required. These gas separation techniques are also required across various areas within the ISRU project to support various consumable production processes. The development of innovative gas separation techniques will evaluate the current state-of-the-art for the gas separation required, with the objective to demonstrate and develop light-weight, low-power methods for gas separation. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from unreacted carbon oxides (C02-CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, (3)/carbon oxides from oxygen from a trash/waste processing reaction, and (4) helium from hydrogen or oxygen from a propellant scavenging process. Potential technologies for the separations include' freezers, selective membranes, selective solvents, polymeric sorbents

  13. Plant water use efficiency over geological time--evolution of leaf stomata configurations affecting plant gas exchange.

    Science.gov (United States)

    Assouline, Shmuel; Or, Dani

    2013-01-01

    Plant gas exchange is a key process shaping global hydrological and carbon cycles and is often characterized by plant water use efficiency (WUE - the ratio of CO2 gain to water vapor loss). Plant fossil record suggests that plant adaptation to changing atmospheric CO2 involved correlated evolution of stomata density (d) and size (s), and related maximal aperture, amax . We interpreted the fossil record of s and d correlated evolution during the Phanerozoic to quantify impacts on gas conductance affecting plant transpiration, E, and CO2 uptake, A, independently, and consequently, on plant WUE. A shift in stomata configuration from large s-low d to small s-high d in response to decreasing atmospheric CO2 resulted in large changes in plant gas exchange characteristics. The relationships between gas conductance, gws , A and E and maximal relative transpiring leaf area, (amax ⋅d), exhibited hysteretic-like behavior. The new WUE trend derived from independent estimates of A and E differs from established WUE-CO2 trends for atmospheric CO2 concentrations exceeding 1,200 ppm. In contrast with a nearly-linear decrease in WUE with decreasing CO2 obtained by standard methods, the newly estimated WUE trend exhibits remarkably stable values for an extended geologic period during which atmospheric CO2 dropped from 3,500 to 1,200 ppm. Pending additional tests, the findings may affect projected impacts of increased atmospheric CO2 on components of the global hydrological cycle.

  14. Simulation bidimensional of water and gas alternative injection; Simulacao bidimensional de injecao alternada de agua e gas

    Energy Technology Data Exchange (ETDEWEB)

    Santana, Ana Paula Silva C. de

    1999-07-01

    This dissertation presents a study of the unidimensional of water and gas alternate injection (WAG) using the stream line theory. It is considered incompressible fluid., unit mobility ratio, negligible capillary and gravitational effects, homogeneous and isotropic reservoir, isothermal flow two phases, oil and water, and three components, oil, water and gas. In the stream line theory, the following injection schemes are considered: staggered line five-spot, direct line and seven-spot. It is also considered that there is no flow among the streams. In the WAG calculations it is used the fractional flow theory and the method of characteristics, which consists of shock waves and rarefactions. The composition of these waves is said compatible if it satisfies the entropy condition. The solution goes through a certain path from the left to the right side constrained by the initial and boundary conditions. The gas injection is at a high pressure to ensure miscible displacement. It is considered first injection of a water bank and then, injection of a gas bank. We concluded that the gas injection at a high pressure recoveries all residual oil and the water saturation remains is greater than initial saturation. (author)

  15. Supercritical water decontamination of town gas soil

    International Nuclear Information System (INIS)

    Kocher, B.S.; Azzam, F.O.; Lee, S.

    1994-01-01

    Town gas sites represent a large environmental problem that exists in more than 2,000 sites across North America alone. The major contaminants in town gas sods are polycyclic aromatic hydrocarbons (PAHs). These are stable compounds that migrate deep into the soil and are traditionally very difficult to remove by conventional remediation processes. Supercritical fluids offer enhanced solvating properties along with reduced mass transfer resistances that make them ideal for removing compounds that are difficult or impossible to remove by conventional processes. Supercritical water is ideal for removing PAHs and other hydrocarbons from soil due to its high solvating power towards most hydrocarbon species. Supercritical water was investigated for its ability to remediate two different town gas sods containing from 3--20 wt% contamination. The sod was remediated in a 300-cc semi-continuous system to a more environmentally acceptable level

  16. Reaction pathways for catalytic gas-phase oxidation of glycerol over mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Suprun, W.; Glaeser, R.; Papp, H. [Leipzig Univ. (Germany). Inst. of Chemical Technology

    2011-07-01

    Glycerol as a main by-product from bio-diesel manufacture is a cheap raw material with large potential for chemical or biochemical transformations to value-added C3-chemicals. One possible way of glycerol utilization involves its catalytic oxidation to acrylic acid as an alternative to petrochemical routes. However, this catalytic conversion exhibits various problems such as harsh reaction conditions, severe catalyst coking and large amounts of undesired by-products. In this study, the reaction pathways for gas-phase conversion of glycerol over transition metal oxides (Mo, V und W) supported on TiO{sub 2} and SiO{sub 2} were investigated by two methods: (i) steady state experiments of glycerol oxidation and possible reactions intermediates, i.e., acrolein, 3-hydroxy propionaldehyde and acetaldehyde, and (ii) temperature-programmed surface reaction (TPSR) studies of glycerol conversion in the presence and in the absence of gas-phase oxygen. It is shown that the supported W-, V and Mo-oxides possess an ability to catalyze the oxidation of glycerol to acrylic acid. These investigations allowed us to gain a deeper insight into the reaction mechanism. Thus, based on the obtained results, three possible reactions pathways for the selective oxidation of glycerol to acrylic acid on the transition metal-containing catalysts are proposed. The major pathways in presence of molecular oxygen are a fast successive destructive oxidation of glycerol to CO{sub x} and the dehydration of glycerol to acrolein which is a rate-limiting step. (orig.)

  17. Building America Case Study: Assessment of a Hybrid Retrofit Gas Water Heater

    Energy Technology Data Exchange (ETDEWEB)

    2017-06-19

    This project completed a modeling evaluation of a hybrid gas water heater that combines a reduced capacity tankless unit with a downsized storage tank. This product would meet a significant market need by providing a higher efficiency gas water heater solution for retrofit applications while maintaining compatibility with the half-inch gas lines and standard B vents found in most homes. The TRNSYS simulation tool was used to model a base case 0.60 EF atmospheric gas storage water, a 0.82 EF non-condensing gas tankless water heater, an existing (high capacity) hybrid unit on the market, and an alternative hybrid unit with lower storage volume and reduced gas input requirements. Simulations were completed under a 'peak day' sizing scenario with 183 gpd hot water loads in a Minnesota winter climate case. Full-year simulations were then completed in three climates (ranging from Phoenix to Minneapolis) for three hot water load scenarios (36, 57, and 96 gpd). Model projections indicate that the alternative hybrid offers an average 4.5% efficiency improvement relative to the 0.60 EF gas storage unit across all scenarios modeled. The alternative hybrid water heater evaluated does show promise, but the current low cost of natural gas across much of the country and the relatively small incremental efficiency improvement poses challenges in initially building a market demand for the product.

  18. Lithium recovery from shale gas produced water using solvent extraction

    International Nuclear Information System (INIS)

    Jang, Eunyoung; Jang, Yunjai; Chung, Eunhyea

    2017-01-01

    Shale gas produced water is hypersaline wastewater generated after hydraulic fracturing. Since the produced water is a mixture of shale formation water and fracturing fluid, it contains various organic and inorganic components, including lithium, a useful resource for such industries as automobile and electronics. The produced water in the Marcellus shale area contains about 95 mg/L lithium on average. This study suggests a two-stage solvent extraction technique for lithium recovery from shale gas produced water, and determines the extraction mechanism of ions in each stage. All experiments were conducted using synthetic shale gas produced water. In the first-stage, which was designed for the removal of divalent cations, more than 94.4% of Ca"2"+, Mg"2"+, Sr"2"+, and Ba"2"+ ions were removed by using 1.0 M di-(2-ethylhexyl) phosphoric acid (D2EHPA) as an extractant. In the second-stage, for lithium recovery, we could obtain a lithium extraction efficiency of 41.2% by using 1.5 M D2EHPA and 0.3 M tributyl phosphate (TBP). Lithium loss in the first-stage was 25.1%, and therefore, the total amount of lithium recovered at the end of the two-step extraction procedure was 30.8%. Through this study, lithium, one of the useful mineral resources, could be selectively recovered from the shale gas produced water and it would also reduce the wastewater treatment cost during the development of shale gas. - Highlights: • Lithium was extracted from shale gas produced water using an organic solvent. • Two-stage solvent extraction technique was applied. • Divalent cations were removed in the first stage by D2EHPA. • Lithium was selectively recovered in the second stage by using TBP with D2EHPA.

  19. Thermodynamic Modeling of Natural Gas Systems Containing Water

    DEFF Research Database (Denmark)

    Karakatsani, Eirini K.; Kontogeorgis, Georgios M.

    2013-01-01

    As the need for dew point specifications remains very urgent in the natural gas industry, the development of accurate thermodynamic models, which will match experimental data and will allow reliable extrapolations, is needed. Accurate predictions of the gas phase water content in equilibrium...... with a heavy phase were previously obtained using cubic plus association (CPA) coupled with a solid phase model in the case of hydrates, for the binary systems of water–methane and water–nitrogen and a few natural gas mixtures. In this work, CPA is being validated against new experimental data, both water...... content and phase equilibrium data, and solid model parameters are being estimated for four natural gas main components (methane, ethane, propane, and carbon dioxide). Different tests for the solid model parameters are reported, including vapor-hydrate-equilibria (VHE) and liquid-hydrate-equilibria (LHE...

  20. A plug flow model for chemical reactions and aerosol nucleation and growth in an alkali-containing flue gas

    DEFF Research Database (Denmark)

    Christensen, K. A.; Livbjerg, Hans

    2000-01-01

    multicomponent growth models are treated. The local gas phase composition is determined from a gas phase chemical equilibrium calculation combined with finite reaction rate kinetics for slower reactions. The model is useful in the analysis of boiler operation with respect to the formation of particles, HCl, SO2......The paper presents a numerical model for the simulation of gas to particle conversion and the chemical changes during cooling of a flue gas from the combustion of fuels rich in volatile alkali species. For the homogeneous nucleation of alkali species the model uses the classical theory modified...

  1. Isotope exchange reaction on solid breeder materials

    International Nuclear Information System (INIS)

    Baba, A.; Nishikawa, M.; Eguchi, T.; Kawagoe, T.

    2000-01-01

    Lithium ceramic materials such as Li 2 O, LiAlO 2 , Li 2 ZrO 3 , Li 2 TiO 3 and Li 4 SiO 4 are considered to be as candidate for the tritium breeding material in a deuterium-tritium (D-T) fusion reactor. In the recent blanket designs, helium gas with hydrogen or deuterium is planned to be used as the blanket purge gas to reduce tritium inventory and promote tritium release from the breeding material. In addition, the rate of isotope exchange reaction between hydrogen isotopes in the purge gas and tritium on the surface of the breeding material is necessary to analyze the tritium release behavior from the breeding materials. However, the rate of isotope exchange reactions between hydrogen isotopes in the purge gas and tritium on the surface of those materials has not been quantified until recently. Recently, the present authors quantified the rate of isotope exchange reaction on Li 2 O and Li 2 ZrO 3 . The overall mass transfer coefficients representing the isotope exchange reaction between H 2 and D 2 O on breeding materials or the same between D 2 and H 2 O are experimentally obtained in this study. Comparison to isotope exchange reaction rates on various breeding materials is also performed in this study. Discussions about the effects of temperature, concentration of hydrogen in the purge gas or flow rate of the purge gas on the conversion of tritiated water to tritium gas are also performed

  2. Diels-Alder reactions in water : Enforced hydrophobic interaction and hydrogen bonding

    NARCIS (Netherlands)

    Engberts, Jan B.F.N.

    1995-01-01

    Second-order rate constants have been measured for the Diels-Alder (DA) reactions of cyclopentadiene with dienophiles of varying hydrophobicity and hydrogen-bond acceptor capacity in water, in a series of organic solvents and in alcohol-water mixtures. The intramolecular DA reaction of

  3. DIELS-ALDER REACTIONS IN WATER - ENFORCED HYDROPHOBIC INTERACTION AND HYDROGEN-BONDING

    NARCIS (Netherlands)

    Engberts, J.B.F.N.

    Second-order rate constants have been measured for the Diels-Alder (DA) reactions of cyclopentadiene with dienophiles of varying hydrophobicity and hydrogen-bond acceptor capacity in water, in a series of organic solvents and in alcohol-water mixtures. The intramolecular DA reaction of

  4. Ultrasound-mediated drug delivery by gas bubbles generated from a chemical reaction.

    Science.gov (United States)

    Lee, Sungmun; Al-Kaabi, Leena; Mawart, Aurélie; Khandoker, Ahsan; Alsafar, Habiba; Jelinek, Herbert F; Khalaf, Kinda; Park, Ji-Ho; Kim, Yeu-Chun

    2018-02-01

    Highly echogenic and ultrasound-responsive microbubbles such as nitrogen and perfluorocarbons have been exploited as ultrasound-mediated drug carriers. Here, we propose an innovative method for drug delivery using microbubbles generated from a chemical reaction. In a novel drug delivery system, luminol encapsulated in folate-conjugated bovine serum albumin nanoparticles (Fol-BSAN) can generate nitrogen gas (N 2 ) by chemical reaction when it reacts with hydrogen peroxide (H 2 O 2 ), one of reactive oxygen species (ROS). ROS plays an important role in the initiation and progression of cancer and elevated ROS have been observed in cancer cells both in vitro and in vivo. High-intensity focussed ultrasound (HIFU) is used to burst the N 2 microbubbles, causing site-specific delivery of anticancer drugs such as methotrexate. In this research, the drug delivery system was optimised by using water-soluble luminol and Mobil Composition of Matter-41 (MCM-41), a mesoporous material, so that the delivery system was sensitive to micromolar concentrations of H 2 O 2 . HIFU increased the drug release from Fol-BSAN by 52.9 ± 2.9% in 10 minutes. The cytotoxicity of methotrexate was enhanced when methotrexate is delivered to MDA-MB-231, a metastatic human breast cancer cell line, using Fol-BSAN with HIFU. We anticipate numerous applications of chemically generated microbubbles for ultrasound-mediated drug delivery.

  5. Sugarcane bagasse gasification: Global reaction mechanism of syngas evolution

    International Nuclear Information System (INIS)

    Ahmed, I.I.; Gupta, A.K.

    2012-01-01

    Highlights: ► Gasification of sugarcane bagasse has been investigated using a semi batch reactor. ► Global reaction mechanism combining pyrolysis and gasification reactions is presented. ► High flow rates of syngas supported fragmentation and secondary reactions. ► CO flow rate increased at higher heating rates at the expense of CO 2 production. ► At high temperatures merger between pyrolysis and char gasification occurs. -- Abstract: Steam gasification of sugarcane bagasse has been investigated. A semi batch reactor with a fixed amount of sugarcane bagasse sample placed in steady flow of high temperature steam at atmospheric pressure has been used. The gasification of bagasse was examined at reactor and steam temperatures of 800, 900 and 1000 °C. The evolution of syngas flow rate and chemical composition has been monitored. The evolution of chemical composition and total flow rate of the syngas has been used to formulate a global reaction mechanism. The mechanism combines pyrolysis reaction mechanisms from the literature and steam gasification/reforming reactions. Steam gasification steps include steam–hydrocarbons reforming, char gasification and water gas shift reactions. Evidence of fragmentation, secondary ring opening reactions and tertiary reactions resulting in formation of gaseous hydrocarbons is supported by higher flow rates of syngas and hydrogen at high heating rates and high reactor temperatures. Increase in carbon monoxide flow rate at the expense of carbon dioxide flow rate with the increase in reactor temperature has been observed. This increase in the ratio of CO/CO 2 flow rate confirms the production of CO and CO 2 from the competing reaction routes. At 1000 °C gasification a total merging between the pyrolysis step and the char gasification step has been observed. This is attributed to acceleration of char gasification reactions and acceleration of steam–hydrocarbons reforming reactions. These hydrocarbons are the precursors to

  6. Gas-Liquid Separator design of SWRPRS in PGSFR

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung; Lee, Tae-ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    There is the Sodium-Water Reaction Pressure Relief System (SWRPRS) in PGSFR to prevent the Sodium- Water Reaction (SWR) due to the break of the steam generator tube. The piping to atmosphere includes several components such as gasliquid separator, backpressure rupture disk, and hydrogen igniter. Among these components, gas-liquid separator separates the liquid sodium which is included in gas SWR products not to react sodium and air. In this study, the size of gas-liquid separator, which is based on the hydrogen volume which is exhausted in the sodium dump tank, is determined. To determine the gas-liquid separator for the separation of gas and sodium particle dumped the SDT, Stairmand's model which has high performance among standard cyclone separator models is selected. The body diameter is determined, and other dimensions are determined due to the ratio about the body diameter. Shepherd and Lapple's model is selected as the pressure drop calculation model considering the conservation.

  7. Reaction kinetics aspect of U3O8 kernel with gas H2 on the characteristics of activation energy, reaction rate constant and O/U ratio of UO2 kernel

    International Nuclear Information System (INIS)

    Damunir

    2007-01-01

    The reaction kinetics aspect of U 3 O 8 kernel with gas H 2 on the characteristics of activation energy, reaction rate constant and O/U ratio of UO 2 kernel had been studied. U 3 O 8 kernel was reacted with gas H 2 in a reduction furnace at varied reaction time and temperature. The reaction temperature was varied at 600, 700, 750 and 850 °C with a pressure of 50 mmHg for 3 hours in gas N 2 atmosphere. The reation time was varied at 1, 2, 3 and 4 hours at a temperature of 750 °C using similar conditions. The reaction product was UO 2 kernel. The reaction kinetic aspect between U 3 O 8 and gas H 2 comprised the minimum activation energy (ΔE), the reaction rate constant and the O/U ratio of UO 2 kernel. The minimum activation energy was determined from a straight line slope of equation ln [{D b . R o {(1 - (1 - X b ) ⅓ } / (b.t.Cg)] = -3.9406 x 10 3 / T + 4.044. By multiplying with the straight line slope -3.9406 x 10 3 , the ideal gas constant (R) 1.985 cal/mol and the molarity difference of reaction coefficient 2, a minimum activation energy of 15.644 kcal/mol was obtained. The reaction rate constant was determined from first-order chemical reaction control and Arrhenius equation. The O/U ratio of UO 2 kernel was obtained using gravimetric method. The analysis result of reaction rate constant with chemical reaction control equation yielded reaction rate constants of 0.745 - 1.671 s -1 and the Arrhenius equation at temperatures of 650 - 850 °C yielded reaction rate constants of 0.637 - 2.914 s -1 . The O/U ratios of UO 2 kernel at the respective reaction rate constants were 2.013 - 2.014 and the O/U ratios at reaction time 1 - 4 hours were 2.04 - 2.011. The experiment results indicated that the minimum activation energy influenced the rate constant of first-order reaction and the O/U ratio of UO 2 kernel. The optimum condition was obtained at reaction rate constant of 1.43 s -1 , O/U ratio of UO 2 kernel of 2.01 at temperature of 750 °C and reaction time of 3

  8. An evaluation of selection criteria on primary water chemistry parameters for SMART

    International Nuclear Information System (INIS)

    Choi, B. S.; Kim, S. H.; Yun, J. H.; Bae, Y. Y.; Gee, S. G.

    2003-01-01

    The selection criteria on the primary water chemistry of SMART by comparing the chemical design features with those of the current operating PWRs is analyzed. The most essential differences in water chemistry between the PWRs and SMART reactor is characterized by the presence of boron in water. SMART is boron free reactor, and the ammonia is used as a pH reagent. In SMART reactor hydrogen gas is not added to the primary coolant, but is normally generated from the radiolysis of ammonia of the coolant passes through the core. Ammonia is added once per shift because SMART reactor has no letdown and charging system during power operation. Because of these competing processes, the concentrations of hydrogen, nitrogen and ammonia in the primary coolant are steady state concentrations, which depend on the decomposition/combination rate of ammonia. Ammonia chemistry in SMART reactor has many advantages in that no hydrogen gas injection is needed to control the dissolved oxygen in primary coolant because of spontaneous generation of hydrogen and nitrogen produced by the reaction of ammonia decomposition

  9. Development of analysis model for mid and long-term effects of sodium water reaction event in LMR

    International Nuclear Information System (INIS)

    Eoh, Jae Hyuk; Sim, Yoon Sub; Kim, Seong O; Kim, Yeon Sik; Kim, Eui Kwang; Wi, Myung Hwan

    2002-04-01

    The Sodium-Water Reaction(SWR) is important in the design consideration of a LMR steam generator. To develop the analysis code for long-term effects of SWR, investigation on the characteristics of various SWR analysis code and the assessment of an analysis model for long term effects were performed. In an event of SWR, pressure spikes of wave propagation occur at its initial stage and last for a very short time, and then bulk motion of fluid and reaction products is progressed and lasts for a long time. In a case SWR occurs, a number of hydrogen bubbles produced and sodium is entrained into the bubbles through the gas-liquid bubble interfaces by evaporation or diffusion. The partial pressure of the sodium in a hydrogen bubble is determined as a function of the bubble size, temperature, and pressure, and is rapidly decreased as its size increased. From this, it can be considered that the bulk motion in the later phase of SWR is an axial motion caused by expansion of a single-phase hydrogen gas bubble produced by a reaction in the vicinity of the leak site. Through this investigation, a preliminary simple analysis model for long-term effects of SWR was set up and sensitivity study using the system design parameters such as pressure and temperature of IHTS for KALIMER was performed. Also, a simpler analysis model using the cover gas pressure change related to the production of a hydrogen bubble in a steam generator was developed from the analyses results. These simple analysis models of the reaction site and the pressure behavior with hydrogen production can be used to develop the mid and long-term analysis code for SWR in the KALIMER steam generator design

  10. Chemical Analysis of a "Miller-Type" Complex Prebiotic Broth. Part II: Gas, Oil, Water and the Oil/Water-Interface

    Science.gov (United States)

    Scherer, Sabrina; Wollrab, Eva; Codutti, Luca; Carlomagno, Teresa; da Costa, Stefan Gomes; Volkmer, Andreas; Bronja, Amela; Schmitz, Oliver J.; Ott, Albrecht

    2017-12-01

    We have analyzed the chemical variety obtained by Miller-Urey-type experiments using nuclear magnetic resonance (NMR) spectroscopy and coherent anti-Stokes Raman scattering (CARS) spectroscopy, gas chromatography followed by mass spectrometry (GC/MS) and two-dimensional gas chromatography followed by mass spectrometry (GCxGC/MS). In the course of a running Miller-Urey-type experiment, a hydrophobic organic layer emerged besides the hydrophilic aqueous phase and the gaseous phase that were initially present. The gas phase mainly consisted of aromatic compounds and molecules containing C≡ C or C≡ N triple bonds. The hydrophilic phase contained at least a few thousands of different molecules, primarily distributed in a range of 50 and 500 Da. The hydrophobic phase is characterized by carbon-rich, oil-like compounds and their amphiphilic derivatives containing oxygen with tensioactive properties. The presence of a wide range of oxidized molecules hints to the availability of oxygen radicals. We suggest that they intervene in the formation of alkylated polyethylene glycol (PEG) in the oil/water interface. CARS spectroscopy revealed distinct vibrational molecular signatures. In particular, characteristic spectral bands for cyanide compounds were observed if the broth was prepared with electric discharges in the gaseous phase. The characteristic spectral bands were absent if discharges were released onto the water surface. NMR spectroscopy on the same set of samples independently confirmed the observation. In addition, NMR spectroscopy revealed overall high chemical variability that suggests strong non-linearities due to interdependent, sequential reaction steps.

  11. Chemical Analysis of a "Miller-Type" Complex Prebiotic Broth : Part II: Gas, Oil, Water and the Oil/Water-Interface.

    Science.gov (United States)

    Scherer, Sabrina; Wollrab, Eva; Codutti, Luca; Carlomagno, Teresa; da Costa, Stefan Gomes; Volkmer, Andreas; Bronja, Amela; Schmitz, Oliver J; Ott, Albrecht

    2017-12-01

    We have analyzed the chemical variety obtained by Miller-Urey-type experiments using nuclear magnetic resonance (NMR) spectroscopy and coherent anti-Stokes Raman scattering (CARS) spectroscopy, gas chromatography followed by mass spectrometry (GC/MS) and two-dimensional gas chromatography followed by mass spectrometry (GCxGC/MS). In the course of a running Miller-Urey-type experiment, a hydrophobic organic layer emerged besides the hydrophilic aqueous phase and the gaseous phase that were initially present. The gas phase mainly consisted of aromatic compounds and molecules containing C≡C or C≡N triple bonds. The hydrophilic phase contained at least a few thousands of different molecules, primarily distributed in a range of 50 and 500 Da. The hydrophobic phase is characterized by carbon-rich, oil-like compounds and their amphiphilic derivatives containing oxygen with tensioactive properties. The presence of a wide range of oxidized molecules hints to the availability of oxygen radicals. We suggest that they intervene in the formation of alkylated polyethylene glycol (PEG) in the oil/water interface. CARS spectroscopy revealed distinct vibrational molecular signatures. In particular, characteristic spectral bands for cyanide compounds were observed if the broth was prepared with electric discharges in the gaseous phase. The characteristic spectral bands were absent if discharges were released onto the water surface. NMR spectroscopy on the same set of samples independently confirmed the observation. In addition, NMR spectroscopy revealed overall high chemical variability that suggests strong non-linearities due to interdependent, sequential reaction steps.

  12. Gas stripping and recirculation process in heavy water separation plant

    International Nuclear Information System (INIS)

    Nazzer, D.B.; Thayer, V.R.

    1976-01-01

    Hydrogen sulfide is stripped from hot effluent, in a heavy water separation plant of the dual temperature isotope separation type, by taking liquid effluent from the hot tower before passage through the humidifier, passing the liquid through one or more throttle devices to flash-off the H 2 S gas content, and feeding the gas into an absorption tower containing incoming feed water, for recycling of the gas through the process

  13. Impact of shale gas development on regional water quality.

    Science.gov (United States)

    Vidic, R D; Brantley, S L; Vandenbossche, J M; Yoxtheimer, D; Abad, J D

    2013-05-17

    Unconventional natural gas resources offer an opportunity to access a relatively clean fossil fuel that could potentially lead to energy independence for some countries. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks, however, especially those related to regional water quality, such as gas migration, contaminant transport through induced and natural fractures, wastewater discharge, and accidental spills. We review the current understanding of environmental issues associated with unconventional gas extraction. Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help manage these water-quality risks today and in the future.

  14. Implications of small water leak reactions on sodium heated steam generator design

    Energy Technology Data Exchange (ETDEWEB)

    Smedley, J A

    1975-07-01

    Various types of sodium water reactions have been looked on as possibly causing hazard conditions in sodium heated steam generator units ranging from the very improbable boiler tube double ended guillotine fracture to the almost certain occurrence of micro-leaks. Within this range small water leaks reactions have attracted particular interest and the present paper looks at the principles of associating the reactions with detection and protection systems for Commercial Fast Reactors. A method is developed for assessing whether adequate protection has been provided against the effects of small water leak reactions in a steam generator unit. (author)

  15. Matsuda–Heck reaction with arenediazonium tosylates in water

    Directory of Open Access Journals (Sweden)

    Ksenia V. Kutonova

    2015-03-01

    Full Text Available An environmentally friendly Matsuda–Heck reaction with arenediazonium tosylates has been developed for the first time. A range of alkenes was arylated in good to quantitative yields in water. The reaction is significantly accelerated when carried out under microwave heating. The arylation of haloalkylacrylates with diazonium salts has been implemented for the first time.

  16. Investigation of transition metal-catalyzed nitrene transfer reactions in water.

    Science.gov (United States)

    Alderson, Juliet M; Corbin, Joshua R; Schomaker, Jennifer M

    2018-04-11

    Transition metal-catalyzed nitrene transfer is a powerful method for incorporating new CN bonds into relatively unfunctionalized scaffolds. In this communication, we report the first examples of site- and chemoselective CH bond amination reactions in aqueous media. The unexpected ability to employ water as the solvent in these reactions is advantageous in that it eliminates toxic solvent use and enables reactions to be run at increased concentrations with lower oxidant loadings. Using water as the reaction medium has potential to expand the scope of nitrene transfer to encompass a variety of biomolecules and highly polar substrates, as well as enable pH control over the site-selectivity of CH bond amination. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Water-assisted dehalogenation of thionyl chloride in the presence of water molecules.

    Science.gov (United States)

    Yeung, Chi Shun; Ng, Ping Leung; Guan, Xiangguo; Phillips, David Lee

    2010-04-01

    A second-order Møller-Plesset perturbation theory (MP2) and density functional theory (DFT) investigation of the dehalogenation reactions of thionyl chloride is reported, in which water molecules (up to seven) were explicitly involved in the reaction complex. The dehalogenation processes of thionyl chloride were found to be dramatically catalyzed by water molecules. The reaction rate became significantly faster as more water molecules became involved in the reaction complex. The dehalogenation processes can be reasonably simulated by the gas-phase water cluster models, which reveals that water molecules can help to solvate the thionyl chloride molecules and activate the release of the Cl(-) leaving group. The computed activation energies were used to compare the calculations to available experimental data.

  18. Produced water management - clean and safe oil and gas production

    International Nuclear Information System (INIS)

    2006-01-01

    The conference contains 22 presentations on topics within pollution sources and abatement, discharge reductions, water analysis and monitoring, water production, treatment and injection, enhanced recovery, condensate water, produced water markets, separation technologies for oil/gas/condensate and water, oil removal from solids, environmental risks of oil and gas production and environmental impacts on ecosystems and fisheries. Some oil field case histories are presented. The main focus is on the northern areas such as the North Sea, the north Atlantic Ocean and the Barents Sea, and technological aspects (tk)

  19. Produced water management - clean and safe oil and gas production

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The conference contains 22 presentations on topics within pollution sources and abatement, discharge reductions, water analysis and monitoring, water production, treatment and injection, enhanced recovery, condensate water, produced water markets, separation technologies for oil/gas/condensate and water, oil removal from solids, environmental risks of oil and gas production and environmental impacts on ecosystems and fisheries. Some oil field case histories are presented. The main focus is on the northern areas such as the North Sea, the north Atlantic Ocean and the Barents Sea, and technological aspects (tk)

  20. Decomposition of water into highly combustible hydroxyl gas used in ...

    African Journals Online (AJOL)

    The method proposed involves the decomposition of water into highly combustible hydroxyl gas via electrolysis, which is used in internal combustion engines of electrical generators for electricity generation. The by-product obtained from combustion of this gas is water vapour and oxygen to replenish the atmosphere.

  1. Some insights into formamide formation through gas-phase reactions in the interstellar medium

    International Nuclear Information System (INIS)

    Redondo, Pilar; Barrientos, Carmen; Largo, Antonio

    2014-01-01

    We study the viability of different gas-phase ion-molecule reactions that could produce precursors of formamide in the interstellar medium. We analyze different reactions between cations containing a nitrogen atom (NH 3 + , NH 4 + , NH 3 OH + , and NH 2 OH + ) and neutral molecules having one carbonyl group (H 2 CO and HCOOH). First, we report a theoretical estimation of the reaction enthalpies for the proposed processes. Second, for more favorable reactions, from a thermodynamic point of view, we perform a theoretical study of the potential energy surface. In particular, the more exothermic processes correspond to the reactions of ionized and protonated hydroxylamine with formaldehyde. In addition, a neutral-neutral reaction has also been considered. The analysis of the potential energy surfaces corresponding to these reactions shows that these processes present a net activation barrier and that they cannot be considered as a source of formamide in space.

  2. Some Insights into Formamide Formation through Gas-phase Reactions in the Interstellar Medium

    Science.gov (United States)

    Redondo, Pilar; Barrientos, Carmen; Largo, Antonio

    2014-01-01

    We study the viability of different gas-phase ion-molecule reactions that could produce precursors of formamide in the interstellar medium. We analyze different reactions between cations containing a nitrogen atom (NH_{3}^{+}, NH_{4}^{+}, NH3OH+, and NH2OH+) and neutral molecules having one carbonyl group (H2CO and HCOOH). First, we report a theoretical estimation of the reaction enthalpies for the proposed processes. Second, for more favorable reactions, from a thermodynamic point of view, we perform a theoretical study of the potential energy surface. In particular, the more exothermic processes correspond to the reactions of ionized and protonated hydroxylamine with formaldehyde. In addition, a neutral-neutral reaction has also been considered. The analysis of the potential energy surfaces corresponding to these reactions shows that these processes present a net activation barrier and that they cannot be considered as a source of formamide in space.

  3. Participation of the Halogens in Photochemical Reactions in Natural and Treated Waters

    Directory of Open Access Journals (Sweden)

    Yi Yang

    2017-10-01

    Full Text Available Halide ions are ubiquitous in natural waters and wastewaters. Halogens play an important and complex role in environmental photochemical processes and in reactions taking place during photochemical water treatment. While inert to solar wavelengths, halides can be converted into radical and non-radical reactive halogen species (RHS by sensitized photolysis and by reactions with secondary reactive oxygen species (ROS produced through sunlight-initiated reactions in water and atmospheric aerosols, such as hydroxyl radical, ozone, and nitrate radical. In photochemical advanced oxidation processes for water treatment, RHS can be generated by UV photolysis and by reactions of halides with hydroxyl radicals, sulfate radicals, ozone, and other ROS. RHS are reactive toward organic compounds, and some reactions lead to incorporation of halogen into byproducts. Recent studies indicate that halides, or the RHS derived from them, affect the concentrations of photogenerated reactive oxygen species (ROS and other reactive species; influence the photobleaching of dissolved natural organic matter (DOM; alter the rates and products of pollutant transformations; lead to covalent incorporation of halogen into small natural molecules, DOM, and pollutants; and give rise to certain halogen oxides of concern as water contaminants. The complex and colorful chemistry of halogen in waters will be summarized in detail and the implications of this chemistry for global biogeochemical cycling of halogen, contaminant fate in natural waters, and water purification technologies will be discussed.

  4. Nuclear spin relaxation due to chemical shift anisotropy of gas-phase 129Xe.

    Science.gov (United States)

    Hanni, Matti; Lantto, Perttu; Vaara, Juha

    2011-08-14

    Nuclear spin relaxation provides detailed dynamical information on molecular systems and materials. Here, first-principles modeling of the chemical shift anisotropy (CSA) relaxation time for the prototypic monoatomic (129)Xe gas is carried out, both complementing and predicting the results of NMR measurements. Our approach is based on molecular dynamics simulations combined with pre-parametrized ab initio binary nuclear shielding tensors, an "NMR force field". By using the Redfield relaxation formalism, the simulated CSA time correlation functions lead to spectral density functions that, for the first time, quantitatively determine the experimental spin-lattice relaxation times T(1). The quality requirements on both the Xe-Xe interaction potential and binary shielding tensor are investigated in the context of CSA T(1). Persistent dimers Xe(2) are found to be responsible for the CSA relaxation mechanism in the low-density limit of the gas, completely in line with the earlier experimental findings.

  5. Determination of Free Fatty Acids and Triglycerides by Gas Chromatography Using Selective Esterification Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kail, Brian W; Link, Dirk D; Morreale, Bryan D

    2012-11-01

    A method for selectively determining both free fatty acids (FFA) and triacylglycerides (TAGs) in biological oils was investigated and optimized using gas chromatography after esterification of the target species to their corresponding fatty acid methyl esters (FAMEs). The method used acid catalyzed esterification in methanolic solutions under conditions of varying severity to achieve complete conversion of more reactive FFAs while preserving the concentration of TAGs. Complete conversion of both free acids and glycerides to corresponding FAMEs was found to require more rigorous reaction conditions involving heating to 120°C for up to 2 h. Method validation was provided using gas chromatography–flame ionization detection, gas chromatography–mass spectrometry, and liquid chromatography–mass spectrometry. The method improves on existing methods because it allows the total esterified lipid to be broken down by FAMEs contributed by FFA compared to FAMEs from both FFA and TAGs. Single and mixed-component solutions of pure fatty acids and triglycerides, as well as a sesame oil sample to simulate a complex biological oil, were used to optimize the methodologies. Key parameters that were investigated included: HCl-to-oil ratio, temperature and reaction time. Pure free fatty acids were found to esterify under reasonably mild conditions (10 min at 50°C with a 2.1:1 HCl to fatty acid ratio) with 97.6 ± 2.3% recovery as FAMEs, while triglycerides were largely unaffected under these reaction conditions. The optimized protocol demonstrated that it is possible to use esterification reactions to selectively determine the free acid content, total lipid content, and hence, glyceride content in biological oils. This protocol also allows gas chromatography analysis of FAMEs as a more ideal analyte than glyceride species in their native state.

  6. Reactivity of dolomite in water-saturated supercritical carbon dioxide: Significance for carbon capture and storage and for enhanced oil and gas recovery

    International Nuclear Information System (INIS)

    Wang Xiuyu; Alvarado, Vladimir; Swoboda-Colberg, Norbert; Kaszuba, John P.

    2013-01-01

    Highlights: ► Dolomite reactivity with wet and dry supercritical CO 2 were evaluated. ► Dolomite does not react with dry CO 2 . ► H 2 O-saturated supercritical CO 2 dissolves dolomite and precipitates carbonate mineral. ► Temperature/reaction time control morphology and extent of carbonate mineralization. ► Reaction with wet CO 2 may impact trapping, caprock integrity, and CCS/EOR injectivity. - Abstract: Carbon dioxide injection in porous reservoirs is the basis for carbon capture and storage, enhanced oil and gas recovery. Injected carbon dioxide is stored at multiple scales in porous media, from the pore-level as a residual phase to large scales as macroscopic accumulations by the injection site, under the caprock and at reservoir internal capillary pressure barriers. These carbon dioxide saturation zones create regions across which the full spectrum of mutual CO 2 –H 2 O solubility may occur. Most studies assume that geochemical reaction is restricted to rocks and carbon dioxide-saturated formation waters, but this paradigm ignores injection of anhydrous carbon dioxide against brine and water-alternating-gas flooding for enhanced oil recovery. A series of laboratory experiments was performed to evaluate the reactivity of the common reservoir mineral dolomite with water-saturated supercritical carbon dioxide. Experiments were conducted at reservoir conditions (55 and 110 °C, 25 MPa) and elevated temperature (220 °C, 25 MPa) for approximately 96 and 164 h (4 and 7 days). Dolomite dissolves and new carbonate mineral precipitates by reaction with water-saturated supercritical carbon dioxide. Dolomite does not react with anhydrous supercritical carbon dioxide. Temperature and reaction time control the composition, morphology, and extent of formation of new carbonate minerals. Mineral dissolution and re-precipitation due to reaction with water-saturated carbon dioxide may affect the contact line between phases, the carbon dioxide contact angle, and the

  7. Alteration of natural "3"7Ar activity concentration in the subsurface by gas transport and water infiltration

    International Nuclear Information System (INIS)

    Guillon, Sophie; Sun, Yunwei; Purtschert, Roland; Raghoo, Lauren; Pili, Eric; Carrigan, Charles R.

    2016-01-01

    High "3"7Ar activity concentration in soil gas is proposed as a key evidence for the detection of underground nuclear explosion by the Comprehensive Nuclear Test-Ban Treaty. However, such a detection is challenged by the natural background of "3"7Ar in the subsurface, mainly due to Ca activation by cosmic rays. A better understanding and improved capability to predict "3"7Ar activity concentration in the subsurface and its spatial and temporal variability is thus required. A numerical model integrating "3"7Ar production and transport in the subsurface is developed, including variable soil water content and water infiltration at the surface. A parameterized equation for "3"7Ar production in the first 15 m below the surface is studied, taking into account the major production reactions and the moderation effect of soil water content. Using sensitivity analysis and uncertainty quantification, a realistic and comprehensive probability distribution of natural "3"7Ar activity concentrations in soil gas is proposed, including the effects of water infiltration. Site location and soil composition are identified as the parameters allowing for a most effective reduction of the possible range of "3"7Ar activity concentrations. The influence of soil water content on "3"7Ar production is shown to be negligible to first order, while "3"7Ar activity concentration in soil gas and its temporal variability appear to be strongly influenced by transient water infiltration events. These results will be used as a basis for practical CTBTO concepts of operation during an OSI. - Highlights: • "3"7Ar in the subsurface as a key evidence to detect underground nuclear explosions. • Numerical modeling of "3"7Ar production and transport in variably saturated soil. • Large uncertainty on predicting "3"7Ar activity concentration in soil gas. • Control of subsurface "3"7Ar temporal variability by water infiltration events. • Limited influence of soil water content on "3"7Ar production.

  8. Gas hydrate inhibition by perturbation of liquid water structure

    Science.gov (United States)

    Sa, Jeong-Hoon; Kwak, Gye-Hoon; Han, Kunwoo; Ahn, Docheon; Lee, Kun-Hong

    2015-06-01

    Natural gas hydrates are icy crystalline materials that contain hydrocarbons, which are the primary energy source for this civilization. The abundance of naturally occurring gas hydrates leads to a growing interest in exploitation. Despite their potential as energy resources and in industrial applications, there is insufficient understanding of hydrate kinetics, which hinders the utilization of these invaluable resources. Perturbation of liquid water structure by solutes has been proposed to be a key process in hydrate inhibition, but this hypothesis remains unproven. Here, we report the direct observation of the perturbation of the liquid water structure induced by amino acids using polarized Raman spectroscopy, and its influence on gas hydrate nucleation and growth kinetics. Amino acids with hydrophilic and/or electrically charged side chains disrupted the water structure and thus provided effective hydrate inhibition. The strong correlation between the extent of perturbation by amino acids and their inhibition performance constitutes convincing evidence for the perturbation inhibition mechanism. The present findings bring the practical applications of gas hydrates significantly closer, and provide a new perspective on the freezing and melting phenomena of naturally occurring gas hydrates.

  9. Chlorine dioxide reaction with selected amino acids in water

    International Nuclear Information System (INIS)

    Navalon, Sergio; Alvaro, Mercedes; Garcia, Hermenegildo

    2009-01-01

    Chlorine dioxide is a hypochlorite alternative disinfectant agent. In this context, we have determined the products formed in the reaction of ClO 2 with selected amino acids as model compounds that can be present in natural waters. The reaction of tryptophane, histidine and tyrosine (10 ppm each) with ClO 2 were studied at molar ratios ranging from 0.25 to 4 in the presence or absence of oxygen. It was found that in the absence of oxygen adding substoichiometric amounts of ClO 2 creates products that are structurally similar to the starting amino acids. Through a series of cascade reactions the initial product distribution gradually evolves toward simple, small carbon chain products that are far from the starting amino acid. The reaction product distribution revealed that chlorine dioxide can attack the electron-rich aromatic moieties as well as the nitrogen atom lone electron pair. Our study is relevant to gain knowledge on the reaction mechanism of ClO 2 with ubiquitous amino acids present in natural waters.

  10. Investigating Ionic Effects Applied to Water Based Organocatalysed Aldol Reactions

    Directory of Open Access Journals (Sweden)

    Joshua P. Delaney

    2011-12-01

    Full Text Available Saturated aqueous solutions of various common salts were examined for their effect on aqueous aldol reactions catalysted by a highly active C2-symmetric diprolinamide organocatalyst developed in our laboratory. With respect to the aldol reaction between cyclohexanone and 4-nitrobenzaldehyde, deionised water was always a superior medium to salt solutions though some correlation to increasing anion size and depression in enantiomeric excess could be observed. Additionally, the complete inhibition of catalyst activity observed when employing tap water could be alleviated by the inclusion of ethylenediaminetetraacetate (EDTA into the aqueous media prior to reaction initiation. Extension of these reaction conditions demonstrated that these ionic effects vary on a case-to-case basis depending on the ketone/aldehyde combination.

  11. Productions of Volatile Organic Compounds (VOCs) in Surface Waters from Reactions with Atmospheric Ozone

    Science.gov (United States)

    Hopkins, Frances; Bell, Thomas; Yang, Mingxi

    2017-04-01

    Ozone (O3) is a key atmospheric oxidant, greenhouse gas and air pollutant. In marine environments, some atmospheric ozone is lost by reactions with aqueous compounds (e.g. dissolved organic material, DOM, dimethyl sulfide, DMS, and iodide) near the sea surface. These reactions also lead to formations of volatile organic compounds (VOCs). Removal of O3 by the ocean remains a large uncertainty in global and regional chemical transport models, hampering coastal air quality forecasts. To better understand the role of the ocean in controlling O3 concentrations in the coastal marine atmosphere, we designed and implemented a series of laboratory experiments whereby ambient surface seawater was bubbled with O3-enriched, VOC-free air in a custom-made glass bubble equilibration system. Gas phase concentrations of a range of VOCs were monitored continuously over the mass range m/z 33 - 137 at the outflow of the bubble equilibrator by a proton transfer reaction - mass spectrometer (PTR-MS). Gas phase O3 was also measured at the input and output of the equilibrator to monitor the uptake due to reactions with dissolved compounds in seawater. We observed consistent productions of a variety of VOCs upon reaction with O3, notably isoprene, aldehydes, and ketones. Aqueous DMS is rapidly removed from the reactions with O3. To test the importance of dissolved organic matter precursors, we added increasing (milliliter) volumes of Emiliania huxleyi culture to the equilibrator filled with aged seawater, and observed significant linear increases in gas phase concentrations of a number of VOCs. Reactions between DOM and O3 at the sea-air interface represent a potentially significant source of VOCs in marine air and a sink of atmospheric O3.

  12. Research on waterhammer caused by a rapid gas production in the severe accident of a light water reactor

    International Nuclear Information System (INIS)

    Inasaka, Fujio; Adachi, Masaki; Shiozaki, Kohki; Aya, Izuo; Nariai, Hideki

    2004-01-01

    In the severe accident of an LWR (Light Water Reactor), it is supposed that a large quantity of gas is generated in a water pool of the containment vessel due to a water-metal reaction or a steam explosion. A rapid bubble growth, if the water mass is pushed up having a coherency in time and direction in its movement, would give a severe waterhammer to the structure. In this study, we conducted experiments using two cylindrical model containment vessels with 1.0 and 0.428 m diameters, and investigated the behavior of water mass pushed up by a growing bubble and the scale effect of this phenomenon. In addition, we also closely observed the heavier of a growing bubble. In these experiments, a rapid bubble growth was simulated by injecting high-pressure air into a water pool. It was observed that the water mass was pushed up without an air penetration until the water level reached a certain elevation. On the basis of all data, experimental correlations which gave a rise distance or velocity of the water mass with coherency were proposed and the waterhammer pressure which affected the structure was quantitatively evaluated. The applicability of the existing two-phase flow numerical analysis code, RELAP5-3D to the waterhammer phenomenon caused by a rapid gas production was also verified. (author)

  13. Universal model for water costs of gas exchange by animals and plants.

    Science.gov (United States)

    Woods, H Arthur; Smith, Jennifer N

    2010-05-04

    For terrestrial animals and plants, a fundamental cost of living is water vapor lost to the atmosphere during exchange of metabolic gases. Here, by bringing together previously developed models for specific taxa, we integrate properties common to all terrestrial gas exchangers into a universal model of water loss. The model predicts that water loss scales to gas exchange with an exponent of 1 and that the amount of water lost per unit of gas exchanged depends on several factors: the surface temperature of the respiratory system near the outside of the organism, the gas consumed (oxygen or carbon dioxide), the steepness of the gradients for gas and vapor, and the transport mode (convective or diffusive). Model predictions were largely confirmed by data on 202 species in five taxa--insects, birds, bird eggs, mammals, and plants--spanning nine orders of magnitude in rate of gas exchange. Discrepancies between model predictions and data seemed to arise from biologically interesting violations of model assumptions, which emphasizes how poorly we understand gas exchange in some taxa. The universal model provides a unified conceptual framework for analyzing exchange-associated water losses across taxa with radically different metabolic and exchange systems.

  14. Water Extraction from Coal-Fired Power Plant Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    Bruce C. Folkedahl; Greg F. Weber; Michael E. Collings

    2006-06-30

    The overall objective of this program was to develop a liquid disiccant-based flue gas dehydration process technology to reduce water consumption in coal-fired power plants. The specific objective of the program was to generate sufficient subscale test data and conceptual commercial power plant evaluations to assess process feasibility and merits for commercialization. Currently, coal-fired power plants require access to water sources outside the power plant for several aspects of their operation in addition to steam cycle condensation and process cooling needs. At the present time, there is no practiced method of extracting the usually abundant water found in the power plant stack gas. This project demonstrated the feasibility and merits of a liquid desiccant-based process that can efficiently and economically remove water vapor from the flue gas of fossil fuel-fired power plants to be recycled for in-plant use or exported for clean water conservation. After an extensive literature review, a survey of the available physical and chemical property information on desiccants in conjunction with a weighting scheme developed for this application, three desiccants were selected and tested in a bench-scale system at the Energy and Environmental Research Center (EERC). System performance at the bench scale aided in determining which desiccant was best suited for further evaluation. The results of the bench-scale tests along with further review of the available property data for each of the desiccants resulted in the selection of calcium chloride as the desiccant for testing at the pilot-scale level. Two weeks of testing utilizing natural gas in Test Series I and coal in Test Series II for production of flue gas was conducted with the liquid desiccant dehumidification system (LDDS) designed and built for this study. In general, it was found that the LDDS operated well and could be placed in an automode in which the process would operate with no operator intervention or

  15. Continuous measurement of air-water gas exchange by underwater eddy covariance

    Science.gov (United States)

    Berg, Peter; Pace, Michael L.

    2017-12-01

    Exchange of gases, such as O2, CO2, and CH4, over the air-water interface is an important component in aquatic ecosystem studies, but exchange rates are typically measured or estimated with substantial uncertainties. This diminishes the precision of common ecosystem assessments associated with gas exchanges such as primary production, respiration, and greenhouse gas emission. Here, we used the aquatic eddy covariance technique - originally developed for benthic O2 flux measurements - right below the air-water interface (˜ 4 cm) to determine gas exchange rates and coefficients. Using an acoustic Doppler velocimeter and a fast-responding dual O2-temperature sensor mounted on a floating platform the 3-D water velocity, O2 concentration, and temperature were measured at high-speed (64 Hz). By combining these data, concurrent vertical fluxes of O2 and heat across the air-water interface were derived, and gas exchange coefficients were calculated from the former. Proof-of-concept deployments at different river sites gave standard gas exchange coefficients (k600) in the range of published values. A 40 h long deployment revealed a distinct diurnal pattern in air-water exchange of O2 that was controlled largely by physical processes (e.g., diurnal variations in air temperature and associated air-water heat fluxes) and not by biological activity (primary production and respiration). This physical control of gas exchange can be prevalent in lotic systems and adds uncertainty to assessments of biological activity that are based on measured water column O2 concentration changes. For example, in the 40 h deployment, there was near-constant river flow and insignificant winds - two main drivers of lotic gas exchange - but we found gas exchange coefficients that varied by several fold. This was presumably caused by the formation and erosion of vertical temperature-density gradients in the surface water driven by the heat flux into or out of the river that affected the turbulent

  16. Continuous measurement of air–water gas exchange by underwater eddy covariance

    Directory of Open Access Journals (Sweden)

    P. Berg

    2017-12-01

    Full Text Available Exchange of gases, such as O2, CO2, and CH4, over the air–water interface is an important component in aquatic ecosystem studies, but exchange rates are typically measured or estimated with substantial uncertainties. This diminishes the precision of common ecosystem assessments associated with gas exchanges such as primary production, respiration, and greenhouse gas emission. Here, we used the aquatic eddy covariance technique – originally developed for benthic O2 flux measurements – right below the air–water interface (∼ 4 cm to determine gas exchange rates and coefficients. Using an acoustic Doppler velocimeter and a fast-responding dual O2–temperature sensor mounted on a floating platform the 3-D water velocity, O2 concentration, and temperature were measured at high-speed (64 Hz. By combining these data, concurrent vertical fluxes of O2 and heat across the air–water interface were derived, and gas exchange coefficients were calculated from the former. Proof-of-concept deployments at different river sites gave standard gas exchange coefficients (k600 in the range of published values. A 40 h long deployment revealed a distinct diurnal pattern in air–water exchange of O2 that was controlled largely by physical processes (e.g., diurnal variations in air temperature and associated air–water heat fluxes and not by biological activity (primary production and respiration. This physical control of gas exchange can be prevalent in lotic systems and adds uncertainty to assessments of biological activity that are based on measured water column O2 concentration changes. For example, in the 40 h deployment, there was near-constant river flow and insignificant winds – two main drivers of lotic gas exchange – but we found gas exchange coefficients that varied by several fold. This was presumably caused by the formation and erosion of vertical temperature–density gradients in the surface water driven by the heat flux into or

  17. Controlling Chemical Reactions in Confined Environments: Water Dissociation in MOF-74

    Directory of Open Access Journals (Sweden)

    Erika M. A. Fuentes-Fernandez

    2018-02-01

    Full Text Available The confined porous environment of metal organic frameworks (MOFs is an attractive system for studying reaction mechanisms. Compared to flat oxide surfaces, MOFs have the key advantage that they exhibit a well-defined structure and present significantly fewer challenges in experimental characterization. As an example of an important reaction, we study here the dissociation of water—which plays a critical role in biology, chemistry, and materials science—in MOFs and show how the knowledge of the structure in this confined environment allows for an unprecedented level of understanding and control. In particular, combining in-situ infrared spectroscopy and first-principles calculations, we show that the water dissociation reaction can be selectively controlled inside Zn-MOF-74 by alcohol, through both chemical and physical interactions. Methanol is observed to speed up water dissociation by 25% to 100%, depending on the alcohol partial pressure. On the other hand, co-adsorption of isopropanol reduces the speed of the water reaction, due mostly to steric interactions. In addition, we also investigate the stability of the product state after the water dissociation has occurred and find that the presence of additional water significantly stabilizes the dissociated state. Our results show that precise control of reactions within nano-porous materials is possible, opening the way for advances in fields ranging from catalysis to electrochemistry and sensors.

  18. Analysis of Halogen-Mercury Reactions in Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    Paula Buitrago; Geoffrey Silcox; Constance Senior; Brydger Van Otten

    2010-01-01

    Oxidized mercury species may be formed in combustion systems through gas-phase reactions between elemental mercury and halogens, such as chorine or bromine. This study examines how bromine species affect mercury oxidation in the gas phase and examines the effects of mixtures of bromine and chlorine on extents of oxidation. Experiments were conducted in a bench-scale, laminar flow, methane-fired (300 W), quartz-lined reactor in which gas composition (HCl, HBr, NO{sub x}, SO{sub 2}) and temperature profile were varied. In the experiments, the post-combustion gases were quenched from flame temperatures to about 350 C, and then speciated mercury was measured using a wet conditioning system and continuous emissions monitor (CEM). Supporting kinetic calculations were performed and compared with measured levels of oxidation. A significant portion of this report is devoted to sample conditioning as part of the mercury analysis system. In combustion systems with significant amounts of Br{sub 2} in the flue gas, the impinger solutions used to speciate mercury may be biased and care must be taken in interpreting mercury oxidation results. The stannous chloride solution used in the CEM conditioning system to convert all mercury to total mercury did not provide complete conversion of oxidized mercury to elemental, when bromine was added to the combustion system, resulting in a low bias for the total mercury measurement. The use of a hydroxylamine hydrochloride and sodium hydroxide solution instead of stannous chloride showed a significant improvement in the measurement of total mercury. Bromine was shown to be much more effective in the post-flame, homogeneous oxidation of mercury than chlorine, on an equivalent molar basis. Addition of NO to the flame (up to 400 ppmv) had no impact on mercury oxidation by chlorine or bromine. Addition of SO{sub 2} had no effect on mercury oxidation by chlorine at SO{sub 2} concentrations below about 400 ppmv; some increase in mercury oxidation

  19. Some insights into formamide formation through gas-phase reactions in the interstellar medium

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Pilar; Barrientos, Carmen; Largo, Antonio, E-mail: predondo@qf.uva.es [Computational Chemistry Group, Departamento de Química Física, Facultad de Ciencias, Universidad de Valladolid, E-47011 Valladolid (Spain)

    2014-01-10

    We study the viability of different gas-phase ion-molecule reactions that could produce precursors of formamide in the interstellar medium. We analyze different reactions between cations containing a nitrogen atom (NH{sub 3}{sup +}, NH{sub 4}{sup +}, NH{sub 3}OH{sup +}, and NH{sub 2}OH{sup +}) and neutral molecules having one carbonyl group (H{sub 2}CO and HCOOH). First, we report a theoretical estimation of the reaction enthalpies for the proposed processes. Second, for more favorable reactions, from a thermodynamic point of view, we perform a theoretical study of the potential energy surface. In particular, the more exothermic processes correspond to the reactions of ionized and protonated hydroxylamine with formaldehyde. In addition, a neutral-neutral reaction has also been considered. The analysis of the potential energy surfaces corresponding to these reactions shows that these processes present a net activation barrier and that they cannot be considered as a source of formamide in space.

  20. Microjets and coated wheels: versatile tools for exploring collisions and reactions at gas-liquid interfaces.

    Science.gov (United States)

    Faust, Jennifer A; Nathanson, Gilbert M

    2016-07-07

    This tutorial review describes experimental aspects of two techniques for investigating collisions and reactions at the surfaces of liquids in vacuum. These gas-liquid scattering experiments provide insights into the dynamics of interfacial processes while minimizing interference from vapor-phase collisions. We begin with a historical survey and then compare attributes of the microjet and coated-wheel techniques, developed by Manfred Faubel and John Fenn, respectively, for studies of high- and low-vapor pressure liquids in vacuum. Our objective is to highlight the strengths and shortcomings of each technique and summarize lessons we have learned in using them for scattering and evaporation experiments. We conclude by describing recent microjet studies of energy transfer between O2 and liquid hydrocarbons, HCl dissociation in salty water, and super-Maxwellian helium evaporation.

  1. Measurements of water molecule density by tunable diode laser absorption spectroscopy in dielectric barrier discharges with gas-water interface

    Science.gov (United States)

    Tachibana, Kunihide; Nakamura, Toshihiro; Kawasaki, Mitsuo; Morita, Tatsuo; Umekawa, Toyofumi; Kawasaki, Masahiro

    2018-01-01

    We measured water molecule (H2O) density by tunable diode-laser absorption spectroscopy (TDLAS) for applications in dielectric barrier discharges (DBDs) with a gas-water interface. First, the effects of water temperature and presence of gas flow were tested using a Petri dish filled with water and a gas injection nozzle. Second, the TDLAS system was applied to the measurements of H2O density in two types of DBDs; one was a normal (non-inverted) type with a dielectric-covered electrode above a water-filled counter electrode and the other was an inverted type with a water-suspending mesh electrode above a dielectric-covered counter electrode. The H2O density in the normal DBD was close to the density estimated from the saturated vapor pressure, whereas the density in the inverted DBD was about half of that in the former type. The difference is attributed to the upward gas flow in the latter type, that pushes the water molecules up towards the gas-water interface.

  2. Universal model for water costs of gas exchange by animals and plants

    OpenAIRE

    Woods, H. Arthur; Smith, Jennifer N.

    2010-01-01

    For terrestrial animals and plants, a fundamental cost of living is water vapor lost to the atmosphere during exchange of metabolic gases. Here, by bringing together previously developed models for specific taxa, we integrate properties common to all terrestrial gas exchangers into a universal model of water loss. The model predicts that water loss scales to gas exchange with an exponent of 1 and that the amount of water lost per unit of gas exchanged depends on several factors: the surface t...

  3. Gas-Phase Thermal Tautomerization of Imidazole-Acetic Acid: Theoretical and Computational Investigations

    Directory of Open Access Journals (Sweden)

    Saadullah G. Aziz

    2015-11-01

    Full Text Available The gas-phase thermal tautomerization reaction between imidazole-4-acetic (I and imidazole-5-acetic (II acids was monitored using the traditional hybrid functional (B3LYP and the long-range corrected functionals (CAM-B3LYP and ωB97XD with 6-311++G** and aug-cc-pvdz basis sets. The roles of the long-range and dispersion corrections on their geometrical parameters, thermodynamic functions, kinetics, dipole moments, Highest Occupied Molecular Orbital–Lowest Unoccupied Molecular Orbital (HOMO–LUMO energy gaps and total hyperpolarizability were investigated. All tested levels of theory predicted the preference of I over II by 0.750–0.877 kcal/mol. The origin of predilection of I is assigned to the H-bonding interaction (nN8→σ*O14–H15. This interaction stabilized I by 15.07 kcal/mol. The gas-phase interconversion between the two tautomers assumed a 1,2-proton shift mechanism, with two transition states (TS, TS1 and TS2, having energy barriers of 47.67–49.92 and 49.55–52.69 kcal/mol, respectively, and an sp3-type intermediate. A water-assisted 1,3-proton shift route brought the barrier height down to less than 20 kcal/mol in gas-phase and less than 12 kcal/mol in solution. The relatively high values of total hyperpolarizability of I compared to II were interpreted and discussed.

  4. Hydrogen enrichment and separation from synthesis gas by the use of a membrane reactor

    International Nuclear Information System (INIS)

    Sanchez, J.M.; Barreiro, M.M.; Marono, M.

    2011-01-01

    One of the objectives of the CHRISGAS project was to study innovative gas separation and gas upgrading systems that have not been developed sufficiently yet to be tested at a demonstration scale within the time frame of the project, but which show some attractive merits and features for further development. In this framework CIEMAT studied, at bench scale, hydrogen enrichment and separation from syngas by the use of membranes and membrane catalytic reactors. In this paper results about hydrogen separation from synthesis gas by means of selective membranes are presented. Studies dealt with the evaluation of permeation and selectivity to hydrogen of prepared and pre-commercial Pd-based membranes. Whereas prepared membranes turned out to be non-selective, due to discontinuities of the palladium layer, studies conducted with the pre-commercial membrane showed that by means of a membrane reactor it is possible to completely separate hydrogen from the other gas components and produce pure hydrogen as a permeate stream, even in the case of complex reaction system (H 2 /CO/CO 2 /H 2 O) under WGS conditions gas mixtures. The advantages of using a water-gas shift membrane reactor (MR) over a traditional fixed bed reactor (TR) have also been studied. The experimental device included the pre-commercial Pd-based membrane and a commercial high temperature Fe-Cr-based, WGS catalyst, which was packed in the annulus between the membrane and the reactor outer shell. Results show that in the MR concept, removal of H 2 from the reaction side has a positive effect on WGS reaction, reaching higher CO conversion than in a traditional packed bed reactor at a given temperature. On increasing pressure on the reaction side permeation is enhanced and hence carbon monoxide conversion increases. -- Highlights: → H 2 enrichment and separation using a bench-scale membrane reactor MR is studied. → Permeation and selectivity to H 2 of Pd-based membranes was determined. → Complete separation

  5. Corrosion of Steels in the Vicinity of a Sodium-Water Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Davies, R. A.; Bray, J. A.; Lyons, J. M. [U.K. Atomic Energy Authority, Dounreay Experimental Reactor Establishment, Thurso, Caithness (United Kingdom)

    1967-06-15

    Rapid corrosion of steels in the vicinity of a sodium-water reaction could lead to a major reaction in a sodium-water heat exchanger. An investigation of the magnitude of the corrosion problem has been carried out under conditions simulating both a small water leak and a full size pipe burst, and further tube failures have been obtained. These experiments were carried out on a sodium rig which could accommodate simple full-scale models of sections of heat exchanger, and up to 70 lb of water was injected into 700 lb of sodium in 9.0s. The corrosion phenomena have also been investigated on a small scale under more controllable conditions by pumping water at normal pressures into a pot of sodium. With a flow-rate of 1 ml/min corrosion rates in excess of 0.005 in./min have been obtained. The effect of various parameters on the corrosion rate has been studied, and a comparison has been made of the corrosion rates obtained with a variety of steels. The corrosion appears to be a direct result of conditions during the reaction, and the appearance of the specimen and pattern of damage suggests that the main effect is concentrated where the sodium water reaction front impinges on the metal surface. The corrosion rates are very much lower with stainless steel and nickel alloys than with ferritic materials, and suggest that the phenomena are associated with the formation of (Na{sub 2}O){sub 2}FeO. Iron powder has also been observed in the vicinity of the reaction which would suggest that this is reduced at a later stage, either as a result of the hydrogen produced during reaction, or by thermal cycling. (author)

  6. Systematic Search for Chemical Reactions in Gas Phase Contributing to Methanol Formation in Interstellar Space.

    Science.gov (United States)

    Gamez-Garcia, Victoria G; Galano, Annia

    2017-10-05

    A massive search for chemical routes leading to methanol formation in gas phase has been conducted using computational chemistry, at the CBS-QB3 level of theory. The calculations were performed at five different temperatures (100, 80, 50, 20, and 10 K) and at three pressures (0.1, 0.01, and 0.001 atm) for each temperature. The search was focused on identifying reactions with the necessary features to be viable in the interstellar medium (ISM). A searching strategy was applied to that purpose, which allowed to reduce an initial set of 678 possible reactions to a subset of 11 chemical routes that are recommended, for the first time, as potential candidates for contributing to methanol formation in the gas phase of the ISM. They are all barrier-less, and thus they are expected to take place at collision rates. Hopefully, including these reactions in the currently available models, for the gas-phase methanol formation in the ISM, would help improving the predicted fractional abundance of this molecule in dark clouds. Further investigations, especially those dealing with grain chemistry and electronic excited states, would be crucial to get a complete picture of the methanol formation in the ISM.

  7. Investigation of the CH3Cl + CN(-) reaction in water: Multilevel quantum mechanics/molecular mechanics study.

    Science.gov (United States)

    Xu, Yulong; Zhang, Jingxue; Wang, Dunyou

    2015-06-28

    The CH3Cl + CN(-) reaction in water was studied using a multilevel quantum mechanics/molecular mechanics (MM) method with the multilevels, electrostatic potential, density functional theory (DFT) and coupled-cluster single double triple (CCSD(T)), for the solute region. The detailed, back-side attack SN2 reaction mechanism was mapped along the reaction pathway. The potentials of mean force were calculated under both the DFT and CCSD(T) levels for the reaction region. The CCSD(T)/MM level of theory presents a free energy activation barrier height at 20.3 kcal/mol, which agrees very well with the experiment value at 21.6 kcal/mol. The results show that the aqueous solution has a dominant role in shaping the potential of mean force. The solvation effect and the polarization effect together increase the activation barrier height by ∼11.4 kcal/mol: the solvation effect plays a major role by providing about 75% of the contribution, while polarization effect only contributes 25% to the activation barrier height. Our calculated potential of mean force under the CCSD(T)/MM also has a good agreement with the one estimated using data from previous gas-phase studies.

  8. Palladium supported on natural phosphate: Catalyst for Suzuki coupling reactions in water

    KAUST Repository

    Hassine, Ayoub

    2013-01-01

    The Suzuki-Miyaura coupling reaction is one of the most important synthetic catalytic reactions developed in the 20th century. However, the use of toxic organic solvents for this reaction still poses a scientific challenge and is an aspect of economical and ecological relevance. The use of water as a reaction medium overcomes this issue. In the present work, we described efficient Suzuki coupling reactions in water, without any phase transfer reagents and it is possible to couple challenging substrates like aryl chlorides. Notably, this protocol also works with ultra-low loading of catalyst with high turnover numbers. © 2012 Elsevier B.V.

  9. Cooling performance of helium-gas/water coolers in HENDEL

    International Nuclear Information System (INIS)

    Inagaki, Yoshiyuki; Takada, Shoji; Hayashi, Haruyoshi; Kobayashi, Toshiaki; Ohta, Yukimaru; Shimomura, Hiroaki; Miyamoto, Yoshiaki

    1994-01-01

    The helium engineering demonstration loop (HENDEL) has four helium-gas/water coolers where the cooling water flows in the tubes and helium gas on the shell side. Their cooling performance was studied using the operational data from 1982 to 1991. The heat transfer of helium gas on the shell was obtained for segmental and step-up baffle type coolers. Also, the change with operation time was investigated. The cooling performance was lowered by the graphite powder released from the graphite components for several thousand hours and thereafter recovered because the graphite powder from the components was reduced and the powder in the cooler shell was blown off during the operation. (orig.)

  10. Theoretical analysis of thermal molten metal-water reactions

    International Nuclear Information System (INIS)

    Schwalbe, W.

    1982-01-01

    In experiments with greater masses (kg-scale) two extreme cases had been oberved during the course of reaction when hot melt reacted with a vaporizable cooler liquid. Relatively mild hot interactions with slow pressure build-up and small pressure peak in the reaction volume often occurred but there were also some very violent reactions (steam explosions) where a remarkable portion of thermal energy had been transformed into mechanical energy with high pressure peaks. For the two types of reactions overall models for water as a coolant are developed here. Based on calculations and on comparisons with corresponding experiments it is shown that a relatively mild course of reaction can be explained by a fragmentation of the melt under following violent evaporation of the cooling medium. Pressures only with small reaction volumes up to the MPa range can be found in these reactions. The calculations, for example of Bird and Millington, showed a pressure maximum of 1 MPa after 170 ms of the start of the reaction; this agrees very well with the result of the experiment of 1.08 MPa. (orig./GL) [de

  11. How Sodium Chloride Salt Inhibits the Formation of CO2 Gas Hydrates.

    Science.gov (United States)

    Holzammer, Christine; Finckenstein, Agnes; Will, Stefan; Braeuer, Andreas S

    2016-03-10

    We present an experimental Raman study on how the addition of sodium chloride to CO2-hydrate-forming systems inhibits the hydrate formation thermodynamically. For this purpose, the molar enthalpy of reaction and the molar entropy of reaction for the reaction of weakly hydrogen-bonded water molecules to strongly hydrogen bonded water molecules are determined for different salinities from the Raman spectrum of the water-stretching vibration. Simultaneously, the influence of the salinity on the solubility of CO2 in the liquid water-rich phase right before the start of hydrate formation is analyzed. The results demonstrate that various mechanisms contribute to the inhibition of gas hydrate formation. For the highest salt concentration of 20 wt % investigated, the temperature of gas hydrate formation is lowered by 12 K. For this concentration the molar enthalpy and entropy of reaction become smaller by 50 and 20%, respectively. Concurrently, the solubility of carbon dioxide is reduced by 70%. These results are compared with data in literature for systems of sodium chloride in water (without carbon dioxide).

  12. Raney copper catalysts for the water-gas shift reaction: I. Preparation, activity and stability

    CSIR Research Space (South Africa)

    Mellor, JR

    1997-12-23

    Full Text Available , T Haltchev, V Kafedjiiski, B. Kunev, M. Kalchev, I. Orizarski, D. Shopov, Proceedings ofthe Sixth International Symposium, Heterogeneous Catalysis, Part 1, Sofia, 1987, p. 235. \\[18\\] W.L. Marsden, M.S. Wainwright, J.B. Friedrich, Ind. Eng. Chem, Prod... and Testing of Catalysts, Academic Press, New York, 1985. \\[33\\] J.M. Thomas, J.W. Thomas, Introduction to the Principles of Heterogeneous Catalysis, Academic Press, New York, 1975, p. 16. \\[34\\] A.D. Tomsett, H.E. Curry-Hyde, M.S. Wainwright. D.J. Young...

  13. Comparison of microbial community shifts in two parallel multi-step drinking water treatment processes.

    Science.gov (United States)

    Xu, Jiajiong; Tang, Wei; Ma, Jun; Wang, Hong

    2017-07-01

    Drinking water treatment processes remove undesirable chemicals and microorganisms from source water, which is vital to public health protection. The purpose of this study was to investigate the effects of treatment processes and configuration on the microbiome by comparing microbial community shifts in two series of different treatment processes operated in parallel within a full-scale drinking water treatment plant (DWTP) in Southeast China. Illumina sequencing of 16S rRNA genes of water samples demonstrated little effect of coagulation/sedimentation and pre-oxidation steps on bacterial communities, in contrast to dramatic and concurrent microbial community shifts during ozonation, granular activated carbon treatment, sand filtration, and disinfection for both series. A large number of unique operational taxonomic units (OTUs) at these four treatment steps further illustrated their strong shaping power towards the drinking water microbial communities. Interestingly, multidimensional scaling analysis revealed tight clustering of biofilm samples collected from different treatment steps, with Nitrospira, the nitrite-oxidizing bacteria, noted at higher relative abundances in biofilm compared to water samples. Overall, this study provides a snapshot of step-to-step microbial evolvement in multi-step drinking water treatment systems, and the results provide insight to control and manipulation of the drinking water microbiome via optimization of DWTP design and operation.

  14. Mass transfer with complex chemical reactions in gas-liquid systems: two-step reversible reactions with unit stoichiometric and kinetic orders

    NARCIS (Netherlands)

    Vas bhat, R.D.; Kuipers, J.A.M.; Versteeg, Geert

    2000-01-01

    An absorption model to study gas¿liquid mass transfer accompanied by reversible two-step reactions in the liquid phase has been presented. This model has been used to determine mass transfer rates, enhancement factors and concentration profiles over a wide range of process conditions. Although

  15. Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats

    DEFF Research Database (Denmark)

    Hyldegaard, Ole; Kerem, Dikla; Melamed, Y

    2011-01-01

    Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing....... We visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose, spinal white matter, skeletal muscle or tail tendon. Bubbles were observed during isobaric breathing-gas shifts from air to normoxic (80:20) heliox mixture...... breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent...

  16. Biological hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Benemann, J.R. [Univ. of California, Berkeley, CA (United States)

    1995-11-01

    Biological hydrogen production can be accomplished by either thermochemical (gasification) conversion of woody biomass and agricultural residues or by microbiological processes that yield hydrogen gas from organic wastes or water. Biomass gasification is a well established technology; however, the synthesis gas produced, a mixture of CO and H{sub 2}, requires a shift reaction to convert the CO to H{sub 2}. Microbiological processes can carry out this reaction more efficiently than conventional catalysts, and may be more appropriate for the relatively small-scale of biomass gasification processes. Development of a microbial shift reaction may be a near-term practical application of microbial hydrogen production.

  17. Increase in gas output by active modification of the water pressure regime

    Energy Technology Data Exchange (ETDEWEB)

    Zakirov, S N; Gordon, V Y; Kondrat, R M; Kravtsov, N A; Somov, B Y

    1981-01-01

    Based on gas-hydrodynamic calculations made on a planar model formation, two variants of formation working are examined. In the first variant, the modern ideology of working gas fields with a water pressure regime are simulated. In the second variant, working of the formation is modeled according to the suggested ideology of active modification of the water-pressure regime by operating the flooded gas wells. The calculations made indicate the efficiency of active modification of the water pressure regime from the viewpoint of controlling the fund of E wells, and most important, maximizing the final coefficient of gas bed output.

  18. Session 4: Test of a reactor for water-gas-shift reaction on a 3 kW{sub el.} scale at direct combination with auto-thermal reforming

    Energy Technology Data Exchange (ETDEWEB)

    Pasel, J.; Cremer, P.; Peters, R.; Stolten, D. [Forschungszentrum Julich GmbH, Institute for Materials and Processes in Energy Systems (IWV 3), Julich (Germany)

    2004-07-01

    The goal of the work described in this paper was to test a reactor for WGS reaction on a larger scale of approx. 3 kW{sub el.} and to demonstrate a successful direct combination of two important components of fuel processing, i.e. a combination of ATR with WGS reaction. The value for the electric power of 3 kW{sub el.} fulfils quite well the demands of a technical application of a fuel cell system if e.g. a so-called Auxiliary Power Unit (APU) is considered. An APU can be used in passenger cars, heavy duty vehicles, ships and air planes. (authors)

  19. Energy Demodulation Algorithm for Flow Velocity Measurement of Oil-Gas-Water Three-Phase Flow

    Directory of Open Access Journals (Sweden)

    Yingwei Li

    2014-01-01

    Full Text Available Flow velocity measurement was an important research of oil-gas-water three-phase flow parameter measurements. In order to satisfy the increasing demands for flow detection technology, the paper presented a gas-liquid phase flow velocity measurement method which was based on energy demodulation algorithm combing with time delay estimation technology. First, a gas-liquid phase separation method of oil-gas-water three-phase flow based on energy demodulation algorithm and blind signal separation technology was proposed. The separation of oil-gas-water three-phase signals which were sampled by conductance sensor performed well, so the gas-phase signal and the liquid-phase signal were obtained. Second, we used the time delay estimation technology to get the delay time of gas-phase signals and liquid-phase signals, respectively, and the gas-phase velocity and the liquid-phase velocity were derived. At last, the experiment was performed at oil-gas-water three-phase flow loop, and the results indicated that the measurement errors met the need of velocity measurement. So it provided a feasible method for gas-liquid phase velocity measurement of the oil-gas-water three-phase flow.

  20. MHD/gas turbine systems designed for low cooling water requirements

    International Nuclear Information System (INIS)

    Annen, K.D.; Eustis, R.H.

    1983-01-01

    The MHD/gas turbine combined-cycle system has been designed specifically for applications where the availability of cooling water is very limited. The base case systems which were studied consist of a coal-fired MHD plant with an air turbine bottoming plant and require no cooling water. In addition to the base case systems, systems were considered which included the addition of a vapor cycle bottoming plant to improve the thermal efficiency. These systems require a small amount of cooling water. The results show that the MHD/gas turbine systems have very good thermal and economic performances. The base case I MHD/gas turbine system (782 MW /SUB e/ ) requires no cooling water, has a heat rate which is 13% higher, and a cost of electricity which is only 7% higher than a comparable MHD/steam system (878 MW /SUB e/ ) having a cooling tower heat load of 720 MW. The case I vapor cycle bottomed systems have thermal and economic performances which approach and even exceed those of the MHD/steam system, while having substantially lower cooling water requirements. Performances of a second-generation MHD/gas turbine system and an oxygen-enriched, early commercial system are also evaluated. An analysis of nitric oxide emissions shows compliance with emission standards

  1. Influence of surfactants on gas-hydrate formation' kinetics in water-oil emulsion

    Science.gov (United States)

    Zemenkov, Yu D.; Shirshova, A. V.; Arinstein, E. A.; Shuvaev, A. N.

    2018-05-01

    The kinetics of gas hydrate formation of propane in a water-oil emulsion is experimentally studied when three types of surfactants (SAA (surface acting agent)) - anionic type emulsifiers - are added to the aqueous phase. It is shown that all three types of surfactants decelerate the growth of the gas-hydrate in the emulsion and can be considered as anti-agglutinating and kinetic low-dose inhibitors. The most effective inhibitor of hydrate formation in water-oil emulsion of SV-102 surfactant was revealed. For comparison, experimental studies of gas-hydrate formation under the same conditions for bulk water have been carried out. It is shown that in bulk water, all the surfactants investigated act as promoters (accelerators) of hydrate formation. A qualitative explanation of the action mechanisms of emulsifiers in the process of gas-hydrate formation in water-oil emulsion is given.

  2. Evolution of weak perturbations in gas-solid suspension with chemical reaction

    Energy Technology Data Exchange (ETDEWEB)

    Sharypov, O.V. [Russian Academy of Sciences, Novosibirsk (Russian Federation). Inst. of Thermophysics; Novosibirsk State Univ. (Russian Federation); Anufriev, I.S. [Novosibirsk State Univ. (Russian Federation)

    2013-07-01

    Dynamics of weak finite-amplitude perturbations in two-phase homogeneous medium (gas + solid particles) with non-equilibrium chemical reaction in gas is studied theoretically. Non-linear model of plane perturbation evolution is substantiated. The model takes into account wave-kinetic interaction and dissipation effects, including inter-phase heat and momentum transfer. Conditions for uniform state of the system are analyzed. Non-linear equation describing evolution of plane perturbation is derived under weak dispersion and dissipation effects. The obtained results demonstrate self-organization in the homogeneous system: steady-state periodic structure arises, its period, amplitude and velocity depends on the features of the medium. The dependencies of these parameters on dissipation and chemical kinetics are analyzed.

  3. Modeling of the Process of Three-Isotope (H, D, T) Exchange Between Hydrogen Gas and Water Vapour on Pt-SDBC Catalyst over a Wide Range of Deuterium Concentration

    International Nuclear Information System (INIS)

    Fedorchenko, O.A.; Alekseev, I.A.; Tchijov, A.S.; Uborsky, V.V.

    2005-01-01

    The large scale studies of Combined Electrolysis and Catalytic Exchange (CECE) process in Petersburg Nuclear Physics Institute showed a complicated influence of various factors on the process caused by the presence of two simultaneous isotope exchange sub processes: counter-current phase exchange (between liquid water and water vapour) and co-current catalytic exchange (between hydrogen gas and water vapour). A laboratory scale set-up of glass made apparatuses was established in such a way that it allows us to study phase and catalytic exchange apart. A computer model of the set-up has been developed.The catalytic isotope exchange model formulation is presented. A collection of reversible chemical reactions is accompanied by diffusion of the gaseous reactants and reaction products in the pores of catalyst carrier. This has some interesting features that are demonstrated. Thus it was noted that the flow rates ratio (gas to vapour - λ = G/V) as well as the concentrations of reactants exert influence on the process efficiency

  4. A novel study of methane-rich gas reforming to syngas and its kinetics over semicoke catalyst.

    Science.gov (United States)

    Zhang, Guojie; Su, Aiting; Qu, Jiangwen; Du, Yannian

    2014-01-01

    A small-size gasification unit is improved through process optimization to simulate industrial United Gas Improvement Company gasification. It finds that the reaction temperature has important impacts on semicoke catalyzed methane gas mixture. The addition of water vapor can enhance the catalytic activity of reforming, which is due to the fact that addition of water vapor not only removes carbon deposit produced in the reforming and gasification reaction processes, but also participates in gasification reaction with semicoke to generate some active oxygen-containing functional groups. The active oxygen-containing functional groups provide active sites for carbon dioxide reforming of methane, promoting the reforming reaction. It also finds that the addition of different proportions of methane-rich gas can yield synthesis gas with different H2/CO ratio. The kinetics study shows that the semicoke can reduce the activation energy of the reforming reaction and promote the occurrence of the reforming reaction. The kinetics model of methane reforming under the conditions of steam gasification over semicoke is as follows: [Formula in text].

  5. Detritiation of Tritiated Effluent Gas and Water

    International Nuclear Information System (INIS)

    Ahn, Do Hee; Kim, Kwang Rag; Paek, Seung Woo; Lee, Min Soo; Yim, Sung Paal; Chung Hong Suk

    2007-06-01

    In a demonstration scale equipment for treatment of tritium in off-gas, Pt/SDBC as oxidation catalyst and Zeolite 13X as adsorbent was charged in the beds, respectively. It was confirmed from the performance test that decontamination factor of the equipment showed more than 100 under the flow rate of off-gas of 90 l/hr and at the temperature of 65 ∼ 80 .deg. C. A small scale CECE process has been developed combining LPCE catalytic column with SPE (solid polymer electrolyte) electrolysis. The catalytic column was a trickle-bed type packed with the mixture of 1 wt% Pt/SDBC catalyst and 4 mm Dixon wire-mesh ring. The experimental results of the CECE process proved that the decontamination factor of 13 ∼ 20 under the operating conditions of the water of the 4 l/day and the effluent hydrogen gas of 16.2 mol/h. A design code of CECE process also developed which will be applied the tritium industry. An experimental method for the reduction of tritiated organic waste by using catalytic oxidation was tested in a heated catalytic reactor of 0.5 wt% Pd/Al 2 O 3 . The simulated organic liquid was converted to water over 99%. A gas chromatographic column material was developed for the separation of mixed hydrogen isotopes. 17 wt% Pd-Pt on alumina showed 90% separation efficiency at 77 % yield for the separation of 29.2 % D 2 -H 2 gas mixture

  6. Detritiation of Tritiated Effluent Gas and Water

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Do Hee; Kim, Kwang Rag; Paek, Seung Woo; Lee, Min Soo; Yim, Sung Paal; Chung Hong Suk

    2007-06-15

    In a demonstration scale equipment for treatment of tritium in off-gas, Pt/SDBC as oxidation catalyst and Zeolite 13X as adsorbent was charged in the beds, respectively. It was confirmed from the performance test that decontamination factor of the equipment showed more than 100 under the flow rate of off-gas of 90 l/hr and at the temperature of 65 {approx} 80 .deg. C. A small scale CECE process has been developed combining LPCE catalytic column with SPE (solid polymer electrolyte) electrolysis. The catalytic column was a trickle-bed type packed with the mixture of 1 wt% Pt/SDBC catalyst and 4 mm Dixon wire-mesh ring. The experimental results of the CECE process proved that the decontamination factor of 13 {approx} 20 under the operating conditions of the water of the 4 l/day and the effluent hydrogen gas of 16.2 mol/h. A design code of CECE process also developed which will be applied the tritium industry. An experimental method for the reduction of tritiated organic waste by using catalytic oxidation was tested in a heated catalytic reactor of 0.5 wt% Pd/Al{sub 2}O{sub 3}. The simulated organic liquid was converted to water over 99%. A gas chromatographic column material was developed for the separation of mixed hydrogen isotopes. 17 wt% Pd-Pt on alumina showed 90% separation efficiency at 77 % yield for the separation of 29.2 % D{sub 2}-H{sub 2} gas mixture.

  7. Effect of deposition temperature of TiO2 on the piezoelectric property of PbTiO3 film grown by PbO gas phase reaction sputtering

    International Nuclear Information System (INIS)

    Kim, Jiyoon; Kim, Yunseok; Park, Moonkyu; No, Kwangsoo; Hong, Seungbum; Buehlmann, Simon; Kim, Yong Kwan

    2010-01-01

    A 17 nm thick PbTiO 3 (PTO) films were fabricated via PbO gas phase reaction with TiO 2 starting layer in a sputtering chamber. The influence of deposition temperature of TiO 2 on the piezoelectric properties of PTO thin films was investigated. The remnant piezoresponse of PTO films nonlinearly increased as a function of TiO 2 deposition temperature, which is correlated with the increase in average grain diameter of PTO film. As grain size increases, the restriction on remnant piezoresponse imposed by the grain boundary via coupling between local strain and polarization becomes less pronounced, which results in the increase in remnant piezoresponse. Furthermore, we found that the vertical shift in piezoresponse hysteresis loops is closely related to the residual stress state. A strong correlation between the negative vertical shift and the residual tensile stress reveals that residual stress on the resulting PTO film contributed to the asymmetric piezoelectric property.

  8. Japanese position paper on sodium-water reaction testing and design

    International Nuclear Information System (INIS)

    Sato, M.; Hiroi, H.; Tanabe, H.; Miyake, O.; Kuroha, M.; Hoshi, Y.

    1984-01-01

    PNC has been developing the steam generator with helically coiled heat transfer tube bundle and downcommer tubes for the prototype fast reactor Monju since 1968. To establish the safety design against the sodium-water reaction accident was one of the most important R and D items at the start of the development. PNC started the experimental study initially in the large leak region in 1970. Until now, during twelve years, the experimental studies have been performed, which covers the phenomena from a micro leak to a large one, with the use of the SWAT-1 rig, SWAT-2 loop, SWAT-3 loop, and SWAT-4 rigs. The reliable leak detection system is necessary to minimize the damage by the sodium-water reaction. Two groups of efforts have been paid for developing the detection system. One is to develop the leak detector itself, and another is to grasp the hydrogen transport behavior in the sodium in the steam generator and the secondary piping system. Four sodium loops have been used for the development. The development of computer codes has also progressed in parallel with the sodium-water reaction experiments. Three codes have been accomplished for the design tools against the sodium-water reaction. Through the efforts mentioned above, sufficient experiences were obtained for designing and operating the Monju steam generator system

  9. Impact of wastewater infrastructure upgrades on the urban water cycle: Reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection

    Science.gov (United States)

    Barber, Larry B.; Hladik, Michelle; Vajda, Alan M.; Fitzgerald, Kevin C.; Douville, Chris

    2015-01-01

    The municipal wastewater treatment facility (WWTF) infrastructure of the United States is being upgraded to expand capacity and improve treatment, which provides opportunities to assess the impact of full-scale operational changes on water quality. Many WWTFs disinfect their effluent prior to discharge using chlorine gas, which reacts with natural and synthetic organic matter to form halogenated disinfection byproducts (HDBPs). Because HDBPs are ubiquitous in chlorine-disinfected drinking water and have adverse human health implications, their concentrations are regulated in potable water supplies. Less is known about the formation and occurrence of HDBPs in disinfected WWTF effluents that are discharged to surface waters and become part of the de facto wastewater reuse cycle. This study investigated HDBPs in the urban water cycle from the stream source of the chlorinated municipal tap water that comprises the WWTF inflow, to the final WWTF effluent disinfection process before discharge back to the stream. The impact of conversion from chlorine-gas to low-pressure ultraviolet light (UV) disinfection at a full-scale (68,000 m3 d−1 design flow) WWTF on HDBP concentrations in the final effluent was assessed, as was transport and attenuation in the receiving stream. Nutrients and trace elements (boron, copper, and uranium) were used to characterize the different urban source waters, and indicated that the pre-upgrade and post-upgrade water chemistry was similar and insensitive to the disinfection process. Chlorinated tap water during the pre-upgrade and post-upgrade samplings contained 11 (mean total concentration = 2.7 μg L−1; n=5) and 10 HDBPs (mean total concentration = 4.5 μg L−1), respectively. Under chlorine-gas disinfection conditions 13 HDBPs (mean total concentration = 1.4 μg L−1) were detected in the WWTF effluent, whereas under UV disinfection conditions, only one HDBP was detected. The chlorinated WWTF effluent had greater relative

  10. Reaction of Aluminum with Water to Produce Hydrogen - 2010 Update

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Thomas, George [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2011-06-01

    A Study of Issues Related to the Use of Aluminum for On-Board Vehicular Hydrogen Storage The purpose of this White Paper is to describe and evaluate the potential of aluminum-water reactions for the production of hydrogen for on-board hydrogen-powered vehicle applications. Although the concept of reacting aluminum metal with water to produce hydrogen is not new, there have been a number of recent claims that such aluminum-water reactions might be employed to power fuel cell devices for portable applications such as emergency generators and laptop computers, and might even be considered for possible use as the hydrogen source for fuel cell-powered vehicles.

  11. Water Saturation Relations and Their Diffusion-Limited Equilibration in Gas Shale: Implications for Gas Flow in Unconventional Reservoirs

    Science.gov (United States)

    Tokunaga, Tetsu K.; Shen, Weijun; Wan, Jiamin; Kim, Yongman; Cihan, Abdullah; Zhang, Yingqi; Finsterle, Stefan

    2017-11-01

    Large volumes of water are used for hydraulic fracturing of low permeability shale reservoirs to stimulate gas production, with most of the water remaining unrecovered and distributed in a poorly understood manner within stimulated regions. Because water partitioning into shale pores controls gas release, we measured the water saturation dependence on relative humidity (rh) and capillary pressure (Pc) for imbibition (adsorption) as well as drainage (desorption) on samples of Woodford Shale. Experiments and modeling of water vapor adsorption into shale laminae at rh = 0.31 demonstrated that long times are needed to characterize equilibrium in larger (5 mm thick) pieces of shales, and yielded effective diffusion coefficients from 9 × 10-9 to 3 × 10-8 m2 s-1, similar in magnitude to the literature values for typical low porosity and low permeability rocks. Most of the experiments, conducted at 50°C on crushed shale grains in order to facilitate rapid equilibration, showed significant saturation hysteresis, and that very large Pc (˜1 MPa) are required to drain the shales. These results quantify the severity of the water blocking problem, and suggest that gas production from unconventional reservoirs is largely associated with stimulated regions that have had little or no exposure to injected water. Gravity drainage of water from fractures residing above horizontal wells reconciles gas production in the presence of largely unrecovered injected water, and is discussed in the broader context of unsaturated flow in fractures.

  12. Gas exchange rates across the sediment-water andd air-water interfaces in south San Francisco Bay

    International Nuclear Information System (INIS)

    Hartman, B.; Hammond, D.E.

    1984-01-01

    Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainity of the determinations, about 20%. The annual average of bethic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water inteface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2--6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models

  13. Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay

    Science.gov (United States)

    Hartman, Blayne; Hammond, Douglas E.

    1984-01-01

    Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models.

  14. Controlling the photochemical reaction of an azastilbene derivative in water using a water-soluble pillar[6]arene.

    Science.gov (United States)

    Xia, Danyu; Wang, Pi; Shi, Bingbing

    2017-09-20

    Photochemistry plays an important role in our lives. It has also been a common tool in the laboratory to construct complicated systems from small molecules. Supramolecular chemistry provides an opportunity to solve some of the problems in controlling photochemical reactions via non-covalent interactions. By using confining media and weak interactions between the medium and the reactant molecule, the excited state behavior of molecules has been successfully manipulated. Pillararenes, a new class of macrocyclic hosts, have rarely been used in the field of photochemical investigations, such as the controlling of photo-induced reactions. Herein, we explore a synthetic macrocyclic host, a water-soluble pillar[6]arene, as a controlling tool to manipulate the photo-induced reactions (hydration) in water. A host-guest system in water based on a water-soluble pillar[6]arene and an azastilbene derivative, (E)-4,4'-dimethyl-4,4'-diazoniastilbene diiodide, has been constructed. Then this water-soluble pillar[6]arene was successfully employed to control the photohydration of the azastilbene derivative in water as a "protective agent".

  15. Essentials of water systems design in the oil, gas, and chemical processing industries

    CERN Document Server

    Bahadori, Alireza; Boyd, Bill

    2013-01-01

    Essentials of Water Systems Design in the Oil, Gas and Chemical Processing Industries provides valuable insight for decision makers by outlining key technical considerations and requirements of four critical systems in industrial processing plants—water treatment systems, raw water and plant water systems, cooling water distribution and return systems, and fire water distribution and storage facilities. The authors identify the key technical issues and minimum requirements related to the process design and selection of various water supply systems used in the oil, gas, and chemical processing industries. This book is an ideal, multidisciplinary work for mechanical engineers, environmental scientists, and oil and gas process engineers.

  16. Contrasting dynamics of leaf potential and gas exchange during progressive drought cycles and recovery in Amorpha fruticosa and Robinia pseudoacacia.

    Science.gov (United States)

    Yan, Weiming; Zheng, Shuxia; Zhong, Yangquanwei; Shangguan, Zhouping

    2017-06-30

    Leaf gas exchange is closely associated with water relations; however, less attention has been given to this relationship over successive drought events. Dynamic changes in gas exchange and water potential in the seedlings of two woody species, Amorpha fruticosa and Robinia pseudoacacia, were monitored during recurrent drought. The pre-dawn leaf water potential declined in parallel with gas exchange in both species, and sharp declines in gas exchange occurred with decreasing water potential. A significant correlation between pre-dawn water potential and gas exchange was observed in both species and showed a right shift in R. pseudoacacia in the second drought. The results suggested that stomatal closure in early drought was mediated mainly by elevated foliar abscisic acid (ABA) in R. pseudoacacia, while a shift from ABA-regulated to leaf-water-potential-driven stomatal closure was observed in A. fruticosa. After re-watering, the pre-dawn water potential recovered quickly, whereas stomatal conductance did not fully recover from drought in R. pseudoacacia, which affected the ability to tightly control transpiration post-drought. The dynamics of recovery from drought suggest that stomatal behavior post-drought may be restricted mainly by hydraulic factors, but non-hydraulic factors may also be involved in R. pseudoacacia.

  17. Kinetics of the gas-phase tritium oxidation reaction

    International Nuclear Information System (INIS)

    Failor, R.A.

    1989-01-01

    Homogeneous gas-phase kinetics of tritium oxidation (2T 2 + O 2 →2T 2 O) have been studied with a model that accounts explicitly for radiolysis of the major species and the kinetics of the subsequent reactions of ionic, excited-state, and neutral species. Results from model calculations are given for 10 -4 -1.0 mol% T 2 in O 2 (298 K, 1 atm). As the reaction evolves three different mechanisms control T 2 O production, each with a different overall rate expression and a different order with respect to the T 2 concentration. The effects of self-radiolysis of pure T 2 on the tritium oxidation reaction were calculated. Tritium atoms, the primary product of T 2 self-radiolysis, altered the oxidation mechanism only during the first few seconds following the initiation of the T 2 -O 2 reaction. Ozone, an important intermediate in T 2 oxidation, was monitored in-situ by U.V. absorption spectroscopy for 0.01-1.0 mol% T 2 an 1 atm O 2 . The shape of the experimental ozone time profile agreed with the model predictions. As predicted, the measured initial rate of ozone production varied linearly with initial T 2 concentration ([T 2 ] 0.6 o ), but at an initial rate one-third the predicted value. The steady-state ozone concentration ([O 3 ]ss) was predicted to be dependent on [T 2 ] 0.3 o , but the measured value was [T 2 ] 0.6 o , resulting in four times higher [O 3 ]ss than predicted for a 1.0% T 2 -O 2 mixture. Adding H 2 to the T 2 -O 2 mixture, to provide insight into the differences between the radiolytic and chemical behavior of the tritium, produced a greater decrease in [O 3 ]ss than predicted. Adjusting the reaction cell surface-to-volume ratio showed implications of minor surface removal of ozone

  18. Uranium fluoride chemistry. Part 1. The gas phase reaction of uranium hexafluoride with alcohols

    International Nuclear Information System (INIS)

    Schnautz, N.G.; Venter, P.J.

    1992-01-01

    The reaction between uranium hexafluoride (UF 6 ) and simple alcohols in the gas phase was observed to proceed by way of three possible reaction pathways involving dehydration, deoxygenative fluorination, and ether formation. These reactions can best be explained by assuming that alcohols first react with UF 6 to afford the alkoxy uranium pentafluoride intermediate ROUF 5 , which reacts further to give the dehydration, deoxygenative fluorination, and ether products. In each of the above three reaction pathways, UF 6 is transformed to UOF 4 , which being as reactive toward alcohols as UF 6 , reacts further with the alcohol in question to finally afford the unreactive uranyl fluoride (UO 2 F 2 ). 6 refs., 2 tabs

  19. Isotope exchange reaction in Li2ZrO3 packed bed

    International Nuclear Information System (INIS)

    Kawamura, Y.; Enoeda, M.; Okuno, K.

    1998-01-01

    To understand the release behavior of bred tritium in a solid breeder blanket, the tritium transfer rate and tritium inventory for various mass transfer processes should be investigated. The contribution of the surface reactions (adsorption, desorption and two kinds of isotope exchange reactions) to the release process cannot be ignored. It is believed that two kinds of isotope exchange reactions (gaseous hydrogen-tritiated water and water vapor-tritiated water) occur on the surface of the solid breeder materials when hydrogen is added to the sweep gas to enhance the tritium release rate. The isotope exchange reaction study in H-D systems was carried out using a Li 2 ZrO 3 packed bed. The exchange reaction between gaseous hydrogen and water was the rate controlling step among the two kinds of exchange reactions. The reaction rate constants were quantified, and experimental equations were proposed. The equilibrium constant of the isotope exchange reaction in the H-D system was obtained from experimental data and was found to be 1.17. (orig.)

  20. Chemical modeling of irreversible reactions in nuclear waste-water-rock systems

    International Nuclear Information System (INIS)

    Wolery, T.J.

    1981-02-01

    Chemical models of aqueous geochemical systems are usually built on the concept of thermodynamic equilibrium. Though many elementary reactions in a geochemical system may be close to equilibrium, others may not be. Chemical models of aqueous fluids should take into account that many aqueous redox reactions are among the latter. The behavior of redox reactions may critically affect migration of certain radionuclides, especially the actinides. In addition, the progress of reaction in geochemical systems requires thermodynamic driving forces associated with elementary reactions not at equilibrium, which are termed irreversible reactions. Both static chemical models of fluids and dynamic models of reacting systems have been applied to a wide spectrum of problems in water-rock interactions. Potential applications in nuclear waste disposal range from problems in geochemical aspects of site evaluation to those of waste-water-rock interactions. However, much further work in the laboratory and the field will be required to develop and verify such applications of chemical modeling

  1. The coupling effect of gas-phase chemistry and surface reactions on oxygen permeation and fuel conversion in ITM reactors

    KAUST Repository

    Hong, Jongsup

    2015-08-01

    © 2015 Elsevier B.V. The effect of the coupling between heterogeneous catalytic reactions supported by an ion transport membrane (ITM) and gas-phase chemistry on fuel conversion and oxygen permeation in ITM reactors is examined. In ITM reactors, thermochemical reactions take place in the gas-phase and on the membrane surface, both of which interact with oxygen permeation. However, this coupling between gas-phase and surface chemistry has not been examined in detail. In this study, a parametric analysis using numerical simulations is conducted to investigate this coupling and its impact on fuel conversion and oxygen permeation rates. A thermochemical model that incorporates heterogeneous chemistry on the membrane surface and detailed chemical kinetics in the gas-phase is used. Results show that fuel conversion and oxygen permeation are strongly influenced by the simultaneous action of both chemistries. It is shown that the coupling somewhat suppresses the gas-phase kinetics and reduces fuel conversion, both attributed to extensive thermal energy transfer towards the membrane which conducts it to the air side and radiates to the reactor walls. The reaction pathway and products, in the form of syngas and C2 hydrocarbons, are also affected. In addition, the operating regimes of ITM reactors in which heterogeneous- or/and homogeneous-phase reactions predominantly contribute to fuel conversion and oxygen permeation are elucidated.

  2. Quantitative in situ monitoring of an elevated temperature reaction using a water-cooled mid-infrared fiber-optic probe.

    Science.gov (United States)

    Maclaurin, P; Crabb, N C; Wells, I; Worsfold, P J; Coombs, D

    1996-04-01

    A novel water-cooled mid-infrared fiber-optic probe is described which is heatable to 230 °C. The probe has chalcogenide fibers and a ZnSe internal reflection element and is compact and fully flexible, allowing access to a wide range of standard laboratory reaction vessels and fume cupboard arrangements. Performance is demonstrated via the in situ analysis of an acid-catalyzed esterification reaction in toluene at 110 °C, and the results are compared with those from a conventional extractive sampling loop flow cell arrangement. Particular emphasis is given to the quantitative interpretation of the spectroscopic data, using gas chromatographic reference data. Calibration data are presented for univariate and partial least squares models, with an emphasis on procedures for improving the quality of interpreparation calibration and prediction through the use of focused reference analysis regimes. Subset univariate procedures are presented that yield relative errors of spectroscopy combined with bias correction partial least squares procedures for the efficient in situ quantitative analysis of laboratory scale reactions.

  3. Sodium/water reactions in steam generators of liquid metal fast breeder reactors

    International Nuclear Information System (INIS)

    Hori, M.

    1980-01-01

    The status of the research and development on sodium/water reactions resulting from the leakage of water into sodium in LMFBR steam generators is reviewed. The importance of sodium/water reaction phenomena in the design and operation of steam generators is discussed. The effects of sodium/water reactions are evaluated and methods of protection against these phenomena are surveyed. The products of chemical reactions between sodium and water under steam generator conditions are H 2 , NaOH, Na 2 O and NaH. Together with the temperature rise due to the associated exothermic reaction, these reaction products cause effects such as self-wastage, single- and multi-target wastage, and rapid pressure increase, depending on the size of the leak hole or the magnitude of leak rate. As for the wastage phenomena of small leaks, the effects of various factors have been studied and experimental correlations, as well as some theoretical work, have been performed. To investigate the pressure phenomena of a large leak, large-scale tests have been conducted by various organizations, and the computer codes to analyse these phenomena have been developed and verified by experiments. In the design of steam generators, an initial failure up to a hypothetical double-ended guillotine rupture of a single heat transfer tube is widely used as the design basis leak. Protection systems for LMFBR plants consist of leak detection devices, leak termination devices, and reaction pressure relief devices. From analyses based on research and development activities, as well as from experience with leaks in steam generator test loops and reactor plants, it has been confirmed that protection systems can satisfactorily be designed to accommodate leak incidents in LMFBR plants. (author)

  4. Gas-Phase Reactions of Dimethyl Disulfide with Aliphatic Carbanions - A Mass Spectrometry and Computational Study

    Science.gov (United States)

    Franczuk, Barbara; Danikiewicz, Witold

    2018-03-01

    Ion-molecule reactions of Me2S2 with a wide range of aliphatic carbanions differing by structure and proton affinity values have been studied in the gas phase using mass spectrometry techniques and DFT calculations. The analysis of the spectra shows a variety of product ions formed via different reaction mechanisms, depending on the structure and proton affinity of the carbanion. Product ions of thiophilic reaction ( m/z 47), SN2 ( m/z 79), and E2 elimination - addition sequence of reactions ( m/z 93) can be observed. Primary products of thiophilic reaction can undergo subsequent SN2 and proton transfer reactions. Gibbs free energy profiles calculated for experimentally observed reactions using PBE0/6-311+G(2d,p) method show good agreement with experimental results. [Figure not available: see fulltext.

  5. Recovery of Water from Boiler Flue Gas Using Condensing Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Edward Levy; Harun Bilirgen; John DuPoint

    2011-03-31

    Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and gas extraction, and water contained in boiler flue gas. This report deals with development of condensing heat exchanger technology for recovering moisture from flue gas from coal-fired power plants. The report describes: (1) An expanded data base on water and acid condensation characteristics of condensing heat exchangers in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing high-moisture, low rank coals. (2) Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue gas moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. (3) Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. (4) Data on corrosion rates of candidate heat exchanger tube materials for the different regions of the heat exchanger system as functions of acid concentration and temperature. (5) Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat exchanger tube bundle. (6) Condensed flue gas water treatment needs and costs. (7) Condensing heat exchanger designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. (8) Results of cost-benefit studies of condensing heat exchangers.

  6. Recovery of Water from Boiler Flue Gas Using Condensing Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Levy, Edward; Bilirgen, Harun; DuPont, John

    2011-03-31

    Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and gas extraction, and water contained in boiler flue gas. This report deals with development of condensing heat exchanger technology for recovering moisture from flue gas from coal-fired power plants. The report describes: • An expanded data base on water and acid condensation characteristics of condensing heat exchangers in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing highmoisture, low rank coals. • Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue gas moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. • Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. • Data on corrosion rates of candidate heat exchanger tube materials for the different regions of the heat exchanger system as functions of acid concentration and temperature. • Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat exchanger tube bundle. • Condensed flue gas water treatment needs and costs. • Condensing heat exchanger designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. • Results of cost-benefit studies of condensing heat exchangers.

  7. The Effect of Rain on Air-Water Gas Exchange

    Science.gov (United States)

    Ho, David T.; Bliven, Larry F.; Wanninkhof, Rik; Schlosser, Peter

    1997-01-01

    The relationship between gas transfer velocity and rain rate was investigated at NASA's Rain-Sea Interaction Facility (RSIF) using several SF, evasion experiments. During each experiment, a water tank below the rain simulator was supersaturated with SF6, a synthetic gas, and the gas transfer velocities were calculated from the measured decrease in SF6 concentration with time. The results from experiments with IS different rain rates (7 to 10 mm/h) and 1 of 2 drop sizes (2.8 or 4.2 mm diameter) confirm a significant and systematic enhancement of air-water gas exchange by rainfall. The gas transfer velocities derived from our experiment were related to the kinetic energy flux calculated from the rain rate and drop size. The relationship obtained for mono-dropsize rain at the RSIF was extrapolated to natural rain using the kinetic energy flux of natural rain calculated from the Marshall-Palmer raindrop size distribution. Results of laboratory experiments at RSIF were compared to field observations made during a tropical rainstorm in Miami, Florida and show good agreement between laboratory and field data.

  8. Emergency management in the gas and water supply; Notfallmanagement in der Gas- und Wasserversorgung

    Energy Technology Data Exchange (ETDEWEB)

    Boy, Stephan [KKI GmbH, Kompetenzzentrum Kritische Infrastrukturen GmbH, Berlin (Germany)

    2013-06-15

    Gas and water pipes belong to the critical infrastructure in Germany. Their protection requires a holistic risk analysis, which also keep an eye on the dependence of the power supply. [German] Gas- und Wasserleitungen gehoeren zu den kritischen Infrastrukturen in Deutschland. Ihr Schutz erfordert eine ganzheitliche Risikoanalyse, die auch die Abhaengigkeit von der Stromversorgung im Blick hat.

  9. Gas-Induced Water-hammer Loads Calculation for Safety Related Systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seungchan; Yoon, Dukjoo [Korea Hydro and Nuclear Power Co., LTd, Daejeon (Korea, Republic of); Lee, Dooyong [Seoul National Univ., Seoul (Korea, Republic of)

    2013-05-15

    Of particular interest, gas accumulation can result in system pressure transient in pump discharge piping following a pump start. Consequently, this evolves into a gas-water, a water-hammer event and the accompanying force imbalances on the piping segments can be sufficient to challenge the piping supports and restraint. This paper describes an method performing to the water-hammer loads to determine the maximum loading that would occur in the piping system following the safety injection signal and to evaluate its integrity. For a given gas void volumes in the discharge piping, the result of the calculation shows the maximum loads of 18,894.2psi, which is smaller than the allowable criteria. Also, the maximum peak axial force imbalances acting on the support is 1,720lbf as above.

  10. Gas-Induced Water-hammer Loads Calculation for Safety Related Systems

    International Nuclear Information System (INIS)

    Lee, Seungchan; Yoon, Dukjoo; Lee, Dooyong

    2013-01-01

    Of particular interest, gas accumulation can result in system pressure transient in pump discharge piping following a pump start. Consequently, this evolves into a gas-water, a water-hammer event and the accompanying force imbalances on the piping segments can be sufficient to challenge the piping supports and restraint. This paper describes an method performing to the water-hammer loads to determine the maximum loading that would occur in the piping system following the safety injection signal and to evaluate its integrity. For a given gas void volumes in the discharge piping, the result of the calculation shows the maximum loads of 18,894.2psi, which is smaller than the allowable criteria. Also, the maximum peak axial force imbalances acting on the support is 1,720lbf as above

  11. Risks to Water Resources from Shale Gas Development and Hydraulic Fracturing in the United States

    Science.gov (United States)

    Vengosh, Avner; Jackson, Robert B.; Warner, Nathaniel; Darrah, Thomas H.; Kondash, Andrew

    2014-05-01

    The rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded oil and gas exploration in the USA. The rapid rate of shale gas exploration has triggered an intense public debate regarding the potential environmental and human health effects. A review of the updated literature has identified four potential risks for impacts on water resources: (1) stray gas contamination of shallow aquifers near shale gas sites; (2) contamination of surface water and shallow groundwater from spills, leaks, and disposal of inadequately treated wastewater or hydraulic fracturing fluids; (3) accumulation of toxic and radioactive residues in soil or stream sediments near disposal or spill sites; and (4) over-extraction of water resources for drilling and hydraulic fracturing that could induce water shortages and conflicts with other water users, particularly in water-scarce areas. As part of a long-term research on the potential water contamination associated with shale gas development, new geochemical and isotopic techniques have been developed for delineating the origin of gases and contaminants in water resource. In particular, multiple geochemical and isotopic (carbon isotopes in hydrocarbons, noble gas, strontium, boron, radium isotopes) tracers have been utilized to distinguish between naturally occurring dissolved gas and salts in water and contamination directly induced from shale gas drilling and hydraulic fracturing operations.

  12. CO chemistry/research trends in CO chemistry in the US

    Energy Technology Data Exchange (ETDEWEB)

    Cantacuzene, M

    1978-10-01

    Research trends in CO chemistry in the U.S. include the development of stable and selective homogeneous catalysts which would facilitate the removal of the heat of reaction and be resistant to sulfur poisoning for the methanation reaction, methanol synthesis, and Fischer-Tropsch synthesis; development of low-temperature homogeneous water gas shift catalysts; and research on the coordination chemistry and photochemical conversions of CO/sub 2/. In 1977, the National Science Foundation awarded 16 contracts for a total of $720,000 to promote the research in this field, including studies on chemisorption and heterogeneous catalysis (four contracts) and on transition metal complexes (ten contracts, of which seven are dedicated to metal clusters). Carbon monoxide-based processes, including water gas shift reactions, CO reduction to alkanes and alcohols, hydroformylation, and homogeneous carbonylation processes, recently developed in the U.S. are listed.

  13. Destruction of polyphasic systems in supercritical water reaction media

    International Nuclear Information System (INIS)

    Leybros, A.

    2009-12-01

    Spent ion exchange resins (IER) are, hence, radioactive process wastes for which there is no satisfactory industrial treatment. Supercritical water oxidation offers a viable alternative treatment to destroy the organic structure of resins by using supercritical water properties. The reactor used in Supercritical Fluids and Membranes Laboratory is a double shell stirred reactor. Total Organic Carbon reduction rates higher than 99% were obtained thanks to POSCEA2 experimental set-up when using a co-fuel, isopropyl alcohol. Influence of operating parameters was studied. A detailed reactional mechanism for cationic and anionic resins is created. For the solubilization of the particles in supercritical water, a mechanism has been created with the identified rate determining species and implemented into Fluent software through the EDC approach. Experimental temperature profiles are well represented by EDC model. Reaction rates are hence controlled by the chemical species mixing. (author)

  14. Catalytic hot gas cleaning of gasification gas

    Energy Technology Data Exchange (ETDEWEB)

    Simell, P. [VTT Energy, Espoo (Finland). Energy Production Technologies

    1997-12-31

    {sub 2}O and gasification gas. Operation conditions free of external or internal mass transfer limitations were used. Apparent first order kinetic parameters were determined for all the studied gas mixtures. In addition, for the CO{sub 2} reaction, a mechanistic model of Langmuir-Hinshelwood type was derived and tested. The best mode was based on benzene single site adsorption as the rate determining step and non-dissociable adsorption of CO{sub 2}. To be active in gasification gas carbonate rocks have to be in a calcined state. When the catalyst was carbonated and water was present, the activity of the catalysts was lost almost completely. This decline of activity closely followed the equilibrium decomposition pressure and temperature of CaCO{sub 3}. (orig.) 56 refs.

  15. Uranium Metal Reaction Behavior in Water, Sludge, and Grout Matrices

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H.; Schmidt, Andrew J.

    2009-05-27

    This report summarizes information and data on the reaction behavior of uranium metal in water, in water-saturated simulated and genuine K Basin sludge, and in grout matrices. This information and data are used to establish the technical basis for metallic uranium reaction behavior for the K Basin Sludge Treatment Project (STP). The specific objective of this report is to consolidate the various sources of information into a concise document to serve as a high-level reference and road map for customers, regulators, and interested parties outside the STP (e.g., external reviewers, other DOE sites) to clearly understand the current basis for the corrosion of uranium metal in water, sludge, and grout.

  16. Uranium Metal Reaction Behavior in Water, Sludge, and Grout Matrices

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H.; Schmidt, Andrew J.

    2008-09-25

    This report summarizes information and data on the reaction behavior of uranium metal in water, in water-saturated simulated and genuine K Basin sludge, and in grout matrices. This information and data are used to establish the technical basis for metallic uranium reaction behavior for the K Basin Sludge Treatment Project (STP). The specific objective of this report is to consolidate the various sources of information into a concise document to serve as a high-level reference and road map for customers, regulators, and interested parties outside the STP (e.g., external reviewers, other DOE sites) to clearly understand the current basis for the corrosion of uranium metal in water, sludge, and grout.

  17. Impact of wastewater infrastructure upgrades on the urban water cycle: Reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Larry B. [U.S. Geological Survey, 3215 Marine St., Boulder, CO 80303 (United States); Hladik, Michelle L. [U.S. Geological Survey, 6000 J Street Placer Hall, Sacramento, CA 95819 (United States); Vajda, Alan M. [University of Colorado, Department of Integrative Biology, CB 171, Denver, CO 80217 (United States); Fitzgerald, Kevin C. [U.S. Geological Survey, 3215 Marine St., Boulder, CO 80303 (United States); AECOM, 500 West Jefferson St., Ste. 1600, Louisville, KY 40202 (United States); Douville, Chris [City of Boulder, 4049 75th Street, Boulder, CO 80301 (United States)

    2015-10-01

    The municipal wastewater treatment facility (WWTF) infrastructure of the United States is being upgraded to expand capacity and improve treatment, which provides opportunities to assess the impact of full-scale operational changes on water quality. Many WWTFs disinfect their effluent prior to discharge using chlorine gas, which reacts with natural and synthetic organic matter to form halogenated disinfection byproducts (HDBPs). Because HDBPs are ubiquitous in chlorine-disinfected drinking water and have adverse human health implications, their concentrations are regulated in potable water supplies. Less is known about the formation and occurrence of HDBPs in disinfected WWTF effluents that are discharged to surface waters and become part of the de facto wastewater reuse cycle. This study investigated HDBPs in the urban water cycle from the stream source of the chlorinated municipal tap water that comprises the WWTF inflow, to the final WWTF effluent disinfection process before discharge back to the stream. The impact of conversion from chlorine-gas to low-pressure ultraviolet light (UV) disinfection at a full-scale (68,000 m{sup 3} d{sup −1} design flow) WWTF on HDBP concentrations in the final effluent was assessed, as was transport and attenuation in the receiving stream. Nutrients and trace elements (boron, copper, and uranium) were used to characterize the different urban source waters, and indicated that the pre-upgrade and post-upgrade water chemistry was similar and insensitive to the disinfection process. Chlorinated tap water during the pre-upgrade and post-upgrade samplings contained 11 (mean total concentration = 2.7 μg L{sup −1}; n = 5) and 10 HDBPs (mean total concentration = 4.5 μg L{sup −1}), respectively. Under chlorine-gas disinfection conditions 13 HDBPs (mean total concentration = 1.4 μg L{sup −1}) were detected in the WWTF effluent, whereas under UV disinfection conditions, only one HDBP was detected. The chlorinated WWTF effluent had

  18. Impact of wastewater infrastructure upgrades on the urban water cycle: Reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection

    International Nuclear Information System (INIS)

    Barber, Larry B.; Hladik, Michelle L.; Vajda, Alan M.; Fitzgerald, Kevin C.; Douville, Chris

    2015-01-01

    The municipal wastewater treatment facility (WWTF) infrastructure of the United States is being upgraded to expand capacity and improve treatment, which provides opportunities to assess the impact of full-scale operational changes on water quality. Many WWTFs disinfect their effluent prior to discharge using chlorine gas, which reacts with natural and synthetic organic matter to form halogenated disinfection byproducts (HDBPs). Because HDBPs are ubiquitous in chlorine-disinfected drinking water and have adverse human health implications, their concentrations are regulated in potable water supplies. Less is known about the formation and occurrence of HDBPs in disinfected WWTF effluents that are discharged to surface waters and become part of the de facto wastewater reuse cycle. This study investigated HDBPs in the urban water cycle from the stream source of the chlorinated municipal tap water that comprises the WWTF inflow, to the final WWTF effluent disinfection process before discharge back to the stream. The impact of conversion from chlorine-gas to low-pressure ultraviolet light (UV) disinfection at a full-scale (68,000 m 3 d −1 design flow) WWTF on HDBP concentrations in the final effluent was assessed, as was transport and attenuation in the receiving stream. Nutrients and trace elements (boron, copper, and uranium) were used to characterize the different urban source waters, and indicated that the pre-upgrade and post-upgrade water chemistry was similar and insensitive to the disinfection process. Chlorinated tap water during the pre-upgrade and post-upgrade samplings contained 11 (mean total concentration = 2.7 μg L −1 ; n = 5) and 10 HDBPs (mean total concentration = 4.5 μg L −1 ), respectively. Under chlorine-gas disinfection conditions 13 HDBPs (mean total concentration = 1.4 μg L −1 ) were detected in the WWTF effluent, whereas under UV disinfection conditions, only one HDBP was detected. The chlorinated WWTF effluent had greater relative

  19. Drought Resilience of Water Supplies for Shale Gas Extraction and Related Power Generation in Texas

    Science.gov (United States)

    Reedy, R. C.; Scanlon, B. R.; Nicot, J. P.; Uhlman, K.

    2014-12-01

    There is considerable concern about water availability to support energy production in Texas, particularly considering that many of the shale plays are in semiarid areas of Texas and the state experienced the most extreme drought on record in 2011. The Eagle Ford shale play provides an excellent case study. Hydraulic fracturing water use for shale gas extraction in the play totaled ~ 12 billion gallons (bgal) in 2012, representing ~7 - 10% of total water use in the 16 county play area. The dominant source of water is groundwater which is not highly vulnerable to drought from a recharge perspective because water is primarily stored in the confined portion of aquifers that were recharged thousands of years ago. Water supply drought vulnerability results primarily from increased water use for irrigation. Irrigation water use in the Eagle Ford play was 30 billion gallons higher in the 2011 drought year relative to 2010. Recent trends toward increased use of brackish groundwater for shale gas extraction in the Eagle Ford also reduce pressure on fresh water resources. Evaluating the impacts of natural gas development on water resources should consider the use of natural gas in power generation, which now represents 50% of power generation in Texas. Water consumed in extracting the natural gas required for power generation is equivalent to ~7% of the water consumed in cooling these power plants in the state. However, natural gas production from shale plays can be overall beneficial in terms of water resources in the state because natural gas combined cycle power generation decreases water consumption by ~60% relative to traditional coal, nuclear, and natural gas plants that use steam turbine generation. This reduced water consumption enhances drought resilience of power generation in the state. In addition, natural gas combined cycle plants provide peaking capacity that complements increasing renewable wind generation which has no cooling water requirement. However, water

  20. Sequential Au(I-catalyzed reaction of water with o-acetylenyl-substituted phenyldiazoacetates

    Directory of Open Access Journals (Sweden)

    Jianbo Wang

    2011-05-01

    Full Text Available The gold(I-catalyzed reaction of water with o-acetylenyl-substituted phenyldiazoacetates provides 1H-isochromene derivatives in good yields. The reaction follows a catalytic sequence of gold carbene formation/water O–H insertion/alcohol-alkyne cyclization. The gold(I complex is the only catalyst in each of these steps.

  1. 78 FR 64905 - Carriage of Conditionally Permitted Shale Gas Extraction Waste Water in Bulk

    Science.gov (United States)

    2013-10-30

    ...-ZA31 Carriage of Conditionally Permitted Shale Gas Extraction Waste Water in Bulk AGENCY: Coast Guard... availability of a proposed policy letter concerning the carriage of shale gas extraction waste water in bulk... transport shale gas extraction waste water in bulk. The policy letter also defines the information the Coast...

  2. The study on water ingress mass in the steam generator heat-exchange tube rupture accident of modular high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Wang Yan; Shi Lei; Li Fu; Zheng Yanhua

    2012-01-01

    The steam generator heat-exchange tube rupture (SGTR) accident is an important and particular accident which will result in water ingress to the primary loop of reactor. Water ingress will result in chemical reaction of graphite fuel and structure with water, which may cause overpressure due to generation of explosive gaseous in large quantity. The study on the water ingress accident is significant for the verification of the inherent characteristics of high temperature gas-cooled reactor. The previous research shows that the amount of water ingress mass is the dominant key factor on the severity of the accident consequence. The 200 MWe high temperature gas-cooled reactor (HTR-PM), which is the first modular pebble-bed high temperature gas-cooled reactor in China designed by the Institute of Nuclear and New Energy Technology of Tsinghua University, is selected to be analyzed in this paper. The different DBA accident scenarios of double-ended break of single heat-exchange tube are simulated respectively by the thermal-hydraulic analysis code RETRAN-02. The results show the water ingress mass through the broken heat-exchange tube is related to the break location. The amount of water ingress mass is affected obviously by the capacity of the emptier system. With the balance of safety and economical efficiency, the amount of water ingress mass from the secondary side of steam generator into the primary coolant loop will be reduced by increasing properly the diameter of the draining lines. (authors)

  3. Estimation of bias shifts in a steam-generator water-level controller

    International Nuclear Information System (INIS)

    Tylee, J.L.

    1983-01-01

    A method for detecting and estimating the value of sudden bias shifts in a U-tube steam-generator water-level controller is described and evaluated. Generalized likelihood ratios (GLR) are used to perform both the bias detection and bias estimation. Simulation results using a seventh-order, linear, discrete steam-generator model demonstrate the capabilities of the GLR detection/estimation approach

  4. An improved stochastic algorithm for temperature-dependent homogeneous gas phase reactions

    CERN Document Server

    Kraft, M

    2003-01-01

    We propose an improved stochastic algorithm for temperature-dependent homogeneous gas phase reactions. By combining forward and reverse reaction rates, a significant gain in computational efficiency is achieved. Two modifications of modelling the temperature dependence (with and without conservation of enthalpy) are introduced and studied quantitatively. The algorithm is tested for the combustion of n-heptane, which is a reference fuel component for internal combustion engines. The convergence of the algorithm is studied by a series of numerical experiments and the computational cost of the stochastic algorithm is compared with the DAE code DASSL. If less accuracy is needed the stochastic algorithm is faster on short simulation time intervals. The new stochastic algorithm is significantly faster than the original direct simulation algorithm in all cases considered.

  5. Contribution to the understanding of ion-gas reactions in ICP-MS collision reaction cells: application to the resolution of isobaric and polyatomic interferences

    International Nuclear Information System (INIS)

    Quemet, A.

    2012-01-01

    Inductively Coupled Plasma Mass Spectrometry (ICP-MS) emerged as the most essential technique in inorganic analytical chemistry thanks to its numerous assets, particularly its flexibility, its sensitivity and its reproducibility. As part of the elementary and isotopic analysis of irradiated fuel and transmutation target, the analyst is faced with a complex mass spectrum, due to the presence of many radionuclides. ICP-MS can not differentiate ions with the same mass, which induces isobaric and polyatomic interferences when the ions at the same mass are different chemical species. Last generations of ICP-MS have introduced collision reaction cells. It can in situ reduce these isobaric or polyatomic interferences. The cell is a multipole (quadrupole, hexapole or octupole) device filled with a collision and/or reaction gas. The gas molecules collide or possibly react with the ion beam, which eliminates or reduces interferences. Such resolution of interferences is based on the difference of chemical behaviours between the analyte and the interfering species: the choice of the gas is crucial. A better understanding of the 'ion - gas' reaction should help choosing the reacting gases. Three ICP-MS, with the different cell geometries, were used for this study: Perkin Elmer Elan DRC e (quadrupole), Thermo Fischer X serie II (hexapole) and Agilent Technologies 7700x (octupole). The effects of the cell geometry on different experimental parameters and on the resolution of the 56 Fe + / 40 Ar 16 O + polyatomic interferences were examined to measure iron at trace or ultra-trace level. This preliminary study was applied to measure iron as impurities in uranium oxide, the method was then validated with a Certified Reference Material. The reactivities of transition metals (Zr, Ru, Pd, Ag, Cd, Sn), lanthanides (La, Ce, Nd, Sm, Eu, Gd, Dy, Er and Yb) and actinides (U, Np, Pu, Am and Cm), elements of interest in the nuclear field, are studied with numerous gases (O 2 , CO, CO 2 , N 2

  6. Effect of water injection on nitric oxide emissions of a gas turbine combustor burning natural gas fuel

    Science.gov (United States)

    Marchionna, N. R.; Diehl, L. A.; Trout, A. M.

    1973-01-01

    The effect of direct water injection on the exhaust gas emissions of a turbojet combustor burning natural gas fuel was investigated. The results are compared with the results from similar tests using ASTM Jet-A fuel. Increasing water injection decreased the emissions of oxides of nitrogen (NOX) and increased the emissions of carbon monoxide and unburned hydrocarbons. The greatest percentage decrease in NOX with increasing water injection was at the lowest inlet-air temperature tested. The effect of increasing inlet-air temperature was to decrease the effect of the water injection. The reduction in NOX due to water injection was almost identical to the results obtained with Jet-A fuel. However, the emission indices of unburned hydrocarbons, carbon monoxide, and percentage nitric oxide in NOX were not.

  7. A variable reaction rate model for chlorine decay in drinking water due to the reaction with dissolved organic matter.

    Science.gov (United States)

    Hua, Pei; Vasyukova, Ekaterina; Uhl, Wolfgang

    2015-05-15

    A second order kinetic model for simulating chlorine decay in bulk water due to the reaction with dissolved organic matter (DOM) was developed. It takes into account the decreasing reactivity of dissolved organic matter using a variable reaction rate coefficient (VRRC) which decreases with an increasing conversion. The concentration of reducing species is surrogated by the maximum chlorine demand. Temperature dependency, respectively, is described by the Arrhenius-relationship. The accuracy and adequacy of the proposed model to describe chlorine decay in bulk water were evaluated and shown for very different waters and different conditions such as water mixing or rechlorination by applying statistical tests. It is thus very well suited for application in water quality modeling for distribution systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Energy balance and flow in steam generator part with sodium-water reaction

    International Nuclear Information System (INIS)

    Matal, O.

    1980-01-01

    Relations were derived for the calculation of heat liberated during the sodium water reaction in a tube failure in different parts of a steam generator. The results are graphically shown in i-T diagrams. Heat removal is described from the reaction zone to water and steam in undisturbed tubes and to the steam generator metal structure. (author)

  9. Fracture lines: will Canada's water be protected in the rush to develop shale gas?

    Energy Technology Data Exchange (ETDEWEB)

    Parfitt, Ben [Munk School of Global Affairs at the University of Toronto (Canada)

    2010-10-15

    By combining hydraulic fracking with horizontal drilling, the gas industry has been able to unlock significant amounts of natural gas trapped inside deep and densely packed shale rock. The exploitation of shale gas has been a remarkable revolution in the last decade, going from hardly any production in 2000 to 20% of the United States' gas production in 2010. This cheap and abundant resource has been referred to as a game changer by North American industries and governments. However concerns about water usage and groundwater contamination have been raised. Indeed, the shale gas industry is responsible for the contamination of about 1,000 water wells and has been criticized for its important water withdrawals. This report intends to present the effects of shale gas production on the water supplies in Canada. It reviews the state of groundwater mapping in shale rich regions and reviews regulatory frameworks to determine if they are sufficient to protect water resources.

  10. Gas-Microjet Reactive Scattering: Collisions of HCl and DCl with Cool Salty Water.

    Science.gov (United States)

    Faust, Jennifer A; Sobyra, Thomas B; Nathanson, Gilbert M

    2016-02-18

    Liquid microjets provide a powerful means to investigate reactions of gases with salty water in vacuum while minimizing gas-vapor collisions. We use this technique to explore the fate of gaseous HCl and DCl molecules impinging on 8 molal LiCl and LiBr solutions at 238 K. The experiments reveal that HCl or DCl evaporate infrequently if they become thermally accommodated at the surface of either solution. In particular, we observe minimal thermal desorption of HCl following HCl collisions and no distinct evidence for rapid, interfacial DCl→HCl exchange following DCl collisions. These results imply that surface thermal motions are not generally strong enough to propel momentarily trapped HCl or DCl back into the gas phase before they ionize and disappear into solution. Instead, only HCl and DCl molecules that scatter directly from the surface escape entry. These recoiling molecules transfer less energy upon collision to LiBr/H2O than to LiCl/H2O, reflecting the heavier mass of Br(-) than of Cl(-) in the interfacial region.

  11. A Novel Study of Methane-Rich Gas Reforming to Syngas and Its Kinetics over Semicoke Catalyst

    Directory of Open Access Journals (Sweden)

    Guojie Zhang

    2014-01-01

    Full Text Available A small-size gasification unit is improved through process optimization to simulate industrial United Gas Improvement Company gasification. It finds that the reaction temperature has important impacts on semicoke catalyzed methane gas mixture. The addition of water vapor can enhance the catalytic activity of reforming, which is due to the fact that addition of water vapor not only removes carbon deposit produced in the reforming and gasification reaction processes, but also participates in gasification reaction with semicoke to generate some active oxygen-containing functional groups. The active oxygen-containing functional groups provide active sites for carbon dioxide reforming of methane, promoting the reforming reaction. It also finds that the addition of different proportions of methane-rich gas can yield synthesis gas with different H2/CO ratio. The kinetics study shows that the semicoke can reduce the activation energy of the reforming reaction and promote the occurrence of the reforming reaction. The kinetics model of methane reforming under the conditions of steam gasification over semicoke is as follows: k-=5.02×103·pCH40.71·pH20.26·exp(−74200/RT.

  12. Enhancing gas-phase reaction in a plasma using high intensity and high power ultrasonic acoustic waves

    DEFF Research Database (Denmark)

    2010-01-01

    is absorbed into said plasma (104), and where a sound pressure level of said generated ultrasonic high intensity and high power acoustic waves (102) is at least substantially 140 dB and where an acoustic power of said generated ultrasonic high intensity and high power acoustic waves (102); is at least...... substantially 100 W. In this way, a high sound intensity and power are obtained that efficiently enhances a gas-phase reaction in the plasma, which enhances the plasma process, e.g. enabling more efficient ozone or hydrogen generation using plasma in relation to reaction speed and/or obtained concentration......This invention relates to enhancing a gas-phase reaction in a plasma comprising: creating plasma (104) by at least one plasma source (106), and wherein that the method further comprises: generating ultrasonic high intensity and high power acoustic waves (102) having a predetermined amount...

  13. The Air-Carbon-Water Synergies and Trade-Offs in China's Natural Gas Industry

    Science.gov (United States)

    Qin, Yue

    China's coal-dominated energy structure is partly responsible for its domestic air pollution, local water stress, and the global climate change. Primarily to tackle the haze issue, China has been actively promoting a nationwide coal to natural gas end-use switch. My dissertation focuses on evaluating the air quality, carbon, and water impacts and their interactions in China's natural gas industry. Chapter 2 assesses the lifecycle climate performance of China's shale gas in comparison to coal based on stage-level energy consumption and methane leakage rates. I find the mean lifecycle carbon footprint of shale gas is about 30-50% lower than that of coal under both 20 year and 100 year global warming potentials (GWP20 and GWP100). However, primarily due to large uncertainties in methane leakage, the lifecycle carbon footprint of shale gas in China could be 15-60% higher than that of coal across sectors under GWP20. Chapter 3 evaluates the air quality, human health, and the climate impacts of China's coal-based synthetic natural gas (SNG) development. Based on earlier 2020 SNG production targets, I conduct an integrated assessment to identify production technologies and end-use applications that will bring as large air quality and health benefits as possible while keeping carbon penalties as small as possible. I find that, due to inefficient and uncontrolled coal combustion in households, allocating currently available SNG to the residential sector proves to be the best SNG allocation option. Chapter 4 compares the air quality, carbon, and water impacts of China's six major gas sources under three end-use substitution scenarios, which are focused on maximizing air pollutant emission reductions, CO 2 emission reductions, and water stress index (WSI)-weighted water consumption reductions, respectively. I find striking national air-carbon/water trade-offs due to SNG, which also significantly increases water demands and carbon emissions in regions already suffering from

  14. $\\pi \\pi $ phase-shifts in the reaction $\\pi p\\rightarrow p \\pi ^{+} \\pi ^{+} \\pi ^{-} $ at 8 GeV/c and $K \\pi $ Chew-Low anlysis in the reaction $\\K ^{-}p \\rightarrow pK ^{-} \\pi ^{+} \\pi ^{-}$ at 10 GeV

    CERN Document Server

    CERN. Geneva

    1971-01-01

    $\\pi \\pi $ phase-shifts in the reaction $\\pi p\\rightarrow p \\pi ^{+} \\pi ^{+} \\pi ^{-} $ at 8 GeV/c and $K \\pi $ Chew-Low anlysis in the reaction $\\K ^{-}p \\rightarrow pK ^{-} \\pi ^{+} \\pi ^{-}$ at 10 GeV

  15. Economics of Condensing Gas Furnaces and Water Heaters Potential in Residential Single Family Homes

    OpenAIRE

    Lekov, Alex

    2010-01-01

    Residential space and water heating accounts for over 90percent of total residential primary gas consumption in the United States. Condensing space and water heating equipment are 10-30percent more energy-efficient than conventional space and water heating. Currently, condensing gas furnaces represent 40 percent of shipments and are common in the Northern U.S. market. Meanwhile, manufacturers are planning to develop condensing gas storage water heaters to qualify for Energy Star? certificati...

  16. Test facility for fast gas injections into a vessel filled with water

    International Nuclear Information System (INIS)

    Wilhelm, D.; Kirstahler, M.

    1987-11-01

    The Fast Gas Injection Facility (SGI) was set up to study the hydrodynamics during the expansion of a gas bubble into a vessel filled with water. The gas stored in a pressure vessel expands against gravity through a circular duct into a large cylindrical vessel partly with water. This report covers the description of the test facility and the data acquisition. Results of the first test series are added. (orig.) [de

  17. Changes in baseflow patterns in water-limited shale oil and gas regions: the Eagle Ford play

    Science.gov (United States)

    Arciniega, S.; Brena-Naranjo, J. A.; Hernández-Espriú, A.; Pedrozo-Acuña, A.

    2016-12-01

    Quantifying and analyzing the contribution of groundwater from shallow aquifers to rivers as baseflow is very important for water supply and riverine ecosystem health, especially in water-limited catchments. Baseflow depends on the water available (precipitation), vegetation (land use, water use), aquifer properties and water-table depth. In this context, human activities such as groundwater abstraction for multiple purposes can alter the relationship between aquifer storage and baseflow. In this study, we analyzed observed changes in baseflow patterns of 40 catchments located across the Eagle Ford shale gas/oil play (Texas) during the period 1986-2015. The Eagle Ford sedimentary formation is actually the largest shale oil producing region in the US with large production in shale gas. Intensive unconventional resources extraction in the Eagle Ford play started in 2009 and gas/oil production increased faster than in other plays, accompanied by a rise in groundwater consumption for HF purposes. Spatial and temporal impacts on baseflow at the Eagle Ford play derived from HF were assessed by means of different patterns such as baseflow hydrograph separation, flow-duration curves, empirical storage-discharge relationships and streamflow recession curve analysis. A comparison during different periods of water use for HF activities was performed: pre-development period (1986-2000); moderate period (2001-2008); and intensive period (2009-2015). The pre-development period was considered as a baseline and catchments located inside and outside the play area were separately analyzed. The results show negative changes on baseflow patterns during the intensive HF period that were not observed during the moderate period, especially in catchments located inside the play. These changes were also characterized by a decline on mean annual baseflow volume and shorter hydrograph recession times, that led to a shift in the streamflow regime in some catchments from perennial to

  18. Photocatalytic Water-Splitting Reaction from Catalytic and Kinetic Perspectives

    KAUST Repository

    Hisatomi, Takashi; Takanabe, Kazuhiro; Domen, Kazunari

    2014-01-01

    Abstract: Some particulate semiconductors loaded with nanoparticulate catalysts exhibit photocatalytic activity for the water-splitting reaction. The photocatalysis is distinct from the thermal catalysis because photocatalysis involves photophysical

  19. Shale gas operator violations in the Marcellus and what they tell us about water resource risks

    International Nuclear Information System (INIS)

    Rahm, Brian G.; Vedachalam, Sridhar; Bertoia, Lara R.; Mehta, Dhaval; Vanka, Veeravenkata Sandeep; Riha, Susan J.

    2015-01-01

    Development of shale gas entails environmental risk, particularly with respect to water resources, and stakeholders are keen to assess such risks before making development decisions. We focus on Pennsylvania, USA and the Marcellus Shale, the most productive shale play in the country. We examine compliance data recorded by the state regulatory agency in order to assess environmental risks and their trends and drivers over time. Overall, we track 3267 shale gas violations, noting that environmental violation rates increase from 2007 to 2009, remain high through 2010, and then drop in 2011 and thereafter. Violations related to spills and erosion were most commonly issued. A single change in policy resulted in a 45% decrease in environmental violation rates. Furthermore, for every 1% increase in wells drilled per inspections conducted, there was a 0.56% decrease in environmental violation rates. Similar effects were not found for administrative violations. Operator identity, price of gas, and other major policies were not significantly correlated with violation rates. In comparing conventional and shale gas extraction compliance we found that shale gas development entails more risk related to spills and solid waste management, while conventional development entails more risk associated with cementing and casing issues, and site restoration. -- Highlights: •We examine trends in violations issued to natural gas operators over 6.5 years. •Analyzed 3267 unconventional and 9784 conventional violations. •Decreased unconventional violation rates after 2011. •Decrease best explained by shifting regulatory policy and inspector productivity. •Differences in risks associated with conventional and unconventional development

  20. The reaction kinetics of lithium salt with water vapor

    International Nuclear Information System (INIS)

    Balooch, M.; Dinh, L.N.; Calef, D.F.

    2002-01-01

    The interaction of lithium salt (LiH and/or LiD) with water vapor in the partial pressure range of 10 -5 -2657 Pa has been investigated. The reaction probability of water with LiH cleaved in an ultra high vacuum environment was obtained using the modulated molecular beam technique. This probability was 0.11 and independent of LiH surface temperature, suggesting a negligible activation energy for the reaction in agreement with quantum chemical calculations. The value gradually reduced, however, to 0.007 as the surface concentration of oxygen containing product approached full coverage. As the film grew beyond a monolayer, the phase lag of hydrogen product increased from 0 deg. C to 20 deg. C and the reaction probability reduced further until it approached our detection limit (∼10 -4 ). This phase lag was attributed to a diffusion-limited process in this regime. For micrometer thick hydroxide films grown in high moisture concentration environment on LiD and LiH, the reaction probability reduced to ∼4x10 -7 and was independent of exposure time. In this regime of thick hydroxide films (LiOH and/or LiOD), microcracks generated in the films to release stress provided easier pathways for moisture to reach the interface. A modified microscope, capable of both atomic force microscopy and nanoindentation, was also employed to investigate the surface morphology of hydroxide monohydrate (LiOH · H 2 O and/or LiOD · H 2 O) grown on hydroxide at high water vapor partial pressures and the kinetics of this growth

  1. Kinetics and Mechanisms of Calcite Reactions with Saline Waters

    Energy Technology Data Exchange (ETDEWEB)

    Gorman, Brian P [Colorado School of Mines, Golden, CO (United States)

    2015-09-02

    Project Description: The general objective of the proposed research is to determine the kinetics and mechanisms of calcite reactions with saline waters over a wide range of saline water composition, pCO2, and modest ranges in T and P. This will be accomplished by studying both reaction rates and solubility from changes in solution chemistry, and making nanoscale observations of calcite precipitate surface morphology and composition at the micro-to-nano-scale to provide an understanding of controlling reaction mechanisms and pathways. The specific objectives necessary to reach the general objective are: a) determination of how pCO2, Ca2+, ionic strength and “foreign” ions influence reaction rates; and b) investigate the influence of these parameters on apparent kinetic solubility from dissolution and precipitation reactions. This information will clearly be central to the construction of reliable reaction-transport models to predict reservoir and formation response to increased CO2 in saline waters. This program was initially collaborative with John Morse at Texas A&M, however his passing shortly after the beginning of this program resulted in abbreviated research time and effort. Summary of Results: Early studies using electron microscopy and spectroscopy indicated that carbonate precipitation from natural seawater (NSW) conditions onto aragonite substrates was mediated by a surface amorphous calcium carbonate layer. It was hypothesized that this ACC layer (observed after < 5days reaction time) was responsible for the abnormal reaction kinetics and also served as a metastable seed layer for growth of epitaxial aragonite. Further studies of the ACC formation mechanism indicated a strong dependence on the Mg concentration in solution. Subsequent studies at shorter times (10 hrs) on calcite substrates and in a wide range of supersaturation conditions did not indicate any ACC layer. Instead, an epitaxial layer by layer

  2. Pervaporation applied for dewatering of reaction mixture during esterification

    Directory of Open Access Journals (Sweden)

    Krasiński Andrzej

    2016-03-01

    Full Text Available In this work the esterification of diethyl tartrate was studied. The research was focused on the enhancement of reversible reaction yield, which is accomplished by dewatering of the reaction mixture. The removal of water shifts the equilibrium towards the main product. Pervaporation was applied for this purpose, and results were compared to distillation. The advantages and limitations of both processes are discussed. The experimental part consists of dewatering of mixture after the reaction had reached the equilibrium, and was subsequently fed to the test rig equipped with a single zeolite membrane purchased from Pervatech B.V. Results show a significant conversion increase as a result of water removal by pervaporation. Compared to distillation no addition of organics is necessary to efficiently remove water above the azeotrope. Nevertheless, some limitations and issues which call for optimisation are pointed out. A simple numerical model is proposed to support design and sizing of the pervaporation system. Various modes of integrated system operation are also briefly discussed.

  3. Application of the carbon dioxide-barium hydroxide hydrate gas-solid reaction for the treatment of dilute carbon dioxide-bearing gas streams

    International Nuclear Information System (INIS)

    Haag, G.L.

    1983-09-01

    The removal of trace components from gas streams via irreversible gas-solid reactions in an area of interest to the chemical engineering profession. This research effort addresses the use of fixed beds of Ba(OH) 2 hydrate flakes for the removal of an acid gas, CO 2 , from air that contains approx. 330 ppM/sub v/ CO 2 . Areas of investigation encompassed: (1) an extensive literature review of Ba(OH) 2 hydrate chemistry, (2) microscale studies on 0.150-g samples to develop a better understanding of the reaction, (3) process studies at the macroscale level with 10.2-cm-ID fixed-bed reactors, and (4) the development of a model for predicting fixed-bed performance. Experimental studies indicated fixed beds of commercial Ba(OH) 2 .8H 2 O flakes at ambient temperatures to be capable of high CO 2 -removal efficiencies (effluent concentrations 99%), and an acceptable pressure drop (1.8 kPa/m at a superficial gas velocity of 13 cm/s). Ba(OH) 2 .8H 2 O was determined to be more reactive toward CO 2 than either Ba(OH) 2 .3H 2 O or Ba(OH) 2 .1H 2 O. A key variable in the development of this fixed-bed process was relative humidity. Operation at conditions with effluent relative humidities >60% resulted in significant recrystallization and restructuring of the flake and subsequent pressure-drop problems

  4. Gas-water-rock interactions induced by reservoir exploitation, CO2 sequestration, and other geological storage

    International Nuclear Information System (INIS)

    Lecourtier, J.

    2005-01-01

    Here is given a summary of the opening address of the IFP International Workshop: 'gas-water-rock interactions induced by reservoir exploitation, CO 2 sequestration, and other geological storage' (18-20 November 2003). 'This broad topic is of major interest to the exploitation of geological sites since gas-water-mineral interactions determine the physicochemical characteristics of these sites, the strategies to adopt to protect the environment, and finally, the operational costs. Modelling the phenomena is a prerequisite for the engineering of a geological storage, either for disposal efficiency or for risk assessment and environmental protection. During the various sessions, several papers focus on the great achievements that have been made in the last ten years in understanding and modelling the coupled reaction and transport processes occurring in geological systems, from borehole to reservoir scale. Remaining challenges such as the coupling of mechanical processes of deformation with chemical reactions, or the influence of microbiological environments on mineral reactions will also be discussed. A large part of the conference programme will address the problem of mitigating CO 2 emissions, one of the most important issues that our society must solve in the coming years. From both a technical and an economic point of view, CO 2 geological sequestration is the most realistic solution proposed by the experts today. The results of ongoing pilot operations conducted in Europe and in the United States are strongly encouraging, but geological storage will be developed on a large scale in the future only if it becomes possible to predict the long term behaviour of stored CO 2 underground. In order to reach this objective, numerous issues must be solved: - thermodynamics of CO 2 in brines; - mechanisms of CO 2 trapping inside the host rock; - geochemical modelling of CO 2 behaviour in various types of geological formations; - compatibility of CO 2 with oil-well cements

  5. An evaluation of water quality in private drinking water wells near natural gas extraction sites in the Barnett Shale formation.

    Science.gov (United States)

    Fontenot, Brian E; Hunt, Laura R; Hildenbrand, Zacariah L; Carlton, Doug D; Oka, Hyppolite; Walton, Jayme L; Hopkins, Dan; Osorio, Alexandra; Bjorndal, Bryan; Hu, Qinhong H; Schug, Kevin A

    2013-09-03

    Natural gas has become a leading source of alternative energy with the advent of techniques to economically extract gas reserves from deep shale formations. Here, we present an assessment of private well water quality in aquifers overlying the Barnett Shale formation of North Texas. We evaluated samples from 100 private drinking water wells using analytical chemistry techniques. Analyses revealed that arsenic, selenium, strontium and total dissolved solids (TDS) exceeded the Environmental Protection Agency's Drinking Water Maximum Contaminant Limit (MCL) in some samples from private water wells located within 3 km of active natural gas wells. Lower levels of arsenic, selenium, strontium, and barium were detected at reference sites outside the Barnett Shale region as well as sites within the Barnett Shale region located more than 3 km from active natural gas wells. Methanol and ethanol were also detected in 29% of samples. Samples exceeding MCL levels were randomly distributed within areas of active natural gas extraction, and the spatial patterns in our data suggest that elevated constituent levels could be due to a variety of factors including mobilization of natural constituents, hydrogeochemical changes from lowering of the water table, or industrial accidents such as faulty gas well casings.

  6. Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

    Directory of Open Access Journals (Sweden)

    M. M. Chim

    2017-12-01

    Full Text Available Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C5H8O4 droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C5 hydroxyl functionalization product (C5H8O5 and a C4 fragmentation product (C4H6O3. These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from

  7. Hot gas stripping of ammonia and carbon dioxide from simulated and actual in situ retort waters

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, C.L.

    1979-01-01

    This study proved that ammonia and carbon dioxide could be removed from retort water by hot gas stripping and that overall transfer rates were slower than for physical desorption alone. The ammonia in solution complexed with the carbonate species with the result that the CO/sub 2/ transfer rates were linked to the relatively slower desorption of NH/sub 3/ from solution. Ionic reactions in the liquid phase limited the quantity of free NH/sub 3/ and CO/sub 2/, thus decreasing the driving forces for mass transfer. The retort water exhibited foaming tendencies that affected the interfacial area which should be taken into account if a stripping tower is considered on a larger scale. Transfer unit heights were calculated for the process conditions studied and correlated such that scaleup to increased capacities is possible.

  8. Lewis acid catalysis of a Diels-Alder reaction in water

    NARCIS (Netherlands)

    Otto, S; Bertoncin, F; Engberts, JBFN

    1996-01-01

    Here we report the first detailed study of a Diels-Alder (DA) reaction that is catalyzed by Lewis acids in water. The effect of Co2+, Ni2+, Cu2+ and Zn2+ ions as Lewis acid catalysts on the rate and endo-exo selectivity of the DA reaction between the bidentate dienophiles

  9. Detailed Reaction Kinetics for CFD Modeling of Nuclear Fuel Pellet Coating for High Temperature Gas-Cooled Reactors

    International Nuclear Information System (INIS)

    Battaglia, Francine

    2008-01-01

    The research project was related to the Advanced Fuel Cycle Initiative and was in direct alignment with advancing knowledge in the area of Nuclear Fuel Development related to the use of TRISO fuels for high-temperature reactors. The importance of properly coating nuclear fuel pellets received a renewed interest for the safe production of nuclear power to help meet the energy requirements of the United States. High-temperature gas-cooled nuclear reactors use fuel in the form of coated uranium particles, and it is the coating process that was of importance to this project. The coating process requires four coating layers to retain radioactive fission products from escaping into the environment. The first layer consists of porous carbon and serves as a buffer layer to attenuate the fission and accommodate the fuel kernel swelling. The second (inner) layer is of pyrocarbon and provides protection from fission products and supports the third layer, which is silicon carbide. The final (outer) layer is also pyrocarbon and provides a bonding surface and protective barrier for the entire pellet. The coating procedures for the silicon carbide and the outer pyrocarbon layers require knowledge of the detailed kinetics of the reaction processes in the gas phase and at the surfaces where the particles interact with the reactor walls. The intent of this project was to acquire detailed information on the reaction kinetics for the chemical vapor deposition (CVD) of carbon and silicon carbine on uranium fuel pellets, including the location of transition state structures, evaluation of the associated activation energies, and the use of these activation energies in the prediction of reaction rate constants. After the detailed reaction kinetics were determined, the reactions were implemented and tested in a computational fluid dynamics model, MFIX. The intention was to find a reduced mechanism set to reduce the computational time for a simulation, while still providing accurate results

  10. Capture reactions at astrophysically relevant energies: extended gas target experiments and GEANT simulations

    CERN Document Server

    Kölle, V; Braitmayer, S E; Mohr, P J; Wilmes, S; Staudt, G; Hammer, J W; Jäger, M; Knee, H; Kunz, R; Mayer, A

    1999-01-01

    Several resonances of the capture reaction sup 2 sup 0 Ne(alpha, gamma) sup 2 sup 4 Mg were measured using an extended windowless gas target system. Detailed GEANT simulations were performed to derive the strength and the total width of the resonances from the measured yield curve. The crucial experimental parameters, which are mainly the density profile in the gas target and the efficiency of the gamma-ray detector, were analyzed by a comparison between the measured data and the corresponding simulation calculations. The excellent agreement between the experimental data and the simulations gives detailed insight into these parameters. (author)

  11. Novel silica membranes for high temperature gas separations

    KAUST Repository

    Bighane, Neha

    2011-04-01

    This article describes fabrication of novel silica membranes derived via controlled oxidative thermolysis of polydimethylsiloxane and their gas separation performance. The optimized protocol for fabrication of the silica membranes is described and pure gas separation performance in the temperature range 35-80°C is presented. It is observed that the membranes exhibit activated transport for small gas penetrants such as He, H 2 and CO 2. The membranes can withstand temperatures up to 350°C in air and may ultimately find use in H 2/CO 2 separations to improve efficiency in the water-gas shift reactor process. © 2011 Elsevier B.V.

  12. In situ water and gas injection experiments performed in the Hades Underground Research Facility

    Energy Technology Data Exchange (ETDEWEB)

    Volckaert, G.; Ortiz, L.; Put, M. [SCK-CEN, Mol (Belgium). Geological Waste Disposal Unit

    1995-12-31

    The movement of water and gas through plastic clay is an important subject in the research at SCK-CEN on the possible disposal of high level radioactive waste in the Boom clay layer at Mol. Since the construction of the Hades underground research facility in 1983, SCK-CEN has developed and installed numerous piezometers for the geohydrologic characterization and for in situ radionuclide migration experiments. In situ gas and water injection experiments have been performed at two different locations in the underground laboratory. The first location is a multi filter piezometer installed vertically at the bottom of the shaft in 1986. The second location is a three dimensional configuration of four horizontal multi piezometers installed from the gallery. This piezometer configuration was designed for the MEGAS (Modelling and Experiments on GAS migration through argillaceous rocks) project and installed in 1992. It contains 29 filters at distances between 10 m and 15 m from the gallery in the clay. Gas injection experiments show that gas breakthrough occurs at a gas overpressure of about 0.6 MPa. The breakthrough occurs by the creation of gas pathways along the direction of lowest resistance i.e. the zone of low effective stress resulting from the drilling of the borehole. The water injections performed in a filter -- not used for gas injection -- show that the flow of water is also influenced by the mechanical stress conditions. Low effective stress leads to higher hydraulic conductivity. However, water overpressures up to 1.3 MPa did not cause hydrofracturing. Water injections performed in a filter previously used for gas injections, show that the occluded gas hinders the water flow and reduces the hydraulic conductivity by a factor two.

  13. Influence of vibrations of gas molecules on neutron reaction cross sections

    Science.gov (United States)

    Bowman, C. D.; Schrack, R. A.

    1980-01-01

    The change in molecular vibrational energy upon absorption of a neutron by a nucleus bound in a free molecule can influence resonance shape and other aspects of neutron reaction cross sections. A formalism is developed for centrosymmetric molecules such as UF6 and applied to the shape of the 6.67 eV resonance in 238U. The ratio of the resonance shape for 238UF6 gas and for solid 238U3O8 has been measured and compared with the calculation. Reasonable agreement is obtained indicating the validity of the calculation and the necessity to include vibration effects to avoid large errors in measurements and calculations on gascontaining systems. NUCLEAR REACTIONS 238U(n,γ) measured at 6.67 eV resonance; Effect of molecular vibrations studied experimentally and theoretically.

  14. Water Adsorption and Dissociation on Ceria-Supported Single-Atom Catalysts: A First-Principles DFT+U Investigation.

    Science.gov (United States)

    Han, Zhong-Kang; Gao, Yi

    2016-02-01

    Single-atom catalysts have attracted wide attention owing to their extremely high atom efficiency and activities. In this paper, we applied density functional theory with the inclusion of the on-site Coulomb interaction (DFT+U) to investigate water adsorption and dissociation on clean CeO 2 (111) surfaces and single transition metal atoms (STMAs) adsorbed on the CeO 2 (111) surface. It is found that the most stable water configuration is molecular adsorption on the clean CeO 2 (111) surface and dissociative adsorption on STMA/CeO 2 (111) surfaces, respectively. In addition, our results indicate that the more the electrons that transfer from STMA to the ceria substrate, the stronger the binding energies between the STMA and ceria surfaces. A linear relationship is identified between the water dissociation barriers and the d band centers of STMA, known as the generalized Brønsted-Evans-Polanyi principle. By combining the oxygen spillovers, single-atom dispersion stabilities, and water dissociation barriers, Zn, Cr, and V are identified as potential candidates for the future design of ceria-supported single-atom catalysts for reactions in which the dissociation of water plays an important role, such as the water-gas shift reaction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Demonstration of the Tilting of the Gas-Water Interface under Hydrodynamic Conditions.

    Science.gov (United States)

    Gretener, P. E.

    1979-01-01

    Describes the construction of an apparatus to demonstrate the tilting of an oil-water, gas-water, or gas-oil interface when the subsurface reservoir is under hydrodynamic conditions (i.e., when conditions of lateral flow exist). The model can be constructed of readily-available materials. (RE)

  16. Deep Conversion of Carbon Monoxide to Hydrogen and Formation of Acetate by the Anaerobic Thermophile Carboxydothermus hydrogenoformans

    OpenAIRE

    Henstra, Anne M.; Stams, Alfons J. M.

    2011-01-01

    Carboxydothermus hydrogenoformans is a thermophilic strictly anaerobic bacterium that catalyses the water gas shift reaction, the conversion of carbon monoxide with water to molecular hydrogen and carbon dioxide. The thermodynamically favorable growth temperature, compared to existing industrial catalytic processes, makes this organism an interesting alternative for production of cheap hydrogen gas suitable to fuel CO-sensitive fuel cells in a future hydrogen economy, provided sufficiently lo...

  17. Sodium-water reaction in double pool LMFBR, (5)

    International Nuclear Information System (INIS)

    Yoshida, Kazuo; Kumagai, Hiromichi; Nishi, Yoshihisa; Uotani, Masaki

    1990-01-01

    Experiments were conducted using a 1/5 scale model of the Double Pool in order to evaluate a pressure rise caused by a large scale sodium-water reaction. The experiments were focused on the pressure rise caused by the piston motion of liquid sodium. It appeared from the results that the magnitude of this pressure rise depends on the depth of reaction point, and that a pressure rise more than 1 MPa would arise in the real Double Pool plant. A new design of steam generator is proposed to mitigate the pressure rise. (author)

  18. Storm water permitting for oil and gas facilities

    International Nuclear Information System (INIS)

    de Blanc, P.C.

    1991-01-01

    After several false starts, the US Environmental Protection Agency (EPA) published new federal storm water regulations in the November 16, 1990 Federal Register. These regulations identify facilities which must apply for a storm water permit and detail permit application requirements. The regulations appear at 40 CFR 122 Subpart B and became effective December 17, 1990. An outline of these regulations and their applicability to oil and gas facilities is presented. They are: facilities which require a storm water permit; types of storm water permits; permit application deadlines; permit application forms; facilities with existing storm water permits; storm water permit application data requirements; storm water sampling and analysis requirements; and EPA contacts for additional information

  19. Isotope shifting capacity of rock

    International Nuclear Information System (INIS)

    Blattner, P.; Department of Scientific and Industrial Research, Lower Hutt

    1980-01-01

    Any oxygen isotope shifted rock volume exactly defines a past throughput of water. An expression is derived that relates the throughput of an open system to the isotope shift of reservoir rock and present-day output. The small isotope shift of Ngawha reservoir rock and the small, high delta oxygen-18 output are best accounted for by a magmatic water source

  20. Gas-phase reactions of glycine, alanine, valine and their N-methyl derivatives with the nitrosonium ion, NO+.

    Science.gov (United States)

    Freitas, M A; O'Hair, R A; Schmidt, J A; Tichy, S E; Plashko, B E; Williams, T D

    1996-10-01

    The gas-phase reactions of the nitrosonium ion, NO+ with the amino acids glycine, alanine and valine and their N-methyl derivatives were investigated under chemical ionization mass spectrometric (CIMS) conditions. Two products were observed in all cases: the formation of the iminium ion and the formation of an [M-H]+ ion. The latter product is consistent with a reaction channel involving hydride abstraction by NO+, and was confirmed by (i) examining the Ar+CI mass spectra of the same amino acids under similar source conditions and (ii) examining the unimolecular fragmentation reactions of the [M + H]+ ions of the N-nitroso-N-methyl derivatives of each of the amino acids in a tandem mass spectrometer. Further insights into the reaction of glycine with NO+ were obtained by performing ab initio calculations (at the MP2/6-31G* parallel HF/6-31G* level). These results indicate that four reactions are thermodynamically viable for glycine: (i) hydride abstraction; (ii) iminium ion formation (with concomitant loss of HONO and CO); (iii) diazonium ion formation; and (iv) diazonium ion formation followed by loss of N2. Possible reasons why reactions (iii) and (iv) are not observed are discussed, and comparisons with solution reactivity and the gas-phase reactivity of NO+ are also made.