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Sample records for supercritical water electronic

  1. Supercritical water

    CERN Document Server

    Marcus, Yizhak

    2012-01-01

    Discover the many new and emerging applications of supercritical water as a green solvent Drawing from thousands of original research articles, this book reviews and summarizes what is currently known about the properties and uses of supercritical water. In particular, it focuses on new and emerging applications of supercritical water as a green solvent, including the catalytic conversion of biomass into fuels and the oxidation of hazardous materials. Supercritical Water begins with an introduction that defines supercritical fluids in general. It then defines supercritical wa

  2. ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION

    Science.gov (United States)

    This engineering bulletin presents a description and status of supercritical water oxidation technology, a summary of recent performance tests, and the current applicability of this emerging technology. This information is provided to assist remedial project managers, contractors...

  3. Removing Solids From Supercritical Water

    Science.gov (United States)

    Hong, Glenn T.

    1992-01-01

    Apparatus removes precipitated inorganic salts and other solids in water-recycling process. Designed for use with oxidation in supercritical water which treats wastes and yields nearly pure water. Heating coils and insulation around vessel keep it hot. Locking bracket seals vessel but allows it to be easily opened for replacement of filled canisters.

  4. Supercritical Water Mixture (SCWM) Experiment

    Science.gov (United States)

    Hicks, Michael C.; Hegde, Uday G.

    2012-01-01

    The subject presentation, entitled, Supercritical Water Mixture (SCWM) Experiment, was presented at the International Space Station (ISS) Increment 33/34 Science Symposium. This presentation provides an overview of an international collaboration between NASA and CNES to study the behavior of a dilute aqueous solution of Na2SO4 (5% w) at near-critical conditions. The Supercritical Water Mixture (SCWM) investigation, serves as important precursor work for subsequent Supercritical Water Oxidation (SCWO) experiments. The SCWM investigation will be performed in DECLICs High Temperature Insert (HTI) for the purpose of studying critical fluid phenomena at high temperatures and pressures. The HTI includes a completely sealed and integrated test cell (i.e., Sample Cell Unit SCU) that will contain approximately 0.3 ml of the aqueous test solution. During the sequence of tests, scheduled to be performed in FY13, temperatures and pressures will be elevated to critical conditions (i.e., Tc = 374C and Pc = 22 MPa) in order to observe salt precipitation, precipitate agglomeration and precipitate transport in the presence of a temperature gradient without the influences of gravitational forces. This presentation provides an overview of the motivation for this work, a description of the DECLIC HTI hardware, the proposed test sequences, and a brief discussion of the scientific research objectives.

  5. Etching of glass microchips with supercritical water.

    Science.gov (United States)

    Karásek, Pavel; Grym, Jakub; Roth, Michal; Planeta, Josef; Foret, František

    2015-01-07

    A novel method of etching channels in glass microchips with the most tunable solvent, water, was tested as an alternative to common hydrogen fluoride-containing etchants. The etching properties of water strongly depend on temperature and pressure, especially in the vicinity of the water critical point. The chips were etched at the subcritical, supercritical and critical temperature of water, and the resulting channel shape, width, depth and surface morphology were studied by scanning electron microscopy and 3D laser profilometry. Channels etched with the hot water were compared with the chips etched with standard hydrogen fluoride-containing solution. Depending on the water pressure and temperature, the silicate dissolved from the glass could be re-deposited on the channel surface. This interesting phenomenon is described together with the conditions necessary for its utilization. The results illustrate the versatility of pure water as a glass etching and surface morphing agent.

  6. Supercritical water oxidation - Microgravity solids separation

    Science.gov (United States)

    Killilea, William R.; Hong, Glenn T.; Swallow, Kathleen C.; Thomason, Terry B.

    1988-01-01

    This paper discusses the application of supercritical water oxidation (SCWO) waste treatment and water recycling technology to the problem of waste disposal in-long term manned space missions. As inorganic constituents present in the waste are not soluble in supercritical water, they must be removed from the organic-free supercritical fluid reactor effluent. Supercritical water reactor/solids separator designs capable of removing precipitated solids from the process' supercritical fluid in zero- and low- gravity environments are developed and evaluated. Preliminary experiments are then conducted to test the concepts. Feed materials for the experiments are urine, feces, and wipes with the addition of reverse osmosis brine, the rejected portion of processed hygiene water. The solid properties and their influence on the design of several oxidation-reactor/solids-separator configurations under study are presented.

  7. Water in supercritical carbon dioxide dyeing

    Directory of Open Access Journals (Sweden)

    Zheng Lai-Jiu

    2015-01-01

    Full Text Available This paper investigates the effect of water serving as entrainer on the dyeing of wool fabrics in supercritical carbon dioxide. Compared with previous supercritical dyeing methods, addition of water makes the dyeing process more effective under low temperature and low pressure. During dyeing process, dyestuff can be uniformly distributed on fabrics’s surface due to water interaction, as a result coloration is enhanced while color difference is decreased.

  8. Oxidation behavior of Incoloy 800 under simulated supercritical water conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fulger, M. [Institute for Nuclear Research Pitesti, POB 78, Campului Street, No. 1, 115400 Mioveni (Romania)], E-mail: manuela.fulger@nuclear.ro; Ohai, D.; Mihalache, M.; Pantiru, M. [Institute for Nuclear Research Pitesti, POB 78, Campului Street, No. 1, 115400 Mioveni (Romania); Malinovschi, V. [University of Pitesti, Research Center for Advanced Materials, Targul din Vale Street, No. 1, 110040 Pitesti (Romania)

    2009-03-31

    For a correct design of supercritical water-cooled reactor (SCWR) components, data regarding the behavior of candidate materials in supercritical water are necessary. Corrosion has been identified as a critical problem because the high temperature and the oxidative nature of supercritical water may accelerate the corrosion kinetics. The goal of this paper is to investigate the oxidation behavior of Incoloy 800 exposed in autoclaves under supercritical water conditions for up to 1440 h. The exposure conditions (thermal deaerated water, temperatures of 723, 773, 823 and 873 K and a pressure of 25 MPa) have been selected as relevant for a supercritical power plant concept. To investigate the structural changes of the oxide films, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and electrochemical impedance spectroscopy (EIS) analyses were used. Results show changes in the oxides chemical composition, microstructure and thickness versus testing conditions (pressure, temperature and time). The oxide films are composed of two layers: an outer layer enriched in Fe oxide and an inner layer enriched in Cr and Ni oxides corresponding to small cavities supposedly due to internal oxidation.

  9. Destruction of Energetic Materials in Supercritical Water

    Science.gov (United States)

    2002-06-25

    THERMOCHEMISTRY OF ENERGETIC MATERIALS IN SUPERCRITICAL WATER...fringe spacing is 13.5 µm and the acoustic signal period is 28.3 ns. 138 SECTION VI THERMOCHEMISTRY OF ENERGETIC MATERIALS IN...validation calculation studied the solvation free energies of alkali–chloride ion pairs in liquid water. Such information can teach us about the

  10. Density dependence of the yield of hydrated electrons in the low-LET radiolysis of supercritical water at 400 °C: influence of the geminate recombination of subexcitation-energy electrons prior to thermalization.

    Science.gov (United States)

    Meesungnoen, Jintana; Sanguanmith, Sunuchakan; Jay-Gerin, Jean-Paul

    2013-10-21

    Monte Carlo simulations were used to calculate the yield of hydrated electrons (eaq(-)) in the low-linear energy transfer radiolysis of supercritical water at 400 °C as a function of water density over the range of ~0.15 to 0.6 g cm(-3). Very good agreement was found between our calculations and picosecond pulse radiolysis experimental data at ~60 ps and 1 ns at high density (>0.35 g cm(-3)). At densities lower than ~0.35 g cm(-3), our eaq(-) yields were lower than the experimental data, especially at ~60 ps. However, if we incorporated into the simulations a prompt geminate electron-cation (H2O˙(+)) recombination (prior thermalization of the electron) that decreased as the density decreased, our computed eaq(-) yields at ~60 ps and 1 ns compared fairly well with the experimental data for the entire density range studied.

  11. Supercritical-pressure light water cooled reactors

    CERN Document Server

    Oka, Yoshiaki

    2014-01-01

    This book focuses on the latest reactor concepts, single pass core and experimental findings in thermal hydraulics, materials, corrosion, and water chemistry. It highlights research on supercritical-pressure light water cooled reactors (SCWRs), one of the Generation IV reactors that are studied around the world. This book includes cladding material development and experimental findings on heat transfer, corrosion and water chemistry. The work presented here will help readers to understand the fundamental elements of reactor design and analysis methods, thermal hydraulics, materials and water

  12. The pseudocritical regions for supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Imre, A.R., E-mail: imre.attila@energia.mta.hu [HAS Centre for Energy Research, Thermohydraulics Department, P.O. Box 49, H-1525 Budapest (Hungary); University Cologne, Institute for Physical Chemistry, Luxemburger Str. 116, D-50939 Koeln (Germany); Deiters, U.K.; Kraska, T. [University Cologne, Institute for Physical Chemistry, Luxemburger Str. 116, D-50939 Koeln (Germany); Tiselj, I. [Jozef Stefan Institute, Reactor Engineering Division, Jamova 39, 1000 Ljubljana (Slovenia)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Supercritical water behaves anomalously around the Widom lines. Black-Right-Pointing-Pointer We calculated the location of the Widom lines for several thermodynamic functions. Black-Right-Pointing-Pointer Simple quadratic fitting equations are given to describe these lines. - Abstract: Vapour pressure curves and stability lines can be extended beyond the critical points into the supercritical domain by so-called Widom lines, along which some thermodynamic property undergoes a rapid change and liquid-like behaviour turns to vapour-like one. Knowledge about such lines is therefore important for thermohydraulic calculations and design. There are several properties that can be chosen as defining property of a Widom line. In this short note we calculate and compare several kinds of Widom lines for water.

  13. Reaction Behavior of Unsaturated Compounds in Sub- and Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    K. Kobiro

    2005-01-01

    @@ 1Introduction Much attention has been paid on the chemistry of sub- and supercritical water, because of their unique prosperities such as low viscosity, low polarity, and high solubility to organic compounds[1]. Recently, the unique sub- and supercritical water is applied as reaction media and reaction catalysts for organic reactions[2,3].We herein disclose the unique reaction of unsaturated compounds in sub- and supercritical water with specific interaction between unsaturated bond(s) and high-density and high-energy water molecule(s) in sub- and supercritical water.

  14. Supercritical water oxidation of products of human metabolism

    Science.gov (United States)

    Tester, Jefferson W.; Orge A. achelling, Richard K. ADTHOMASSON; Orge A. achelling, Richard K. ADTHOMASSON

    1986-01-01

    Although the efficient destruction of organic material was demonstrated in the supercritical water oxidation process, the reaction kinetics and mechanisms are unknown. The kinetics and mechanisms of carbon monoxide and ammonia oxidation in and reaction with supercritical water were studied experimentally. Experimental oxidation of urine and feces in a microprocessor controlled system was performed. A minaturized supercritical water oxidation process for space applications was design, including preliminary mass and energy balances, power, space and weight requirements.

  15. Water extractable arabinoxylan aerogels prepared by supercritical CO2 drying.

    Science.gov (United States)

    Marquez-Escalante, Jorge; Carvajal-Millan, Elizabeth; Miki-Yoshida, Mario; Alvarez-Contreras, Lorena; Toledo-Guillén, Alma Rosa; Lizardi-Mendoza, Jaime; Rascón-Chu, Agustín

    2013-05-14

    Water extractable arabinoxylan (WEAX) aerogels were prepared by extracting the solvent from the alcogels (WEAX hydrogels with an alcohol as the solvent) with carbon dioxide under supercritical conditions. WEAX aerogels were characterized using scanning electron microscopy and adsorption and desorption nitrogen isotherms. The micrographs indicate a heterogeneous porous network structure in WEAX aerogel. Adsorption/desorption nitrogen isotherms of this material were type IV, which confirm that this material possess a mesoporous structure. WEAX aerogels rehydration capability was evaluated and the water absorption mechanism was determined. The WEAX aerogels water absorption mechanism was non-Fickian (n = 0.54).

  16. Water Extractable Arabinoxylan Aerogels Prepared by Supercritical CO2 Drying

    Directory of Open Access Journals (Sweden)

    Agustín Rascón-Chu

    2013-05-01

    Full Text Available Water extractable arabinoxylan (WEAX aerogels were prepared by extracting the solvent from the alcogels (WEAX hydrogels with an alcohol as the solvent with carbon dioxide under supercritical conditions. WEAX aerogels were characterized using scanning electron microscopy and adsorption and desorption nitrogen isotherms. The micrographs indicate a heterogeneous porous network structure in WEAX aerogel. Adsorption/desorption nitrogen isotherms of this material were type IV, which confirm that this material possess a mesoporous structure. WEAX aerogels rehydration capability was evaluated and the water absorption mechanism was determined. The WEAX aerogels water absorption mechanism was non-Fickian (n = 0.54.

  17. Valorization of horse manure through catalytic supercritical water gasification.

    Science.gov (United States)

    Nanda, Sonil; Dalai, Ajay K; Gökalp, Iskender; Kozinski, Janusz A

    2016-06-01

    The organic wastes such as lignocellulosic biomass, municipal solid waste, sewage sludge and livestock manure have attracted attention as alternative sources of energy. Cattle manure, a waste generated in surplus amounts from the feedlot, has always been a chief environmental concern. This study is focused on identifying the candidacy of horse manure as a next generation feedstock for biofuel production through supercritical water gasification. The horse manure was gasified in supercritical water to examine the effects of temperature (400-600°C), biomass-to-water ratio (1:5 and 1:10) and reaction time (15-45min) at a pressure range of 23-25MPa. The horse manure and resulting biochar were characterized through carbon-hydrogen-nitrogen-sulfur (CHNS), inductively coupled plasma-mass spectrometry (ICP-MS), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscopy (SEM). The effects of alkali catalysts such as NaOH, Na2CO3 and K2CO3 at variable concentrations (1-2wt%) were investigated to maximize the hydrogen yields. Supercritical water gasification of horse manure with 2wt% Na2CO3 at 600°C and 1:10 biomass-to-water ratio for 45min revealed maximum hydrogen yields (5.31mmol/g), total gas yields (20.8mmol/g) with greater carbon conversion efficiency (43.1%) and enhanced lower heating value of gas products (2920kJ/Nm(3)). The manure-derived biochars generated at temperatures higher than 500°C also demonstrated higher thermal stability (weight loss 70wt%) suggesting their application in enhancing soil fertility and carbon sequestration. The results propose that supercritical water gasification could be a proficient remediation technology for horse manure to generate hydrogen-rich gas products.

  18. Supercritical Water Liquefaction of Coal and Waste Tires

    National Research Council Canada - National Science Library

    Prapan KUCHONTHARA; Yukihiko MATSUMURA

    2001-01-01

      Supercritical water liquefaction of scrap tire rubber and Ishikari coal, separately and in mixtures was investigated to study the possible synergetic effects of coliquefaction between the feedstocks...

  19. Supercritical Water Oxidation Data Acquisition Testing

    Energy Technology Data Exchange (ETDEWEB)

    K. M. Garcia

    1996-08-01

    Supercritical Water Oxidation (SCWO) is a high pressure oxidation process that blends air, water, and organic waste material in an oxidizer in which where the temperature and pressure in the oxidizer are maintained above the critical point of water. Supercritical water mixed with hydrocarbons, which would be insoluble at subcritical conditions, forms a homogeneous phase which possesses properties associated with both a gas and a liquid. Hydrocarbons in contact with oxygen and SCW are readily oxidized. These properties of SCW make it an attractive means for the destruction of waste streams containing organic materials. SCWO technology holds great promise for treating mixed wastes in an environmentally safe and efficient manner. In the spring of 1994 the U.S. Department of Energy (DOE) initiated a Supercritical Water Oxidation Data Acquisition Testing (SCWODAT) program. The SCWODAT program provided further information and operational data on the effectiveness of treating both simulated mixed waste and typical Navy hazardous waste using the SCWO technology. The program concentrated on the acquisition of data through pilot plant testing. The Phase I DOE testing used a simulated waste stream that contained a complex machine cutting oil and metals, that acted as surrogates for radionuclides. The Phase II Navy testing included pilot testing using hazardous waste materials to demonstrate the effectiveness of the SCWO technology. The SCWODAT program demonstrated that the SCWO process oxidized the simulated waste stream containing complex machine cutting oil, selected by DOE as representative of one of the most difficult of the organic waste streams for which SCWO had been applied. The simulated waste stream with surrogate metals in solution was oxidized, with a high destruction efficiency, on the order of 99.97%, in both the neutralized and unneutralized modes of operation.

  20. Supercritical Water Process for the Chemical Recycling of Waste Plastics

    Science.gov (United States)

    Goto, Motonobu

    2010-11-01

    The development of chemical recycling of waste plastics by decomposition reactions in sub- and supercritical water is reviewed. Decomposition reactions proceed rapidly and selectively using supercritical fluids compared to conventional processes. Condensation polymerization plastics such as PET, nylon, and polyurethane, are relatively easily depolymerized to their monomers in supercritical water. The monomer components are recovered in high yield. Addition polymerization plastics such as phenol resin, epoxy resin, and polyethylene, are also decomposed to monomer components with or without catalysts. Recycling process of fiber reinforced plastics has been studied. Pilot scale or commercial scale plants have been developed and are operating with sub- and supercritical fluids.

  1. Supercritical water oxidation treatment of textile sludge.

    Science.gov (United States)

    Zhang, Jie; Wang, Shuzhong; Li, Yanhui; Lu, Jinling; Chen, Senlin; Luo, XingQi

    2016-10-17

    In this work, we studied the supercritical water oxidation (SCWO) of the textile sludge, the hydrothermal conversion of typical textile compounds and the corrosion properties of stainless steel 316. Moreover, the influence mechanisms of NaOH during these related processes were explored. The results show that decomposition efficiency for organic matter in liquid phase of the textile sludge was improved with the increment of reaction temperature or oxidation coefficient. However, the organic substance in solid phase can be oxidized completely in supercritical water. Serious coking occurred during the high pressure water at 250-450°C for the Reactive Orange 7, while at 300 and 350°C for the polyvinyl alcohol. The addition of NaOH not only accelerated the destruction of organic contaminants in the SCWO reactor, but effectively inhibited the dehydration conversion of textile compounds during the preheating process, which was favorable for the treatment system of textile sludge. The corrosion experiment results indicate that the stainless steel 316 could be competent for the body materials of the reactor and the heat exchangers. Furthermore, there was prominent enhancement of sodium hydroxide for the corrosion resistance of 316 in subcritical water. On the contrary the effect was almost none during SCWO.

  2. Polarization and spectral shift of benzophenone in supercritical water.

    Science.gov (United States)

    Fonseca, T L; Georg, H C; Coutinho, K; Canuto, S

    2009-04-30

    Monte Carlo simulation and quantum mechanics calculations based on the INDO/CIS and TD-DFT methods were utilized to study the solvatochromic shift of benzophenone when changing the environment from normal water to supercritical (P = 340.2 atm and T = 673 K) condition. Solute polarization increases the dipole moment of benzophenone, compared to gas phase, by 88 and 35% in normal and supercritical conditions, giving the in-solvent dipole value of 5.8 and 4.2 D, respectively. The average number of solute-solvent hydrogen bonds was analyzed, and a large decrease of 2.3 in normal water to only 0.8 in the supercritical environment was found. By using these polarized models of benzophenone in the two different conditions of water, we performed MC simulations to generate statistically uncorrelated configurations of the solute surrounded by the solvent molecules and subsequent quantum mechanics calculations on these configurations. When changing from normal to supercritical water environment, INDO/CIS calculations explicitly considering all valence electrons of the 235 solvent water molecules resulted in a solvatochromic shift of 1425 cm(-1) for the most intense pi-pi* transition of benzophenone, that is, slightly underestimated in comparison with the experimentally inferred result of 1700 cm(-1). TD-B3LYP/6-311+G(2d,p) calculations on the same configurations but with benzophenone electrostatically embedded in the 320 water molecules resulted in a solvatochromic shift of 1715 cm(-1) for this transition, in very good agreement with the experimental result. When using the unpolarized model of the benzophenone, this calculated solvatochromic shift was only 640 cm(-1). Additional calculations were also made by using BHandHLYP/6-311+G(2d,p) to analyze the effect of the asymptotic decay of the exchange functional. This study indicates that, contrary to the general expectation, there is a sizable solute polarization even in the low-density regime of supercritical condition and

  3. Selective Synthesis of Manganese/Silicon Complexes in Supercritical Water

    Directory of Open Access Journals (Sweden)

    Jiancheng Wang

    2014-01-01

    Full Text Available A series of manganese salts (Mn(NO32, MnCl2, MnSO4, and Mn(Ac2 and silicon materials (silica sand, silica sol, and tetraethyl orthosilicate were used to synthesize Mn/Si complexes in supercritical water using a tube reactor. X-ray diffraction (XRD, X-ray photoelectron spectrometer (XPS, transmission electron microscopy (TEM, and scanning electron microscopy (SEM were employed to characterize the structure and morphology of the solid products. It was found that MnO2, Mn2O3, and Mn2SiO4 could be obtained in supercritical water at 673 K in 5 minutes. The roles of both anions of manganese salts and silicon species in the formation of manganese silicon complexes were discussed. The inorganic manganese salt with the oxyacid radical could be easily decomposed to produce MnO2/SiO2 and Mn2O3/SiO2. It is interesting to found that Mn(Ac2 can react with various types of silicon to produce Mn2SiO4. The hydroxyl groups of the SiO2 surface from different silicon sources enhance the reactivity of SiO2.

  4. Gasification of cyanobacterial in supercritical water.

    Science.gov (United States)

    Zhang, Huiwen; Zhu, Wei; Xu, Zhirong; Gong, Miao

    2014-01-01

    Cyanobacterial collected from eutrophic freshwater lakes constituted intractable waste with a rich algae biomass content. Supercritical water gasification (SCWG) was proposed to treat the cyanobacterial and to produce hydrogen for energy. The H 2 yield reached 2.92 mol/kg at reaction conditions of 500 °C, 30 min and 22 MPa; this yield accounted for 26% of the total gaseous products. Abundant ammonia and dissolved reactive phosphorous were concentrated in the liquid product, which could be recovered and used as a liquid fertilizer. Solid residue, which accounted only for about 1% of the wet weight, was mainly composed of coke and ash. The efficiency of H 2 production was better than that from other biomass, because of the abundant organic matter in cyanobacterial. Thus, cyanobacterial are an ideal biomass feedstock for H 2 production from SCWG.

  5. Supercritical water oxidation of landfill leachate.

    Science.gov (United States)

    Wang, Shuzhong; Guo, Yang; Chen, Chongming; Zhang, Jie; Gong, Yanmeng; Wang, Yuzhen

    2011-01-01

    In this paper, ammonia as an important ingredient in landfill leachate was mainly studied. Based on Peng-Robinson formulations and Gibbs free energy minimization method, the estimation of equilibrium composition and thermodynamic analysis for supercritical water oxidation of ammonia (SCWO) was made. As equilibrium is reached, ammonia could be totally oxidized in SCW. N(2) is the main product, and the formation of NO(2) and NO could be neglected. The investigation on SCWO of landfill leachate was conducted in a batch reactor at temperature of 380-500 °C, reaction time of 50-300s and pressure of 25 MPa. The effect of reaction parameters such as oxidant equivalent ratio, reaction time and temperature were investigated. The results showed that COD and NH(3) conversion improved as temperature, reaction time and oxygen excess increased. Compared to organics, NH(3) is a refractory compound in supercritical water. The conversion of COD and NH(3) were higher in the presence of MnO(2) than that without catalyst. The interaction between reaction temperature and time was analyzed by using response surface method (RSM) and the results showed that its influence on the NH(3) conversion was relatively insignificant in the case without catalyst. A global power-law rate expression was regressed from experimental data to estimate the reaction rate of NH(3). The activation energy with and without catalyst for NH(3) oxidation were 107.07 ± 8.57 kJ/mol and 83.22 ± 15.62 kJ/mol, respectively.

  6. Corrosion behavior of Hastelloy C-276 in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Qiang [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China); Tang Rui [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China)], E-mail: xajttr@163.com; Yin Kaiju; Luo Xin [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, P.O. Box 436, Chendu 610041 (China); Zhang Lefu [College of Nuclear Science and Technology, Shanghai Jiaotong University, Shanghai 200240 (China)

    2009-09-15

    The corrosion behavior of a nickel-based alloy Hastelloy C-276 exposed in supercritical water at 500-600 deg. C/25 MPa was investigated by means of gravimetry, scanning electron microscopy/energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. An oxide scale with dual-layer structure, mainly consisting of an outer NiO layer and an inner Cr{sub 2}O{sub 3}/NiCr{sub 2}O{sub 4}-mixed layer, developed on C-276 after 1000 h exposure. Higher temperature promoted oxidation, resulting in thicker oxide scale, larger weight gain and stronger tendency of oxide spallation. The oxide growth mechanism in SCW seems to be similar to that in high temperature water vapor, namely solid-state growth mechanism.

  7. Application of Neutron Radiography to Flow Visualization in Supercritical Water

    Science.gov (United States)

    Takenaka, N.; Sugimoto, K.; Takami, S.; Sugioka, K.; Tsukada, T.; Adschiri, T.; Saito, Y.

    Supercritical water is used in various chemical reaction processes including hydrothermal synthesis of metal oxide nano-particles, oxidation, chemical conversion of biomass and plastics. Density of the super critical water is much less than that of the sub-critical water. By using neutron radiography, Peterson et al. have studied salt precipitation processes in supercritical water and the flow pattern in a reverse-flow vessel for salt precipitation, and Balasko et al. have revealed the behaviour of supercritical water in a container. The nano-particles were made by mixing the super critical flow and the sub critical water solution. In the present study, neutron radiography was applied to the flow visualization of the super and sub critical water mixture in a T-junction made of stainless steel pipes for high pressure and temperature conditions to investigate their mixing process. Still images by a CCD camera were obtained by using the neutron radiography system at B4 port in KUR.

  8. Effects of Gravity on Supercritical Water Oxidation (SCWO) Processes

    Science.gov (United States)

    Hegde, Uday; Hicks, Michael

    2013-01-01

    The effects of gravity on the fluid mechanics of supercritical water jets are being studied at NASA to develop a better understanding of flow behaviors for purposes of advancing supercritical water oxidation (SCWO) technologies for applications in reduced gravity environments. These studies provide guidance for the development of future SCWO experiments in new experimental platforms that will extend the current operational range of the DECLIC (Device for the Study of Critical Liquids and Crystallization) Facility on board the International Space Station (ISS). The hydrodynamics of supercritical fluid jets is one of the basic unit processes of a SCWO reactor. These hydrodynamics are often complicated by significant changes in the thermo-physical properties that govern flow behavior (e.g., viscosity, thermal conductivity, specific heat, compressibility, etc), particularly when fluids transition from sub-critical to supercritical conditions. Experiments were conducted in a 150 ml reactor cell under constant pressure with water injections at various flow rates. Flow configurations included supercritical jets injected into either sub-critical or supercritical water. Profound gravitational influences were observed, particularly in the transition to turbulence, for the flow conditions under study. These results will be presented and the parameters of the flow that control jet behavior will be examined and discussed.

  9. Coal gasification with water under supercritical conditions

    Energy Technology Data Exchange (ETDEWEB)

    A.A. Vostrikov; S.A. Psarov; D.Yu. Dubov; O.N. Fedyaeva; M.Ya. Sokol [Russian Academy of Sciences, Novosibirsk (Russian Federastion). Kutateladze Institute of Thermophysics, Siberian Division

    2007-08-15

    The conversion of an array of coal particles in supercritical water (SCW) was studied in a semibatch reactor at a pressure of 30 MPa, 500-750{sup o}C, and a reaction time of 1-12 min. The bulk conversion, surface conversion, and random pore models were used to describe the conversion. The quantitative composition of reaction products was determined, and the dependence of the rate of reaction on the degree of coal conversion, reaction time, and reaction temperature was obtained on the assumption of a first-order reaction and the Arrhenius function. It was found that the gasification of coal under SCW conditions without the addition of oxidizing agents is a weakly endothermic process. The addition of CO{sub 2} to SCW decreased the rate of conversion and increased the yield of CO. It was found that, at a 90% conversion of the organic matter of coal (OMC) in a flow of SCW in a time of 2 min, the process power was 26 W/g per gram of OMC.

  10. Kinetics of coal conversion in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Anatoli A. Vostrikov; Sergey A. Psarov; Dmitri Yu. Dubov; Oxana N. Fedyaeva; Mikhail Ya. Sokol [Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation). Institute of Thermophysics

    2007-09-15

    Conversion of the coal particle pack in supercritical water (SCW) was studied in the semibatch reactor under the pressure of P = 30 MPa, in the temperature range of T = 500-750{sup o}C, and in the reaction time of t = 60-720 s. The experimental results were analyzed within the framework of homogeneous, nonreacted core, and random pore models. The quantitative composition of conversion products was determined. Dependences of the conversion rate on the degree of coal conversion, reaction time, and temperature were described in an assumption of the first-order reaction and Arrhenius dependence. It was found that activation energy of conversion is E = 103 kJ/mol and the pre-exponential factor is A{sub 0} = 1.3 x 10{sup 3.1} s{sup -1}. It was revealed that coal gasification in SCW without oxidants is the weakly endothermic process. The addition of CO{sub 2} into SCW decreases the conversion rate and increases the CO yield. 20 refs., 8 figs.

  11. Digested sewage sludge gasification in supercritical water.

    Science.gov (United States)

    Zhai, Yunbo; Wang, Chang; Chen, Hongmei; Li, Caiting; Zeng, Guangming; Pang, Daoxiong; Lu, Pei

    2013-04-01

    Digested sewage sludge gasification in supercritical water was studied. Influences of main reaction parameters, including temperature (623-698 K), pressure (25-35 Mpa), residence time (10-15 min) and dry matter content (5-25 wt%), were investigated to optimize the gasification process. The main gas products were methane, carbon monoxide, carbon dioxide and traces of ethene, etc. Results showed that 10 wt% dry matter content digested sewage sludge at a temperature of 698 K and residence time of 50 min, with a pressure of 25 MPa, were the most favorable conditions for the sewage sludge gasification and carbon gasification efficiencies. In addition, potassium carbonate (K2CO3) was also employed as the catalyst to make a comparison between gasification with and without catalyst. When 2.6 g K2CO3 was added, a gasification efficiency of 25.26% and a carbon gasification efficiency of 20.02% were achieved, which were almost four times as much as the efficiencies without catalyst. K2CO3 has been proved to be effective in sewage sludge gasification.

  12. Supercritical water pyrolysis of sewage sludge.

    Science.gov (United States)

    Ma, Wenchao; Du, Guiyue; Li, Jian; Fang, Yuanhao; Hou, Li'an; Chen, Guanyi; Ma, Degang

    2017-01-01

    Municipal sewage sludge (SS) from wastewater treatment plant containing high water content (>85wt.%), lead to the difficulty of co-combustion with MSW or coal due to the high cost of drying. This study explores an alternative method by supercritical water (SCW) pyrolysis of sewage sludge (SS) in a high pressure reaction vessel. The effects of temperature and moisture content of SS on yield and composition of the products (bio-oil, bio char and non-condensable gas) were studied. A temperature of 385°C and moisture content of 85wt.% were found to be the optimum conditions for the maximum bio-oil production of 37.23wt.%, with a higher heating value of 31.08MJ/kg. In the optimum condition, the yields of aliphatic hydrocarbon and phenols were about 29.23wt.% and 12.51wt.%, respectively. The physical and chemical properties of bio-char were analyzed by using XRF and BET. Results of GC analyses of NCG showed that it has the maximum HHV of 13.39MJ/m(3) at 445°C and moisture content of 85wt.%. The reaction path from SS to bio-oil through SCW pyrolysis was given. Moreover, carbon balance was calculated for the optimal condition, and finding out that 64.27wt.% of the carbon content was transferred from SS to bio-oil. Finally, this work demonstrates that the SCW pyrolysis is a promising disposal method for SS. Copyright © 2016. Published by Elsevier Ltd.

  13. 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

  14. Molecular Dynamics Investigation of Benzene in Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Microscopic structure and diffusion properties of benzene in ambient water (298 K, 0.1 MPa) and super critical water (673-773 K, 25-35 MPa) are investigated by molecular dynamics simulation with site-site models. It is found that at the ambient condition, the water molecules surrounding a benzene molecule form a hydrogen bond network. The hydrogen bond interaction between supercritical water molecules decreases dramatically under supercritical conditions. The diffusion coefficients of both the solute molecule and solvent molecule at supercritical conditions increase by 30-180 times than those at the ambient condition. With the temperature approaching the critical temperature, the change of diffusion coefficient with pressure becomes pronounced.

  15. Preliminary Design of In-Pile Supercritical Pressurized Water Test Loop

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Based on two proven technologies, current light water reactors (LWRs) and the supercritical coal-fired power plants, the supercritical water-cooled reactor (SCWR) is one of the six Generation-Ⅳ

  16. Exp6-polar thermodynamics of dense supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Bastea, S; Fried, L E

    2007-12-13

    We introduce a simple polar fluid model for the thermodynamics of dense supercritical water based on a Buckingham (exp-6) core and point dipole representation of the water molecule. The proposed exp6-polar thermodynamics, based on ideas originally applied to dipolar hard spheres, performs very well when tested against molecular dynamics simulations. Comparisons of the model predictions with experimental data available for supercritical water yield excellent agreement for the shock Hugoniot, isotherms and sound speeds, and are also quite good for the self-diffusion constant and relative dielectric constant. We expect the present approach to be also useful for other small polar molecules and their mixtures.

  17. Destruction of energetic materials by supercritical water oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Beulow, S.J.; Dyer, R.B.; Harradine, D.M.; Robinson, J.M.; Oldenborg, R.C.; Funk, K.A.; McInroy, R.E.; Sanchez, J.A.; Spontarelli, T.

    1993-10-01

    Supercritical water oxidation is a relatively low-temperature process that can give high destruction efficiencies for a variety of hazardous chemical wastes. Results are presented examining the destruction of high explosives and propellants in supercritical water and the use of low temperature, low pressure hydrolysis as a pretreatment process. Reactions of cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine (HMX), nitroguanidine (NQ), pentaerythritol tetranitrate (PETN), and 2,4,6-trinitrotoluene (TNT) are examined in a flow reactor operated at temperatures between 400{degrees}C and 650{degrees}C. Explosives are introduced into the reactor at concentrations below the solubility limits. For each of the compounds, over 99.9% is destroyed in less than 30 seconds at temperatures above 600{degrees}C. The reactions produce primarily N{sub 2}, N{sub 2}O,CO{sub 2}, and some nitrate and nitrite ions. The distribution of reaction products depends on reactor pressure, temperature, and oxidizer concentration. Kinetics studies of the reactions of nitrate and nitrite ions with various reducing reagents in supercritical water show that they can be rapidly and completely destroyed at temperatures above 525{degrees}C. The use of slurries and hydrolysis to introduce high concentrations of explosives into a supercritical water reactor is examined. For some compounds the rate of reaction depends on particle size. The hydrolysis of explosives at low temperatures (<100{degrees}C) and low pressures (<1 atm) under basic conditions produces water soluble, non-explosive products which are easily destroyed by supercritical water oxidation. Large pieces of explosives (13 cm diameter) have been successfully hydrolyzed. The rate, extent, and products of the hydrolysis depend on the type and concentration of base. Results from the base hydrolysis of triple base propellant M31A1E1 and the subsequent supercritical water oxidation of the hydrolysis products are presented.

  18. Supercritical water oxidation - Concept analysis for evolutionary Space Station application

    Science.gov (United States)

    Hall, John B., Jr.; Brewer, Dana A.

    1986-01-01

    The ability of a supercritical water oxidation (SCWO) concept to reduce the number of processes needed in an evolutionary Space Station design's Environmental Control and Life Support System (ECLSS), while reducing resupply requirements and enhancing the integration of separate ECLSS functions into a single Supercritical Water Oxidation process, is evaluated. While not feasible for an initial operational capability Space Station, the SCWO's application to the evolutionary Space Station configuration would aid the integration of eight ECLSS functions into a single one, thereby significantly reducing program costs.

  19. Treatment of sewage sludge in supercritical water and evaluation of the combined process of supercritical water gasification and oxidation.

    Science.gov (United States)

    Qian, Lili; Wang, Shuzhong; Xu, Donghai; Guo, Yang; Tang, Xingying; Wang, Longfei

    2015-01-01

    Influences of temperature and oxidation coefficient (n) on sewage sludge treatment in supercritical water and its corresponding reaction mechanism were studied. Moreover, the combined process of supercritical water gasification (SCWG) and supercritical water oxidation (SCWO) was also investigated. The results show that ammonia nitrogen, phenols and pyridines are main refractory intermediates. The weight of solid products at 873K and n=4 is only 3.5wt.% of the initial weight, which is lower than that after combustion. Volatile organics in solid phase have almost released at 723K and n=0. Highest yield of combustible gases was obtained at n=0, and H2 yield can reach 11.81mol/kg at 873K. Furthermore, the combination of SCWG at 723K and SCWO at 873K with a total n=1 is feasible for its good effluent quality and low operation costs.

  20. Accelerated Stress Corrosion Crack Initiation of Alloys 600 and 690 in Hydrogenated Supercritical Water

    Science.gov (United States)

    Moss, Tyler; Was, Gary S.

    2017-04-01

    The objective of this study is to determine whether stress corrosion crack initiation of Alloys 600 and 690 occurs by the same mechanism in subcritical and supercritical water. Tensile bars of Alloys 690 and 600 were strained in constant extension rate tensile experiments in hydrogenated subcritical and supercritical water from 593 K to 723 K (320 °C to 450 °C), and the crack initiation behavior was characterized by high-resolution electron microscopy. Intergranular cracking was observed across the entire temperature range, and the morphology, structure, composition, and temperature dependence of initiated cracks in Alloy 690 were consistent between hydrogenated subcritical and supercritical water. Crack initiation of Alloy 600 followed an Arrhenius relationship and did not exhibit a discontinuity or change in slope after crossing the critical temperature. The measured activation energy was 121 ± 13 kJ/mol. Stress corrosion crack initiation in Alloy 690 was fit with a single activation energy of 92 ± 12 kJ/mol across the entire temperature range. Cracks were observed to propagate along grain boundaries adjacent to chromium-depleted metal, with Cr2O3 observed ahead of crack tips. All measures of the SCC behavior indicate that the mechanism for stress corrosion crack initiation of Alloy 600 and Alloy 690 is consistent between hydrogenated subcritical and supercritical water.

  1. Accelerated Stress Corrosion Crack Initiation of Alloys 600 and 690 in Hydrogenated Supercritical Water

    Science.gov (United States)

    Moss, Tyler; Was, Gary S.

    2017-01-01

    The objective of this study is to determine whether stress corrosion crack initiation of Alloys 600 and 690 occurs by the same mechanism in subcritical and supercritical water. Tensile bars of Alloys 690 and 600 were strained in constant extension rate tensile experiments in hydrogenated subcritical and supercritical water from 593 K to 723 K (320 °C to 450 °C), and the crack initiation behavior was characterized by high-resolution electron microscopy. Intergranular cracking was observed across the entire temperature range, and the morphology, structure, composition, and temperature dependence of initiated cracks in Alloy 690 were consistent between hydrogenated subcritical and supercritical water. Crack initiation of Alloy 600 followed an Arrhenius relationship and did not exhibit a discontinuity or change in slope after crossing the critical temperature. The measured activation energy was 121 ± 13 kJ/mol. Stress corrosion crack initiation in Alloy 690 was fit with a single activation energy of 92 ± 12 kJ/mol across the entire temperature range. Cracks were observed to propagate along grain boundaries adjacent to chromium-depleted metal, with Cr2O3 observed ahead of crack tips. All measures of the SCC behavior indicate that the mechanism for stress corrosion crack initiation of Alloy 600 and Alloy 690 is consistent between hydrogenated subcritical and supercritical water.

  2. Reforming of methanol and glycerol in supercritical water

    NARCIS (Netherlands)

    van Bennekom, J. G.; Venderbosch, R. H.; Assink, D.; Heeres, H. J.

    2011-01-01

    Reforming of pure glycerol, crude glycerin, and methanol (pure and in the presence of Na(2)CO(3)) in supercritical water was investigated. Continuous experiments were carried out at temperatures between 450 and 650 degrees C, residence times between 6 and 173 s, and feed concentrations of 3-20 wt%.

  3. SUPERCRITICAL WATER OXIDATION MODEL DEVELOPMENT FOR SELECTED EPA PRIORITY POLLUTANTS

    Science.gov (United States)

    Supercritical Water Oxidation (SCWO) evaluated for five compounds: acetic acid, 2,4-dichlorophenol, pentachlorophenol, pyridine, 2,4-dichlorophenoxyacetic acid (methyl ester). inetic models were developed for acetic acid, 2,4-dichlorophenol, and pyridine. he test compounds were e...

  4. Treatment of municipal sewage sludge in supercritical water: A review.

    Science.gov (United States)

    Qian, Lili; Wang, Shuzhong; Xu, Donghai; Guo, Yang; Tang, Xingying; Wang, Laisheng

    2016-02-01

    With increasing construction of wastewater treatment plants and stricter policies, municipal sewage sludge (MSS) disposal has become a serious problem. Treatment of MSS in supercritical water (SCW) can avoid the pre-drying procedure and secondary pollution of conventional methods. SCW treatment methods can be divided into supercritical water gasification (SCWG), supercritical water partial oxidation (SCWPO) and supercritical water oxidation (SCWO) technologies with increasing amounts of oxidants. Hydrogen-rich gases can be generated from MSS by SCWG or SCWPO technology using oxidants less than stoichiometric ratio while organic compounds can be completely degraded by SCWO technology with using an oxidant excess. For SCWG and SCWPO technologies, this paper reviews the influences of different process variables (MSS properties, moisture content, temperature, oxidant amount and catalysts) on the production of gases. For SCWO technology, this paper reviews research regarding the removal of organics with or without hydrothermal flames and the changes in heavy metal speciation and risk. Finally, typical systems for handling MSS are summarized and research needs and challenges are proposed.

  5. Supercritical Water Gasification of Biomass: A Literature and Technology Overview

    NARCIS (Netherlands)

    Yakaboylu, O.; Harinck, J.; Smit, K.G.; De Jong, W.

    2014-01-01

    The supercritical water gasification process is an alternative to both conventional gasification as well as anaerobic digestion as it does not require drying and the process takes place at much shorter residence times; a few minutes at most. The drastic changes in the thermo-physical properties of w

  6. Supercritical water oxidation data acquisition testing. Final report, Volume I

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    This report discusses the phase one testing of a data acquisition system for a supercritical water waste oxidation system. The system is designed to destroy a wide range of organic materials in mixed wastes. The design and testing of the MODAR Oxidizer is discussed. An analysis of the optimized runs is included.

  7. Comparison of Nitronic 50 and Stainless Steel 316 for use in Supercritical Water Environments

    Science.gov (United States)

    Karmiol, Zachary

    Increased efficiency can greatly benefit any mode of power production. Many proposed coal, natural gas, and nuclear reactors attempt to realize this goal through the use of increased operating temperatures and pressures, and as such require materials capable of withstanding extreme conditions. One such design employs supercritical water, which in addition to high temperatures and pressures is also highly oxidizing. A critical understanding of both mechanical and oxidation characteristics of candidate materials are required to determine the viability of materials for these reactors. This work investigates two potential materials, austenitic stainless steels, namely, Nitronic-50 and stainless steel 316, for use in these conditions. The supercritical water loop at the University of Nevada, Reno allowed for the study of materials at both subcritical and supercritical conditions. The materials were investigated mechanically using slow strain rate tests under conditions ranging from an inert nitrogen atmosphere, to both subcritical and supercritical water, with the failed samples surface characterized by optical microscopy, scanning electron microscopy, and Raman spectroscopy. Electrochemical studies were performed via potentiodynamic polarization in subcritical water only, and characterized using Raman spectroscopy. The samples were also exposed to supercritical water, and characterized using Raman spectroscopy. Nitronic-50 was found to have superior mechanical characteristics to stainless steel 316. SS-316 was found to have a surface film consisting of iron oxides, while the surface film of N-50 consisted predominantly of nickel-iron spinel. The crack interior of the sample was different from the exterior, indicating that the time and temperature of the exposure might play a defining role in determining the chemistry of the film.

  8. Heat Transfer Phenomena in Supercritical Water Nuclear Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Mark H. Anderson; MichaelL. Corradini; Riccardo Bonazza; Jeremy R. Licht

    2007-10-03

    A supercritical water heat transfer facility has been built at the University of Wisconsin to study heat transfer in ancircular and square annular flow channel. A series of integral heat transfer measurements has been carried out over a wide range of heat flux, mas velocity and bulk water temperatures at a pressure of 25 MPa. The circular annular test section geometry is a 1.07 cm diameter heater rod within a 4.29 diameter flow channel.

  9. Reactions of supercritical water and supercritical methanol with benzaldehyde; Chorinkaisui oyobi chorinkai methanol to benzaldehyde tono hanno

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, C.; Yasuda, T.; Nishi, K.; Takahashi, S. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-11-01

    The reactions of supercritical water and supercritical methanol with benzaldehyde have been examined in the temperature range from 553 to 693 K, and the reaction pathways have been examined from the temporal variations of the reaction products. For the reaction of benzaldehyde with supercritical water, the major product was benzene, which was formed from the pyrolysis of benzaldehyde. The benzoic acid and benzyl alcohol were the by-products, produced from the Cannizzaro-type disproportionation reaction of benzaldehyde with the hydrate formed from the reaction with water and benzaldehyde. The major product for the reaction of benzaldehyde with supercritical methanol was benzyl alcohol, and the by-product were dimethylacetal, benzene, and methyl benzoic acid. Under the reaction conditions of this study, a significant amount of acetal was produced from benzaldehyde and methanol. The pyrolysis of acetal yielded benzyl alcohol. 29 refs., 6 figs., 4 tabs.

  10. Generic supercritical water technology; Generic technology to shite no chorinkaisui riyo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Arai, K.; Ajiri, M.; Inomata, H.; Smith, R.; Hakuta, Y. [Tohoku University, Sendai (Japan). Faculty of Engineering; Yokoyama, C. [Tohoku University, Sendai (Japan). The Institute forChemical Reaction Science; Chin, L. [New Energy and Industrial Technology Development Organization, Tokyo, (Japan)

    1997-02-01

    This paper describes the measurement and analysis for clarifying solution structure of supercritical water and exhibition mechanism of solvent functions. It also describes the development of new processes using supercritical water as reaction solvent. The PVT measurements were conducted in the supercritical region using pure water and NaCl aqueous solution, to confirm the reduction of molar volume of the electrolyte solution. The hydration structure was examined in the supercritical aqueous solution by the molecular dynamic simulation. As a result, presence of hydrogen bond structure, where the contribution of two branching hydrogen bond can not be ignored, was suggested under the supercritical condition. Characteristics of supercritical aqueous solutions are analyzed through in-situ Raman and scattered X-ray spectral measurements. Moreover, this paper introduces developments of some processes in the supercritical water, such as decomposition of wasted polymers, recovery of chemical materials, reforming of heavy hydrocarbons by contact hydrogenation, and synthesis of fine powders of metal oxide by reaction crystallization.

  11. Development of an Accelerated Methodology to Study Degradation of Materials in Supercritical Water for Application in High Temperature Power Plants

    Science.gov (United States)

    Rodriguez, David

    The decreasing supply of fossil fuel sources, coupled with the increasing concentration of green house gases has placed enormous pressure to maximize the efficiency of power generation. Increasing the outlet temperature of these power plants will result in an increase in operating efficiency. By employing supercritical water as the coolant in thermal power plants (nuclear reactors and coal power plants), the plant efficiency can be increased to 50%, compared to traditional reactors which currently operate at 33%. The goal of this dissertation is to establish techniques to characterize the mechanical properties and corrosion behavior of materials exposed to supercritical water. Traditionally, these tests have been long term exposure tests spanning months. The specific goal of this dissertation is to develop a methodology for accelerated estimation of corrosion rates in supercritical water that can be sued as a screening tool to select materials for long term testing. In this study, traditional methods were used to understand the degradation of materials in supercritical water and establish a point of comparison to the first electrochemical studies performed in supercritical water. Materials studied included austenitic steels (stainless steel 304, stainless steel 316 and Nitronic 50) and nickel based alloys (Inconel 625 and 718). Surface chemistry of the oxide layer was characterized using scanning electron microscopy, X-ray diffraction, FT-IR, Raman and X-ray photoelectron spectroscopies. Stainless steel 304 was subjected to constant tensile load creep tests in water at a pressure of 27 MPa and at temperatures of 200 °C, 315 °C and supercritical water at 450 °C for 24 hours. It was determined that the creep rate for stainless steel 304 exposed to supercritical water would be unacceptable for use in service. It was observed that the formation of hematite was favored in subcritical temperatures, while magnetite was formed in the supercritical region. Corrosion of

  12. Solubility of 1:1 Alkali Nitrates and Chlorides in Near-Critical and Supercritical Water : 1 Alkali Nitrates and Chlorides in Near-Critical and Supercritical Water

    NARCIS (Netherlands)

    Leusbrock, Ingo; Metz, Sybrand J.; Rexwinkel, Glenn; Versteeg, Geert F.

    2009-01-01

    To increase the available data oil systems containing supercritical water and inorganic compounds, all experimental setup was designed to investigate the solubilities of inorganic compounds Ill supercritical water, In this work, three alkali chloride salts (LiCl, NaCl, KCl) and three alkali nitrate

  13. Fundamental kinetics and mechanistic pathways for oxidation reactions in supercritical water

    Science.gov (United States)

    Webley, Paul A.; Tester, Jefferson W.

    1988-01-01

    Oxidation of the products of human metabolism in supercritical water has been shown to be an efficient way to accomplish the on-board water/waste recycling in future long-term space flights. Studies of the oxidation kinetics of methane to carbon dioxide in supercritical water are presented in this paper in order to enhance the fundamental understanding of the oxidation of human waste compounds in supercritical water. It is concluded that, although the elementary reaction models remain the best hope for simulating oxidation in supercritical water, several modifications to existing mechanisms need to be made to account for the role of water in the reaction mechanism.

  14. Molecular Dynamics Simulation of Diffusion Coefficients of Oxygen, Nitrogen and Sodium Chloride in Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    肖吉; 陆九芳; 陈健; 李以圭

    2001-01-01

    Molecular dynamics simulation has been performed to determine the infinite-dilution diffusion coefficients of oxygen and nitrogen, and the diffusion coefficients of NaCl in supercritical water from 703.2- 763.2 K and 30-45 MPa.The results obtained show that the diffusion coefficients in supercritical water increase with temperature, while decreasing with pressure. Nevertheless, the diffusion coefficients in supercritical water are much larger than those in normal water.

  15. Spontaneous Ignition of Hydrothermal Flames in Supercritical Ethanol Water Solutions

    Science.gov (United States)

    Hicks, Michael C.; Hegde, Uday G.; Kojima, Jun J.

    2017-01-01

    Results are reported from recent tests where hydrothermal flames spontaneously ignited in a Supercritical Water Oxidation (SCWO) Test Cell. Hydrothermal flames are generally categorized as flames that occur when appropriate concentrations of fuel and oxidizer are present in supercritical water (SCW); i.e., water at conditions above its critical point (218 atm and 374 C). A co-flow injector was used to inject fuel, comprising an aqueous solution of 30-vol to 50-vol ethanol, and air into a reactor held at constant pressure and filled with supercritical water at approximately 240 atm and 425 C. Hydrothermal flames auto-ignited and quickly stabilized as either laminar or turbulent diffusion flames, depending on the injection velocities and test cell conditions. Two orthogonal views, one of which provided a backlit shadowgraphic image, provided visual observations. Optical emission measurements of the steady state flame were made over a spectral range spanning the ultraviolet (UV) to the near infrared (NIR) using a high-resolution, high-dynamic-range spectrometer. Depending on the fuel air flow ratios varying degrees of sooting were observed and are qualitatively compared using light absorption comparisons from backlit images.

  16. Exploration of the gasification of Spirulina algae in supercritical water.

    Science.gov (United States)

    Miller, Andrew; Hendry, Doug; Wilkinson, Nikolas; Venkitasamy, Chandrasekar; Jacoby, William

    2012-09-01

    This study presents non-catalytic gasification of Spirulina algae in supercritical water using a plug flow reactor and a mechanism for feeding solid carbon streams into high pressure (>25 MPa) environments. A 2(III)(3-1) factorial experimental design explored the effect of concentration, temperature, and residence time on gasification reactions. A positive displacement pump fed algae slurries into the reactor at a temperature range of 550-600°C, and residence times between 4 and 9s. The results indicate that algae gasify efficiently in supercritical water, highlighting the potential for a high throughput process. Additional experiments determined Arrhenius parameters of Spirulina algae. This study also presents a model of the gasification reaction using the estimated activation energy (108 kJ/mol) and other Arrhenius parameters at plug flow conditions. The maximum rate of gasification under the conditions studied of 53 g/Ls is much higher than previously reported.

  17. ABRUPT DEFLECTED SUPERCRITICAL WATER FLOW IN SLOPED CHANNELS

    Institute of Scientific and Technical Information of China (English)

    LIU Ya-kun; NI Han-gen

    2008-01-01

    The effect of the bottom slope on abrupt deflected supercritical water flow was experimentally and theoretically studied. Model tests were conducted in a flume of 1.2 m wide and 2.6 m long with sloped bottom at an angle 35.54o, its length of deflector was 0.2 m and the deflection angles were 15o and 30o. An approximate method for calculatjng the shock wave angle and depth ratio of the abrupt deflected supercritical water flow was suggested, and a correction coefficient for the hydrodynamic pressure was introduced to generalize the momentum equation in the direction perpendicular to the shock front. It must be noticed that in the sloped channel the shock wave angle and the depth ratio are no longer constant as those in the horizontal channels, but slowly change along the shock front. The calculated results are in good agreement with measured data.

  18. Experimental study of choking flow of water at supercritical conditions

    Science.gov (United States)

    Muftuoglu, Altan

    Future nuclear reactors will operate at a coolant pressure close to 25 MPa and at outlet temperatures ranging from 500°C to 625°C. As a result, the outlet flow enthalpy in future Supercritical Water-Cooled Reactors (SCWR) will be much higher than those of actual ones which can increase overall nuclear plant efficiencies up to 48%. However, under such flow conditions, the thermal-hydraulic behavior of supercritical water is not fully known, e.g., pressure drop, forced convection and heat transfer deterioration, critical and blowdown flow rate, etc. Up to now, only a very limited number of studies have been performed under supercritical conditions. Moreover, these studies are conducted at conditions that are not representative of future SCWRs. In addition, existing choked flow data have been collected from experiments at atmospheric discharge pressure conditions and in most cases by using working fluids different than water which constrain researchers to analyze the data correctly. In particular, the knowledge of critical (choked) discharge of supercritical fluids is mandatory to perform nuclear reactor safety analyses and to design key mechanical components (e.g., control and safety relief valves, etc.). Hence, an experimental supercritical water facility has been built at Ecole Polytechnique de Montreal which allows researchers to perform choking flow experiments under supercritical conditions. The facility can also be used to carry out heat transfer and pressure drop experiments under supercritical conditions. In this thesis, we present the results obtained at this facility using a test section that contains a 1 mm inside diameter, 3.17 mm long orifice plate with sharp edges. Thus, 545 choking flow of water data points are obtained under supercritical conditions for flow pressures ranging from 22.1 MPa to 32.1 MPa, flow temperatures ranging from 50°C to 502°C and for discharge pressures from 0.1 MPa to 3.6 MPa. Obtained data are compared with the data given in

  19. Destruction of Navy Hazardous Wastes by Supercritical Water Oxidation

    Science.gov (United States)

    1994-08-01

    voltmeters and scanning thermocouple meters. The data are acquired, analyzed, filed, and displayed using software written for the LabWindows data...acquisition software from National Instruments Corporation. The code was written by NFESC in the C computer language and compiled to achieve rapid program...Hazards and operability ( HAZOP ) study of a supercritical water oxidation (SCWO) bench scale system. Cambridge, MA, Aug 1992. 8. Arthur D. Little, Inc

  20. Supercritical water oxidation of wastewater and sludges - design considerations

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, M.J.C.; Sanchez, E.A.; Fernandez-Polanco, F. [Dept. Ingenieria Quimica, Univ. de Valladolid, Valladolid (Spain)

    2002-07-01

    The supercritical water oxidation (SCWO) process is a promising technology for the treatment of industrial wastewaters and sludges. It has been shown to be effective in destroying recalcitrant, xenobiotic or nonbiodegradable compounds and is an interesting alternative to conventional chemical and biological oxidation processes. This paper describes the basic concepts and state of the art of the SCWO technology and presents the flow sheets and energy and mass balances for diluted wastewater and sludge treatment. (orig.)

  1. Supercritical Water Reactor Cycle for Medium Power Applications

    Energy Technology Data Exchange (ETDEWEB)

    BD Middleton; J Buongiorno

    2007-04-25

    Scoping studies for a power conversion system based on a direct-cycle supercritical water reactor have been conducted. The electric power range of interest is 5-30 MWe with a design point of 20 MWe. The overall design objective is to develop a system that has minimized physical size and performs satisfactorily over a broad range of operating conditions. The design constraints are as follows: Net cycle thermal efficiency {ge}20%; Steam turbine outlet quality {ge}90%; and Pumping power {le}2500 kW (at nominal conditions). Three basic cycle configurations were analyzed. Listed in order of increased plant complexity, they are: (1) Simple supercritical Rankine cycle; (2) All-supercritical Brayton cycle; and (3) Supercritical Rankine cycle with feedwater preheating. The sensitivity of these three configurations to various parameters, such as reactor exit temperature, reactor pressure, condenser pressure, etc., was assessed. The Thermoflex software package was used for this task. The results are as follows: (a) The simple supercritical Rankine cycle offers the greatest hardware simplification, but its high reactor temperature rise and reactor outlet temperature may pose serious problems from the viewpoint of thermal stresses, stability and materials in the core. (b) The all-supercritical Brayton cycle is not a contender, due to its poor thermal efficiency. (c) The supercritical Rankine cycle with feedwater preheating affords acceptable thermal efficiency with lower reactor temperature rise and outlet temperature. (d) The use of a moisture separator improves the performance of the supercritical Rankine cycle with feedwater preheating and allows for a further reduction of the reactor outlet temperature, thus it was selected for the next step. Preliminary engineering design of the supercritical Rankine cycle with feedwater preheating and moisture separation was performed. All major components including the turbine, feedwater heater, feedwater pump, condenser, condenser pump

  2. System model for gasification of biomass model compounds in supercritical water – a thermodynamic analysis

    NARCIS (Netherlands)

    Withag, Jan A.M.; Smeets, Jules R.; Bramer, Eddy A.; Brem, Gerrit

    2012-01-01

    This article presents a system model for the process of gasification of biomass model compounds in supercritical water. Supercritical water gasification of wet biomass (water content of 70 wt% or more) has as the main advantage that conversion may take place without the costly drying step. The therm

  3. System model for gasification of biomass model compounds in supercritical water - A thermodynamic analysis

    NARCIS (Netherlands)

    Withag, J.A.M.; Smeets, Jules R.; Bramer, E.A.; Brem, G.

    2012-01-01

    This article presents a system model for the process of gasification of biomass model compounds in supercritical water. Supercritical water gasification of wet biomass (water content of 70 wt% or more) has as the main advantage that conversion may take place without the costly drying step. The therm

  4. The separation of particulates from supercritical water oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Dell`Orco, P.C.; Li, L.; Gloyna, E.F. [Univ. of Texas, Austin (United States)

    1993-01-01

    Small hydrocyclones with batch underflow receivers were assessed for their ability to separate micron-sized particulates from near-critical water solutions. Such particulates are expected from the effluent of a supercritical water oxidation reactor. The separation of micron-sized quartz silica, zirconia, and titania particles was investigated. An empirical expression was developed for the prediction of gross removal efficiencies as a function of a Stokes` number. Particle size distributions provided grade efficiencies for all experiments, and from these data, cut sizes were determined. Gross efficiencies up to 99% were observed for zirconia; cut sizes (d{sub 90} and d{sub 95}) near one micron were measured.

  5. On the cluster composition of supercritical water combining molecular modeling and vibrational spectroscopic data.

    Science.gov (United States)

    Tassaing, T; Garrain, P A; Bégué, D; Baraille, I

    2010-07-21

    The present study is aimed at a detailed analysis of supercritical water structure based on the combination of experimental vibrational spectra as well as molecular modeling calculations of isolated water clusters. We propose an equilibrium cluster composition model where supercritical water is considered as an ideal mixture of small water clusters (n=1-3) at the chemical equilibrium and the vibrational spectra are expected to result from the superposition of the spectra of the individual clusters, Thus, it was possible to extract from the decomposition of the midinfrared spectra the evolution of the partition of clusters in supercritical water as a function of density. The cluster composition predicted by this model was found to be quantitatively consistent with the near infrared and Raman spectra of supercritical water analyzed using the same procedure. We emphasize that such methodology could be applied to determine the portion of cluster in water in a wider thermodynamic range as well as in more complex aqueous supercritical solutions.

  6. The separation of particles from supercritical water oxidation effluents

    Energy Technology Data Exchange (ETDEWEB)

    Dell' Orco, P.C.

    1991-08-01

    The development of a solids separation system is essential to the implementation of supercritical water oxidation as a commercial process. Like all waste disposal processes, supercritical water oxidation produces a residue. This final ash must eventually be removed from the effluent stream. Limited studies have investigated solids separations near supercritical water conditions (374.2 {degrees}C, 3205 psi). Therefore, a ten millimeter diameter hydrocyclone with an underflow receiver was evaluated for its ability to achieve the separation of fine particles from water. Temperature was varied from 20{degrees}C to 389{degrees}C while pressure was maintained at 3600 psi (24.8 MPa). Mass flow rates varied from 0.015 to 0.049 kg/s. Particle concentrations in feed streams ranged from 400 to 1200 mg/L. Three different particulates, Min-U-Sil 5 (quartz SiO{sub 2}), zirconium dioxide (ZrO{sub 2}), and titanium dioxide (TiO{sub 2}) were studied. These particles ranged in diameter from below one micron to ten microns. Low pressure (0-200 psi), room temperature (20{degrees}C) studies were also conducted where flow rate and feed concentration were variables. Solids removal efficiencies were determined for all experiments. Solid removals were as high as 99% at elevated temperatures. Particle size distributions provided information on particle sizes separated. Particles removed with efficiencies of 50, 90, and 95 per cent (cut sizes) were determined. Ninety per cent cut sizes below one micron were reported for several elevated temperature experiments. Empirical models for use in engineering design were developed for the prediction of solid removal efficiencies and pressure drops.

  7. Continuous supercritical water gasification of isooctane: A promising reactor design

    Energy Technology Data Exchange (ETDEWEB)

    Susanti, Ratna F.; Kim, Jae-Duck; Kim, Jaehoon [Supercritical Fluid Research Laboratory, Clean Energy Center, Energy Division, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok-dong, Seoungbuk-gu, Seoul 136-791 (Korea); Department of Green Process and System Engineering, University of Science and Technology (UST), 113 Gwahangno, Yuseong-gu, Daejeon 305-333 (Korea); Veriansyah, Bambang [Supercritical Fluid Research Laboratory, Clean Energy Center, Energy Division, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok-dong, Seoungbuk-gu, Seoul 136-791 (Korea); Lee, Youn-Woo [School of Chemical and Biological Engineering, Seoul National University, Gwanangro 599, Gwanak-gu, Seoul 151-744 (Korea)

    2010-03-15

    A new design of supercritical water gasification system was developed to achieve high hydrogen gas yield and good gas-liquid flow stability. The apparatus consisted of a reaction zone, an insulation zone and a cooling zone that were directly connected to the reaction zone. The reactor was set up at an inclination of 75 from vertical position, and feed and water were introduced at the bottom of the reactor. The performances of this new system were investigated with gasification of isooctane at various experimental conditions - reaction temperatures of 601-676 C, residence times of 6-33 s, isooctane concentrations of 5-33 wt%, and oxidant (hydrogen peroxide) concentrations up to 4507 mmol/L without using catalysts. A significant increase in hydrogen gas yield, almost four times higher than that from the previous up-down gasifier configuration (B. Veriansyah, J. Kim, J.D. Kim, Y.W. Lee, Hydrogen Production by Gasification of Isooctane using Supercritical Water, Int. J. Green Energy. 5 (2008) 322-333) was observed with the present gasifier configuration. High hydrogen gas yield (6.13 mol/mol isooctane) was obtained at high reaction temperature of 637 C, a low feed concentration of 9.9 wt% and a long residence time of 18 s in the presence of 2701.1 mmol/L hydrogen peroxide. At this condition, the produced gases mainly consisted of hydrogen (59.5 mol%), methane (14.8 mol%) and carbon dioxide (22.0 mol%), and a small amount of carbon monoxide (1.6 mol%) and C{sub 2}-C{sub 3} species (2.1 mol%). Reaction mechanisms of supercritical water gasification of isooctane were also presented. (author)

  8. Hydrogen production from high moisture content biomass in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Antal, M.J. Jr.; Xu, X. [Univ. of Hawaii, Honolulu, HI (United States). Hawaii Natural Energy Inst.

    1998-08-01

    By mixing wood sawdust with a corn starch gel, a viscous paste can be produced that is easily delivered to a supercritical flow reactor by means of a cement pump. Mixtures of about 10 wt% wood sawdust with 3.65 wt% starch are employed in this work, which the authors estimate to cost about $0.043 per lb. Significant reductions in feed cost can be achieved by increasing the wood sawdust loading, but such an increase may require a more complex pump. When this feed is rapidly heated in a tubular flow reactor at pressures above the critical pressure of water (22 MPa), the sawdust paste vaporizes without the formation of char. A packed bed of carbon catalyst in the reactor operating at about 650 C causes the tarry vapors to react with water, producing hydrogen, carbon dioxide, and some methane with a trace of carbon monoxide. The temperature and history of the reactor`s wall influence the hydrogen-methane product equilibrium by catalyzing the methane steam reforming reaction. The water effluent from the reactor is clean. Other biomass feedstocks, such as the waste product of biodiesel production, behave similarly. Unfortunately, sewage sludge does not evidence favorable gasification characteristics and is not a promising feedstock for supercritical water gasification.

  9. Biomass gasification in supercritical water: II. Effect of catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Yanik, Jale; Ebale, Steve; Kruse, Andrea; Saglam, Mehmet; Yueksel, Mithat [Institue for Technical Chemistry, Division of Chemical-Physical Processing, Forschungszentrum Karlsruhe, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2008-09-15

    In this study, the effect of the type of catalyst on hydrothermal gasification of three specifically chosen samples of natural biomass was investigated. Biomass feedstocks, including lignocellulosic materials (cotton stalk and corncob) and the tannery waste, were gasified in supercritical water by the addition of catalyst. The catalysts used were K{sub 2}CO{sub 3}, Trona (NaHCO{sub 3}.Na{sub 2}CO{sub 3}.2H{sub 2}O), red mud (Fe-oxide containing residue from Al-production) and Raney-Ni. The gasification experiments were performed in a batch autoclave at 500 C. The amounts and compositions of the gases and the amounts of water soluble compounds from gasification were determined. The effect of catalysts on gasification varied with the type of biomass. The catalysts significantly increased the hydrogen yield by supporting the water-gas shift reaction and the methane reformation. The gasification activity of Trona was similar to that of K{sub 2}CO{sub 3}. The results indicate that iron based catalysts can also be effective in gasification of biomass. In conclusion, the supercritical water gasification of biomass by addition of red mud and Trona is said to be promising method to produce H{sub 2} from biomass efficiently similar to gasification with commercial alkali catalysts. (author)

  10. Reactions of inorganic nitrogen species in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Dell`Orco, P.C. [Texas Univ., Austin, TX (United States)

    1994-12-31

    Redox reactions of nitrate salts with NH3 and methanol were studied in near-critical and supercritical water at 350 to 530 C and constant pressure of 302 bar. Sodium nitrate decomposition reactions were investigated at similar conditions. Reactions were conducted in isothermal tubular reactor under plug flow. For kinetic modeling, nitrate and nitrite reactants were lumped into an NO{sub x}{sup -} reactant; kinetic expressions were developed for MNO{sub 3}/NH{sub 4}X and sodium nitrate decomposition reactions. The proposed elementary reaction mechanism for MNO{sub 3}/NH{sub 4}X reaction indicated that NO{sub 2} was the primary oxidizing species and that N{sub 2}/N{sub 2}O selectivities could be determined by the form of MNO{sub 3} used. This suggest a nitrogen control strategy for use in SCWO (supercritical water oxidation) processes; nitrate or NH3 could be used to remove the other, at reaction conditions far less severe than required by other methods. Reactions of nitrate with methanol indicated that nitrate was a better oxidant than oxygen in supercritical water. Nitrogen reaction products included NH3 and nitrite, while inorganic carbon was the major carbon reaction product. Analysis of excess experiments indicated that the reaction at 475 C was first order in methanol concentration and second order in NO{sub x}{sup -} concentration. In order to determine phase regimes for these reactions, solubility of sodium nitrate was determined for some 1:1 nitrate electrolytes. Solubilities were measured at 450 to 525 C, from 248 to 302 bar. A semi-empirical solvation model was shown to adequately describe the experimental sodium nitrate solubilities. Solubilities of Li, Na, and K nitrates revealed with cations with smaller ionic radii had greater solubilities with nitrate.

  11. Supercritical water gasification of biomass: an experimental study of model compounds and potential biomass feeds

    NARCIS (Netherlands)

    Chakinala, Anand Gupta

    2013-01-01

    Gasification of biomass in supercritical water is a complex process. In supercritical water ideally the biomass structure and the larger molecules are broken down into smaller, gaseous components under the influence of radicals. However, the biomass is normally fed to the system at low temperature a

  12. Lewis-acid catalyzed depolymerization of Protobind lignin in supercritical water and ethanol

    NARCIS (Netherlands)

    Guvenatam, Burcu; Heeres, Erik H.J.; Pidko, Evgeny A.; Hensen, Ernie J. M.

    2016-01-01

    The use of metal acetates, metal chlorides and metal triflates as Lewis acid catalysts for the depolymerization of soda lignin under supercritical conditions was investigated. The reactions were carried out at 400 degrees C in water and ethanol. Lignin conversion in supercritical water led to format

  13. Lewis-acid catalyzed depolymerization of Protobind lignin in supercritical water and ethanol

    NARCIS (Netherlands)

    Guvenatam, Burcu; Heeres, Erik H.J.; Pidko, Evgeny A.; Hensen, Ernie J. M.

    2016-01-01

    The use of metal acetates, metal chlorides and metal triflates as Lewis acid catalysts for the depolymerization of soda lignin under supercritical conditions was investigated. The reactions were carried out at 400 degrees C in water and ethanol. Lignin conversion in supercritical water led to

  14. Pilot-scale laboratory waste treatment by supercritical water oxidation.

    Science.gov (United States)

    Oshima, Yoshito; Hayashi, Rumiko; Yamamoto, Kazuo

    2006-01-01

    Supercritical water oxidation (SCWO) is a reaction in which organics in an aqueous solution can be oxidized by O2 to CO2 and H2O at a very high reaction rate. In 2003, The University of Tokyo constructed a facility for the SCWO process, the capacity of which is approximately 20 kl/year, for the purpose of treating organic laboratory waste. Through the operation of this facility, we have demonstrated that most of the organics in laboratory waste including halogenated organic compounds can be successfully treated without the formation of dioxines, suggesting that SCWO is useful as an alternative technology to the conventional incineration process.

  15. Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System

    OpenAIRE

    2009-01-01

    Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research...

  16. Supercritical Water as Nanomedium for Gasification of Lignite-Water Suspension

    Science.gov (United States)

    Korzh, Raisa; Bortyshevskyi, Valerii

    2016-05-01

    The gasification of an aqueous suspension of lignite from Alexandria coalfield (Ukraine) under the supercritical pressure was studied. The initial rates of the formation of hydrogen, carbon dioxide and methane were evaluated. The mutually stimulating interaction of the components of "brown coal-water-mineral matter" system was shown due to the influence of nanoscaled water medium on the formation of dipole-inductive, dispersive and ionic associates. In the temperature range of 300-450 °C, the oxygen source for gaseous products of the lignite supercritical gasification is mainly ion-associative nanoclustered water. The source of hydrogen at the subcritical temperature is the organic part of brown coal. For the supercritical water, the source of H is the nanoscale medium with ion associates. The last ones were responsible for the further transformation of coal.

  17. Supercritical Water as Nanomedium for Gasification of Lignite-Water Suspension.

    Science.gov (United States)

    Korzh, Raisa; Bortyshevskyi, Valerii

    2016-12-01

    The gasification of an aqueous suspension of lignite from Alexandria coalfield (Ukraine) under the supercritical pressure was studied. The initial rates of the formation of hydrogen, carbon dioxide and methane were evaluated. The mutually stimulating interaction of the components of "brown coal-water-mineral matter" system was shown due to the influence of nanoscaled water medium on the formation of dipole-inductive, dispersive and ionic associates. In the temperature range of 300-450 °C, the oxygen source for gaseous products of the lignite supercritical gasification is mainly ion-associative nanoclustered water. The source of hydrogen at the subcritical temperature is the organic part of brown coal. For the supercritical water, the source of H is the nanoscale medium with ion associates. The last ones were responsible for the further transformation of coal.

  18. Synthesis of niobium pentoxide nanoparticles in single-flow supercritical water

    Science.gov (United States)

    Fuchigami, Teruaki; Kakimoto, Ken-ichi

    2016-10-01

    The development of a new synthesis method is still required for very fine oxide nanoparticles. In this study, a single-flow supercritical fluid system has been developed for the synthesis of highly crystalline nanosized oxide particles. Niobium oxide particles were synthesized by single-flow supercritical water treatment, batch-type supercritical water treatment and subcritical water treatment. Niobium pentoxide nanoparticles synthesized by single-flow supercritical water treatment at 673 K, 24.5 MPa, and 15 ml min-1 flow rate had a pseudohexagonal structure. The morphology of the nanoparticle was a rod, and it has a smaller particle size and larger crystallite size than those of the oxide particles synthesized by the other methods, because the particle growth and the decomposition of surfactant were rapidly suppressed in the single-flow supercritical water treatment. The nanosized niobium pentoxide is useful as a catalyst in harsh environments and as a precursor powder of lead-free piezoelectric materials.

  19. Computational Fluid Dynamics Analysis of Canadian Supercritical Water Reactor (SCWR)

    Science.gov (United States)

    Movassat, Mohammad; Bailey, Joanne; Yetisir, Metin

    2015-11-01

    A Computational Fluid Dynamics (CFD) simulation was performed on the proposed design for the Canadian SuperCritical Water Reactor (SCWR). The proposed Canadian SCWR is a 1200 MW(e) supercritical light-water cooled nuclear reactor with pressurized fuel channels. The reactor concept uses an inlet plenum that all fuel channels are attached to and an outlet header nested inside the inlet plenum. The coolant enters the inlet plenum at 350 C and exits the outlet header at 625 C. The operating pressure is approximately 26 MPa. The high pressure and high temperature outlet conditions result in a higher electric conversion efficiency as compared to existing light water reactors. In this work, CFD simulations were performed to model fluid flow and heat transfer in the inlet plenum, outlet header, and various parts of the fuel assembly. The ANSYS Fluent solver was used for simulations. Results showed that mass flow rate distribution in fuel channels varies radially and the inner channels achieve higher outlet temperatures. At the outlet header, zones with rotational flow were formed as the fluid from 336 fuel channels merged. Results also suggested that insulation of the outlet header should be considered to reduce the thermal stresses caused by the large temperature gradients.

  20. Intermediates and kinetics for phenol gasification in supercritical water.

    Science.gov (United States)

    Huelsman, Chad M; Savage, Phillip E

    2012-02-28

    We processed phenol with supercritical water in a series of experiments, which systematically varied the temperature, water density, reactant concentration, and reaction time. Both the gas and liquid phases were analyzed post-reaction using gas chromatographic techniques, which identified and quantified the reaction intermediates and products, including H(2), CO, CH(4), and CO(2) in the gas phase and twenty different compounds--mainly polycyclic aromatic hydrocarbons--in the liquid phase. Many of these liquid phase compounds were identified for the first time and could pose environmental risks. Higher temperatures promoted gasification and resulted in a product gas rich in H(2) and CH(4) (33% and 29%, respectively, at 700 °C), but char yields increased as well. We implicated dibenzofuran and other identified phenolic dimers as precursor molecules for char formation pathways, which can be driven by free radical polymerization at high temperatures. Examination of the trends in conversion as a function of initial water and phenol concentrations revealed competing effects, and these informed the kinetic modeling of phenol disappearance. Two different reaction pathways emerged from the kinetic modeling: one in which rate ∝ [phenol](1.73)[water](-16.60) and the other in which rate ∝ [phenol](0.92)[water](1.39). These pathways may correspond to pyrolysis, which dominates when there is abundant phenol and little water, and hydrothermal reactions, which dominate in excess water. This result confirms that supercritical water gasification of phenol does not simply follow first-order kinetics, as previous efforts to model phenol disappearance had assumed.

  1. Simulations of dissociation constants in low pressure supercritical water

    Science.gov (United States)

    Halstead, S. J.; An, P.; Zhang, S.

    2014-09-01

    This article reports molecular dynamics simulations of the dissociation of hydrochloric acid and sodium hydroxide in water from ambient to supercritical temperatures at a fixed pressure of 250 atm. Corrosion of reaction vessels is known to be a serious problem of supercritical water, and acid/base dissociation can be a significant contributing factor to this. The SPC/e model was used in conjunction with solute models determined from density functional calculations and OPLSAA Lennard-Jones parameters. Radial distribution functions were calculated, and these show a significant increase in solute-solvent ordering upon forming the product ions at all temperatures. For both dissociations, rapidly decreasing entropy of reaction was found to be the controlling thermodynamic factor, and this is thought to arise due to the ions produced from dissociation maintaining a relatively high density and ordered solvation shell compared to the reactants. The change in entropy of reaction reaches a minimum at the critical temperature. The values of pKa and pKb were calculated and both increased with temperature, in qualitative agreement with other work, until a maximum value at 748 K, after which there was a slight decrease.

  2. NOMAGE4 activities 2011. Part II, Supercritical water loop

    Energy Technology Data Exchange (ETDEWEB)

    Vierstraete, P. (Ecole Nationale Superieure des mines, Paris (France)); Van Nieuwenhove, R. (Institutt for Energiteknikk, OECD Halden Reactor Project (HRP), Kjeller (Norway)); Lauritzen, B. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))

    2012-01-15

    The supercritical water reactor (SCWR) is one of the six different reactor technologies selected for research and development under the Generation IV program. Several countries have shown interest to this concept but up to now, there exist no in-pile facilities to perform the required material and fuel tests. Working on this direction, the Halden Reactor Project has started an activity in collaboration with Risoe-DTU (with Mr. Rudi Van Nieuwenhove as the project leader) to study the feasibility of a SCW loop in the Halden Reactor, which is a Heavy Boiling Water Reactor (HBWR). The ultimate goal of the project is to design a loop allowing material and fuel test studies at significant mass flow with in-core instrumentation and chemistry control possibilities. The present report focusses on the main heat exchanger required for such a loop in the Halden Reactor. The goal of this heat exchanger is to assure a supercritical flow state inside the test section (the core side) and a subcritical flow state inside the pump section. The objective is to design the heat exchanger in order to optimize the efficiency of the heat transfer and to respect several requirements as the room available inside the reactor hall, the maximal total pressure drop allowed and so on. (Author)

  3. Upgrading of crude algal bio-oil in supercritical water.

    Science.gov (United States)

    Duan, Peigao; Savage, Phillip E

    2011-01-01

    We determined the influence of a Pt/C catalyst, high-pressure H2, and pH on the upgrading of a crude algal bio-oil in supercritical water (SCW). The SCW treatment led to a product oil with a higher heating value (∼42 MJ/kg) and lower acid number than the crude bio-oil. The product oil was also lower in O and N and essentially free of sulfur. Including the Pt/C catalyst in the reactor led to a freely flowing liquid product oil with a high abundance of hydrocarbons. Overall, many of the properties of the upgraded oil obtained from catalytic treatment in SCW are similar to those of hydrocarbon fuels derived from fossil fuel resources. Thus, this work shows that the crude bio-oil from hydrothermal liquefaction of a microalga can be effectively upgraded in supercritical water in the presence of a Pt/C catalyst. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. NOMAGE4 activities 2011. Part II, Supercritical water loop

    Energy Technology Data Exchange (ETDEWEB)

    Vierstraete, P. (Ecole Nationale Superieure des mines, Paris (France)); Van Nieuwenhove, R. (Institutt for Energiteknikk, OECD Halden Reactor Project (HRP), Kjeller (Norway)); Lauritzen, B. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))

    2012-01-15

    The supercritical water reactor (SCWR) is one of the six different reactor technologies selected for research and development under the Generation IV program. Several countries have shown interest to this concept but up to now, there exist no in-pile facilities to perform the required material and fuel tests. Working on this direction, the Halden Reactor Project has started an activity in collaboration with Risoe-DTU (with Mr. Rudi Van Nieuwenhove as the project leader) to study the feasibility of a SCW loop in the Halden Reactor, which is a Heavy Boiling Water Reactor (HBWR). The ultimate goal of the project is to design a loop allowing material and fuel test studies at significant mass flow with in-core instrumentation and chemistry control possibilities. The present report focusses on the main heat exchanger required for such a loop in the Halden Reactor. The goal of this heat exchanger is to assure a supercritical flow state inside the test section (the core side) and a subcritical flow state inside the pump section. The objective is to design the heat exchanger in order to optimize the efficiency of the heat transfer and to respect several requirements as the room available inside the reactor hall, the maximal total pressure drop allowed and so on. (Author)

  5. Rapid Production of Micro- and Nano-particles Using Supercritical Water

    CERN Document Server

    Fang, Zhen

    2010-01-01

    This book shows how to use supercritical water (SCW) to synthesize nano- and micro- oxides, inorganic salts and metal particles and its recent advancement. Also polymer/biomass particles can be produced by using the method of precipitation of solutes from SCW. The particles can be used as catalysts for biomass conversions, materials in ceramics & electronic devices and composite materials. Particles are easily produced continuously in a flow reactor in short and long reaction times. Besides the synthesis process, the book also present studies of the properties of these materials. The size, siz

  6. Highly water-soluble multi-walled carbon nanotubes amine-functionalized by supercritical water oxidation.

    Science.gov (United States)

    Chun, Kyoung-Yong; Moon, In-Kyu; Han, Joo-Hee; Do, Seung-Hoe; Lee, Jin-Seo; Jeon, Seong-Yun

    2013-11-07

    Multi-walled carbon nanotubes (MWNTs) have been amine-functionalized by eco-friendly supercritical water oxidation. The facilely functionalized MWNTs have high solubility (~84 mg L(-1)) in water and 78% transmittance at 30-fold dilution. The Tyndall effect is also shown for several liquids.

  7. NOMAGE4 activities 2011, Part II, Supercritical water loop

    DEFF Research Database (Denmark)

    Vierstraete, Pierre; Van Nieuwenhove, Rudi; Lauritzen, Bent

    The supercritical water reactor (SCWR) is one of the six different reactor technologies selected for research and development under the Generation IV program. Several countries have shown interest to this concept but up to now, there exist no in-pile facilities to perform the required material...... and fuel tests. Working on this direction, the Halden Reactor Project has started an activity in collaboration with Risoe-DTU (with Mr. Rudi Van Nieuwenhove as the project leader) to study the feasibility of a SCW loop in the Halden Reactor, which is a Heavy Boiling Water Reactor (HBWR). The ultimate goal...... of the project is to design a loop allowing material and fuel test studies at significant mass flow with in-core instrumentation and chemistry control possibilities. The present report focusses on the main heat exchanger required for such a loop in the Halden Reactor. The goal of this heat exchanger is to assure...

  8. The separation of particulates from supercritical water oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Dell' Orco, P.C.; Li, L.; Gloyna, E.F.

    1991-01-01

    Small hydrocyclones with batch underflow receivers were assessed for their ability to separate micron-sized particulates from near-critical water solutions. Such particulates are expected from the effluent of a supercritical water oxidation reactor. The separation of micron-sized quartz silica, zirconia, and titania particles was investigated. A model was developed for the prediction of gross removal efficiencies as a function of a Stokes' number. Particle size distributions provided grade efficiencies for all experiments, and from these data, cut sizes were determined. Gross efficiencies up to 99% were observed for zirconia; cut sizes (d{sub 90} and d{sub 95}) near one micron were measured. 19 refs., 5 figs.

  9. Energetic approach of biomass hydrolysis in supercritical water.

    Science.gov (United States)

    Cantero, Danilo A; Vaquerizo, Luis; Mato, Fidel; Bermejo, M Dolores; Cocero, M José

    2015-03-01

    Cellulose hydrolysis can be performed in supercritical water with a high selectivity of soluble sugars. The process produces high-pressure steam that can be integrated, from an energy point of view, with the whole biomass treating process. This work investigates the integration of biomass hydrolysis reactors with commercial combined heat and power (CHP) schemes, with special attention to reactor outlet streams. The innovation developed in this work allows adequate energy integration possibilities for heating and compression by using high temperature of the flue gases and direct shaft work from the turbine. The integration of biomass hydrolysis with a CHP process allows the selective conversion of biomass into sugars with low heat requirements. Integrating these two processes, the CHP scheme yield is enhanced around 10% by injecting water in the gas turbine. Furthermore, the hydrolysis reactor can be held at 400°C and 23 MPa using only the gas turbine outlet streams.

  10. Water/oil repellent property of polyester fabrics after supercritical carbon dioxide finishing

    Directory of Open Access Journals (Sweden)

    Xu Yan-Yan

    2015-01-01

    Full Text Available The strong permeability and driving force of supercritical carbon dioxide renders it an ideal medium for fabrics finishing. This paper is to use supercritical carbon dioxide medium with a solution of organic fluorine to fabricate water/oil repellent polyester fabrics. A series of characterization methods including Fourier transform infrared spectrometry, energy dispersive spectrometry, and scanning electron microscopy were carried out to evaluate the fabrics finishing. Fourier transform infrared spectrometry showed that the transmittance peak appeared at 1202.4 and 1147.4 cm-1, indicating the presence of -CF2- group on the surface of polyester fabrics. The results of energy dispersive spectrometer and scanning electron microscopy showed that the fluorine was evenly distributed on the fibers surface. In addition, a series of physical properties were detected, including contact angel, air permeability, breaking strength, and wearing resistance. The average water and hexadecane contact angles were 147.58° and 143.78°, respectively. Compared with the initial fabrics, the treated one has little change in air permeability, while its strength increased greatly. The treated fabrics gained good water/oil repellent properties while keeping good air permeability and improving mechanical property.

  11. Improvement of dissolution property of poorly water-soluble drug by supercritical freeze granulation.

    Science.gov (United States)

    Sonoda, Ryoichi; Hara, Yuko; Iwasaki, Tomohiro; Watano, Satoru

    2009-10-01

    The dissolution property of the poorly water-soluble drug, flurbiprofen (FP) was improved by a novel supercritical freeze granulation using supercritical carbon dioxide. Supercritical freeze granulation was defined as a production method of the granulated substances by using the dry ice to generate intentionally for the rapid atomization of the supercritical carbon dioxide to the atmospheric pressure. This process utilized a rapid expansion of supercritical solutions (RESS) process with the mixture of the drug and lactose. In the supercritical freeze granulation, needle-like FP fine particles were obtained which adhered to the surface of lactose particles, which did not dissolve in supercritical carbon dioxide. The number of FP particles that adhered to the surface of particles decreased with an increase in the ratio of lactose added, leading to markedly improve the dissolution rate. This improvement was caused not only by the increase in the specific surface area but also the improvement of the dispersibility of FP in water. It is thus concluded that the supercritical freeze granulation is a useful technique to improve the dissolution property of the poorly water-soluble flurbiprofen.

  12. Glycerol and bioglycerol conversion in supercritical water for hydrogen production.

    Science.gov (United States)

    Yu-Wu, Q M; Weiss-Hortala, E; Barna, R; Boucard, H; Bulza, S

    2012-01-01

    Catalytic transesterification of vegetable oils leads to biodiesel and an alkaline feed (bioglycerol and organic residues, such as esters, alcohols. . .). The conversion ofbioglycerol into valuable organic molecules represents a sustainable industrial process leading to the valorization of a renewable organic resource. The physicochemical properties in the supercritical domain (T > 374 degrees C, P > 22.1 MPa) transform water into a solvent for organics and a reactant favouring radical reactions. In this context, the conversion ofbioglycerol in supercritical water (SCW) into platform molecules and/or high energetic gases (hydrogen, hydrocarbons) could represent an interesting valorization process. The reported research results concern the conversion of bioglycerol compared to pure glycerol. The experiments have been done in batch autoclaves (5 ml and 500 ml stirred). Solutions of pure (5 or 10 wt%) and crude (3.5 wt%) glycerol have been processed with or without catalyst (K2CO3 1.5 wt%) in the range of 450-600 degrees C. The molecular formula of bioglycerol was determined as C4.3H9.7O1.8Na0.1Si0.08. Glycerol was partially decomposed in the batch systems during the heating (42% before reaching 420 degrees C) and some intermediates (propanediol, ethylene glycol . . .) were quantified, leading to a proposition of a reaction pathway. Acrolein, a valuable platform molecule, was mainly produced in the absence of catalyst. No solid phase was recovered after SCW conversion of pure and bioglycerol in batch reactors. The optimal parameters for gasification were 600 degrees C, 25 MPa for bioglycerol and 525 degrees C, 25 MPa, for pure glycerol. In these operating conditions, 1 kg of pure or bioglycerol leads to 15 and, respectively, 10 mol of hydrogen. Supercritical water gasification of crude glycerol favoured the generation of light hydrocarbons, while pure glycerol promoted H2 production. SCW conversion of glycerol (pure and crude) allows to obtain simultaneously energetic

  13. Investigation of Supercritical Water Phenomena for Space and Extraterrestrial Application

    Science.gov (United States)

    Hicks, Michael C.; Hegde, Uday G.; Fisher, John W.

    2012-01-01

    The cost of carrying or resupplying life support resources for long duration manned space exploration missions such as a mission to Mars is prohibitive and requires the development of suitable recycling technologies. Supercritical Water Oxidation (SCWO) has been identified as an attractive candidate for these extended missions because (i) pre-drying of wet waste streams is not required, (ii) product streams are relatively benign, microbially inert, and easily reclaimed, (iii) waste conversion is complete and relatively fast, and (iv) with proper design and operation, reactions can be self-sustaining. Initial work in this area at NASA was carried out at the Ames Research Center in the 1990 s with a focus on understanding the linkages between feed stock preparation (i.e., particle size and distribution) of cellulosic based waste streams and destruction rates under a range of operating temperatures and pressures. More recently, work in SCWO research for space and extra-terrestrial application has been performed at NASA s Glenn Research Center where various investigations, with a particular focus in the gravitational effects on the thermo-physical processes occurring in the bulk medium, have been pursued. In 2010 a collaborative NASA/CNES (the French Space Agency) experiment on the critical transition of pure water was conducted in the long duration microgravity environment on the International Space Station (ISS). A follow-on experiment, to study the precipitation of salt in sub-critical, trans-critical and supercritical water is scheduled to be conducted on the ISS in 2013. This paper provides a brief history of NASA s earlier work in SCWO, discusses the potential for application of SCWO technology in extended space and extraterrestrial missions, describes related research conducted on the ISS, and provides a list of future research activities to advance this technology in both terrestrial and extra-terrestrial applications.

  14. Diffusion Limited Supercritical Water Oxidation (SCWO) in Microgravity Environments

    Science.gov (United States)

    Hicks, M. C.; Lauver, R. W.; Hegde, U. G.; Sikora, T. J.

    2006-01-01

    Tests designed to quantify the gravitational effects on thermal mixing and reactant injection in a Supercritical Water Oxidation (SCWO) reactor have recently been performed in the Zero Gravity Facility (ZGF) at NASA s Glenn Research Center. An artificial waste stream, comprising aqueous mixtures of methanol, was pressurized to approximately 250 atm and then heated to 450 C. After uniform temperatures in the reactor were verified, a controlled injection of air was initiated through a specially designed injector to simulate diffusion limited reactions typical in most continuous flow reactors. Results from a thermal mapping of the reaction zone in both 1-g and 0-g environments are compared. Additionally, results of a numerical model of the test configuration are presented to illustrate first order effects on reactant mixing and thermal transport in the absence of gravity.

  15. Study on Supercritical Water Oxidation of Oily Wastewater with Ethanol

    Directory of Open Access Journals (Sweden)

    Ma Wenbing

    2013-06-01

    Full Text Available The conventional treatments are unable to effectively remove the Chemical Oxygen Demand (COD of oily wastewater, which has seriously threatened the environment and the normal production of oil field. In this paper, an advanced method was proposed for oily wastewater treatment, Supercritical Water Oxidation (SCWO. The co-oxidative effect of ethanol on oily wastewater is characterized for the initial COD of oily wastewater (4000 mg/L and ethanol concentration (20 mg/L for a range of temperatures (390°C-450°C, a pressure of 23 Mpa for the complete combustion of both ethanol and oily wastewater. High concentrations of ethanol caused an increase in the conversion of oily wastewater at T = 450°C, p = 23 MPa and t = 9 min, the oily wastewater removal increases 8%.

  16. Corrosion of titanium in supercritical water oxidation environments

    Institute of Scientific and Technical Information of China (English)

    卢建树; 毛志远; 张九渊; 马淳安; 毛信表; 李肖华

    2002-01-01

    Supercritical water oxidation (SCWO) can effectively destroy many kinds of civilian and military wastes. The high temperature and high pressure SCWO operation conditions generate very corrosive environment that many engineering materials fail to withstand. Preliminary test shows that titanium may be a promising material in most of SCWO conditions. Commercially pure titanium is tested in four kinds of SCWO environments. Phenol, sodium dodecyl-benzosulfonate, n-amine phenol, and chlorpyrifos were chosen as typical target pollutants. The results show that titanium is only superficially attacked in the first three SCWO environments while in chlorpyrifos SCWO medium titanium is corroded. The corrosion is temperature dependent, with heavier corrosion occurring at near critical temperature. X-ray diffraction analysis shows that the corrosion products consist of titanium oxy- phosphates and titanium oxide, in which Ti5O4(PO4)4 is the main phase.

  17. Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System

    Directory of Open Access Journals (Sweden)

    Akiyoshi Hoshino

    2009-06-01

    Full Text Available Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1 system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source and keto acids (oxylic acid sources. In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life’s origin.

  18. Corrosion of combustion-synthesized {beta}-SiAlONs in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Yi Xuemei [Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628 (Japan); Yamauchi, Akira; Kurokawa, Kazuya [Center for Advanced Research of Energy and Materials, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628 (Japan); Akiyama, Tomohiro, E-mail: takiyama@eng.hokudai.ac.jp [Center for Advanced Research of Energy and Materials, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628 (Japan)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer The corrosion of {beta}-Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z}s (z = 1, 2, and 3) has been investigated in SCW under 400 Degree-Sign C/35 MPa for 100 h. Black-Right-Pointing-Pointer The corrosion behavior of these materials is studied using XRD, SEM, and EDS. Black-Right-Pointing-Pointer The reaction mechanism of {beta}-Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z}s in supercritical water is proposed. Black-Right-Pointing-Pointer The results in this study could present a valuable example for similar studies. - Abstract: The corrosion of {beta}-Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z}s (z = 1, 2, and 3) prepared by combustion synthesis (CS) followed by spark plasma sintering (SPS) was investigated in supercritical water at 400 Degree-Sign C/30 MPa for 100 h. The corrosion behavior was studied by means of gravimetry, X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive X-ray spectrometer (EDS). The mass loss and corroded layer decreased with the increasing in z value, and the results of XRD showed the oxide formed on {beta}-SiAlONs (z = 1, 2, and 3) is aluminum silicate (Al{sub 2}SiO{sub 5}). Finally, we proposed the reaction mechanism of these materials in supercritical water.

  19. Destruction of representative submarine food waste using supercritical water oxidation.

    Science.gov (United States)

    Chen, Shiying; Qu, Xuan; Zhang, Rong; Bi, Jicheng

    2015-03-01

    In this study, 13 types of organic materials were oxidized using H2O2 in a continuous flow reactor under the condition of supercritical water. The effect of the operational parameters on the conversion of total organic carbon (TOC) and total nitrogen (TN) was investigated, and the resulting quality of treated water was analyzed. It was found that these materials were easily oxidized with a TOC conversion achieving 99% at temperature of 460 °C and TN conversion reaching 94% at temperature of 500 °C. Rice decomposition was rapid, with TOC and TN decomposition rates of 99% obtained within residence of 100 s at temperature of 460 °C. At temperature of 460 °C, pressure of 24 MPa, residence time of 100 s, and excess oxygen of 100%, the quality of treated water attained levels commensurate with China's Standards for Drinking Water Quality. Reaction rate equation parameters were obtained by fitting the experimental data to the differential equation obtained using the Runge-Kutta algorithm. The decrease of the TOC in water samples exhibited reaction orders of 0.95 for the TOC concentration and 0.628 for the oxygen concentration. The activation energy was 83.018 kJ/mol.

  20. The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments

    Science.gov (United States)

    Corradini, D.; Rovere, M.; Gallo, P.

    2015-09-01

    In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones.

  1. The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments.

    Science.gov (United States)

    Corradini, D; Rovere, M; Gallo, P

    2015-09-21

    In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones.

  2. The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments

    Energy Technology Data Exchange (ETDEWEB)

    Corradini, D. [Center for Polymer Studies and Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215 (United States); Rovere, M. [Dipartimento di Matematica e Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Gallo, P., E-mail: gallop@fis.uniroma3.it [Dipartimento di Matematica e Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); INFN Sez. Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy)

    2015-09-21

    In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones.

  3. 8-Membered-ring Transition States of Water Assisted Reactions in Sub-and Super-critical Water

    Institute of Scientific and Technical Information of China (English)

    Kazuya; Kobiro; Pengyu; Wang

    2007-01-01

    1 Results Sub-and super-critical water is an attractive reaction medium for organic transformation because of their unique properties such as low viscosity,high density,low polarity,high solubility to organic compounds,and,of course,the greenness of the medium[1-3]. We report herein some unique reactions of unsaturated compounds in sub-and super-critical water.When allylbenzene was treated in supercritical water (SCW: 380 ℃,10 min,water density=0.35 g/mL),double bond migrated to give a mixture of allylb...

  4. Distributed parameter modeling and thermal analysis of a spiral water wall in a supercritical boiler

    Directory of Open Access Journals (Sweden)

    Zheng Shu

    2013-01-01

    Full Text Available In this paper, a distributed parameter model for the evaporation system of a supercritical spiral water wall boiler is developed based on a 3-D temperature field. The mathematical method is formulated for predicting the heat flux and the metal-surface temperature. The results show that the influence of the heat flux distribution is more obvious than that of the heat transfer coefficient distribution in the spiral water wall tube, and the peak of the heat transfer coefficient decreases with an increment of supercritical pressure. This distributed parameter model can be used for a 600 MW supercritical-pressure power plant.

  5. Design of a process for supercritical water desalination with zero liquid discharge

    NARCIS (Netherlands)

    Odu, Samuel Obarinu; van der Ham, Aloysius G.J.; Metz, S.; Kersten, Sascha R.A.

    2015-01-01

    Conventional desalination methods have a major drawback; the production of a liquid waste stream which must be disposed. The treatment of this waste stream has always presented technical, economic, and environmental challenges. The supercritical water desalination (SCWD) process meets these

  6. Effects of supercritical water and mechanochemical grinding treatments on physicochemical properties of chitin.

    Science.gov (United States)

    Osada, Mitsumasa; Miura, Chika; Nakagawa, Yuko S; Kaihara, Mikio; Nikaido, Mitsuru; Totani, Kazuhide

    2013-02-15

    This study examined the effects of a combined pretreatment with supercritical water and mechanochemical grinding with a ball mill on the physicochemical properties of chitin and its enzymatic degradation. Following pretreatment with a combination of supercritical water and grinding, chitin had a lower mean molecular weight, a lower crystallinity index, a lower crystallite size, greater d-spacing, weaker hydrogen bonds, and the amide group was more exposed compared with untreated chitin. These properties increased the hydrophilicity of the chitin and enhanced its enzymatic degradation. The N,N'-diacetylchitobiose (GlcNAc)(2) yield after enzymatic degradation of chitin following pretreatment with supercritical water (400 °C, 1 min) and grinding (800 rpm, 10 min) was 93%, compared with 5% without any treatment, 37% with supercritical water pretreatment alone (400 °C, 1 min), and 60% with grinding alone (800 rpm, 30 min).

  7. Assessment of black liquor gasification in supercritical water.

    Science.gov (United States)

    Sricharoenchaikul, V

    2009-01-01

    Supercritical water gasification of black liquor (waste pulping chemicals) has been examined. The aim was to evaluate the feasibility of using this technique to convert such bio-based waste to value added fuel products, as well as recovery of pulping materials. Supercritical gasification may improve overall process efficiency by eliminating the energy intensive evaporation step necessary in conventional process and product gas obtained at high pressure may be ready for utilization without any compression requirement. Appropriate operating parameters, including pressure, temperature, feed concentration, and reaction time, which would yield the highest conversion and energy efficiency were determined. Reaction was performed in a quartz capillary heated in a fluidized bed reactor. Results indicated that pressure between 220 and 400 atm has insignificant influence on the gas products and extent of carbon conversion. Increasing temperature and residence time between 375-650 degrees C and 5-120 s resulted in greater gas production, overall carbon conversion, and energy efficiency. Maximum conversion to H(2), CO, CH(4), and C(2)H(X) was achieved at the highest temperature and longest residence time tested showing an overall carbon conversion of 84.8%, gas energy content of 9.4 MJ/m(3) and energy conversion ratio of 1.2. Though higher carbon conversion and energy conversion ratio were obtained with more dilute liquor, energy content was lower than for those with higher solid contents. Due to anticipated complex design and high initial investment cost of this operation, further studies on overall feasibility should be carried out in order to identify the optimum operating window for this novel process.

  8. Development of Theoretical Methods for Predicting Solvent Effects on Reaction Rates in Supercritical Water Oxidation Processes

    Science.gov (United States)

    2007-11-02

    Tucker, manuscript in preparation. “Examination of Nonequilibrium Solvent Effects on an SN2 Reaction in Supercritical Water,” R. Behera, B...DATES COVERED Final: 7/1/99 - 12/31/02 4. TITLE AND SUBTITLE Development of theoretical methods for predicting solvent effects on reactions ...computational methods for predicting how reaction rate constants will vary with thermodynamic condition in supercritical water (SCW). Towards this

  9. Efficiency of water removal from water/ethanol mixtures using supercritical carbon dioxide

    Directory of Open Access Journals (Sweden)

    M. A. Rodrigues

    2006-06-01

    Full Text Available Techniques involving supercritical carbon dioxide have been successfully used for the formation of drug particles with controlled size distributions. However, these processes show some limitations, particularly in processing aqueous solutions. A diagram walking algorithm based on available experimental data was developed to evaluate the effect of ethanol on the efficiency of water removal processes under different process conditions. Ethanol feeding was the key parameter resulting in a tenfold increase in the efficiency of water extraction.

  10. Governing chemistry of cellulose hydrolysis in supercritical water.

    Science.gov (United States)

    Cantero, Danilo A; Bermejo, M Dolores; Cocero, M José

    2015-03-01

    At extremely low reaction times (0.02 s), cellulose was hydrolyzed in supercritical water (T=400 °C and P=25 MPa) to obtain a sugar yield higher than 95 wt%, whereas the 5-hydroxymethylfurfural (5-HMF) yield was lower than 0.01 wt %. If the reaction time was increased to 1 s, the main product was glycolaldehyde (60 wt%). Independently of the reaction time, the yield of 5-HMF was always lower than 0.01 wt%. To evaluate the reaction mechanism of biomass hydrolysis in pressurized water, several parameters (temperature, pressure, reaction time, and reaction medium) were studied for different biomasses (cellulose, glucose, fructose, and wheat bran). It was found that the H(+) and OH(-) ion concentration in the reaction medium as a result of water dissociation is the determining factor in the selectivity. The reaction of glucose isomerization to fructose and the further dehydration to 5-HMF are highly dependent on the ion concentration. By an increase in the pOH/pH value, these reactions were minimized to allow control of 5-HMF production. Under these conditions, the retroaldol condensation pathway was enhanced, instead of the isomerization/dehydration pathway. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Subcritical and supercritical water oxidation of CELSS model wastes

    Science.gov (United States)

    Takahashi, Y.; Wydeven, T.; Koo, C.

    1989-01-01

    A mixture of ammonium hydroxide with acetic acid and a slurry of human feces, urine, and wipes were used as CELSS model wastes to be wet-oxidized at temperatures from 250 to 500 C, i.e. below and above the critical point of water (374 C and 218 kg/sq cm or 21.4 MPa). The effects of oxidation temperature ( 250-500 C) and residence time (0-120 mn) on carbon and nitrogen and on metal corrosion from the reactor material were studied. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500 C, above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. A substantial amount of nitrogen remained in solution in the form of ammonia at temperatures ranging from 350 to 450 C suggesting that, around 400 C, organic carbon is completely oxidized and most of the nitrogen is retained in solution. The Hastelloy C-276 alloy reactor corroded during subcritical and supercritical water oxidation.

  12. Widom line and dynamical crossovers as routes to understand supercritical water

    Science.gov (United States)

    Gallo, P.; Corradini, D.; Rovere, M.

    2014-12-01

    Supercritical water is fundamental in many fields of applications and a precise characterization of the supercritical state is of uttermost importance for this liquid. In a fluid, when moving from the critical point into the single-phase region, the thermodynamic response functions show maxima reminiscent of the critical divergence. Here we study the thermodynamic properties of water in the supercritical region by analysing both available experimental data and our computer simulation results. We find that the lines connecting the maxima of the response functions converge on approaching the critical point in a single line, the Widom line. We further show that the Widom line coincides with a crossover from a liquid-like to a gas-like behaviour clearly visible in the transport properties. These thermodynamic and dynamic features show that the supercritical state in water is far more complex than what was so far believed, indicating a new perspective in the characterization of the thermodynamics of this state.

  13. Widom line and dynamical crossovers as routes to understand supercritical water.

    Science.gov (United States)

    Gallo, P; Corradini, D; Rovere, M

    2014-12-16

    Supercritical water is fundamental in many fields of applications and a precise characterization of the supercritical state is of uttermost importance for this liquid. In a fluid, when moving from the critical point into the single-phase region, the thermodynamic response functions show maxima reminiscent of the critical divergence. Here we study the thermodynamic properties of water in the supercritical region by analysing both available experimental data and our computer simulation results. We find that the lines connecting the maxima of the response functions converge on approaching the critical point in a single line, the Widom line. We further show that the Widom line coincides with a crossover from a liquid-like to a gas-like behaviour clearly visible in the transport properties. These thermodynamic and dynamic features show that the supercritical state in water is far more complex than what was so far believed, indicating a new perspective in the characterization of the thermodynamics of this state.

  14. EGS rock reactions with Supercritical CO2 saturated with water and water saturated with Supercritical CO2

    Energy Technology Data Exchange (ETDEWEB)

    Earl D. Mattson; Travis L. McLing; William Smith; Carl Palmer

    2013-02-01

    EGS using CO2 as a working fluid will likely involve hydro-shearing low-permeability hot rock reservoirs with a water solution. After that process, the fractures will be flushed with CO2 that is maintained under supercritical conditions (> 70 bars). Much of the injected water in the main fracture will be flushed out with the initial CO2 injection; however side fractures, micro fractures, and the lower portion of the fracture will contain connate water that will interact with the rock and the injected CO2. Dissolution/precipitation reactions in the resulting scCO2/brine/rock systems have the potential to significantly alter reservoir permeability, so it is important to understand where these precipitates form and how are they related to the evolving ‘free’ connate water in the system. To examine dissolution / precipitation behavior in such systems over time, we have conducted non-stirred batch experiments in the laboratory with pure minerals, sandstone, and basalt coupons with brine solution spiked with MnCl2 and scCO2. The coupons are exposed to liquid water saturated with scCO2 and extend above the water surface allowing the upper portion of the coupons to be exposed to scCO2 saturated with water. The coupons were subsequently analyzed using SEM to determine the location of reactions in both in and out of the liquid water. Results of these will be summarized with regard to significance for EGS with CO2 as a working fluid.

  15. Solubility of cellulose in supercritical water studied by molecular dynamics simulations.

    Science.gov (United States)

    Tolonen, Lasse K; Bergenstråhle-Wohlert, Malin; Sixta, Herbert; Wohlert, Jakob

    2015-04-02

    The insolubility of cellulose in ambient water and most aqueous systems presents a major scientific and practical challenge. Intriguingly though, the dissolution of cellulose has been reported to occur in supercritical water. In this study, cellulose solubility in ambient and supercritical water of varying density (0.2, 0.7, and 1.0 g cm(-3)) was studied by atomistic molecular dynamics simulations using the CHARMM36 force field and TIP3P water. The Gibbs energy of dissolution was determined between a nanocrystal (4 × 4 × 20 anhydroglucose residues) and a fully dissociated state using the two-phase thermodynamics model. The analysis of Gibbs energy suggested that cellulose is soluble in supercritical water at each of the studied densities and that cellulose dissolution is typically driven by the entropy gain upon the chain dissociation while simultaneously hindered by the loss of solvent entropy. Chain dissociation caused density augmentation around the cellulose chains, which improved water-water bonding in low density supercritical water whereas the opposite occurred in ambient and high density supercritical water.

  16. Hot and cold water as a supercritical solvent

    Science.gov (United States)

    Fuentevilla, Daphne Anne

    This dissertation addresses the anomalous properties of water at high temperatures near the vapor-liquid critical point and at low temperatures in the supercooled liquid region. The first part of the dissertation is concerned with the concentration dependence of the critical temperature, density, and pressure of an aqueous sodium chloride solution. Because of the practical importance of an accurate knowledge of critical parameters for industrial, geochemical, and biological applications, an empirical equation for the critical locus of aqueous sodium chloride solutions was adopted in 1999 by the International Association for the Properties of Water and Steam (IAPWS) as a guideline. However, since this original Guideline on the Critical Locus of Aqueous Solutions of Sodium Chloride was developed, two new theoretical developments occurred, motivating the first part of this dissertation. Here, I present a theory-based formulation for the critical parameters of aqueous sodium chloride solutions as a proposed replacement for the empirical formulation currently in use. This formulation has been published in the International Journal of Thermophysics and recommended by the Executive Committee of IAPWS for adoption as a Revised Guideline on the Critical Locus of Aqueous Solutions of Sodium Chloride. The second part of the dissertation addresses a new concept, considering cold water as a supercritical solvent. Based on the idea of a second, liquid-liquid, critical point in supercooled water, we explore the possibility of supercooled water as a novel supercooled solvent through the thermodynamics of critical phenomena. In 2006, I published a Physical Review letter presenting a parametric scaled equation of state for supercooled-water. Further developments based on this work led to a phenomenological mean-field "two-state" model, clarifying the nature of the phase separation in a polyamorphic single-component liquid. In this dissertation, I modify this two-state model to

  17. Effect of supercritical water shell on cavitation bubble dynamics

    Science.gov (United States)

    Shao, Wei-Hang; Chen, Wei-Zhong

    2015-05-01

    Based on reported experimental data, a new model for single cavitation bubble dynamics is proposed considering a supercritical water (SCW) shell surrounding the bubble. Theoretical investigations show that the SCW shell apparently slows down the oscillation of the bubble and cools the gas temperature inside the collapsing bubble. Furthermore, the model is simplified to a Rayleigh-Plesset-like equation for a thin SCW shell. The dependence of the bubble dynamics on the thickness and density of the SCW shell is studied. The results show the bubble dynamics depends on the thickness but is insensitive to the density of the SCW shell. The thicker the SCW shell is, the smaller are the wall velocity and the gas temperature in the bubble. In the authors’ opinion, the SCW shell works as a buffering agent. In collapsing, it is compressed to absorb a good deal of the work transformed into the bubble internal energy during bubble collapse so that it weakens the bubble oscillations. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174145 and 11334005).

  18. Supercritical water oxidation of spent extraction solvent simulants

    Institute of Scientific and Technical Information of China (English)

    王帅; 秦强; 陈土方方; 夏晓彬; 马洪军; 乔延波; 何柳斌

    2015-01-01

    The rapid development of nuclear technology has led to more liquid organic radioactive wastes. Different from the regular aqueous radioactive wastes, these liquids possess a higher hazard potential and cannot be disposed through the conventional methods due to their radioactivity and chemical nature. Spent extraction solvent is a kind of common liquid organic radioactive wastes. In this work, tri-butyl phosphate (TBP), which is more difficult to degrade in the spent extraction solvent, was used as the model compound. Influences of reaction conditions on total organic carbon (TOC) removal and the volume percentage of each gas component under supercritical water oxidation (SCWO) were studied. The SCWO behaviors of spent extraction solvent simulants were studied under the optimal conditions derived from the TBP experiment. The SCWO experiments were studied at 400–550◦C, oxidant stoichiometric ratio of 0–200%, feed concentration of 1.5%–4%and pressure of 25 MPa for 15–75 s. The results show that the TOC removal of the simulants was greater than 99.7%and CH4, H2 and CO were not detected at 550◦C, 25 MPa, oxidant stoichiometric ratio of 150%, feed concentration of 3%, and residence time of 30 s.

  19. Supercritical water oxidation of oil-based drill cuttings.

    Science.gov (United States)

    Chen, Zhong; Chen, Zeliang; Yin, Fengjun; Wang, Guangwei; Chen, Hongzhen; He, Chunlan; Xu, Yuanjian

    2017-03-09

    Oil-based drill cuttings (OBDC) are a typical hazardous solid waste that arises from drilling operations in oil and gas fields. The supercritical water oxidation (SCWO) of OBDC was comprehensively investigated in a batch reactor under the conditions of various oxygen coefficients (OC, 1.5-3.5), temperatures (T, 400-500°C) and reaction times (t, 0.5-10min). Preheating experiments indicated that most of the organic compounds in the initial OBDC sample were distributed within gaseous, oil, aqueous and solid phases, with no more than 9.8% of organic compounds converted into inorganic carbon. All tested variables, i.e., OC, T and t, positively affect the transformation of carbon compounds from the oil and solid phases to the aqueous phase and, ultimately, to CO2. Carbon monoxide is the primary stable intermediate. The total organic carbon (TOC) removal efficiency can reach up to 89.2% within 10min at 500°C. Analysis of the reaction pathways suggests both homogeneous and heterogeneous reactions exist in the reactor. The homogeneous reaction is a typical SCWO reaction that is governed by a free radical mechanism, and the heterogeneous reaction is dominated by mass transfer. The information obtained in this study is useful for further investigation and development of hydrothermal treatment procedures for OBDC.

  20. Treatment of whey wastewater by supercritical water oxidation.

    Science.gov (United States)

    Söğüt, Onur Ö; Kıpçak, Ekin; Akgün, Mesut

    2011-01-01

    Whey wastewater is a by-product of cheese industry, which causes environmental pollution problems due to its containment of heavy organic pollutants. Conventional methods such as biological treatment and physico-chemical treatment are insufficient or ineffective. In this paper, the treatment of cheese whey wastewater has been carried out by supercritical water oxidation, using hydrogen peroxide as oxidant. The reaction conditions ranged between temperatures of 400-650°C and residence times of 6-21 s under a pressure of 25 MPa. Treatment efficiencies based on TOC removal were obtained between 75.0% and 99.81%. An overall reaction rate model, which consists of the hydrothermal and the oxidation reactions, was determined for the hydrothermal decomposition of the wastewater with an activation energy of 50.022 (±1.7) kJmol(-1) and a pre-exponential factor of 107.72 (±4.1) s(-1). The oxidation reaction rate orders for the TOC and the oxidant were 1.2 (±0.4) and 0.4 (±0.1) respectively, with an activation energy of 20.337 (±0.9) kJmol(-1), and a pre-exponential factor of 1.86 (±0.5) mmol(-0.6)L(0.6)s(-1) in a 95% confidence level.

  1. Design requirements for the supercritical water oxidation test bed

    Energy Technology Data Exchange (ETDEWEB)

    Svoboda, J.M.; Valentich, D.J.

    1994-05-01

    This report describes the design requirements for the supercritical water oxidation (SCWO) test bed that will be located at the Idaho National Engineering Laboratory (INEL). The test bed will process a maximum of 50 gph of waste plus the required volume of cooling water. The test bed will evaluate the performance of a number of SCWO reactor designs. The goal of the project is to select a reactor that can be scaled up for use in a full-size waste treatment facility to process US Department of Energy mixed wastes. EG&G Idaho, Inc. will design and construct the SCWO test bed at the Water Reactor Research Test Facility (WRRTF), located in the northern region of the INEL. Private industry partners will develop and provide SCWO reactors to interface with the test bed. A number of reactor designs will be tested, including a transpiring wall, tube, and vessel-type reactor. The initial SCWO reactor evaluated will be a transpiring wall design. This design requirements report identifies parameters needed to proceed with preliminary and final design work for the SCWO test bed. A flow sheet and Process and Instrumentation Diagrams define the overall process and conditions of service and delineate equipment, piping, and instrumentation sizes and configuration Codes and standards that govern the safe engineering and design of systems and guidance that locates and interfaces test bed hardware are provided. Detailed technical requirements are addressed for design of piping, valves, instrumentation and control, vessels, tanks, pumps, electrical systems, and structural steel. The approach for conducting the preliminary and final designs and environmental and quality issues influencing the design are provided.

  2. Supercritical water oxidation for wastewater treatment Preliminary study of urea destruction

    Science.gov (United States)

    Timberlake, S. H.; Hong, G. T.; Simson, M.; Modell, M.

    1982-01-01

    Supercritical water oxidation is being investigated as a method of treating spacecraft wastewater for recycle. In this process, oxidation is conducted in an aqueous phase maintained above the critical temperature (374 C) and pressure (215 bar) of water. Organic materials are oxidized with efficiencies greater than 99.99 percent in residence times of less than 1 minute. This paper presents preliminary results for urea destruction. Above 650 C, urea can be completely broken down to nitrogen gas, carbon dioxide and water by supercritical water oxidation, without the use of a specific catalyst.

  3. Pretreatment of Corn Stover Using Supercritical CO2 with Water-Ethanol as Co-solvent

    Institute of Scientific and Technical Information of China (English)

    L(U) Huisheng; REN Miaomiao; ZHANG Minhua; CHEN Ying

    2013-01-01

    Supercritical carbon dioxide,with water-ethanol as co-solvent,was applied to pretreat corn stover to enhance its enzymatic hydrolysis.The efficiency of pretreatment was evaluated by the final reducing sugar yield obtained from the enzymatic hydrolysis of cellulose.Under the operation conditions of pretreatment pressure 15 MPa,temperature 180 ℃ and time 1 h,the optimal sugar yield of 77.8% was obtained.Scanning electron microscopy (SEM) and chemical composition analysis were applied to the pretreated corn stover.The results showed that the surface morphology and microscopic structure of pretreated corn stover were greatly changed.After the pretreatment,the contents of hemicellulose and lignin were reduced obviously.Thus more cellulose was exposed,increasing the sugar yield.

  4. Hydrogen production by catalytic gasification of cellulose in supercritical water

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cellulose,one of the important components of biomass,was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure.K2CO3 and Ca(OH)2 were selected as the catalysts (or promoters).The temperature was kept between 450℃ and 500℃ while pressure was maintained at 24-26 MPa.The reaction time was 20 min.Experimental results showed that the two catalysts had good catalytic effect and optimum amounts were observed for each catalyst.When 0.2 g K2CO3 was added,the hydrogen yield could reach 9.456 mol.kg-1 which was two times of the H2 amount produced without catalyst.When 1.6 g Ca(OH)2 was added,the H2 yield was K2CO3 as catalyst but is still 1.7 times that achieved without catalyst.Comparing with the results obtained using KaCO3 or Ca(OH)2 alone,the use of a combination of K2CO3 and Ca(OH)2 could increase the H2 yield by up to 2.5 times that without catalyst and 25% and 45% more than that obtained using K2CO3 and Ca(OH)2 alone,respectively.It was found that methane was the dominant product at relatively low temperature.When the temperature was increased,the methane reacts with water and is converted to hydrogen and carbon dioxide.

  5. Steam-Reheat Option for Supercritical-Water-Cooled Reactors

    Science.gov (United States)

    Saltanov, Eugene

    SuperCritical-Water-cooled Reactors (SCWRs) are being developed as one of the Generation-IV nuclear-reactor concepts. Main objectives of the development are to increase thermal efficiency of a Nuclear Power Plant (NPP) and to decrease capital and operational costs. The first objective can be achieved by introducing nuclear steam reheat inside a reactor and utilizing regenerative feedwater heaters. The second objective can be achieved by designing a steam cycle that closely matches that of the mature supercritical fossil-fuelled power plants. The feasibility of these objectives is discussed. As a part of this discussion, heat-transfer calculations have been performed and analyzed for SuperCritical-Water (SCW) and SuperHeated-Steam (SHS) channels of the proposed reactor concept. In the calculations a uniform and three non-uniform Axial Heat Flux Profiles (AHFPs) were considered for six different fuels (UO2, ThO 2, MOX, UC2, UC, and UN) and at average and maximum channel power. Bulk-fluid, sheath, and fuel centerline temperatures as well as the Heat Transfer Coefficient (HTC) profiles were obtained along the fuel-channel length. The HTC values are within a range of 4.7--20 kW/m2·K and 9.7--10 kW/m2·K for the SCW and SHS channels respectively. The main conclusion is that while all the mentioned fuels may be used for the SHS channel, only UC2, UC, or UN are suitable for a SCW channel, because their fuel centerline temperatures are at least 1000°C below melting point, while that of UO2, ThO2 , and MOX may reach melting point.

  6. Analyses of oxide films grown on AISI 304L stainless steel and Incoloy 800HT exposed to supercritical water environment

    Energy Technology Data Exchange (ETDEWEB)

    Fulger, Manuela, E-mail: manuela.fulger@nuclear.ro [Institute for Nuclear Research Pitesti, POB 78, Campului Street, No. 1, 115400 Mioveni (Romania); Mihalache, Maria; Ohai, Dumitru [Institute for Nuclear Research Pitesti, POB 78, Campului Street, No. 1, 115400 Mioveni (Romania); Fulger, Stefan [University Politechnica Bucharest, Splaiul Independentei Street, No. 313, Bucharest 060042 (Romania); Valeca, Serban Constantin [University of Pitesti, Targul din Vale Street, No. 1, 110040 Pitesti (Romania)

    2011-08-15

    Supercritical water (SCW) is being considered as a cooling medium for the next generation nuclear reactors because it provides high thermal efficiency and plant simplification. However, materials corrosion has been identified as a critical problem due to the oxidative nature of supercritical water. Thus, for safety using of these nuclear reactor systems a systematic study of candidate materials corrosion is needed. As in other high temperature environments, corrosion in SCW occurs by the growth of an oxide layer on the materials surface. The current work aims to evaluate oxidation behavior of AISI 304L SS and Incoloy 800HT in water at supercritical temperatures in the range 723-873 K under a pressure of 25 MPa for up to 1680 h. After exposure to deaerated supercritical water, the samples were investigated using gravimetry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). Oxide films grown on these materials have a layered structure with an outer layer consisting of a mixture of iron oxide/iron-nickel spinel oxides and an inner layer consisting of chromium oxide in the case of Incoloy 800HT and nickel-chromium spinel oxide in the case of AISI 304L SS. The mass gains for Incoloy 800HT at all temperatures were small, while comparatively with AISI 304L SS which exhibited higher oxidation rates. In the same time the results obtained by EIS indicate the best corrosion resistance of oxides grown on Incoloy 800HT surface.

  7. Current and foreseeable applications of supercritical water for energy and the environment.

    Science.gov (United States)

    Loppinet-Serani, Anne; Aymonier, Cyril; Cansell, François

    2008-01-01

    It is crucial to develop economical and energy-efficient processes for the sustainable transformation of biomass into fuels and chemicals. In this context, supercritical water biomass valorization (SCBV) processes are an alternative way to produce biogas, biofuels, and valuable chemicals. Supercritical water technology has seen much progress over the last fifteen years and an industrial application has merged: the supercritical water oxidation of wastes. The evolution from lab-scale to pilot-scale facilities has provided data on reaction mechanisms, kinetics, modeling, and reactor technology as well as an important know-how, which can now be exploited to use the reactivity in supercritical water to transform biomass into gases (CO, H(2), CO(2), CH(4), and N(2)) or into liquids (liquid fuel and valuable chemicals) with the supercritical water biomass gasification and liquefaction processes, respectively. This Review highlights the potential of SCBV processes to transform biomass into gas and liquid energy sources and highlights the developments that are still necessary to push this technology onto the market.

  8. Evaluation of supercritical water gasification and biomethanation for wet biomass utilization in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Yukihiko [Hiroshima Univ., Dept. of Mechanical System Engineering, Hiroshima (Japan)

    2002-08-01

    Two wet biomass gasification processes, supercritical water gasification and biomethanation, were evaluated from energy, environmental, and economic aspects. Gasification of 1 dry-t/d of water hyacinth was taken as a model case. Assumptions were made that system should be energetically independent, that no environmentally harmful material should be released, and that carbon dioxide should be removed from the product gas. Energy efficiency, carbon dioxide payback time, and price of the product gas were chosen as indices for energy, environmental, and economic evaluations, respectively. Under the conditions assumed here, supercritical water gasifications is evaluated to be more advantageous over biomethanation, but the cost of the product gas is still 1.86 times more expensive than city gas in Tokyo. To improve efficiency of supercritical water gasification, improvement of heat exchanger efficiency is effective. Utilization of fermentation sludge will make biomethanation much more advantageous. (Author)

  9. In-Situ Synchrotron Radiation Study of Formation and Growth of Crystalline CexZr1-xO2 Nanoparticles Synthesized in Supercritical Water

    DEFF Research Database (Denmark)

    Tyrsted, Christoffer; Becker-Christensen, Jacob; Hald, Peter

    2010-01-01

    -zirconia system, the growth of ceria and zirconia nanoparticles is fundamentally different under supercritical water conditions. For comparison, ex situ synthesis has also been performed using an in-house supercritical flow reactor. The resulting samples were analyzed using PXRD, small-angle X-ray scattering...... (SAXS), and transmission electron microscopy (TEM). The nanoparticles with x= 0, 0.2, and 0.5 have very low polydispersities. The sizes range from 4 nm to 7 nm, and the particles exhibit a reversibly pH-dependent agglomeration. Udgivelsesdato: 2010......In situ synchrotron powder X-ray diffraction (PXRD) measurements have been conducted to follow the nucleation and growth of crystalline CexZr1-xO2 nanoparticles synthesized in supercritical water with a full substitution variation (x = 0, 0.2, 0.5, 0.8, and 1.0). Direction-dependent growth curves...

  10. Stability analysis of supercritical-pressure light water-cooled reactor in constant pressure operation

    Energy Technology Data Exchange (ETDEWEB)

    Suhwan, JI; Shirahama, H.; Koshizuka, S.; Oka, Y. [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    2001-07-01

    The purpose of this study is to evaluate the thermal-hydraulic and the thermal-nuclear coupled stabilities of a supercritical pressure light water-cooled reactor. A stability analysis code at supercritical pressure is developed. Using this code, stabilities of full and partial-power reactor operating at supercritical pressure are investigated by the frequency-domain analysis. Two types of SCRs are analyzed; a supercritical light water reactor (SCLWR) and a supercritical water-cooled fast reactor (SCFR). The same stability criteria as Boiling Water Reactor are applied. The thermal-hydraulic stability of SCLWR and SCFR satisfies the criteria with a reasonable orifice loss coefficient. The decay ratio of the thermal-nuclear coupled stability in SCFR is almost zero because of a small coolant density coefficient of the fast reactor. The evaluated decay ratio of the thermal-nuclear coupled stability is 3,41 {approx} 10{sup -V} at 100% power in SCFR and 0,028 at 100% power in SCLWR. The sensitivity is investigated. It is found that the thermal-hydraulic stability is sensitive to the mass flow rate strongly and the thermal-nuclear coupled stability to the coolant density coefficient. The bottom power peak distribution makes the thermal-nuclear stability worse and the thermal-nuclear stability better. (author)

  11. Supercritical water oxidation of acrylic acid production wastewater.

    Science.gov (United States)

    Gong, Y M; Wang, S Z; Tang, X Y; Xu, D H; Ma, H H

    2014-01-01

    Supercritical water oxidation (SCWO) of wastewater from an acrylic acid manufacturing plant has been studied on a continuous flow experimental system, whose reactor was made of Hastelloy C-276. Experimental conditions included a reaction temperature (T) ranging from 673 to 773K, a residence time (t) ranging from 72.7 to 339s, a constant pressure (P) of 25 MPa and a fixed oxidation coefficient (alpha) of 2.0. Experimental results indicated that reaction temperature and residence time had significant influences on the oxidation reaction, and increasing the two operation parameters could improve both degradation of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N). The COD removal efficiency could reach up to 98.73% at 25 MPa, 773 K and 180.1 s, whereas the destruction efficiency of NH3-N was only 43.71%. We further carried out a kinetic analysis considering the induction period through free radical chain mechanism. It confirms that the power-law rate equation for COD removal was 345 exp(-52200/RT)[COD]1.98[O2]0.17 and for NH3-N removal was 500 exp(-64492.19/RT)[NH3-N]1.87 [O2]0.03. Moreover, the induction time formulations for COD and NH3-N were suspected to be exp(38250/RT)/173 and exp(55690/RT)/15231, respectively. Correspondingly, induction time changed from 2.22 to 5.38 s for COD and 0.38 to 1.38 s for NH3-N. Owing to the catalysis of reactor inner wall surface, more than 97% COD removal was achieved in all samples.

  12. Study on the Diffusion Coefficient of Sodium Chloride at Infrinite Dilution in Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    肖吉; 陆九芳; 陈健; 李以圭

    2003-01-01

    The molecular dynamics(MD) was employed to simulate the diffusion coefficient of sodium chloride at infinite dilution in supercritical water from 703.2K to 763.2K and from 30 MPa to 45 MPa ,Based on the simulated data and the Patel-Teja(PT) equation of state and the Liu-Ruckenstein equation,an equation for calculating the diffusion coefficient of NaCl at infinite dilution in supercritical water is proposed,Both the agreement between the simulated and correlated data,and that between the simulated and predicted data of diffusion coefficients for NaCl in supercritical water ranging from 703.2K to 803.2K and from 25 MPa to 50MPa show that this equation is applicable for calculation of diffusion coefficients.

  13. Rate determination of supercritical water gasification of primary sewage sludge as a replacement for anaerobic digestion.

    Science.gov (United States)

    Wilkinson, Nikolas; Wickramathilaka, Malithi; Hendry, Doug; Miller, Andrew; Espanani, Reza; Jacoby, William

    2012-11-01

    Supercritical water gasification of primary sewage sludge sampled from a local facility was undertaken at different solids content. The performance of the process was compared with the anaerobic digestion system in use at the facility where the samples were taken. The mass and composition of the vapor products documented showed that the process generates more energy per gram of feed while rapidly destroying more volatile solids relative to the anaerobic digestion process. However, the energy input requirements are greater for supercritical water gasification. This study defines parameters for a model of the gasification reaction using the power law and Arrhenius equation. The activation energy was estimated to be 15 kJ/mol, and the reaction order was estimated to be 0.586. This model allows estimation of the size of a supercritical water reactor needed to replace the anaerobic digesters that are currently used at the wastewater treatment plant.

  14. The solubilities of phosphate and sulfate salts in supercritical water

    NARCIS (Netherlands)

    Leusbrock, Ingo; Metz, Sybrand J.; Rexwinkel, Glenn; Versteeg, Geert F.

    2010-01-01

    Inorganic compounds are regularly present in aqueous streams. To understand their influence and behavior on these streams at supercritical conditions, little to no property data is available, which can be used as starting point for further research or application design. Since inorganic compounds te

  15. Implementing supercritical water oxidation technology in a lunar base environmental control/life support system

    Science.gov (United States)

    Meyer Sedej, M.

    1985-01-01

    A supercritical water oxidation system (SCWOS) offers several advantages for a lunar base environmental control/life support system (ECLSS) compared to an ECLSS based on Space Station technology. In supercritically heated water (630 K, 250 atm) organic materials mix freely with oxygen and undergo complete combustion. Inorganic salts lose solubility and precipitate out. Implementation of SCWOS can make an ECLSS more efficient and reliable by elimination of several subsystems and by reduction in potential losses of life support consumables. More complete closure of the total system reduces resupply requirements from the earth, a crucial cost item in maintaining a lunar base.

  16. A first principles approach to the electronic properties of liquid and supercritical CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Benedito J. Costa, E-mail: ben@cii.fc.ul.pt [Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal); Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto de Física da Universidade de São Paulo, CP 66318, 05314-970 São Paulo, SP (Brazil); Rivelino, Roberto [Instituto de Física da Universidade Federal da Bahia, Campus Universitário de Ondina, CEP 40210-340 Salvador, Bahia (Brazil); Coutinho, Kaline; Canuto, Sylvio [Instituto de Física da Universidade de São Paulo, CP 66318, 05314-970 São Paulo, SP (Brazil)

    2015-01-14

    The electronic absorption spectra of liquid and supercritical CO{sub 2} (scCO{sub 2}) are investigated by coupling a many-body energy decomposition scheme to configurations generated by Born-Oppenheimer molecular dynamics. A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies were calculated with time dependent density functional theory. A red-shift of ∼ 0.2 eV relative to the gas-phase monomer is observed for the first electronic absorption maximum in liquid and scCO{sub 2}. The origin of this shift, which is not very dependent on deviations from the linearity of the CO{sub 2} molecule, is mainly related to polarization effects. However, the geometry changes of the CO{sub 2} monomer induced by thermal effects and intermolecular interactions in condensed phase lead to the appearance of an average monomeric electric dipole moment 〈μ〉 = 0.26 ± 0.04 D that is practically the same at liquid and supercritical conditions. The predicted average quadrupole moment for both liquid and scCO{sub 2} is 〈Θ〉 = − 5.5 D Å, which is increased by ∼ −0.9 D Å relative to its gas-phase value. The importance of investigating the electronic properties for a better understanding of the role played by CO{sub 2} in supercritical solvation is stressed.

  17. On the gasification of wet biomass in supercritical water : over de vergassing van natte biomassa in superkritiek water

    NARCIS (Netherlands)

    Withag, J.A.M.

    2013-01-01

    Supercritical water gasification (SCWG) is a challenging thermo-chemical conversion route for wet biomass and waste streams into hydrogen and/or methane. At temperatures and pressures above the critical point the physical properties of water differ strongly from liquid water or steam. Because of the

  18. Review and proposal for heat transfer predictions at supercritical water conditions using existing correlations and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Wadim, E-mail: wadim.jaeger@kit.edu [Karlsruhe Institute of Technology, Institute for Neutron Physics and Reactor Technology, DE-76344 Eggenstein-Leopoldshafen (Germany); Sanchez Espinoza, Victor Hugo [Karlsruhe Institute of Technology, Institute for Neutron Physics and Reactor Technology, DE-76344 Eggenstein-Leopoldshafen (Germany); Hurtado, Antonio [Technical University of Dresden, Institute of Power Engineering, DE-01062 Dresden (Germany)

    2011-06-15

    Highlights: > Implementation of heat transfer correlations for supercritical water into TRACE. > Simulation of several heat transfer experiments with modified TRACE version. > Most correlations are not able to reproduce the experimental results. > Bishop, Sandberg and Tong correlation is most suitable for TRACE applications. - Abstract: This paper summarizes the activities of the TRACE code validation at the Institute for Neutron Physics and Reactor Technology related to supercritical water conditions. In particular, the providing of the thermo physical properties and its appropriate use in the wall-to-fluid heat transfer models in the frame of the TRACE code is the object of this investigation. In a first step, the thermo physical properties of the original TRACE code were modified in order to account for supercritical conditions. In a second step, existing Nusselt correlations were reviewed and implemented into TRACE and available experiments were simulated to identify the most suitable Nusselt correlation(s).

  19. Spatial and Orientational Structure of the Hydration Shell of Benzene in Sub- and Supercritical Water.

    Science.gov (United States)

    Choudhary, Ashu; Chandra, Amalendu

    2015-07-09

    The spatial and orientational structure of the solvation shell of benzene in sub- and supercritical water are investigated by means of molecular dynamics simulations. The present study reveals different local organization of water molecules at different parts of the solute. The π-hydrogen-bonding between benzene and water along the axial direction is found to exist even at supercritical conditions although to a reduced extent. The coordination number of benzene decreases substantially on increase of temperature and decrease of density. While the π-hydrogen-bonded part in the axial region shows a slight expansion, the hydrophobically solvated part in the equatorial plane shows an opposite behavior as the temperature is increased from normal to the supercritical temperature. Two other distribution functions, namely the radial/angular and spatial orientational functions (SOFs) are calculated to explore the spatially resolved angular preferences of water molecules around the benzene solute. Water molecules located axial to the benzene are found to have strong inward orientation toward the solute, however an opposite behavior is found in the equatorial region. Although at supercritical conditions, the orientational distributions of water molecules are broadened, the preferential orientations in the axial and equatorial regions remain similar to that under ambient condition on average.

  20. Water-in-Supercritical CO2 Microemulsion Stabilized by a Metal Complex.

    Science.gov (United States)

    Luo, Tian; Zhang, Jianling; Tan, Xiuniang; Liu, Chengcheng; Wu, Tianbin; Li, Wei; Sang, Xinxin; Han, Buxing; Li, Zhihong; Mo, Guang; Xing, Xueqing; Wu, Zhonghua

    2016-10-17

    Herein we propose for the first time the utilization of a metal complex for forming water-in-supercritical CO2 (scCO2 ) microemulsions. The water solubility in the metal-complex-stabilized microemulsion is significantly improved compared with the conventional water-in-scCO2 microemulsions stabilized by hydrocarbons. Such a microemulsion provides a promising route for the in situ CO2 reduction catalyzed by a metal complex at the water/scCO2 interface.

  1. Supercritical Propanol-Water Synthesis and Comprehensive Size Characterisation of Highly Crystalline anatase TiO 2 Nanoparticles

    Science.gov (United States)

    Hald, Peter; Becker, Jacob; Bremholm, Martin; Pedersen, Jan S.; Chevallier, Jacques; Iversen, Steen B.; Iversen, Bo B.

    2006-08-01

    Highly crystalline anatase TiO 2 nanoparticles have been synthesised in less than 1 min in a supercritical propanol-water mixture using a continuous flow reactor. The synthesis parameter space ( T, P, concentration) has been explored and the average particle size can be accurately controlled within 10-18 nm with narrow size distributions (2-3 nm). At subcritical conditions amorphous products are obtained, whereas a broad range of T and P in the supercritical regime gives 11-14 nm particles. At high temperature and pressure, the particles size increase to 18 nm. The nanoparticles have been extensively characterised with powder X-ray diffraction (PXRD), transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) with excellent agreement on size and size distribution parameters. The SAXS analysis suggests disk-shaped particles with diameters that are approximately double the height. For comparison, a series of conventional autoclave sol-gel syntheses have been carried out. These also produce phase-pure anatase nanoparticles, but with much broader size distributions and at much longer synthesis times (hours). The study demonstrates that synthesis in supercritical fluids is a very promising method for manipulating the size and size distribution of nanoparticles, thus removing one of the key limitations in many applications of nanomaterials.

  2. Studies on supercritical water reactor fuel assemblies using the sub-channel code COBRA-EN

    Energy Technology Data Exchange (ETDEWEB)

    Ammirabile, Luca, E-mail: luca.ammirabile@ec.europa.e [European Commission, JRC, Institute for Energy, Westerduinweg 3, 1755 LE Petten (Netherlands)

    2010-10-15

    In the Generation IV International Forum (GIF) program, the supercritical water reactor (SCWR) concept is among the six innovative reactor types selected for development in the near future. In principle the higher efficiency and better economics make the SCWR concept competitive with the current reactor design. Due to different technical challenges that, however exist, fuel assembly design represents a crucial aspect for the success of this concept. In particular large density variations, low moderation, heat transfer enhancement and deterioration have a strong effect on the core design parameters. Only a few computational tools are currently able to perform sub-channel thermal-hydraulic analysis under supercritical water conditions. At JRC-IE the existing sub-channel code COBRA-EN has been improved to work above the critical pressure of water. The water properties package of the IAPWS Industrial Formulation 1997 was integrated in COBRA-EN to compute the Thermodynamic Properties of Water and Steam. New heat transfer and pressure drop correlations more indicated for the supercritical region of water have also been incorporated in the code. As part of the efforts to appraise the new code capabilities, a code assessment was carried out on the hexagonal fuel assembly of a fast supercritical water reactor. COBRA-EN was also applied in combination with the neutronic code MCNP to investigate on the use of hydride fuel in the HPLWR supercritical water fuel assembly. The results showed that COBRA-EN was able to reproduce the results of similar studies with acceptable accuracy. Future activities will focus on the validation of the code against experimental data and the implementation of new features (counter-current moderator channel, wall, and wire-wrap models).

  3. Investigation of Mineral Transformations in Wet Supercritical CO2 by Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arey, Bruce W.; Kovarik, Libor; Wang, Zheming; Felmy, Andrew R.

    2011-10-10

    The capture and storage of carbon dioxide and other greenhouse gases in deep geologic formations represents one of the most promising options for mitigating the impacts of greenhouse gases on global warming. In this regard, mineral-fluid interactions are of prime importance since such reactions can result in the long term sequestration of CO2 by trapping in mineral phases. Recently it has been recognized that interactions with neat to water-saturated non-aqueous fluids are of prime importance in understanding mineralization reactions since the introduced CO2 is likely to contain water initially or soon after injection and the supercritical CO2 (scCO2) is less dense than the aqueous phase which can result in a buoyant scCO2 plume contacting the isolating caprock. As a result, unraveling the molecular/microscopic mechanisms of mineral transformation in neat to water saturated scCO2 has taken on an added important. In this study, we are examining the interfacial reactions of the olivine mineral forsterite (Mg2SiO4) over a range of water contents up to and including complete water saturation in scCO2. The surface precipitates that form on the reacted forsterite grains are extremely fragile and difficult to experimentally characterize. In order to address this issue we have developed experimental protocols for preparing and imaging electron-transparent samples from fragile structures. These electron-transparent samples are then examined using a combination of STEM/EDX, FIB-TEM, and helium ion microscope (HIM) imaging (Figures 1-3). This combination of capabilities has provided unique insight into the geochemical processes that occur on scCO2 reacted mineral surfaces. The experimental procedures and protocols that have been developed also have useful applications for examining fragile structures on a wide variety of materials. This research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and

  4. Molecular Dynamics Simulations of Aqueous and Confined Systems Relevant to the Supercritical Water Cooled Nuclear Reactor

    Science.gov (United States)

    Kallikragas, Dimitrios Theofanis

    Supercritical water (SCW) is the intended heat transfer fluid and potential neutron moderator in the proposed GEN-IV Supercritical Water Cooled Reactor (SCWR). The oxidative environment poses challenges in choosing appropriate design materials, and the behaviour of SCW within crevices of the passivation layer is needed for developing a corrosion control strategy to minimize corrosion. Molecular Dynamics simulations have been employed to obtain diffusion coefficients, coordination number and surface density characteristics, of water and chloride in nanometer-spaced iron hydroxide surfaces. Diffusion models for hydrazine are evaluated along with hydration data. Results demonstrate that water is more likely to accumulate on the surface at low density conditions. The effect of confinement on the water structure diminishes as the gap size increases. The diffusion coefficient of chloride decreases with larger surface spacing. Clustering of water at the surface implies that the SCWR will be most susceptible to pitting corrosion and stress corrosion cracking.

  5. Oxidation of Alloy 600 and Alloy 690: Experimentally Accelerated Study in Hydrogenated Supercritical Water

    Science.gov (United States)

    Moss, Tyler; Cao, Guoping; Was, Gary S.

    2017-04-01

    The objective of this study is to determine whether the oxidation of Alloys 600 and 690 in supercritical water occurs by the same mechanism in subcritical water. Coupons of Alloys 690 and 600 were exposed to hydrogenated subcritical and supercritical water from 633 K to 673 K (360 °C to 400 °C) and the oxidation behavior was observed. By all measures of oxide character and behavior, the oxidation process is the same above and below the supercritical line. Similar oxide morphologies, structures, and chemistries were observed for each alloy across the critical point, indicating that the oxidation mechanism is the same in both subcritical and supercritical water. Oxidation results in a multi-layer oxide structure composed of particles of NiO and NiFe2O4 formed by precipitation on the outer surface and a chromium-rich inner oxide layer formed by diffusion of oxygen to the metal-oxide interface. The inner oxide on Alloy 600 is less chromium rich than that observed on Alloy 690 and is accompanied by preferential oxidation of grain boundaries. The inner oxide on Alloy 690 initially forms by internal oxidation before a protective layer of chromium-rich MO is formed with Cr2O3 at the metal-oxide interface. Grain boundaries in Alloy 690 act as fast diffusion paths for chromium that forms a protective Cr2O3 layer at the surface, preventing grain boundary oxidation from occurring.

  6. Design of a process for supercritical water desalination with zero liquid discharge

    NARCIS (Netherlands)

    Odu, S.O.; Ham, van der A.G.J.; Metz, S.; Kersten, S.R.A.

    2015-01-01

    Conventional desalination methods have a major drawback; the production of a liquid waste stream which must be disposed. The treatment of this waste stream has always presented technical, economic, and environmental challenges. The supercritical water desalination (SCWD) process meets these challeng

  7. Sensitivity analysis of CFD code FLUENT-12 for supercritical water in vertical bare tubes

    Energy Technology Data Exchange (ETDEWEB)

    Farah, A.; Haines, P.; Harvel, G.; Pioro, I., E-mail: amjad.farah@yahoo.com, E-mail: patrickjhaines@gmail.com, E-mail: glenn.harvel@uoit.ca, E-mail: igor.pioro@uoit.ca [Univ. of Ontario Inst. of Technology, Faculty of Energy Systems and Nuclear Science,Oshawa, Ontario (Canada)

    2012-07-01

    The ability to use FLUENT 12 or other CFD software to accurately model supercritical water flow through various geometries in diabatic conditions is integral to research involving coal-fired power plants as well as Supercritical Water-cooled Reactors (SCWR). The cost and risk associated with constructing supercritical water test loops are far too great to use in a university setting. Previous work has shown that FLUENT 12, specifically realizable k-ε model, can reasonably predict the bulk and wall temperature distributions of externally heated vertical bare tubes for cases with relatively low heat and mass fluxes. However, sizeable errors were observed for other cases, often those which involved large heat fluxes that produce deteriorated heat transfer (DHT) regimes. The goal of this research is to gain a more complete understanding of how FLUENT 12 models supercritical water cases and where errors can be expected to occur. One control case is selected where expected changes in bulk and wall temperatures occur and they match empirical correlations' predictions, and the operating parameters are varied individually to gauge their effect on FLUENT's solution. The model used is the realizable k-ε, and the parameters altered are inlet pressure, mass flux, heat flux, and inlet temperature. (author)

  8. Carbon nanotubes: A promising catalyst support material for supercritical water gasification of biomass waste

    NARCIS (Netherlands)

    Vlieger, de D.J.M.; Thakur, D.B.; Lefferts, L.; Seshan, K.

    2012-01-01

    Supercritical water (SCW) as a reaction medium is especially promising for the production of renewable chemicals from biomass. Stability issues of catalyst support materials in SCW are a major setback for these reactions and hinder the further development and industrial exploitation of this techniqu

  9. One-dimensional model for heat transfer to a supercritical water flow in a tube

    NARCIS (Netherlands)

    Sallevelt, J.L.H.P.; Withag, J.A.M.; Bramer, E.A.; Brilman, D.W.F.; Brem, G.

    2012-01-01

    Heat transfer in water at supercritical pressures has been investigated numerically using a one-dimensional modeling approach. A 1D plug flow model has been developed in order to make fast predictions of the bulk-fluid temperature in a tubular flow. The chosen geometry is a vertical tube with an inn

  10. Supercritical water gasification of organic acids and alcohols: the effect of chain length

    NARCIS (Netherlands)

    Chakinala, A.G.; Kumar, S.; Kruse, A.; Kersten, S.R.A.; Swaaij, van W.P.M.; Brilman, D.W.F.

    2013-01-01

    We report the influence of the molecular structure on the gasification behaviour for a homologous series of linear chain (C1–C8) carboxylic acids and alcohols in supercritical water (600 °C and 250 bar) at two different concentrations (10 and 20 wt%). The initial concentration of carboxylic acids ha

  11. The solubility of magnesium chloride and calcium chloride in near-critical and supercritical water

    NARCIS (Netherlands)

    Leusbrock, Ingo; Metz, Sybrand J.; Rexwinkel, Glenn; Versteeg, Geert F.

    2010-01-01

    Applications using supercritical water often encounter the presence of inorganic compounds in feed streams, most often with a minor concentration. These compounds can lead to damage of the equipment via erosion, scaling and corrosion or can influence and disturb the main reaction and processes insid

  12. Oxidation of Alloy 600 and Alloy 690: Experimentally Accelerated Study in Hydrogenated Supercritical Water

    Science.gov (United States)

    Moss, Tyler; Cao, Guoping; Was, Gary S.

    2017-02-01

    The objective of this study is to determine whether the oxidation of Alloys 600 and 690 in supercritical water occurs by the same mechanism in subcritical water. Coupons of Alloys 690 and 600 were exposed to hydrogenated subcritical and supercritical water from 633 K to 673 K (360 °C to 400 °C) and the oxidation behavior was observed. By all measures of oxide character and behavior, the oxidation process is the same above and below the supercritical line. Similar oxide morphologies, structures, and chemistries were observed for each alloy across the critical point, indicating that the oxidation mechanism is the same in both subcritical and supercritical water. Oxidation results in a multi-layer oxide structure composed of particles of NiO and NiFe2O4 formed by precipitation on the outer surface and a chromium-rich inner oxide layer formed by diffusion of oxygen to the metal-oxide interface. The inner oxide on Alloy 600 is less chromium rich than that observed on Alloy 690 and is accompanied by preferential oxidation of grain boundaries. The inner oxide on Alloy 690 initially forms by internal oxidation before a protective layer of chromium-rich MO is formed with Cr2O3 at the metal-oxide interface. Grain boundaries in Alloy 690 act as fast diffusion paths for chromium that forms a protective Cr2O3 layer at the surface, preventing grain boundary oxidation from occurring.

  13. Catalytic and Non-catalytic Supercritical Water Gasification of Microalgae and Glycerol

    NARCIS (Netherlands)

    Chakinala, Anand G.; Brilman, Derk Willem Frederik; van Swaaij, Willibrordus Petrus Maria; Kersten, Sascha R.A.

    2009-01-01

    In this study, we present the gasification of microalgae (Chlorella vulgaris) and glycerol in supercritical water (SCW) using batch (quartz capillaries) and continuous flow reactors. Preliminary tests of algae gasification were done with quartz capillaries at varying operating conditions such as

  14. Catalytic reforming of glycerol in supercritical water over bimetallic Pt-Ni catalyst

    NARCIS (Netherlands)

    Chakinala, Anand G.; Swaaij, van Wim P.M.; Kersten, Sascha R.A.; Vlieger, de Dennis; Seshan, Kulathuiyer; Brilman, D.W.F. (Wim)

    2013-01-01

    Catalytic reforming of pure glycerol for the production of hydrogen at low temperature and short residence times in supercritical water was investigated using a bimetallic Pt–Ni catalyst supported on alumina. Initial tests were carried out to study the reforming activity of bimetallic Pt–Ni catalyst

  15. Supercritical CO2-based solvents in next generation micro- electronics processing

    Institute of Scientific and Technical Information of China (English)

    ZHANG XiaoGang; Keith P.JOHNSTON

    2007-01-01

    Large amount of chemicals and highly purified-water are needed in microelectronic manufacture. The ability of solutions to penetrate tiny spaces will become significantly more challenging as the feature size of semiconductor devices decreases to nanoscale dimensions and the functional complexity of integrated circuitries (ICs) ever increases. Supercritical fluids (SCFs) possess a unique combination of properties (no surface tension and gas-like viscosity) that can potentially be exploited for application in microelectronics manufacturing and processing in response to needs for material-compatible cleaning systems, small-dimension developing solvents, and low chemical-use processes. Recent microelectronics processes for cleaning and rinsing of patterned porous low-k dielectrics and drying of photoresist in CO2-based solvents are the main focus of this review. Additional topics in supercritical fluid processing include spin coating of photoresists, development with nanoscale dimensions, metal deposition and silylation.

  16. Efficient decomposition of a new fluorochemical surfactant: perfluoroalkane disulfonate to fluoride ions in subcritical and supercritical water.

    Science.gov (United States)

    Hori, Hisao; Saito, Hiroki; Sakai, Hidenori; Kitahara, Toshiyuki; Sakamoto, Takehiko

    2015-06-01

    Decomposition of (-)O3SC3F6SO3(-) in subcritical and supercritical water was investigated, and the results were compared with the results for C3F7SO3(-). This is the first report on the decomposition of perfluoroalkane disulfonates, which are being introduced in electronics industry as greener alternatives to environmentally persistent and bioaccumulative perfluoroalkyl surfactants. Addition of zerovalent iron to the reaction system dramatically increased the yield of F(-) in the reaction solution: when the reaction of (-)O3SC3F6SO3(-) was carried out in subcritical water at 350°C for 6h, the F(-) yield was 70%, which was 23times the yield without zerovalent iron. Prolonged reaction increased the F(-) formation: after 18h, the F(-) yield from the reaction of (-)O3SC3F6SO3(-) reached 81%, which was 2.1times the F(-) yield from the reaction of C3F7SO3(-). Although the reactivity of FeO toward these substrates was lower than zerovalent iron in subcritical water, the reactivity was enhanced when the reaction temperature was elevated to supercritical state, at which temperature FeO underwent in situ disproportionation to form zerovalent iron, which acted as the reducing agent. When the reaction of (-)O3SC3F6SO3(-) was carried out in the presence of FeO in supercritical water at 380°C for 18h, the F(-) yield reached 92%, which was the highest yield among tested.

  17. Electromagnetic waves and electron anisotropies downstream of supercritical interplanetary shocks

    CERN Document Server

    Wilson, L B; Szabo, A; Breneman, A; Cattell, C A; Goetz, K; Kellogg, P J; Kersten, K; Kasper, J C; Maruca, B A; Pulupa, M

    2012-01-01

    We present waveform observations of electromagnetic lower hybrid and whistler waves with f_ci 1.01. Thus, the whistler mode waves appear to be driven by a heat flux instability and cause perpendicular heating of the halo electrons. The lower hybrid waves show a much weaker correlation between \\partialB and normalized heat flux magnitude and are often observed near magnetic field gradients. A third type of event shows fluctuations consistent with a mixture of both lower hybrid and whistler mode waves. These results suggest that whistler waves may indeed be regulating the electron heat flux and the halo temperature anisotropy, which is important for theories and simulations of electron distribution evolution from the sun to the earth.

  18. Electron attachment to oxygen in supercritical hydrocarbon fluids

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, M.; Holroyd, R.A.

    1983-10-15

    The rate of attachment of electrons to oxygen was studied in methane, ethane, and propane gas above the critical temperatures up to pressures of approx.200 atm. For all three gases, the rate increases with density and levels off above N = 3 x 10/sup 21/ molecules/cm/sup 3/. For ethane, there is little or no effect of temperature on the rate between 25 and 75 /sup 0/C and the rate is independent of electric field (E) up to E/N = 1.2 x 10/sup -18/ V cm/sup 2/, but increases at higher values of E/N. To explain the results, it is suggested that the energetics of the attachment reaction change with density; i.e., the energy level of the electron in the media (V/sub 0/) and the polarization energy (P/sup -/) of O/sub 2//sup -/ change with N. The rate of attachment increases with the energy term E/sub T/ = V/sub 0/-P/sup -/+E/sub k/, where E/sub k/ is the electron kinetic energy, similar to the way the attachment rate increases with electron kinetic energy in the dilute gas.

  19. Electron attachment to oxygen in supercritical hydrocarbon fluids

    Science.gov (United States)

    Nishikawa, Masaru; Holroyd, R. A.

    1983-10-01

    The rate of attachment of electrons to oxygen was studied in methane, ethane, and propane gas above the critical temperatures up to pressures of ˜200 atm. For all three gases, the rate increases with density and levels off above N=3×1021 molecules/cm3. For ethane, there is little or no effect of temperature on the rate between 25 and 75 °C and the rate is independent of electric field (E) up to E/N=1.2×10-18 V cm2, but increases at higher values of E/N. To explain the results, it is suggested that the energetics of the attachment reaction change with density; i.e., the energy level of the electron in the media (V0) and the polarization energy (P-) of O2- change with N. The rate of attachment increases with the energy term ET=V0-P-+Ek, where Ek is the electron kinetic energy, similar to the way the attachment rate increases with electron kinetic energy in the dilute gas.

  20. Experimental investigation of heat transfer from a 2 × 2 rod bundle to supercritical pressure water

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Han [State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Bi, Qincheng, E-mail: qcbi@mail.xjtu.edu.cn [State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Linchuan; Lv, Haicai [State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Leung, Laurence K.H. [Atomic Energy of Canada Limited, Chalk River, Ont., Canada K0J 1J0 (Canada)

    2014-08-15

    Highlights: • Heat transfer of supercritical water through a 2 × 2 rod bundles is investigated. • Circumferential wall temperature distribution is obtained. • Effects of system parameters on heat transfer characteristics are analyzed. • Heat transfer correlations are compared against the rod bundle test data. - Abstract: Heat transfer experiments with supercritical pressure water flowing vertically upward through a 2 × 2 rod bundle have been performed at Xi’an Jiaotong University. A fuel-assembly simulator with four heated rods was installed inside a square channel with rounded corner. The outer diameter of each heated rod is 8 mm with an effective heated length of 600 mm. The experiments covered the pressure range of 23–28 MPa, mass-flux range of 350–1000 kg/(m{sup 2} s) and heat-flux range on the rod surface of 200–1000 kW/m{sup 2}. Heat transfer characteristics of supercritical pressure water through the bundle were examined with respect to variations of heat flux, system pressure, and mass flux. These characteristics were shown to be similar to those previously observed in tubes or annuli. The experimental data indicate a non-uniform circumferential wall-temperature distribution around the heated rod. A maximum wall temperature was observed at the surface facing the corner gap between the heated rod and the ceramic tube, while the minimum wall temperature was observed at the surface facing the center subchannel. The difference between maximum and minimum wall temperatures varies with heat flux and/or mass flux. Eight heat transfer correlations developed for supercritical water were assessed against the current set of test data. Prediction of the Jackson correlation agrees closely with the experimental Nusselt number. A new correlation has been derived based on Jackson correlation to improve the prediction accuracy of supercritical heat transfer coefficient in a 2 × 2 rod bundle.

  1. Methane and methanol oxidation in supercritical water: Chemical kinetics and hydrothermal flame studies

    Energy Technology Data Exchange (ETDEWEB)

    Steeper, R.R.

    1996-01-01

    Supercritical water oxidation (SCWO) is an emerging technology for the treatment of wastes in the presence of a large concentration of water at conditions above water`s thermodynamic critical point. A high-pressure, optically accessible reaction cell was constructed to investigate the oxidation of methane and methanol in this environment. Experiments were conducted to examine both flame and non-flame oxidation regimes. Optical access enabled the use of normal and shadowgraphy video systems for visualization, and Raman spectroscopy for in situ measurement of species concentrations. Flame experiments were performed by steadily injecting pure oxygen into supercritical mixtures of water and methane or methanol at 270 bar and at temperatures from 390 to 510{degrees}C. The experiments mapped conditions leading to the spontaneous ignition of diffusion flames in supercritical water. Above 470{degrees}C, flames spontaneously ignite in mixtures containing only 6 mole% methane or methanol. This data is relevant to the design and operation of commercial SCWO processes that may be susceptible to inadvertent flame formation. Non-flame oxidation kinetics experiments measured rates of methane oxidation in supercritical water at 270 bar and at temperatures from 390 to 442{degrees}C. The initial methane concentration was nominally 0.15 gmol/L, a level representative of commercial SCWO processes. The observed methane concentration histories were fit to a one-step reaction rate expression indicating a reaction order close to two for methane and zero for oxygen. Experiments were also conducted with varying water concentrations (0 to 8 gmol/L) while temperature and initial reactant concentrations were held constant. The rate of methane oxidation rises steadily with water concentration up to about 5 gmol/L and then abruptly falls off at higher concentrations.

  2. Oxidation behavior of ferritic-martensitic and ODS steels in supercritical water

    Science.gov (United States)

    Bischoff, Jeremy

    Ferritic-martensitic and ODS alloys are primary candidates for application as cladding and structural material in Generation IV nuclear power plants, especially the supercritical water reactor. One of the main in-service degradation mechanisms for these alloys is uniform corrosion, thus this project focuses on understanding the oxidation behavior of these alloys in the supercritical water (SCW) environment. This understanding is acquired through the analysis of the oxide microstructure using microbeam synchrotron radiation diffraction and fluorescence associated with electron microscopy (both SEM and TEM). The microbeam synchrotron radiation diffraction and fluorescence technique provides unique microstructural data of the oxide. This technique simultaneously probes elemental and phase information step by step with a sub-micron spatial resolution throughout the oxide layers. Thus we were able to locate specific phases, such as Cr2O3, at specific locations in the oxide layer, mainly the interfaces. The electron microscopy complemented this analysis by imaging the oxide layers, to yield detailed information on the oxide morphology. All the alloys studied exhibited the same three-layer structure with an outer layer containing only Fe3O4, an inner layer containing a mixture of Fe3O4 and FeCr2O 4, and a diffusion layer containing a mixture of chromium-rich precipitates (Cr2O3 and FeCr2O4) and metal grains. By analyzing samples with various exposure times, we were able to follow the evolution of the oxide microstructure with exposure time. To obtain the corroded samples, several corrosion experiments were performed: some in supercritical water (at 500°C and 600°C) and one experiment in 500°C steam. The test in steam was undertaken to obtain more data points in the kinetic curves, because we thought the corrosion in steam and supercritical water at the same temperature would result in similar kinetics. This turned out not to be the case and the samples in supercritical

  3. Extending the range of supercritical fluid chromatography by use of water-rich modifiers.

    Science.gov (United States)

    Liu, Jinchu; Regalado, Erik L; Mergelsberg, Ingrid; Welch, Christopher J

    2013-08-14

    In this study we investigate the recently reported use of water-containing modifiers for separation and purification of hydrophilic compounds by supercritical fluid chromatography. Improved peak shape is obtained for a variety of glycosides and otherwise hydrophilic compounds when 5% water is added to the methanol co-solvent used in SFC separations, and examples of the use of this approach in preparative SFC purifications are presented.

  4. Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production

    Energy Technology Data Exchange (ETDEWEB)

    Philip MacDonald; Jacopo Buongiorno; James Sterbentz; Cliff Davis; Robert Witt; Gary Was; J. McKinley; S. Teysseyre; Luca Oriani; Vefa Kucukboyaci; Lawrence Conway; N. Jonsson: Bin Liu

    2005-02-13

    The supercritical water reactor (SCWR) has been the object of interest throughout the nuclear Generation IV community because of its high potential: a simple, direct cycle, compact configuration; elimination of many traditional LWR components, operation at coolant temperatures much higher than traditional LWRs and thus high thermal efficiency. It could be said that the SWR was viewed as the water counterpart to the high temperature gas reactor.

  5. Bistable switching in supercritical n+-n-n+GaAs transferred electron devices

    DEFF Research Database (Denmark)

    Jøndrup, Peter; Jeppesen, Palle; Jeppson, Bert

    1976-01-01

    Bistable switching in supercritically doped n+-n-n+GaAs transferred electron devices (TED's) is investigated experimentally and interpreted in computer simulations, for which details of the computer program are given. Three switching modes all leading to stable anode domains are discussed, namely......: 1) cathode-triggered traveling domain; 2) cathode-triggered accumulation layer; 3) anode-triggered domain. Relative current drops up to 40 percent, and switching times down to 60 ps are obtained in low-duty-cycle pulsed experiments with threshold currents around 400 mA. Optimum device parameters...

  6. Expansion dynamics of supercritical water probed by picosecond time-resolved photoelectron spectroscopy.

    Science.gov (United States)

    Gladytz, Thomas; Abel, Bernd; Siefermann, Katrin R

    2015-02-21

    Vibrational excitation of liquid water with femtosecond laser pulses can create extreme states of water. Yet, the dynamics directly after initial sub-picosecond delocalization of molecular vibrations remain largely unclear. We study the ultrafast expansion dynamics of an accordingly prepared supercritical water phase with a picosecond time resolution. Our experimental setup combines vacuum-compatible liquid micro-jet technology and a table top High Harmonic light source driven by a femtosecond laser system. An ultrashort laser pulse centered at a wavelength of 2900 nm excites the OH-stretch vibration of water molecules in the liquid. The deposited energy corresponds to a supercritical phase with a temperature of about 1000 K and a pressure of more than 1 GPa. We use a time-delayed extreme ultraviolet pulse centered at 38.6 eV, and obtained via High Harmonic generation (HHG), to record valence band photoelectron spectra of the expanding water sample. The series of photoelectron spectra is analyzed with noise-corrected target transform fitting (cTTF), a specifically developed multivariate method. Together with a simple fluid dynamics simulation, the following picture emerges: when a supercritical phase of water expands into vacuum, temperature and density of the first few nanometers of the expanding phase drop below the critical values within a few picoseconds. This results in a supersaturated phase, in which condensation seeds form and grow from small clusters to large clusters on a 100 picosecond timescale.

  7. Combining experiment and theory to elucidate the role of supercritical water in sulfide decomposition.

    Science.gov (United States)

    Kida, Yuko; Class, Caleb A; Concepcion, Anthony J; Timko, Michael T; Green, William H

    2014-05-28

    The cleavage of C-S linkages plays a key role in fuel processing and organic geochemistry. Water is known to affect these processes, and several hypotheses have been proposed, but the mechanism has been elusive. Here we use both experiment and theory to demonstrate that supercritical water reacts with intermediates formed during alkyl sulfide decomposition. During hexyl sulfide decomposition in supercritical water, pentane and CO + CO2 were detected in addition to the expected six carbon products. A multi-step reaction sequence for hexyl sulfide reacting with supercritical water is proposed which explains the surprising products, and quantum chemical calculations provide quantitative rates that support the proposed mechanism. The key sequence is cleavage of one C-S bond to form a thioaldehyde via radical reactions, followed by a pericyclic addition of water to the C[double bond, length as m-dash]S bond to form a geminal mercaptoalcohol. The mercaptoalcohol decomposes into an aldehyde and H2S either directly or via a water-catalyzed 6-membered ring transition state. The aldehyde quickly decomposes into CO plus pentane by radical reactions. The time is ripe for quantitative modelling of organosulfur reaction kinetics based on modern quantum chemistry.

  8. Synthesis of siliceous hollow spheres with large mesopore wall structure by supercritical CO2-in-water interface templating.

    Science.gov (United States)

    Wang, Jiawei; Xia, Yongde; Wang, Wenxin; Mokaya, Robert; Poliakoff, Martyn

    2005-01-14

    Hollow silica spheres with large mesopore wall structures have been synthesized via CO(2)-in-water emulsion templating in the presence of PEO-PPO-PEO block copolymers under supercritical fluid conditions.

  9. Supercritical water oxidation: application to reduce industrial wastes. Oxidacion en agua supercritica (OASC): aplicacion a la eliminacion de residuos industriales

    Energy Technology Data Exchange (ETDEWEB)

    Cocero, M.J.; Gonzalez, R.; Fernandez-Polanco, F.

    1994-01-01

    The incineration of wastes presents many problems with environmental laws. A solution could be the Supercritic oxidation water. (SOW). This method is clean, without air pollution. The article analyzes process, depressurization, energetical approvement, and applications for wastes. (Author) 18 refs.

  10. Biomass conversions in subcritical and supercritical water: driving force, phase equilibria, and thermodynamic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Feng, W.; Kooi, H.J. van der; Swaan Arons, J. de [Physical Chemistry and Molecular Thermodynamics, Delft University of Technology, Delft (Netherlands)

    2004-07-01

    Two biomass conversion processes have been studied: hydrothermal upgrading (HTU) under subcritical water conditions; supercritical water gasification (SCWG) in supercritical water. For the design of the two biomass conversion processes, the following contributions of thermodynamics have been presented: phase behaviour and phase equilibria in the reactor and separators; indication of the favourable operation conditions and the trends in product distribution for the conversion reactions; construction of heat exchange network and exergy analysis. A wide variety of fluids have been dealt with, from small molecules to large molecules, including non-polar and polar substances. The statistical association fluids theory (SAFT) equation of state has been applied to calculate the mass distribution in different phases and to estimate the entropy and enthalpy values for different mass streams. (author)

  11. Code Development in Coupled PARCS/RELAP5 for Supercritical Water Reactor

    Directory of Open Access Journals (Sweden)

    Po Hu

    2014-01-01

    Full Text Available The new capability is added to the existing coupled code package PARCS/RELAP5, in order to analyze SCWR design under supercritical pressure with the separated water coolant and moderator channels. This expansion is carried out on both codes. In PARCS, modification is focused on extending the water property tables to supercritical pressure, modifying the variable mapping input file and related code module for processing thermal-hydraulic information from separated coolant/moderator channels, and modifying neutronics feedback module to deal with the separated coolant/moderator channels. In RELAP5, modification is focused on incorporating more accurate water properties near SCWR operation/transient pressure and temperature in the code. Confirming tests of the modifications is presented and the major analyzing results from the extended codes package are summarized.

  12. Corrosion mechanisms of candidate structural materials for supercritical water-cooled reactor

    Institute of Scientific and Technical Information of China (English)

    Lefu ZHANG; Fawen ZHU; Rui TANG

    2009-01-01

    Nickel-based alloys, austenitic stainless steel, ferritic/martensitic heat-resistant steels, and oxide dispersion strengthened steel are presently considered to be the candidate structural or fuel-cladding materials for supercritical water-cooled reactor (SCWR), one of the promising generation IV reactor for large-scale electric power production. However, corrosion and stress corrosion cracking of these candidate alloys still remain to be a major problem in the selection of nuclear fuel cladding and other structural materials, such as water rod. Survey of literature and experimental results reveal that the general corrosion mechanism of those candidate materials exhibits quite complicated mechanism in high-temperature and high-pressure supercritical water. Formation of a stable protective oxide film is the key to the best corrosion-resistant alloys. This paper focuses on the mechanism of corrosion oxide film breakdown for SCWR candidate materials.

  13. Fabrication of water-repellent cellulose fiber coated with magnetic nanoparticles under supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Xu Shengjie; Shen Danping; Wu Peiyi, E-mail: peiyiwu@fudan.edu.cn [Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials (China)

    2013-04-15

    Hematite nanoparticle-coated magnetic composite fiber was prepared in supercritical carbon dioxide (scCO{sub 2}). With the help of scCO{sub 2}, cellulose did not need to be dissolved and regenerated and it could be in any form (e.g., cotton wool, filter paper, textile, etc.). The penetrating and swelling effect of scCO{sub 2}, the slowing reaction rate of weak alkalis, and the template effect of cellulose fibers were discovered to be the key factors for the fabrication of ordered cellulose/Fe{sub 2}O{sub 3} composite fibers. The structures of the composite fibers as well as the layers of Fe{sub 2}O{sub 3} particles were characterized by means of scanning/transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman investigation. It was found that {alpha}-Fe{sub 2}O{sub 3} granules which ranged from 30 to 85 nm with average diameter around 55 nm would be generated on the surface of cellulose fibers via potassium acetate, while irregular square prisms (ranged from 200 to 600 nm) which were composed of smaller nanoparticles ({approx}10 nm) would be fabricated via urea. And, the obtained composite was highly water repellent with superparamagnetic or ferromagnetic properties.

  14. Preliminary Study on the High Efficiency Supercritical Pressure Water-Cooled Reactor for Electricity Generation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yoon Yeong; Park, Jong Kyun; Cho, Bong Hyun and others

    2006-01-15

    This research has been performed to introduce a concept of supercritical pressure water cooled reactor(SCWR) in Korea The area of research includes core conceptual design, evaluation of candidate fuel, fluid systems conceptual design with mechanical consideration, preparation of safety analysis code, and construction of supercritical pressure heat transfer test facility, SPHINX, and preliminary test. As a result of the research, a set of tools for the reactor core design has been developed and the conceptual core design with solid moderator was proposed. The direct thermodynamic cycle has been studied to find a optimum design. The safety analysis code has also been adapted to supercritical pressure condition. A supercritical pressure CO2 heat transfer test facility has been constructed and preliminary test proved the facility works as expected. The result of this project will be good basis for the participation in the international collaboration under GIF GEN-IV program and next 5-year mid and long term nuclear research program of MOST. The heat transfer test loop, SPHINX, completed as a result of this project may be used for the power cycle study as well as further heat transfer study for the various geometries.

  15. Supercritical instability of Dirac electrons in the field of two oppositely charged nuclei

    CERN Document Server

    Sobol, O O

    2016-01-01

    The Dirac equation for an electron in a finite dipole potential has been studied within the method of linear combination of atomic orbitals (LCAO). The Coulomb potential of the nuclei that compose a dipole is regularized, by considering the finite nuclear size. It is shown that if the dipole momentum reaches a certain critical value, the novel type of supercriticality occurs; namely, the wave function of the highest occupied electron bound state changes its localization from the negatively charged nucleus to the positively charged one. This phenomenon can be interpreted as a spontaneous creation of an electron-positron pair in vacuum, with each of the created particles being in the bound state with the corresponding nucleus and partially screening it.

  16. Fayalite Dissolution and Siderite Formation in Water-Saturated Supercritical CO2

    Energy Technology Data Exchange (ETDEWEB)

    Qafoku, Odeta; Kovarik, Libor; Kukkadapu, Ravi K.; Ilton, Eugene S.; Arey, Bruce W.; Tucek, Jiri; Felmy, Andrew R.

    2012-11-25

    Olivines, a significant constituent of basaltic rocks, have the potential to immobilize permanently CO2 after it is injected in the deep subsurface, due to carbonation reactions occurring between CO2 and the host rock. To investigate the reactions of fayalitic olivine with supercritical CO2 (scCO2) and formation of mineral carbonates, experiments were conducted at temperatures of 35 °C to 80 °C, 90 atm pressure and anoxic conditions. For every temperature, the dissolution of fayalite was examined both in the presence of liquid water and H2O-saturated scCO2. The experiments were conducted in a high pressure batch reactor at reaction time extending up to 85 days. The newly formed products were characterized using a comprehensive suite of bulk and surface characterization techniques X-ray diffraction, Transmission/Emission Mössbauer Spectroscopy, Scanning Electron Microscopy coupled with Focused Ion Beam, and High Resolution Transmission Electron Microscopy. Siderite with rhombohedral morphology was formed at 35 °C, 50 °C, and 80 °C in the presence of liquid water and scCO2. In H2O-saturated scCO2, the formation of siderite was confirmed only at high temperature (80 °C). Characterization of reacted samples in H2O-saturated scCO2 with high resolution TEM indicated that siderite formation initiated inside voids created during the initial steps of fayalite dissolution. Later stages of fayalite dissolution result in the formation of siderite in layered vertical structures, columns or pyramids with a rhombus base morphology.

  17. Stress corrosion cracking behavior of annealed and cold worked 316L stainless steel in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Sáez-Maderuelo, A., E-mail: alberto.saez@ciemat.es; Gómez-Briceño, D.

    2016-10-15

    Highlights: • The alloy 316L is susceptible to stress corrosion cracking in supercritical water. • The susceptibility of alloy 316L increases with temperature and plastic deformation. • Dynamic strain ageing processes may be active in the material. - Abstract: The supercritical water reactor (SCWR) is one of the more promising designs considered by the Generation IV International Forum due to its high thermal efficiency and improving security. To build this reactor, standardized structural materials used in light water reactors (LWR), like austenitic stainless steels, have been proposed. These kind of materials have shown an optimum behavior to stress corrosion cracking (SCC) under LWR conditions except when they are cold worked. It is known that physicochemical properties of water change sharply with pressure and temperature inside of the supercritical region. Owing to this situation, there are several doubts about the behavior of candidate materials like austenitic stainless steel 316L to SCC in the SCWR conditions. In this work, alloy 316L was studied in deaerated SCW at two different temperatures (400 °C and 500 °C) and at 25 MPa in order to determine how changes in this variable influence the resistance of this material to SCC. The influence of plastic deformation in the behavior of alloy 316L to SCC in SCW was also studied at both temperatures. Results obtained from these tests have shown that alloy 316L is susceptible to SCC in supercritical water reactor conditions where the susceptibility of this alloy increases with temperature. Moreover, prior plastic deformation of 316L SS increased its susceptibility to environmental cracking in SCW.

  18. Supercritical Water Mixture (SCWM) Experiment in the High Temperature Insert-Reflight (HTI-R)

    Science.gov (United States)

    Hicks, Michael C.; Hegde, Uday G.; Garrabos, Yves; Lecoutre, Carole; Zappoli, Bernard

    2013-01-01

    Current research on supercritical water processes on board the International Space Station (ISS) focuses on salt precipitation and transport in a test cell designed for supercritical water. This study, known as the Supercritical Water Mixture Experiment (SCWM) serves as a precursor experiment for developing a better understanding of inorganic salt precipitation and transport during supercritical water oxidation (SCWO) processes for the eventual application of this technology for waste management and resource reclamation in microgravity conditions. During typical SCWO reactions any inorganic salts present in the reactant stream will precipitate and begin to coat reactor surfaces and control mechanisms (e.g., valves) often severely impacting the systems performance. The SCWM experiment employs a Sample Cell Unit (SCU) filled with an aqueous solution of Na2SO4 0.5-w at the critical density and uses a refurbished High Temperature Insert, which was used in an earlier ISS experiment designed to study pure water at near-critical conditions. The insert, designated as the HTI-Reflight (HTI-R) will be deployed in the DECLIC (Device for the Study of Critical Liquids and Crystallization) Facility on the International Space Station (ISS). Objectives of the study include measurement of the shift in critical temperature due to the presence of the inorganic salt, assessment of the predominant mode of precipitation (i.e., heterogeneously on SCU surfaces or homogeneously in the bulk fluid), determination of the salt morphology including size and shapes of particulate clusters, and the determination of the dominant mode of transport of salt particles in the presence of an imposed temperature gradient. Initial results from the ISS experiments will be presented and compared to findings from laboratory experiments on the ground.

  19. Recovery of copper and lead from waste printed circuit boards by supercritical water oxidation combined with electrokinetic process.

    Science.gov (United States)

    Xiu, Fu-Rong; Zhang, Fu-Shen

    2009-06-15

    An effective and benign process for copper and lead recovery from waste printed circuit boards (PCBs) was developed. In the process, the PCBs was pre-treated in supercritical water, then subjected to electrokinetic (EK) process. Experimental results showed that supercritical water oxidation (SCWO) process was strong enough to decompose the organic compounds of PCBs, and XRD spectra indicated that copper and lead were oxidized into CuO, Cu(2)O and beta-PbO(2) in the process. The optimum SCWO treatment conditions were 60 min, 713 K, 30 MPa, and EK treatment time, constant current density were 11h, 20 mA cm(-2), respectively. The recovery percentages of copper and lead under optimum SCWO+EK treatment conditions were around 84.2% and 89.4%, respectively. In the optimized EK treatment, 74% of Cu was recovered as a deposit on the cathode with a purity of 97.6%, while Pb was recovered as concentrated solutions in either anode (23.1%) or cathode (66.3%) compartments but little was deposited on the electrodes. It is believed that the process is effective and practical for Cu and Pb recovery from waste electric and electronic equipments.

  20. Molecular dynamic simulations of iron (II) hydroxide in high temperature and supercritical water

    Science.gov (United States)

    Meng, Yuanliang

    In this study, the iron (II) hydroxide -- water system has been investigated at high temperatures by using molecular dynamics (MD) simulations. The simulation results reveal that at infinite dilution both Fe2+ cation and OH- anion have 6 water molecules within their first hydration shell and both types of ionic species experience a dramatic increase in their diffusion coefficients at near and supercritical conditions. The process of iron (II) hydroxide cluster formation has been simulated. The nano-clusters of larger sizes formed in supercritical water tend to be in an amorphous state. After having been quenched by an inert gas bath, iron (II) hydroxide nano-clusters with various structures have been produced. The geometries and associated binding energies of these species are given in detail. The vibrational spectra of iron (II) hydroxide clusters are also derived and compared with the spectrum of a bulk solid. The obtained results have a practical value for the analysis of potential corrosion products in supercritical water-cooled reactor (SCWR) which is employed in the new generation nuclear power plant design (GEN IV). This work also illustrates the process of hydrothermal synthesis of oxide nano-particles.

  1. Modeling of biomass to hydrogen via the supercritical water pyrolysis process

    Energy Technology Data Exchange (ETDEWEB)

    Divilio, R.J. [Combustion Systems Inc., Silver Spring, MD (United States)

    1998-08-01

    A heat transfer model has been developed to predict the temperature profile inside the University of Hawaii`s Supercritical Water Reactor. A series of heat transfer tests were conducted on the University of Hawaii`s apparatus to calibrate the model. Results of the model simulations are shown for several of the heat transfer tests. Tests with corn starch and wood pastes indicated that there are substantial differences between the thermal properties of the paste compared to pure water, particularly near the pseudo critical temperature. The assumption of constant thermal diffusivity in the temperature range of 250 to 450 C gave a reasonable prediction of the reactor temperatures when paste is being fed. A literature review is presented for pyrolysis of biomass in water at elevated temperatures up to the supercritical range. Based on this review, a global reaction mechanism is proposed. Equilibrium calculations were performed on the test results from the University of Hawaii`s Supercritical Water Reactor when corn starch and corn starch and wood pastes were being fed. The calculations indicate that the data from the reactor falls both below and above the equilibrium hydrogen concentrations depending on test conditions. The data also indicates that faster heating rates may be beneficial to the hydrogen yield. Equilibrium calculations were also performed to examine the impact of wood concentration on the gas mixtures produced. This calculation showed that increasing wood concentrations favors the formation of methane at the expense of hydrogen.

  2. Hydrothermal decomposition of pentachlorophenol in subcritical and supercritical water with sodium hydroxide addition

    Institute of Scientific and Technical Information of China (English)

    PRABOWO Benedictus; VERIANSYAH Bambang; KIM Jae-Duck

    2007-01-01

    Hydrothermal decomposition of pentachlorophenol (PCP), (C6HCl5O), as the probable human carcinogen, was investigated in a tubular reactor under subcritical and supercritical water with sodium hydroxide (NaOH) addition. The experiments were conducted at a temperature of 300-420℃ and a fixed pressure of 25 MPa, with a residence time that ranged from 10 s to 70 s. Under the reaction conditions, the initial PCP concentrations were varied from 0.25 to 1.39 mmol/L and the NaOH concentrations were varied from 2.5 to 25 times of the concentrations of PCP. The result of this study showed that PCP conversion in supercritical water is highly dependent on the reaction temperature, residence times, and NaOH concentration. PCP conversion in subcritical water is, however, only dependent on reaction temperature. NaOH concentration and residence times were found to have little effect on PCP conversion in subcritical condition. It was found that NaOH concentration affected the dechlorinations of PCP in the supercritical water. The intermediates detected products were proposed to be tetrachlorophenol and trichlorophenol, respectively.

  3. Destruction of polyphasic systems in supercritical water reaction media; Etude de la destruction de systemes polyphasiques en milieu eau supercritique

    Energy Technology Data Exchange (ETDEWEB)

    Leybros, A.

    2009-12-15

    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)

  4. Advanced oxidation of water soluble organics (WSO) from near- and supercritical hydrothermal liquefaction (HTL) of biomass

    DEFF Research Database (Denmark)

    Arturi, Katarzyna Ratajczyk; Nielsen, Rudi Pankratz; Muff, Jens

    . Numerous applications of HTL for conversion of wastes with high water contents (sewage, manure, or lipid-rich algae cultivated on wastewater nutrients) to high-value drop-in biofuels have been studied. The main bulk of the research focuses on the optimization of the biocrude production, while management......The challenges involving procuring the necessary water and energy resources for the future generations are partially entwined. An example of the close water-energy dependency is the production of drop-in biofuels by hydrothermal liquefaction (HTL) of biomass in near- and supercritical water...

  5. Direct Conversion of Cellulose into Ethyl Lactate in Supercritical Ethanol-Water Solutions.

    Science.gov (United States)

    Yang, Lisha; Yang, Xiaokun; Tian, Elli; Lin, Hongfei

    2016-01-08

    Biomass-derived ethyl lactate is a green solvent with a growing market as the replacement for petroleum-derived toxic organic solvents. Here we report, for the first time, the production of ethyl lactate directly from cellulose with the mesoporous Zr-SBA-15 silicate catalyst in a supercritical mixture of ethanol and water. The relatively strong Lewis and weak Brønsted acid sites on the catalyst, as well as the surface hydrophobicity, were beneficial to the reaction and led to synergy during consecutive reactions, such as depolymerization, retro-aldol condensation, and esterification. Under the optimum reaction conditions, ∼33 % yield of ethyl lactate was produced from cellulose with the Zr-SBA-15 catalyst at 260 °C in supercritical 95:5 (w/w) ethanol/water.

  6. Solvation structures and dynamics of alkaline earth metal halides in supercritical water: A molecular dynamics study

    Science.gov (United States)

    Keshri, Sonanki; Mandal, Ratnamala; Tembe, B. L.

    2016-09-01

    Constrained molecular dynamics simulations of alkaline earth metal halides have been carried out to investigate their structural and dynamical properties in supercritical water. Potentials of mean force (PMFs) for all the alkaline earth metal halides in supercritical water have been computed. Contact ion pairs (CIPs) are found to be more stable than all other configurations of the ion pairs except for MgI2 where solvent shared ion pair (SShIP) is more stable than the CIP. There is hardly any difference in the PMFs between the M2+ (M = Mg, Ca, Sr, Ba) and the X- (X = F, Cl, Br, I) ions whether the second X- ion is present in the first coordination shell of the M2+ ion or not. The solvent molecules in the solvation shells diffuse at a much slower rate compared to the bulk. Orientational distribution functions of solvent molecules are sharper for smaller ions.

  7. Prospects for development of an innovative water-cooled nuclear reactor for supercritical parameters of coolant

    Science.gov (United States)

    Kalyakin, S. G.; Kirillov, P. L.; Baranaev, Yu. D.; Glebov, A. P.; Bogoslovskaya, G. P.; Nikitenko, M. P.; Makhin, V. M.; Churkin, A. N.

    2014-08-01

    The state of nuclear power engineering as of February 1, 2014 and the accomplished elaborations of a supercritical-pressure water-cooled reactor are briefly reviewed, and the prospects of this new project are discussed based on this review. The new project rests on the experience gained from the development and operation of stationary water-cooled reactor plants, including VVERs, PWRs, BWRs, and RBMKs (their combined service life totals more than 15 000 reactor-years), and long-term experience gained around the world with operation of thermal power plants the turbines of which are driven by steam with supercritical and ultrasupercritical parameters. The advantages of such reactor are pointed out together with the scientific-technical problems that need to be solved during further development of such installations. The knowledge gained for the last decade makes it possible to refine the concept and to commence the work on designing an experimental small-capacity reactor.

  8. Explorative catalyst screening studies on reforming of glycerol in supercritical water

    NARCIS (Netherlands)

    van Bennekom, J. G.; Kirillov, V. A.; Amosov, Y. I.; Krieger, T.; Venderbosch, R. H.; Assink, D.; Lemmens, K. P. J.; Heeres, H. J.

    2012-01-01

    An explorative screening study with Pt/CeZrO2, Ni/ZrO2. Ni/CaO-6Al(2)O(3), NiCu/CeZrO2, and a CuZn alloy was carried out to investigate the influence of different catalysts on the carbon-to-gas efficiency and gas composition in the reforming of glycerol in supercritical water. Experiments were condu

  9. Kinetic analysis for destruction of municipal sewage sludge and alcohol distillery wastewater by supercritical water oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Motonobu; Nada, Takatsugu; Kodama, Akio; Hirose, Tsutomu [Kumamoto Univ. (Japan). Dept. of Applied Chemistry and Biochemistry

    1999-05-01

    Supercritical water oxidation was applied to the destruction of municipal excess sewage sludge and alcohol distillery wastewater of molasses. The reaction was carried out in a batch reactor with hydrogen peroxide as an oxidant in the temperature range 673--773 K. Total organic carbon was measured as a function of reaction time. The dynamic data were analyzed by a first-order reaction model. The reaction rate constant coincides with those reported in the literature.

  10. Hydrogen production from coal gasification in supercritical water with a continuous flowing system

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yongliang; Guo, Liejin; Zhang, Ximin; Jin, Hui; Lu, Youjun [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

    2010-04-15

    The technology of supercritical water gasification can convert coal to hydrogen-rich gaseous product efficiently and cleanly. A novel continuous-flow system for coal gasification in supercritical water was developed successfully in State Key Laboratory of Multiphase Flow in Power Engineering (SKLMF). The experimental device was designed for the temperature up to 800 C and the pressure up to 30 MPa. The gasification characteristics of coal were investigated within the experimental condition range of temperature at 650-800 C, pressure at 23-27 MPa and flow rate from 3 kg h{sup -1} to 7 kg h{sup -1}. K{sub 2}CO{sub 3} and Raney-Ni were used as catalyst and H{sub 2}O{sub 2} as oxidant. The effects of main operation parameters (temperature, pressure, flow rate, catalyst, oxidant, concentration of coal slurry) upon gasification were carried out. The slurry of 16 wt% coal + 1.5 wt% CMC was successfully transported into the reactor and continuously gasified in supercritical water in the system. The hydrogen fraction reached up to 72.85%. The experimental results demonstrate the bright future of efficient and clean conversion of coal. (author)

  11. Experimental Investigation on Flow-Induced Vibration of Fuel Rods in Supercritical Water Loop

    Directory of Open Access Journals (Sweden)

    Licun Wu

    2014-01-01

    Full Text Available The supercritical water-cooled reactor (SCWR is one of the most promising Generation IV reactors. In order to make the fuel qualification test for SCWR, a research plan is proposed to test a small scale fuel assembly in a supercritical water loop. To ensure the structure safety of fuel assembly in the loop, a flow-induced vibration experiment was carried out to investigate the vibration behavior of fuel rods, especially the vibration caused by leakage flow. From the experiment result, it can be found that: the vibration of rods is mainly caused by turbulence when flow rate is low. However, the effects of leakage flow become obvious as flow rate increases, which could changes the distribution of vibrational energy in spectrum, increasing the vibrational energy in high-frequency band. That is detrimental to the structure safety of fuel rods. Therefore, it is more reasonable to improve the design by using the spacers with blind hole, which can eliminate the leakage flow, to assemble the fuel rods in supercritical water loop. On the other hand, the experimental result could provide a benchmark for the theoretical studies to validate the applicability of boundary condition set for the leakage-flow-induced vibration.

  12. The effect of oxidation treatment with supercritical water/hydrogen peroxide system on intersurface performance for polyacrylonitrile-based carbon fibers

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Linghui; Fan, Dapeng; Zhang, Chunhua; Jiang, Zaixing [School of Chemical Engineering and Technology, Harbin Institute of Technology, P.O. Box 410, Harbin 150001 (China); Huang, Yudong, E-mail: ydhuang.hit1@yahoo.com.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, P.O. Box 410, Harbin 150001 (China)

    2013-05-15

    In order to improve the interfacial properties between carbon fibers and epoxy matrix, supercritical water and hydrogen peroxide were used as oxidation medium for the oxidation treatment for carbon fibers. Analysis results of X-ray photoelectron spectroscopy suggest that the oxygen content on the carbon fibers’ surfaces increases by these oxidation treatments. Scanning electron microscope and atomic force microscopy images indicate that the surface appearance of oxidized carbon fibers obviously changed. The maximal interlaminar shear strength and interface shear strength of carbon fiber/epoxy resin composite in which the fibers were treated by the supercritical water and hydrogen peroxide systems reaches 70.46 MPa and 106.66 MPa, increases by 13.4% and 29.6% respectively compared with untreated carbon fibers.

  13. The effect of oxidation treatment with supercritical water/hydrogen peroxide system on intersurface performance for polyacrylonitrile-based carbon fibers

    Science.gov (United States)

    Meng, Linghui; Fan, Dapeng; Zhang, Chunhua; Jiang, Zaixing; Huang, Yudong

    2013-05-01

    In order to improve the interfacial properties between carbon fibers and epoxy matrix, supercritical water and hydrogen peroxide were used as oxidation medium for the oxidation treatment for carbon fibers. Analysis results of X-ray photoelectron spectroscopy suggest that the oxygen content on the carbon fibers' surfaces increases by these oxidation treatments. Scanning electron microscope and atomic force microscopy images indicate that the surface appearance of oxidized carbon fibers obviously changed. The maximal interlaminar shear strength and interface shear strength of carbon fiber/epoxy resin composite in which the fibers were treated by the supercritical water and hydrogen peroxide systems reaches 70.46 MPa and 106.66 MPa, increases by 13.4% and 29.6% respectively compared with untreated carbon fibers.

  14. Supercritical CO{sub 2} fluid for chip resistor cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.W.; Chang, R.T.; Lin, W.K.; Lin, R.D.; Liang, M.T.; Yang, J.F.; Wang, J.B.

    1999-09-01

    The cleaning ability of supercritical CO{sub 2} was examined on chip resistors. Extraction analyses were made by atomic absorption spectroscopy and the extent of surface cleaning observed by scanning electron microscopy. Experimental results showed that the flow-cleaning process of supercritical CO{sub 2} possessed the advantages of having a superior cleaning ability and permitting a nondrying step. These characteristics strongly suggest that supercritical CO{sub 2} is a superior alternative to the traditional deionized water used in rinsing chip resistors. Moreover, a higher pressure and temperature can benefit the cleaning ability of this novel supercritical CO{sub 2} cleaning technique.

  15. Gasification Mechanism of Carbon with Supercritical Water at Very High Pressures: Effects on H2 Production.

    Science.gov (United States)

    Martin-Sanchez, Nicolas; Salvador, Francisco; Sanchez-Montero, M Jesus; Izquierdo, Carmen

    2014-08-07

    The scarce data concerning the gasification of carbonaceous solids with supercritical water (SCW) suggest the great potential of this method to produce a valuable green fuel such as H2. However, the extraordinary properties of SCW have not been properly applied to H2 production because the mechanism that governs gasification under these conditions remains unclear. Here, we present a study in which this reaction is explored within the largest pressure range ever assayed in this field, from 1 to 1000 bar. The amplitude of the experimental conditions investigated highlights the various pathways that govern gasification with steam and SCW. Under supercritical conditions, the clusters formed around the superficial groups of the solid reduce the energetic requirements for gasification and generate CO2 as a primary product of the reaction. Consequently, gasification with SCW is significantly faster than that using steam, and the produced gases are richer and more appropriate to obtain pure H2.

  16. Near-critical and supercritical water and their applications for biorefineries

    CERN Document Server

    Fang, Zhen

    2014-01-01

    The book provides fundamental chemistry and properties of near-critical water (NCW) and supercritical water (SCW), criteria and challenges/solutions in reactor design for NCW and SCW processes, and up-to-date reviews and practice of a wide range of their applications in bio refineries including: production of hydrochars from biomass, SCW oxidation (SCWO) for waste treatment, SCW gasification (SCWG) of biomass and waste for hydrogen and methane production, hydrothermal liquefaction of biomass, production of chemicals and SCWO of biofuels for energy. It also presents techno-economic analysis of

  17. Modified Korteweg-de Vries solitons at supercritical densities in two-electron temperature plasmas

    CERN Document Server

    Verheest, Frank; Hereman, Willy A

    2016-01-01

    The supercritical composition of a plasma model with cold positive ions in the presence of a two-temperature electron population is investigated, initially by a reductive perturbation approach, under the combined requirements that there be neither quadratic nor cubic nonlinearities in the evolution equation. This leads to a unique choice for the set of compositional parameters and a modified Korteweg-de Vries equation (mKdV) with a quartic nonlinear term. The conclusions about its one-soliton solution and integrability will also be valid for more complicated plasma compositions. Only three polynomial conservation laws can be obtained. The mKdV equation with quartic nonlinearity is not completely integrable, thus precluding the existence of multi-soliton solutions. Next, the full Sagdeev pseudopotential method has been applied and this allows for a detailed comparison with the reductive perturbation results. This comparison shows that the mKdV solitons have slightly larger amplitudes and widths than those obta...

  18. Direct liquefaction of Dunaliella tertiolecta for bio-oil in sub/supercritical ethanol-water.

    Science.gov (United States)

    Chen, Yu; Wu, Yulong; Zhang, Peiling; Hua, Derun; Yang, Mingde; Li, Chun; Chen, Zhen; Liu, Ji

    2012-11-01

    This paper presents bio-oil preparation by direct liquefaction of Dunaliella tertiolecta (D. tertiolecta) with sub/supercritical ethanol-water as the medium in a batch autoclave with high temperature and high pressure. The results indicated that ethanol and water showed synergistic effects on direct liquefaction of D. tertiolecta. The maximum bio-oil yield was 64.68%, with an optimal D. tertiolecta conversion of 98.24% in sub/supercritical ethanol-water. The detailed chemical compositional analysis of the bio-oil was performed using an EA, FT-IR, and GC-MS. The empirical formulas of the bio-oil obtained using the ethanol-water co-solvent (40%, v/v) and sole water as the reaction medium were CH(1.52)O(0.14)N(0.06) and CH(1.43)O(0.23)N(0.09), with calorific values of 34.96 and 29.80 MJ kg(-1), respectively. XPS and SEM results showed that ethanol-water is a very effective reaction medium in the liquefaction. A plausible reaction mechanism of the main chemical component in D. tertiolecta is proposed based on our results and the literatures.

  19. Van der Waals effects in ab initio water at ambient and supercritical conditions.

    Science.gov (United States)

    Jonchiere, Romain; Seitsonen, Ari P; Ferlat, Guillaume; Saitta, A Marco; Vuilleumier, Rodolphe

    2011-10-21

    Density functional theory (DFT) within the generalized gradient approximation (GGA) is known to poorly reproduce the experimental properties of liquid water. The poor description of the dispersion forces in the exchange correlation functionals is one of the possible causes. Recent studies have demonstrated an improvement in the simulated properties when they are taken into account. We present here a study of the effects on liquid water of the recently proposed semi-empirical correction of Grimme et al. [J. Chem. Phys. 132, 154104 (2010)]. The difference between standard and corrected DFT-GGA simulations is rationalized with a detailed analysis upon modifying an accurate parameterised potential. This allows an estimate of the typical range of dispersion forces in water. We also show that the structure and diffusivity of ambient-like liquid water are sensitive to the fifth neighbor position, thus highlighting the key role played by this neighbor. Our study is extended to water at supercritical conditions, where experimental and theoretical results are much more scarce. We show that the semi-empirical correction by Grimme et al. improves significantly, although somewhat counter-intuitively, both the structural and the dynamical description of supercritical water.

  20. Numerical Comparison of Thermalhydraulic Aspects of Supercritical Carbon Dioxide and Subcritical Water-Based Natural Circulation Loop

    Directory of Open Access Journals (Sweden)

    Milan Krishna Singha Sarkar

    2017-02-01

    Full Text Available Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

  1. Numerical comparison of thermal hydraulic aspects of supercritical carbon dioxide and subcritical water-based natural circulation loop

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Milan Krishna Singhar; Basu, Dipankar Narayan [Dept. of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati (India)

    2017-02-15

    Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

  2. Experimental study on the minimum drag coefficient of supercritical pressure water in horizontal tubes

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Xianliang, E-mail: xianlianglei@mail.xjtu.edu.cn; Li, Huixiong; Guo, YuMeng; Zhang, Qing; Zhang, Weiqiang; Zhang, Qian

    2016-05-15

    Highlights: • The minimum drag coefficient phenomenon (MDC) has been observed and further investigated. • Effects of heat flux, mass flux and pressure to MDC have been discussed. • A series of comparisons between existing correlations and data have been conducted. • Two correlations of drag coefficient are proposed for isothermal and nonisothermal flow. - Abstract: Hydraulic resistance and its components are of great importance for understanding the turbulence nature of supercritical fluid and establishing prediction methods. Under supercritical pressures, the hydraulic resistance of the fluid exhibits a “pit” in the regions near its pseudo-critical point, which is hereafter called the minimum drag coefficient phenomenon. However, this special phenomenon was paid a little attention before. Hence systematical experiments have been carried out to investigate the hydraulic resistance of supercritical pressure water in both adiabatic and heated horizontal tubes. Parametric effects of heat flux, pressure and mass fluxes to drag coefficient are further compared. It is found that almost all of the existing correlations don’t agree well with the experimental data due to the insufficient consideration of thermal-properties near the pseudocritical point. Two correlations of the drag coefficients are finally proposed by introducing the new variable of the derivative of density with respect to temperature or Prandtl number, which can better predict the drag coefficient of isothermal and nonisothermal flow respectively.

  3. Experimental techniques to determine salt formation and deposition in supercritical water oxidation reactors

    Energy Technology Data Exchange (ETDEWEB)

    Chan, J.P.C.; LaJeunesse, C.A.; Rice, S.F.

    1994-08-01

    Supercritical Water Oxidation (SCWO) is an emerging technology for destroying aqueous organic waste. Feed material, containing organic waste at concentrations typically less than 10 wt % in water, is pressurized and heated to conditions above water`s critical point where the ability of water to dissolve hydrocarbons and other organic chemicals is greatly enhanced. An oxidizer, is then added to the feed. Given adequate residence time and reaction temperature, the SCWO process rapidly produces innocuous combustion products. Organic carbon and nitrogen in the feed emerge as CO{sub 2} and N{sub 2}; metals, heteroatoms, and halides appear in the effluent as inorganic salts and acids. The oxidation of organic material containing heteroatoms, such as sulfur or phosphorous, forms acid anions. In the presence of metal ions, salts are formed and precipitate out of the supercritical fluid. In a tubular configured reactor, these salts agglomerate, adhere to the reactor wall, and eventually interfere by causing a flow restriction in the reactor leading to an increase in pressure. This rapid precipitation is due to an extreme drop in salt solubility that occurs as the feed stream becomes supercritical. To design a system that can accommodate the formation of these salts, it is important to understand the deposition process quantitatively. A phenomenological model is developed in this paper to predict the time that reactor pressure begins to rise as a function of the fluid axial temperature profile and effective solubility curve. The experimental techniques used to generate effective solubility curves for one salt of interest, Na{sub 2}SO{sub 4}, are described, and data is generated for comparison. Good correlation between the model and experiment is shown. An operational technique is also discussed that allows the deposited salt to be redissolved in a single phase and removed from the affected portion of the reactor. This technique is demonstrated experimentally.

  4. Effect of sub- and supercritical water treatments on the physicochemical properties of crab shell chitin and its enzymatic degradation.

    Science.gov (United States)

    Osada, Mitsumasa; Miura, Chika; Nakagawa, Yuko S; Kaihara, Mikio; Nikaido, Mitsuru; Totani, Kazuhide

    2015-12-10

    This study examined the effects of sub- and supercritical water pretreatments on the physicochemical properties of crab shell α-chitin and its enzymatic degradation to obtain N,N'-diacetylchitobiose (GlcNAc)2. Following sub- and supercritical water pretreatments, the protein in the crab shell was removed and the residue of crab shell contained α-chitin and CaCO3. Prolonged pretreatment led to α-chitin decomposition. The reaction of pure α-chitin in sub- and supercritical water pretreatments was investigated separately; we observed lower mean molecular weight and weaker hydrogen bonds compared with untreated α-chitin. (GlcNAc)2 yields from enzymatic degradation of subcritical (350 °C, 7 min) and supercritical water (400 °C, 2.5 min) pretreated crab shell were 8% and 6%, compared with 0% without any pretreatment. This study shows that sub- and supercritical water pretreatments of crab shell provide to an alternative method to the use of acid and base for decalcification and deproteinization of crab shell required for (GlcNAc)2 production.

  5. Supercritical water oxidation of polyvinyl alcohol and desizing wastewater: influence of NaOH on the organic decomposition.

    Science.gov (United States)

    Zhang, Jie; Wang, Shuzhong; Guo, Yang; Xu, Donghai; Gong, Yanmeng; Tang, Xingying

    2013-08-01

    Polyvinyl alcohol is a refractory compound widely used in industry. Here we report supercritical water oxidation of polyvinyl alcohol solution and desizing wastewater with and without sodium hydroxide addition. However, it is difficult to implement complete degradation of organics even though polyvinyl alcohol can readily crack under supercritical water treatment. Sodium hydroxide had a significant catalytic effect during the supercritical water oxidation of polyvinyl alcohol. It appears that the OH- ion participated in the C-C bond cleavage of polyvinyl alcohol molecules, the CO2-capture reaction and the neutralization of intermediate organic acids, promoting the overall reactions moving in the forward direction. Acetaldehyde was a typical intermediate product during reaction. For supercritical water oxidation of desizing wastewater, a high destruction rate (98.25%) based on total organic carbon was achieved. In addition, cases where initial wastewater was alkaline were favorable for supercritical water oxidation treatment, but salt precipitation and blockage issues arising during the process need to be taken into account seriously.

  6. Supercritical water oxidation of polyvinyl alcohol and desizing wastewater:Influence of NaOH on the organic decomposition

    Institute of Scientific and Technical Information of China (English)

    Jie Zhang; Shuzhong Wang; Yang Guo; Donghai Xu; Yanmeng Gong; Xingying Tang

    2013-01-01

    Polyvinyl alcohol is a refractory compound widely used in industry.Here we report supercritical water oxidation of polyvinyl alcohol solution and desizing wastewater with and without sodium hydroxide addition.However,it is difficult to implement complete degradation of organics even though polyvinyl alcohol can readily crack under supercritical water treatment.Sodium hydroxide had a significant catalytic effect during the supercritical water oxidation of polyvinyl alcohol.It appears that the OH-ion participated in the C-C bond cleavage of polyvinyl alcohol molecules,the CO2-capture reaction and the neutralization of intermediate organic acids,promoting the overall reactions moving in the forward direction.Acetaldehyde was a typical intermediate product during reaction.For supercritical water oxidation of desizing wastewater,a high destruction rate (98.25%) based on total organic carbon was achieved.In addition,cases where initial wastewater was alkaline were favorable for supercritical water oxidation treatment,but salt precipitation and blockage issues arising during the process need to be taken into account seriously.

  7. Oxidation of substituted phenols in supercritical water. Final technical report, September 1992--August 1996

    Energy Technology Data Exchange (ETDEWEB)

    Savage, P.E.

    1996-11-01

    Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or reused. Oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of model pollutants in supercritical water. The decomposition of cresols, hydroxybenzaidehydes, nitrophenols, and benzenediols was studied in dilute aqueous solutions in both the presence and absence of oxygen at 460{degrees}C and 250 atm. Experimental data from the oxidation of these compounds were fit to global, power-law rate expressions. The resulting rate laws showed that the reactivity of the different isomers at 460{degrees}C was in the order of ortho > para > meta for cresols and hydroxybenzaldehydes. Moreover, the CHO-substituted phenol was more reactive than the analogous CH{sub 3}-substituted phenol, and all of these substituted phenols were more reactive than phenol itself. Identifying and quantifying the reaction products of incomplete oxidation allowed us to assemble a general reaction network for the oxidation of cresols in supercritical water. This network comprises parallel primary paths to phenol, to a hydroxybenzaldehyde, and to ring-opening products. The hydroxybenzaldehyde reacts through parallel paths to phenol and to ring-opening products. Phenol also reacts via two parallel paths, but these lead to phenol dimers; and ring-opening products. The dimers are eventually converted to ring-opening products, and the ring-opening products are ultimately converted to CO{sub 2} The relative rates of the different paths in the reaction network are strong functions of the location of the substituent on the phenolic ring.

  8. Reactive extraction of solid fuels using supercritical water-tetralin mixtures. Reaktive Extraktion mit ueberkritischen Wasser-Tetralin-Mischungen

    Energy Technology Data Exchange (ETDEWEB)

    Missal, P.; Canel, M. (Karlsruhe University, Karlsruhe (Germany). Engler-Bunte-Institute)

    1993-06-01

    Earlier investigations at the Engler-Bunte-Institute, Division of Gas, Oil and Coal, Karlsruhe University, showed that supercritical water is a good solvent for the extraction of solid fuels. Now investigations have been carried out with supercritical mixtures of water and tetralin. Using the H-donor tetralin, hydrogen transfer takes place at high temperature and decomposition products produced by thermal cracking of this fuel can be stabilised. The experimental studies have shown that conversion degree and yield of extract increase when water-tetralin mixture are used as solvent. 16 refs., 14 figs.

  9. Diiodination of Alkynes in supercritical Carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    李金恒; 谢叶香; 尹笃林; 江焕峰

    2003-01-01

    A general,green and efficient method for the synthesis of transdiiodoalkenes in CO2(sc) has been developed.Trans-diiodoalkenes were obtained stereospecifically in quantitative yields via diiodination of both electron-rich and electron-deficient alkynes in the presence of KI,Ce(SO4)2 and water in supercritical carbon dioxide [CO2(sc)]at 40℃.

  10. Development of a test facility for analyzing transients in supercritical water-cooled reactors by fractional scaling analysis

    Energy Technology Data Exchange (ETDEWEB)

    Roberto, Thiago D., E-mail: thiagodbtr@gmail.com [Instituto de Engenharia Nuclear (IEN/CNEN—RJ), Rua Hélio de Almeida, 75 21941-972, Rio de Janeiro Caixa-Postal: 68550, RJ (Brazil); Silva, Mário A. B. da, E-mail: mabs500@gmail.com [Departamento de Energia Nuclear (CTG/UFPE), Av. Professor Luiz Freire, 1000, Recife 50740-540, PE (Brazil); Lapa, Celso M.F., E-mail: lapa@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN—RJ), Rua Hélio de Almeida, 75 21941-972, Rio de Janeiro Caixa-Postal: 68550, RJ (Brazil)

    2016-01-15

    The feasibility of performing experiments using water under supercritical conditions is limited by technical and financial difficulties. These difficulties can be overcome by using model fluids that are characterized by feasible supercritical conditions, that is, lower critical pressure and critical temperature. Experimental investigations are normally used to determine the conditions under which model fluids reliably represent supercritical fluids under steady-state conditions. A fluid-to-fluid scaling approach has been proposed to determine the model fluids that represent supercritical fluids in a transient state. Recently, a similar technique known as fractional scaling analysis was developed to establish the conditions under which experiments can be performed using models that represent transients in prototypes. This paper presents a fractional scaling analysis application to determine parameters for a test facility in which transient conditions in supercritical water-cooled reactors are simulated by using carbon dioxide as a model fluid, whose critical point conditions are more feasible than those of water. Similarity is obtained between water (prototype) and carbon dioxide (model) by depressurization in a simple vessel. The main parameters required for the construction of a future test facility are obtained using the proposed method.

  11. Oxidative degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in subcritical and supercritical waters.

    Science.gov (United States)

    Hashimoto, M; Taniguchi, S; Takanami, R; Giri, R R; Ozaki, H

    2010-01-01

    Presence of chlorinated organic compounds in water bodies has become a concern among governments, health authorities and general public. Oxidation of organic compounds in water under high temperature and pressure is considered as a promising technique, but usefulness of the technique to mineralize 2,4-dichlorophenoxyacetic acid (2,4-D) is not well understood. This article aimed to elucidate degradation characteristics of 2,4-D in both subcritical and supercritical waters by laboratory batch experiments. 2,4-D degradation, total organic carbon (TOC) removal and dechlorination increased with increasing reaction time and temperature especially in subcritical waters, while dechlorination was a major step. 2,4-dichlorophenol (2,4-DCP) and acetic acid were the main degradation intermediates both in subcritical and supercritical waters. Though 2,4-D disappeared almost completely in subcritical waters near critical region ( approximately 99%), significant amounts of TOC and organic chlorine still remained as 2,4-DCP and acetic acid. But TOC removal and dechlorination were significantly enhanced ( approximately 95 and 91% respectively) in supercritical waters. Complete mineralization of 2,4-D in subcritical waters required a considerably longer reaction period, while the mineralization was almost complete within a short reaction period in supercritical waters. This is an important information of practical significance for oxidative degradation of chlorinated pesticides similar to 2,4-D.

  12. Feasibility Study of Supercritical Light Water Cooled Fast Reactors for Actinide Burning and Electric Power Production

    Energy Technology Data Exchange (ETDEWEB)

    Mac Donald, Philip Elsworth; Buongiorno, Jacopo; Davis, Cliff Bybee; Weaver, Kevan Dean

    2002-01-01

    The use of supercritical temperature and pressure light water as the coolant in a direct-cycle nuclear reactor offers potential for considerable plant simplification and consequent capital and O&M cost reduction compared with current light water reactor (LWR) designs. Also, given the thermodynamic conditions of the coolant at the core outlet (i.e. temperature and pressure beyond the water critical point), very high thermal efficiencies of the power conversion cycle are possible (i.e. up to 46%). Because no change of phase occurs in the core, the need for steam separators and dryers as well as for BWR-type recirculation pumps is eliminated, which, for a given reactor power, results in a substantially shorter reactor vessel than the current BWRs. Furthermore, in a direct cycle the steam generators are not needed. If a tight fuel rod lattice is adopted, it is possible to significantly reduce the neutron moderation and attain fast neutron energy spectrum conditions. In this project a supercritical water reactor concept with a simple, blanket-free, pancake-shaped core will be developed. This type of core can make use of either fertile or fertile-free fuel and retain the hard spectrum to effectively burn plutonium and minor actinides from LWR spent fuel while efficiently generating electricity.

  13. 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).

  14. The influence of water and supercritical CO2 on the failure behavior of chalk

    Science.gov (United States)

    Liteanu, E.; Spiers, C. J.; de Bresser, J. H. P.

    2013-06-01

    Reduction of compressive strength by injection of water into chalk is a well-known mechanism responsible for increased compaction in chalk reservoirs. This raises the question of whether such effects might be enhanced in the context of long-term storage of CO2 or of CO2 injection for enhanced oil and gas recovery (EOR/EGR) purposes. Therefore, data regarding the effect of supercritical CO2 on the mechanical behavior of chalk are needed. The effect of supercritical CO2 on the short-term failure behavior of wet chalk was accordingly investigated by means of conventional triaxial deformation experiments, performed on Maastrichtian chalk cores under dry conditions, in the presence of saturated chalk solution and using CO2-saturated solution at temperatures simulating reservoir conditions (20-80 °C) and effective confining pressures up to 7 MPa. Increasing temperature from 20 to 80 °C did not show any significant effects on the strength of the dry samples. Addition of aqueous solution to the samples led to drastic weakening of the chalk, the effect being more pronounced at high effective confining pressures (Peff > 3 MPa). Addition of 10 MPa supercritical CO2 to wet samples did not produce any significant additional effect in comparison with the wet samples. All samples showed a yield strength envelope characterized by shear failure at low effective mean stresses giving way to a compaction cap at high mean stresses. The weakening effect of aqueous solution was explained in terms of a reduction in frictional resistance of the material, due to water-enhanced grain-contact cracking, and perhaps pressure solution, with a possible contribution by disjoining pressure effects caused by water adsorption. While CO2 does not seem to reduce short-term failure strength of wet chalk, processes such as intergranular pressure solution have to be considered for assessing mechanical stability of chalk in the context of long-term CO2 storage or EOR/EGR operations.

  15. Water-cooled electronics

    CERN Document Server

    Dumont, G; Righini, B

    2000-01-01

    LHC experiments demand on cooling of electronic instrumentation will be extremely high. A large number of racks will be located in underground caverns and counting rooms, where cooling by conventional climatisation would be prohibitively expensive. A series of tests on the direct water cooling of VMEbus units and of their standard power supplies is reported. A maximum dissipation of 60 W for each module and more than 1000 W delivered by the power supply to the crate have been reached. These values comply with the VMEbus specifications. (3 refs).

  16. Corrosion behavior of oxide dispersion strengthened ferritic steels in supercritical water

    Science.gov (United States)

    Gao, Wenhua; Guo, Xianglong; Shen, Zhao; Zhang, Lefu

    2017-04-01

    The corrosion resistance of three different Cr content oxide dispersion strengthened (ODS) ferritic steels in supercritical water (SCW) and their passive films formed on the surface have been investigated. The results show that the dissolved oxygen (DO) and chemical composition have significant influence on the corrosion behavior of the ODS ferritic steels. In 2000 ppb DO SCW at 650 °C, the 14Cr-4Al ODS steel forms a tri-layer oxide film and the surface morphologies have experienced four structures. For the tri-layer oxide film, the middle layer is mainly Fe-Cr spinel and the Al is gradually enriched in the inner layer.

  17. Supercritical water oxidation for the destruction of toxic organic wastewaters: A review

    Institute of Scientific and Technical Information of China (English)

    VERIANSYAH Bambang; KIM Jae-Duck

    2007-01-01

    The destruction of toxic organic wastewaters from munitions demilitarization and complex industrial chemical clearly becomes an overwhelming problem if left to conventional treatment processes. Two options, incineration and supercritical water oxidation (SCWO), exist for the complete destruction of toxic organic wastewaters. Incinerator has associated problems such as very high cost and public resentment; on the other hand, SCWO has proved to be a very promising method for the treatment of many different wastewaters with extremely efficient organic waste destruction 99.99% with none of the emissions associated with incineration. In this review, the concepts of SCWO, result and present perspectives of application, and industrial status of SCWO are critically examined and discussed.

  18. Final report on the oxidation of energetic materials in supercritical water. Final Air Force report

    Energy Technology Data Exchange (ETDEWEB)

    Buelow, S.J.; Allen, D.; Anderson, G.K. [and others

    1995-04-03

    The objective of this project was to determine the suitability of oxidation in supercritical fluids (SCO), particularly water (SCWO), for disposal of propellants, explosives, and pyrotechnics (PEPs). The SCO studies of PEPs addressed the following issues: The efficiency of destruction of the substrate. The products of destruction contained in the effluents. Whether the process can be conducted safely on a large scale. Whether energy recovery from the process is economically practicable. The information essential for process development and equipment design was also investigated, including issues such as practical throughput of explosives through a SCWO reactor, reactor materials and corrosion, and models for process design and optimization.

  19. Advanced Computational Thermal Fluid Physics (CTFP) and Its Assessment for Light Water Reactors and Supercritical Reactors

    Energy Technology Data Exchange (ETDEWEB)

    D.M. McEligot; K. G. Condie; G. E. McCreery; H. M. McIlroy; R. J. Pink; L.E. Hochreiter; J.D. Jackson; R.H. Pletcher; B.L. Smith; P. Vukoslavcevic; J.M. Wallace; J.Y. Yoo; J.S. Lee; S.T. Ro; S.O. Park

    2005-10-01

    Background: The ultimate goal of the study is the improvement of predictive methods for safety analyses and design of Generation IV reactor systems such as supercritical water reactors (SCWR) for higher efficiency, improved performance and operation, design simplification, enhanced safety and reduced waste and cost. The objective of this Korean / US / laboratory / university collaboration of coupled fundamental computational and experimental studies is to develop the supporting knowledge needed for improved predictive techniques for use in the technology development of Generation IV reactor concepts and their passive safety systems. The present study emphasizes SCWR concepts in the Generation IV program.

  20. Obtaining of gas, liquid, and upgraded solid fuel from brown coals in supercritical water

    Science.gov (United States)

    Vostrikov, A. A.; Fedyaeva, O. N.; Dubov, D. Yu.; Shishkin, A. V.; Sokol, M. Ya.

    2013-12-01

    Two new conversion methods of brown coals in water steam and supercritical water (SCW) are proposed and investigated. In the first method, water steam or SCW is supplied periodically into the array of coal particles and then is ejected from the reactor along with dissolved conversion products. The second method includes the continuous supply of water-coal suspension (WCS) into the vertically arranged reactor from above. When using the proposed methods, agglomeration of coal particles is excluded and a high degree of conversion of coal into liquid and gaseous products is provided. Due to the removal of the main mass of oxygen during conversion in the composition of CO2, the high heating value of fuels obtained from liquid substantially exceeds this characteristic of starting coal. More than half of the sulfur atoms transfer into H2S during the SCW conversion already at a temperature lower than 450°C.

  1. Failure Analysis of 600 MW Supercritical Boiler Water Wall

    OpenAIRE

    Fu Huilin; Cai Zhengchun; Yan Xiaozhong; He Jinqiao; Zhou Yucai

    2013-01-01

    Boiler tube often causes abnormal boiler outage, bringing greater economic losses. This thesis mainly comes from the dynamics of boiler water, boiler furnace accident location of wall temperature distribution to explore the cause of the accident boiler. Calculation results show that the deformation will seriously reduce the boiler allowable maximum temperature difference between the screens. And the boiler is not over-temperature, low temperature difference between the screens, which have bur...

  2. Direct energy recovery from primary and secondary sludges by supercritical water oxidation.

    Science.gov (United States)

    Svanström, M; Modell, M; Tester, J

    2004-01-01

    Supercritical water oxidation (SCWO) oxidizes organic and biological materials virtually completely to benign products without the need for stack gas scrubbing. Heavy metals are recovered as stabilized solid, along with the sand and clay that is present in the feed. The technology has been under development for twenty years. The major obstacle to commercialization has been developing reactors that are not clogged by inorganic solid deposits. That problem has been solved by using tubular reactors with fluid velocities that are high enough to keep solids in suspension. Recently, system designs have been created that reduce the cost of processing sewage sludges below that of incineration. At 10 wt- % dry solids, sludge can be oxidized with virtually complete recovery of the sludge heating value as hot water or high-pressure steam. Liquid carbon dioxide of high purity can be recovered from the gaseous effluent and excess oxygen can be recovered for recycle. The net effect is to reduce the stack to a harmless vent with minimal flow rate of a clean gas. Complete simulations have been developed using physical property models that accurately simulate the thermodynamic properties of sub- and supercritical water in mixtures with O2, N2, CO2, and organics. Capital and operating cost estimates are given for sewage sludge treatment, which are less costly than incineration. The scenario of direct recovery of energy from sludges has inherent benefits compared to other gasification or liquefaction options.

  3. Partial oxidation of n-hexadecane through decomposition of hydrogen peroxide in supercritical water

    KAUST Repository

    Alshammari, Y.M.

    2015-01-01

    © 2014 The Institution of Chemical Engineers. This work reports the experimental analysis of partial oxidation of n-hexadecane under supercritical water conditions. A novel reactor flow system was developed which allows for total decomposition of hydrogen peroxide in a separate reactor followed partial oxidation of n-hexadecane in a gasification reactor instead of having both reactions in one reactor. The kinetics of hydrothermal decomposition of hydrogen peroxide was studied in order to confirm its full conversion into water and oxygen under the desired partial oxidation conditions, and the kinetic data were found in a good agreement with previously reported literature. The gas yield and gasification efficiency were investigated under different operating parameters. Furthermore, the profile of C-C/C=C ratio was studied which showed the favourable conditions for maximising yields of n-alkanes via hydrogenation of their corresponding 1-alkenes. Enhanced hydrogenation of 1-alkenes was observed at higher O/C ratios and higher residence times, shown by the increase in the C-C/C=C ratio to more than unity, while increasing the temperature has shown much less effect on the C-C/C=C ratio at the current experimental conditions. In addition, GC-MS analysis of liquid samples revealed the formation of heavy oxygenated compounds which may suggest a new addition reaction to account for their formation under the current experimental conditions. Results show new promising routes for hydrogen production with in situ hydrogenation of heavy hydrocarbons in a supercritical water reactor.

  4. Direct Energy Recovery from Primary and Secondary Sludges by Supercritical Water Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Svanstroem, Magdalena; Modell, Michael; Tester, Jefferson

    2003-07-01

    Supercritical water oxidation (SCWO) oxidizes organic and biological materials virtually completely to benign products without the need for stack gas scrubbing. Heavy metals are recovered as stabilized solid, along with the sand and clay that is present in the feed. The technology has been under development for twenty years. The major obstacle to commercialization has been developing reactors that are not clogged by inorganic solid deposits. That problem has been solved by using tubular reactors with fluid velocities that are high enough to keep solids in suspension. Recently, system designs have been created that reduce the cost of processing sewage sludges below that of incineration. At 10 wt-% dry solids, sludge can be oxidized with virtually complete recovery of the sludge heating value as hot water or high-pressure steam. Liquid carbon dioxide of high purity can be recovered from the gaseous effluent and excess oxygen can be recovered for recycle. The net effect is to reduce the stack to a harmless vent with minimal flow rate of a clean gas. Complete simulations have been developed using physical property models that accurately simulate the thermodynamic properties of sub- and supercritical water in mixtures with O{sub 2}, N{sub 2}, CO{sub 2}. and organics. Capital and operating cost estimates are given for sewage sludge treatment, which are less costly than incineration. The scenario of direct recovery of energy from sludges has inherent benefits compared to other gasification or liquefaction options. (author)

  5. Coating properties of a novel water stationary phase in capillary supercritical fluid chromatography.

    Science.gov (United States)

    Murakami, Jillian N; Thurbide, Kevin B

    2015-05-01

    The coating properties of a novel water stationary phase used in capillary supercritical fluid chromatography were investigated. The findings confirm that increasing the length or internal diameter of the type 316 stainless-steel column used provides a linear increase in the volume of stationary phase present. Under normal operating conditions, results indicate that about 4.9 ± 0.5 μL/m of water phase is deposited uniformly inside of a typical 250 μm internal diameter 316 stainless-steel column, which translates to an area coverage of about 6.3 ± 0.5 nL/mm(2) regardless of dimension. Efforts to increase the stationary phase volume present showed that etching the stainless-steel capillary wall using hydrofluoric acid was very effective for this. For instance, after five etching cycles, this volume doubled inside of both the type 304 and the type 316 stainless-steel columns examined. This in turn doubled analyte retention, while maintaining good peak shape and column efficiency. Overall, 316 stainless-steel columns were more resistant to etching than 304 stainless-steel columns. Results indicate that this approach could be useful to employ as a means of controlling the volume of water stationary phase that can be established inside of the stainless-steel columns used with this supercritical fluid chromatography technique.

  6. Investigation on adsorption and regeneration performances of multi-walled carbon nanotubes by supercritical water technique

    Institute of Scientific and Technical Information of China (English)

    HE Jin-mei; HUANG Yu-dong; MENG Ling-hui; ZHAO Jin-hua; SUN De-zhi

    2009-01-01

    In this paper,adsorption and regeneration characteristics of multi-walled carbon nanotubes (MWNTs)used as adsorbent were investigated for the removal of l,3-benzenediol(BDO)from water by the supercritical water(SCW)technique.FTIR,XPS,SEM and dispersion stability tests were used to characterize the structure and surface morphology of CNTs.The results showed that CNTs surfaces were slishfly activated and strongly etched in supercritical water system.The adsorption capacity of SCW-treated CNTs was hisher than that of raw CNTs.The adsorbed amounts for treated CNTs and raw CNTs samples at the same initial concentra-tion of 60 mg/L were ca.16.42 and 7.30 mg/g,respectively.The BDO adsorption of treated CNTs Was due to the physical adsorption.The experimental data fit Freundlich isotherm model better than Langmuir one.The loaded adsorbent could be efficiently desorbed and regenerated by SCW technique.Therefore,SCW is a promis-ing and environmentally friendly technique for the improvement of adsorption and regeneration of CNTs.

  7. Supercritical water oxidation of Quinazoline: Effects of conversion parameters and reaction mechanism.

    Science.gov (United States)

    Gong, Yanmeng; Guo, Yang; Wang, Shuzhong; Song, Wenhan

    2016-09-01

    The supercritical water oxidation reaction of quinazoline and a set of related reaction products were investigated in batch reactors by varying the temperature (T, 400-600 °C), time (t, 0-400 s), water density (ρ, 70.79-166.28  kg m(-3)) and oxidation coefficient (OC, 0-4.0). The TOC removal efficiency (CRE) increased significantly as the OC increased, whereas this effect was very limited at high OC (>2.0). Lack of oxygen resulted in low CRE and TN removal efficiency (NRE), also cause coke-formation, and giving high yield of NH3 and nitrogenous organic intermediates. Prolonging reaction time did not provide an appreciable improvement on CRE but remarkably increased NRE at temperature higher than 500 °C. Pyrimidines and pyridines as the nitrogenous intermediates were largely found in GC-MS spectrum. Polymerization among benzene, phenyl radical and benzyl radical played important roles in the formation of PAHs, such as naphthalene, biphenyl, phenanthrene. These collective results showed how the yield of intermediate products responded to changes in the process variables, which permitted the development of a potential reaction network for supercritical water oxidation of quinazoline.

  8. New Class of Amphiphiles Designed for Use in Water-in-Supercritical CO2 Microemulsions.

    Science.gov (United States)

    Sagisaka, Masanobu; Ogiwara, Shunsuke; Ono, Shinji; James, Craig; Yoshizawa, Atsushi; Mohamed, Azmi; Rogers, Sarah E; Heenan, Richard K; Yan, Ci; Peach, Jocelyn Alice; Eastoe, Julian

    2016-11-29

    Water-in-supercritical CO2 microemulsions formed using the hybrid F-H surfactant sodium 1-oxo-1-[4-(perfluorohexyl)phenyl]hexane-2-sulfonate, FC6-HC4, have recently been shown to have the highest water-solubilizing power ever reported. FC6-HC4 demonstrated the ability to outperform not only other surfactants but also other FCm-HCn analogues containing different fluorocarbon and hydrocarbon chain lengths (Sagisaka, M. et al. Langmuir 2015, 31, 7479-7487). With the aim of clarifying the key structural features of this surfactant, this study examined the phase behavior and water/supercritical CO2 aggregate formation of 1-oxo-1-[4-(perfluorohexyl)phenyl]hexane (Nohead FC6-HC4), which is an FC6-HC4 analogue but now, interestingly, without the sulfonate headgroup. Surprisingly, Nohead FC6-HC4, which would not normally be identified as a classic surfactant, yielded transparent single-phase W/CO2 microemulsions with polar cores able to solubilize a water-soluble dye, even at pressures and temperatures so low as to approach the critical point of CO2 (e.g., ∼100 bar at 35 °C). High-pressure small-angle scattering (SANS) measurements revealed the transparent phases to consist of ellipsoidal nanodroplets of water. The morphology of these droplets was shown to be dependent on the pressure, Nohead FC6-HC4 concentration, and water-to-surfactant molar ratio. Despite having almost the same structure as Nohead FC6-HC4, analogues containing both shorter and longer hydrocarbons were unable to form W/CO2 microemulsion droplets. This shows the importance of the role of the hydrocarbon chain in the stabilization of W/CO2 microemulsions. A detailed examination of the mechanism of Nohead FC6-HC4 adsorption onto the water surface suggests that the hexanoyl group protrudes into the aqueous core, allowing for association between the carbonyl group and water.

  9. Kinetics of Hydrothermal Reactions of Minerals in Near-critical and Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This work presents new experimental results on the kinetics of mineral dissolution in near-critical and supercritical water in a temperature range (T) from 25 to 400° C and a constant pressure of 23 MPa. Kinetic experiments were carried out by using a flow reactor (packed bed reactor) of an open system. The dissolution rates of albite and magnetite were measured under these experimental conditions. Na, Al and Si release rates for albite dissolution in water were measured as a function of the temperature and flow velocity in the reaction system. The maximum release rates of Na, Al and Si of albite dissolution in the hydrothermal flow systems under different flow velocities were always obtained at 300° C, that is to say, the maximum albite dissolution rates in the flow systems, regardless of different flow rates, were repeatedly measured at 300° C. Results indicate a wide fluctuation in albite dissolution rates occurring close to the critical point of water. The dissolution rates increased when the temperatures increased from 25 to 300° C and decreased when the temperatures increase from 300 to 400° C. At some flow velocities, the dissolution rates rose as the temperature surpassed 374° C. Albite dissolution was incongruent in water at most temperatures. It was only at 300° C that albite dissolution was congruent. The albite dissolution from 25 to 300° C (at 23 MPa) will change from incongruent to congruent, whereas from subcritical 300 to 400° C (at 23 MPa), the dissolution will change from congruent to incongruent. The release ratio of Al/Si (or Na/Si) is positive at T300° C. The dissolution rates of magnetite in water increased with increasing T until T at the critical point of water or around it. The authors believe that this is caused by the wide fluctuations in water properties under the conditions from the near-critical to supercritical state.

  10. Experimental study of critical flow of water at supercritical pressure

    Institute of Scientific and Technical Information of China (English)

    Yuzhou CHEN; Chunsheng YANG; Shuming ZHANG; Minfu ZHAO; Kaiwen DU; Xu CHENG

    2009-01-01

    Experimental studies of the critical flow of water were conducted under steady-state conditions with a nozzle 1.41mm in diameter and 4.35 mm in length, covering the inlet pressure range of 22.1-26.8 MPa and inlet temperature range of 38^74°C. The parametric trend of the flow rate was investigated, and the experimental data were compared with the predictions of the homogeneous equilibrium model, the Bernoulli correlation, and the models used in the reactor safety analysis code RELAP5/ MOD3.3. It is concluded that in the near or beyond pseudo-critical region, thermal-dynamic equilibrium is dominant, and at a lower temperature, choking does not occur. The onset of the choking condition is not predicted reasonably by the RELAP5 code.

  11. Effects of water on reactions for waste treatment, organic synthesis, and bio-refinery in sub- and supercritical water.

    Science.gov (United States)

    Akizuki, Makoto; Fujii, Tatsuya; Hayashi, Rumiko; Oshima, Yoshito

    2014-01-01

    Current research analyzing the effects of water in the field of homogeneous and heterogeneous reactions of organics in sub- and supercritical water are reviewed in this article. Since the physical properties of water (e.g., density, ion product and dielectric constants) can affect the reaction rates and mechanisms of various reactions, understanding the effects that water can have is important in controlling reactions. For homogeneous reactions, the effects of water on oxidation, hydrolysis, aldol condensation, Beckman rearrangement and biomass refining were introduced including recent experimental results up to 100 MPa using special pressure-resistance equipment. For heterogeneous reactions, the effects of ion product on acid/base-catalyzed reactions, such as hydrothermal conversion of biomass-related compounds, organic synthesis in the context of bio-refinery, and hydration of olefins were described and how the reaction paths are controlled by the concentration of water and hydrogen ions was summarized.

  12. Hydrothermal liquefaction of Spirulina and Nannochloropsis Salina under subcritical and supercritical water conditions

    DEFF Research Database (Denmark)

    Toor, Saqib; Reddy, H.; Deng, S.

    2013-01-01

    Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220-375 °C, 20-255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid...... residue, and recycling process water for algae cultivation. GC-MS, elemental analyzer, FT-IR, calorimeter and nutrient analysis were used to analyze bio-crude, lipid-extracted algae and water samples produced in the hydrothermal liquefaction process. The highest bio-crude yield of 46% was obtained...... on Nannochloropsis salina at 350 °C and 175 bar. For Spirulina platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for Nannochloropsis salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae...

  13. Continuous catalyst-free methanolysis and ethanolysis of soybean oil under supercritical alcohol/water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Vieitez, Ignacio; Grompone, Maria A.; Jachmanian, Ivan [Laboratorio de Grasas y Aceites, Departamento de Alimentos, Facultad de Quimica, Universidad de la Republica, Montevideo 11800 (Uruguay); da Silva, Camila; Alckmin, Isabella; Borges, Gustavo R.; Corazza, Fernanda C.; Oliveira, J. Vladimir [Department of Food Engineering, URI-Campus de Erechim, Erechim 99700-000 (Brazil)

    2010-09-15

    This work investigates and compares the reaction performance of soybean oil transesterification under supercritical methanol and ethanol, in a continuous catalyst-free process, as a cleaner alternative to conventional chemically catalyzed process. Reactions were performed in a tubular reactor, at 20 MPa, with oil to alcohol ratio of 1:40, varying the temperature in the range from 250 C to 350 C, and at two levels of water concentrations, 0 and 10 wt%. Although both processes proceeded with a relatively high reaction rate, conversion achieved by methanolysis was higher than that obtained by ethanolysis. Water positively affected both process: higher ester content and triacylglycerols depletion occurred when 10 wt% water was used compared with anhydrous conditions. Temperature increase favored the conversion of soybean oil to the corresponding methyl or ethyl esters, although temperatures above 300 C increased the fatty acid degradation degree, a phenomenon responsible for the low ester contents obtained at the highest temperatures and lowest flow rates studied. (author)

  14. Fundamental Understanding of Crack Growth in Structural Components of Generation IV Supercritical Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Iouri I. Balachov; Takao Kobayashi; Francis Tanzella; Indira Jayaweera; Palitha Jayaweera; Petri Kinnunen; Martin Bojinov; Timo Saario

    2004-11-17

    This work contributes to the design of safe and economical Generation-IV Super-Critical Water Reactors (SCWRs) by providing a basis for selecting structural materials to ensure the functionality of in-vessel components during the entire service life. During the second year of the project, we completed electrochemical characterization of the oxide film properties and investigation of crack initiation and propagation for candidate structural materials steels under supercritical conditions. We ranked candidate alloys against their susceptibility to environmentally assisted degradation based on the in situ data measure with an SRI-designed controlled distance electrochemistry (CDE) arrangement. A correlation between measurable oxide film properties and susceptibility of austenitic steels to environmentally assisted degradation was observed experimentally. One of the major practical results of the present work is the experimentally proven ability of the economical CDE technique to supply in situ data for ranking candidate structural materials for Generation-IV SCRs. A potential use of the CDE arrangement developed ar SRI for building in situ sensors monitoring water chemistry in the heat transport circuit of Generation-IV SCWRs was evaluated and proved to be feasible.

  15. Supercritical water oxidation of tannery sludge: stabilization of chromium and destruction of organics.

    Science.gov (United States)

    Zou, Daoan; Chi, Yong; Dong, Jun; Fu, Chao; Wang, Fei; Ni, Mingjiang

    2013-10-01

    The supercritical water oxidation (SCWO) of industrial tannery sludge was investigated to understand the simultaneous destruction of organic pollutants and recovery of high content chromium. Experiments were performed in a batch reactor at temperatures of 350-500 °C, reaction time of 150-300 s and different oxygen ratios, to exhibit the effect of operation conditions. Results showed that removal efficiency of chemical oxygen demand (COD) increased with higher temperature, larger oxidant amount and reaction time; a maximum value of 96% was obtained. Meanwhile, destruction yield was much higher under supercritical conditions than that in subcritical water. In addition, removal efficiency of Cr from sludge reached more than 98% under all conditions; higher temperature played a positive role. Further, leaching toxicity tests of heavy metals in solid products were conducted based on toxicity characteristic leaching procedure. All heavy metals except nickel showed a greatly reduced leaching toxicity through their stabilization. The chromium oxide recovered in ash was amorphous below 550 °C, so that the structure of Cr could not be identified by X-ray diffraction pattern. Special attention should be paid on nickel as its leaching toxicity increased due to the corrosion of reactor surface under severe reaction conditions.

  16. Catalytic dehydration of biomass-derived polyols in sub- and supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Lehr, Vanessa; Sarlea, Michael; Ott, Lothar; Vogel, H. [Darmstadt University of Technology, Ernst-Berl-Institute of Technical Chemistry and Macromolecular Science, Petersenstrasse 20, D-64287 Darmstadt (Germany)

    2007-03-15

    The increasing CO{sub 2} content in the atmosphere and the increasing demand for raw materials due to population growth makes the organisation of a post-fossil and sustainable era of energy and material supply, and the development of new chemical processes for intermediates essential. One possibility is to use biomass as a renewable material source. This is the reason why several polyols ({yields}1,2- and 1,3-propanediol; 1,2-butanediol; glycerol and m-erythritol), which are easily available from sugars via biochemical conversion or hydrogenolytic cleavage, were dehydrated in sub- and supercritical water (SCW). During the dehydration of polyols in SCW mainly aldehydes or furan derivatives are formed, which are important industrial intermediates. The focus was on the influence of electrolytes versus acids on the reactions. It could be concluded that converting polyols in sub- and supercritical water with the addition of bivalent transition metal sulphates is a well-promising approach to substitute crude oil based processes for the CO{sub 2}-neutral production of intermediates from renewable resources. (author)

  17. Decomposition kinetics of dimethyl methylphospate(chemical agent simulant) by supercritical water oxidation

    Institute of Scientific and Technical Information of China (English)

    Bambang VERIANSYAH; Jae-Duck KIM; Youn-Woo LEE

    2006-01-01

    Supercritical water oxidation (SCWO) has been drawing much attention due to effectively destroy a large variety of high-risk wastes resulting from munitions demilitarization and complex industrial chemical. An important design consideration in the development of supercritical water oxidation is the information of decomposition rate. In this paper, the decomposition rate of dimethyl methylphosphonate(DMMP), which is similar to the nerve agent VX and GB(Sarin) in its structure, was investigated under SCWO conditions. The experiments were performed in an isothermal tubular reactor with a H2O2 as an oxidant. The reaction temperatures were ranged from 398 to 633 ℃ at a fixed pressure of 24 MPa. The conversion of DMMP was monitored by analyzing total organic carbon (TOC) on the liquid effluent samples. It is found that the oxidative decomposition of DMMP proceeded rapidly and a high TOC decomposition up to 99.99% was obtained within 11 s at 555℃. On the basis of data derived from experiments, a global kinetic equation for the decomposition of DMMP was developed. The model predictions agreed well with the experimental data.

  18. Hydrogen generation from polyvinyl alcohol-contaminated wastewater by a process of supercritical water gasification

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Gasification of polyvinyl alcohol (PVA)-contaminated wastewater in supercritical water (SCW) was investigated in a continuous flow reactor at 723-873 K, 20-36 MPa and residence time of 20-60 s. The gas and liquid products were analyzed by GC/TCD, TOC analyzer and GC/MS. The main gas products were H2, CH4, CO and CO2. Pressure change had no significant influence on gasification efficiency. Higher temperature and longer residence time enhanced gasification efficiency, and lower temperature favored the production of H2. The effects of KOH catalyst on gas product composition were studied, and gasification efficiency were analyzed. The TOC removal efficiency (TOCR), carbon gasification ratio (CGR) and hydrogen gasification ratio (HGR) were up to 96.00%, 95.92% and 126.40% at 873 K and 60 s, respectively, which suggests PVA can be completely gasified in SCW. The results indicate supercritical water gasification for hydrogen generation is a promising process for the treatment of PVA wastewater.

  19. Degradation mechanism of 2,4,6-trinitrotoluene in supercritical water oxidation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The 2,4,6-trinitrotoluene (TNT) is a potential carcinogens and TNT contaminated wastewater, which could not be effectively disposed with conventional treatments. The supercritical water oxidation (SCWO) to treat TNT contaminated wastewater was studied in this article. The TNT concentration in wastewater was measured by high-performance liquid chromatograph (HPLC) and the degraded intermediates were analyzed using GC-MS. The results showed that SCWO could degrade TNT efficiently with O2. The reaction temperature, pressure, residence time and oxygen excess were the main contributing factors in the process. The decomposition of TNT was accelerated as the temperature or residence time increases. At 550℃, 24 MPa, 120 s and oxygen excess 300%, TNT removal rate could exceed 99.9%. Partial oxidation occurs in SCWO without oxygen. It was concluded that supercritical water was a good solvent and had excellent oxidation capability in the existence of oxygen. The main intermediates of TNT during SCWO include toluene, 1,3,5-trinitrobenzene, nitrophenol, naphthalene, fluorenone, dibutyl phthalate, alkanes and several dimers based on the intermediate analysis. Some side reactions, such as coupled reaction, hydrolysis reaction and isomerization reaction may take place simultaneously as TNT is oxidized by SCWO.

  20. Energetic analysis of gasification of biomass by partial oxidation in supercritical water

    Institute of Scientific and Technical Information of China (English)

    Qingqing Guan; Chaohai Wei; Xinsheng Chai; Ping Ning; Senlin Tian; Junjie Gu; Qiuling Chen; Rongrong Miao

    2015-01-01

    Partial oxidation gasification in supercritical water could produce fuel gases (such as H2, CO and CH4) and signif-icantly reduce the energy consumption. In this work, an energetic model was developed to analyze the partial oxidative gasification of biomass (glucose and lignin) in supercritical water and the related key factors on which gasification under autothermal condition depended upon. The results indicated that the oxidant equiva-lent ratio (ER) should be over 0.3 as the concern about energy balance but less than 0.6 as the concern about fuel gas production. Feedstocks such as glucose and lignin also had different energy recovery efficiency. For ma-terials which can be efficiently gasified, the partial oxidation might be a way for energy based on the combustion of fuel gases. Aromatic materials such as lignin and coal are more potential since partial oxidation could produce similar amount of fuel gases as direct gasification and offer additional energy. Energy recovered pays a key role to achieve an autothermal process. Keeping heat exchanger efficiency above 80%and heat transfer coefficient below 15 kJ·s−1 is necessary to maintain the autothermal status. The results also indicated that the biomass loading should be above 15%but under 20%for an autothermal gasification, since the increase of biomass loading could improve the energy supplied but decrease the efficiency of gasification and gaseous yields. In general, some specific conditions exist among different materials.

  1. Supercritical Water Reactor (SCWR) - Survey of Materials Research and Development Needs to Assess Viability

    Energy Technology Data Exchange (ETDEWEB)

    Philip E. MacDonald

    2003-09-01

    Supercritical water-cooled reactors (SCWRs) are among the most promising advanced nuclear systems because of their high thermal efficiency [i.e., about 45% vs. 33% of current light water reactors (LWRs)] and considerable plant simplification. SCWRs achieve this with superior thermodynamic conditions (i.e., high operating pressure and temperature), and by reducing the containment volume and eliminating the need for recirculation and jet pumps, pressurizer, steam generators, steam separators and dryers. The reference SCWR design in the U.S. is a direct cycle, thermal spectrum, light-water-cooled and moderated reactor with an operating pressure of 25 MPa and inlet/outlet coolant temperature of 280/500 °C. The inlet flow splits, partly to a down-comer and partly to a plenum at the top of the reactor pressure vessel to flow downward through the core in special water rods to the inlet plenum. This strategy is employed to provide good moderation at the top of the core, where the coolant density is only about 15-20% that of liquid water. The SCWR uses a power conversion cycle similar to that used in supercritical fossil-fired plants: high- intermediate- and low-pressure turbines are employed with one moisture-separator re-heater and up to eight feedwater heaters. The reference power is 3575 MWt, the net electric power is 1600 MWe and the thermal efficiency is 44.8%. The fuel is low-enriched uranium oxide fuel and the plant is designed primarily for base load operation. The purpose of this report is to survey existing materials for fossil, fission and fusion applications and identify the materials research and development needed to establish the SCWR viabilitya with regard to possible materials of construction. The two most significant materials related factors in going from the current LWR designs to the SCWR are the increase in outlet coolant temperature from 300 to 500 °C and the possible compatibility issues associated with the supercritical water environment.

  2. Insights into Silicate Carbonation Processes in Water-Bearing Supercritical CO2 Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Quin RS; Thompson, Christopher J.; Loring, John S.; Windisch, Charles F.; Bowden, Mark E.; Hoyt, David W.; Hu, Jian Z.; Arey, Bruce W.; Rosso, Kevin M.; Schaef, Herbert T.

    2013-07-01

    Long-term geologic storage of carbon dioxide (CO2) is considered an integral part to moderating CO2 concentrations in the atmosphere and subsequently minimizing effects of global climate change. Although subsurface injection of CO2 is common place in certain industries, deployment at the scale required for emission reduction is unprecedented and therefore requires a high degree of predictability. Accurately modeling geochemical processes in the subsurface requires experimental derived data for mineral reactions occurring between the CO2, water, and rocks. Most work in this area has focused on aqueous-dominated systems in which dissolved CO2 reacts to form crystalline carbonate minerals. Comparatively little laboratory research has been conducted on reactions occurring between minerals in the host rock and the wet supercritical fluid phase. In this work, we studied the carbonation of wollastonite [CaSiO3] exposed to variably hydrated supercritical CO2 (scCO2) at a range of temperatures (50, 55 and 70 °C) and pressures (90,120 and 160 bar) that simulate conditions in geologic repositories. Mineral transformation reactions were followed by three novel in situ high pressure techniques, including x-ray diffraction that tracked the rate and extents of wollastonite conversion to calcite. Increased dissolved water concentrations in the supercritical CO2 resulted in increased silicate carbonation approaching ~50 wt. %. Development of thin water films on the mineral surface were directly observed with infrared spectroscopy and determined to be critical for facilitating carbonation processes. Even in extreme low water conditions, magic angle spinning nuclear magnetic resonance detected formation of Q3 [Si(OSi)3OH] and Q4 [Si(OSi)4] amorphous silica species. Unlike the thick (<10 μm) passivating silica layers observed in the fully water saturated scCO2 experiments, images obtained from a focused ion beam sectioned sample indicted these coatings were chemically wollastonite

  3. Stability of Chromium Carbide/Chromium Oxide Based Porous Ceramics in Supercritical Water

    Science.gov (United States)

    Dong, Ziqiang

    This research was aimed at developing porous ceramics as well as ceramic-metal composites that can be potentially used in Gen-IV supercritical water reactors (SCWR). The research mainly includes two parts: 1) fabricating and engineering the porous ceramics and porous ceramic-metal composite; 2) Evaluating the stability of the porous ceramics in SCW environments. Reactive sintering in carbonaceous environments was used to fabricate porous Cr3C2/Cr2O3-based ceramic. A new process consisting of freeze casting and reactive sintering has also been successfully developed to fabricate highly porous Cr3C 2 ceramics with multiple interconnected pores. Various amounts of cobalt powders were mixed with ceramic oxides in order to modify the porous structure and property of the porous carbide obtained by reactive sintering. The hardness of the M(Cr,Co)7C3-Co composite has been evaluated and rationalized based on the solid solution of cobalt in the ceramic phase, the composite effect of soft Co metal and the porous structure of the ceramic materials. Efforts have also been made in fabricating and evaluating interpenetrating Cr3C2-Cu composites formed by infiltrating liquid copper into porous Cr3C2. The corrosion evaluation mainly focused on assessing the stability of porous Cr3C2 and Cr2O3 under various SCW conditions. The corrosion tests showed that the porous Cr3C 2 is stable in SCW at temperatures below 425°C. However, cracking and disintegrating of the porous Cr3C2 occurred when the SCW temperature increased above 425°C. Mechanisms of the corrosion attack were also investigated. The porous Cr2O3 obtained by oxidizing the porous Cr3C2 was exposed to various SCW environments. It was found that the stability of Cr 2O 3 was dependent on its morphology and the SCW testing conditions. Increasing SCW temperature increased the dissociation rate of the Cr2O 3. Adding proper amount of Y2O3 can increase the stability of the porous Cr2O3 in SCW. It was also concluded that decreasing

  4. Supercritical water gasification of microalga Nannochloropsis over supported Ni and Ru catalysts

    Science.gov (United States)

    Wijenayake, A. G. B. S. P.; Hassan, M.; Komiyama, M.

    2016-11-01

    Supercritical water gasification (SCWG) of a marine microalga Nannochloropsis was performed in the presence and the absence of supported Ru and Ni catalysts at 385 °C and 26 MPa using a batch reactor. The product gas of the non-catalytic reaction mainly comprised of CO2 while that of catalytic reaction produced CH4, CO2, H2 and some C2-C4 compounds. The addition of catalysts enhanced the decomposition and conversion (water-gas shift and methanation) reactions, consequently increasing the total gasification efficiency up to 92% for 60 min reaction time. Between the supported Ru and Ni catalysts, Ru resulted in higher gasification efficiency than Ni. Catalyst deactivation during SCWG of Nannochloropsis was also examined.

  5. Analysis of product distribution and characteristics in hydrothermal liquefaction of barley straw in subcritical and supercritical water

    DEFF Research Database (Denmark)

    Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse

    2014-01-01

    In this study, hydrothermal liquefaction of barley straw in subcritical and supercritical water with potassium carbonate catalyst was performed in the temperatures range of 280-400°C. The influence of final reaction temperature on products yield was investigated and some physicochemical properties...

  6. Quantitative approaches for the description of solubilities of inorganic compounds in near-critical and supercritical water

    NARCIS (Netherlands)

    Leusbrock, Ingo; Metz, Sybrand J.; Rexwinkel, Glenn; Versteeg, Geert F.

    2008-01-01

    The decreased solubility of salts in supercritical water is of great interest for industrial applications and scientific work. Several methods to quantify this decreased solubility are described and reviewed by applying them on experimental solubility data. The salts used for comparison are NaCl, N

  7. Quantitative approaches for the description of solubilities of inorganic compounds in near-critical and supercritical water

    NARCIS (Netherlands)

    Leusbrock, Ingo; Metz, Sybrand J.; Rexwinkel, Glenn; Versteeg, Geert F.

    2008-01-01

    The decreased solubility of salts in supercritical water is of great interest for industrial applications and scientific work. Several methods to quantify this decreased solubility are described and reviewed by applying them on experimental solubility data. The salts used for comparison are NaCl, Na

  8. Heat transfer characteristics of supercritical water in a tube: Application for 2D and an experimental validation

    NARCIS (Netherlands)

    Withag, J.A.M.; Sallevelt, J.L.H.P.; Brilman, D.W.F.; Bramer, E.A.; Brem, G.

    2012-01-01

    Heat transfer to water at supercritical pressures has been numerically investigated using a two-dimensional modeling approach. The simulations in a two-dimensional domain have been performed using the low-Reynolds k–ϵ turbulence model, and the IAPWS-IF97 formulation to describe the properties of wat

  9. Lignin depolymerisation in supercritical carbon dioxide/acetone/water fluid for the production of aromatic chemicals.

    Science.gov (United States)

    Gosselink, Richard J A; Teunissen, Wouter; van Dam, Jan E G; de Jong, Ed; Gellerstedt, Göran; Scott, Elinor L; Sanders, Johan P M

    2012-02-01

    Valorisation of lignin plays a key role in further development of lignocellulosic biorefinery processes the production of biofuels and bio-based materials. In the present study, organosolv hardwood and wheat straw lignins were converted in a supercritical fluid consisting of carbon dioxide/acetone/water (300-370°C, 100bar) to a phenolic oil consisting of oligomeric fragments and monomeric aromatic compounds with a total yield of 10-12% based on lignin. These yields are similar to the state-of-the-art technologies such as base-catalysed thermal processes applied for lignin depolymerisation. Addition of formic acid increases the yield of monomeric aromatic species by stabilizing aromatic radicals. Supercritical depolymerisation of wheat straw and hardwood lignin yielded monomeric compounds in different compositions with a maximum yield of 2.0% for syringic acid and 3.6% for syringol, respectively. The results of the present study showed that under the applied conditions competition occurred between lignin depolymerisation and recondensation of fragments.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

    Wet biomass (water hyacinth, banana trees, cattails, green algae, kelp, etc.) grows rapidly and abundantly around the world. However, wet biomass is not regarded as a promising feedstock for conventional thermochemical conversion processes because the cost of drying the material is too high. Prior work has shown that low concentrations of glucose (a model compound for whole biomass) and various wet biomass species (water hyacinth, algae) can be completely gasified in supercritical water at 600{degrees}C and 34.5 MPa after a 30 s residence time. But higher concentrations of glucose evidenced incomplete conversion. For this reason, flow reactors were fabricated which could accommodate packed beds of catalyst, and studies were initiated of the steam reforming (gasification) reactions in the presence of various candidate heterogeneous catalysts. The goal is to identify active catalysts for steam reforming biomass slurries in supercritical water. Soon after tests began, a suitable class of carbon-based catalysts was discovered. These catalysts effect complete (>99%) conversion of high-concentration glucose (up to 22% by weight) to a hydrogen-rich synthesis gas. High space velocities are realized [>20 (g/hr)/g], and the catalyst is stable over a period of several hours. The carbon catalyst is not expensive, and exists in a wide variety of forms and compositions. After this discovery, work has focused on four interrelated tasks: (1) tests to identify the most active form and composition of the catalyst; (2) tests employing the preferred catalyst to study the effect of feedstock composition on carbon conversion and gas composition; (3) studies of catalyst deactivation and subsequent reactivation, including the in-house synthesis of bifunctional catalysts which incorporate promoters and stabilizers; and (4) the design and fabrication of a larger, new reactor with a slurry feeder intended to handle high-concentration, wet biomass feeds.

  11. Density dependence of hydrogen bonding and the translational-orientational structural order in supercritical water: a molecular dynamics study.

    Science.gov (United States)

    Ma, Haibo; Ma, Jing

    2011-08-07

    Molecular dynamics simulation have been performed with a wide range of densities along a near critical isotherm of supercritical water (SCW) in order to study the density dependence of the structure order and hydrogen bonding (HB). It is revealed that the translational structure order is nearly invariant while the orientational tetrahedral structure order is very sensitive to the bulk density under supercritical conditions. Meanwhile, some energetically unfavorable intermediate water dimer structures are found to appear under supercritical conditions due to the reduced energy difference and the enhanced energy fluctuation. As a consequence, a general geometrical criterion or the inclusion of a energy-based criterion instead of currently widely adopted pure r(OH)-based geometric criterion is suggested to be used in the HB statistics under supercritical conditions. It is found that the average HB number per H(2)O molecule (n(HB)) reduces with the decreasing SCW bulk density although a given pair of H(2)O molecules are shown to have a stronger ability to form a hydrogen bond under lower SCW bulk densities. Accordingly, the orientational tetrahedral structure order q decreases with the reducing bulk density under supercritical conditions. However, when the fluid is dilute with ρ ≤ 0.19ρ(c) (ρ(c) = 0.322 g/cm(3)), the energy fluctuation increases sharply and the short-range order is destroyed, signifying the supercritical fluid (SCF)-gas state transition. Accordingly, the orientational tetrahedral structure order q gets reversal around ρ = 0.19ρ(c) and approaches zero under very dilute conditions. The sensitivity of the orientational order to the density implies the microscopic origin of the significant dependence of SCF's physicochemical properties on the pressure.

  12. Molecular Dynamics Simulation of Na(+)-Cl(-) Ion-Pair in Water-Methanol Mixtures under Supercritical and Ambient Conditions.

    Science.gov (United States)

    Keshri, Sonanki; Sarkar, Atanu; Tembe, B L

    2015-12-17

    Constrained molecular dynamics simulations have been performed to investigate the structure and thermodynamics of Na(+)-Cl(-) ion-pair association in water-methanol mixtures under supercritical and ambient conditions in dilute solutions. From the computed potentials of mean force (PMFs) we find that contact ion pairs (CIPs) are more stable than all other associated states of the ion pairs in both ambient and supercritical conditions. Stabilities of CIPs increase with increase in the mole fraction of methanol. In supercritical conditions, major changes in PMFs occur as we go from x(methanol) = 0.00 to x(methanol) = 0.50. The stable solvent shared ion pair (SShIP) which occurs in x(methanol) = 0.00 and 0.25, vanishes when x(methanol) is 0.50 or greater. The stabilities of these ion pairs increase with increasing temperature. Local structures around the ions are studied using the radial distribution functions, density profiles, angular distribution functions, running coordination numbers and excess coordination numbers. Preferential solvation analysis shows that both Na(+) and Cl(-) ions are preferentially solvated by water. From the calculation of enthalpies and entropies, we find that Na(+)-Cl(-) ion-pair association in water-methanol binary mixtures is endothermic and driven by entropy both in ambient as well as under supercritical conditions.

  13. Optimization of power-cycle arrangements for Supercritical Water cooled Reactors (SCWRs)

    Science.gov (United States)

    Lizon-A-Lugrin, Laure

    The world energy demand is continuously rising due to the increase of both the world population and the standard of life quality. Further, to assure both a healthy world economy as well as adequate social standards, in a relatively short term, new energy-conversion technologies are mandatory. Within this framework, a Generation IV International Forum (GIF) was established by the participation of 10 countries to collaborate for developing nuclear power reactors that will replace the present technology by 2030. The main goals of these nuclear-power reactors are: economic competitiveness, sustainability, safety, reliability and resistance to proliferation. As a member of the GIF, Canada has decided to orient its efforts towards the design of a CANDU-type Super Critical Water-cooled Reactor (SCWR). Such a system must run at a coolant outlet temperature of about 625°C and at a pressure of 25 MPa. It is obvious that at such conditions the overall efficiency of this kind of Nuclear Power Plant (NPP) will compete with actual supercritical water-power boilers. In addition, from a heat-transfer viewpoint, the use of a supercritical fluid allows the limitation imposed by Critical Heat Flux (CHF) conditions, which characterize actual technologies, to be removed. Furthermore, it will be also possible to use direct thermodynamic cycles where the supercritical fluid expands right away in a turbine without the necessity of using intermediate steam generators and/or separators. This work presents several thermodynamic cycles that could be appropriate to run SCWR power plants. Improving both thermal efficiency and mechanical power constitutes a multi-objective optimization problem and requires specific tools. To this aim, an efficient and robust evolutionary algorithm, based on genetic algorithm, is used and coupled to an appropriate power plant thermodynamic simulation model. The results provide numerous combinations to achieve a thermal efficiency higher than 50% with a

  14. Measurement of polychlorinated biphenyls in solid waste such as transformer insulation paper by supercritical fluid extraction and gas chromatography electron capture detection.

    Science.gov (United States)

    Chikushi, Hiroaki; Fujii, Yuka; Toda, Kei

    2012-09-21

    In this work, a method for measuring polychlorinated biphenyls (PCBs) in contaminated solid waste was investigated. This waste includes paper that is used in electric transformers to insulate electric components. The PCBs in paper sample were extracted by supercritical fluid extraction and analyzed by gas chromatography-electron capture detection. The recoveries with this method (84-101%) were much higher than those with conventional water extraction (0.08-14%), and were comparable to those with conventional organic solvent extraction. Limit of detection was 0.0074 mg kg(-1) and measurable up to 2.5 mg kg(-1) for 0.5 g of paper sample. Data for real insulation paper by the proposed method agreed well with those by the conventional organic solvent extraction. Extraction from wood and concrete was also investigated and good performance was obtained as well as for paper samples. The supercritical fluid extraction is simpler, faster, and greener than conventional organic solvent extraction. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Percolation line, response functions, and Voronoi polyhedra analysis in supercritical water

    Directory of Open Access Journals (Sweden)

    J. Škvor

    2012-06-01

    Full Text Available The problem of a physical relevance (meaning of percolation in supercritical fluids is addressed considering a primitive model of water. Two different criteria, physical and configurational, are used for the cluster definition in Monte Carlo simulations over a range of pressures to determine the percolation line and skewness, and a theoretical analytic equation of state is used to evaluate response functions. It is found that both criteria yield practically the same percolation line. However, unlike the findings for simple fluids, the loci of the response function extrema exhibit density/pressure dependence quite different from that of the percolation line. The only potential coincidence between the loci of the extrema of a thermodynamic property and a detectable structural change is found for the coefficient of isothermal compressibility and Voronoi neighbors distribution skewness maximum.

  16. COD Removal Efficiencies of Some Aromatic Compounds in Supercritical Water Oxidation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Some aromatic compounds, phenol, aniline and nitrobenzene, were oxidized in supercritical water. It was experimentally found that the chemical oxygen demand (COD) removal efficiency of these organic compounds can achieve a high level more than 90% in a short residence time at temperatures high enough. As temperature, pressure and residence time increase, the COD removal efficiencies of the organic compounds would all increase. It is also found that temperature and residence time offer greater influences on the oxidation process than pressure. The difficulty in oxidizing these three compounds is in the order of nitrobenzene > aniline > Phenol. In addition, it is extremely difficult to oxidize aniline and nitrobenzene to CO2 and H2O at the temperature lower than 873.15 K and 923.15 K, respectively. Only at the temperature higher than 873.15 K and 923.15 K, respectively, the COD removal efficiencies of 90% of aniline and nitrobenzene can be achieved.

  17. Supercritical water oxidation of a model fecal sludge without the use of a co-fuel.

    Science.gov (United States)

    Miller, A; Espanani, R; Junker, A; Hendry, D; Wilkinson, N; Bollinger, D; Abelleira-Pereira, J M; Deshusses, M A; Inniss, E; Jacoby, W

    2015-12-01

    A continuous supercritical water oxidation reactor was designed and constructed to investigate the conversion of a feces simulant without the use of a co-fuel. The maximum reactor temperature and waste conversion was determined as a function of stoichiometric excess of oxygen in order to determine factor levels for subsequent investigation. 48% oxygen excess showed the highest temperature with full conversion. Factorial analysis was then used to determine the effects of feed concentration, oxygen excess, inlet temperature, and operating pressure on the increase in the temperature of the reacting fluid as well as a newly defined non-dimensional number, NJa representing heat transfer efficiency. Operating pressure and stoichiometric excess oxygen were found to have the most significant impacts on NJa. Feed concentration had a significant impact on fluid temperature increase showing an average difference of 46.4°C between the factorial levels.

  18. A Review of Laboratory-Scale Research on Upgrading Heavy Oil in Supercritical Water

    Directory of Open Access Journals (Sweden)

    Ning Li

    2015-08-01

    Full Text Available With the growing demand for energy and the depletion of conventional crude oil, heavy oil in huge reserve has attracted extensive attention. However, heavy oil cannot be directly refined by existing processes unless they are upgraded due to its complex composition and high concentration of heteroatoms (N, S, Ni, V, etc.. Of the variety of techniques for heavy oil upgrading, supercritical water (SCW is gaining popularity because of its excellent ability to convert heavy oil into valued, clean light oil by the suppression of coke formation and the removal of heteroatoms. Based on the current status of this research around the world, heavy oil upgrading in SCW is summarized from three aspects: Transformation of hydrocarbons, suppression of coke, and removal of heteroatoms. In this work, the challenge and future development of the orientation of upgrading heavy oil in SCW are pointed out.

  19. A parametric study on supercritical water gasification of Laminaria hyperborea: a carbohydrate-rich macroalga.

    Science.gov (United States)

    Cherad, Ramzi; Onwudili, Jude A; Williams, Paul T; Ross, Andrew B

    2014-10-01

    The potential of supercritical water gasification (SCWG) of macroalgae for hydrogen and methane production has been investigated in view of the growing interest in a future macroalgae biorefinery concept. The compositions of syngas from the catalytic SCWG of Laminaria hyperborea under varying parameters including catalyst loading, feed concentration, hold time and temperature have been investigated. Their effects on gas yields, gasification efficiency and energy recovery are presented. Results show that the carbon gasification efficiencies increased with reaction temperature, reaction hold time and catalyst loading but decreased with increasing feed concentrations. In addition, the selectivity towards hydrogen and/or methane production from the SCWG tests could be controlled by the combination of catalysts and varying reaction conditions. For instance, Ru/Al2O3 gave highest carbon conversion and highest methane yield of up to 11 mol/kg, whilst NaOH produced highest hydrogen yield of nearly 30 mol/kg under certain gasification conditions.

  20. Oxidation kinetics of model compounds of metabolic waste in supercritical water

    Science.gov (United States)

    Webley, Paul A.; Holgate, Henry R.; Stevenson, David M.; Tester, Jefferson W.

    1990-01-01

    In this NASA-funded study, the oxidation kinetics of methanol and ammonia in supercritical water have been experimentally determined in an isothermal plug flow reactor. Theoretical studies have also been carried out to characterize key reaction pathways. Methanol oxidation rates were found to be proportional to the first power of methanol concentration and independent of oxygen concentration and were highly activated with an activation energy of approximately 98 kcal/mole over the temperature range 480 to 540 C at 246 bar. The oxidation of ammonia was found to be catalytic with an activation energy of 38 kcal/mole over temperatures ranging from 640 to 700 C. An elementary reaction model for methanol oxidation was applied after correction for the effect of high pressure on the rate constants. The conversion of methanol predicted by the model was in good agreement with experimental data.

  1. Supercritical water gasification of sewage sludge: gas production and phosphorus recovery.

    Science.gov (United States)

    Acelas, Nancy Y; López, Diana P; Brilman, D W F Wim; Kersten, Sascha R A; Kootstra, A Maarten J

    2014-12-01

    In this study, the feasibility of the gasification of dewatered sewage sludge in supercritical water (SCW) for energy recovery combined with P-recovery from the solid residue generated in this process was investigated. SCWG temperature (400°C, 500°C, 600°C) and residence time (15min, 30min, 60min) were varied to investigate their effects on gas production and the P recovery by acid leaching. The results show that the dry gas composition for this uncatalyzed gasification of sewage sludge in SCW mainly comprised of CO2, CO, CH4, H2, and some C2-C3 compounds. Higher temperatures and longer residence times favored the production of H2 and CH4. After SCWG, more than 95% of the P could be recovered from the solid residue by leaching with acids. SCWG combined with acid leaching seems an effective method for both energy recovery and high P recovery from sewage sludge.

  2. Hydrogen production by supercritical water gasification of wastewater from food waste treatment processes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, In-Gu [Korea Institute of Energy Research (Korea, Republic of)

    2010-07-01

    Korean food wastes have high moisture content (more than 85 wt%) and their major treatment processes such as drying or biological fermentations generate concentrated organic wastewater (CODs of about 100,000 mgO{sub 2}/L). For obtaining both wastewater treatment and hydrogen production from renewable resources, supercritical water gasification (SCWG) of the organic wastewater was carried out in this work. The effect of catalyst, reaction temperature, and reactor residence time on COD destruction and composition of gas products was examined. As a result, a SCWG of the wastewater over Ni- Y/activated charcoal at 700 C, 28 MPa yielded 99 % COD destruction and hydrogen-rich gas production (45 vol% H{sub 2}). A liquid-phase thermal pretreatment to destroy solid particles from the wastewater was proposed for more effective operation of the SCWG system. (orig.)

  3. Corrosion behavior of a 14Cr-ODS steel in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Hu, H.L. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhou, Z.J., E-mail: zhouzhangjianustb@163.com [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Liao, L. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, L.F. [School of Nuclear Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China); Wang, M.; Li, S.F.; Ge, C.C. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2013-06-15

    The corrosion behavior of a 14Cr-ODS steel in the supercritical water was investigated using a variety of characterization techniques. Compared with 316L austenitic steel, the 14Cr-ODS steel had better corrosion resistant property. As the increasing of the exposure time, the weight gain increased, but the corrosion rates decreased. The curve of weight gain as a function of time followed a parabolic law. The general weight gain was 0.3476 mg/(dm{sup 2} h). A triple layer was observed which consisted of an outer layer, an inner layer and a diffusion layer. The outer layer was iron rich and contained Fe{sub 3}O{sub 4}, on which pores were observed. The inner layer and diffusion layer contained mainly (Fe,Cr{sub 2})O{sub 4}. The oxidation mechanism was also discussed.

  4. Partial oxidation of landfill leachate in supercritical water: Optimization by response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yanmeng; Wang, Shuzhong; Xu, Haidong; Guo, Yang; Tang, Xingying

    2015-09-15

    Highlights: • Partial oxidation of landfill leachate in supercritical water was investigated. • The process was optimized by Box–Behnken design and response surface methodology. • GY{sub H2}, TRE and CR could exhibit up to 14.32 mmol·gTOC{sup −1}, 82.54% and 94.56%. • Small amounts of oxidant can decrease the generation of tar and char. - Abstract: To achieve the maximum H{sub 2} yield (GY{sub H2}), TOC removal rate (TRE) and carbon recovery rate (CR), response surface methodology was applied to optimize the process parameters for supercritical water partial oxidation (SWPO) of landfill leachate in a batch reactor. Quadratic polynomial models for GY{sub H2}, CR and TRE were established with Box–Behnken design. GY{sub H2}, CR and TRE reached up to 14.32 mmol·gTOC{sup −1}, 82.54% and 94.56% under optimum conditions, respectively. TRE was invariably above 91.87%. In contrast, TC removal rate (TR) only changed from 8.76% to 32.98%. Furthermore, carbonate and bicarbonate were the most abundant carbonaceous substances in product, whereas CO{sub 2} and H{sub 2} were the most abundant gaseous products. As a product of nitrogen-containing organics, NH{sub 3} has an important effect on gas composition. The carbon balance cannot be reached duo to the formation of tar and char. CR increased with the increase of temperature and oxidation coefficient.

  5. Estimation of Oxidation Kinetics and Oxide Scale Void Position of Ferritic-Martensitic Steels in Supercritical Water

    Directory of Open Access Journals (Sweden)

    Li Sun

    2017-01-01

    Full Text Available Exfoliation of oxide scales from high-temperature heating surfaces of power boilers threatened the safety of supercritical power generating units. According to available space model, the oxidation kinetics of two ferritic-martensitic steels are developed to predict in supercritical water at 400°C, 500°C, and 600°C. The iron diffusion coefficients in magnetite and Fe-Cr spinel are extrapolated from studies of Backhaus and Töpfer. According to Fe-Cr-O ternary phase diagram, oxygen partial pressure at the steel/Fe-Cr spinel oxide interface is determined. The oxygen partial pressure at the magnetite/supercritical water interface meets the equivalent oxygen partial pressure when system equilibrium has been attained. The relative error between calculated values and experimental values is analyzed and the reasons of error are suggested. The research results show that the results of simulation at 600°C are approximately close to experimental results. The iron diffusion coefficient is discontinuous in the duplex scale of two ferritic-martensitic steels. The simulation results of thicknesses of the oxide scale on tubes (T91 of final superheater of a 600 MW supercritical boiler are compared with field measurement data and calculation results by Adrian’s method. The calculated void positions of oxide scales are in good agreement with a cross-sectional SEM image of the oxide layers.

  6. SUPERCRITICAL WATER PARTIAL OXIDATION PHASE I - PILOT-SCALE TESTING / FEASIBILITY STUDIES FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    SPRITZER,M; HONG,G

    2005-01-01

    Under Cooperative Agreement No. DE-FC36-00GO10529 for the Department of Energy, General Atomics (GA) is developing Supercritical Water Partial Oxidation (SWPO) as a means of producing hydrogen from low-grade biomass and other waste feeds. The Phase I Pilot-scale Testing/Feasibility Studies have been successfully completed and the results of that effort are described in this report. The Key potential advantages of the SWPO process is the use of partial oxidation in-situ to rapidly heat the gasification medium, resulting in less char formation and improved hydrogen yield. Another major advantage is that the high-pressure, high-density aqueous environment is ideal for reaching and gasifying organics of all types. The high water content of the medium encourages formation of hydrogen and hydrogen-rich products and is especially compatible with high water content feeds such as biomass materials. The high water content of the medium is also effective for gasification of hydrogen-poor materials such as coal. A versatile pilot plant for exploring gasification in supercritical water has been established at GA's facilities in San Diego. The Phase I testing of the SWPO process with wood and ethanol mixtures demonstrated gasification efficiencies of about 90%, comparable to those found in prior laboratory-scale SCW gasification work carreid out at the University of Hawaii at Manoa (UHM) as well as other biomass gasification experience with conventional gasifiers. As in the prior work at UHM, a significant amount of the hydrogen found in the gas phase products is derived from the water/steam matrix. The studies at UHM utilized an indirectly heated gasifier with an acitvated carbon catalyst. In contrast, the GA studies utilized a directly heated gasifier without catalyst, plus a surrogate waste fuel. Attainment of comparable gasification efficiencies without catalysis is an important advancement for the GA process, and opens the way for efficient hydrogen production from low

  7. LABORATORY EQUIPMENT FOR AUTOTHERMAL REFORMING OF ORGANIC MATTER IN SUPERCRITICAL WATER

    Directory of Open Access Journals (Sweden)

    Matúš Gajdoš

    2014-02-01

    Full Text Available The ability of water to dissolve organic substances is very limited. However, its ability to dissolve them changes if pressure and temperature values reach the so-called critical point (p = 22.06MPa, T = 373.95 °C. Fluid water in this state is called supercritical water (SCW, and values of its physical properties are included among the values of such properties for liquid phase and gaseous phase. Various types of organic matter can be treated in SCW, and it is especially useful for materials that cannot be treated cost-effectively with conventional technologies (incineration, etc.. Suitable input materials are mainly industrial waste or biomass with high water content. Conventional processing of these materials requires energy-intensive drying or densification. Processing the inputs in SCW completely removes these problems, since sufficient water content is a prerequisite for creating a suitable environment for efficient operation of the system. In this paper, glycerol as a by-product of alternative fuel production was chosen for evaluation in the SCW autothermal reforming cycle. The paper analyses the influence of several processing parameters on the operation of model laboratory equipment.

  8. Behavior of water in supercritical CO2: adsorption and capillary condensation in porous media

    Science.gov (United States)

    Heath, J. E.; Bryan, C. R.; Dewers, T. A.; Wang, Y.

    2011-12-01

    The chemical potential of water in supercritical CO2 (scCO2) may play an important role in water adsorption, capillary condensation, and evaporation under partially saturated conditions at geologic CO2 storage sites, especially if initially anhydrous CO2 is injected. Such processes may affect residual water saturations, relative permeability, shrink/swell of clays, and colloidal transport. We have developed a thermodynamic model of water or brine film thickness as a function of water relative humidity in scCO2. The model is based on investigations of liquid water configuration in the vadose zone and uses the augmented Young-Laplace equation, which incorporates both adsorptive and capillary components. The adsorptive component is based on the concept of disjoining pressure, which reflects force per area normal to the solid and water/brine-scCO2 interfaces. The disjoining pressure includes van der Waals, electrostatic, and structural interactions. The van der Waals term includes the effects of mutual dissolution of CO2 and water in the two fluid phases on partial molar volumes, dielectric coefficients, and refractive indices. Our approach treats the two interfaces as asymmetric surfaces in terms of charge densities and electrostatic potentials. We use the disjoining pressure isotherm to evaluate the type of wetting (e.g., total or partial wetting) for common reservoir and caprock minerals and kerogen. The capillary component incorporates water activity and is applied to simple pore geometries with slits and corners. Finally, we compare results of the model to a companion study by the coauthors on measurement of water adsorption to mineral phases using a quartz-crystal microbalance. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  9. Experimental investigation of inclination effect on subcritical and supercritical water flows heat transfer in an internally ribbed tube

    Science.gov (United States)

    Taklifi, Alireza; Akhavan-Behabadi, Mohammad Ali; Hanafizadeh, Pedram; Aliabadi, Abbas

    2017-02-01

    The effect of various inclination angles on heat transfer of water at subcritical and supercritical operating pressures is investigated experimentally. The test section was a SA213T12 steel six-headed internally ribbed tube with minimum inner diameter of 19.5 mm. The operating test pressures were 15, 21.5, 22.5, 25 and 28 MPa, the mass flux was 800 kg/m2 s and the heat flux was 400 kW/m2. To keep the mass flux to heat flux ratio equal to 2 kg/kJ. These operating conditions covered subcritical, near critical and supercritical water flows and also refers to low mass flux conditions. The inclination angles were 5, 20, 30, 45 and 90 (vertical) degrees respecting to horizontal plane. The heat flux was kept constant along the test tube by controlling of electric heating. As a result the inner wall temperature and convective heat transfer coefficient variations with respect to heated length and bulk enthalpy of fluid were considered in order to study the heat transfer characteristics of various flows at different inclinations. The corresponding correlation for heat transfer coefficient was developed which is applicable for wide range of inclination angles. The heat transfer enhancement was obvious for inclination angles other than 90°, however, this effect was more obvious in 5° and 20° in some operating conditions. It was also concluded that the effect of inclination on heat transfer of water was more considerable in subcritical flow conditions than supercritical ones. Also, it was observed that angle of 20° seems to be the best for subcritical flows from heat transfer point of view, but for supercritical flows 5 or 45 seem to be more advantageous. These differences could be related to different heat transfer mechanisms of subcritical and supercritical flows.

  10. Experimental investigation of inclination effect on subcritical and supercritical water flows heat transfer in an internally ribbed tube

    Science.gov (United States)

    Taklifi, Alireza; Akhavan-Behabadi, Mohammad Ali; Hanafizadeh, Pedram; Aliabadi, Abbas

    2016-06-01

    The effect of various inclination angles on heat transfer of water at subcritical and supercritical operating pressures is investigated experimentally. The test section was a SA213T12 steel six-headed internally ribbed tube with minimum inner diameter of 19.5 mm. The operating test pressures were 15, 21.5, 22.5, 25 and 28 MPa, the mass flux was 800 kg/m2 s and the heat flux was 400 kW/m2. To keep the mass flux to heat flux ratio equal to 2 kg/kJ. These operating conditions covered subcritical, near critical and supercritical water flows and also refers to low mass flux conditions. The inclination angles were 5, 20, 30, 45 and 90 (vertical) degrees respecting to horizontal plane. The heat flux was kept constant along the test tube by controlling of electric heating. As a result the inner wall temperature and convective heat transfer coefficient variations with respect to heated length and bulk enthalpy of fluid were considered in order to study the heat transfer characteristics of various flows at different inclinations. The corresponding correlation for heat transfer coefficient was developed which is applicable for wide range of inclination angles. The heat transfer enhancement was obvious for inclination angles other than 90°, however, this effect was more obvious in 5° and 20° in some operating conditions. It was also concluded that the effect of inclination on heat transfer of water was more considerable in subcritical flow conditions than supercritical ones. Also, it was observed that angle of 20° seems to be the best for subcritical flows from heat transfer point of view, but for supercritical flows 5 or 45 seem to be more advantageous. These differences could be related to different heat transfer mechanisms of subcritical and supercritical flows.

  11. A universal salt model based on under-ground precipitation of solid salts due to supercritical water `out-salting'

    Science.gov (United States)

    Rueslåtten, H.; Hovland, M. T.

    2010-12-01

    One of the common characteristics of planets Earth and Mars is that both host water (H2O) and large accumulations of salt. Whereas Earth’s surface-environment can be regarded as ‘water-friendly’ and ‘salt hostile’, the reverse can be said for the surface of Mars. This is because liquid water is stable on Earth, and the atmosphere transports humidity around the globe, whereas on planet Mars, liquid water is unstable, rendering the atmosphere dry and, therefore, ‘salt-friendly’. The riddle as to how the salt accumulated in various locations on those two planets, is one of long-lasting and great debate. The salt accumulations on Earth are traditionally termed ‘evaporites’, meaning that they formed as a consequence of the evaporation of large masses of seawater. How the accumulations on Mars formed is much harder to explain, as an ocean only existed briefly. Although water molecules and OH-groups may exist in abundance in bound form (crystal water, adsorbed water, etc.), the only place where free water is expected to be stable on Mars is within underground faults, fractures, and crevices. Here it likely occurs as brine or in the form of ice. Based on these conditions, a key to understanding the accumulation of large deposits of salt on both planets is linked to how brines behave in the subsurface when pressurized and heated beyond their supercritical point. At depths greater than about 3 km (P>300 bars) water will no longer boil in a steam phase. Rather, it becomes supercritical and will attain the phase of supercritical water vapor (SCRIW) with a specific gravity of typically 0.3 g/cm3. An important characteristic of SCRIW is its inability to dissolve the common sea salts. The salt dissolved in the brines will therefore precipitate as solid particles when brines (seawater on the Earth) move into the supercritical P&T-domain (T>400°C, P>300 bars). Numerical modeling of a hydrothermal system in the Atlantis II Deep of the Red Sea indicates that a

  12. Exploration of the effect of process variables on the production of high-value fuel gas from glucose via supercritical water gasification.

    Science.gov (United States)

    Hendry, Doug; Venkitasamy, Chandrasekar; Wilkinson, Nikolas; Jacoby, William

    2011-02-01

    A new continuous supercritical water gasification reactor was designed to investigate glucose gasification in supercritical water at high temperatures and low residence times. A 2(3) full factorial experiment was performed to determine the effects of feed concentration, temperature, and residence time on glucose gasification. The temperature levels (750°C and 800°C) were higher than ever used, while the residence times (4 and 6.5s) were shorter than ever used in previous supercritical water gasification studies. The reactor proved capable of attaining higher gasification rates than previously shown with high efficiencies and yields. In addition, the glucose gasification reaction was modeled by estimating activation energy and reaction order of glucose gasification in supercritical water.

  13. Packed column supercritical fluid chromatography of hydrophilic analytes via water-rich modifiers.

    Science.gov (United States)

    Taylor, Larry T

    2012-08-10

    The use of additives to dramatically extend the range of solute polarity amenable to CO(2) based supercritical fluid chromatography (pcSFC) was predicted over 20 years ago. At that time additives were predicted to have multiple functions such as enhancement of mobile phase solvating power, ion suppression, and ion pairing. The adsorption of mobile phase components on the stationary phase causing a modification of its surface was predicted, but the implications for separations were not defined. Reports published in the late 1980s showed that while water could not function as a primary modifier due to it poor solubility in carbon dioxide, its use as an additive was more promising. The past decade has seen very little published work concerning water and pcSFC. Now reports are beginning to appear that demonstrate enhanced selectivity with water, and application of the technology to polypeptide salts, drug molecules, and nucleobases. This review attempts to bridge the past with the present. As evidenced by the studies described in this review, water may offer much potential as an additive in that it could (a) enhance the solvating power of the mobile phase, (b) introduce HILIC-like analyte partitioning, (c) simplify preparative purifications, and (d) offer a more mass spectrometrically compatible interface.

  14. Nickel removal from nickel-5,10,15,20-tetraphenylporphine using supercritical water in absence of catalyst: a basic study.

    Science.gov (United States)

    Mandal, Pradip Chandra; Wahyudiono; Sasaki, Mitsuru; Goto, Motonobu

    2011-03-15

    Reactions of nickel-5,10,15,20-tetraphenylporphine (Ni-TPP) were studied in supercritical water in the presence of toluene without the addition of any catalyst, H(2) or H(2)S that is called a green process. The objective of this study was to remove nickel from Ni-TPP, the most common metal compound present in heavy crude, in high extent at low reaction time. All experiments were carried out in an 8.8 mL batch reactor fabricated from hastelloy C-276. The ability of supercritical water (SCW) to remove nickel from Ni-TPP was studied at temperatures of 450-490 °C and water partial pressures of 25-35 MPa. Water partial pressure had no effect on overall conversion at temperatures of 450 °C and a reaction time of 60 min. The overall Ni-TPP conversion was 89.80%, a figure above that of previous catalytic studies. The percentage of nickel removal was estimated as a function of reaction time and temperature. It were temperature 490 °C and pressure 25 MPa at reaction time 90 min where 65.68% nickel were removed by the action of SCW and toluene, as a co-solvent. It was determined that Ni-TPP undergoes a series of reactions, ending in demetallation and ring fragmentation. The obtained results suggest that supercritical water has a capability to remove nickel from Ni-TPP.

  15. Packed column supercritical fluid chromatography using stainless steel particles and water as a stationary phase.

    Science.gov (United States)

    Murakami, Jillian N; Thurbide, Kevin B

    2015-09-15

    Stainless steel (SS) particles were demonstrated as a novel useful support for a water stationary phase in packed column supercritical fluid chromatography using a CO2 mobile phase. Separations employed flame ionization detection, and the system was operated over a range of temperatures and pressures. Retention times reproduced well with RSD values of 2.6% or less. Compared to analogous separations employing a water stationary phase coated onto a SS capillary column, the packed column method provided separations that were about 10× faster, with nearly 8-fold larger analyte retention factors, while maintaining good peak shape and comparable column efficiency. Under normal operating conditions, the packed column contains about 131 ± 4 μL/m of water phase (around a 5% m/m coating), which is over 25× greater than the capillary column and also affords it a 20-fold larger sample capacity. Several applications of the packed column system are examined, and the results indicate that it is a useful alternative to the capillary column mode, particularly where analyte loads or sample matrix interference is a concern. Given its high sample capacity, this packed column method may also be useful to explore on a more preparative scale in the future.

  16. Energy conversion of biomass with supercritical and subcritical water using large-scale plants.

    Science.gov (United States)

    Okajima, Idzumi; Sako, Takeshi

    2014-01-01

    Exploiting unused or waste biomass as an alternative fuel is currently receiving much attention because of the potential reductions in CO2 emissions and the lower cost in comparison to expensive fossil fuels. If we are to use biomass domestically or industrially, we must be able to convert biomass to high-quality and easy-to-use liquid, gas, or solid fuels that have high-calorific values, low moisture and ash contents, uniform composition, and suitable for stored over long periods. In biomass treatment, hot and high-pressure water including supercritical and subcritical water is an excellent solvent, as it is clean and safe and its action on biomass can be optimized by varying the temperature and pressure. In this article, the conversion of waste biomass to fuel using hot and high-pressure water is reviewed, and the following examples are presented: the production of large amounts of hydrogen from waste biomass, the production of cheap bioethanol from non-food raw materials, and the production of composite powder fuel from refractory waste biomass in the rubble from the Great East Japan Earthquake. Several promising techniques for the conversion of biomass have been demonstrated in large-scale plants and commercial deployment is expected in the near future. Copyright © 2013. Published by Elsevier B.V.

  17. Hydrothermal liquefaction of Spirulina and Nannochloropsis salina under subcritical and supercritical water conditions.

    Science.gov (United States)

    Toor, Saqib S; Reddy, Harvind; Deng, Shuguang; Hoffmann, Jessica; Spangsmark, Dorte; Madsen, Linda B; Holm-Nielsen, Jens Bo; Rosendahl, Lasse A

    2013-03-01

    Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220–375 °C, 20–255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid residue, and recycling process water for algae cultivation. GC–MS, elemental analyzer, FT-IR, calorimeter and nutrient analysis were used to analyze bio-crude, lipid-extracted algae and water samples produced in the hydrothermal liquefaction process. The highest bio-crude yield of 46% was obtained on N. salina at 350 °C and 175 bar. For S. platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for N. salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae solid residue sample obtained in the hydrothermal liquefaction process contains a high level of proteins.

  18. Supercritical water treatment for cello-oligosaccharide production from microcrystalline cellulose.

    Science.gov (United States)

    Tolonen, Lasse K; Juvonen, Minna; Niemelä, Klaus; Mikkelson, Atte; Tenkanen, Maija; Sixta, Herbert

    2015-01-12

    Microcrystalline cellulose was treated in supercritical water at 380 °C and at a pressure of 250 bar for 0.2, 0.4, and 0.6s. The yield of the ambient-water-insoluble precipitate and its average molar mass decreased with an extended treatment time. The highest yield of 42 wt% for DP2-9 cello-oligosaccharides was achieved after the 0.4s treatment. The reaction products included also 11 wt% ambient-water-insoluble precipitate with a DP(w) of 16, and 6.1 wt% monomeric sugars, and 37 wt% unidentified degradation products. Oligo- and monosaccharide-derived dehydration and retro-aldol fragmentation products were analyzed via a combination of HPAEC-PAD-MS, ESI-MS/MS, and GC-MS techniques. The total amount of degradation products increased with treatment time, and fragmented (glucosyl(n)-erythrose, glucosyl(n)-glycolaldehyde), and dehydrated (glucosyl(n)-levoglucosan) were identified as the main oligomeric degradation products from the cello-oligosaccharides.

  19. Supercritical fluid particle design for poorly water-soluble drugs (review).

    Science.gov (United States)

    Sun, Yongda

    2014-01-01

    Supercritical fluid particle design (SCF PD) offers a number of routes to improve solubility and dissolution rate for enhancing the bioavailability of poorly water-soluble drugs, which can be adopted through an in-depth knowledge of SCF PD processes and the molecular properties of active pharmaceutical ingredients (API) and drug delivery system (DDS). Combining with research experiences in our laboratory, this review focuses on the most recent development of different routes (nano-micron particles, polymorphic particles, composite particles and bio-drug particles) to improve solubility and dissolution rate of poorly water-soluble drugs, covering the fundamental concept of SCF and the principle of SCF PD processes which are typically used to control particle size, shape, morphology and particle form and hence enable notable improvement in the dissolution rate of the poorly water-soluble drugs. The progress of the industrialization of SCF PD processes in pharmaceutical manufacturing environment with scaled-up plant under current good manufacturing process (GMP) specification is also considered in this review.

  20. Preliminary Development of Thermal Power Calculation Code H-Power for a Supercritical Water Reactor

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2014-01-01

    Full Text Available SCWR (Supercritical Water Reactor is one of the promising Generation IV nuclear systems, which has higher thermal power efficiency than current pressurized water reactor. It is necessary to perform the thermal equilibrium and thermal power calculation for the conceptual design and further monitoring and calibration of the SCWR. One visual software named H-Power was developed to calculate thermal power and its uncertainty of SCWR, in which the advanced IAPWS-IF97 industrial formulation was used to calculate the thermodynamic properties of water and steam. The ISO-5167-4: 2003 standard was incorporated in the code as the basis of orifice plate to compute the flow rate. New heat balance model and uncertainty estimate have also been included in the code. In order to validate H-Power, an assessment was carried out by using data published by US and Qinshan Phase II. The results showed that H-Power was able to estimate the thermal power of SCWR.

  1. Effect of supercritical water treatment on porous structure, liquid-phase adsorption and regeneration characteristics of activated anthracite

    Energy Technology Data Exchange (ETDEWEB)

    Tanthapanichakoon, W.; Sittipraneed, S.; Japthong, P.; Charinpanitkul, T.; Boon-Amnuayvitaya, V.; Nakagawa, K.; Tamon, H. [National Nanotechnological Centre, Pathumthani (Thailand)

    2006-06-15

    Microporous activated anthracite was produced from waste anthracite powders by the conventional steam activation. The activated anthracite was also treated by supercritical water reaction (SWR) by using distilled water and hydrogen peroxide solution as a liquid medium for SWR treatment. It was found that SWR treatment can improve the mesoporosity of the activated anthracite though the micropore volume was reduced by the treatment. In liquid-phase adsorption and supercritical water regeneration studies, phenol and organic dye RED 31 were selected as the representative adsorbates. The adsorption and regeneration characteristics of activated anthracite were compared with those of a commercial activated carbon. The results indicate that the activated anthracite prepared showed comparable phenol adsorption capacity but significantly lower dye adsorption capacity than the commercial one. However, supercritical water regeneration efficiency was remarkably high. The first/second regeneration efficiencies of commercial activated carbon and activated anthracite exhausted with phenol were 55/55 and 65/65%, respectively, and in the case of RED 31, 78/79 and 338/317%, respectively, with losses of activated carbon less than 4% per regeneration. Because of little loss of activated carbon during successive regenerations, this SWR regeneration method was suitable for regenerating spent activated carbon or anthracite.

  2. Hydrogen bond driven chemical reactions: Beckmann rearrangement of cyclohexanone oxime into epsilon-caprolactam in supercritical water.

    Science.gov (United States)

    Boero, Mauro; Ikeshoji, Tamio; Liew, Chee Chin; Terakura, Kiyoyuki; Parrinello, Michele

    2004-05-26

    Recent experiments have shown that supercritical water (SCW) has the ability to accelerate and make selective synthetic organic reactions, thus replacing the common but environmentally harmful acid and basic catalysts. In an attempt to understand the intimate mechanism behind this observation, we analyze, via first-principles molecular dynamics, the Beckmann rearrangement of cyclohexanone oxime into epsilon-caprolactam in supercritical water, for which accurate experimental evidence has been reported. Differences in the wetting of the hydrophilic parts of the solute, enhanced by SCW, and the disrupted hydrogen bond network are shown to be crucial in triggering the reaction and in making it selective. Furthermore, the enhanced concentrations of H(+) in SCW play an important role in starting the reaction.

  3. Decomposition of prepolymers and molding materials of phenol resin in subcritical and supercritical water under an Ar atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yuichi; Tagaya, Hideyuki; Kadokawa, Junichi; Chiba, Koji [Yamagata Univ., Yonezawa, Yamagata (Japan). Dept. of Materials Science and Engineering; Asou, Tetsuo [Sumitomo Bakelite Co. Ltd., Fujieda, Shizuoka (Japan)

    1999-04-01

    Seven prepolymers of phenol resin were decomposed into their monomers such as phenol, cresols, and p-isopropylphenol by reactions at 523--703 K under an Ar atmosphere in subcritical and supercritical water. The total yield of identified products depended on the kind of prepolymers, and the maximum yield reached 78% in the reaction at 703 K for 0.5 h. The decomposition reactions were accelerated by the addition of Na{sub 2}CO{sub 3}, and the yields of identified monomers reached more than 90%. Two kinds of molding materials of phenol resin whose content of phenol resin was less than 50% were also decomposed mainly into phenol and cresols by the reaction in supercritical water.

  4. Feasibility analysis of modified AL-6XN steel for structure component application in supercritical water-cooled reactor

    Institute of Scientific and Technical Information of China (English)

    Xinggang LI; Qingzhi YAN; Rong MA; Haoqiang WANG; Changchun GE

    2009-01-01

    Modified AL-6XN austenite steel was patterned after AL-6XN superaustenitic stainless steel by introducing microalloy elements such as zirconium and titanium in order to adapt to recrystallizing thermo-mechanical treatment and further improve crevice corrosion resistance. Modified AL-6XN exhibited comparable tensile strength, and superior plasticity and impact toughness to commercial AL-6XN steel. The effects of aging behavior on corrosion resistance and impact toughness were measured to evaluate the qualification of modified AL-6XN steel as an in-core component and cladding material in a supercritical water-cooled reactor. Attention should be paid to degradation in corrosion resistance and impact toughness after aging for 50 hours when modified AL-6XN steel is considered as one of the candidate materials for in-core components and cladding tubes in supercritical water-cooled reactors.

  5. The effect of alkali on the product distribution from black liquor conversion under supercritical water.

    Science.gov (United States)

    Hawangchu, Y; Atong, D; Sricharoenchaikul, V

    2017-07-01

    Lignin in chemical pulping waste, or black liquor (BL), can be converted into various products via supercritical water gasification (SCWG). However, the inherited alkaline contents from the pulping chemicals may affect the product yields and properties. In this research, the influence of the residual alkali on the product distribution via SCWG of soda BL and kraft BL was evaluated. The SCWG was performed in a batch quartz reactor for 10 min at various temperatures (673, 773 and 873 K) and pressures (250, 300 and 400 bar). The highest hydrogen (H2) production occurred at 873 K for the soda BL. The water-gas shift reaction with sodium ions played an important part in the H2 production, while only small amounts of methane and carbon monoxide were detected. Hydrocarbons, carboxylic acids and esters were the dominant substrates in the liquid products, which denoted the potential of this method for bond cleaving of the lignin macromolecule. As a result, BL, which typically contains alkali salt, was an appropriate feedstock for the SCWG reaction to produce renewable fuel. This method not only has a positive influence on the generation of value added products from highly corrosive waste but also helps avoid some technical problems commonly encountered with direct firing in a recovery boiler.

  6. Stereoselective Determination of Tebuconazole in Water and Zebrafish by Supercritical Fluid Chromatography Tandem Mass Spectrometry.

    Science.gov (United States)

    Liu, Na; Dong, Fengshou; Xu, Jun; Liu, Xingang; Chen, Zenglong; Tao, Yan; Pan, Xinglu; Chen, XiXi; Zheng, Yongquan

    2015-07-22

    A simple and sensitive method for the enantioselective determination of tebuconazole enantiomers in water and zebrafish has been established using supercritical fluid chromatography (SFC)-MS/MS. The effects of the chiral stationary phases, mobile phase, auto back pressure regulator (ABPR) pressure, column temperature, flow rate of the mobile phase, and compensation pump solvent were evaluated. Finally, the optimal SFC-MS/MS working conditions were determined to include a CO2/MeOH mobile phase (87:13, v/v), 2.0 mL/min flow rate, 2200 psi ABPR, and 30 °C column temperature using a Chiralpak IA-3 chiral column under electrospray ionization positive mode. The modified QuEChERS method was applied to water and zebrafish samples. The mean recoveries for the tebuconazole enantiomers were 79.8-108.4% with RSDs ≤ 7.0% in both matrices. The LOQs ranged from 0.24 to 1.20 μg/kg. The developed analytical method was further validated by application to the analysis of authentic samples.

  7. Recovery of metals from waste printed circuit boards by supercritical water pre-treatment combined with acid leaching process.

    Science.gov (United States)

    Xiu, Fu-Rong; Qi, Yingying; Zhang, Fu-Shen

    2013-05-01

    Waste printed circuit boards (PCBs) contain a large number of metals such as Cu, Sn, Pb, Cd, Cr, Zn, and Mn. In this work, an efficient and environmentally friendly process for metals recovery from waste PCBs by supercritical water (SCW) pre-treatment combined with acid leaching was developed. In the proposed process, waste PCBs were pre-treated by SCW, then the separated solid phase product with concentrated metals was subjected to an acid leaching process for metals recovery. The effect of SCW pre-treatment on the recovery of different metals from waste PCBs was investigated. Two methods of SCW pre-treatment were studied: supercritical water oxidation (SCWO) and supercritical water depolymerization (SCWD). Experimental results indicated that SCWO and SCWD pre-treatment had significant effect on the recovery of different metals. SCWO pre-treatment was highly efficient for enhancing the recovery of Cu and Pb, and the recovery efficiency increased significantly with increasing pre-treatment temperature. The recovery efficiency of Cu and Pb for SCWO pre-treatment at 420°C was 99.8% and 80%, respectively, whereas most of the Sn and Cr were immobilized in the residue. The recovery of all studied metals was enhanced by SCWD pre-treatment and increased along with pre-treatment temperature. Up to 90% of Sn, Zn, Cr, Cd, and Mn could be recovered for SCWD pre-treatment at 440°C. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Reacting flow simulations of supercritical water oxidation of PCB-contaminated transformer oil in a pilot plant reactor

    Directory of Open Access Journals (Sweden)

    V. Marulanda

    2011-06-01

    Full Text Available The scale-up of a supercritical water oxidation process, based on recent advancements in kinetic aspects, reactor configuration and optimal operational conditions, depends on the research and development of simulation tools, which allow the designer not only to understand the complex multiphysics phenomena that describe the system, but also to optimize the operational parameters to attain the best profit for the process and guarantee its safe operation. Accordingly, this paper reports a multiphysics simulation with the CFD software Comsol Multiphysics 3.3 of a pilot plant reactor for the supercritical water oxidation of a heavily PCB-contaminated mineral transformer oil. The proposed model was based on available information for the kinetic aspects of the complex mixture and the optimal operational conditions obtained in a lab-scale continuous supercritical water oxidation unit. The pilot plant simulation results indicate that it is not feasible to scale-up directly the optimal operational conditions obtained in the isothermal lab-scale experiments, due to the excess heat released by the exothermic oxidation reactions that result in outlet temperatures higher than 600°C, even at reactor inlet temperatures as low as 400°C. Consequently, different alternatives such as decreasing organic flowrates or a new reactor set-up with multiple oxidant injections should be considered to guarantee a safe operation.

  9. Numerical analysis of flow instability in the water wall of a supercritical CFB boiler with annular furnace

    Science.gov (United States)

    Xie, Beibei; Yang, Dong; Xie, Haiyan; Nie, Xin; Liu, Wanyu

    2016-08-01

    In order to expand the study on flow instability of supercritical circulating fluidized bed (CFB) boiler, a new numerical computational model considering the heat storage of the tube wall metal was presented in this paper. The lumped parameter method was proposed for wall temperature calculation and the single channel model was adopted for the analysis of flow instability. Based on the time-domain method, a new numerical computational program suitable for the analysis of flow instability in the water wall of supercritical CFB boiler with annular furnace was established. To verify the code, calculation results were respectively compared with data of commercial software. According to the comparisons, the new code was proved to be reasonable and accurate for practical engineering application in analysis of flow instability. Based on the new program, the flow instability of supercritical CFB boiler with annular furnace was simulated by time-domain method. When 1.2 times heat load disturbance was applied on the loop, results showed that the inlet flow rate, outlet flow rate and wall temperature fluctuated with time eventually remained at constant values, suggesting that the hydrodynamic flow was stable. The results also showed that in the case of considering the heat storage, the flow in the water wall is easier to return to stable state than without considering heat storage.

  10. Numerical analysis of thermal-hydraulic behavior of supercritical water in vertical upward/downward flow channels

    Institute of Scientific and Technical Information of China (English)

    GU Hanyang; YU Yiqi; CHENG Xu; LIU Xiaojing

    2008-01-01

    Investigations on the thermal-hydraulic behavior in the SCWR fuel assembly have obtained a significant attention in the international SCWR community. However, there is still a lack of understanding of the heat transfer behavior of supercritical fluids. In this paper, the numerical analysis is carried out to study the thermal-hydraulic behaviour in vertical sub-channels cooled by supercritical water. Remarkable differences in characteristics of secondary flow are found, especially in square lattice, between the upward flow and downward flow. The turbulence mixing across sub-channel gap for downward flow is much stronger than that for upward flow in wide lattice when the bulk temperature is lower than pseudo-critical point temperature. For downward flow, heat transfer deterioration phenomenon is suppressed with respect to the case of upward flow at the same conditions.

  11. Supercritical Assisted Atomization: Polyvinylpyrrolidone as Carrier for Drugs with Poor Solubility in Water

    Directory of Open Access Journals (Sweden)

    Sara Liparoti

    2013-01-01

    Full Text Available Supercritical assisted atomization (SAA is an efficient technique to produce microparticles and composite microspheres formed by polymers and pharmaceutical compounds. In this work polyvinylpyrrolidone (PVP was proposed as carrier for pharmaceutical compounds that show a poor solubility in water medium. Indeed, this polymer is hydrosoluble and can be generally used to enhance the dissolution rate of hydrophobic compounds when finely dispersed in it. However, it is difficult to obtain coprecipitates with a uniform dispersion of the active molecule using other micronization techniques. The experiments were performed using ethanol as solvent; SAA plant was operated at 40°C and 76 bar in the saturator and 70°C and 1.6 bar in the precipitator. Three different dexamethasone/polymer weight ratios were selected: 1/2, 1/4, and 1/8. Produced composite particles showed a regular, spherical shape and a mean diameter ranging from about 0.8 to 1 μm, depending on the polymer/drug weight ratio. Dissolution analysis demonstrated that microparticles containing a lower drug amount show a higher dissolution rate.

  12. Experimental study of the supercritical water oxidation of recalcitrant compounds under hydrothermal flames using tubular reactors.

    Science.gov (United States)

    Cabeza, Pablo; Bermejo, M Dolores; Jiménez, Cristina; Cocero, M José

    2011-04-01

    The hydrothermal flame is a new method of combustion that takes place in supercritical water oxidation reactions when the temperature is higher than the autoignition temperature. In these conditions, waste can be completely mineralized in residence times of milliseconds without the formation of by-products typical of conventional combustion. The object of this work is to study the hydrothermal flame formation in aqueous streams with high concentrations of recalcitrant compounds: an industrial waste with a high concentration of acetic acid and various concentrated solutions of ammonia. A tubular reactor with a residence time of 0.7 s was used. Oxygen was used as the oxidant and isopropyl alcohol (IPA) as co-fuel to reach the operation temperature required. The increase of IPA concentrations in the feeds resulted in a better TOC removal. For mixtures containing acetic acid, 99% elimination of TOC was achieved at temperatures higher than 750 °C. In the case of mixtures containing ammonia, TOC removals reached 99% while maximum total nitrogen removals were never higher than 94%, even for reaction temperatures higher than 710 °C. Ignition was observed at concentrations as high as 6% wt NH(3) with 2% wt IPA while at IPA concentrations below 2% wt IPA, the ammonia did not ignite.

  13. Supercritical water oxidation of colored smoke, dye, and pyrotechnic compositions. Final report: Pilot plant conceptual design

    Energy Technology Data Exchange (ETDEWEB)

    LaJeunesse, C.A.; Chan, Jennifer P.; Raber, T.N.; Macmillan, D.C.; Rice, S.F.; Tschritter, K.L.

    1993-11-01

    The existing demilitarization stockpile contains large quantities of colored smoke, spotting dye, and pyrotechnic munitions. For many years, these munitions have been stored in magazines at locations within the continental United States awaiting completion of the life-cycle. The open air burning of these munitions has been shown to produce toxic gases that are detrimental to human health and harmful to the environment. Prior efforts to incinerate these compositions have also produced toxic emissions and have been unsuccessful. Supercritical water oxidation (SCWO) is a rapidly developing hazardous waste treatment method that can be an alternative to incineration for many types of wastes. The primary advantage SCWO affords for the treatment of this selected set of obsolete munitions is that toxic gas and particulate emissions will not occur as part of the effluent stream. Sandia is currently designing a SCWO reactor for the US Army Armament Research, Development & Engineering Center (ARDEC) to destroy colored smoke, spotting dye, and pyrotechnic munitions. This report summarizes the design status of the ARDEC reactor. Process and equipment operation parameters, process flow equations or mass balances, and utility requirements for six wastes of interest are developed in this report. Two conceptual designs are also developed with all process and instrumentation detailed.

  14. Recovery of phosphorus from sewage sludge in combination with the supercritical water process.

    Science.gov (United States)

    Zhai, Yunbo; Xiang, Bobin; Chen, Hongmei; Xu, Bibo; Zhu, Lu; Li, Caiting; Zeng, Guangming

    2014-01-01

    In this paper, the fraction transformation and recovering of phosphorus (P) from sewage sludge (SS) residues, derived from supercritical water process, was investigated by extraction and precipitation processes. In addition, the form of heavy metals existing during the recovery process is also discussed. First, P in the solid residues was recovered by acid leaching with HCl, and then the derived P was adsorbed by activated alumina (Al(2)O(3)). Finally, the Al2O3 was desorbed with low concentration of NaOH. Results showed that 80% organic P was converted into HCl-P. The total P (the chief ingredient of HCl-P) in solid residue increased from 86.1 to 95.6% as temperature increased from 350 to 400 °C. The amount of P in the solid residue that was dissolved by 1 M HCl was 97.8%, and over 95% of P in the leaching solution (15 mg/L for P concentration) was adsorbed after 5.0 g of Al(2)O(3) powder was added. The amount of P desorbed from Al(2)O(3) with 0.1 M NaOH was 98.7%. Ultimately, over 85% of TP in SS was recovered. Moreover, the proportion of Cu, Zn and Pb in the extracted P products was lower than 5%.

  15. Reactions of supercritical water with benzaldehyde, benzylidenebenzylamine, benzyl alcohol and benzoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Tsao, C.C.; Zhou, Y.; Liu, X.; Houser, T.J. (Western Michigan University, Kalamazoo, MI (USA). Dept. of Chemistry)

    1992-06-01

    This paper describes the results of reaction of benzaldehyde, benzyl alcohol, benzoic acid, and benzylidenebenzylamine with supercritical water (SW) since these compounds were determined or assumed to be major intermediates in the reaction of benzylamine with SW. Supplementary information was obtained from the benzyl benzoate-SW reaction. The kinetics of the benzaldehyde-SW reaction were found to be complex, second-order in benzaldehyde, and inhibited by product(s). The Arrhenius parameters for the second-order rate constant are an activation energy of 179 kJ mol[sup -1] and preexponential factor of 1.6 x 10 (10) M[sup -1]s[sup -1]. In addition, the influences of ammonia and dihydroanthracene on some of the product distributions and extents of reaction were determined. Of particular interest is the reaction pathway leading to the formation of benzene and related products which requires an oxidation/hydrolysis sequence, terminated by decarboxylation to form hydrocarbons. The mechanistic significance of the benzene/tpluene product-yield ratios is discussed.

  16. Capillary pressure heterogeneity and hysteresis for the supercritical CO2/water system in a sandstone

    Science.gov (United States)

    Pini, Ronny; Benson, Sally M.

    2017-10-01

    We report results from an experimental investigation on the hysteretic behaviour of the capillary pressure curve for the supercritical CO2-water system in a Berea Sandstone core. Previous observations have highlighted the importance of subcore-scale capillary heterogeneity in developing local saturations during drainage; we show in this study that the same is true for the imbibition process. Spatially distributed drainage and imbibition scanning curves were obtained for mm-scale subsets of the rock sample non-invasively using X-ray CT imagery. Core- and subcore-scale measurements are well described using the Brooks-Corey formalism, which uses a linear trapping model to compute mobile saturations during imbibition. Capillary scaling yields two separate universal drainage and imbibition curves that are representative of the full subcore-scale data set. This enables accurate parameterisation of rock properties at the subcore-scale in terms of capillary scaling factors and permeability, which in turn serve as effective indicators of heterogeneity at the same scale even when hysteresis is a factor. As such, the proposed core-analysis workflow is quite general and provides the required information to populate numerical models that can be used to extend core-flooding experiments to conditions prevalent in the subsurface, which would be otherwise not attainable in the laboratory.

  17. Supercritical water oxidation of quinazoline: Reaction kinetics and modeling.

    Science.gov (United States)

    Gong, Yanmeng; Guo, Yang; Wang, Shuzhong; Song, Wenhan; Xu, Donghai

    2017-03-01

    This paper presents a first quantitative kinetic model for supercritical water oxidation (SCWO) of quinazoline that describes the formation and interconversion of intermediates and final products at 673-873 K. The set of 11 reaction pathways for phenol, pyrimidine, naphthalene, NH3, etc, involved in the simplified reaction network proved sufficient for fitting the experimental results satisfactorily. We validated the model prediction ability on CO2 yields at initial quinazoline loading not used in the parameter estimation. Reaction rate analysis and sensitivity analysis indicate that nearly all reactions reach their thermodynamic equilibrium within 300 s. The pyrimidine yielding from quinazoline is the dominant ring-opening pathway and provides a significant contribution to CO2 formation. Low sensitivity of NH3 decomposition rate to concentration confirms its refractory nature in SCWO. Nitrogen content in liquid products decreases whereas that in gaseous phase increases as reaction time prolonged. The nitrogen predicted by the model in gaseous phase combined with the experimental nitrogen in liquid products gives an accurate nitrogen balance of conversion process.

  18. Supercritical water gasification of biomass for H2 production: process design.

    Science.gov (United States)

    Fiori, Luca; Valbusa, Michele; Castello, Daniele

    2012-10-01

    The supercritical water gasification (SCWG) of biomass for H(2) production is analyzed in terms of process development and energetic self-sustainability. The conceptual design of a plant is proposed and the SCWG process involving several substrates (glycerol, microalgae, sewage sludge, grape marc, phenol) is simulated by means of AspenPlus™. The influence of various parameters - biomass concentration and typology, reaction pressure and temperature - is analyzed. The process accounts for the possibility of exploiting the mechanical energy of compressed syngas (later burned to sustain the SCWG reaction) through expansion in turbines, while purified H(2) is fed to fuel cells. Results show that the SCWG reaction can be energetically self-sustained if minimum feed biomass concentrations of 15-25% are adopted. Interestingly, the H(2) yields are found to be maximal at similar feed concentrations. Finally, an energy balance is performed showing that the whole process could provide a net power of about 150 kW(e)/(1000 kg(feed)/h).

  19. ABRUPT DEFLECTED SUPERCRITICAL WATER FLOW-REVISED THEORY OF SHOCK WAVE

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The shock wave angle and depth ratio of the abrupt deflected supercritical water flow due to deflector was investigated experimentally and theoretically. A correction coefficient of the hydro-dynamic pressure ξ was introduced to generalize the momentum equation in the perpendicular direction to the shock front. An extensive series of tests were conducted in a 1 m wide flume with the Froude number ranging from 1.70 to 8.37, the deflection angle ranging from 5° to 40° and the length of deflector ranging from 0.28 m to 1 m. A dimensionless parameter K was defined to depict the ratio of the flow height to flow thickness. Test results show that the value of ξ, the correction coefficient of the non-hydrostatic pressure distribution, decreases with the increase of the value of K. An empirical relationship between the value of ξ and the value of K was proposed. It is indicated that the relative errors of the results calculated by the revised theory is much smaller than that obtained from the Ippen theory. Finally, a simple explicit expression was suggested to calculate the shock wave height ratio in consideration of the effect of the non-hydrostatic pressure distribution.

  20. Supercritical water gasification of Eucalyptus grandis and related pyrolysis char: Effect of feedstock composition.

    Science.gov (United States)

    Louw, Jeanne; Schwarz, Cara E; Burger, Andries J

    2016-09-01

    Eucalyptus grandis (E. grandis) wood and char products derived from pyrolysis of E. grandis wood, were gasified in supercritical water at 450°C - with and without the use of a homogeneous (K2CO3) and heterogeneous (Ni/Al2O3-SiO2) catalyst. Gas yields and gasification efficiencies were measured experimentally and compared to calculated thermodynamic equilibrium values, specifically considering the effects of the O/C ratio and volatile matter content of the feed material. Thermodynamically, feed material with lower O/C ratios (0.22) typically resulted in higher CH4 yields (30mol/kgfeed,dry) and gasification efficiencies (188%). However, experimentally, feed material with lower O/C ratios and lower volatile matter resulted in the lowest CH4 yields and gasification efficiencies. Furthermore, a linear relationship between the carbon efficiency (CE) and both the volatile matter content and O/C ratio of the feed material was found to hold true in both catalytic and non-catalytic experiments.

  1. Partial oxidation of landfill leachate in supercritical water: Optimization by response surface methodology.

    Science.gov (United States)

    Gong, Yanmeng; Wang, Shuzhong; Xu, Haidong; Guo, Yang; Tang, Xingying

    2015-09-01

    To achieve the maximum H2 yield (GYH2), TOC removal rate (TRE) and carbon recovery rate (CR), response surface methodology was applied to optimize the process parameters for supercritical water partial oxidation (SWPO) of landfill leachate in a batch reactor. Quadratic polynomial models for GYH2, CR and TRE were established with Box-Behnken design. GYH2, CR and TRE reached up to 14.32mmol·gTOC(-1), 82.54% and 94.56% under optimum conditions, respectively. TRE was invariably above 91.87%. In contrast, TC removal rate (TR) only changed from 8.76% to 32.98%. Furthermore, carbonate and bicarbonate were the most abundant carbonaceous substances in product, whereas CO2 and H2 were the most abundant gaseous products. As a product of nitrogen-containing organics, NH3 has an important effect on gas composition. The carbon balance cannot be reached duo to the formation of tar and char. CR increased with the increase of temperature and oxidation coefficient.

  2. Destruction of OPA from munitions demilitarization in supercritical water oxidation: kinetics of total organic carbon disappearance.

    Science.gov (United States)

    Veriansyah, Bambang; Kim, Jae-Duck; Lee, Jong-Chol; Hong, Deasik

    2006-01-01

    The destruction of OPA from munitions demilitarization has been accomplished in supercritical water oxidation (SCWO) with oxygen as oxidant in an isothermal continuous-flow reactor. The experiments were conducted at a temperature of 689-887 K and a fixed pressure of 25 MPa, with a residence time that ranged from 7 s to 14 s. The destruction efficiency was measured by total organic carbon (TOC) conversion. At the reaction condition, the initial TOC concentrations of OPA were varied from 1.41 mmol/L to 19.57 mmol/L and the oxygen concentrations were varied from 15.03 mmol/L to 81.85 mmol/L. Experimental data showed that all the TOC conversions were >80% under the above experimental conditions. The kinetics of TOC disappearance, which is essential for the design, optimization, and control of reliable commercial SCWO reactor was developed by taking into account the dependence of the oxidant and TOC concentration on the reaction rate. A global TOC disappearance rates expression was regressed from the data of 38 experiments, to a 95% confidence level. The resulting activation energy was determined to be 44.01 +/- 1.52 kJ/mol, and the pre-exponential factor was (1.67 +/- 0.45) x 10(2) L(1.14) mmol(-0.14) s(-1). The reaction orders for the TOC and the oxidant were 0.98 +/- 0.01 and 0.16 +/- 0.02, respectively.

  3. Destruction of chemical agent simulants in a supercritical water oxidation bench-scale reactor

    Energy Technology Data Exchange (ETDEWEB)

    Veriansyah, Bambang [Supercritical Fluid Research Laboratory, Clean Technology Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of) and Department of Green Process and System Engineering, University of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)]. E-mail: vaveri@kist.re.kr; Kim, Jae-Duck [Supercritical Fluid Research Laboratory, Clean Technology Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of) and Department of Green Process and System Engineering, University of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)]. E-mail: jdkim@kist.re.kr; Lee, Jong-Chol [Agency for Defense Development (ADD), P.O. Box 35-1, Yuseong-gu, Daejeon (Korea, Republic of)]. E-mail: jcleeadd@hanafos.com

    2007-08-17

    A new design of supercritical water oxidation (SCWO) bench-scale reactor has been developed to handle high-risk wastes resulting from munitions demilitarization. The reactor consists of a concentric vertical double wall in which SCWO reaction takes place inside an inner tube (titanium grade 2, non-porous) whereas pressure resistance is ensured by a Hastelloy C-276 external vessel. The performances of this reactor were investigated with two different kinds of chemical warfare agent simulants: OPA (a mixture of isopropyl amine and isopropyl alcohol) as the binary precursor for nerve agent of sarin and thiodiglycol [TDG (HOC{sub 2}H{sub 4}){sub 2}S] as the model organic sulfur heteroatom. High destruction rates based on total organic carbon (TOC) were achieved (>99.99%) without production of chars or undesired gases such as carbon monoxide and methane. The carbon-containing product was carbon dioxide whereas the nitrogen-containing products were nitrogen and nitrous oxide. Sulfur was totally recovered in the aqueous effluent as sulfuric acid. No corrosion was noticed in the reactor after a cumulative operation time of more than 250 h. The titanium tube shielded successfully the pressure vessel from corrosion.

  4. Destruction of chemical agent simulants in a supercritical water oxidation bench-scale reactor.

    Science.gov (United States)

    Veriansyah, Bambang; Kim, Jae-Duck; Lee, Jong-Chol

    2007-08-17

    A new design of supercritical water oxidation (SCWO) bench-scale reactor has been developed to handle high-risk wastes resulting from munitions demilitarization. The reactor consists of a concentric vertical double wall in which SCWO reaction takes place inside an inner tube (titanium grade 2, non-porous) whereas pressure resistance is ensured by a Hastelloy C-276 external vessel. The performances of this reactor were investigated with two different kinds of chemical warfare agent simulants: OPA (a mixture of isopropyl amine and isopropyl alcohol) as the binary precursor for nerve agent of sarin and thiodiglycol [TDG, (HOC(2)H(4))2S] as the model organic sulfur heteroatom. High destruction rates based on total organic carbon (TOC) were achieved (>99.99%) without production of chars or undesired gases such as carbon monoxide and methane. The carbon-containing product was carbon dioxide whereas the nitrogen-containing products were nitrogen and nitrous oxide. Sulfur was totally recovered in the aqueous effluent as sulfuric acid. No corrosion was noticed in the reactor after a cumulative operation time of more than 250 h. The titanium tube shielded successfully the pressure vessel from corrosion.

  5. A process for generating power from the oxidation of coal in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    M.D. Bermejo; M.J. Cocero; F. Fernandez-Polanco [Universidad de Valladolid, Valladolid (Spain). Departamento de Ingenieria Quimica

    2004-01-01

    A theoretical study of power generation from oxidation of coal by supercritical water oxidation (SCWO) is presented. Two versions of SCWO power plant are compared to two of the most efficient conventional power plant processes: pulverised coal power plants and pressurised fluidised bed power plant. The effects of steam pressure and temperature on produced (W{sub p}), consumed (W{sub c}) and net work (W{sub N}) are calculated in order to compare the efficiency of these power plants for the same steam conditions. Enthalpies have been calculated using residual enthalpies by Peng Robinson equation of state. Calculated results show that net work in SCWO power plant is 5% higher than in other power plants, due to the fact that no air surplus is necessary for complete combustion and because steam is produced by direct heating. Energetic efficiency of SCWO increases more quickly with temperature than for the other power plants. The effect of steam pressure is different: until 30 MPa power plant efficiencies increase more quickly in SCWO power plants than in conventional plants, but when steam pressures increases beyond 30 MPa, efficiencies decrease in SCWO power plants. 21 refs., 12 figs., 7 tabs.

  6. Energy recovery from secondary pulp/paper-mill sludge and sewage sludge with supercritical water treatment.

    Science.gov (United States)

    Zhang, Linghong; Xu, Chunbao Charles; Champagne, Pascale

    2010-04-01

    Secondary pulp/paper-mill sludge (SPP) and sewage sludges (primary, secondary, and digested sewage sludges) were treated in supercritical water at temperatures ranging between 400 degrees Celsius and 550 degrees Celsius over 20-120 min for energy recovery. Low temperature and short reaction time favored the formation of heavy oil (HO) products, which were mainly composed of a variety of phenol and phenolic compounds, as well as some nitrogen-containing compounds, long-chain alkenes and alcohols, etc., with high gross calorific values (>36 MJ/kg). By contrast, the formation of synthetic gases, a mixture of hydrogen, carbon monoxide, carbon dioxide, methane, and other light hydrocarbons, were not significantly affected by reaction time but greatly enhanced with increasing temperature. The highest gas yield was obtained at 550 degrees Celsius, where 37.7 wt.% of the SPP (on dry basis) was converted into gases, with hydrogen yields as high as 14.5 mol H(2)/kg SPP (on a dry basis). In comparison to sewage sludges, SPP exhibited a greater capability for the production of HO and gases owing to its higher contents of volatiles and alkali metals, indicating a prospective utilization potential for SPP as a source of bio-energy.

  7. Destruction of methylphosphonic acid in a supercritical water oxidation bench-scale double wall reactor

    Institute of Scientific and Technical Information of China (English)

    Bambang Veriansyah; Eun-Seok Song; Jae-Duck Kim

    2011-01-01

    The destruction of methylphosphonic acid (MPA), a final product by hydrolysis/neutralization of organophosphorus agents such as satin and VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothionate), was investigated in a a bench-scale, continuous concentric vertical double wall reactor under supercritical water oxidation condition. The experiments were conducted at a temperature range of 450-600~C and a fixed pressure of 25 MPa. Hydrogen peroxide was used as an oxidant. The destruction efficiency (DE) was monitored by analyzing total organic carbon (TOC) and MPA concentrations using ion chromatography on the liquid effluent samples. The results showed that the DE of MPA up to 99.999% was achieved at a reaction temperature of 600~C, oxygen concentration of 113% storichiometric requirement, and reactor residence time of 8 sec. On the basis of the data derived from experiments, a global kinetic rate equation for the DE of MPA and DE of TOC were developed by nonlinear regression analysis. The model predictions agreed well with the experimental data.

  8. Silicate Carbonation Processes in Water-Bearing Supercritical CO2 Fluids: Implications for Geologic Carbon Sequestration

    Science.gov (United States)

    Miller, Q. R.; Schaef, T.; Thompson, C.; Loring, J. S.; Windisch, C. F.; Bowden, M. E.; Arey, B. W.; McGrail, P.

    2012-12-01

    Global climate change is viewed by many as an anthropogenic phenomenon that could be mitigated through a combination of conservation efforts, alternative energy sources, and the development of technologies capable of reducing carbon dioxide (CO2) emissions. Continued increases of atmospheric CO2 concentrations are projected over the next decade, due to developing nations and growing populations. One economically favorable option for managing CO2 involves subsurface storage in deep basalt formations. The silicate minerals and glassy mesostasis basalt components act as metal cation sources, reacting with the CO2 to form carbonate minerals. Most prior work on mineral reactivity in geologic carbon sequestration settings involves only aqueous dominated reactions. However, in most sequestration scenarios, injected CO2 will reside as a buoyant fluid in contact with the sealing formation (caprock) and slowly become water bearing. Comparatively little laboratory research has been conducted on reactions occurring between minerals in the host rock and the wet scCO2. In this work, we studied the carbonation of wollastonite [CaSiO3] exposed to variably wet supercritical CO2 (scCO2) at a range of temperatures (50, 55 and 70 °C) and pressures (90,120 and 160 bar) in order to gain insight into reaction processes. Mineral transformation reactions were followed by two novel in situ high pressure techniques, including x-ray diffraction that tracked the rate and extents of wollastonite conversion to calcite. Increased dissolved water concentrations in the scCO2 resulted in increased carbonation approaching ~50 wt. %. Development of thin water films on the mineral surface were directly observed with infrared (IR) spectroscopy and indirectly with 18O isotopic labeling techniques (Raman spectroscopy). The thin water films were determined to be critical for facilitating carbonation processes in wet scCO2. Even in extreme low water conditions, the IR technique detected the formation of

  9. Analysis and generalization of experimental data on heat transfer to supercritical pressure water flow in annular channels and rod bundles

    Science.gov (United States)

    Deev, V. I.; Kharitonov, V. S.; Churkin, A. N.

    2017-02-01

    Experimental data on heat transfer to supercritical pressure water presented at ISSCWR-5, 6, and 7 international symposiums—which took place in 2011-2015 in Canada, China, and Finland—and data printed in recent periodical scientific publications were analyzed. Results of experiments with annular channels and three- and four-rod bundles of heating elements positioned in square or triangular grids were examined. Methodology used for round pipes was applied at generalization of experimental data and establishing of correlations suitable for engineering analysis of heat exchange coefficient in conditions of strongly changing water properties in the near-critical pressure region. Empiric formulas describing normal heat transfer to supercritical pressure water mowing in annular channels and rod bundles were obtained. As compared to existing recommendations, suggested correlations are distinguished by specified dependency of heat exchange coefficient on density of heat flux and mass flow velocity of water near pseudo-critical temperature. Differences between computed values of heat exchange coefficient and experimental data usually do not exceed ±25%. Detailed statistical analysis of deviations between computed and experimental results at different states of supercritical pressure water flow was carried out. Peculiarities of deteriorated heat exchange were considered and their existence boundaries were defined. Experimental results obtained for these regimes were generalized using criteria by J.D. Jackson that take the influence of thermal acceleration and Archimedes forces on heat exchange processes into account. Satisfactory agreement between experimental data on heat exchange at flowing of water in annular channels and rod bundles and data for round pipes was shown.

  10. Generation and integration of NaOH into NaCl clusters in supercritical water: a molecular dynamics study on hydrolysis product partitioning.

    Science.gov (United States)

    Nahtigal, Istok G; Svishchev, Igor M

    2009-11-05

    The interaction of water with NaCl nanoparticles at supercritical conditions has been studied by molecular dynamics (MD) simulation. During the nanoparticle nucleation process, water is not only physically adsorbed to the periphery of the NaCl cluster but also exists in a confined state within subsurface regions for several picoseconds. Electrostatic fields generated by the coalescing ions are shown to be on the order of 10(10) V/m, which can drive the hydrolysis of confined water molecules. A molecular mechanism for the sodium chloride hydrolysis reaction at supercritical conditions is suggested. It involves proton transfer from water to chloride ions, followed by hydrolysis product partitioning. We provide MD results displaying the subsurface hydroxide localization in amorphous NaCl clusters, as well as the partitioning of the HCl into the supercritical water phase.

  11. Thermal-hydraulic analysis of heat transfer in subchannels of the European high performance supercritical Water-Cooled Reactor for different CFD turbulence models

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Landy Y.; Rojas, Leorlen Y.; Gamez, Abel; Rosales, Jesus; Gonzalez, Daniel; Garcia, Carlos, E-mail: lcastro@instec.cu, E-mail: leored1984@gmail.com, E-mail: agamezgmf@gmail.com, E-mail: jrosales@instec.cu, E-mail: danielgonro@gmail.com, E-mail: cgh@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Oliveira, Carlos Brayner de, E-mail: cabol@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Dominguez, Dany S., E-mail: dsdominguez@gmail.com [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil). Pos-Graduacao em Modelagem Computacional

    2015-07-01

    Chosen as one of six Generation‒IV nuclear-reactor concepts, Supercritical Water-cooled Reactors (SCWRs) are expected to have high thermal efficiencies within the range of 45 - 50% owing to the reactor's high pressures and outlet temperatures. In this reactor, the primary water enters the core under supercritical-pressure condition (25 MPa) at a temperature of 280 deg C and leaves it at a temperature of up to 510 deg C. Due to the significant changes in the physical properties of water at supercritical-pressure, the system is susceptible to local temperature, density and power oscillations. The behavior of supercritical water into the core of the SCWR, need to be sufficiently studied. Most of the methods available to predict the effects of the heat transfer phenomena within the pseudocritical region are based on empirical one-directional correlations, which do not capture the multidimensional effects and do not provide accurate results in regions such as the deteriorated heat transfer regime. In this paper, computational fluid dynamics (CFD) analysis was carried out to study the thermal-hydraulic behavior of supercritical water flows in sub-channels of a typical European High Performance Light Water Reactor (HPLWR) fuel assembly using commercial CFD code CFX-14. It was determined the steady-state equilibrium parameters and calculated the temperature and density distributions. A comparative study for different turbulence models were carried out and the obtained results are discussed. (author)

  12. Near-infrared spectroscopic study of a water-in-supercritical CO2 microemulsion as a function of the water content.

    Science.gov (United States)

    Takebayashi, Yoshihiro; Sagisaka, Masanobu; Sue, Kiwamu; Yoda, Satoshi; Hakuta, Yukiya; Furuya, Takeshi

    2011-05-19

    A water-in-supercritical CO(2) microemulsion is a reverse micelle encapsulating a nanometer-size water droplet dispersed in supercritical CO(2). In the microemulsion solution, water exists not only in the reverse micelle but also in the solvent CO(2). For quantitative analysis of the water distribution, near-infrared spectra of water + CO(2) and water + surfactant + CO(2) mixtures were measured over a wide range of water/CO(2) ratios from 0.1 to 1.0 wt% at 60 °C and 30.0 MPa. The stretching combination band of water was decomposed into two components, a sharp one peaked at 7194 cm(-1) assigned to monomeric water dissolved in CO(2) and a broad one around 7000 cm(-1) corresponding to aggregated water in the microemulsion. Integrated molar absorptivities of these types of water were negligibly different from each other, despite the different hydrogen-bonding environments. The spectral decomposition revealed that water is distributed mainly into CO(2) at water contents smaller than 0.5 wt% and then is introduced into the microemulsion after saturation of water in CO(2) and full hydration of the surfactant headgroup.

  13. Pourbaix diagrams for the iron-water system extended to high-subcritical and low-supercritical conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cook, William G., E-mail: wcook@unb.ca [Department of Chemical Engineering, University of New Brunswick, P.O. Box 4400, Fredericton, NB, E3B 5A3 (Canada); Olive, Robert P. [Department of Chemical Engineering, University of New Brunswick, P.O. Box 4400, Fredericton, NB, E3B 5A3 (Canada)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Pourbaix diagrams for iron-water are extended to low-supercritical temperatures. Black-Right-Pointing-Pointer Thermodynamic properties for use in R-HKF model re-evaluated. Black-Right-Pointing-Pointer Above the critical point, magnetite solubility is between 10{sup -11} and 10{sup -10} mol/kg. - Abstract: The supercritical water-cooled reactor (SCWR) is a Generation IV reactor concept that will operate at temperatures and pressures above water's thermodynamic critical point. Pourbaix diagrams for the iron-water system at temperatures slightly below and above the critical point at 25 MPa have been constructed to aid the evaluation and development of potential construction materials. High temperature data extrapolation was performed using a revised Helgeson-Kirkham-Flowers model and fit to data on magnetite and hematite solubility in high-temperature water. A low-concentration diagram at 350 Degree-Sign C reveals the importance of water chemistry control to avoid transitioning to an active corrosion region.

  14. Thermal Aspects of Using Alternative Nuclear Fuels in Supercritical Water-Cooled Reactors

    Science.gov (United States)

    Grande, Lisa Christine

    A SuperCritical Water-cooled Nuclear Reactor (SCWR) is a Generation IV concept currently being developed worldwide. Unique to this reactor type is the use of light-water coolant above its critical point. The current research presents a thermal-hydraulic analysis of a single fuel channel within a Pressure Tube (PT)-type SCWR with a single-reheat cycle. Since this reactor is in its early design phase many fuel-channel components are being investigated in various combinations. Analysis inputs are: steam cycle, Axial Heat Flux Profile (AHFP), fuel-bundle geometry, and thermophysical properties of reactor coolant, fuel sheath and fuel. Uniform and non-uniform AHFPs for average channel power were applied to a variety of alternative fuels (mixed oxide, thorium dioxide, uranium dicarbide, uranium nitride and uranium carbide) enclosed in an Inconel-600 43-element bundle. The results depict bulk-fluid, outer-sheath and fuel-centreline temperature profiles together with the Heat Transfer Coefficient (HTC) profiles along the heated length of fuel channel. The objective is to identify the best options in terms of fuel, sheath material and AHFPS in which the outer-sheath and fuel-centreline temperatures will be below the accepted temperature limits of 850°C and 1850°C respectively. The 43-element Inconel-600 fuel bundle is suitable for SCWR use as the sheath-temperature design limit of 850°C was maintained for all analyzed cases at average channel power. Thoria, UC2, UN and UC fuels for all AHFPs are acceptable since the maximum fuel-centreline temperature does not exceed the industry accepted limit of 1850°C. Conversely, the fuel-centreline temperature limit was exceeded for MOX at all AHFPs, and UO2 for both cosine and downstream-skewed cosine AHFPs. Therefore, fuel-bundle modifications are required for UO2 and MOX to be feasible nuclear fuels for SCWRs.

  15. Reaction of water-saturated supercritical CO2 with forsterite: Evidence for magnesite formation at low temperatures

    Science.gov (United States)

    Felmy, Andrew R.; Qafoku, Odeta; Arey, Bruce W.; Hu, Jian Zhi; Hu, Mary; Todd Schaef, H.; Ilton, Eugene S.; Hess, Nancy J.; Pearce, Carolyn I.; Feng, Ju; Rosso, Kevin M.

    2012-08-01

    The nature of the reaction products that form on the surfaces of nanometer-sized forsterite particles during reaction with H2O-saturated supercritical CO2 (scCO2) at 35 °C and 50 °C were examined under in situ conditions and ex situ following reaction. The in situ analysis was conducted by X-ray diffraction (XRD). Ex situ analysis consisted of scanning electron microscopy (SEM) examination of the surface phases and chemical characterization of precipitates using a combination of confocal Raman spectroscopy, 13C and 29Si NMR spectroscopy, and energy-dispersive X-ray spectroscopy (EDS). The results show that the forsterite surface is highly reactive with the primary reaction products being a mixture of nesquehonite (MgCO3·3H2O) and magnesite (MgCO3) at short reaction times (˜3-4 days) and then magnesite (MgCO3) and a highly porous amorphous silica phase at longer reaction times (14 days). After 14 days of reaction most of the original forsterite transformed to reaction products. Importantly, the formation of magnesite was observed at temperatures much lower (35 °C) than previously thought needed to overcome its well-known sluggish precipitation kinetics. The conversion of nesquehonite to magnesite liberates H2O which can potentially facilitate further metal carbonation, as postulated by previous investigators, based upon studies at higher temperature (80 °C). The observation that magnesite can form at lower temperatures implies that water recycling may also be important in determining the rate and extent of mineral carbonation in a wide range of potential CO2 storage reservoirs.

  16. Reaction of Water-Saturated Supercritical CO2 with Forsterite: Evidence for Magnesite Formation at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Felmy, Andrew R.; Qafoku, Odeta; Arey, Bruce W.; Hu, Jian Z.; Hu, Mary Y.; Schaef, Herbert T.; Ilton, Eugene S.; Hess, Nancy J.; Pearce, Carolyn I.; Feng, Ju; Rosso, Kevin M.

    2012-08-01

    The nature of the reaction products that form on the surfaces of nanometer-sized forsterite particles during reaction with H2O saturated supercritical CO2 (scCO2) at 35 C and 50 C were examined under in situ conditions and ex situ following reaction. The in situ analysis was conducted by X-ray diffraction (XRD). Ex situ analysis consisted of scanning electron microscopy (SEM) examination of the surface phases and chemical characterization of precipitates using a combination of confocal Raman spectroscopy, 13C and 29Si NMR spectroscopy, and energy-dispersive X-ray Spectroscopy (EDS). The results show that the forsterite surface is highly reactive with the primary reaction products being a mixture of nesquehonite (MgCO3.3H2O) and magnesite (MgCO3) at short reaction times ({approx}3-4 days) and then magnesite (MgCO3) and a highly porous amorphous silica phase at longer reaction times (14 days). After 14 days of reaction most of the original forsterite transformed to reaction products. Importantly, the formation of magnesite was observed at temperatures much lower (35 C) than previously thought needed to overcome its well known sluggish precipitation kinetics. The conversion of nesquehonite to magnesite liberates H2O which can potentially facilitate further metal carbonation, as postulated by previous investigators, based upon studies at higher temperature (80 C). The observation that magnesite can form at lower temperatures implies that water recycling may also be important in determining the rate and extent of mineral carbonation in a wide range of potential CO2 storage reservoirs.

  17. Effect of heavy hydrogen isotopes on the vibrational line shape for supercritical water through rotational couplings.

    Science.gov (United States)

    Yoshida, Ken; Matubayasi, Nobuyuki; Uosaki, Yasuhiro; Nakahara, Masaru

    2013-04-07

    The rotational couplings, which determine the infrared spectral line shape in the low-density supercritical water, were analyzed as functions of the density and the temperature by applying molecular dynamics simulation to a flexible water model, SPC∕Fw and by varying the moment of inertia of the water through substitution for the H atom in H2O by heavy hydrogen isotopes. The differences in the frequency and the relative intensity between the sharp center peak and the rotational broad side-bands were analyzed for the O-H, O-D, and O-T stretch spectra. The frequency differences between the sharp center peak and the rotational broad side-bands are linearly correlated with the inverse of the moment of inertia of the isotope-substituted water species. The intensity of the sharp peak is associated with the long-time component of the reorientational time correlation function for the stretching bond vector. At 400 °C, where a substantial amount of hydrogen bonds are dynamically persisting, an intensity decrease in the rotational broad side-bands was observed with increasing density from 0.01 to 0.40 g cm(-3), respectively, corresponding to 0.56 and 22.2 M (=mol dm(-3)), orders of magnitude higher than the ideal gas densities. This arises from the decrease in the correlation time of the angular velocity and the rotational couplings due to an increase in the hydrogen-bonding perturbation. The intensity decrease of the rotational side-bands with increasing density is more significant for the water isotopes with heavier hydrogens. At a high temperature of 1200 °C, the rotational side-bands at 0.01 to 0.05 g cm(-3) were more distinct than those at 400 °C, and even at a medium density of 0.40 g cm(-3) a significant signal broadening due to the rotational couplings was clearly observed because of the accelerated rotational momentum. The vibrational spectrum cannot be decomposed into definite chemical clusters for the thermodynamic and kinetic analysis because of the dynamic

  18. Wettability of supercritical carbon dioxide/water/quartz systems: simultaneous measurement of contact angle and interfacial tension at reservoir conditions.

    Science.gov (United States)

    Saraji, Soheil; Goual, Lamia; Piri, Mohammad; Plancher, Henry

    2013-06-11

    Injection of carbon dioxide in deep saline aquifers is considered as a method of carbon sequestration. The efficiency of this process is dependent on the fluid-fluid and rock-fluid interactions inside the porous media. For instance, the final storage capacity and total amount of capillary-trapped CO2 inside an aquifer are affected by the interfacial tension between the fluids and the contact angle between the fluids and the rock mineral surface. A thorough study of these parameters and their variations with temperature and pressure will provide a better understanding of the carbon sequestration process and thus improve predictions of the sequestration efficiency. In this study, the controversial concept of wettability alteration of quartz surfaces in the presence of supercritical carbon dioxide (sc-CO2) was investigated. A novel apparatus for measuring interfacial tension and contact angle at high temperatures and pressures based on Axisymmetric Drop Shape Analysis with no-Apex (ADSA-NA) method was developed and validated with a simple system. Densities, interfacial tensions, and dynamic contact angles of CO2/water/quartz systems were determined for a wide range of pressures and temperatures relevant to geological sequestration of CO2 in the subcritical and supercritical states. Image analysis was performed with ADSA-NA method that allows the determination of both interfacial tensions and contact angles with high accuracy. The results show that supercritical CO2 alters the wettability of quartz surface toward less water-wet conditions compared to subcritical CO2. Also we observed an increase in the water advancing contact angles with increasing temperature indicating less water-wet quartz surfaces at higher temperatures.

  19. Recycling high-performance carbon fiber reinforced polymer composites using sub-critical and supercritical water

    Science.gov (United States)

    Knight, Chase C.

    Carbon fiber reinforced plastics (CFRP) are composite materials that consist of carbon fibers embedded in a polymer matrix, a combination that yields materials with properties exceeding the individual properties of each component. CFRP have several advantages over metals: they offer superior strength to weight ratios and superior resistance to corrosion and chemical attack. These advantages, along with continuing improvement in manufacturing processes, have resulted in rapid growth in the number of CFRP products and applications especially in the aerospace/aviation, wind energy, automotive, and sporting goods industries. Due to theses well-documented benefits and advancements in manufacturing capabilities, CFRP will continue to replace traditional materials of construction throughout several industries. However, some of the same properties that make CFRP outstanding materials also pose a major problem once these materials reach the end of service life. They become difficult to recycle. With composite consumption in North America growing by almost 5 times the rate of the US GDP in 2012, this lack of recyclability is a growing concern. As consumption increases, more waste will inevitably be generated. Current composite recycling technologies include mechanical recycling, thermal processing, and chemical processing. The major challenge of CFRP recycling is the ability to recover materials of high-value and preserve their properties. To this end, the most suitable technology is chemical processing, where the polymer matrix can be broken down and removed from the fiber, with limited damage to the fibers. This can be achieved using high concentration acids, but such a process is undesirable due to the toxicity of such materials. A viable alternative to acid is water in the sub-critical and supercritical region. Under these conditions, the behavior of this abundant and most environmentally friendly solvent resembles that of an organic compound, facilitating the breakdown

  20. 超(近)临界水在有机化学反应中的应用%Application of Supercritical/Near-critical Water in Organic Chemical Reactions

    Institute of Scientific and Technical Information of China (English)

    王炫; 段培高; 戴立益

    2005-01-01

      Supercritical water or near-critical water can serve as an environmentally benign solvent and/or catalyst in chemical reactions. In this paper, several key organic chemical reactions in supercritical and near-critical water in the recent years have been summarized.%  处于临界点及其附近的水可以作为环境友好的溶剂和催化剂应用于化学反应。本文概述了近年来超(近)临界水在重要有机化学反应中的应用。

  1. Solubilization of the poorly water soluble drug, telmisartan, using supercritical anti-solvent (SAS) process.

    Science.gov (United States)

    Park, Junsung; Cho, Wonkyung; Cha, Kwang-Ho; Ahn, Junhyun; Han, Kang; Hwang, Sung-Joo

    2013-01-30

    Telmisartan is a biopharmaceutical classification system (BCS) class II drug that has extremely low water solubility but is freely soluble in highly alkalized solutions. Few organic solvents can dissolve telmisartan. This solubility problem is the main obstacle achieving the desired bioavailability. Because of its unique characteristics, the supercritical anti-solvent (SAS) process was used to BCS class II drug in a variety of ways including micronization, amorphization and solid dispersion. Solid dispersions were prepared using hydroxypropylmethylcellulose/polyvinylpyrrolidone (HPMC/PVP) at 1:0.5, 1:1, and 1:2 weight ratios of drug to polymer, and pure telmisartan was also treated using the SAS process. Processed samples were characterized for morphology, particle size, crystallinity, solubility, dissolution rate and polymorphic stability. After the SAS process, all samples were converted to the amorphous form and were confirmed to be hundreds nm in size. Solubility and dissolution rate were increased compared to the raw material. Solubility tended to increase with increases in the amount of polymer used. However, unlike the solubility results, the dissolution rate decreased with increases in polymer concentration due to gel layer formation of the polymer. Processed pure telmisartan showed the best drug release even though it had lower solubility compared to other solid dispersions; however, because there were no stabilizers in processed pure telmisartan, it recrystallized after 1 month under severe conditions, while the other solid dispersion samples remained amorphous form. We conclude that after controlling the formulation of solid dispersion, the SAS process could be a promising approach for improving the solubility and dissolution rate of telmisartan.

  2. Angle-dependent hard X-ray photoemission study of Nb hydride formation in high-pressure supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Soda, Kazuo, E-mail: j45880a@cc.nagoya-u.ac.jp [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kondo, Hiroki; Yamaguchi, Kanta; Kato, Masahiko [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Shiraki, Tatsuhito; Niwa, Ken; Kusaba, Keiji; Hasegawa, Masashi [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Xeniya, Kozina; Ikenaga, Eiji [Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2015-09-15

    Highlights: • Nb hydrides in 10-GPa supercritical water are studied by photoelectron spectroscopy. • The hydride components of the Nb 3d core-level spectra are increased with the depth. • The bulk valence-band spectrum shows a split band due to the Nb–H bond formation. • The hydrides are formed in the bulk and their surfaces are covered with Nb oxides. - Abstract: Nb hydrides formation in 10-GPa supercritical water has been investigated by angle-dependent micro-beam hard X-ray photoemission spectroscopy. In the Nb 3d core-level spectra, Nb hydride components are found in the slightly high binding energy side of the metallic components, and the oxide ones are observed even though little oxides are recognized in X-ray diffraction patterns. Obtained emission-angle dependence of the Nb 3d core-level spectra of Nb hydride specimens shows that the Nb hydride components increase with the emission angle decreased i.e. the sampling depth increased, while the oxide ones decrease. The bulk valence-band spectrum is obtained by decomposing the measured valence-band spectra into a bulk and surface components with use of the emission-angle dependence of the core-level and valence-band spectra; it consists of two bands. This implies the Nb–H chemical bond formation and Nb in an oxidation state, consistent with reported band structure calculations and the observed core-level chemical shifts. Thus it is confirmed by valence-band and core-level photoelectron spectroscopy that the Nb hydrides are formed inside the specimen, irrespective to the well-known high oxidation ability of supercritical water.

  3. Coupled 3D neutron kinetics and thermalhydraulic characteristics of the Canadian supercritical water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hummel, David William, E-mail: hummeld@mcmaster.ca; Novog, David Raymond

    2016-03-15

    Highlights: • A coupled spatial kinetics and thermalhydraulics model of the PT-SCWR was created. • Positive power excursions were demonstrated during accident-like transients. • The reactor will inherently self-shutdown in such transients with some delay. • A fast-acting shutdown system would limit the consequences of the power pulse. - Abstract: The Canadian Supercritical Water-cooled Reactor concept, as an evolution of the CANada Deuterium Uranium (CANDU) reactor, includes both pressure tubes and a low temperature heavy water moderator. The current Pressure Tube type SCWR (PT-SCWR) concept features 64-element fuel assemblies placed within High Efficiency Re-entrant Channels (HERCs) that connect to core inlet and outlet plena. Among current SCWR concepts the PT-SCWR is unique in that the HERC separates multiple coolant and moderator regions, giving rise to coupled neutronic-thermalhydraulic feedbacks beyond those present in CANDU or contemporary Light Water Reactors. The objective of this work was thus to model the coupled neutronic-thermal hydraulic properties of the PT-SCWR to establish the impact of these multiple regions on the core's transient behavior. To that end, the features of the PT-SCWR were first modeled with the neutron transport code DRAGON to create a database of homogenized and condensed cross-sections and thermalhydraulic feedback coefficients. These were used as input to a core-level neutron diffusion model created with the code DONJON. The behavior of the primary heat transport system was modeled with the thermalhydraulic system code CATHENA. A procedure was developed to couple the outputs of DONJON and CATHENA, facilitating three-dimensional spatial neutron kinetics and coupled thermalhydraulic analysis of the PT-SCWR core. Several postulated transients were initiated within the coupled model by changing the core inlet and outlet boundary conditions. Decreasing coolant density around the fuel was demonstrated to produce positive

  4. The recent development of fabrication of ODS ferritic steels for supercritical water-cooled reactors core application

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Z.; Li, M.; Liao, L.; Liu, X.; He, P.; Xu, Y.; Chen, W.; Ge, C. [Univ. of Science and Technology Beijing, School of Materials Science and Engineering, Beijing (China)

    2010-07-01

    Development of cladding materials which can work at high temperature is crucial to realize highly efficient and high-burnup operation of Generation IV nuclear energy systems. Oxide dispersion strengthened (ODS) ferritic steel is one of the most promising cladding materials for advanced nuclear reactors, such as supercritical water-cooled reactor. ODS ferritic steels with Cr content of 12, 14 and 18% were designed and fabricated in China through the mechanical alloying (MA) route. The process parameters were discussed and optimized. Mechanical properties were measured at room temperature and high temperature. (author)

  5. SUPERCRITICAL WATER PARTIAL OXIDATION PHASE I - PILOT-SCALE TESTING/FEASIBILTY SUDIES FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    SPRITZER.M; HONG,G

    2005-01-01

    General Atomics (GA) is developing Supercritical Water Partial Oxidation (SWPO) as a means of producing hydrogen from low-grade biomass and other waste feeds. The Phase I Pilot-scale Testing/Feasibility Studies have been successfully completed and the results of that effort are described in this report. The key potential advantage of the SWPO process is the use of partial oxidation in-situ to rapidly heat the gasification medium, resulting in less char formation and improved hydrogen yield. Another major advantage is that the high-pressure, high-density aqueous environment is ideal for reacting and gasifying organics of all types. The high water content of the medium encourages formation of hydrogen and hydrogen-rich products and is especially compatible with high water content feeds such as biomass materials. The high water content of the medium is also effective for gasification of hydrogen-poor materials such as coal. A versatile pilot plant for exploring gasification in supercritical water has been established at GA's facilities in San Diego. The Phase I testing of the SWPO process with wood and ethanol mixtures demonstrated gasification efficiencies of about 90%, comparable to those found in prior laboratory-scale SCW gasification work carried out at the University of Hawaii at Manoa (UHM), as well as other biomass gasification experience with conventional gasifiers. As in the prior work at UHM, a significant amount of the hydrogen found in the gas phase products is derived from the water/steam matrix. The studies at UHM utilized an indirectly heated gasifier with an activated carbon catalyst. In contrast, the GA studies utilized a directly heated gasifier without catalyst, plus a surrogate waste fuel. Attainment of comparable gasification efficiencies without catalysis is an important advancement for the GA process, and opens the way for efficient hydrogen production from low-value, dirty feed materials. The Phase I results indicate that a practical

  6. Nonthermal inactivation of Escherichia coli K12 in buffered peptone water using a pilot-plant scale supercritical carbon dioxide system with gas-liquid porous metal contractor

    Science.gov (United States)

    This study evaluated the effectiveness of a supercritical carbon dioxide (SCCO2) system, with a gas-liquid CO2 contactor, for reducing Escherichia coli K12 in diluted buffered peptone water. 0.1% (w/v) buffered peptone water inoculated with E. coli K12 was processed using the SCCO2 system at CO2 con...

  7. Lignin depolymerisation in supercritical carbon dioxide/acetone/water fluid for the production of aromatic chemicals

    NARCIS (Netherlands)

    Gosselink, R.J.A.; Teunissen, W.; Dam, van J.E.G.; Jong, de E.; Gellerstedt, G.; Scott, E.L.; Sanders, J.P.M.

    2012-01-01

    Valorisation of lignin plays a key role in further development of lignocellulosic biorefinery processes the production of biofuels and bio-based materials. In the present study, organosolv hardwood and wheat straw lignins were converted in a supercritical fluid consisting of carbon dioxide/acetone/w

  8. A vibrational spectroscopic study of structure evolution of water dissolved in supercritical carbon dioxide under isobaric heating.

    Science.gov (United States)

    Oparin, R; Tassaing, T; Danten, Y; Besnard, M

    2004-06-08

    A combination of Raman scattering spectroscopy and infrared absorption was applied to investigate the structural evolution of water dissolved in supercritical carbon dioxide under isobaric heating (T=40-340 degrees C, P=250 bar). Quantitative analysis of experimental spectra allowed us to determine that at relatively moderate temperatures water dissolved in CO(2)-rich phase exists only under monomeric form (solitary water surrounding by CO(2) molecules), but hydrogen-bonded species, namely, dimers, begin to appear upon heating. At the same time, the ratio of dimers to monomers concentration increases with further temperature increase and at temperatures close to the temperature of total miscibility of the mixture (T=366 degrees C, P=250 bar), water dimers only are present in the CO(2)-rich phase. (c) 2004 American Institute of Physics.

  9. Experimental study of heat transfer of ultra-supercritical pressure water in vertical upward internally ribbed tube

    Institute of Scientific and Technical Information of China (English)

    Wang Weishu; Chen Tingkuan; Luo Yushan; Gu Hongfang; Yin Fei

    2007-01-01

    Under ultra-supercritical pressure, the heat transfer characteristics of water in vertical upward 4-head internally ribbed tubes with a diameter of 28.65mm and thickness of 8mm were experimentally studied.The experiments were performed at P=25~34MPa,G=450~1800kg/(m2·s)and q=200~600kW/m2. The results show that the pressure has only a moderate effect on the heat transfer of ultra-supercritical water when the water temperature is below the pseudocritical point. Sharp rise of the wall temperature near the pesudocritical region occurs earlier at a higher pressure. Increasing the mass velocity improves the heat transfer with a much stronger effect below the pesudocritical point than that above the pesudocritical point. For given pressure and mass velocity, the inner wall heat flux also shows a significant effect on the inner wall temperature, with a higher inner wall heat flux leading to a higher inner wall temperature. Increasing of inner wall heat flux leads to an early occurrence of sharp rise of the wall temperature. Correlations of heat transfer coefficients are also presented for vertical upward internally ribbed tubes.

  10. Enhanced removal of sodium salts supported by in-situ catalyst synthesis in a supercritical water oxidation process.

    Science.gov (United States)

    Takahashi, F; Sun, Z R; Fukushi, K; Oshima, Y; Yamamoto, K

    2012-01-01

    For practical applications of supercritical water oxidation to wastewater treatment, the deposition of inorganic salts in supercritical phase must be controlled to prevent a reactor from clogging. This study investigated enhanced removal of sodium salts with titanium particles, serving as a salt trapper and a catalyst precursor, and sodium recovery by sub-critical water. When Na(2)CO(3) was tested as a model salt, sodium removal efficiency was higher than theoretically maximum efficiency defined by Na(2)CO(3) solubility. The enhanced sodium removal resulted from in-situ synthesis of sodium titanate, which could catalyse acetic acid oxidation. The kinetics of sodium removal was described well by a diffusion mass-transfer model combined with a power law-type rate model of sodium titanate synthesis. Titanium particles showed positive effect on sodium removal in the case of NaOH, Na(2)SO(4) and Na(3)PO(4). However, they had negligible effect for NaCl and negative effect for Na(2)CrO(4), respectively. More than 99% of trapped sodium was recovered by sub-critical water except for Na(2)CrO(4). In contrast, sodium recovery efficiency remained less than 50% in the case of Na(2)CrO(4). Reused titanium particles showed the same performance for enhanced sodium removal. Enhanced salt removal supported by in-situ catalyst synthesis has great potential to enable both salt removal control and catalytic oxidation.

  11. Corrosion of ferritic-martensitic steels and nickel-based alloys in supercritical water

    Science.gov (United States)

    Ren, Xiaowei

    The corrosion behavior of ferritic/martensitic (F/M) steels and Ni-based alloys in supercritical water (SCW) has been studied due to their potential applications in future nuclear reactor systems, fossil fuel power plants and waste treatment processes. 9˜12% chromium ferritic/martensitic steels exhibit good radiation resistance and stress corrosion cracking resistance. Ni-based alloys with an austenitic face-centered cubic (FCC) structure are designed to retain good mechanical strength and corrosion/oxidation resistance at elevated temperatures. Corrosion tests were carried out at three temperatures, 360°C, 500°C and 600°C, with two dissolved oxygen contents, 25 ppb and 2 ppm for up to 3000 hours. Alloys modified by grain refinement and reactive element addition were also investigated to determine their ability to improve the corrosion resistance in SCW. A duplex oxide structure was observed in the F/M steels after exposure to 25 ppb oxygen SCW, including an outer oxide layer with columnar magnetite grains and an inner oxide layer constituted of a mixture of spinel and ferrite phases in an equiaxed grain structure. An additional outermost hematite layer formed in the SCW-exposed samples when the oxygen content was increased to 2 ppm. Weight gain in the F/M steels increased with exposure temperatures and times, and followed parabolic growth kinetics in most of the samples. In Ni-based alloys after exposure to SCW, general corrosion and pitting corrosion were observed, and intergranular corrosion was found when exposed at 600°C due to formation of a local healing layer. The general oxide structure on the Ni-based alloys was characterized as NiO/Spinel/(CrxFe 1-x)2O3/(Fe,Ni). No change in oxidation mechanism was observed in crossing the critical point despite the large change in water properties. Corrosion resistance of the F/M steels was significantly improved by plasma-based yttrium surface treatment because of restrained outward diffusion of iron by the

  12. Feasibility Study of Supercritical Light Water Cooled Fast Reactors for Actinide Burning and Electric Power Production, 3rd Quarterly Report

    Energy Technology Data Exchange (ETDEWEB)

    Mac Donald, Philip Elsworth

    2002-06-01

    The use of light water at supercritical pressures as the coolant in a nuclear reactor offers the potential for considerable plant simplification and consequent capital and O&M cost reduction compared with current light water reactor (LWR) designs. Also, given the thermodynamic conditions of the coolant at the core outlet (i.e. temperature and pressure beyond the water critical point), very high thermal efficiencies of the power conversion cycle are possible (i.e. up to about 45%). Because no change of phase occurs in the core, the need for steam separators and dryers as well as for BWR-type re-circulation pumps is eliminated, which, for a given reactor power, results in a substantially shorter reactor vessel and smaller containment building than the current BWRs. Furthermore, in a direct cycle the steam generators are not needed.

  13. Pulsed supercritical synthesis of anatase TiO2 nanoparticles in a water-isopropanol mixture studied by in situ powder X-ray diffraction

    Science.gov (United States)

    Eltzholtz, Jakob Rostgaard; Tyrsted, Christoffer; Jensen, Kirsten Marie Ørnsbjerg; Bremholm, Martin; Christensen, Mogens; Becker-Christensen, Jacob; Iversen, Bo Brummerstedt

    2013-02-01

    A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania nanoparticles were synthesized in a 50/50 mixture of water and isopropanol near and above the critical point of water (P = 250 bar, T = 300, 350, 400, 450, 500 and 550 °C). The evolution of the reaction product was followed by sequentially recording PXRD patterns with a time resolution of less than two seconds. The crystallite size of titania is found to depend on both temperature and residence time, and increasing either parameter leads to larger crystallites. A simple adjustment of either temperature or residence time provides a direct method for gram scale production of anatase nanoparticles of average crystallite sizes between 7 and 35 nm, thus giving the option of synthesizing tailor-made nanoparticles. Modeling of the in situ growth curves using an Avrami growth model gave an activation energy of 66(19) kJ mol-1 for the initial crystallization. The in situ PXRD data also provide direct information about the size dependent macrostrain in the nanoparticles and with decreasing crystallite size the unit cell contracts, especially along the c-direction. This agrees well with previous ex situ results obtained for hydrothermal synthesis of titania nanoparticles.A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania

  14. Effect of thermal treatment on the corrosion resistance of Type 316L stainless steel exposed in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Y. [Department of Materials Science & Engineering, McMaster University, Hamilton, ON (Canada); Zheng, W. [CanmetMATERIALS, Natural Resources Canada, Hamilton, ON (Canada); Guzonas, D.A. [Canadian Nuclear Laboratories Chalk River Laboratories, ON (Canada); Cook, W.G. [Department of Chemical Engineering, University of New Brunswick, Fredericton, NB (Canada); Kish, J.R., E-mail: kishjr@mcmaster.ca [Department of Materials Science & Engineering, McMaster University, Hamilton, ON (Canada)

    2015-09-15

    There are still unknown aspects about the growth mechanism of oxide scales formed on candidate stainless steel fuel cladding materials during exposure in supercritical water (SCW) under the conditions relevant to the Canadian supercritical water-cooled reactor (SCWR). The tendency for intermetallic precipitates to form within the grains and on grain boundaries during prolonged exposure at high temperatures represents an unknown factor to corrosion resistance, since they tend to bind alloyed Cr. The objective of this study was to better understand the extent to which intermetallic precipitates affects the mode and extent of corrosion in SCW. Type 316L stainless steel, used as a model Fe–Cr–Ni–Mo alloy, was exposed to 25 MPa SCW at 550 °C for 500 h in a static autoclave for this purpose. Mechanically-abraded samples were tested in the mill-annealed (MA) and a thermally-treated (TT) condition. The thermal treatment was conducted at 815 °C for 1000 h to precipitate the carbide (M{sub 23}C{sub 6}), chi (χ), laves (η) and sigma (σ) phases. It was found that although relatively large intermetallic precipitates formed at the scale/alloy interface locally affected the oxide scale formation, their discontinuous formation did not affect the short-term overall apparent corrosion resistance.

  15. Recycling acetic acid from polarizing film of waste liquid crystal display panels by sub/supercritical water treatments.

    Science.gov (United States)

    Wang, Ruixue; Chen, Ya; Xu, Zhenming

    2015-05-19

    Waste liquid crystal display (LCD) panels mainly contain inorganic materials (glass substrate) and organic materials (polarizing film and liquid crystal). The organic materials should be removed first since containing polarizing film and liquid crystal is to the disadvantage of the indium recycling process. In the present study, an efficient and environmentally friendly process to obtain acetic acid from waste LCD panels by sub/supercritical water treatments is investigated. Furthermore, a well-founded reaction mechanism is proposed. Several highlights of this study are summarized as follows: (i) 99.77% of organic matters are removed, which means the present technology is quite efficient to recycle the organic matters; (ii) a yield of 78.23% acetic acid, a quite important fossil energy based chemical product is obtained, which can reduce the consumption of fossil energy for producing acetic acid; (iii) supercritical water acts as an ideal solvent, a requisite reactant as well as an efficient acid-base catalyst, and this is quite significant in accordance with the "Principles of Green Chemistry". In a word, the organic matters of waste LCD panels are recycled without environmental pollution. Meanwhile, this study provides new opportunities for alternating fossil-based chemical products for sustainable development, converting "waste" into "fossil-based chemicals".

  16. Hydrogen production by supercritical water gasification of biomass. Phase 1 -- Technical and business feasibility study, technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-01

    The nine-month Phase 1 feasibility study was directed toward the application of supercritical water gasification (SCWG) for the economical production and end use of hydrogen from renewable energy sources such as sewage sludge, pulp waste, agricultural wastes, and ultimately the combustible portion of municipal solid waste. Unique in comparison to other gasifier systems, the properties of supercritical water (SCW) are ideal for processing biowastes with high moisture content or contain toxic or hazardous contaminants. During Phase I, an end-to-end SCWG system was evaluated. A range of process options was initially considered for each of the key subsystems. This was followed by tests of sewage sludge feed preparation, pumping and gasification in the SCW pilot plant facility. Based on the initial process review and successful pilot-scale testing, engineering evaluations were performed that defined a baseline system for the production, storage and end use of hydrogen. The results compare favorably with alternative biomass gasifiers currently being developed. The results were then discussed with regional wastewater treatment facility operators to gain their perspective on the proposed commercial SCWG systems and to help define the potential market. Finally, the technical and business plans were developed based on perceived market needs and the projected capital and operating costs of SCWG units. The result is a three-year plan for further development, culminating in a follow-on demonstration test of a 5 MT/day system at a local wastewater treatment plant.

  17. Hydrogen production by supercritical water gasification of biomass. Phase 1 -- Technical and business feasibility study, technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-01

    The nine-month Phase 1 feasibility study was directed toward the application of supercritical water gasification (SCWG) for the economical production and end use of hydrogen from renewable energy sources such as sewage sludge, pulp waste, agricultural wastes, and ultimately the combustible portion of municipal solid waste. Unique in comparison to other gasifier systems, the properties of supercritical water (SCW) are ideal for processing biowastes with high moisture content or contain toxic or hazardous contaminants. During Phase I, an end-to-end SCWG system was evaluated. A range of process options was initially considered for each of the key subsystems. This was followed by tests of sewage sludge feed preparation, pumping and gasification in the SCW pilot plant facility. Based on the initial process review and successful pilot-scale testing, engineering evaluations were performed that defined a baseline system for the production, storage and end use of hydrogen. The results compare favorably with alternative biomass gasifiers currently being developed. The results were then discussed with regional wastewater treatment facility operators to gain their perspective on the proposed commercial SCWG systems and to help define the potential market. Finally, the technical and business plans were developed based on perceived market needs and the projected capital and operating costs of SCWG units. The result is a three-year plan for further development, culminating in a follow-on demonstration test of a 5 MT/day system at a local wastewater treatment plant.

  18. Density dependence of the entropy and the solvation shell structure in supercritical water via molecular dynamics simulation.

    Science.gov (United States)

    Ma, Haibo

    2012-06-07

    We perform molecular dynamics simulations of supercritical water (SCW) with a wide range of densities along a near critical isotherm using the simple point charge extended (SPC/E) pair potential in order to study the entropy and the solvation shell structure around a central water molecule. It is shown that both the translational and orientational two-particle correlation entropy terms can serve as the metrics of the translational-orientational structural orders in water and it is revealed that the translational structural order is very sensitive to the density variation in the gas-like and liquid-like region, while the orientational structural order is much more dependent upon compression in the medium-density SCW region. The comparison of the magnitudes of the full thermodynamic excess entropy and two-particle correlation entropy confirms the recent findings that the many-body terms other than two-body ones also present significant and non-neglectable contributions to the full excess entropy for the highly anomalous fluids like water. The analysis of entropy terms as a function of intermolecular distance and the orientational distribution functions as well as the three-dimensional spatial distribution functions indicate that the structural order occurs only in a much more diffused first solvation shell due to the elongated hydrogen bonds under supercritical conditions. It is revealed that no obvious second or higher neighbor shells occur in SCW, in contrast with the feature of normal liquid water that the anomalous decrease of translational order upon compression occurs mainly in the second shell.

  19. Sensitivity Analysis of Fuel Centerline Temperatures in SuperCritical Water-cooled Reactors (SCWRs)

    Science.gov (United States)

    Abdalla, Ayman

    SuperCritical Water-cooled Reactors (SCWRs) are one of the six nuclear-reactor concepts currently being developed under the Generation-IV International Forum (GIF). A main advantage of SCW Nuclear Power Plants (NPPs) is that they offer higher thermal efficiencies compared to those of current conventional NPPs. Unlike today's conventional NPPs, which have thermal efficiencies between 30 - 35%, SCW NPPs will have thermal efficiencies within a range of 45 - 50%, owing to high operating temperatures and pressures (i.e., coolant temperatures as high as 625°C at 25 MPa pressure). The use of current fuel bundles with UO2 fuel at the high operating parameters of SCWRs may cause high fuel centerline temperatures, which could lead to fuel failure and fission gas release. Studies have shown that when the Variant-20 (43-element) fuel bundle was examined at SCW conditions, the fuel centerline temperature industry limit of 1850°C for UO2 and the sheath temperature design limit of 850°C might be exceeded. Therefore, new fuel-bundle designs, which comply with the design requirements, are required for future use in SCWRs. The main objective of this study to conduct a sensitivity analysis in order to identify the main factors that leads to fuel centerline temperature reduction. Therefore, a 54-element fuel bundle with smaller diameter of fuel elements compared to that of the 43-element bundle was designed and various nuclear fuels are examined for future use in a generic Pressure Tube (PT) SCWR. The 54-element bundle consists of 53 heated fuel elements with an outer diameter of 9.5 mm and one central unheated element of 20-mm outer diameter which contains burnable poison. The 54-element fuel bundle has an outer diameter of 103.45 mm, which is the same as the outer diameter of the 43-element fuel bundle. After developing the 54-element fuel bundle, one-dimensional heat-transfer analysis was conducted using MATLAB and NIST REFPROP programs. As a result, the Heat Transfer

  20. Measuring water adsorption on mineral surfaces in air, CO2, and supercritical CO2 with a quartz-crystal microbalance

    Science.gov (United States)

    Bryan, C. R.; Wells, R. K.; Burton, P. D.; Heath, J. E.; Dewers, T. A.; Wang, Y.

    2011-12-01

    Carbon sequestration via underground storage in geologic formations is a proposed approach for reducing industrial CO2 emissions. However, current models for carbon injection and long-term storage of supercritical CO2 (scCO2) do not consider the development and stability of adsorbed water films at the scCO2-hydrophilic mineral interface. The thickness and properties of the water films control the surface tension and wettability of the mineral surface, and on the core scale, affect rock permeability, saturation, and capillary properties. The film thickness is strongly dependent upon the activity of water in the supercritical fluid, which will change as initially anhydrous scCO2 absorbs water from formation brine. As described in a companion paper by the coauthors, the thickness of the adsorbed water layer is controlled by the disjoining pressure; structural and van der Waals components dominate at low water activity, while electrostatic forces become more important with increasing film thickness (higher water activities). As scCO2 water activity and water layer thickness increase, concomitant changes in mineral surface properties and reservoir/caprock hydrologic properties will affect the mobility of the aqueous phase and of scCO2. Moreover, the development of a water layer may be critical to mineral dissolution reactions in scCO2. Here, we describe the use of a quartz-crystal microbalance (QCM) to monitor adsorption of water by mineral surfaces. QCMs utilize a piezoelectrically-stimulated quartz wafer to measure adsorbed or deposited mass via changes in vibrational frequency. When used to measure the mass of adsorbed liquid films, the frequency response of the crystal must be corrected for the viscoelastic, rather than elastic, response of the adsorbed layer. Results are presented for adsorption to silica in N2 and CO2 at one bar, and in scCO2. Additional data are presented for water uptake by clays deposited on a QCM wafer. In this case, water uptake occurs by the

  1. Development of liquefaction process of coal and biomass in supercritical water; Chorinkaisui wo mochiita sekitan biomass doji ekika process no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nonaka, H.; Matsumura, Y.; Tsutsumi, A.; Yoshida, K. [The University of Tokyo, Tokyo (Japan). Faculty of Engineering; Masuno, Y.; Inaba, A. [National Institute for Resources and Environment, Tsukuba (Japan)

    1996-10-28

    Liquefaction of coal and biomass in supercritical water has been investigated, in which strong solubilization force of supercritical water against hydrocarbons is utilized. Free radicals are formed through the cleavage of covalent bonds in coal under the heating condition at around 400{degree}C during coal liquefaction. It is important to stabilize these unstable intermediate products by hydrogen transfer. On the other hand, hydrogen is not required for the liquefaction of biomass having higher H/C atomic ratio and oxygen content than those of coal. Co-liquefaction of coal and biomass was conducted using supercritical water, in which excess hydrogen from the liquefaction of biomass would be transferred to coal, resulting in the effective liquefaction of coal. Mixture of coal and cellulose was liquefied in supercritical water at 390{degree}C under the pressure of 25 MPa using a semi-continuous reactor, and the results were compared with those from the separate liquefaction of them. The co-liquefaction of coal and cellulose did not show any difference in the residue yield from the separate liquefaction of these, but led to the increased production of compounds with lower molecular weight. The liquefaction was completed in 15 minutes. 5 refs., 3 figs., 3 tabs.

  2. In situ infrared spectroscopic study of brucite carbonation in dry to water-saturated supercritical carbon dioxide.

    Science.gov (United States)

    Loring, John S; Thompson, Christopher J; Zhang, Changyong; Wang, Zheming; Schaef, Herbert T; Rosso, Kevin M

    2012-05-17

    In geologic carbon sequestration, whereas part of the injected carbon dioxide will dissolve into host brine, some will remain as neat to water saturated supercritical CO(2) (scCO(2)) near the well bore and at the caprock, especially in the short term life cycle of the sequestration site. Little is known about the reactivity of minerals with scCO(2) containing variable concentrations of water. In this study, we used high-pressure infrared spectroscopy to examine the carbonation of brucite (Mg(OH)(2)) in situ over a 24 h reaction period with scCO(2) containing water concentrations between 0% and 100% saturation, at temperatures of 35, 50, and 70 °C, and at a pressure of 100 bar. Little or no detectable carbonation was observed when brucite was reacted with neat scCO(2). Higher water concentrations and higher temperatures led to greater brucite carbonation rates and larger extents of conversion to magnesium carbonate products. The only observed carbonation product at 35 °C was nesquehonite (MgCO(3)·3H(2)O). Mixtures of nesquehonite and magnesite (MgCO(3)) were detected at 50 °C, but magnesite was more prevalent with increasing water concentration. Both an amorphous hydrated magnesium carbonate solid and magnesite were detected at 70 °C, but magnesite predominated with increasing water concentration. The identity of the magnesium carbonate products appears strongly linked to magnesium water exchange kinetics through temperature and water availability effects.

  3. Study on the Phase Behavior of Supercritical CO2/Dynol-604/Water System and Solubilization of Methyl Orange in the Microemulsions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    It was found that Dynol-604, a non-fluorous and no silicon-containing nonionic surfactant, was soluble in supercritical (SC) CO2. The phase behavior of SC CO2/Dynol-604/water system was studied. The results showed that one-phase water-in-CO2 microemulsions could be formed. The solubilization of methyl orange in the microemulsions proved further the existence of water domain in the microemulsions.

  4. Study on the Phase Behavior of Supercritical CO2/Dynol—604/Water System and Solubilization of Methyl Orange in the Microemulsions

    Institute of Scientific and Technical Information of China (English)

    JunChengLIU; JianLingZHANG; 等

    2002-01-01

    It was found that Dynol-604, a non-fluorous and no silicon-containing nonionic surfactant,was soluble in supercritical (SC) CO2. The phase behavior of SC CO2/Dynol-604/water system was studies. The results showed that one-phase water-in-CO2 microemulsions could be fromed. The solubilization of methyl orange in the microemulsions proved further the existence of water domain in the microemulsions.

  5. Clay hydration/dehydration in dry to water-saturated supercritical CO2: Implications for caprock integrity

    Energy Technology Data Exchange (ETDEWEB)

    Loring, John S.; Schaef, Herbert T.; Thompson, Christopher J.; Turcu, Romulus VF; Miller, Quin R.; Chen, Jeffrey; Hu, Jian Z.; Hoyt, David W.; Martin, Paul F.; Ilton, Eugene S.; Felmy, Andrew R.; Rosso, Kevin M.

    2013-01-01

    Injection of supercritical CO2 (scCO2) for the geologic storage of carbon dioxide will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water-saturated scCO2. Wet scCO2 is highly reactive and capable of carbonating and hydrating certain minerals, whereas anhydrous scCO2 can dehydrate water-containing minerals. Because these geochemical processes affect solid volume and thus porosity and permeability, they have the potential to affect the long-term integrity of the caprock seal. In this study, we investigate the swelling and shrinkage of an expandable clay found in caprock formations, montmorillonite (Ca-STx-1), when exposed to variable water-content scCO2 at 50 °C and 90 bar using a combination of in situ probes, including X-ray diffraction (XRD), in situ magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), and in situ attenuated total reflection infrared spectroscopy (ATR-IR). We show that the extent of montmorillonite clay swelling/shrinkage is dependent not only on water hydration/dehydration, but also on CO2 intercalation reactions. Our results also suggest a competition between water and CO2 for interlayer residency where increasing concentrations of intercalated water lead to decreasing concentrations of intercalated CO2. Overall, this paper demonstrates the types of measurements required to develop fundamental knowledge that will enhance modeling efforts and reduce risks associated with subsurface storage of CO2.

  6. The structure of the homogeneous oxidation catalyst, Mn(II)(Br(-1))x, in supercritical water: an X-ray absorption fine-structure study.

    Science.gov (United States)

    Chen, Yongsheng; Fulton, John L; Partenheimer, Walter

    2005-10-12

    Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopies were used to probe the first-shell coordination structure about Mn(II) and Br(-1) ions that exist as contact ion pairs in supercritical water. This work was performed to clarify why solutions of MnBr2 in supercritical water are known to effectively catalyze the aerobic oxidative synthesis of terephthalic acid from p-xylene as well as a number of other methylaromatic compounds. The Mn and Br K-edge spectra were collected at the bending magnet beamline (sector 20) at the Advanced Photon Source, Argonne National Laboratory. The first-shell coordination structure about the Mn(II) ion changes from octahedral at ambient conditions to tetrahedral at supercritical conditions. Under supercritical conditions, the measured bond distances of Mn-OH2 and Mn-Br are 2.14 and 2.46 A, respectively. Direct contact ion pairs form with about 2 Br(-1) ions present in the first coordination shell of the Mn(II) ion. The structure of dissolved MnBr2, below 1.0 m, changes from essentially [Mn(II)(H2O)6]+2 to [Mn(II)(H2O)2(Br(-1))2] in supercritical water (scH2O). When an excess of Br(-1) ion is added, the bromide coordination number increases and the number of water molecules decreases. The results show that the initial MnBr2 catalyst in scH2O is tetrahedral with two Mn-Br contact ion pairs. The presence of the acetate anion deactivates the catalyst by formation of insoluble MnO.

  7. The structure of the homogeneous oxidation catalyst, Mn(II)-Br(-I)x, in supercritical water: An x-ray absorption fine structure study

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongsheng; Fulton, John L.; Partenheimer, Walt

    2005-10-12

    Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) spectroscopies were used to probe the first-shell coordination structure of Mn(II) and Br(-I) ion pairs in supercritical water. This work was performed to clarify why solutions of MnBr2 in supercritical water are known to effectively catalyze the aerobic oxidative synthesis of terephthalic acid from p-xylene. The Mn and Br K-edge spectra were collected at the bending magnet beamline (sector 20) at the Advanced Photon Source, Argonne. The first-shell coordination structure about the Mn(II) ion changes from octahedral at ambient conditions to tetrahedral at supercritical conditions. Under supercritical conditions, the measured bond distances of Mn-OH2 and Mn-Br are 2.11 and 2.46 ?, respectively. Direct contact ion pairs form with about 2 Br(-I) ions present in the first coordination shell of the Mn(II) ion. The structure of dissolved MnBr2, below 1.0 m, changes from essentially [Mn(II)(H2O)6]+2 to [Mn(II)(H2O)2(Br)2] in supercritical water (scH2O). When an excess of a Br(-I) ion is added, the bromide coordination increases and the number of water molecules decreases. The results show that the initial MnBr2 catalyst in scH2O is tetrahedral with two Mn-Br contact ion pairs. The presence of the acetate anion deactivates the catalyst by formation of insoluble MnO.

  8. The Structure of the Homogeneous Oxidation Catalyst, Mn(II)(Br[superscript -1])[subscript x], in Supercritical Water: An X-ray Absorption Fine-Structure Study

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongsheng; Fulton, John L.; Partenheimer, Walter (PNNL)

    2008-09-25

    Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopies were used to probe the first-shell coordination structure about Mn(II) and Br{sup -1} ions that exist as contact ion pairs in supercritical water. This work was performed to clarify why solutions of MnBr{sub 2} in supercritical water are known to effectively catalyze the aerobic oxidative synthesis of terephthalic acid from p-xylene as well as a number of other methylaromatic compounds. The Mn and Br K-edge spectra were collected at the bending magnet beamline (sector 20) at the Advanced Photon Source, Argonne National Laboratory. The first-shell coordination structure about the Mn(II) ion changes from octahedral at ambient conditions to tetrahedral at supercritical conditions. Under supercritical conditions, the measured bond distances of Mn-OH{sub 2} and Mn-Br are 2.14 and 2.46 {angstrom}, respectively. Direct contact ion pairs form with about 2 Br{sup -1} ions present in the first coordination shell of the Mn(II) ion. The structure of dissolved MnBr{sub 2}, below 1.0 m, changes from essentially [Mn(II)(H{sub 2}O){sub 6}]{sup +2} to [Mn(II)(H{sub 2}O){sub 2}(Br{sup -1}){sub 2}] in supercritical water (scH{sub 2}O). When an excess of Br{sup -1} ion is added, the bromide coordination number increases and the number of water molecules decreases. The results show that the initial MnBr{sub 2} catalyst in scH{sub 2}O is tetrahedral with two Mn-Br contact ion pairs. The presence of the acetate anion deactivates the catalyst by formation of insoluble MnO.

  9. Mechanisms and kinetics of noncatalytic ether reaction in supercritical water. 2. Proton-transferred fragmentation of dimethyl ether to formaldehyde in competition with hydrolysis.

    Science.gov (United States)

    Nagai, Yasuharu; Matubayasi, Nobuyuki; Nakahara, Masaru

    2005-04-28

    Noncatalytic reaction pathways and rates of dimethyl ether (DME) in supercritical water are determined in a tube reactor made of quartz according to liquid- and gas-phase 1H and 13C NMR observations. The reaction is studied at two concentrations (0.1 and 0.5 M) in supercritical water at 400 degrees C and over a water-density range of 0.1-0.6 g/cm3. The supercritical water reaction is compared with the neat one (in the absence of solvent) at 0.1 M and 400 degrees C. DME is found to decompose through (i) the proton-transferred fragmentation to methane and formaldehyde and (ii) the hydrolysis to methanol. Formaldehyde from reaction (i) is consecutively subjected to four types of redox reactions. Two of them proceed even without solvent: (iii) the unimolecular proton-transferred decarbonylation forming hydrogen and carbon monoxide and (iv) the bimolecular self-disproportionation generating methanol and carbon monoxide. When the solvent water is present, two additional paths are open: (v) the bimolecular self-disproportionation of formaldehyde with reactant water, producing methanol and formic acid, and (vi) the bimolecular cross-disproportionation between formaldehyde and formic acid, yielding methanol and carbonic acid. Methanol is produced through the three types of disproportionations (iv)-(vi) as well as the hydrolysis (ii). The presence of solvent water decelerates the proton-transferred fragmentation of DME; the rate constant is reduced by 40% at 0.5 g/cm3. This is caused by the suppression of low-frequency concerted motion corresponding to the reaction coordinate for the simultaneous C-O bond scission and proton transfer from one methyl carbon to the other. In contrast to the proton-transferred fragmentation, the hydrolysis of DME is markedly accelerated by increasing the water density. The latter becomes more important than the former in supercritical water at densities greater than 0.5 g/cm3.

  10. Effect of property variations on the mixing of turbulent supercritical water streams in a T-junction

    Energy Technology Data Exchange (ETDEWEB)

    Bu, L.; Zhao, J. [Centre for E-City, School of Electrical and Electronics Engineering, Nanyang Technological Univ., Singapore, 639798 (Singapore)

    2012-07-01

    The supercritical water mixing phenomenon is investigated with a wide range of conditions, i.e. the inlet temperature of the streams ranges from 323.15 K to 723.15 K and the pressure ranges from 25 MPa to 45 MPa. A sensitivity study is carried out for the jet and main flow velocity ratio (VR) which is varying from 1 to 40. In addition, the effect of the inject angles of branch flow to main flow on the mixing is conducted by varying the inject angle from 80 deg. to 100 deg.. The results show that the maximum temperature gradient appears on the wall of the upstream side in all the cases, and the inclined angles can be optimized to mitigate the thermal stress. (authors)

  11. The corrosion and stress corrosion cracking behavior of a novel alumina-forming austenitic stainless steel in supercritical water

    Science.gov (United States)

    Sun, Hongying; Yang, Haijie; Wang, Man; Giron-Palomares, Benjamin; Zhou, Zhangjian; Zhang, Lefu; Zhang, Guangming

    2017-02-01

    The general corrosion and stress corrosion behavior of Fe-27Ni-15Cr-5Al-2Mo-0.4Nb alumina-forming austenitic (AFA) steel were investigated in supercritical water under different conditions. A double layer oxide structure was formed: a Fe-rich outer layer (Fe2O3 and Fe3O4) and an Al-Cr-rich inner layer. And the inner layer has a low growth rate with exposing time, which is good for improvement of corrosion resistance. Additionally, some internal nodular Al-Cr-rich oxides were also observed, which resulted in a local absence of inner layer. Stress corrosion specimens exhibited a combination of high strength, good ductility and low susceptibility. The stress strength and elongation was reduced by increasing temperature and amount of dissolved oxygen. In addition, the corresponding susceptibility was increased with decreased temperatures and increased oxygen contents.

  12. Characterizing the effect of creep on stress corrosion cracking of cold worked Alloy 690 in supercritical water environment

    Science.gov (United States)

    Zhang, Lefu; Chen, Kai; Du, Donghai; Gao, Wenhua; Andresen, Peter L.; Guo, Xianglong

    2017-08-01

    The effect of creep on stress corrosion cracking (SCC) was studied by measuring crack growth rates (CGRs) of 30% cold worked (CW) Alloy 690 in supercritical water (SCW) and inert gas environments at temperatures ranging from 450 °C to 550 °C. The SCC crack growth rate under SCW environments can be regarded as the cracking induced by the combined effect of corrosion and creep, while the CGR in inert gas environment can be taken as the portion of creep induced cracking. Results showed that the CW Alloy 690 sustained high susceptibility to intergranular (IG) cracking, and creep played a dominant role in the SCC crack growth behavior, contributing more than 80% of the total crack growth rate at each testing temperature. The temperature dependence of creep induced CGRs follows an Arrhenius dependency, with an apparent activation energy (QE) of about 225 kJ/mol.

  13. Supercritical Fluid Facilitated Growth of Copper and Aluminum Oxide Nanoparticles

    Science.gov (United States)

    Williams, Geoffrey L.; Vohs, Jason K.; Brege, Jonathan J.; Fahlman, Bradley D.

    2005-01-01

    Supercritical fluids (SCFs) possess properties that are intermediate between liquids and gases. The combination of supercritical fluid technology with advanced characterization techniques such as electron microscopy provided a practical and rewarding undergraduate laboratory experiment.

  14. Literature survey of heat transfer and hydraulic resistance of water, carbon dioxide, helium and other fluids at supercritical and near-critical pressures

    Energy Technology Data Exchange (ETDEWEB)

    Pioro, I.L.; Duffey, R.B

    2003-04-01

    This survey consists of 430 references, including 269 Russian publications and 161 Western publications devoted to the problems of heat transfer and hydraulic resistance of a fluid at near-critical and supercritical pressures. The objective of the literature survey is to compile and summarize findings in the area of heat transfer and hydraulic resistance at supercritical pressures for various fluids for the last fifty years published in the open Russian and Western literature. The analysis of the publications showed that the majority of the papers were devoted to the heat transfer of fluids at near-critical and supercritical pressures flowing inside a circular tube. Three major working fluids are involved: water, carbon dioxide, and helium. The main objective of these studies was the development and design of supercritical steam generators for power stations (utilizing water as a working fluid) in the 1950s, 1960s, and 1970s. Carbon dioxide was usually used as the modeling fluid due to lower values of the critical parameters. Helium, and sometimes carbon dioxide, were considered as possible working fluids in some special designs of nuclear reactors. (author)

  15. Effects of salinity and the extent of water on supercritical CO2-induced phlogopite dissolution and secondary mineral formation.

    Science.gov (United States)

    Shao, Hongbo; Ray, Jessica R; Jun, Young-Shin

    2011-02-15

    To ensure the viability of geologic CO2 sequestration (GCS), we need a holistic understanding of reactions at supercritical CO2 (scCO2)-saline water-rock interfaces and the environmental factors affecting these interactions. This research investigated the effects of salinity and the extent of water on the dissolution and surface morphological changes of phlogopite [KMg2.87Si3.07Al1.23O10(F,OH)2], a model clay mineral in potential GCS sites. Salinity enhanced the dissolution of phlogopite and affected the location, shape, size, and phase of secondary minerals. In low salinity solutions, nanoscale particles of secondary minerals formed much faster, and there were more nanoparticles than in high salinity solutions. The effect of water extent was investigated by comparing scCO2-H2O(g)-phlogopite and scCO2-H2O(l)-phlogopite interactions. Experimental results suggested that the presence of a thin water film adsorbed on the phlogopite surface caused the formation of dissolution pits and a surface coating of secondary mineral phases that could change the physical properties of rocks. These results provide new information for understanding reactions at scCO2-saline water-rock interfaces in deep saline aquifers and will help design secure and environmentally sustainable CO2 sequestration projects.

  16. CFD modelling of supercritical water flow and heat transfer in a 2 × 2 fuel rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Podila, Krishna, E-mail: krishna.podila@cnl.ca; Rao, Yanfei, E-mail: yanfei.rao@cnl.ca

    2016-05-15

    Highlights: • Bare and wire wrapped 2 × 2 fuel rod bundles were modelled with CFD. • Sensitivity of predictions to SST k–ω, v{sup 2}–f and turbulent Prandtl number was tested. • CFD predictions were assessed with experimentally reported fuel wall temperatures. - Abstract: In the present assessment of the CFD code, two heat transfer experiments using water at supercritical pressures were selected: a 2 × 2 rod bare bundle; and a 2 × 2 rod wire-wrapped bundle. A systematic 3D CFD study of the fluid flow and heat transfer at supercritical pressures for the rod bundle geometries was performed with the key parameter being the fuel rod wall temperature. The sensitivity of the prediction to the steady RANS turbulence models of SST k–ω, v{sup 2}–f and turbulent Prandtl number (Pr{sub t}) was tested to ensure the reliability of the predicted wall temperature obtained for the current analysis. Using the appropriate turbulence model based on the sensitivity analysis, the mesh refinement, or the grid convergence, was performed for the two geometries. Following the above sensitivity analyses and mesh refinements, the recommended CFD model was then assessed against the measurements from the two experiments. It was found that the CFD model adopted in the current work was able to qualitatively capture the trends reported by the experiments but the degree of temperature rise along the heated length was underpredicted. Moreover, the applicability of turbulence models varied case-by-case and the performance evaluation of the turbulence models was primarily based on its ability to predict the experimentally reported fuel wall temperatures. Of the two turbulence models tested, the SST k–ω was found to be better at capturing the measurements at pseudo-critical and supercritical test conditions, whereas the v{sup 2}–f performed better at sub-critical test conditions. Along with the appropriate turbulence model, CFD results were found to be particularly sensitive to

  17. Drying of supercritical carbon dioxide with membrane processes

    NARCIS (Netherlands)

    Lohaus, Theresa; Scholz, Marco; Koziara, Beata T.; Benes, N.E.; Wessling, Matthias

    2015-01-01

    In supercritical extraction processes regenerating the supercritical fluid represents the main cost constraint. Membrane technology has potential for cost efficient regeneration of water-loaded supercritical carbon dioxide. In this study we have designed membrane-based processes to dehydrate water-l

  18. Effect of impurities on the corrosion behavior of CO2 transmission pipeline steel in supercritical CO2-water environments.

    Science.gov (United States)

    Choi, Yoon-Seok; Nesic, Srdjan; Young, David

    2010-12-01

    The corrosion property of carbon steel was evaluated using an autoclave under CO(2)-saturated water phase and water-saturated CO(2) phase with impurities (O(2) and SO(2)) at 80 bar CO(2) and 50 °C to simulate the condition of CO(2) transmission pipeline in the carbon capture and storage (CCS) applications. The results showed that the corrosion rate of carbon steel in CO(2)-saturated water was very high and it increased with adding O(2) in the system due to the inhibition effect of O(2) on the formation of protective FeCO(3). It is noteworthy that corrosion took place in the water-saturated CO(2) phase under supercritical condition when no free water is present. The addition of O(2) increased the corrosion rates of carbon steel in water-saturated CO(2) phase. The addition of 0.8 bar SO(2) (1%) in the gas phase dramatically increased the corrosion rate of carbon steel from 0.38 to 5.6 mm/y. This then increased to more than 7 mm/y with addition of both O(2) and SO(2). SO(2) can promote the formation of iron sulfite hydrate (FeSO(3)·3H(2)O) on the steel surface which is less protective than iron carbonate (FeCO(3)), and it is further oxidized to become FeSO(4) and FeOOH when O(2) is present with SO(2) in the CO(2)-rich phase. The corrosion rates of 13Cr steel were very low compared with carbon steel in CO(2)-saturated water environments with O(2), whereas it was as high as carbon steel in a water-saturated CO(2) phase with O(2) and SO(2).

  19. Evidence of Scrambling over Ruthenium-based Catalysts in Supercritical-water Gasification

    DEFF Research Database (Denmark)

    Peterson, Andrew A.; Dreher, Marian; Wambach, Jörg

    2012-01-01

    of the 1/4- or 1/2-substituted species CH3D and CH2D2. The experiment was repeated with an in-house impregnated RuO2-on-carbon catalyst, with similar results. Although other criteria such as the ability to cleave C, C and C, O bonds and resistance to poisoning will also prove important, this study suggests...... and the descriptors that would enable the search for other catalysts with high conversions have not been determined. In the current work, we use electronic structure calculations coupled with batch experiments to understand the interaction of methane (CH4) and water (H2O) with a common catalyst material, ruthenium...

  20. Non-Catalytic and MgSO4 - Catalyst based Degradation of Glycerol in Subcritical and Supercritical Water Media

    Directory of Open Access Journals (Sweden)

    Mahfud Mahfud

    2011-02-01

    Full Text Available This research aims to study the glycerol degradation reaction in subcritical and supercritical water media. The degradation of glycerol into other products was performed both with sulphate salt catalysts and without catalyst. The reactant was made from glycerol and water with the mass ratio of 1:10. The experiments were carried out using a batch reactor at a constant pressure of 250 kgf/cm2, with the temperature range of 200-400oC, reaction time of 30 minutes, and catalyst mol ratio in glycerol of 1:10 and 1:8. The products of the non-catalytic glycerol degradation were acetaldehyde, methanol, and ethanol. The use of sulphate salt as catalyst has high selectivity to acetaldehyde and still allows the formation alcohol product in small quantities. The mechanism of ionic reaction and free radical reaction can occur at lower temperature in hydrothermal area or subcritical water. Conversion of glycerol on catalytic reaction showed a higher yield when compared with the reaction performed without catalyst

  1. New Linear Partitioning Models based on Experimental WaterSupercritical CO2 Partitioning Data of Selected Organic Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Burant, Aniela S.; Thompson, Christopher J.; Lowry, Gregory; Karamalidis, Athanasios

    2016-05-17

    Partitioning coefficients of organic compounds between water and supercritical CO2 (sc-CO2) are necessary to assess the risk of migration of these chemicals from subsurface CO2 storage sites. Despite the large number of potential organic contaminants, the current data set of published water-sc-CO2 partitioning coefficients is very limited. Here, the partitioning coefficients of thiophene, pyrrole, and anisole were measured in situ over a range of temperatures and pressures using a novel pressurized batch reactor system with dual spectroscopic detectors: a near infrared spectrometer for measuring the organic analyte in the CO2 phase, and a UV detector for quantifying the analyte in the aqueous phase. Our measured partitioning coefficients followed expected trends based on volatility and aqueous solubility. The partitioning coefficients and literature data were then used to update a published poly-parameter linear free energy relationship and to develop five new linear free energy relationships for predicting water-sc-CO2 partitioning coefficients. Four of the models targeted a single class of organic compounds. Unlike models that utilize Abraham solvation parameters, the new relationships use vapor pressure and aqueous solubility of the organic compound at 25 °C and CO2 density to predict partitioning coefficients over a range of temperature and pressure conditions. The compound class models provide better estimates of partitioning behavior for compounds in that class than the model built for the entire dataset.

  2. Impact of supercritical CO{sub 2}/water interaction on the cap-rock nano-porous structure

    Energy Technology Data Exchange (ETDEWEB)

    Rhenals Garrido, David Ricardo [Institut National de l' Environnement Industriel et des Risques (INERIS), Verneuil-en-Halatte, 60 550 (France); Ecole Nationale d' Ingenieurs de Saint Etienne (ENISE), Saint-Etienne 42 000 (France); Lafortune, Stephane [Institut National de l' Environnement Industriel et des Risques (INERIS), Verneuil-en-Halatte, 60 550 (France); Souli, Hanene; Dubujet, Philippe [Ecole Nationale d' Ingenieurs de Saint Etienne (ENISE), Saint-Etienne 42 000 (France)

    2013-07-01

    In the context of CO{sub 2} geological storage, storage capacity and safety are two aspects to be evaluated in order to ensure the efficiency of this operation. The safety of this technique is primarily related to the conservation of the intrinsic properties of the cap-rock (stratigraphic trapping), which are controlled by the porous structure. This paper focuses on the assessment of the impact caused by the CO{sub 2}/water interaction on the porous nano-structure. A suspension of crushed rock samples and synthetic water was reacted with supercritical CO{sub 2} at 84 bar and 53 deg. C under static conditions over a 2-month period. At the end of the experiment, the solid and liquid phases were collected in order to analyze the porous structure of the rock and water chemistry. Over short time periods, the results show a slight increase of the microporous and meso-porous volumes due to the rapid dissolution of calcite compared to the slower dissolution of aluminosilicates. (authors)

  3. Experimental study on temperature distribution of membrane water wall in an ultra-supercritical pressure once-through boiler burning zhundong coal

    Science.gov (United States)

    He, Honghao; Li, Wenjun; Zeng, Jun; Xie, Guohong; Peng, Min; Duan, Xuenong

    2017-05-01

    Taking an ultra-supercritical pressure once-through boiler as an example, the temperature distribution of the lower membrane water wall is investigated experimentally, the conclusion reveals that increasing the proportion of Zhundong coal can effectively reduce the district heat load, which benefits the temperature uniformity in the lower membrane water wall. When the boiler being operated at middle load, the temperature deviation in lower membrane water wall increase simultaneously, one of the reasons is that the restriction orifice could not adjust the flow rate of working fluid as expected. By adjusting boiler performance, the temperature uniformity of lower membrane water wall can be improved to a certain degree.

  4. Supercritical carbon dioxide-based sterilization of decellularized heart valves.

    Science.gov (United States)

    Hennessy, Ryan S; Jana, Soumen; Tefft, Brandon J; Helder, Meghana R; Young, Melissa D; Hennessy, Rebecca R; Stoyles, Nicholas J; Lerman, Amir

    2017-02-01

    The goal of this research project encompasses finding the most efficient and effective method of decellularized tissue sterilization. Aortic tissue grafts have been utilized to repair damaged or diseased valves. Although, the tissues for grafting are collected aseptically, it does not eradicate the risk of contamination nor disease transfer. Thus, sterilization of grafts is mandatory. Several techniques have been applied to sterilize grafts; however, each technique shows drawbacks. In this study, we compared several sterilization techniques: supercritical carbon dioxide, electrolyzed water, gamma radiation, ethanol-peracetic acid, and hydrogen peroxide for impact on the sterility and mechanical integrity of porcine decellularized aortic valves. Valve sterility was characterized by histology, microbe culture, and electron microscopy. Uniaxial tensile testing was conducted on the valve cusps along their circumferential orientation to study these sterilization techniques on their integrity. Ethanol-peracetic acid and supercritical carbon dioxide treated valves were found to be sterile. The tensile strength of supercritical carbon dioxide treated valves (4.28 ± 0.22 MPa) was higher to those valves treated with electrolyzed water, gamma radiation, ethanol-peracetic acid and hydrogen peroxide (1.02 ± 0.15, 1.25 ± 0.25, 3.53 ± 0.41 and 0.37 ± 0.04 MPa, respectively). Superior sterility and integrity were found in the decellularized porcine aortic valves with supercritical carbon dioxide sterilization. This sterilization technique may hold promise for other decellularized soft tissues. Sterilization of grafts is essential. Supercritical carbon dioxide, electrolyzed water, gamma radiation, ethanol-peracetic acid, and hydrogen peroxide techniques were compared for impact on sterility and mechanical integrity of porcine decellularized aortic valves. Ethanol-peracetic acid and supercritical carbon dioxide treated valves were found to be sterile using histology, microbe

  5. Co-detoxification of transformer oil-contained PCBs and heavy metals in medical waste incinerator fly ash under sub- and supercritical water.

    Science.gov (United States)

    Wang, Chunfeng; Zhu, Nengmin; Wang, Yanmin; Zhang, Fushen

    2012-01-17

    The simultaneous detoxification processes of transformer oil-contained PCBs and heavy metals in medical waste incinerator (MWI) fly ash were developed under sub- and supercritical water. The addition of MWI fly ash to transformer oil-contained PCBs was found to increase the destruction efficiency of PCBs, at the same time, it facilitated reducing the leaching concentration of toxic metals from residues (obtained after reaction) for harmless disposal. In this study, we elucidated primarily the catalysis possibility of heavy metals in raw MWI fly ash for PCBs degradation by adopting the sequential extraction procedure. For both MWI fly ashes, more than 90% destruction efficiency of PCBs was achieved at ≥375 °C for 30 min, and trichlorobenzene (TCB) existing in the transformer oil was also completely decomposed. The correlation of catalytic performance to PCBs degradation was discussed based on structural characteristics and dechlorinated products. Likewise, such process rendered residues innocuous through supercritical water treatment for reuse or disposal in landfill.

  6. The Optimization of the Water Supply System of the 350MW Supercritical Unit%350MW超临界机组给水系统的优化

    Institute of Scientific and Technical Information of China (English)

    欧一顺

    2012-01-01

    Based on the different configuration schemes for the water supply systems of the 350MW supercritical units in the firststage and secondstage projects of Huaneng Dongfang Power Plant, this essay analyzes both their advanta ges and disadvantages in the aspects of cost, security, economy and reliability, to provide reference for the optimiza tion of the water supply system of the 350MW supercritical unit.%结合华能东方电厂一、二期工程350MW超临界机组给水系统的不同配置方案,从造价、安全、经济、可靠性方面分析给水系统不同配置方案的优缺点,为350MW等级超临界机组给水系统的优化提供参考。

  7. Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production, Progress Report for Work Through September 2003, 2nd Annual/8th Quarterly Report

    Energy Technology Data Exchange (ETDEWEB)

    Philip E. MacDonald

    2003-09-01

    The supercritical water-cooled reactor (SCWR) is one of the six reactor technologies selected for research and development under the Generation-IV program. SCWRs are promising advanced nuclear systems because of their high thermal efficiency (i.e., about 45% vs. about 33% efficiency for current Light Water Reactors, LWRs) and considerable plant simplification. SCWRs are basically LWRs operating at higher pressure and temperatures with a direct once-through cycle. Operation above the critical pressure eliminates coolant boiling, so the coolant remains single-phase throughout the system. Thus the need for recirculation and jet pumps, a pressurizer, steam generators, steam separators and dryers is eliminated. The main mission of the SCWR is generation of low-cost electricity. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and supercritical fossil-fired boilers, a large number of which is also in use around the world.

  8. Near-infrared spectroscopic investigation of water in supercritical CO2 and the effect of CaCl2

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zheming; Felmy, Andrew R.; Thompson, Christopher J.; Loring, John S.; Joly, Alan G.; Rosso, Kevin M.; Schaef, Herbert T.; Dixon, David A.

    2013-01-01

    Near-infrared (NIR) spectroscopy was applied to investigate the dissolution and chemical interaction of water dissolved into supercritical carbon dioxide (scCO2) and the influence of CaCl2 in the co-existing aqueous phase at fo empe e : 40 50 75 nd 100 C at 90 atm. Consistent with the trend of the vapor pressure of water, the solubility of pure water in scCO2 inc e ed f om 40 °C (0.32 mole%) o 100 °C (1.61 mole%). The presence of CaCl2 negatively affects the solubility of water in scCO2: at a given temperature and pressure the solubility of water decreased as the concentration of CaCl2 in the aqueous phase increased, following the trend of the activity of water. A 40 °C, the water concentration in scCO2 in contact with saturated CaCl2 aqueous solution was only 0.16 mole%, a drop of more than 50% as compared to pure water while that a 100 °C was 1.12 mole%, a drop of over 30% as compared to pure water, under otherwise the same conditions. Analysis of the spectral profiles suggested that water dissolved into scCO2 exists in the monomeric form under the evaluated temperature and pressure conditions, for both neat water and CaCl2 solutions. However, its rotational degrees of freedom decrease at lower temperatures due to higher fluid densities, leading to formation of weak H2O:CO2 Lewis acid-base complexes. Similarly, the nearly invariant spectral profiles of dissolved water in the presence and absence of saturated CaCl2 under the same experimental conditions was taken as evidence that CaCl2 dissolution in scCO2 was limited as the dissolved Ca2+/CaCl2 would likely be highly hydrated and would alter the overall spectra of waters in the scCO2 phase.

  9. Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.

    Science.gov (United States)

    Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

    2015-01-06

    CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena.

  10. Deoxy-liquefaction of switchgrass in supercritical water with calcium formate as an in-situ hydrogen donor.

    Science.gov (United States)

    Ramsurn, Hema; Gupta, Ram B

    2013-09-01

    Switchgrass was liquefied in supercritical water (SCW) using Ca(HCOO)2 as an in-situ source of hydrogen to enhance deoxygenation and the quality of the biocrude obtained. In SCW, Ca(HCOO)2 produces hydrogen via decomposition and hydrolysis reactions, and simultaneously switchgrass hydrolyzes to form oxygenated hydrocarbon compounds. Because of the close proximity of the newly-formed hydrogen and active hydrocarbons, hydrodeoxygenation occurred whereby some of the oxygenated compounds were upgraded by the removal of oxygen in the form of water. The analysis of the so-formed biocrude revealed the presence of benzene, polyaromatic hydrocarbons, and alkyl phenolics. The benzene formation is attributed to the hydrogenation of phenols but also due to the Diels-Alder alkene addition, followed by dehydrogenation. The addition of Ca(HCOO)2 doubled the yield of biocrude (10 wt%) and increased the heating value from 28 to 34 kJ/g. Formic acid amount increased in the aqueous biocrude due to the enhanced decomposition of xylose and glucose.

  11. Experimental study of crossover from capillary to viscous fingering for supercritical CO2-water displacement in a homogeneous pore network.

    Science.gov (United States)

    Wang, Ying; Zhang, Changyong; Wei, Ning; Oostrom, Mart; Wietsma, Thomas W; Li, Xiaochun; Bonneville, Alain

    2013-01-02

    Carbon sequestration in saline aquifers involves displacing brine from the pore space by supercritical CO(2) (scCO(2)). The displacement process is considered unstable due to the unfavorable viscosity ratio between the invading scCO(2) and the resident brine. The mechanisms that affect scCO(2)-water displacement under reservoir conditions (41 °C, 9 MPa) were investigated in a homogeneous micromodel. A large range of injection rates, expressed as the dimensionless capillary number (Ca), was studied in two sets of experiments: discontinuous-rate injection, where the micromodel was saturated with water before each injection rate was imposed, and continuous-rate injection, where the rate was increased after quasi-steady conditions were reached for a certain rate. For the discontinuous-rate experiments, capillary fingering and viscous fingering are the dominant mechanisms for low (logCa ≤ -6.61) and high injection rates (logCa ≥ -5.21), respectively. Crossover from capillary to viscous fingering was observed for logCa = -5.91 to -5.21, resulting in a large decrease in scCO(2) saturation. The discontinuous-rate experimental results confirmed the decrease in nonwetting fluid saturation during crossover from capillary to viscous fingering predicted by numerical simulations by Lenormand et al. (J. Fluid Mech.1988, 189, 165-187). Capillary fingering was the dominant mechanism for all injection rates in the continuous-rate experiment, resulting in monotonic increase in scCO(2) saturation.

  12. A nanosystem for water-insoluble drugs prepared by a new technology, nanoparticulation using a solid lipid and supercritical fluid.

    Science.gov (United States)

    Park, Joo Won; Yun, Jeong Min; Lee, Eun Seong; Youn, Yu Seok; Kim, Kab Sig; Oh, Young Taik; Oh, Kyung Teak

    2013-11-01

    While the number and diversity of lead compounds has increased with the development of science technologies, ca. 90 % of new chemical entities under development have shown low aqueous solubility, classified as class II or IV of the biopharmaceutics classification system (BCS). The low aqueous solubility hinders their clinical translations due to low bioavailability and dissolution-limited absorption of orally-administered drugs. Several technologies have been employed to improve the solubility of poorly water-soluble drugs. In this paper, a new method of nanoparticulation using fat and a supercritical fluid (NUFS) for the formulation of hydrophobic drugs was applied to solve the low solubility problem. A typical BCS class II drug, itraconazole, was selected and formulated with hydroxypropyl methylcellulose, emulsification, and anticoagulating agents for NUFS. The non-spherical itraconazole nanoparticles prepared by NUFS were ~300-500 nm in size with a ~15-fold improved dissolution rate compared to non-nanoparticles of itraconazole (i.e., raw itraconazole). In addition, a high drug content of ~46 % by weight and a drug loading efficiency greater than 85 % were achieved. Therefore, the new technology for nano-platforms could be a promising solution for solubilization of poorly water-soluble drugs, resulting in improved bioavailability.

  13. Highly methyl-branched hydrocarbon surfactant as a CO₂-philic solubilizer for water/supercritical CO₂ microemulsion.

    Science.gov (United States)

    Sagisaka, Masanobu; Kudo, Kotaro; Nagoya, Shota; Yoshizawa, Atsushi

    2013-01-01

    To develop an efficient and fluorine-free solubilizer for a water/supercritical CO₂ microemulsion (W/CO₂ μE), in this study, a highly methyl-branched alkyl, isostearyl group was focused on as a CO₂-philic tail, and the custom-made isostearyl surfactant, sodium 2-(4,4-dimethylpentan-2-yl)-5,7,7-trimethyloctyl sulfate (SIS1) was synthesized. The surface tension (γ) of an aqueous SIS1 solution was measured at ambient pressure as a function of surfactant concentration, and it was found to be 25 mN/m at concentrations of > 1.5 mM. A low γ value can generally be reached only by a fluorocarbon surfactant, which implies that SIS1 has an excellent solubilizing power for the W/CO₂ μE, similar to some fluorocarbon surfactants reported previously. Visual observations of the SIS1/W/CO₂ mixtures revealed the formation of transparent single phases without separated water, identified as W/CO₂ μE. The μE was well-stabilized at pressures > 210 bar and temperatures > 55 °C. At 75 °C and 370 bar, SIS1 was found by spectral measurements using a water-soluble UV-light absorber to solubilize water contents up to a maximum water-to-surfactant molar ratio (W0) = 50. The achievement of W0 = 50 in a W/CO₂ μE system has not been reported previously in similar hydrocarbon surfactant/W/CO₂ systems, and this demonstrates that a highly methyl-branched alkyl group can act as a good CO₂-philic group for a W/CO₂ -type surfactant.

  14. Heat transfer characteristics of supercritical water in different shape channels%不同通道内超临界水流动换热特性

    Institute of Scientific and Technical Information of China (English)

    宋明强; 周涛; 陈柏旭; 黄彦平; 夏榜样

    2015-01-01

    以具有不同当量直径的矩形、圆形、三角形、环形等管道为研究对象,利用ANSYS CFX分别计算在定质量流量和定流体速度条件下,超临界水在不同通道内的流动换热特性。发现在定质量流量条件下,圆形通道换热特性最优,且小当量直径促进流体换热;在定入口流速条件下,环形通道换热特性最优,小当量直径管道促进亚临界流体换热,大当量直径管道促进超临界流体换热。%Background: Supercritical water reactor (SCWR) is the only one that uses light water as a coolant among all fourth generation nuclear reactors.Purpose: This study aims to investigate the characteristics of supercritical water heat transfer in various pipelines.Methods: The models of rectangular, triangular, circle and annular channels are employed, with equivalent diameters of 2 mm, 3 mm and 5 mm for each of them. Based on these models, heat transfer charactersistics of supercritical water in different shape channels at certain mass flow and fluid velocity were calculatedvia ANSYS CFX.Results: There are two situations for the same equivalent diameter: in the condition of constant mass flow rate, the heat transfer property of circle channel outperforms other three types of channels, and the smaller equivalent diameter channels, the better of the heat transfer. In constant fluid velocity condition, the heat transfer property of annular channel presents best performance over others, and the smaller equivalent diameter channels, the better of the heat transfer in subcritical condition whilst the bigger equivalent diameter channels, the better of the heat transfer in supercritical condition.Conclusion: Compared with the experimental results, the model can provide a certain reference for the design of supercritical water reactor.

  15. Application of supercritical water to decompose brominated epoxy resin and environmental friendly recovery of metals from waste memory module.

    Science.gov (United States)

    Li, Kuo; Xu, Zhenming

    2015-02-03

    Waste Memory Modules (WMMs), a particular kind of waste printed circuit board (WPCB), contain a high amount of brominated epoxy resin (BER), which may bring a series of environmental and health problems. On the other hand, metals like gold and copper are very valuable and are important to recover from WMMs. In the present study, an effective and environmental friendly method using supercritical water (SCW) to decompose BER and recover metals from WMMs was developed instead of hydrometallurgy or pyrometallurgy simultaneously. Experiments were conducted under external-catalyst-free conditions with temperatures ranging from 350 to 550 °C, pressures from 25 to 40 MPa, and reaction times from 120 to 360 min in a semibatch-type reactor. The results showed that BER could be quickly and efficiently decomposed under SCW condition, and the mechanism was possibly free radical reaction. After the SCW treatments, the glass fibers and metal foils in the solid residue could be easily liberated and recovered, respectively. The metal recovery rate reached 99.80%. The optimal parameters were determined as 495 °C, 33 MPa, and 305 min on the basis of response surface methodology (RSM). This study provides an efficient and environmental friendly approach for WMMs recycling compared with electrolysis, pyrometallurgy, and hydrometallurgy.

  16. Catalytic supercritical water gasification of primary paper sludge using a homogeneous and heterogeneous catalyst: Experimental vs thermodynamic equilibrium results.

    Science.gov (United States)

    Louw, Jeanne; Schwarz, Cara E; Burger, Andries J

    2016-02-01

    H2, CH4, CO and CO2 yields were measured during supercritical water gasification (SCWG) of primary paper waste sludge (PWS) at 450°C. Comparing these yields with calculated thermodynamic equilibrium values offer an improved understanding of conditions required to produce near-equilibrium yields. Experiments were conducted at different catalyst loads (0-1g/gPWS) and different reaction times (15-120min) in a batch reactor, using either K2CO3 or Ni/Al2O3-SiO2 as catalyst. K2CO3 up to 1g/gPWS increased the H2 yield significantly to 7.5mol/kgPWS. However, these yields and composition were far from equilibrium values, with carbon efficiency (CE) and energy recovery (ER) of only 29% and 20%, respectively. Addition of 0.5-1g/gPWS Ni/Al2O3-SiO2 resulted in high H2 and CH4 yields (6.8 and 14.8mol/kgPWS), CE of 84-90%, ER of 83% and a gas composition relatively close to the equilibrium values (at hold times of 60-120min).

  17. In situ mid-infrared spectroscopic titration of forsterite with water in supercritical CO2: Dependence of mineral carbonation on quantitative water speciation

    Science.gov (United States)

    Loring, J. S.; Thompson, C. J.; Wang, Z.; Schaef, H. T.; Martin, P.; Qafoku, O.; Felmy, A. R.; Rosso, K. M.

    2011-12-01

    Geologic sequestration of carbon dioxide holds promise for helping mitigate CO2 emissions generated from the burning of fossil fuels. Supercritical CO2 (scCO2) plumes containing variable water concentrations (wet scCO2) will displace aqueous solution and dominate the pore space adjacent to caprocks. It is important to understand possible mineral reactions with wet scCO2 to better predict long-term caprock integrity. We introduce novel in situ instrumentation that enables quantitative titrations of reactant minerals with water in scCO2 at temperatures and pressures relevant to target geologic reservoirs. The system includes both transmission and attenuated total reflection mid-infrared optics. Transmission infrared spectroscopy is used to measure concentrations of water dissolved in the scCO2, adsorbed on mineral surfaces, and incorporated into precipitated carbonates. Single-reflection attenuated total reflection infrared spectroscopy is used to monitor water adsorption, mineral dissolution, and carbonate precipitation reactions. Results are presented for the infrared spectroscopic titration of forsterite (Mg2SiO4), a model divalent metal silicate, with water in scCO2 at 100 bar and at both 50 and 75°C. The spectral data demonstrate that the quantitative speciation of water as either dissolved or adsorbed is important for understanding the types, growth rates, and amounts of carbonate precipitates formed. Relationships between dissolved/adsorbed water, water concentrations, and the role of liquid-like adsorbed water are discussed. Our results unify previous in situ studies from our laboratory based on infrared spectroscopy, nuclear magnetic resonance spectroscopy and X-ray diffraction.

  18. Hydrodynamics and Mass Transfer Performance in Supercritical Fluid Extraction Columns

    Institute of Scientific and Technical Information of China (English)

    石冰洁; 张泽廷; 等

    2002-01-01

    New models for describing hydrodynamics and mass transfer performance in supercritical fluid extraction columns were proposed.Those models were proved by experimental data,which were obtained in supercritical fluid extraction packed column,spray column and sieve tray column respectively.The inner diameter of those columns areΦ25mm,These experimental systems include supercritical carbon dioxideisopropanol-water and supercritical carbon dioxide-ethanol-water,in which supercritical carbon dioxide was dispersed phase,and another was continuous phase.The extraction processes were operated with continuous countercurrent flow.The predicted values are agreed well with experimental data.

  19. Simultaneous analysis for water- and fat-soluble vitamins by a novel single chromatography technique unifying supercritical fluid chromatography and liquid chromatography.

    Science.gov (United States)

    Taguchi, Kaori; Fukusaki, Eiichiro; Bamba, Takeshi

    2014-10-03

    Chromatography techniques usually use a single state in the mobile phase, such as liquid, gas, or supercritical fluid. Chromatographers manage one of these techniques for their purpose but are sometimes required to use multiple methods, or even worse, multiple techniques when the target compounds have a wide range of chemical properties. To overcome this challenge, we developed a single method covering a diverse compound range by means of a "unified" chromatography which completely bridges supercritical fluid chromatography and liquid chromatography. In our method, the phase state was continuously changed in the following order; supercritical, subcritical and liquid. Moreover, the gradient of the mobile phase starting at almost 100% CO2 was replaced with 100% methanol at the end completely. As a result, this approach achieved further extension of the polarity range of the mobile phase in a single run, and successfully enabled the simultaneous analysis of fat- and water-soluble vitamins with a wide logP range of -2.11 to 10.12. Furthermore, the 17 vitamins were exceptionally separated in 4min. Our results indicated that the use of dense CO2 and the replacement of CO2 by methanol are practical approaches in unified chromatography covering diverse compounds. Additionally, this is a first report to apply the novel approach to unified chromatography, and can open another door for diverse compound analysis in a single chromatographic technique with single injection, single column and single system.

  20. Comparison of large scale purification processes of naproxen enantiomers by chromatography using methanol-water and methanol-supercritical carbon dioxide mobile phases.

    Science.gov (United States)

    Kamarei, Fahimeh; Vajda, Péter; Guiochon, Georges

    2013-09-20

    This paper compares two methods used for the preparative purification of a mixture of (S)-, and (R)-naproxen on a Whelk-O1 column, using either high performance liquid chromatography or supercritical fluid chromatography. The adsorption properties of both enantiomers were measured by frontal analysis, using methanol-water and methanol-supercritical carbon dioxide mixtures as the mobile phases. The measured adsorption data were modeled, providing the adsorption isotherms and their parameters, which were derived from the nonlinear fit of the isotherm models to the experimental data points. The model used was a Bi-Langmuir isotherm, similar to the model used in many enantiomeric separations. These isotherms were used to calculate the elution profiles of overloaded elution bands, assuming competitive Bi-Langmuir behavior of the two enantiomers. The analysis of these profiles provides the basis for a comparison between supercritical fluid chromatographic and high performance liquid chromatographic preparative scale separations. It permits an illustration of the advantages and disadvantages of these methods and a discussion of their potential performance.

  1. Investigation of Wyoming Bentonite Hydration in Dry to Water-Saturated Supercritical CO2: Implications for Caprock Integrity

    Science.gov (United States)

    Loring, J. S.; Chen, J.; Thompson, C.; Schaef, T.; Miller, Q. R.; Martin, P. F.; Ilton, E. S.; Qafoku, O.; Felmy, A. R.; Rosso, K. M.

    2012-12-01

    The effectiveness of geologic sequestration as an enterprise for CO2 storage depends partly on the reactivity of supercritical CO2 (scCO2) with caprock minerals. Injection of scCO2 will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water-saturated scCO2. Caprock formations have high concentrations of clay minerals, including expandable montmorillonites. Water-bearing scCO2 is highly reactive and capable of hydrating or dehydrating clays, possibly leading to porosity and permeability changes that directly impact caprock performance. Dehydration will cause montmorillonite clay minerals in caprocks to contract, thereby decreasing solid volume and possibly increasing caprock permeability and porosity. On the other hand, water intercalation will cause these clays to expand, thereby increasing solid volume and possibly leading to self-sealing of caprock fractures. Pacific Northwest National Laboratory's Carbon Sequestration Initiative is developing capabilities for studying wet scCO2-mineral reactions in situ. Here, we introduce novel in situ infrared (IR) spectroscopic instrumentation that enables quantitative titrations of reactant minerals with water in scCO2. Results are presented for the infrared spectroscopic titrations of Na-, Ca-, and Mg-saturated Wyoming betonites with water over concentrations ranging from zero to scCO2 saturated. These experiments were carried out at 50°C and 90 bar. Transmission IR spectroscopy was used to measure concentrations of water dissolved in the scCO2 or intercalated into the clays. The titration curves evaluated from the transmission-IR data are compared between the three types of clays to assess the effects of the cation on water partitioning. Single-reflection attenuated total reflection (ATR) IR spectroscopy was used to collect the spectrum of the clays as they hydrate at every total water concentration during the titration. Clay hydration is evidenced by

  2. Subcritical and supercritical water oxidation of organic, wet wastes for carbon cycling in regenerative life support systems

    Science.gov (United States)

    Ronsse, Frederik; Lasseur, Christophe; Rebeyre, Pierre; Clauwaert, Peter; Luther, Amanda; Rabaey, Korneel; Zhang, Dong Dong; López Barreiro, Diego; Prins, Wolter; Brilman, Wim

    2016-07-01

    For long-term human spaceflight missions, one of the major requirements is the regenerative life support system which has to be capable of recycling carbon, nutrients and water from both solid and liquid wastes generated by the crew and by the local production of food through living organisms (higher plants, fungi, algae, bacteria, …). The European Space Agency's Life Support System, envisioned by the MELiSSA project, consists of a 5 compartment artificial ecosystem, in which the waste receiving compartment (so-called compartment I or briefly 'CI') is based on thermophilic fermentation. However, as the waste generated by the crew compartment and food production compartment contain typical plant fibres (lignin, cellulose and hemicellulose), these recalcitrant fibres end up largely unaffected in the digestate (sludge) generated in the C-I compartment. Therefore, the C-I compartment has to be supplemented with a so-called fibre degradation unit (in short, FDU) for further oxidation or degradation of said plant fibres. A potential solution to degrading these plant fibres and other recalcitrant organics is their oxidation, by means of subcritical or supercritical water, into reusable CO2 while retaining the nutrients in an organic-free liquid effluent. By taking advantage of the altered physicochemical properties of water above or near its critical point (647 K, 22.1 MPa) - including increased solubility of non-polar compounds and oxygen, ion product and diffusivity - process conditions can be created for rapid oxidation of C into CO2. In this research, the oxidizer is provided as a hydrogen peroxide solution which, at elevated temperature, will dissociated into O2. The purpose of this study is to identify ideal process conditions which (a) ensure complete oxidation of carbon, (b) retaining the nutrients other than C in the liquid effluent and (c) require as little oxidizer as possible. Experiments were conducted on a continuous, tubular heated reactor and on batch

  3. Discrimination of FAC features and threats in feed water and drainage systems of supercritical and ultra-supercritical units%超(超)临界锅炉给水疏水系统流动加速腐蚀特征和风险辨识

    Institute of Scientific and Technical Information of China (English)

    黄兴德; 游喆; 赵泓; 王国蓉; 顾庆华; 祝青

    2011-01-01

    Combining with the matter transporting model of the water (steam) -metal and the theory of FAC ( Flow Accelerated Corrosion ),FAC is determined as the ultimate causation for the numerous chemical problems in common of supercritical and ultra-supercritical units.Clear discrimination, early warning and effectively restraining of FAC features of supercritical units could be utilized to substantially improve the operation quality. FAC situation assessment should be carried out in supercritical and ultra-supercritical units with AVT for feed water.%结合水(汽)与炉管接触反应界而的氧化层(膜)的物质输送模型和流动加速腐蚀(FAC)研究理论.确定FAC是超(超)临界机组运行中暴露的众多共性化学问题的根本原因.通过对超(超)临界机组FAC特征的识别、预警和有效抑制,有助于提高超临界机组的安全经济运行水平.采用给水伞挥发性处理的超(超)临界机组.要加强对FAC现象及特征的评估.

  4. NMR study comparing capillary trapping in Berea sandstone of air, carbon dioxide, and supercritical carbon dioxide after imbibition of water

    Science.gov (United States)

    Prather, Cody A.; Bray, Joshua M.; Seymour, Joseph D.; Codd, Sarah L.

    2016-02-01

    Nuclear magnetic resonance (NMR) techniques were used to study the capillary trapping mechanisms relevant to carbon sequestration. Capillary trapping is an important mechanism in the initial trapping of supercritical CO2 in the pore structures of deep underground rock formations during the sequestration process. Capillary trapping is considered the most promising trapping option for carbon sequestration. NMR techniques noninvasively monitor the drainage and imbibition of air, CO2, and supercritical CO2 with DI H2O at low capillary numbers in a Berea sandstone rock core under conditions representative of a deep underground saline aquifer. Supercritical CO2 was found to have a lower residual nonwetting (NW) phase saturation than that of air and CO2. Supercritical CO2 behaves differently than gas phase air or CO2 and leads to a reduction in capillary trapping. NMR relaxometry data suggest that the NW phase, i.e., air, CO2, or supercritical CO2, is preferentially trapped in larger pores. This is consistent with snap-off conditions being more favorable in macroscale pores, as NW fluids minimize their contact area with the solid and hence prefer larger pores.

  5. Quantifying the flow dynamics of supercritical CO2-water displacement in a 2D porous micromodel using fluorescent microscopy and microscopic PIV

    Science.gov (United States)

    Kazemifar, Farzan; Blois, Gianluca; Kyritsis, Dimitrios C.; Christensen, Kenneth T.

    2016-09-01

    The multi-phase flow of liquid/supercritical CO2 and water (non-wetting and wetting phases, respectively) in a two-dimensional silicon micromodel was investigated at reservoir conditions (80 bar, 24 °C and 40 °C). The fluorescent microscopy and microscopic particle image velocimetry (micro-PIV) techniques were combined to quantify the flow dynamics associated with displacement of water by CO2 (drainage) in the porous matrix. To this end, water was seeded with fluorescent tracer particles, CO2 was tagged with a fluorescent dye and each phase was imaged independently using spectral separation in conjunction with microscopic imaging. This approach allowed simultaneous measurement of the spatially-resolved instantaneous velocity field in the water and quantification of the spatial configuration of the two fluid phases. The results, acquired with sufficient time resolution to follow the dynamic progression of both phases, provide a comprehensive picture of the flow physics during the migration of the CO2 front, the temporal evolution of individual menisci, and the growth of fingers within the porous microstructure. During that growth process, velocity jumps 20-25 times larger in magnitude than the bulk velocity were measured in the water phase and these bursts of water flow occurred both in-line with and against the bulk flow direction. These unsteady velocity events support the notion of pressure bursts and Haines jumps during pore drainage events as previously reported in the literature [1-3]. After passage of the CO2 front, shear-induced flow was detected in the trapped water ganglia in the form of circulation zones near the CO2-water interfaces as well as in the thin water films wetting the surfaces of the silicon micromodel. To our knowledge, the results presented herein represent the first quantitative spatially and temporally resolved velocity-field measurements at high pressure for water displacement by liquid/supercritical CO2 injection in a porous micromodel.

  6. In-situ Optical Spectroscopy Investigation of Water and Its influence on Forsterite Transformation in Supercritical CO2

    Science.gov (United States)

    Wang, Z.; Thompson, C. J.; Joly, A. G.; Sklarew, D. S.; Poindexter, L.; Rosso, K. M.

    2009-12-01

    Carbon capture and sequestration (CCS) from coal/gas-burning power plants is currently viewed as one of the most promising technologies for mitigating green house gas emissions. This strategy involves injection of supercritical CO2 (scCO2) into deep geological formations such as depleted oil and gas reservoirs and deep saline aquifers. The feasibility of this approach and the ultimate fate of the stored CO2 are determined by the interactions between scCO2, various minerals in the rock formations, and the host fluids. Currently, there is only limited knowledge about both the thermodynamic and kinetic aspects of the physical and chemical processes that occur between scCO2 and relevant minerals, such as metal silicates and metal aluminosilicates, and the role of water activity for catalyzing mineral transformation reactions. In this work, we have developed a modular in situ optical spectroscopic platform that integrates a scCO2 generation and manipulation system with an array of optical and laser spectroscopies including UV-visible, IR, Raman and laser fluorescence spectroscopy. We have used the system to study i) the dissolution and quantification of H2O/D2O in scCO2 and ii) interaction between scCO2 and a model metal silicate, forsterite (Mg2SiO4), and the effects of the presence of water under variable pressure, temperature and water content. Our results showed that H2O and D2O have unique IR spectral features over a broad spectral range from 700 cm-1 to ~ 2900 cm-1 in scCO2 and their concentrations are directly proportional to the characteristic IR bands that correspond to their stretching (D2O) and bending frequencies (both D2O and H2O). These bands offer a unique spectroscopic signature useful for qualitative and quantitative analysis of the properties and reactivity of small amounts of H2O in scCO2.

  7. Study on the Diffusion Coefficient of Sodium Chloride at Infinite Dilution in Supercritical Water%超临界水中NaCl无限稀释扩散系数的研究

    Institute of Scientific and Technical Information of China (English)

    肖吉; 陆九芳; 陈健; 李以圭

    2003-01-01

    The molecular dynamics (MD) was employed to simulate the diffusion coefficient of sodium chloride at infinite dilution in supercritical water from 703.2 K to 763.2 K and from 30 MPa to 45 MPa. Based on the simulated data and the Patel-Teja(PT) equation of state and the Liu-Ruckenstein equation, an equation for calculating the diffusion coefficient of NaCl at infinite dilution in supercritical water is proposed. Both the agreement between the simulated and correlated data, and that between the simulated and predicted data of diffusion coefficients for NaCl in supercritical water ranging from 703.2 K to 803.2 K and from 25 MPa to 50 MPa show that this equation is applicable for the calculation of diffusion coefficients.

  8. Supercritical fluid chromatographic resolution of water soluble isomeric carboxyl/amine terminated peptides facilitated via mobile phase water and ion pair formation.

    Science.gov (United States)

    Patel, M A; Riley, F; Ashraf-Khorassani, M; Taylor, L T

    2012-04-13

    Both analytical scale and preparative scale packed column supercritical fluid chromatography (SFC) have found widespread applicability for chiral separations of multiple polar pharmaceutical candidates. However, SFC is rapidly becoming an achiral technique. More specifically, ion pair SFC is finding greater utility for separation of ionic analytes such as amine salts and organic sulfonates. The key to this success is, in part, the incorporation of additives such as trifluoroacetic acid and ammonium acetate into the mobile phase in association with a wide variety of both bonded silica stationary phases and high purity bare silica. Ion pairing SFC coupled with evaporative light scattering detection and mass spectrometric detection is presented here for the separation of water soluble, uncapped, isomeric peptide pairs that differ in amino acid arrangement. The separation is best achieved on either diol-bonded silica or bare silica with 1-5% (w/w) water as a significant ingredient in the mobile phase. Nitrogenous stationary phases such as 2-ethylpyridine, which had been very successful for the separation of capped peptides failed to yield the desired separation regardless of the mobile phase composition. A HILIC type retention mechanism is postulated for the separation of both isomeric uncapped peptide pairs.

  9. Corrosion and microstructural analysis data for AISI 316L and AISI 347H stainless steels after exposure to a supercritical water environment.

    Science.gov (United States)

    Ruiz, A; Timke, T; van de Sande, A; Heftrich, T; Novotny, R; Austin, T

    2016-06-01

    This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C) with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure.

  10. Corrosion and microstructural analysis data for AISI 316L and AISI 347H stainless steels after exposure to a supercritical water environment

    Directory of Open Access Journals (Sweden)

    A. Ruiz

    2016-06-01

    Full Text Available This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure.

  11. Lewis acid-catalyzed depolymerization of soda lignin in supercritical ethanol/water mixtures

    NARCIS (Netherlands)

    Güvenatam, Burcu; Heeres, Erik H.J.; Pidko, Evgeny A.; Hensen, Emiel J M

    2016-01-01

    The depolymerization of lignin model compounds and soda lignin by super Lewis acidic metal triflates has been investigated in a mixture of ethanol and water at 400 °C. The strong Lewis acids convert representative model compounds for the structure-forming linkages in lignin, namely α-O-4, 5-O-4

  12. The influence of water and supercritical CO2 on the failure behavior of chalk

    NARCIS (Netherlands)

    Liteanu, E.; Spiers, C.J.; de Bresser, J.H.P.

    2013-01-01

    Reduction of compressive strength by injection of water into chalk is a well-known mechanism responsible for increased compaction in chalk reservoirs. This raises the question of whether such effects might be enhanced in the context of long-term storage of CO2 or of CO2 injection for enhanced oil

  13. Determination of Organic Partitioning Coefficients in Water-Supercritical CO 2 Systems by Simultaneous in Situ UV and Near-Infrared Spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Bryce, David A.; Shao, Hongbo; Cantrell, Kirk J.; Thompson, Christopher J.

    2016-06-07

    CO2 injected into depleted oil or gas reservoirs for long-term storage has the potential to mobilize organic compounds and distribute them between sediments and reservoir brines. Understanding this process is important when considering health and environmental risks, but little quantitative data currently exists on the partitioning of organics between supercritical CO2 and water. In this work, a high-pressure, in situ measurement capability was developed to assess the distribution of organics between CO2 and water at conditions relevant to deep underground storage of CO2. The apparatus consists of a titanium reactor with quartz windows, near-infrared and UV spectroscopic detectors, and switching valves that facilitate quantitative injection of organic reagents into the pressurized reactor. To demonstrate the utility of the system, partitioning coefficients were determined for benzene in water/supercritical CO2 over the range 35-65 °C and approximately 25-150 bar. Density changes in the CO2 phase with increasing pressure were shown to have dramatic impacts on benzene's partitioning behavior. Our partitioning coefficients were approximately 5-15 times lower than values previously determined by ex situ techniques that are prone to sampling losses. The in situ methodology reported here could be applied to quantify the distribution behavior of a wide range of organic compounds that may be present in geologic CO2 storage scenarios.

  14. Electronic transport in partially ionized water plasmas

    Science.gov (United States)

    French, Martin; Redmer, Ronald

    2017-09-01

    We use ab initio simulations based on density functional theory to calculate the electrical and thermal conductivities of electrons in partially ionized water plasmas at densities above 0.1 g/cm3. The resulting conductivity data are then fitted to analytic expressions for convenient application. For low densities, we develop a simple and fully analytic model for electronic transport in low-density plasmas in the chemical picture using the relaxation-time approximation. In doing so, we derive a useful analytic expression for electronic transport cross sections with neutral particles, based on a model potential. In the regime of thermal ionization, electrical conductivities from the analytic model agree with the ab initio data within a factor of 2. Larger deviations are observed for the thermal conductivity, and their origin is discussed. Our results are relevant for modeling the interior and evolution of water-rich planets as well as for technical plasma applications.

  15. Preliminary Corrosion Studies of Candidate Materials for Supercritical Water Oxidation Reactor Systems

    Science.gov (United States)

    1994-05-01

    Techniques 80 Chapter 5: Results and Discussion of Results 82 5.1 Visual Observations 83 5.2 Fibre Optic Microscopic Observation 84 5.3 Laser Confocal...Shutoff Controller 137 E-8 Labview® Alarm Warning Circuit 138 E-9 Labview® Audible Alarm Circuit 141 G-1 Fibre - Optic Microscope View of Inconel 625...Exposed to 145 Deionized Water for 96 hrs. at 500’C, 241.5 atm, Washer Transition Region. (100 x) G-2 Fibre - Optic Microscope View of Hastelloy C-276

  16. Thermodynamic Analysis of the Use a Chemical Heat Pump to Link a Supercritical Water-Cooled Nuclear Reactor and a Thermochemical Water-Splitting Cycle for Hydrogen Production

    Science.gov (United States)

    Granovskii, Mikhail; Dincer, Ibrahim; Rosen, Marc A.; Pioro, Igor

    Increases in the power generation efficiency of nuclear power plants (NPPs) are mainly limited by the permissible temperatures in nuclear reactors and the corresponding temperatures and pressures of the coolants in reactors. Coolant parameters are limited by the corrosion rates of materials and nuclear-reactor safety constraints. The advanced construction materials for the next generation of CANDU reactors, which employ supercritical water (SCW) as a coolant and heat carrier, permit improved “steam” parameters (outlet temperatures up to 625°C and pressures of about 25 MPa). An increase in the temperature of steam allows it to be utilized in thermochemical water splitting cycles to produce hydrogen. These methods are considered by many to be among the most efficient ways to produce hydrogen from water and to have advantages over traditional low-temperature water electrolysis. However, even lower temperature water splitting cycles (Cu-Cl, UT-3, etc.) require an intensive heat supply at temperatures higher than 550-600°C. A sufficient increase in the heat transfer from the nuclear reactor to a thermochemical water splitting cycle, without jeopardizing nuclear reactor safety, might be effectively achieved by application of a heat pump, which increases the temperature of the heat supplied by virtue of a cyclic process driven by mechanical or electrical work. Here, a high-temperature chemical heat pump, which employs the reversible catalytic methane conversion reaction, is proposed. The reaction shift from exothermic to endothermic and back is achieved by a change of the steam concentration in the reaction mixture. This heat pump, coupled with the second steam cycle of a SCW nuclear power generation plant on one side and a thermochemical water splitting cycle on the other, increases the temperature of the “nuclear” heat and, consequently, the intensity of heat transfer into the water splitting cycle. A comparative preliminary thermodynamic analysis is conducted

  17. Micro-PIV Study of Supercritical CO2-Water Interactions in Porous Micromodels

    Science.gov (United States)

    Kazemifar, Farzan; Blois, Gianluca; Christensen, Kenneth T.

    2015-11-01

    Multiphase flow of immiscible fluids in porous media is encountered in numerous natural systems and engineering applications such as enhanced oil recovery (EOR), and CO2 sequestration among others. Geological sequestration of CO2 in saline aquifers has emerged as a viable option for reducing CO2 emissions, and thus it has been the subject of numerous studies in recent years. A key objective is improving the accuracy of numerical models used for field-scale simulations by incorporation/better representation of the pore-scale flow physics. This necessitates experimental data for developing, testing and validating such models. We have studied drainage and imbibition processes in a homogeneous, two-dimensional porous micromodel with CO2 and water at reservoir-relevant conditions. Microscopic particle image velocimetry (micro-PIV) technique was applied to obtain spatially- and temporally-resolved velocity vector fields in the aqueous phase. The results provide new insight into the flow processes at the pore scale.

  18. Probing Lewis Acid-Base Interactions with Born-Oppenheimer Molecular Dynamics: The Electronic Absorption Spectrum of p-Nitroaniline in Supercritical CO2.

    Science.gov (United States)

    Cabral, Benedito J Costa; Rivelino, Roberto; Coutinho, Kaline; Canuto, Sylvio

    2015-07-02

    The structure and dynamics of p-nitroaniline (PNA) in supercritical CO2 (scCO2) at T = 315 K and ρ = 0.81 g cm(-3) are investigated by carrying out Born-Oppenheimer molecular dynamics, and the electronic absorption spectrum in scCO2 is determined by time dependent density functional theory. The structure of the PNA-scCO2 solution illustrates the role played by Lewis acid-base (LA-LB) interactions. In comparison with isolated PNA, the ν(N-O) symmetric and asymmetric stretching modes of PNA in scCO2 are red-shifted by -17 and -29 cm(-1), respectively. The maximum of the charge transfer (CT) absorption band of PNA in scSCO2 is at 3.9 eV, and the predicted red-shift of the π → π* electronic transition relative to the isolated gas-phase PNA molecule reproduces the experimental value of -0.35 eV. An analysis of the relationship between geometry distortions and excitation energies of PNA in scCO2 shows that the π → π* CT transition is very sensitive to changes of the N-O bond distance, strongly indicating a correlation between vibrational and electronic solvatochromism driven by LA-LB interactions. Despite the importance of LA-LB interactions to explain the solvation of PNA in scCO2, the red-shift of the CT band is mainly determined by electrostatic interactions.

  19. 超临界W火焰锅炉水冷壁特性研究%Study on Characteristic of Water Wall in Supercritical W-flame Boiler

    Institute of Scientific and Technical Information of China (English)

    毛天

    2015-01-01

    According to the research of a power plant W supercritical boiler water cooling wall of flame characteristics of the analy-sis, put forward to solve the vibration of the middle row of technical measures such as the wall temperature, the water wall leakage and central crack front wall water-cooling wall tube.%对某电厂超临界W火焰锅炉水冷壁特性进行介绍,提出解决前墙水冷壁中部超温、前墙水冷壁中部拉裂泄漏和前墙水冷壁管排振动大的方法。

  20. Preparation and Investigation Performance of Water- Based Epoxy Coating Containing Supercritical CO2 Synthesized SelfDoped Polyaniline-Expanded Graphite Nanohybrids As A Anti Corrosion Pigment

    Directory of Open Access Journals (Sweden)

    M.R.Baghezadeh

    2017-03-01

    Full Text Available In this research, self- doped polyaniline- expanded graphite nanohybrid (SPEG was synthesized by supercritical CO2 method and the anti-corrosion performance of SPEG in water- based epoxy coatings was considered. For this purpose, SPEG was introduced into water- based hardener and epoxy resin, separately via direct mixing under an ultrasonic homogenizer. The distribution of SPEG in both matrices was studied by zeta sizer, XRD and TEM characterization methods. The corrosion behavior of coatings was characterized salt spray and electrochemical impedance spectroscopy (EIS in 3.5 % NaCl solution. The results showed that coatings prepared by using SPEG in water-based hardener had the best corrosion resistance.

  1. Effect on nickel loading on hydrogen production and chemical oxygen demand (COD) destruction from glucose oxidation and gasification in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Youssef, E.A.; Chowdhury, M.B.I.; Nakhla, G.; Charpentier, P. [Western Ontario University, London, ON (Canada). Dept. of Biochemical and Chemical Engineering

    2009-07-01

    Hydrogen produced from biomass is considered to be an excellent alternative to the use of fossil fuels. Gasification and partial oxidation of glucose was performed in the presence of different metallic nickel (Ni) loadings on different catalyst supports in supercritical water at three temperature levels. For comparison, some experiments were conducted using high loading commercial catalyst Ni on silica-alumina. Hydrogen peroxide was used as a source of oxygen in the partial oxidation experiments. Oxygen to carbon stoichiometric ratios of 0.5 to 0.9 were examined to increase the hydrogen production via carbon monoxide production. The paper described the experimental and methods as well as results and discussion. Results showed that in the absence of catalyst, the optimum stoichiometric ratio was 0.8 of the amount of oxygen required for complete oxidation of glucose. It was concluded that enhancing hydrogen yield and selectivity from glucose by obtaining the desired catalytic property and the optimum process conditions and parameters would be an invaluable addition to the supercritical water oxidation technology. 24 refs., 2 tabs., 5 figs.

  2. A comparison of chilled DI water/ozone and CO{sub 2}-based supercritical fluids as replacements for photoresist-stripping solvents

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J.B.; Davenhall, L.B.; Barton, J.; Taylor, C.M.V. [Los Alamos National Lab., NM (United States). Chemical Science and Technology Div.; Tiefert, K. [Hewlett-Packard Co., Santa Clara, CA (United States)

    1998-12-31

    Part of the Hewlett Packard Components Group`s Product Stewardship program is the ongoing effort to investigate ways to eliminate or reduce as much as possible the use of chemical substances from manufacturing processes. Currently used techniques to remove hard-baked photoresists from semiconductor wafers require the use of inorganic chemicals or organic strippers and associated organic solvents. Environmental, health and safety, as well as cost considerations prompted the search for alternative, more environmentally-benign, and cost-effective solutions. Two promising, emerging technologies were selected for evaluation: the chilled DI water/ozone technique and supercritical fluids based on carbon dioxide (CO{sub 2}). Evaluating chilled DI water/ozone shows this process to be effective for positive photoresist removal, but may not be compatible with all metallization systems. Testing of a closed-loop CO{sub 2}-based supercritical CO{sub 2} Resist Remover, or SCORR, at Los Alamos, on behalf of Hewlett-packard, shows that this treatment process is effective in removing photoresists, and is fully compatible with commonly used metallization systems. In this paper, the authors present details on the testing programs conducted with both the chilled DI H{sub 2}O/ozone and SCORR treatment processes.

  3. Influence of the reactant carbon-hydrogen-oxygen composition on the key products of the direct gasification of dewatered sewage sludge in supercritical water.

    Science.gov (United States)

    Gong, Miao; Zhu, Wei; Fan, Yujie; Zhang, Huiwen; Su, Ying

    2016-05-01

    The supercritical water gasification of ten different types of dewatered sewage sludges was investigated to understand the relationship between sludge properties and gasification products. Experiments were performed in a high-pressure autoclave at 400°C for 60 min. Results showed that gasification of sewage sludge in supercritical water consists mainly of a gasification reaction, a carbonization reaction and a persistent organic pollutants synthesis reaction. Changes in the reactant C/H/O composition have significant effects on the key gasification products. Total gas production increased with increasing C/H2O of the reactant. The char/coke content increased with increasing C/H ratio of the reactant. A decrease in the C/O ratio of the reactant led to a reduction in polycyclic aromatic hydrocarbon formation. This means that we can adjust the reactant C/H/O composition by adding carbon-, hydrogen-, and oxygen-containing substances such as coal, algae and H2O2 to optimize hydrogen production and to inhibit an undesired by-product formation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Pulsed supercritical synthesis of anatase TiO₂ nanoparticles in a water-isopropanol mixture studied by in situ powder X-ray diffraction.

    Science.gov (United States)

    Rostgaard Eltzholtz, Jakob; Tyrsted, Christoffer; Ørnsbjerg Jensen, Kirsten Marie; Bremholm, Martin; Christensen, Mogens; Becker-Christensen, Jacob; Brummerstedt Iversen, Bo

    2013-03-21

    A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania nanoparticles were synthesized in a 50/50 mixture of water and isopropanol near and above the critical point of water (P = 250 bar, T = 300, 350, 400, 450, 500 and 550 °C). The evolution of the reaction product was followed by sequentially recording PXRD patterns with a time resolution of less than two seconds. The crystallite size of titania is found to depend on both temperature and residence time, and increasing either parameter leads to larger crystallites. A simple adjustment of either temperature or residence time provides a direct method for gram scale production of anatase nanoparticles of average crystallite sizes between 7 and 35 nm, thus giving the option of synthesizing tailor-made nanoparticles. Modeling of the in situ growth curves using an Avrami growth model gave an activation energy of 66(19) kJ mol(-1) for the initial crystallization. The in situ PXRD data also provide direct information about the size dependent macrostrain in the nanoparticles and with decreasing crystallite size the unit cell contracts, especially along the c-direction. This agrees well with previous ex situ results obtained for hydrothermal synthesis of titania nanoparticles.

  5. Corrosion in supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Propp, W.A.; Carleson, T.E.; Wai, Chen M.; Taylor, P.R.; Daehling, K.W.; Huang, Shaoping; Abdel-Latif, M.

    1996-05-01

    Integrated studies were carried out in the areas of corrosion, thermodynamic modeling, and electrochemistry under pressure and temperature conditions appropriate for potential applications of supercritical fluid (SCF) extractive metallurgy. Carbon dioxide and water were the primary fluids studied. Modifiers were used in some tests; these consisted of 1 wt% water and 10 wt% methanol for carbon dioxide and of sulfuric acid, sodium sulfate, ammonium sulfate, and ammonium nitrate at concentrations ranging from 0.00517 to 0.010 M for the aqueous fluids. The materials studied were Types 304 and 316 (UNS S30400 and S31600) stainless steel, iron, and AISI-SAE 1080 (UNS G10800) carbon steel. The thermodynamic modeling consisted of development of a personal computer-based program for generating Pourbaix diagrams at supercritical conditions in aqueous systems. As part of the model, a general method for extrapolating entropies and related thermodynamic properties from ambient to SCF conditions was developed. The experimental work was used as a tool to evaluate the predictions of the model for these systems. The model predicted a general loss of passivation in iron-based alloys at SCF conditions that was consistent with experimentally measured corrosion rates and open circuit potentials. For carbon-dioxide-based SCFs, measured corrosion rates were low, indicating that carbon steel would be suitable for use with unmodified carbon dioxide, while Type 304 stainless steel would be suitable for use with water or methanol as modifiers.

  6. Kinetic investigation of the oxidation of naval excess hazardous materials in supercritical water for the design of a transpiration-wall reactor

    Energy Technology Data Exchange (ETDEWEB)

    Rice, S.F.; Hanush, R.G.; Hunter, T.B. [and others

    1997-01-01

    Experiments were conducted in Sandia`s supercritical fluids reactor (SFR) to generate data for the design of a transpiration-wall supercritical water oxidation (SCWO) reactor. The reactor is intended for the disposal of hazardous material generated on naval vessels. The design parameters for the system require an accurate knowledge of destruction efficiency vs. time and temperature. Three candidate materials were selected for testing. The experiments consisted of oxidizing these materials in the SFR at isothermal conditions over the temperature range of 400-550C at 24.1 MPa. A small extrapolation of the results shows that these materials can be adequately destroyed (to 99.9% destruction removal efficiency, DRE, based on total organic carbon (TOC) in the effluent) in approximately 5 seconds at 600C. The results vary smoothly and predictably with temperature such that extrapolation to higher temperatures beyond the experimental capabilities of the SFR can be made with reasonable confidence. The preliminary design of the transpiration-wall reactor has a rapid heat-up section within the reactor vessel that requires the addition of a fuel capable of quickly reacting with oxygen at temperatures below 500C. Candidate alcohols and JP-5 jet fuel were evaluated in this context. Oxidation rates for the alcohols were examined using in situ Raman spectroscopy. In addition, the potential utility of supplying the oxidizer line with hydrogen peroxide as an additive to enhance rapid initiation of the feed at unusually low temperatures was investigated. Experiments were conducted in the Supercritical Constant Volume Reactor (SCVR) using hydrogen peroxide as the initial oxidizing species. The results show that this concept as a method of enhancing low temperature reactivity appears to fail because thermal decomposition of the hydrogen peroxide is more rapid than the fuel oxidation rate at low temperatures. 8 refs., 16 figs., 5 tabs.

  7. Supercritical Fluids Processing of Biomass to Chemicals and Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Norman K. [Iowa State Univ., Ames, IA (United States)

    2011-09-28

    The main objective of this project is to develop and/or enhance cost-effective methodologies for converting biomass into a wide variety of chemicals, fuels, and products using supercritical fluids. Supercritical fluids will be used both to perform reactions of biomass to chemicals and products as well as to perform extractions/separations of bio-based chemicals from non-homogeneous mixtures. This work supports the Biomass Program’s Thermochemical Platform Goals. Supercritical fluids are a thermochemical approach to processing biomass that, while aligned with the Biomass Program’s interests in gasification and pyrolysis, offer the potential for more precise and controllable reactions. Indeed, the literature with respect to the use of water as a supercritical fluid frequently refers to “supercritical water gasification” or “supercritical water pyrolysis.”

  8. 超临界水冷堆中子能谱计算及安全性分析%Neutron spectrum calculation and safety analysis for supercritical water-cooled reactor

    Institute of Scientific and Technical Information of China (English)

    汤晓斌; 谢芹; 耿长冉; 陈达

    2012-01-01

    超临界水堆是国际第Ⅳ代核能系统论坛推荐的六种第Ⅳ代核电反应堆堆型之一,与现有的轻水堆相比,具有热效率高、系统结构简单、造价低等优点.建立了MCNP程序下的超临界水堆堆芯物理计算模型,解决了燃料组件几何结构过于复杂精细难以建模的技术难题;考虑了堆芯轴向冷却剂密度的不均匀分布,计算并分析各区域的中子能谱分布;对失水事故下的超临界水冷堆安全性进行了分析,研究了不同区域冷却剂丢失程度对反应性及有效增殖系数的影响,表明所设计堆型具有较高的安全性;分析处理失水事故的应对措施,验证了使用注入硼水措施处理超临界水冷堆失水事故的可行性.%The supercritical water reactor is one of the six reactors recommended by Generation IV International Forum, Compared with existing light water reactors, the supercritical water reactor has advantages of high thermal efficiency, simplified system structure and low cost. The physical model of the supercritical water reactor is established with MCNP program in this paper, which solves the problem of intricate geometry of fuel assembly. The change of coolant density along the axis is considered and the neutron spectrum distribution of different regions of the core is calculated. The safety in loss of coolant accident for the supercritical water reactor and the effect of missing coolant in different regions on the reactivity and effective multiplication factor analyzed. The results show the supercritical water reactor core has high security. The countermeasures of loss of coolant accident is studied and the effectiveness of boron water cooling is validated. The research not only provide important reference for the construction and security analysis of the supercritical water reactor, but also has great significance for the application and development of the supercritical water reactor.

  9. Advanced degradation of brominated epoxy resin and simultaneous transformation of glass fiber from waste printed circuit boards by improved supercritical water oxidation processes.

    Science.gov (United States)

    Liu, Kang; Zhang, Zhiyuan; Zhang, Fu-Shen

    2016-10-01

    This work investigated various supercritical water oxidation (SCWO) systems, i.e. SCWO1 (only water), SCWO2 (water+H2O2) and SCWO3 (water+H2O2/NaOH), for waste printed circuit boards (PCBs) detoxification and recycling. Response surface methodology (RSM) was applied to optimize the operating conditions of the optimal SCWO3 systems. The optimal reaction conditions for debromination were found to be the NaOH of 0.21g, the H2O2 volume of 9.04mL, the time of 39.7min, maximum debromination efficiency of 95.14%. Variance analysis indicated that the factors influencing debromination efficiency was in the sequence of NaOH>H2O2>time. Mechanism studies indicated that the dissociated ions from NaOH in supercritical water promoted the debromination of brominated epoxy resins (BERs) through an elimination reaction and nucleophilic substitution. HO2, produced by H2O2 could induce the oxidation of phenol ring to open (intermediates of BERs), which were thoroughly degraded to form hydrocarbons, CO2, H2O and NaBr. In addition, the alkali-silica reaction between OH(-) and SiO2 induced the phase transformation of glass fibers, which were simultaneously converted into anorthite and albite. Waste PCBs in H2O2/NaOH improved SCWO system were fully degraded into useful products and simultaneously transformed into functional materials. These findings are helpful for efficient recycling of waste PCBs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Developing and Evaluating Candidate Materials for Generation IV Supercritical Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin Sung; Kim, Sung Ho; Hwang Sung Sik and others

    2006-03-15

    D.O levels. The strain rate was 1.5X10{sup -7} or 0.8X10{sup -7}/sec. In comparison with the stress-strain curve of T92 in a fully deaerated SCW (below 10 ppb D.O) T92 appeared to experience SCC in SCW of 100 or 500 D.O, showing the decrease of the elongation and the tensile strength. A part of the fracture surface reveals a brittle fracture manner. (3) Crack growth rate (CGR) of T91 specimen under cyclic strain in a SCW was investigated using CT specimens. The CGR's in 370 .deg. C water and 500 .deg. C SCW were about 40% faster than those in the atmosphere. (4) In SCW of 25 ppb D.O the corrosion resistance of Ti-modified austenitic stainless steel (D9) at 500 .deg. C was significantly better than that of type 316 stainless steel, and 9Cr Fe-base ODS alloy also showed a clearly better corrosion resistance than T92 (NF616) and T122 (HCM12A) steels. (by UW) Characterization of the Irradiation Behavior (1) Using the accelerator at KIGAM (Korea Institute of Geoscience and Mineral Resources), T91 and ODS alloy (MA956) specimens were irradiated with 8 MeV Fe{sup 4+} ions up to 1 dpa at room temperature. Nano-indentation tests were done on the cross sections of the irradiated specimens, and the hardness increase of T91 was about 15%, and that of MA956 was about 25%. (2) T122 and alloy 800H were irradiated with Ni ions at 500 .deg. C up to 5 dpa and 50 dpa respectively. In the case of T122 fine precipitates of V-Nb (about 50%V-17%Cr-12%Nb) were found in addition to the frequently observed M{sub 23}C{sub 6} carbide. In alloy 800H faulted dislocation loops were frequently observed with the fine precipitates containing Cr, Si and Al. However, cavities were not observed in both specimens. (3) One sides of the T91, T91CSL, T122 and HT 9 specimens were irradiated with 3 MeV protons at 400 and 500 .deg. C respectively, and the SCC tested in SCW. Only the irradiated HT9 specimen showed some clue to SCC through the decrease of the elongation and the reduction of area, but the

  11. Developing and Evaluating Candidate Materials for Generation IV Supercritical Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin Sung; Kim, Sung Ho; Hwang Sung Sik and others

    2006-03-15

    D.O levels. The strain rate was 1.5X10{sup -7} or 0.8X10{sup -7}/sec. In comparison with the stress-strain curve of T92 in a fully deaerated SCW (below 10 ppb D.O) T92 appeared to experience SCC in SCW of 100 or 500 D.O, showing the decrease of the elongation and the tensile strength. A part of the fracture surface reveals a brittle fracture manner. (3) Crack growth rate (CGR) of T91 specimen under cyclic strain in a SCW was investigated using CT specimens. The CGR's in 370 .deg. C water and 500 .deg. C SCW were about 40% faster than those in the atmosphere. (4) In SCW of 25 ppb D.O the corrosion resistance of Ti-modified austenitic stainless steel (D9) at 500 .deg. C was significantly better than that of type 316 stainless steel, and 9Cr Fe-base ODS alloy also showed a clearly better corrosion resistance than T92 (NF616) and T122 (HCM12A) steels. (by UW) Characterization of the Irradiation Behavior (1) Using the accelerator at KIGAM (Korea Institute of Geoscience and Mineral Resources), T91 and ODS alloy (MA956) specimens were irradiated with 8 MeV Fe{sup 4+} ions up to 1 dpa at room temperature. Nano-indentation tests were done on the cross sections of the irradiated specimens, and the hardness increase of T91 was about 15%, and that of MA956 was about 25%. (2) T122 and alloy 800H were irradiated with Ni ions at 500 .deg. C up to 5 dpa and 50 dpa respectively. In the case of T122 fine precipitates of V-Nb (about 50%V-17%Cr-12%Nb) were found in addition to the frequently observed M{sub 23}C{sub 6} carbide. In alloy 800H faulted dislocation loops were frequently observed with the fine precipitates containing Cr, Si and Al. However, cavities were not observed in both specimens. (3) One sides of the T91, T91CSL, T122 and HT 9 specimens were irradiated with 3 MeV protons at 400 and 500 .deg. C respectively, and the SCC tested in SCW. Only the irradiated HT9 specimen showed some clue to SCC through the decrease of the elongation and the reduction of area, but the

  12. Water as a Direct Hydrogen Donor in Supercritical Carbon Di-oxide: A Novel and Efficient Zn-H2O-CO2 System for Chemo selective Reduction of Nitrobenzenes to Anilines

    Institute of Scientific and Technical Information of China (English)

    JIANG Huan-Feng; DONG Yao-Sen

    2008-01-01

    An eco-friendly and cheap Zn-H2O-CO2 system was presented for chemoselective reduction of nitrobenzenes to anilines with high yields (80%-97% isolated yields) in supercritical carbon dioxide. This process brings together the very important green chemistry technologies--the use of carbon dioxide as a solvent and the use of water as a hydrogen donor.

  13. Effect of residence time on two-step liquefaction of rice straw in a CO2 atmosphere: Differences between subcritical water and supercritical ethanol.

    Science.gov (United States)

    Yang, Tianhua; Wang, Jian; Li, Bingshuo; Kai, Xingping; Li, Rundong

    2017-04-01

    This study investigated the influence of temperature and residence time on liquefaction of rice straw in subcritical CO2-subcritical water (subCO2-subH2O) and in subcritical CO2-supercritical ethanol (subCO2-scEtOH), considering the final reaction temperatures (270-345°C) and residence times (15 and 30min). Residence time was identified as a crucial parameter in the subCO2-subH2O liquefaction, whereas residence time had a marginal influence on subCO2-scEtOH liquefaction. When reaction conditions were 320°C and 15min, solvents have weak impact on the quality of bio-oil, HHV 28.57MJ/kg and 28.62MJ/kg, respectively. There was an obvious difference between the subCO2-subH2O and subCO2-scEtOH liquefaction mechanisms. In subCO2-subH2O, CO2 promoted the carbonyl reaction. In subCO2-scEtOH, supercritical ethanol have the function of donating hydrogen and promoting the reaction of hydroxyl-alkylation.

  14. SUPERCRITICAL FLUID EXTRACTION OF POLYCYCLIC AROMATIC HYDROCARBON MIXTURES FROM CONTAMINATED SOILS

    Science.gov (United States)

    Highly contaminated (with PAHs) topsoils were extracted with supercritical CO2 to determine the feasibility and mechanism of supercritical fluid extraction (SFE). Effect of SCF density, temperature, cosolvent type and amount, and of slurrying the soil with water were ...

  15. Investigation of parameter estimation and impact of injection rate on relative permeability measurements for supercritical CO2 and water by unsteady-state method

    Science.gov (United States)

    Hiratsuka, Y.; Yamamoto, H.

    2014-12-01

    CCS (Carbon dioxide Capture and Storage) is a promising option for mitigating climate changes. To predict the behavior of injected CO2 in a deep reservoir, relative permeability of supercritical CO2 and water of the reservoir rock is one of the most fundamental and influential properties. For determining the relative permeability, we employed the unsteady state method, in which the relative permeability is determined based on history matching of transient monitoring data with a multi-phase flow model. The unsteady-state method is relatively simple and short, but obviously its accuracy strongly depends on the flow model assumed in the history matching. In this study, we conducted relative permeability measurements of supercritical CO2-water system for Berea sandstone with the unsteady-state method under a reservoir condition at a 1km depth (P= 9.5MPa, T = 44˚C). Automatic history matching was performed with an inversion simulator iTOUGH2/ECO2N for multi-phase flow system of supercritical CO2, NaCl, and water. A sensitivity analysis of relative permeability parameters for CO2 and water was carried out to better understand the uniqueness and the uncertainty of the optimum solution estimated by the history matching. Among the parameters of the Corey-type curve employed in this study, while the end-point permeability could be optimized in a limited range, the other parameters were correlated and their combinations were not unique. However it was found that any combination of these parameters results in nearly identical shapes of the curve in the range of CO2 saturation in this study (0 to 60%). The optimally estimated curve from the unsteady-method was well comparable with those from the steady-state method acquired in the previous studies. Our experiment also focuses on the impact of injection rate on the estimates of relative permeability, as it is known that the injection rate could have a significant effect on fluid distribution such as viscous fingering with

  16. Analysis on Affecting Factors and Kinetics of Wastewater Treatment by Catalytic Supercritical Water Oxidation%废水处理催化超临界水氧化法影响因素及动力学分析

    Institute of Scientific and Technical Information of China (English)

    韦朝海; 王刚; 谢波

    2000-01-01

    Affecting factors and kinetics by catalytic supercritical water oxidation were summed up,and the importance of catalyst in the process of catalytic supercritical water oxidation was emphasised. In addition,general kinetic model for catalytic supercritical water oxidation was deduced. Kinetic parameters and reacting conditions of organic compounds including phenol ,acetic acid and pyridine are expounded. The performance of complex compounds by catalytic supercritical water oxidation was discussed based on the above results. All of which offers theoretical guidance for waste water treatment. In the end,some suggestions were proposed for scale-up and engineering utilization of catalytic supercritical water oxidation.%归纳了催化超临界水氧化法的影响因素并分析其相互间的关系,阐明催化剂作用的重要性。此外,论文还推导了反应体系普遍的动力学模型,分别分析了环状化合物、难降解中间产物及含氮化合物的动力学特征参数及反应条件的制约关系,在此基础上讨论复杂有机化合物废水的反应动力学行为,以期为实际废水处理提供理论指导。论文的最后对催化超临界水氧化法的工程开发与实际应用化问题提出了若干构想与建议。

  17. Feasibility Study of Supercritical Light Water Cooled Fast Reactors for Actinide Burning and Electric Power Production, Progress Report for Work Through September 2002, 4th Quarterly Report

    Energy Technology Data Exchange (ETDEWEB)

    Mac Donald, Philip Elsworth

    2002-09-01

    The use of light water at supercritical pressures as the coolant in a nuclear reactor offers the potential for considerable plant simplification and consequent capital and O&M cost reduction compared with current light water reactor (LWR) designs. Also, given the thermodynamic conditions of the coolant at the core outlet (i.e. temperature and pressure beyond the water critical point), very high thermal efficiencies of the power conversion cycle are possible (i.e. up to about 45%). Because no change of phase occurs in the core, the need for steam separators and dryers as well as for BWR-type re-circulation pumps is eliminated, which, for a given reactor power, results in a substantially shorter reactor vessel and smaller containment building than the current BWRs. Furthermore, in a direct cycle the steam generators are not needed. If no additional moderator is added to the fuel rod lattice, it is possible to attain fast neutron energy spectrum conditions in a supercritical water-cooled reactor (SCWR). This type of core can make use of either fertile or fertile-free fuel and retain a hard spectrum to effectively burn plutonium and minor actinides from LWR spent fuel while efficiently generating electricity. One can also add moderation and design a thermal spectrum SCWR. The Generation IV Roadmap effort has identified the thermal spectrum SCWR (followed by the fast spectrum SCWR) as one of the advanced concepts that should be developed for future use. Therefore, the work in this NERI project is addressing both types of SCWRs.

  18. Fixed Bed Adsorption of Drugs on Silica Aerogel from Supercritical Carbon Dioxide Solutions

    Directory of Open Access Journals (Sweden)

    Giuseppe Caputo

    2013-01-01

    Full Text Available Supercritical adsorption coupled with the high adsorption capacity of silica aerogel allows the preparation of a new kind of delivery systems of poor water soluble drugs. In order to overcome drawbacks of conventional techniques where the use of liquid solvents can cause the fracture of aerogel porous structure, in this work a new adsorption process of drugs from a supercritical mixture is proposed. Adsorption takes place from a fluid solution of the drug in supercritical CO2 and ethanol as cosolvent. A fixed bed adsorption plant has been developed to allow fast mixing of fluid phase and effective contact in the adsorption column. The use of ethanol as cosolvent allows to overcome the limitation of supercritical adsorption due to low solubility of many drugs in supercritical CO2. Adsorption isotherms were measured for one-model substance, nimesulide, at 40°C, and breakthrough curve was experimentally obtained. The drug loading of the drug into silica aerogel was up to 9 wt%. The drug composite was characterized using scanning electron microscopy, and release kinetics of the adsorbed drug were also evaluated by in vitro dissolution tests. The dissolution of nimesulide from loaded aerogel is much faster than dissolution of crystalline nimesulide. Around 80% of nimesulide dissolves from the aerogel within 6 minutes, whereas dissolving 80% of the crystalline drug takes about 90 min.

  19. Recovery of Minerals in Martian Soils Via Supercritical Fluid Extraction

    Science.gov (United States)

    Debelak, Kenneth A.; Roth, John A.

    2001-03-01

    We are investigating the use of supercritical fluids to extract mineral and/or carbonaceous material from Martian surface soils and its igneous crust. Two candidate supercritical fluids are carbon dioxide and water. The Martian atmosphere is composed mostly of carbon dioxide (approx. 95.3%) and could therefore provide an in-situ source of carbon dioxide. Water, although present in the Martian atmosphere at only approx. 0.03%, is also a candidate supercritical solvent. Previous work done with supercritical fluids has focused primarily on their solvating properties with organic compounds. Interestingly, the first work reported by Hannay and Hogarth at a meeting of the Royal Society of London in 1879 observed that increasing or decreasing the pressure caused several inorganic salts e.g., cobalt chloride, potassium iodide, and potassium bromide, to dissolve or precipitate in supercritical ethanol. In high-pressure boilers, silica, present in most boiler feed waters, is dissolved in supercritical steam and transported as dissolved silica to the turbine blades. As the pressure is reduced the silica precipitates onto the turbine blades eventually requiring the shutdown of the generator. In supercritical water oxidation processes for waste treatment, dissolved salts present a similar problem. The solubility of silicon dioxide (SiO2) in supercritical water is shown. The solubility curve has a shape characteristic of supercritical systems. At a high pressure (greater than 1750 atmospheres) increasing the temperature results in an increase in solubility of silica, while at low pressures, less than 400 atm., the solubility decreases as temperature increases. There are only a few studies in the literature where supercritical fluids are used in extractive metallurgy. Bolt modified the Mond process in which supercritical carbon monoxide was used to produce nickel carbonyl (Ni(CO)4). Tolley and Tester studied the solubility of titanium tetrachloride (TiCl4) in supercritical CO2

  20. Experiment Study of Supercritical Water Heat Transfer in Bundle%棒束内超临界水传热实验研究

    Institute of Scientific and Technical Information of China (English)

    李虹波; 赵萌; 顾汉洋; 卢冬华

    2015-01-01

    The heat transfer experiment of supercritical water in two bundles with different P/D has been performed on the supercritical water multipurpose test loop coconstructed by China General Nuclear Power Corporation and Shanghai Jiao Tong University.The experiment data were obtained.The temperature non-uniformity in circumference of the bundles and heat transfer enhancement caused by the grids were observed obviously.The experiment research results of thermal-hydraulic parameters on heat transfer of supercritical water show that the heat transfer coefficient decreases and the temperature non-uniformity in circumference is enhanced with the increase of heat flux.The heat transfer coefficient increases and the temperature non-uniformity in circumference decreases with the increase of mass flux.The heat transfer coefficient decreases with the increase of system pressure.The heat transfer in bundles is enhanced with the decrease of P/D.%在中国广核集团有限公司和上海交通大学共建的超临界水多功能实验装置上,针对两种不同节径比(P/D)的棒束通道开展了超临界水流动传热实验,获得了传热实验数据,观测到了通道内棒束间明显的周向温度不均匀现象和定位格架导致的传热强化现象。通过对各种热工水力参数的实验研究,得出超临界水流动传热结论:随热流密度的增加,传热系数逐渐减小,棒束壁温周向不均匀程度逐渐增加;随质量流速的增加,传热系数逐渐增大,棒束壁温周向不均匀程度逐渐减小;随压力的逐渐升高,传热系数少许降低;随P/D的减小,棒束通道内的传热明显增强。

  1. 超临界水通道内压降特性分析%Analysis of Pressure Drop Characteristic in Supercritical Water Channel

    Institute of Scientific and Technical Information of China (English)

    徐莉; 臧金光; 曾小康; 闫晓

    2014-01-01

    Supercritical water-colded reactor (SCWR) is one of the fourth generation nuclear energy systems with the supercritical water as the reactor coolant and moderator .The sharp variation of fluid property near the pseudo-critical point will have influence on the pressure drop characteristics of the flow channel .In this study ,the pressure drops due to gravity , acceleration and friction were investigated under supercritical conditions and some suggestions were provided as reference .The flow path integration effect in gravity pressure drop needed to be accounted for .The explicit PKN formula was obtained based on the implicit PKN form which could be applied into isothermal flow .The comparison of different frictional pressure drop correlations with CFD numerical simulation results was made ,and it is found that the Kirillov correlation is close to CFD calculation results .%超临界水冷堆是以超临界水作为冷却剂和慢化剂的第4代核能系统之一,超临界水在拟临界区附近剧烈的物性变化会给通道内的压降特性带来影响。本文分析了超临界条件下重力压降、加速压降和摩擦压降的特点,并对具体的计算方式提供了一些建议和参考:重力压降需考虑沿程的积分效应;基于隐式PKN公式得到了显式PKN公式,用于求解等温流动摩擦系数;采用CFD数值分析工具比较了超临界条件下不同摩擦关系式的异同,发现Kirillov公式与CFD计算结果较为接近。

  2. Risk analysis for a radiolysis gas detonation in an in-pile loop with supercritical water; Risiko einer Radiolysegasdetonation in einem aktiven Versuchskreislauf mit ueberkritischem Wasser

    Energy Technology Data Exchange (ETDEWEB)

    Zeiger, T.; Raque, M.; Kuznetsov, M.; Redlinger, R.; Schulenberg, T. [Karlsruher Institut fuer Technologie (KIT), Eggenstein-Leopoldshafen (Germany). Inst. fuer Kern- und Energietechnik (IKET)

    2012-11-01

    The SCWR (supercritical water reactor) -FQT project is a cooperation between European and Chinese partners aimed to test the fuel SCWR elements under reactor conditions. In the frame of this work the risk of radiolysis gas production in the active range of the test track was assessed. The radiolysis gas could accumulate in an emergency cooling system with stagnating coolant. The ignition of this radiolysis gas could cause pressure peaks that are able to damage the primary coolant circuit. Pressure increase and deformations in case of ignition of accumulated gas were investigated. As piping material the Ti stabilized austenitic steel 08Ch18N10T was assumed, the simulation was performed using the ANSYS code. The results show that pipes without significant wall thickness enhancement cannot withstand the radiolysis gas detonation.

  3. Fuel composition optimization in a 78-element fuel bundle for use in a pressure tube type supercritical water-cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hummel, D.W.; Novog, D.R. [McMaster Univ., Hamilton, Ontario (Canada)

    2012-07-01

    A 78-element fuel bundle containing a plutonium-thorium fuel mixture has been proposed for a Generation IV pressure tube type supercritical water-cooled reactor. In this work, using a lattice cell model created with the code DRAGON,the lattice pitch, fuel composition (fraction of PuO{sub 2} in ThO{sub 2}) and radial enrichment profile of the 78-element bundle is optimized using a merit function and a metaheuristic search algorithm.The merit function is designed such that the optimal fuel maximizes fuel utilization while minimizing peak element ratings and coolant void reactivity. A radial enrichment profile of 10 wt%, 11 wt% and 20 wt% PuO{sub 2} (inner to outer ring) with a lattice pitch of 25.0 cm was found to provide the optimal merit score based on the aforementioned criteria. (author)

  4. Hydrogen production from co-gasification of coal and biomass in supercritical water by continuous flow thermal-catalytic reaction system

    Institute of Scientific and Technical Information of China (English)

    YAN Qiuhui; GUO Liejin; LIANG Xing; ZHANG Ximin

    2007-01-01

    Hydrogen is a clean energy carrier.Converting abundant coal sources and green biomass energy into hydrogen effectively and without any pollution promotes environmental protection.The co-gasification performance of coal and a model compound of biomass,carboxymethylcellulose (CMC)in supercritical water (SCW),were investigated experimentally.The influences of temperature,pressure and concentration on hydrogen production from co-gasification of coal and CMC in SCW under the given conditions (20-25 MPa,650℃,15-30 s) are discussed in detail.The experimental results show that H2,CO2 and CH4 are the main gas products,and the molar fraction of hydrogen reaches in excess of 60%.The higher pressure and higher CMC content facilitate hydrogen production;production is decreased remarkably given a longer residence time.

  5. Thermodynamic modelling of supercritical water gasification: investigating the effect of biomass composition to aid in the selection of appropriate feedstock material.

    Science.gov (United States)

    Louw, Jeanne; Schwarz, Cara E; Knoetze, Johannes H; Burger, Andries J

    2014-12-01

    A process model developed in Aspen Plus®, was used for the thermodynamic modelling of supercritical water gasification (SCWG) using a wide variety of biomass materials as feedstock. The influence of the composition of the biomass material (in terms of carbon, hydrogen and oxygen content) on various performance indicators (such as gas yields, cold gas efficiency, calorific value of product gas and heat of reaction), were determined at various temperatures (600, 700 and 800°C) and biomass feed concentrations (5, 15 and 25wt.%). Generalised contour plots, based on the biomass composition, were developed for these performance indicators to provide the thermodynamic limits at various operating conditions. These plots can aid in the selection or screening of potential biomass materials and appropriate operating conditions for SCWG prior to conducting experimental work.

  6. Co-destruction of organic pollutants in municipal solid waste leachate and dioxins in fly ash under supercritical water using H2O2 as oxidant.

    Science.gov (United States)

    Zou, Daoan; Chi, Yong; Fu, Chao; Dong, Jun; Wang, Fei; Ni, Mingjiang

    2013-03-15

    Supercritical water oxidation (SCWO), with hydrogen peroxide as oxidant, is applied to the co-disposal of two distinct waste streams: municipal solid waste leachate and incineration fly ash. The chemical oxygen demand (COD) removal efficiency increases rapidly with rising temperature and excess oxygen. Rising residence time from 1 to 2 min has surprisingly little effect. The addition of fly ash accelerates COD conversion markedly and also polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, dioxins) in the original fly ash are efficiently destroyed. High-chlorinated PCDD/Fs are more likely to be destroyed than low-chlorinated PCDD/Fs, at all experimental conditions. In addition, PCDDs are much more reactive than PCDFs, since the PCDDs/PCDFs ratio declines from 0.17 to 0.12 as excess oxygen rises from 0% to 300%.

  7. Heat Transfer Phenomena of Supercritical Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Krau, Carmen Isabella; Kuhn, Dietmar; Schulenberg, Thomas [Forschungszentrum Karlsruhe, Institute for Nuclear and Energy Technologies, 76021 Karlsruhe (Germany)

    2008-07-01

    In concepts for supercritical water cooled reactors, the reactor core is cooled and moderated by water at supercritical pressures. The significant temperature dependence of the fluid properties of water requires an exact knowledge of the heat transfer mechanism to avoid fuel pin damages. Near the pseudo-critical point a deterioration of heat transfer might happen. Processes, that take place in this case, are not fully understood and are due to be examined systematically. In this paper a general overview on the properties of supercritical water is given, experimental observations of different authors will be reviewed in order to identify heat transfer phenomena and onset of occurrence. The conceptional design of a test rig to investigate heat transfer in the boundary layer will be discussed. Both, water and carbon dioxide, may serve as operating fluids. The loop, including instrumentation and safety devices, is shown and suitable measuring methods are described. (authors)

  8. Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment.

    Science.gov (United States)

    Xiu, Fu-Rong; Qi, Yingying; Zhang, Fu-Shen

    2015-07-01

    Precious metals are the most attractive resources in waste printed circuit boards (PCBs) of mobile phones. In this work, an alternative process for recovering Au, Ag, and Pd from waste PCBs of mobile phones by supercritical water oxidation (SCWO) pre-treatment combined with iodine-iodide leaching process was developed. In the process, the waste PCBs of mobile phones were pre-treated in supercritical water, then a diluted hydrochloric acid leaching (HL) process was used to recovery the Cu, whose leaching efficiency was approximately 100%, finally the resulting residue was subjected to the iodine-iodide leaching process for recovering the Au, Ag, and Pd. Experimental results indicated that SCWO pre-treatment temperature, time, and pressure had significant influence on the Au, Ag, and Pd leaching from (SCWO+HL)-treated waste PCBs. The optimal SCWO pre-treatment conditions were 420°C and 60min for Au and Pd, and 410°C and 30min for Ag. The optimum dissolution parameters for Au, Pd, and Ag in (SCWO+HL)-treated PCBs with iodine-iodide system were leaching time of 120min (90min for Ag), iodine/iodide mole ratio of 1:5 (1:6 for Ag), solid-to-liquid ratio (S/L) of 1:10g/mL (1:8g/mL for Ag), and pH of 9, respectively. It is believed that the process developed in this study is environment friendly for the recovery of Au, Ag, and Pd from waste PCBs of mobile phones by SCWO pre-treatment combined with iodine-iodide leaching process.

  9. Liposomes Size Engineering by Combination of Ethanol Injection and Supercritical Processing.

    Science.gov (United States)

    Santo, Islane Espirito; Campardelli, Roberta; Albuquerque, Elaine Cabral; Vieira De Melo, Silvio A B; Reverchon, Ernesto; Della Porta, Giovanna

    2015-11-01

    Supercritical fluid extraction using a high-pressure packed tower is proposed not only to remove the ethanol residue from liposome suspensions but also to affect their size and distribution leading the production of nanosomes. Different operating pressures, temperatures, and gas to liquid ratios were explored and ethanol was successfully extracted up to a value of 400 ppm; liposome size and distribution were also reduced by the supercritical processing preserving their integrity, as confirmed by Z-potential data and Trasmission Electron Microscopy observations. Operating at 120 bar and 38°C, nanosomes with a mean diameter of about 180 ± 40 nm and good storage stability were obtained. The supercritical processing did not interfere on drug encapsulation, and no loss of entrapped drug was observed when the water-soluble fluorescein was loaded as a model compound. Fluorescein encapsulation efficiency was 30% if pure water was used during the supercritical extraction as processing fluid; whereas an encapsulation efficiency of 90% was obtained if the liposome suspension was processed in water/fluorescein solution. The described technology is easy to scale up to an industrial production and merge in one step the solvent extraction, liposome size engineering, and an excellent drug encapsulation in a single operation unit.

  10. 升温升压过程对聚丙烯在超临界水中降解的影响%Effect of Increasing Course of Temperature and Pressure on Polypropylene Degradation in Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    苏磊; 吴学华; 刘秀茹; 陈丽英; 陈克宇; 洪时明

    2007-01-01

    The effect of increasing course of temperature and pressure on polypropylene (PP) degradation in supercritical water was investigated for developing a process of recycling waste plastic. A group of experiments was carried out in a reaction system at a pressure of 26MPa, temperature of 380℃ or 400℃ for 30min, 70min, and 120main by Course One (the increasing course of temperature and pressure is via gaseous regions to supercritical regions), and the other group was carried out at corresponding holding conditions by Course Two (the increasing course of temperature and pressure is via liquid regions to supercritical regions). The time of the increasing courses was about 30min. Products were analyzed by Ostward-type viscometer, gaseous chromatography, and mass spectrometers (GC/MS). Characterization results suggested that different increasing courses of temperature and pressure would give rise to different results, although they were treated under the similar holding conditions. It was also found that Course Two was more effective on PP degradation in supercritical water.

  11. An application of the novel quantum mechanical/molecular mechanical method combined with the theory of energy representation: An ionic dissociation of a water molecule in the supercritical water.

    Science.gov (United States)

    Takahashi, Hideaki; Satou, Wataru; Hori, Takumi; Nitta, Tomoshige

    2005-01-22

    A novel quantum chemical approach recently developed has been applied to an ionic dissociation of a water molecule (2H(2)O-->H(3)O(+)+OH(-)) in ambient and supercritical water. The method is based on the quantum mechanical/molecular mechanical (QM/MM) simulations combined with the theory of energy representation (QM/MM-ER), where the energy distribution function of MM solvent molecules around a QM solute serves as a fundamental variable to determine the hydration free energy of the solute according to the rigorous framework of the theory of energy representation. The density dependence of the dissociation free energy in the supercritical water has been investigated for the density range from 0.1 to 0.6 g/cm(3) with the temperature fixed at a constant. It has been found that the product ionic species significantly stabilizes in the high density region as compared with the low density. Consequently, the dissociation free energy decreases monotonically as the density increases. The decomposition of the hydration free energy has revealed that the entropic term (-TDeltaS) strongly depends on the density of the solution and dominates the behavior of the dissociation free energy with respect to the variation of the density. The increase in the entropic term in the low density region can be attributed to the decrease in the translational degrees of freedom brought about by the aggregation of solvent water molecules around the ionic solute.

  12. Electron bombardment of water adsorbed on Zr(0001) surfaces

    CERN Document Server

    Ankrah, S; Ramsier, R D

    2003-01-01

    A study of the effects of electron bombardment on water adsorbed on Zr(0001) is reported. Zirconium surfaces are dosed with isotopic water mixtures at 160 K followed by electron bombardment (485 eV). The system is then probed by low energy electron diffraction, temperature programmed desorption (TPD) and Auger electron spectroscopy (AES). No evidence is found that would indicate preferential mixing of hydrogen from the bulk with isotopic water dissociation products during TPD. However, electron bombardment results in the sharpening of a hydrogen/deuterium desorption peak near 320 K and the production of water near 730 K at low water exposures. In addition, although water does not oxidize Zr(0001) thermally, electron bombardment of adsorbed water induces a shift of about 2 eV in the Zr AES features indicating that the surface is partially oxidized by electron bombardment.

  13. Supercritical fluid extraction

    Science.gov (United States)

    Wai, Chien M.; Laintz, Kenneth

    1994-01-01

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated or lipophilic crown ether or fluorinated dithiocarbamate. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

  14. Reactive turbulent flow CFD study in supercritical water oxidation process: application to a stirred double shell reactor; Etude par simulation numerique des ecoulements turbulents reactifs dans les reacteurs d'oxydation hydrothermale: application a un reacteur agite double enveloppe

    Energy Technology Data Exchange (ETDEWEB)

    Moussiere, S

    2006-12-15

    Supercritical water oxidation is an innovative process to treat organic liquid waste which uses supercritical water properties to mix efficiency the oxidant and the organic compounds. The reactor is a stirred double shell reactor. In the step of adaptation to nuclear constraints, the computational fluid dynamic modeling is a good tool to know required temperature field in the reactor for safety analysis. Firstly, the CFD modeling of tubular reactor confirms the hypothesis of an incompressible fluid and the use of k-w turbulence model to represent the hydrodynamic. Moreover, the EDC model is as efficiency as the kinetic to compute the reaction rate in this reactor. Secondly, the study of turbulent flow in the double shell reactor confirms the use of 2D axisymmetric geometry instead of 3D geometry to compute heat transfer. Moreover, this study reports that water-air mixing is not in single phase. The reactive turbulent flow is well represented by EDC model after adaptation of initial conditions. The reaction rate in supercritical water oxidation reactor is mainly controlled by the mixing. (author)

  15. 超临界水中添加过氧化苯甲酰对聚丙烯降解的促进作用%An Investigation on Polypropylene Degradation in Supercritical Water Adding Benzoyl Peroxide

    Institute of Scientific and Technical Information of China (English)

    苏磊; 吴学华; 刘秀茹; 陈丽英; 陈克宇; 洪时明

    2005-01-01

    The effect of benzoyl peroxide (BPO) on polypropylene (PP) degradation in supercritical water was investigated with the aim of developing a process for recycling of waste plastics. A series of experiments with and without BPO were carried out at temperatures of 653K and 673K under pressure about 26 MPa for 30, 75 and 120 min respectively. Products were analyzed by an Ostward-type viscometer, gas chromatography and spectrometry (GC/MS) etc. The results indicated that mean molecular weight of the samples decreased greatly along with the time elapsing or with the temperature increasing, and PP was decomposed to aliphatic and cycloparaffinic hydrocarbons but a few benzenoid hydrocarbons. By comparing the experiments with and without BPO, it was made clear that BPO is an effective additive on PP degradation in supercritical water.

  16. Analytical method development for the determination of emerging contaminants in water using supercritical-fluid chromatography coupled with diode-array detection.

    Science.gov (United States)

    Del Carmen Salvatierra-Stamp, Vilma; Ceballos-Magaña, Silvia G; Gonzalez, Jorge; Ibarra-Galván, Valentin; Muñiz-Valencia, Roberto

    2015-05-01

    An analytical method using supercritical-fluid chromatography coupled with diode-array detection for the determination of seven emerging contaminants-two pharmaceuticals (carbamazepine and glyburide), three endocrine disruptors (17α-ethinyl estradiol, bisphenol A, and 17β-estradiol), one bactericide (triclosan), and one pesticide (diuron)-was developed and validated. These contaminants were chosen because of their frequency of use and their toxic effects on both humans and the environment. The optimized chromatographic separation on a Viridis BEH 2-EP column achieved baseline resolution for all compounds in less than 10 min. This separation was applied to environmental water samples after sample preparation. The optimized sample treatment involved a preconcentration step by means of solid-phase extraction using C18-OH cartridges. The proposed method was validated, finding recoveries higher than 94 % and limits of detection and limits of quantification in the range of 0.10-1.59 μg L(-1) and 0.31-4.83 μg L(-1), respectively. Method validation established the proposed method to be selective, linear, accurate, and precise. Finally, the method was successfully applied to environmental water samples.

  17. Development of a Novel Milling System Using Supercritical Carbon Dioxide for Improvement of Dissolution Characteristics of Water-Poorly Soluble Drugs.

    Science.gov (United States)

    Fern, Jennifer Chia Wee; Nakamura, Hideya; Watano, Satoru

    2016-01-01

    The aim of this study is to develop a novel milling system using supercritical carbon dioxide (SC-CO2) for the improvement of dissolution characteristics of water-poorly soluble drugs. SC-CO2 possesses high potential in the application of nanotechnology, due to the attractive properties of SC-CO2 fluid such as cheap, inert and non-polluting. In addition, SC-CO2 has density comparable to a liquid, viscosity similar to a gas, and high diffusion capacity. Most of all, carbon dioxide exists as gas in room temperature and pressure, which enables the removal of fluid instantaneously. In this study, a novel method of milling using SC-CO2 was proposed to produce fine-drug particles. SC-CO2 milling was conducted and its performance was compared with the ones by various milling methods such as jet milling, dry milling and wet milling. A comparison on the effect of each milling medium on its milling performance, drug size distribution, and particle morphology was conducted. Operating variables of the SC-CO2 milling system were also investigated to clarify the factors affecting the milling properties and to improve drug release characteristics of water-poorly soluble drugs.

  18. Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment

    Energy Technology Data Exchange (ETDEWEB)

    Xiu, Fu-Rong, E-mail: xiu_chem@hotmail.com [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350108 (China); Qi, Yingying [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350108 (China); Zhang, Fu-Shen [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2015-07-15

    Highlights: • We report a novel process for recovering Au, Ag, and Pd from waste PCBs. • The effect of SCWO on the leaching of Au, Ag, and Pd in waste PCBs was studied. • SCWO was highly efficient for enhancing the leaching of Au, Ag, and Pd. • The optimum leaching parameters for Au, Ag, and Pd in iodine–iodide were studied. - Abstract: Precious metals are the most attractive resources in waste printed circuit boards (PCBs) of mobile phones. In this work, an alternative process for recovering Au, Ag, and Pd from waste PCBs of mobile phones by supercritical water oxidation (SCWO) pre-treatment combined with iodine–iodide leaching process was developed. In the process, the waste PCBs of mobile phones were pre-treated in supercritical water, then a diluted hydrochloric acid leaching (HL) process was used to recovery the Cu, whose leaching efficiency was approximately 100%, finally the resulting residue was subjected to the iodine–iodide leaching process for recovering the Au, Ag, and Pd. Experimental results indicated that SCWO pre-treatment temperature, time, and pressure had significant influence on the Au, Ag, and Pd leaching from (SCWO + HL)-treated waste PCBs. The optimal SCWO pre-treatment conditions were 420 °C and 60 min for Au and Pd, and 410 °C and 30 min for Ag. The optimum dissolution parameters for Au, Pd, and Ag in (SCWO + HL)-treated PCBs with iodine–iodide system were leaching time of 120 min (90 min for Ag), iodine/iodide mole ratio of 1:5 (1:6 for Ag), solid-to-liquid ratio (S/L) of 1:10 g/mL (1:8 g/mL for Ag), and pH of 9, respectively. It is believed that the process developed in this study is environment friendly for the recovery of Au, Ag, and Pd from waste PCBs of mobile phones by SCWO pre-treatment combined with iodine–iodide leaching process.

  19. Corrosion in Supercritical carbon Dioxide: Materials, Environmental Purity, Surface Treatments, and Flow Issues

    Energy Technology Data Exchange (ETDEWEB)

    Sridharan, Kumar; Anderson, Mark

    2013-12-10

    separately to high purity CO{sub 2}. Task 3: Evaluation of surface treatments on the corrosion performance of alloys in supercritical CO{sub 2}: Surface treatments can be very beneficial in improving corrosion resistance. Shot peening and yttrium and aluminum surface treatments will be investigated. Shot peening refines the surface grain sizes and promotes protective Cr-oxide layer formation. Both yttrium and aluminum form highly stable oxide layers (Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3}), which can get incorporated in the growing Fe-oxide layer to form an impervious complex oxide to enhance corrosion resistance. Task 4: Study of flow-assisted corrosion of select alloys in supercritical CO{sub 2} under a selected set of test conditions: To study the effects of flow-assisted corrosion, tests will be conducted in a supercritical CO{sub 2} flow loop. An existing facility used for supercritical water flow studies at the proposing university will be modified for use in this task. The system is capable of flow velocities up to 10 m/s and can operate at temperatures and pressures of up to 650°C and 20 MPa, respectively. All above tasks will be performed in conjunction with detailed materials characterization and analysis using scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS), x-ray diffraction (XRD), Auger electron spectroscopy (AES) techniques, and weight change measurements. Inlet and outlet gas compositions will be monitored using gas chromatography-mass spectrometry (GCMS).

  20. Thermodynamic Optimization of Supercritical CO{sub 2} Brayton Cycles

    Energy Technology Data Exchange (ETDEWEB)

    Rhim, Dong-Ryul; Park, Sung-Ho; Kim, Su-Hyun; Yeom, Choong-Sub [Institute for Advanced Engineering, Yongin (Korea, Republic of)

    2015-05-15

    The supercritical CO{sub 2} Brayton cycle has been studied for nuclear applications, mainly for one of the alternative power conversion systems of the sodium cooled fast reactor, since 1960's. Although the supercritical CO{sub 2} Brayton cycle has not been expected to show higher efficiency at lower turbine inlet temperature over the conventional steam Rankine cycle, the higher density of supercritical CO{sub 2} like a liquid in the supercritical region could reduce turbo-machinery sizes, and the potential problem of sodium-water reaction with the sodium cooled fast reactor might be solved with the use of CO{sub 2} instead of water. The supercritical CO{sub 2} recompression Brayton cycle was proposed for the better thermodynamic efficiency than for the simple supercritical CO{sub 2} Brayton cycle. Thus this paper presents the efficiencies of the supercritical CO{sub 2} recompression Brayton cycle along with several decision variables for the thermodynamic optimization of the supercritical CO{sub 2} recompression Brayton cycle. The analytic results in this study show that the system efficiency reaches its maximum value at a compressor outlet pressure of 200 bars and a recycle fraction of 30 %, and the lower minimum temperature approach at the two heat exchangers shows higher system efficiency as expected.

  1. Comparison of T-piece and concentric mixing systems for continuous flow synthesis of anatase nanoparticles in supercritical isopropanol/water

    Science.gov (United States)

    Toft, Lars L.; Aarup, David F.; Bremholm, Martin; Hald, Peter; Iversen, Bo B.

    2009-03-01

    T-piece and concentric counter-flow mixing systems are compared in continuous flow supercritical solvothermal synthesis of TiO 2 at identical system parameters. The phase pure anatase nanoparticle products were characterized with powder X-ray diffraction (PXRD), transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS), and the particle size, size distribution and absolute crystallinity mapped as a function of temperature, precursor concentration, flow rate and pressure for the two different continuous flow reactors. The particles synthesized with the T-piece geometry are smaller with a narrower size distribution, possibly indicating a more effective mixing, than particles synthesized at the same conditions with concentric counter-flow geometry. In general, an increased synthesis temperature leads to an increase in absolute crystallinity. For the particles synthesized with the concentric reactor geometry crossing of the critical point of the solvent causes a decrease in the particle size and size distribution, and conditions just above the critical temperature are demonstrated to be optimal for continuous solvothermal synthesis of anatase.

  2. Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method.

    Science.gov (United States)

    Kalani, Mahshid; Yunus, Robiah

    2012-01-01

    The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks.

  3. Reactivity of Forsterite, Lizardite, and Antigorite in Dry to Water-Saturated Supercritical CO2 - An In Situ Infrared Spectroscopic Investigation

    Science.gov (United States)

    Loring, J. S.; Thompson, C. J.; Wang, Z.; Schaef, H. T.; Felmy, A. R.; Rosso, K. M.

    2010-12-01

    Geologic carbon sequestration (GCS) is a promising technology for reducing anthropogenic emissions of CO2 into the atmosphere. Olivines and serpentines are potentially important mineral phases in GCS because they are widespread in basalt formations and caprocks, are rich in Ca, Mg, and Fe, and react exothermically with CO2 to form carbonate solids. Previous work in aqueous systems has shown that carbonation rates of serpentines are lower than those of olivines, unless heat or acid pretreatments are applied. To the best of our knowledge, the comparative reactivities of olivines and serpentines have not yet been explored in dry to water saturated supercritical CO2 (scCO2) under conditions relevant to geologic sequestration. In this study, we used in situ infrared spectroscopy to investigate the carbonation of forsterite (Mg2SiO4), a representative of the olivine group and two serpentine polymorphs, antigorite and lizardite (Mg3Si2O5(OH)4). Experiments were carried out at 35 °C and 100 bar using a flow-through system equipped with a high-pressure mid-infrared cell. One ZnSe window of the transmission cell was coated with a thin overlayer of the mineral under investigation. Absorbance spectra were recorded as a function of time for 24 hours after exposing the overlayer to scCO2 containing water at concentrations corresponding to 0%, 50% and 95% saturation. Experiments were also performed with an approximately 2-fold excess concentration of water. In these latter experiments, a controlled temperature gradient was used to intentionally condense a liquid water film on the mineral surfaces. Little reaction was observed for the minerals exposed to dry scCO2. At water concentrations of 50% and 95% saturation, a very thin, liquid-like water film was detected on the mineral surface. A relatively minor extent of reaction occurred, and most of the transformation was observed during the first three hours of the experiments. Much greater reactivity was evident when a thicker

  4. Evidence for very tight sequestration of BTEX compounds in manufactured gas plant soils based on selective supercritical fluid extraction and soil/water partitioning.

    Science.gov (United States)

    Hawthorne, Steven B; Miller, David J

    2003-08-15

    Benzene, toluene, ethylbenzene, o-, m-, and p-xylenes (BTEX), and polycyclic aromatic hydrocarbons (PAHs) were extracted from eight manufactured gas plant (MGP) soils from sites that had been abandoned for several decades. Supercritical fluid extraction (SFE) with pure carbon dioxide demonstrated the presence of BTEX compounds that were highly sequestered in both coal gas and oil gas MGP soils and soots. Benzene was generally the slowest compound to extract from all samples and was even more difficult to extract than most two- to five-ring PAHs found on the same samples. Since the solubility of benzene in carbon dioxide is 2-5 orders of magnitude higher than the solubilities of PAHs, these results demonstrate that benzene was more tightly sequestered than toluene, ethylbenzene, xylenes, or the multi-ring PAHs. Additional evidence for very tight binding was based on the fact that BTEX concentrations determined using either SFE or with methylene chloride sonication were much higher than those obtained by the U.S. EPA purge-and-trap method, especially for benzene (whose concentration was underestimated by as much as 1000-fold by the EPA method). However, soil/water desorption showed little benzene mobility, and Kd values for benzene were 1-2 orders of magnitude higher than those calculated based on literature sorption K(OC) values. These results indicate that environmentally relevant concentrations of benzene may be better represented by mild extraction methods than by methods capable of extracting tightly bound benzene.

  5. Evolution of strategies to achieve baseline separation of ten anionic, water-soluble sulfated estrogens via achiral packed column supercritical fluid chromatography.

    Science.gov (United States)

    Patel, M A; Hardink, M A; Wrisely, L; Riley, F W; Hudalla, C J; Ashraf-Khorassani, M; Taylor, L T

    2014-11-28

    Near baseline separation of ten sulfated sodium salts of various structurally related estrogens employing a variety of bonded stationary phase packed columns was obtained using a conventional supercritical fluid chromatograph coupled with UV detection. Critical pairs 2/3 (8,9-dehydroestrone/17β-dihydroequilin) and 6/7 (17α-estradiol or 17α-dihydroequilin/estrone), however, failed to baseline separate. In all preliminary separations, 10mM ammonium acetate and variable percentages of H2O were initially used as co-additives in conjunction with methanol as a modifier. Different modifier programs and temperatures were employed to optimize the separation in a timely manner. A 2-ethylpyridine column provided the best separation compared to bare silica, diol, and cyano-based bonded phase columns. The employment of both salt and water as additives to the methanol-modified CO2 mobile phase suggested a mixed mode separation mechanism involving both ion pairing of each anionic sulfated estrogen with ammonium ion and hydrophilic interaction facilitated by partitioning of analyte between the aqueous solvated stationary phase and the aqueous component of the mobile phase. Upon more extensive study with either iso-propylamine or formic acid-ammonium formate buffer, the critical anionic pairs were 95% baseline resolved.

  6. Electrochemistry in supercritical fluids

    Science.gov (United States)

    Branch, Jack A.; Bartlett, Philip N.

    2015-01-01

    A wide range of supercritical fluids (SCFs) have been studied as solvents for electrochemistry with carbon dioxide and hydrofluorocarbons (HFCs) being the most extensively studied. Recent advances have shown that it is possible to get well-resolved voltammetry in SCFs by suitable choice of the conditions and the electrolyte. In this review, we discuss the voltammetry obtained in these systems, studies of the double-layer capacitance, work on the electrodeposition of metals into high aspect ratio nanopores and the use of metallocenes as redox probes and standards in both supercritical carbon dioxide–acetonitrile and supercritical HFCs. PMID:26574527

  7. Electrochemistry in supercritical fluids.

    Science.gov (United States)

    Branch, Jack A; Bartlett, Philip N

    2015-12-28

    A wide range of supercritical fluids (SCFs) have been studied as solvents for electrochemistry with carbon dioxide and hydrofluorocarbons (HFCs) being the most extensively studied. Recent advances have shown that it is possible to get well-resolved voltammetry in SCFs by suitable choice of the conditions and the electrolyte. In this review, we discuss the voltammetry obtained in these systems, studies of the double-layer capacitance, work on the electrodeposition of metals into high aspect ratio nanopores and the use of metallocenes as redox probes and standards in both supercritical carbon dioxide-acetonitrile and supercritical HFCs.

  8. Supercritical Fluid Chromatography, Pressurized Liquid Extraction and Supercritical Fluid Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Matthew C.; Yonker, Clement R.

    2006-06-15

    are regulated as food supplements but are intended to treat disease or maintain health. Antioxidants and beneficial lipid products are major examples in this category. The final major category consists of environmental applications, both as an extraction technique for environmental analysis, and as a possible remediation strategy for removing contaminants that would otherwise be too expensive to recover. Most of the work in this area has focused on non-polar compounds, such as polyaromatic hydrocarbons (PAHs) and poly-chlorinated biphenyls (PCB’s), where non-polar supercritical (SC) CO2 offers high extraction efficiencies. Co-solvent systems combining CO2 with one or more modifiers extend the utility of SC CO2 to polar and even ionic compounds. Supercritical water can extract polar compounds, and it has the additional advantage of combining extraction and destruction of contaminants via the supercritical water oxidation (SUWOX) process. Supercritical fluids are also useful in various niche applications. Fuel extraction, conversion, and analysis is one such application. Extraction of metals from various matrixes is also an area of continuing interest. The application of supercritical fluid (SCF) technology to production of nano-structured materials is a new area likely to see rapid growth in the next few years.

  9. Introduction to supercritical fluids a spreadsheet-based approach

    CERN Document Server

    Smith, Richard; Peters, Cor

    2013-01-01

    This text provides an introduction to supercritical fluids with easy-to-use Excel spreadsheets suitable for both specialized-discipline (chemistry or chemical engineering student) and mixed-discipline (engineering/economic student) classes. Each chapter contains worked examples, tip boxes and end-of-the-chapter problems and projects. Part I covers web-based chemical information resources, applications and simplified theory presented in a way that allows students of all disciplines to delve into the properties of supercritical fluids and to design energy, extraction and materials formation systems for real-world processes that use supercritical water or supercritical carbon dioxide. Part II takes a practical approach and addresses the thermodynamic framework, equations of state, fluid phase equilibria, heat and mass transfer, chemical equilibria and reaction kinetics of supercritical fluids. Spreadsheets are arranged as Visual Basic for Applications (VBA) functions and macros that are completely (source code) ...

  10. Measurement of Orotic Acid in Urine by Supercritical Fluid Chromatography

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This work presents a simple, rapid and reliable supercritical fluid chromatography (SFC) method for a sensitive measurement of orotic acid in human urine. The samples were diluted with deionized water and analyzed directly without any pretreatment.

  11. Supercritical Airfoil Coordinates

    Data.gov (United States)

    National Aeronautics and Space Administration — Rectangular Supercritical Wing (Ricketts) - design and measured locations are provided in an Excel file RSW_airfoil_coordinates_ricketts.xls . One sheet is with Non...

  12. Modeling the radiolysis of supercritical water by fast neutrons: density dependence of the yields of primary species at 400°c.

    Science.gov (United States)

    Butarbutar, Sofia Loren; Meesungnoen, Jintana; Guzonas, David A; Stuart, Craig R; Jay-Gerin, Jean-Paul

    2014-12-01

    A reliable understanding of radiolysis processes in supercritical water (SCW)-cooled reactors is crucial to developing chemistry control strategies that minimize the corrosion and degradation of materials. However, directly measuring the chemistry in reactor cores is difficult due to the extreme conditions of high temperature and pressure and mixed neutron and gamma-radiation fields, which are incompatible with normal chemical instrumentation. Thus, chemical models and computer simulations are an important route of investigation for predicting the detailed radiation chemistry of the coolant in a SCW reactor and the consequences for materials. Surprisingly, information on the fast neutron radiolysis of water at high temperatures is limited, and even more so for fast neutron irradiation of SCW. In this work, Monte Carlo simulations were used to predict the G values for the primary species e(-)aq, H(•), H2, (•)OH and H2O2 formed from the radiolysis of pure, deaerated SCW (H2O) by 2 MeV monoenergetic neutrons at 400°C as a function of water density in the range of ∼0.15-0.6 g/cm(3). The 2 MeV neutron was taken as representative of a fast neutron flux in a reactor. For light water, the moderation of these neutrons after knock-on collisions with water molecules generated mostly recoil protons of 1.264, 0.465, 0.171 and 0.063 MeV. Neglecting oxygen ion recoils and assuming that the most significant contribution to the radiolysis came from these first four recoil protons, the fast neutron yields were estimated as the sum of the G values for these protons after appropriate weightings were applied according to their energy. Calculated yields were compared with available experimental data and with data obtained for low-LET radiation. Most interestingly, the reaction of H(•) atoms with water was found to play a critical role in the formation yields of H2 and (•)OH at 400°C. Recent work has underscored the potential importance of this reaction above 200°C, but its

  13. Advanced Supercritical Carbon Dioxide Brayton Cycle Development

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Mark [Univ. of Wisconsin, Madison, WI (United States); Sienicki, James [Argonne National Lab. (ANL), Argonne, IL (United States); Moisseytsev, Anton [Argonne National Lab. (ANL), Argonne, IL (United States); Nellis, Gregory [Univ. of Wisconsin, Madison, WI (United States); Klein, Sanford [Univ. of Wisconsin, Madison, WI (United States)

    2015-10-21

    Fluids operating in the supercritical state have promising characteristics for future high efficiency power cycles. In order to develop power cycles using supercritical fluids, it is necessary to understand the flow characteristics of fluids under both supercritical and two-phase conditions. In this study, a Computational Fluid Dynamic (CFD) methodology was developed for supercritical fluids flowing through complex geometries. A real fluid property module was implemented to provide properties for different supercritical fluids. However, in each simulation case, there is only one species of fluid. As a result, the fluid property module provides properties for either supercritical CO2 (S-CO2) or supercritical water (SCW). The Homogeneous Equilibrium Model (HEM) was employed to model the two-phase flow. HEM assumes two phases have same velocity, pressure, and temperature, making it only applicable for the dilute dispersed two-phase flow situation. Three example geometries, including orifices, labyrinth seals, and valves, were used to validate this methodology with experimental data. For the first geometry, S-CO2 and SCW flowing through orifices were simulated and compared with experimental data. The maximum difference between the mass flow rate predictions and experimental measurements is less than 5%. This is a significant improvement as previous works can only guarantee 10% error. In this research, several efforts were made to help this improvement. First, an accurate real fluid module was used to provide properties. Second, the upstream condition was determined by pressure and density, which determines supercritical states more precise than using pressure and temperature. For the second geometry, the flow through labyrinth seals was studied. After a successful validation, parametric studies were performed to study geometric effects on the leakage rate. Based on these parametric studies, an optimum design strategy for the see

  14. Metal Nanoparticles Preparation In Supercritical Carbon Dioxide Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Harry W. Rollins

    2004-04-01

    The novel optical, electronic, and/or magnetic properties of metal and semiconductor nanoparticles have resulted in extensive research on new methods for their preparation. An ideal preparation method would allow the particle size, size distribution, crystallinity, and particle shape to be easily controlled, and would be applicable to a wide variety of material systems. Numerous preparation methods have been reported, each with its inherent advantages and disadvantages; however, an ideal method has yet to emerge. The most widely applied methods for nanoparticle preparation include the sonochemical reduction of organometallic reagents,(1&2) the solvothermal method of Alivisatos,(3) reactions in microemulsions,(4-6) the polyol method (reduction by alcohols),(7-9) and the use of polymer and solgel materials as hosts.(10-13) In addition to these methods, there are a variety of methods that take advantage of the unique properties of a supercritical fluid.(14&15) Through simple variations of temperature and pressure, the properties of a supercritical fluid can be continuously tuned from gas-like to liquid-like without undergoing a phase change. Nanoparticle preparation methods that utilize supercritical fluids are briefly reviewed below using the following categories: Rapid Expansion of Supercritical Solutions (RESS), Reactive Supercritical Fluid Processing, and Supercritical Fluid Microemulsions. Because of its easily accessible critical temperature and pressure and environmentally benign nature, carbon dioxide is the most widely used supercritical solvent. Supercritical CO2 is unfortunately a poor solvent for many polar or ionic species, which has impeded its use in the preparation of metal and semiconductor nanoparticles. We have developed a reactive supercritical fluid processing method using supercritical carbon dioxide for the preparation of metal and metal sulfide particles and used it to prepare narrowly distributed nanoparticles of silver (Ag) and silver sulfide

  15. In Situ Infrared Spectroscopic Study of Brucite Carbonation in Dry to Water-Saturated Supercritical Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Loring, John S.; Thompson, Christopher J.; Zhang, Changyong; Wang, Zheming; Schaef, Herbert T.; Rosso, Kevin M.

    2012-04-25

    In geologic carbon sequestration, while part of the injected carbon dioxide will dissolve into host brine, some will remain as neat to water saturated super critical CO2 (scCO2) near the well bore and at the caprock, especially in the short-term life cycle of the sequestration site. Little is known about the reactivity of minerals with scCO2 containing variable concentrations of water. In this study, we used high-pressure infrared spectroscopy to examine the carbonation of brucite (Mg(OH)2) in situ over a 24 hr reaction period with scCO2 containing water concentrations between 0% and 100% saturation, at temperatures of 35, 50, and 70 °C, and at a pressure of 100 bar. Little or no detectable carbonation was observed when brucite was reacted with neat scCO2. Higher water concentrations and higher temperatures led to greater brucite carbonation rates and larger extents of conversion to magnesium carbonate products. The only observed carbonation product at 35 °C was nesquehonite (MgCO3 • 3H2O). Mixtures of nesquehonite and magnesite (MgCO3) were detected at 50 °C, but magnesite was more prevalent with increasing water concentration. Both an amorphous hydrated magnesium carbonate solid and magnesite were detected at 70 °C, but magnesite predominated with increasing water concentration. The identity of the magnesium carbonate products appears strongly linked to magnesium water exchange kinetics through temperature and water availability effects.

  16. Towards Overhauser DNP in supercritical CO2

    Science.gov (United States)

    van Meerten, S. G. J.; Tayler, M. C. D.; Kentgens, A. P. M.; van Bentum, P. J. M.

    2016-06-01

    Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for 1H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in 1H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4 ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4 T on high pressure superheated water and model systems such as toluene in high pressure CO2.

  17. Towards Overhauser DNP in supercritical CO2.

    Science.gov (United States)

    van Meerten, S G J; Tayler, M C D; Kentgens, A P M; van Bentum, P J M

    2016-06-01

    Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for (1)H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in (1)H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4T on high pressure superheated water and model systems such as toluene in high pressure CO2.

  18. Fused silica capillaries with two segments of different internal diameters and inner surface roughnesses prepared by etching with supercritical water and used for volume coupling electrophoresis.

    Science.gov (United States)

    Horká, Marie; Karásek, Pavel; Roth, Michal; Šlais, Karel

    2017-02-22

    In this work, single-piece fused silica capillaries with two different internal diameter segments featuring different inner surface roughness were prepared by new etching technology with supercritical water and used for volume coupling electrophoresis. The concept of separation and online pre-concentration of analytes in high conductivity matrix is based on the online large-volume sample pre-concentration by the combination of transient isotachophoretic stacking and sweeping of charged proteins in micellar electrokinetic chromatography using non-ionogenic surfactant. The modified surface roughness step helped to the significant narrowing of the zones of examined analytes. The sweeping and separating steps were accomplished simultaneously by the use of phosphate buffer (pH 7) containing ethanol, non-ionogenic surfactant Brij 35, and polyethylene glycol (PEG 10000) after sample injection. Sample solution of a large volume (maximum 3.7 μL) dissolved in physiological saline solution was injected into the wider end of capillary with inlet inner diameter from 150, 185 or 218 μm. The calibration plots were linear (R(2) ∼ 0.9993) over a 0.060-1 μg/mL range for the proteins used, albumin and cytochrome c. The peak area RSDs from at least 20 independent measuremens were below 3.2%. This online pre-concentration technique produced a more than 196-fold increase in sensitivity, and it can be applied for detection of, e.g. the presence of albumin in urine (0.060 μg/mL).

  19. High Density Thermal Energy Storage with Supercritical Fluids

    Science.gov (United States)

    Ganapathi, Gani B.; Wirz, Richard

    2012-01-01

    A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

  20. iTOUGH2-EOS1SC. Multiphase Reservoir Simulator for Water under Sub- and Supercritical Conditions. User's Guide

    Energy Technology Data Exchange (ETDEWEB)

    Magnusdottir, Lilja [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Finsterle, Stefan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-03-01

    Supercritical fluids exist near magmatic heat sources in geothermal reservoirs, and the high enthalpy fluid is becoming more desirable for energy production with advancing technology. In geothermal modeling, the roots of the geothermal systems are normally avoided but in order to accurately predict the thermal behavior when wells are drilled close to magmatic intrusions, it is necessary to incorporate the heat sources into the modeling scheme. Modeling supercritical conditions poses a variety of challenges due to the large gradients in fluid properties near the critical zone. This work focused on using the iTOUGH2 simulator to model the extreme temperature and pressure conditions in magmatic geothermal systems.

  1. A study of radiation induced reactions in super critical water%超临界水的辐化反应研究

    Institute of Scientific and Technical Information of China (English)

    Y Katsumura

    2005-01-01

    It is known that water exists in supercritical state above 374C and 22.1MPa, where gas phase and liquid phase are merged into a single phase. In the supercritical state, the density is controllable by changing the pressure. The properties such as the ionic product, solubilities of salts, gas and organic compounds, and dielectric constant of supercritical water are very different from those of water at room temperature.Recently much attention has been paid to supercritical water because many possible applications such as synthesis of functional materials, waste oxidation, and biomass conversion have been proposed by using above peculiar properties of the supercritical water. Thus, much intensive work is in progress all over the world. In addition, a new concept of nuclear reactor using the supercritical water as a coolant has been proposed, which has been chosen by DOE, USA as one of the forth generation nuclear reactors.Therefore, radiation chemistry study of the supercritical water seems inevitably important, yet little work has been done so far. We started radiation chemistry study of supercritieal water by pulse radiolysis and γ radiolysis five years ago. We have observed hydrated electrons as a first target. We also measured inorganic radicals, metal ions, organic radicals in high temperature and supercritical water by a pulse radiolysis technique. It was found that absorption spectra of the transient species are dependent on temperature. Some transients show red-shift, and some bands are blue-shifted, with increasing temperatures. A G-value evaluation of water decomposition products was also done by using methyl viologen as a scavenger and it was revealed that the values are significantly dependent not only on temperature but also on density in supercritical water. An extended study on the behavior of solvated eleclions in different alcohols at high temperatures and super critical state is also in progress.

  2. Non-degradable triazine substrates of atrazine and cyanuric acid hydrothermally and in supercritical water under the UV-illuminated photocatalytic cooperation.

    Science.gov (United States)

    Horikoshi, Satoshi; Hidaka, Hisao

    2003-04-01

    Strong oxidation by titanium dioxide photocatalysis can occur by photodegradation of organic contaminants in air and water. Some endocrine disruptors such as 2,4-dichlorophenoxy acetic acid (;;; ), 2,4-dichlorophenol (;;; ), nonylphenol (; ), bisphenol A (), diethyl phthalate (; ), etc. which can be neither biodegraded by bacteria nor degraded thermally can be degraded by TiO(2) photocatalytic treatment. However, incomplete photomineralization partly occurred, when TiO(2) photocatalytic degradation is employed for the treatment of certain endocrine disruptors. For example, no atrazine pesticide having triazine skeleton can be completely mineralized even by a photocatalytic procedure; the photodegradation of atrazine ultimately stops at the intermediate step of cyanuric acid, which cannot be photodegraded even after long illumination times (). In this study, the decomposition of atrazine and cyanuric acid was carried out with a device combining photocatalytic degradation in supercritical water (scH(2)O) or hydrothermal water (hyH(2)O). Atrazine and cyanuric acid can be degraded by the cooperation of either scH(2)O or hyH(2)O and UV illuminated TiO(2)-photocatalytic dispersed system under the fixed pressure of 23 MPa at 623 K or 683 K in a 120-ml Hastelloy batch reactor. The photocatalytic degradation method under high temperature and pressure has found appropriate for the photocatalytic oxidation of acetic acid and 2-chlorobiphenyl under continuous flow conditions at 160 degrees C and 20 atm (). In addition, the wet peroxide oxidation of PCBs by high temperature and pressure has been reported (). The main aims of this research are following. (i): the degradation of atrazine and cyanuric acid within the scH(2)O or hyH(2)O, (ii) the decomposition of atrazine and cyanuric acid catalyzed by TiO(2) particles under scH(2)O or hyH(2)O, and the synergistic effect for several reactions with TiO(2) and scH(2)O or hyH(2)O, and (iii) the mineralization yield of nitrogen and

  3. Analysis of the temperature distribution of a water wall in the furnace of a supercritical steam power plant

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Norihide; Yagi, Nobuyoshi; Shibayama, Motoaki; Hayasaka, Hiroshi

    1988-07-25

    It is one of the important subjects for maintenance and management of modern boilers to establish the technology for estimating the residual life of a water wall tube composing a boiler furnace for a thermal power plant. Various studies on the residual life of material itself for a boiler water-wall tube have so far been in progress, but concerning a temperature of a water wall tube at a particular place inside a boiler furnace, the development of a practical method of analysis estimating the amount of the radiant heat transfer has not so far been progressed. Accordingly, in this report, a practical method for obtaining the temperature distribution of a water wall tube was examined and an idea that the radiant heat ray method was used for the analysis of radiant heat transfer and at the same time, the actual result of the operation was used for steam flow rate, etc. was elaborated and brought into operation. As a result, the following was revealed inter alia: (1) The heat flux became the maximum around the uppermost stages of the burners of the front and rear walls. (2) The temperature of a tube wall became the maximum around the uppermost stages of the burners in the center of the wall. (3) Deviation of the flow distribution affected the wall tube temperature considerably. The above is considered to suggest the adequacy of this analytical method. (12 figs, 9 refs)

  4. Electronic Tongue for Quantitation of Contaminants in Water

    Science.gov (United States)

    Buehler, Marlin; Kuhlman, Gregory

    2004-01-01

    An assembly of sensors, denoted an electronic tongue, is undergoing development as a prototype of compact devices for use in measuring concentrations of contaminants in water. Thus far, the electronic tongue has been tested on ions of Cu, Zn, Pb, and Fe and shown to respond to concentrations as low as about 10 parts per million. This electronic tongue is expected to be capable of measuring concentrations of other metal ions and organic compounds. Potential uses for electronic tongues include monitoring the chemical quality of water in a variety of natural, industrial, and laboratory settings; detecting micro-organisms indirectly by measuring microbially influenced corrosion; and characterizing compounds of interest to the pharmaceutical and food industries. This version of the electronic tongue includes a heater, a temperature sensor, an array of ion-specific electrodes, an oxidation/ reduction sensor pair, an electrical-conductivity sensor, and an array of galvanic cells, all on one compact ceramic substrate. Special-purpose electronic excitation and readout circuitry for the sensors has also been constructed. The main advantage of the electronic tongue, relative to electrodes of this type used traditionally to assess water quality, is extreme ruggedness. The types of measurements that can be performed by use of the sensors on the electronic tongue are quite varied. The best combination of types of measurements for a given application depends on the specific contaminants that one seeks to detect. Experimental studies to identify such combinations were in progress at the time of reporting the information for this article.

  5. Thermalisation and recombination of subexcitation electrons in solid water

    Energy Technology Data Exchange (ETDEWEB)

    Goulet, T.; Jay-Gerin, J.-P. (Sherbrooke Univ., PQ (Canada). Faculte de Medicine); Patau, J.-P. (Toulouse-3 Univ., 31 (France))

    1990-01-01

    The results of Monte Carlo simulations of the thermalisation of subexcitation electrons in solid water are reported. In the simulations, the possibility is taken into account that, prior to being thermalised, the electrons either recombine with their parent cation (H{sub 2}O{sup +}), or undergo a dissociative attachment to water molecules. A particular emphasis is placed on the description of the recombination process and on the influence of the parent cation on the electron's motion. The simulations are performed for different initial electron energies E{sub o} in the subexcitations energy range (i.e. E{sub o} < 7.4 eV). For each of these energies, the mean thermalisation distance {sub th} and time {sub th} are determined, as well as the proportions P{sub rec} and P{sub dis} of subexcitation electrons which, instead of thermalising, undergo recombination or dissociative attachment. (author).

  6. Development of computational methods for the safety assessment of gas-cooled high-temperature and supercritical light-water reactors. Final report; Rechenmethoden zur Bewertung der Sicherheit von gasgekuehlten Hochtemperaturreaktoren und superkritischen Leichtwasserreaktoren. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, S.; Cron, D. von der; Hristov, H.; Lerchl, G.; Papukchiev, A.; Seubert, A.; Sureda, A.; Weis, J.; Weyermann, F.

    2012-12-15

    This report documents developments and results in the frame of the project RS1191 ''Development of computational methods for the safety assessment of gas-cooled high temperature and supercritical light-water reactors''. The report is structured according to the five work packages: 1. Reactor physics modeling of gas-cooled high temperature reactors; 2. Coupling of reactor physics and 3-D thermal hydraulics for the core barrel; 3. Extension of ATHLET models for application to supercritical reactors (HPLWR); 4. Further development of ATHLET for application to HTR; 5. Further development and validation of ANSYS CFX for application to alternative reactor concepts. Chapter 4 describes the extensions made in TORT-TD related to the simulation of pebble-bed HTR, e.g. spectral zone buckling, Iodine-Xenon dynamics, nuclear decay heat calculation and extension of the cross section interpolation algorithms to higher dimensions. For fast running scoping calculations, a time-dependent 3-D diffusion solver has been implemented in TORT-TD. For the PBMR-268 and PBMR-400 as well as for the HTR-10 reactor, appropriate TORT-TD models have been developed. Few-group nuclear cross sections have been generated using the spectral codes MICROX- 2 and DRAGON4. For verification and validation of nuclear cross sections and deterministic reactor models, MCNP models of reactor core and control rod of the HTR-10 have been developed. Comparisons with experimental data have been performed for the HTR-10 first criticality and control rod worth. The development of the coupled 3-D neutron kinetics and thermal hydraulics code system TORT-TD/ATTICA3D is documented in chapter 5. Similar to the couplings with ATHLET and COBRA-TF, the ''internal'' coupling approach has been implemented. Regarding the review of experiments and benchmarks relevant to HTR for validation of the coupled code system, the PBMR-400 benchmarks and the HTR-10 test reactor have been selected

  7. Drug delivery goes supercritical

    Directory of Open Access Journals (Sweden)

    Patrick J. Ginty

    2005-08-01

    Full Text Available In the field of drug delivery, the ability to control the size, morphology, and release of drug particles is fundamental to good targeting, but is often hampered by harsh processing conditions or inadequate methods; likewise for the processing of polymeric controlled-release systems. However, the use of supercritical fluids such as supercritical CO2 (scCO2 has provided a ‘clean’ and effective alternative to traditional methods of drug and polymer processing. In particular, scCO2 has a number of unique properties that make it possible to process both bioactive molecules and amorphous polymers without using toxic organic solvents or elevated temperatures. Here, we review the positive impact that supercritical fluids have had on the micronization, encapsulation, and impregnation of molecules of interest to both the pharmaceutical and biotechnology industries.

  8. Independent Research and Design of 600-MW Supercritical CFB Boiler

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In order to further develop and improve the technologies for large-capacity supercritical CFB boiler, the key technologies for large CFB boiler were systematically studied, based on the development of first domestically-made 210-MW and 330-MW CFB boilers. The scheme of 600-MW supercritical CFB boiler was designed, including the furnace structure, key components, steam-water system and auxiliary systems, which laid a technical foundation for the engineering applications.

  9. Isolation of Organochlorine Pesticide from Ginseng with Supercritical CO2

    Institute of Scientific and Technical Information of China (English)

    李淑芬; 王幼君; 全灿; 田松江

    2005-01-01

    The feasibility of removal of the organochlorine pesticides residues of hexachlorocyclohexane(BHC) from radix ginseng with supercritical CO2 was explored. Some factors, such as extraction pressure, extraction temperature, and kinds of co-solvents were investigated. The experimental results indicate that it is possible to reduce BHC residues in radix ginseng to the level of 0.1 × 10-6 with supercritical CO2 in the presence of suitable amount of co-solvent, such as water.

  10. Inactivation of E. coli K12 in buffered peptone water and apple cider by pilot-plant scale supercritical carbon dioxide system

    Science.gov (United States)

    There is increasing interest in non-thermal processing to inactivate foodborne pathogens and background microflora in juice products. Non-thermal pasteurization ensures safety and may offer better quality products than thermal pasteurization. Of non-thermal technologies, use of supercritical carbon ...

  11. COMPARISONS OF SOXHLET EXTRACTION, PRESSURIZED LIQUID EXTRACTION, SUPERCRITICAL FLUID EXTRACTION, AND SUBCRITICAL WATER EXTRACTION FOR ENVIRONMENTAL SOLIDS: RECOVERY, SELECTIVITY, AND EFFECTS ON SAMPLE MATRIX. (R825394)

    Science.gov (United States)

    Extractions of a polycyclic aromatic hydrocarbon (PAH)-contaminated soil from a former manufactured gas plant site were performed with a Soxhlet apparatus (18 h), by pressurized liquid extraction (PLE) (50 min at 100°C), supercritical fluid extraction (SFE) (1 h at 150°...

  12. COMPARISONS OF SOXHLET EXTRACTION, PRESSURIZED LIQUID EXTRACTION, SUPERCRITICAL FLUID EXTRACTION, AND SUBCRITICAL WATER EXTRACTION FOR ENVIRONMENTAL SOLIDS: RECOVERY, SELECTIVITY, AND EFFECTS ON SAMPLE MATRIX. (R825394)

    Science.gov (United States)

    Extractions of a polycyclic aromatic hydrocarbon (PAH)-contaminated soil from a former manufactured gas plant site were performed with a Soxhlet apparatus (18 h), by pressurized liquid extraction (PLE) (50 min at 100°C), supercritical fluid extraction (SFE) (1 h at 150°...

  13. Pyrolysis of a high-ash peat in supercritical water%泥炭在超临界水中热解的研究

    Institute of Scientific and Technical Information of China (English)

    张荣; 任辉; 孙东凯; 毕继诚

    2008-01-01

    The effects of the addition of CaO, temperature and residence time on the conversion and product yields of a high-ash peat in supercritical water was investigated. The experiments were carried out in an autoclave in the temperature range of 623 K~773 K at pressure up to 30 MPa. At a Ca/C molar ratio of 0.46, almost no CO2 remained in gas phase. It was found that CaO facilitates the extraction of volatile matter from peat and the decomposition of volatile matter to small molecular compounds. Moreover, CaO catalyses the steam reforming reaction of hydrocarbons and the water-shift reaction. The addition of KOH might favor the reforming reaction of oil product to hydrogen and carbon dioxide. Furthermore, the yield of oil reaches a maximum at the temperature approximately 723K. A threefold increase in the yield of oil product was observed under 36.5 MPa compared with pyrolysis. However, the polar compounds decomposed with the prolongation of reaction time.%以氧化钙做为催化剂和CO2化学固定剂,详细考察了Ca/C摩尔比、反应温度﹑停留时间、压力等条件对泥炭在超临界水中转化的影响.在723 K,Ca/C摩尔比为0.46时,CO2被完全固定,在气相产物中只有氢气、甲烷和低碳烃,碳转化率由未添加CaO时的68.73%提高到85.36%.CaO能够促进泥炭的裂解,并对烃类的重整反应和水煤气变换反应起到催化作用.液相产物的收率在723 K达到极大值,在36.5 MPa,液相产物的收率是热解条件下的3倍,随着停留时间的延长,液相产物中的极性组分发生分解.

  14. Materials processing using supercritical fluids

    Directory of Open Access Journals (Sweden)

    Orlović Aleksandar M.

    2005-01-01

    Full Text Available One of the most interesting areas of supercritical fluids applications is the processing of novel materials. These new materials are designed to meet specific requirements and to make possible new applications in Pharmaceuticals design, heterogeneous catalysis, micro- and nano-particles with unique structures, special insulating materials, super capacitors and other special technical materials. Two distinct possibilities to apply supercritical fluids in processing of materials: synthesis of materials in supercritical fluid environment and/or further processing of already obtained materials with the help of supercritical fluids. By adjusting synthesis parameters the properties of supercritical fluids can be significantly altered which further results in the materials with different structures. Unique materials can be also obtained by conducting synthesis in quite specific environments like reversed micelles. This paper is mainly devoted to processing of previously synthesized materials which are further processed using supercritical fluids. Several new methods have been developed to produce micro- and nano-particles with the use of supercritical fluids. The following methods: rapid expansion of supercritical solutions (RESS supercritical anti-solvent (SAS, materials synthesis under supercritical conditions and encapsulation and coating using supercritical fluids were recently developed.

  15. Supercritical Synthesis of Biodiesel

    Directory of Open Access Journals (Sweden)

    Michel Vaultier

    2012-07-01

    Full Text Available The synthesis of biodiesel fuel from lipids (vegetable oils and animal fats has gained in importance as a possible source of renewable non-fossil energy in an attempt to reduce our dependence on petroleum-based fuels. The catalytic processes commonly used for the production of biodiesel fuel present a series of limitations and drawbacks, among them the high energy consumption required for complex purification operations and undesirable side reactions. Supercritical fluid (SCF technologies offer an interesting alternative to conventional processes for preparing biodiesel. This review highlights the advances, advantages, drawbacks and new tendencies involved in the use of supercritical fluids (SCFs for biodiesel synthesis.

  16. Comparison of the secondary electrons produced by proton and electron beams in water

    Energy Technology Data Exchange (ETDEWEB)

    Kia, Mohammad Reza, E-mail: m-r-kia@aut.ac.ir; Noshad, Houshyar [Department of Energy Engineering and Physics, Amirkabir University of Technology (Tehran Polytechnic), P.O. Box 15875-4413, Hafez Avenue, Tehran (Iran, Islamic Republic of)

    2016-05-15

    The secondary electrons produced in water by electron and proton beams are compared with each other. The total ionization cross section (TICS) for an electron impact in water is obtained by using the binary-encounter-Bethe model. Hence, an empirical equation based on two adjustable fitting parameters is presented to determine the TICS for proton impact in media. In order to calculate the projectile trajectory, a set of stochastic differential equations based on the inelastic collision, elastic scattering, and bremsstrahlung emission are used. In accordance with the projectile trajectory, the depth dose deposition, electron energy loss distribution in a certain depth, and secondary electrons produced in water are calculated. The obtained results for the depth dose deposition and energy loss distribution in certain depth for electron and proton beams with various incident energies in media are in excellent agreement with the reported experimental data. The difference between the profiles for the depth dose deposition and production of secondary electrons for a proton beam can be ignored approximately. But, these profiles for an electron beam are completely different due to the effect of elastic scattering on electron trajectory.

  17. Comparison of the secondary electrons produced by proton and electron beams in water

    Science.gov (United States)

    Kia, Mohammad Reza; Noshad, Houshyar

    2016-05-01

    The secondary electrons produced in water by electron and proton beams are compared with each other. The total ionization cross section (TICS) for an electron impact in water is obtained by using the binary-encounter-Bethe model. Hence, an empirical equation based on two adjustable fitting parameters is presented to determine the TICS for proton impact in media. In order to calculate the projectile trajectory, a set of stochastic differential equations based on the inelastic collision, elastic scattering, and bremsstrahlung emission are used. In accordance with the projectile trajectory, the depth dose deposition, electron energy loss distribution in a certain depth, and secondary electrons produced in water are calculated. The obtained results for the depth dose deposition and energy loss distribution in certain depth for electron and proton beams with various incident energies in media are in excellent agreement with the reported experimental data. The difference between the profiles for the depth dose deposition and production of secondary electrons for a proton beam can be ignored approximately. But, these profiles for an electron beam are completely different due to the effect of elastic scattering on electron trajectory.

  18. Electron Delocalization Determined Anomalous Stability in Small Water Rings

    CERN Document Server

    Wang, Bo; Dai, Xing; Song, Ruixia; Meng, Yan; Wang, Zhigang; Zhang, Ruiqin

    2013-01-01

    Water clusters are known to form through hydrogen bonding. However, this study shows that the formation of very small water clusters significantly deviates from this mechanism and instead involves both hydrogen bonding and electron delocalization. Our density functional theory calculations show that small water rings (H2O)n of n=3 or 4 show strong electron delocalization originating from both the hydrogen and oxygen atoms and extending to the ring center. This is very different from larger rings. Further energy decomposition of rings with n=3-6 demonstrates an upward trend in the polarization component but an decrease in the electrostatic and exchange repulsion components, presenting a minimum and accounting for 33% of interaction energy at n=3. This significantly promotes stability of the small water rings. Our findings provide a comprehensive analysis and improve our understanding of the stability characteristics of water clusters.

  19. High-Pressure Enzymatic Hydrolysis to Reveal Physicochemical and Thermal Properties of Bamboo Fiber Using a Supercritical Water Fermenter

    Directory of Open Access Journals (Sweden)

    H. P. S. Abdul Khalil

    2014-10-01

    Full Text Available Bamboo fiber was treated using a high-pressure enzyme hydrolysis process. The process performance was compared with the pulping and bleaching process for bamboo fiber. Several analytical methods, including field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry, and differential scanning calorimetry, were employed to determine the physicochemical and thermal properties of the treated cellulosic bamboo fiber. It was found that the pressurized enzyme hydrolysis treated bamboo fiber had the most uniform morphological structure, along with lowest crystallinity and highest thermal stability. Thus, utilizing high-pressure enzyme hydrolysis is the most effective process for treating fiber to remove non-cellulosic components from the raw material, including lignin, hemicelluloses, and waxy materials.

  20. Fixed Bed Adsorption of Drugs on Silica Aerogel from Supercritical Carbon Dioxide Solutions

    OpenAIRE

    Giuseppe Caputo

    2013-01-01

    Supercritical adsorption coupled with the high adsorption capacity of silica aerogel allows the preparation of a new kind of delivery systems of poor water soluble drugs. In order to overcome drawbacks of conventional techniques where the use of liquid solvents can cause the fracture of aerogel porous structure, in this work a new adsorption process of drugs from a supercritical mixture is proposed. Adsorption takes place from a fluid solution of the drug in supercritical CO2 and ethanol as c...

  1. Petrophysical core characterization at supercritical geothermal conditions

    Science.gov (United States)

    Kummerow, Juliane; Raab, Siegfried

    2015-04-01

    There is a growing scientific interest in the exploitation of supercritical geothermal reservoirs to increase the efficiency of geothermal power plants. The utilisation of geothermal energy requires in any case the detailed knowledge of the reservoir. In reservoir engineering, the characterisation of the geothermal system by electrical resistivity tomography (ERT) is a common geophysical exploration and monitoring strategy. For a realistic interpretation of the field measurements it is necessary to know both, the physical properties of the rock and those of the interacting fluid at defined temperature and pressure conditions. While there have been made great effort in determine the physical and chemical properties of water above its critical point (Tcritical = 374.21° C and pcritical = 221.2 bar), the influence of fluid-rock interactions on petrophysical properties in supercritical aqueous systems is nearly unknown. At supercritical conditions the viscosity of the fluid is low, which enhances the mass transfer and diffusion-controlled chemical reactions. This may have considerable effects on the porosity and hydraulic properties of a rock. To investigate high-enthalpy fluid-rock systems, in the framework of the EU-funded project IMAGE we have built a new percolation set-up, which allows for the measurement of electrical resistivity and permeability of rock samples at controlled supercritical conditions of aqueous fluids (pore pressure = 400 bar and a temperature = 400° C). First results will be presented.

  2. 分子动力学模拟超临界水微观结构及自扩散系数%Microstructure and self-diffusion coefficient of supercritical water by molecular dynamics simulation

    Institute of Scientific and Technical Information of China (English)

    张乃强; 徐鸿; 白杨

    2011-01-01

    By using molecular dynamics simulation with COMPASS force field, microstructure and self-diffusion coefficient of supercritical water were researched. The results show that the effect of the hydrogen bond on supercritical water is weakened obviously, and still exist. The bond length and the bond angle of the water molecular changed rapidly in the region of 648-748 K. The bond length and the bond angle of the water molecular changed slowly in 748-973 K. The characteristic peaks of radial distribution function increased with the increase of temperature in the region of 648-748 K, and decreased with the increase of temperature in the region of 748-973 K, which indicated that short range structure orderliness of water was changing with the increase of temperature. The self-diffusion coefficients of supercritical water were two orders of magnitude higher than ambient water, and increased with the increase of temperature, decreased with the increase of pressure.%采用分子动力学模拟方法,选用COMPASS力场,对超临界水的微观结构和扩散系数进行了研究.结果表明,在超临界区水分子的氢键作用明显减弱,但是仍有氢键存在.水分子的键长和键角在温度为648~748 K时变化迅速,在温度为748~973 K时变化很小.径向分布函数特征峰值在温度为648~748 K时随温度的升高而增大,在温度为748~973K时随温度升高而减小,表明水分子近程结构有序性随温度变化.超临界水自扩散系数是常温常压水的2个数量级,随温度升高而增大,随压力的升高而减小.

  3. Electron density and electron temperature measurements in nanosecond pulse discharges over liquid water surface

    Science.gov (United States)

    Simeni Simeni, M.; Roettgen, A.; Petrishchev, V.; Frederickson, K.; Adamovich, I. V.

    2016-12-01

    Time-resolved electron density, electron temperature, and gas temperature in nanosecond pulse discharges in helium and O2-He mixtures near liquid water surface are measured using Thomson/pure rotational Raman scattering, in two different geometries, (a) ‘diffuse filament’ discharge between a spherical high-voltage electrode and a grounded pin electrode placed in a reservoir filled with distilled water, with the tip exposed, and (b) dielectric barrier discharge between the high-voltage electrode and the liquid water surface. A diffuse plasma filament generated between the electrodes in helium during the primary discharge pulse exhibits noticeable constriction during the secondary discharge pulse several hundred ns later. Adding oxygen to the mixture reduces the plasma filament diameter and enhances constriction during the secondary pulse. In the dielectric barrier discharge, diffuse volumetric plasma occupies nearly the entire space between the high voltage electrode and the liquid surface, and extends radially along the surface. In the filament discharge in helium, adding water to the container results in considerable reduction of plasma lifetime compared to the discharge in dry helium, by about an order of magnitude, indicating rapid electron recombination with water cluster ions. Peak electron density during the pulse is also reduced, by about a factor of two, likely due to dissociative attachment to water vapor during the discharge pulse. These trends become more pronounced as oxygen is added to the mixture, which increases net rate of dissociative attachment. Gas temperature during the primary discharge pulse remains near room temperature, after which it increases up to T ~ 500 K over 5 µs and decays back to near room temperature before the next discharge pulse several tens of ms later. As expected, electron density and electron temperature in diffuse DBD plasmas are considerably lower compared to peak values in the filament discharge. Use of Thomson

  4. Optimization of Polycyclic Aromatic Hydrocarbon (PAH) Extraction Efficiency Parameters for Sub- and Supercritical Water Extraction (SCWE) Instrument

    Science.gov (United States)

    Okada, Asahi A.

    2005-01-01

    Polycyclic aromatic hydrocarbons are a class of molecules composed of multiple, bonded benzene rings. As PAHS are believed to be present on Mars, positive confirmation of their presence on Mars is highly desirable. To extract PAHS, which have low volatility, a fluid extraction method is ideal, and one that does not utilize organic solvents is especially ideal for in situ instrumental analysis. The use of water as a solvent, which at subcritical pressures and temperatures is relatively non-Polar, has significant potential. As SCWE instruments have not yet been commercialized, all instruments are individually-built research prototypes: thus, initial efforts were intended to determine if extraction efficiencies on the JPL-built laboratory-scale SCWE instrument are comparable to differing designs built elsewhere. Samples of soil with certified reference concentrations of PAHs were extracted using SCWE as well as conventional Soxhlet extraction. Continuation of the work would involve extractions on JPL'S newer, portable SCWE instrument prototype to determine its efficiency in extracting PAHs.

  5. Corrosion Behavior of Ferritic/Martensitic Steels CNS-I and Modified CNS-II in Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    YANG Ying; YAN Qing-zhi; YANG Ya-feng; ZHANG Le-fu; GE Chang-chun

    2012-01-01

    The corrosion behaviors of CNS-I and modified CNS-II were evaluated by exposing to superciritical water (SCW) at 550℃ and 25 MPa with a dissolved oxygen concentration of 200× 10 ^-9 for up to 1 000 h. Detailed corrosion results of these two alloys were provided, including the growth rate of the oxide scales, microstructure of the oxide scales, distribution of phases and alloying elements. The mass gains of CNS-I and modified CNS-II were 609.73 mg/dm2 and 459.42 mg/dm2 , respectively, after exposing to SCW for 1 000 h. A duplex oxide scale with an outer porous magnetite layer and an inner relatively dense magnetite/spinel-mixed layer was identified on CNS-I and modified CNS-II after the test. The oxide scales were rather porous at the beginning of the test but the porosity decreased with increase of the exposure duration. It was found that Fe was enriched in the outer oxide layer, Cr was enriched in the inner oxide layer and O existed at a very high concnetration in the whole oxide scale. Other alloying elements such as Mo, W, Mn were depleted from the outer oxide layer and showed slightly enrichment in the inner oxide layer. The distributution of Ni was different from other elements, it was enriched in the interface bewteen the base metal and the oxide scale and depleted in the outer and inner oxide layers.

  6. 水在超临界二氧化碳中的溶解度%Solubility of water in supercritical CO2

    Institute of Scientific and Technical Information of China (English)

    蒋春跃; 吴建峰; 孙志娟; 潘勤敏

    2014-01-01

    The high value utilization of oleic acid of inferior-quality product is one of the effective ways to reduce the cost of biodiesel,and in order to make full use of azelaic acid of inferior-quality product in biodiesel,solid state polycondensation (SSP)based on supercritical fluid technology can be used for the preparation of polymer materials with ultra-high relative molecular mass,such as nylon 69 .SCCO2 can not only enhance the SSP process as a medium,but also can effectively remove the polycondensate (such as water),and promote the reaction,so the determination of water solubility in SCCO2 for the research of enhanced SSP process by SCCO2 is of great significance.The solubility of water in SCCO2 was measured by the static method at 313.15,333.15,353.15 and 373.15 K and pressures 8.0-18.0 MPa,and the effect of temperature and pressure on the solubility was investigated.The experimental results show that the solubility data range from water mole fraction of 0.254%(313.15 K,8.0 MPa)to 1.414% (373.15 K,18.0 MPa),and the solubility increases with the increasing of temperature and pressure.Moreover,the solubility data were calculated by using Peng-Robinson equation of state as well as the Chrastil modified model.Both calculations demonstrate satisfactory results,with an average absolute relative deviation (AARD)4.63% and 5 .89%,respectively.%生物柴油副品油酸的高值化利用是降低生物柴油成本的有效途径之一,为了充分利用生物柴油副品油酸中的壬二酸,用基于超临界流体技术(SCCO2)的固相缩聚方法可制得超高相对分子质量的尼龙69等高分子材料。SCCO2不仅可以作为增强SSP过程的介质使用,还可以有效地将缩聚物(如水等小分子缩聚物)脱除,促进反应的进行,因此测定水在超临界二氧化碳中的溶解度对研究SCCO2增强的SSP过程具有重要意义。文中采用静态法测定了水在超临界二氧化碳中的溶解度,温度为313.15,333

  7. Transmission and Trapping of Cold Electrons in Water Ice

    DEFF Research Database (Denmark)

    Balog, Richard; Cicman, Peter; Field, David

    2011-01-01

    Experiments are reported that show currents of low energy (“cold”) electrons pass unattenuated through crystalline ice at 135 K for energies between zero and 650 meV, up to the maximum studied film thickness of 430 bilayers, showing negligible apparent trapping. By contrast, both porous amorphous...... ice and compact crystalline ice at 40 K show efficient electron trapping. Ice at intermediate temperatures reveals metastable trapping that decays within a few hundred seconds at 110 K. Our results are the first to demonstrate full transmission of cold electrons in high temperature water ice...

  8. [KEEPING THE ELECTRON-DONOR PROPERTIES OF DRINKING WATER].

    Science.gov (United States)

    Gibert, K K; Stekhin, A A; Iakovleva, G V; Sul'ina, Iu S

    2015-01-01

    In a study there was performed the experimental evaluation of long-term structural--physical changes of the phase of associated water in drinking water treated in hypomagnetic conditions according to the the technology providing the retention of of ortho/para isomers of water in the presence of a catalyst--triplet oxygen. According to the results of measurements ofparameters of nano-associates formed in the water there was found a series ofconsistencies, allowing to determine the mechanisms of the impact of hypomagnetic treatment on the catalytic properties ofwater and long-term stability of its activated state, that provides the long-term maintenance of high biological activity of drinking water. In particular, under hypomagnetic conditions of the treatment there is formed denser packing of amorphous ice--VI in the composition of associates peroxide, serving as a kind of "reservoir" of atmospheric gases. In such a "reservoir" there realized higher pressure, compared with normal geophysical conditions, that stimulates the gas-phase reactions with the formation of dimers and trimers of oxygen existing in the 2-electron--active configurations with binding energies of 0.3 eVand ~0.2 eV providing phase modulation, resulting in condensation of environment additional electrons on paramagnetic oxygen, which provides the long-term maintenance of the electron--donor ability of water and electrically non-equilibrium state.

  9. Dye solubility in supercritical carbon dioxide fluid

    Directory of Open Access Journals (Sweden)

    Yan Jun

    2015-01-01

    Full Text Available Supercritical carbon dioxide fluid is an alternative solvent for the water of the traditional dyeing. The solubility of dyestuff affects greatly the dyeing process. A theoretical model for predicting the dye solubility is proposed and verified experimentally. The paper concludes that the pressure has a greater impact on the dyestuff solubility than temperature, and an optimal dyeing condition is suggested for the highest distribution coefficient of dyestuff.

  10. Supercritical fluid extraction of mercury species.

    Science.gov (United States)

    Foy, G P; Pacey, G E

    2003-12-23

    Supercritical fluid extraction was used to recover organic and inorganic mercury species. Variations in pressure, water, methanol, and chelator create methods that allowed separation of inorganic from organic mercury species. When extracted using a compromised set of extraction conditions, the order of extraction was methyl, phenyl and inorganic mercury. For the individually optimized conditions, quantitative recoveries were observed. Level as low as 20 ppb were extracted and then determined using ICP.

  11. Wettability-Water/brine Film Thickness Relationship and the Effect of Supercritical CO2 Pre-contact for CO2/brine/mineral Systems under Geologic CO2 Sequestration Conditions: Insights from Molecular Dynamics Simulations

    Science.gov (United States)

    Chen, C.; Song, Y.; Li, W.

    2016-12-01

    Injection CO2 into deep saline aquifers is one of the main options for geologic carbon sequestration (GCS). A successful GCS in saline aquifers requires full knowledge about CO2/brine/mineral systems under sequestration conditions to reduce uncertainties during subsurface storage of CO2. Adsorbed water film thickness and wettability on mineral surfaces are two key characteristics for CO2/brine/mineral systems. Wettability and water/brine film thickness have been measured experimentally and predicted by molecular simulation (MD) studies. However, these studies only consider the films apart from contact angles. Investigations on wettability for CO2/brine/mineral systems only consider contact angles without measurements on film thickness. The relationship between film thicknesses with water contact angles is open to questions. In this paper, MD simulations have been performed to investigate the interrelationship between water film thicknesses and water contact angles. Three silica surfaces with different silanol group number densities (Q3, Q3-50%, Q3/Q4) were selected to represent silica surfaces with different wettabilities. We found that as water contact angle increases, the film thickness decreases. We also studied the effect of CO2-mineral pre-contact and found that: on Q3 surface, if a CO2 bubble was pre-contacted with the surface, it can remain on the surface without forming a water film; however, if a CO2 bubble was placed certain distances away from the surface, it formed a water film. Wettability analysis revealed that on the same surface, water contact angle was larger when there was no water film. These findings show that on some silica surfaces, water film may be destroyed by supercritical CO2 even the silica surfaces are hydrophilic. A water film rupture mechanism was propsed for CO2 adhesion on mineral surfaces [Wang (2013) Environ. Sci. Technol. 47, 11858; Zhang (2016) Environ. Sci. Technol. Lett. 10.1021/acs.estlett.5b00359]. The rupture of water film

  12. Electronically excited states of sodium-water clusters

    Science.gov (United States)

    Schulz, Claus Peter; Bobbert, Christiana; Shimosato, Taku; Daigoku, Kota; Miura, Nobuaki; Hashimoto, Kenro

    2003-12-01

    The lowest electronically excited state of small Na(H2O)n clusters has been investigated experimentally and theoretically. The excitation energy as determined by the depletion spectroscopy method drops from 16 950 cm-1 for the sodium atom down to 9670 cm-1 when only three water molecules are attached to the Na atom. For larger clusters the absorption band shifts back towards higher energies and reaches 10 880 cm-1 for n=12. The experimental data are compared to quantum-chemical calculations at the Møeller-