WorldWideScience

Sample records for graphite hydrogen gas

  1. Erosion of graphite surface exposed to hot supersonic hydrogen gas

    Science.gov (United States)

    Sharma, O. P.

    1972-01-01

    A theoretical model based on laminar boundary layer flow equations was developed to predict the erosion rate of a graphite (AGCarb-101) surface exposed to a hot supersonic stream of hydrogen gas. The supersonic flow in the nozzle outside the boundary layer formed over the surface of the specimen was determined by assuming one-dimensional isentropic conditions. An overall surface reaction rate expression based on experimental studies was used to describe the interaction of hydrogen with graphite. A satisfactory agreement was found between the results of the computation, and the available experimental data. Some shortcomings of the model and further possible improvements are discussed.

  2. Trapping and detrapping of hydrogen in graphite materials exposed to hydrogen gas

    International Nuclear Information System (INIS)

    Atsumi, Hisao; Iseki, Michio; Shikama, Tatsuo.

    1994-01-01

    Measurements of hydrogen solubility have been performed for several unirradiated and neutron-irradiated graphite (and CFC) samples at temperatures between 973 and 1323 K under a ∼10 kPa hydrogen atmosphere. The hydrogen dissolution process has been studied and it is discussed here. The values of hydrogen solubility vary substantially among the samples up to about a factor of 16. A strong correlation has been observed between the values of hydrogen solubility and the degrees of graphitization determined by X-ray diffraction technique. The relation can be extended even for the neutron irradiated samples. Hydrogen dissolution into graphite can be explained with the trapping of hydrogen at defect sites (e.g. dangling carbon bonds) considering an equilibrium reaction between hydrogen molecules and the trapping sites. The migration of hydrogen in graphite is speculated to result from a sequence of detrapping and retrapping events with high energy activation processes. (author)

  3. Hydrogen storage in graphite nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Park, C.; Tan, C.D.; Hidalgo, R.; Baker, R.T.K.; Rodriguez, N.M. [Northeastern Univ., Boston, MA (United States). Chemistry Dept.

    1998-08-01

    Graphite nanofibers (GNF) are a type of material that is produced by the decomposition of carbon containing gases over metal catalyst particles at temperatures around 600 C. These molecularly engineered structures consist of graphene sheets perfectly arranged in a parallel, perpendicular or at angle orientation with respect to the fiber axis. The most important feature of the material is that only edges are exposed. Such an arrangement imparts the material with unique properties for gas adsorption because the evenly separated layers constitute the most ordered set of nanopores that can accommodate an adsorbate in the most efficient manner. In addition, the non-rigid pore walls can also expand so as to accommodate hydrogen in a multilayer conformation. Of the many varieties of structures that can be produced the authors have discovered that when gram quantities of a selected number of GNF are exposed to hydrogen at pressures of {approximately} 2,000 psi, they are capable of adsorbing and storing up to 40 wt% of hydrogen. It is believed that a strong interaction is established between hydrogen and the delocalized p-electrons present in the graphite layers and therefore a new type of chemistry is occurring within these confined structures.

  4. Hydrogen adsorption on and solubility in graphites

    International Nuclear Information System (INIS)

    Kanashenko, S.L.; Wampler, W.R.

    1996-01-01

    The experimental data on adsorption and solubility of hydrogen isotopes in graphite over a wide range of temperatures and pressures are reviewed. Langmuir adsorption isotherms are proposed for the hydrogen-graphite interaction. The entropy and enthalpy of adsorption are estimated, allowing for effects of relaxation of dangling sp 2 bonds. Three kinds of traps are proposed: edge carbon atoms of interstitial loops with an adsorption enthalpy relative to H 2 gas of -4.4 eV/H 2 (unrelaxed, Trap 1), edge carbon atoms at grain surfaces with an adsorption enthalpy of -2.3 eV/H 2 (relaxed, Trap 2), and basal plane adsorption sites with an enthalpy of +2.43 eV/H 2 (Trap 3). The adsorption capacity of different types of graphite depends on the concentration of traps which depends on the crystalline microstructure of the material. The number of potential sites for the 'true solubility' (Trap 3) is assumed to be about one site per carbon atom in all types of graphite, but the endothermic character of this solubility leads to a negligible H inventory compared to the concentration of hydrogen in type 1 and type 2 traps for temperatures and gas pressures used in the experiments. Irradiation with neutrons or carbon atoms increases the concentration of type 1 and type 2 traps from about 20 and 200 appm respectively for unirradiated (POCO AXF-5Q) graphite to about 1500 and 5000 appm, respectively, at damage levels above 1 dpa. (orig.)

  5. Hydrogen storage in graphitic nanofibres

    OpenAIRE

    McCaldin, Simon Roger

    2007-01-01

    There is huge need to develop an alternative to hydrocarbons fuel, which does not produce CO2 or contribute to global warming - 'the hydrogen economy' is such an alternative, however the storage of hydrogen is the key technical barrier that must be overcome. The potential of graphitic nanofibres (GNFs) to be used as materials to allow the solid-state storage of hydrogen has thus been investigated. This has been conducted with a view to further developing the understanding of the mechanism(s) ...

  6. Gas transport in graphitic materials

    International Nuclear Information System (INIS)

    Hoinkis, E.

    1995-02-01

    The characterization of the gas transport properties of porous solids is of interest in several fields of science and technology. Many catalysts, adsorbents, soils, graphites and carbons are porous. The gas transport through most porous solids can be well described by the dusty gas model invented by Evans, Watson and Mason. This model includes all modes of gas tranport under steady-state conditions, which are Knudsen diffusion, combined Knudsen/continuum diffusion and continuum diffusion, both for gas pairs with equal and different molecular weights. In the absence of a pressure difference gas transport in a pore system can be described by the combined Knudsen/continuum diffusion coefficient D 1 for component 1 in the pores, the Knudsen diffusion coefficient D 1K in the pores, and the continuum diffusion coefficient D 12 for a binary mixture in the pores. The resistance to stationary continuum diffusion of the pores is characterized by a geometrical factor (ε/τ) 12 = (ε/τ)D 12 , were D 12 is the continuum diffusion coefficient for a binary mixture in free space. The Wicke-Kallenbach method was often used to measure D 1 as function of pressure. D 12 and D 1K can be derived from a plot 1/D 1 νs P, and ε/τcan be calculated since D 12 is known. D 1K and the volume of dead end pores can be derived from transient measurements of the diffusional flux at low pressures. From D 1K the expression (ε/τ c ) anti l por may be calculated, which characterizes the pore system for molecular diffusion, where collisions with the pore walls are predominant. (orig.)

  7. Interaction of the Helium, Hydrogen, Air, Argon, and Nitrogen Bubbles with Graphite Surface in Water.

    Science.gov (United States)

    Bartali, Ruben; Otyepka, Michal; Pykal, Martin; Lazar, Petr; Micheli, Victor; Gottardi, Gloria; Laidani, Nadhira

    2017-05-24

    The interaction of the confined gas with solid surface immersed in water is a common theme of many important fields such as self-cleaning surface, gas storage, and sensing. For that reason, we investigated the gas-graphite interaction in the water medium. The graphite surface was prepared by mechanical exfoliation of highly oriented pyrolytic graphite (HOPG). The surface chemistry and morphology were studied by X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy. The surface energy of HOPG was estimated by contact angle measurements using the Owens-Wendt method. The interaction of gases (Ar, He, H 2 , N 2 , and air) with graphite was studied by a captive bubble method, in which the gas bubble was in contact with the exfoliated graphite surface in water media. The experimental data were corroborated by molecular dynamics simulations and density functional theory calculations. The surface energy of HOPG equaled to 52.8 mJ/m 2 and more of 95% of the surface energy was attributed to dispersion interactions. The results on gas-surface interaction indicated that HOPG surface had gasphilic behavior for helium and hydrogen, while gasphobic behavior for argon and nitrogen. The results showed that the variation of the gas contact angle was related to the balance between the gas-surface and gas-gas interaction potentials. For helium and hydrogen the gas-surface interaction was particularly high compared to gas-gas interaction and this promoted the favorable interaction with graphite surface.

  8. Hydrogen pumping and release by graphite under high flux plasma bombardment

    International Nuclear Information System (INIS)

    Hirooka, Y.; Leung, W.K.; Conn, R.W.; Goebel, D.M.; LaBombard, B.; Nygren, R.; Wilson, K.L.

    1988-01-01

    Inert gas (helium or argon) plasma bombardment has been found to increase the surface gas adsorptivity of isotropic graphite (POCO-graphite), which can then getter residual gases in a high vacuum system. The inert gas plasma bombardment was carried out at a flux ≅ 1 x 10 18 ions s -1 cm -2 to a fluence of the order of 10 21 ions/cm 2 and at temperatures around 800 0 C. The gettering capability of graphite can be easily recovered by repeating inert gas plasma bombardment. The activated graphite surface exhibits a smooth, sponge-like morphology with significantly increased pore openings, which correlates with the observed increase in the surface gas adsorptivity. The activated graphite surface has been observed to pump hydrogen plasma particles as well. From calibrated H-alpha measurements, the dynamic hydrogen retention capacity is evaluated to be as large as 2 x 10 18 H/cm 2 at temperatures below 100 0 C and at a plasma bombarding energy of 300 eV. The graphite temperature was varied between 15 and 480 0 C. Due to the plasma particle pumping capability, hydrogen recycling from the activated graphite surface is significantly reduced, relative to that from a pre-saturated surface. A pre-saturated surface was also observed to reproducibly pump a hydrogen plasma to a concentration of 9.5 x 10 17 H/cm 2 . The hydrogen retention capacity of graphite is found to decrease with increasing temperature. A transient pumping mechanism associated with the sponge-like surface morphology is conjectured to explain the large hydrogen retention capacity. Hydrogen release behavior under helium and argon plasma bombardment was also investigated, and the result indicated the possibility of some in-pore retrapping effect. 43 refs., 11 figs

  9. Release enhancement of tritium from graphite by addition of hydrogen

    International Nuclear Information System (INIS)

    Saeki, Masakatsu; Masaki, N.M.

    1989-01-01

    The release behavior of tritium from graphite was studied in pure He and He + H 2 atmosphere. The release from powdered graphite was significantly enhanced in hydrogen environment. Apparent diffusion coefficients of tritium in graphite also became much higher in an atmosphere containing hydrogen than values obtained in pure helium atmosphere. A careful investigation of the release processes resulted in the conclusion that the most important process of tritium behaviour in graphite was diffusion, but the desorption process of tritium from the surface played a significant role. The enhancement of the desorption process was controlled by atomic hydrogen. (orig.)

  10. Hydrogen gas detector

    International Nuclear Information System (INIS)

    Bohl, T.L.

    1982-01-01

    A differential thermocouple hydrogen gas detector has one thermocouple junction coated with an activated palladium or palladium-silver alloy catalytic material to allow heated hydrogen gas to react with the catalyst and raise the temperature of that junction. The other juction is covered with inert glass or epoxy resin, and does not experience a rise in temperature in the presence of hydrogen gas. A coil heater may be mounted around the thermocouple junctions to heat the hydrogen, or the gas may be passed through a heated block prior to exposing it to the thermocouples

  11. Hydrogen pumping and release by graphite under high flux plasma bombardment

    International Nuclear Information System (INIS)

    Hirooka, Y.; Leung, W.K.; Conn, R.W.; Goebel, D.M.; Labombard, B.; Nygren, R.; Wilson, K.L.

    1988-01-01

    Inert gas (helium or argon) plasma bombardment has been found to increase the surface gas adsorptivity of isotropic graphite (POCO-graphite), which can then getter residual gases in a high vacuum system. The inert gas plasma bombardment was carried out at a flux ∼ 1 x 10 18 ions s -1 cm -2 to a fluence of the order of 10 21 ions/cm 2 and at temperatures around 800 degree C. The plasma bombarding energy was varied between 100 and 200 eV. The gettering speed of the activated graphite surface is estimated to be as large as 25 liters s -1 cm -2 at total pressures between 10 -6 and 10 -7 torr. The gettering capacity estimated is 0.025 torr-liter/cm 2 at room temperature. The gettering capability of graphite can be easily recovered by repeating inert gas plasma bombardment. The activated graphite surface exhibits a smooth, sponge-like morphology with significantly increased pore openings, which correlates with the observed increase in the surface gas adsorptivity. The activated graphite surface has been observed to pump hydrogen plasma particles as well. From calibrated H-alpha measurements, the dynamic hydrogen retention capacity is evaluated to be as large as 2 x 10 18 H/cm 2 at temperatures below 100 degree C and at a plasma bombarding energy of 300 eV

  12. Forming gas treatment of lithium ion battery anode graphite powders

    Science.gov (United States)

    Contescu, Cristian Ion; Gallego, Nidia C; Howe, Jane Y; Meyer, III, Harry M; Payzant, Edward Andrew; Wood, III, David L; Yoon, Sang Young

    2014-09-16

    The invention provides a method of making a battery anode in which a quantity of graphite powder is provided. The temperature of the graphite powder is raised from a starting temperature to a first temperature between 1000 and 2000.degree. C. during a first heating period. The graphite powder is then cooled to a final temperature during a cool down period. The graphite powder is contacted with a forming gas during at least one of the first heating period and the cool down period. The forming gas includes H.sub.2 and an inert gas.

  13. Hydrogen storage material and process using graphite additive with metal-doped complex hydrides

    Science.gov (United States)

    Zidan, Ragaiy [Aiken, SC; Ritter, James A [Lexington, SC; Ebner, Armin D [Lexington, SC; Wang, Jun [Columbia, SC; Holland, Charles E [Cayce, SC

    2008-06-10

    A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

  14. Management of graphite material: a key issue for High Temperature Gas Reactor system (HTGR)

    International Nuclear Information System (INIS)

    Bourdeloie, C.; Marimbeau, P.; Robin, J.C.; Cellier, F.

    2005-01-01

    Graphite material is used in nuclear High Temperature Gas-cooled Reactors (HTGR, Fig.1) as moderator, thermal absorber and also as structural components of the core (Fig.2). This type of reactor was selected by the Generation IV forum as a potential high temperature provider for supplying hydrogen production plants and is under development in France in the frame of the AREVA ANTARES program. In order to select graphite grades to be used in these future reactors, the requirements for mechanical, thermal, physical-chemical properties must match the internal environment of the nuclear core, especially with regard to irradiation effect. Another important aspect that must be addressed early in design is the waste issue. Indeed, it is necessary to reduce the amount of nuclear waste produced by operation of the reactor during its lifetime. Preliminary assessment of the nuclear waste output for an ANTARES type 280 MWe HTGR over 60 year-lifetime gives an estimated 6000 m 3 of activated graphite waste. Thus, reducing the graphite waste production is an important issue for any HTGR system. First, this paper presents a preliminary inventory of graphite waste fluxes coming from a HTGR, in mass and volume, with magnitudes of radiological activities based on activation calculations of graphite during its stay in the core of the reactor. Normalized data corresponding to an output of 1 GWe.year electricity allows comparison of the waste production with other nuclear reactor systems. Second, possible routes to manage irradiated graphite waste are addressed in both the context of French nuclear waste management rules and by comparison to other national regulations. Routes for graphite waste disposal studied in different countries (concerning existing irradiated graphite waste) will be discussed with regard to new issues of large graphite waste from HTGR. Alternative or complementary solutions aiming at lowering volume of graphite waste to be managed will be presented. For example

  15. Experiments to Measure Hydrogen Release from Graphite Walls During Disruptions in DIII-D

    International Nuclear Information System (INIS)

    Hollmann, E.M.; Pablant, N.A.; Rudakov, D.L.; Boedo, J.A.; Brooks, N.H.; Jernigan, Thomas C.; Pigarov, A.Y.

    2009-01-01

    Spectroscopy and wall the bake-out measurements are performed in the DIII-D tokamak to estimate the amount of hydrogen stored in and released from the walls during disruptions. Both naturally occurring disruptions and disruptions induced by massive gas injection (MGI) are investigated. The measurements indicate that both types of disruptions cause a net release of order 10(21) hydrogen (or deuterium) atoms from the graphite walls. This is comparable to the pre-disruptions plasma particle inventory, so the released hydrogen is important for accurate modeling of disruptions. However, the amount of hydrogen released is small compared to the total saturated wall inventory of order 10(22)-10(23), So it appears that many disruptions are necessary to provide full pump-out of the vessel walls. (C) 2009 Published by Elsevier B.V.

  16. Graphite development for gas-cooled reactors in the USA

    International Nuclear Information System (INIS)

    Burchell, T.D.

    1991-01-01

    This document discusses Modular High-Temperature Gas-Cooled Reactor (MHTGR) graphite activities in the USA which currently include the following research and development tasks: coke examination; effects of irradiation; variability of physical properties (mechanical, thermal-physical, and fracture); fatigue behavior, oxidation behavior; NDE techniques; structural design criteria; and carbon-carbon composite control rod clad materials. These tasks support nuclear grade graphite manufacturing technology including nondestructive examination of billets and components. Moreover, data shall be furnished to support design and licensing of graphite components for the MHTGR

  17. Graphite oxide and molybdenum disulfide composite for hydrogen evolution reaction

    Science.gov (United States)

    Niyitanga, Theophile; Jeong, Hae Kyung

    2017-10-01

    Graphite oxide and molybdenum disulfide (GO-MoS2) composite is prepared through a wet process by using hydrolysis of ammonium tetrathiomolybdate, and it exhibits excellent catalytic activity of the hydrogen evolution reaction (HER) with a low overpotential of -0.47 V, which is almost two and three times lower than those of precursor MoS2 and GO. The high performance of HER of the composite attributes to the reduced GO supporting MoS2, providing a conducting network for fast electron transport from MoS2 to electrodes. The composite also shows high stability after 500 cycles, demonstrating a synergistic effect of MoS2 and GO for efficient HER.

  18. Gas Phase Hydrogenation of Levulinic Acid to gamma-Valerolactone

    NARCIS (Netherlands)

    Bonrath, Werner; Castelijns, Anna Maria Cornelia Francisca; de Vries, Johannes Gerardus; Guit, Rudolf Philippus Maria; Schuetz, Jan; Sereinig, Natascha; Vaessen, Henricus Wilhelmus Leonardus Marie

    The gas phase hydrogenation of levulinic acid to gamma-valerolactone over copper and ruthenium based catalysts in a continuous fixed-bed reactor system was investigated. Among the catalysts a copper oxide based one [50-75 % CuO, 20-25 % SiO2, 1-5 % graphite, 0.1-1 % CuCO3/Cu(OH)(2)] gave

  19. Molecular dynamics simulation of chemical sputtering of hydrogen atom on layer structured graphite

    International Nuclear Information System (INIS)

    Ito, A.; Wang, Y.; Irle, S.; Morokuma, K.; Nakamura, H.

    2008-10-01

    Chemical sputtering of hydrogen atom on graphite was simulated using molecular dynamics. Especially, the layer structure of the graphite was maintained by interlayer intermolecular interaction. Three kinds of graphite surfaces, flat (0 0 0 1) surface, armchair (1 1 2-bar 0) surface and zigzag (1 0 1-bar 0) surface, are dealt with as targets of hydrogen atom bombardment. In the case of the flat surface, graphene layers were peeled off one by one and yielded molecules had chain structures. On the other hand, C 2 H 2 and H 2 are dominant yielded molecules on the armchair and zigzag surfaces, respectively. In addition, the interaction of a single hydrogen isotope on a single graphene is investigated. Adsorption, reflection and penetration rates are obtained as functions of incident energy and explain hydrogen retention on layered graphite. (author)

  20. Graphite-MicroMégas, a tool for DNA modeling

    OpenAIRE

    Hornus , Samuel; Larivière , Damien

    2011-01-01

    National audience; MicroMégas is the current state of an ongoing effort to develop tools for modeling biological assembly of molecules. We here present its DNA modeling part. MicroMégas is implemented as a plug-in to Graphite, which is a research plat- form for computer graphics, 3D modeling and numerical geometry that is developed by members of the ALICE team of INRIA.; Nous décrivons l'outils MicroMégas et les techniques qu'il met en jeu pour la modélisation d'assemblage de molécule, en par...

  1. The effect of radiolytically induced gas pressure on the CO2/CO/graphite system

    International Nuclear Information System (INIS)

    Curtis, A.R.; Faircloth, R.L.; Norwood, K.S.

    1980-03-01

    When radiolysed, carbon dioxide corrodes graphite to produce carbon monoxide, which can blow gas out of the graphite pores. This memorandum demonstrates how to calculate this effect, both analytically and numerically with FACSIMILE, and shows how it depends on dose rate, gas composition, specimen size and graphite diffusivity, for cylindrical geometry. The effect is very small for all cases of interest. (author)

  2. Analysis of Off Gas From Disintegration Process of Graphite Matrix by Electrochemical Method

    International Nuclear Information System (INIS)

    Tian Lifang; Wen Mingfen; Chen Jing

    2010-01-01

    Using electrochemical method with salt solutions as electrolyte, some gaseous substances (off gas) would be generated during the disintegration of graphite from high-temperature gas-cooled reactor fuel elements. The off gas is determined to be composed of H 2 , O 2 , N 2 , CO 2 and NO x by gas chromatography. Only about 1.5% graphite matrix is oxidized to CO 2 . Compared to the direct burning-graphite method, less off gas,especially CO 2 , is generated in the disintegration process of graphite by electrochemical method and the treatment of off gas becomes much easier. (authors)

  3. Graphite

    Science.gov (United States)

    Robinson, Gilpin R.; Hammarstrom, Jane M.; Olson, Donald W.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Graphite is a form of pure carbon that normally occurs as black crystal flakes and masses. It has important properties, such as chemical inertness, thermal stability, high electrical conductivity, and lubricity (slipperiness) that make it suitable for many industrial applications, including electronics, lubricants, metallurgy, and steelmaking. For some of these uses, no suitable substitutes are available. Steelmaking and refractory applications in metallurgy use the largest amount of produced graphite; however, emerging technology uses in large-scale fuel cell, battery, and lightweight high-strength composite applications could substantially increase world demand for graphite.Graphite ores are classified as “amorphous” (microcrystalline), and “crystalline” (“flake” or “lump or chip”) based on the ore’s crystallinity, grain-size, and morphology. All graphite deposits mined today formed from metamorphism of carbonaceous sedimentary rocks, and the ore type is determined by the geologic setting. Thermally metamorphosed coal is the usual source of amorphous graphite. Disseminated crystalline flake graphite is mined from carbonaceous metamorphic rocks, and lump or chip graphite is mined from veins in high-grade metamorphic regions. Because graphite is chemically inert and nontoxic, the main environmental concerns associated with graphite mining are inhalation of fine-grained dusts, including silicate and sulfide mineral particles, and hydrocarbon vapors produced during the mining and processing of ore. Synthetic graphite is manufactured from hydrocarbon sources using high-temperature heat treatment, and it is more expensive to produce than natural graphite.Production of natural graphite is dominated by China, India, and Brazil, which export graphite worldwide. China provides approximately 67 percent of worldwide output of natural graphite, and, as the dominant exporter, has the ability to set world prices. China has significant graphite reserves, and

  4. Hydrogen gas sample environment for TOSCA

    International Nuclear Information System (INIS)

    Kibble, Mark G; Ramirez-Cuesta, Anibal J; Goodway, Chris M; Evans, Beth E; Kirichek, Oleg

    2014-01-01

    The idea of using hydrogen as a fuel has gained immense popularity over many years. Hydrogen is abundant, can be produced from renewable resources and is not a greenhouse gas. However development of hydrogen based technology is impossible without understanding of physical and chemical processes that involve hydrogen sometime in extreme conditions such as high pressure or low and high temperatures. Neutron spectroscopy allows measurement of a hydrogen atom motion in variety of samples. Here we describe and discuss a sample environment kit developed for hydrogen gas experiment in a broad range of pressure up to 7 kbar and temperatures from 4 K to 473 K. We also describe para-hydrogen rig which produces para-hydrogen gas required for studying the rotational line of molecular hydrogen

  5. An enhanced hydrogen adsorption enthalpy for fluoride intercalated graphite compounds.

    Science.gov (United States)

    Cheng, Hansong; Sha, Xianwei; Chen, Liang; Cooper, Alan C; Foo, Maw-Lin; Lau, Garret C; Bailey, Wade H; Pez, Guido P

    2009-12-16

    We present a combined theoretical and experimental study on H(2) physisorption in partially fluorinated graphite. This material, first predicted computationally using ab initio molecular dynamics simulation and subsequently synthesized and characterized experimentally, represents a novel class of "acceptor type" graphite intercalated compounds that exhibit significantly higher isosteric heat of adsorption for H(2) at near ambient temperatures than previously demonstrated for commonly available porous carbon-based materials. The unusually strong interaction arises from the semi-ionic nature of the C-F bonds. Although a high H(2) storage capacity (>4 wt %) at room temperature is predicted not to be feasible due to the low heat of adsorption, enhanced storage properties can be envisaged by doping the graphitic host with appropriate species to promote higher levels of charge transfer from graphene to F(-) anions.

  6. Radiolytic and thermolytic bubble gas hydrogen composition

    Energy Technology Data Exchange (ETDEWEB)

    Woodham, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-12-11

    This report describes the development of a mathematical model for the estimation of the hydrogen composition of gas bubbles trapped in radioactive waste. The model described herein uses a material balance approach to accurately incorporate the rates of hydrogen generation by a number of physical phenomena and scale the aforementioned rates in a manner that allows calculation of the final hydrogen composition.

  7. A new technique for pumping hydrogen gas

    Science.gov (United States)

    Friedman, I.; Hardcastle, K.

    1970-01-01

    A system for pumping hydrogen gas without isotopic fractionation has been developed. The pump contains uranium metal, which when heated to about 80??C reacts with hydrogen to form UH3. The UH3 is heated to above 500??C to decompose the hydride and regenerate the hydrogen. ?? 1970.

  8. Internal dosimetry of tritiated hydrogen gas

    International Nuclear Information System (INIS)

    Peterman, B.F.; Johnson, J.R.; Dunford, D.W.; McElroy, R.G.C.

    1985-02-01

    This document is a report on experiments to quantify the doses that may occur from the tritium gas that is converted 'in vivo' to tritiated water following the exposure to tritiated hydrogen gas contaminated air. This report also includes theoretical evaluation of the radiological hazards from the uptake through skin of tritium from tritiated hydrogen adsorbed on surfaces

  9. Graphite-supported platinum catalysts: Effects of gas and aqueous phase treatments

    Energy Technology Data Exchange (ETDEWEB)

    Vleeming, J.H.; Kuster, B.F.M.; Marin, G.B. [Eindhoven Univ. of Technology (Netherlands)] [and others

    1997-03-01

    The effects on the platinum particle diameter and the available platinum surface area of a graphite-supported platinum catalyst resulting from pretreatments and from performing a selective oxidation reaction are investigated. In the gas phase considerable catalyst sintering occurs only in the presence of oxygen at 773 K due to extensive carbon burn-off, whereas in an aqueous phase platinum particle growth is limited upon oxidative treatment. A hydrogen treatment in aqueous phase at 363 K causes platinum particle growth, aggregate formation, and covering of metal sites. These phenomena become more important with increasing pH. Platinum particle growth and aggregate formation are attributed to platinum particle rather than platinum adatom mobility and is caused by the destruction of the oxygen-containing surface groups on the graphite support, which serve as anchorage sites for the platinum particles. Site covering is caused by products originating from the graphite support, which are formed as a result of the reductive treatments. When performing the aqueous phase oxidation of methyl {alpha}-D-glucopyranoside at 323 K and a pH of 9, catalyst modifications are small under oxidative conditions. Exposure of the catalyst for several hours to methyl {alpha}-D-glucopyranoside under the same conditions but in the absence of oxygen causes site covering. 50 refs., 9 figs., 1 tab.

  10. Searching for magnetism in hydrogenated graphene: Using highly hydrogenated graphene prepared via birch reduction of graphite oxides

    Czech Academy of Sciences Publication Activity Database

    Eng, A.Y.S.; Poh, H. L.; Šaněk, F.; Maryško, Miroslav; Matějková, Stanislava; Šofer, Z.; Pumera, M.

    2013-01-01

    Roč. 7, č. 7 (2013), s. 5930-5939 ISSN 1936-0851 R&D Projects: GA ČR GA13-20507S Institutional support: RVO:68378271 ; RVO:61388963 Keywords : hydrogenated graphene * graphane * graphite oxide * ferromagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism; CF - Physical ; Theoretical Chemistry (UOCHB-X) Impact factor: 12.033, year: 2013

  11. Sulfur-doped graphene via thermal exfoliation of graphite oxide in H2S, SO2, or CS2 gas.

    Science.gov (United States)

    Poh, Hwee Ling; Šimek, Petr; Sofer, Zdeněk; Pumera, Martin

    2013-06-25

    Doping of graphene with heteroatoms is an effective way to tailor its properties. Here we describe a simple and scalable method of doping graphene lattice with sulfur atoms during the thermal exfoliation process of graphite oxides. The graphite oxides were first prepared by Staudenmaier, Hofmann, and Hummers methods followed by treatments in hydrogen sulfide, sulfur dioxide, or carbon disulfide. The doped materials were characterized by scanning electron microscopy, high-resolution X-ray photoelectron spectroscopy, combustible elemental analysis, and Raman spectroscopy. The ζ-potential and conductivity of sulfur-doped graphenes were also investigated in this paper. It was found that the level of doping is more dramatically influenced by the type of graphite oxide used rather than the type of sulfur-containing gas used during exfoliation. Resulting sulfur-doped graphenes act as metal-free electrocatalysts for an oxygen reduction reaction.

  12. BIG hydrogen: hydrogen technology in the oil and gas sector

    International Nuclear Information System (INIS)

    2006-01-01

    The BIG Hydrogen workshop was held in Calgary, Alberta, Canada on February 13, 2006. About 60 representatives of industry, academia and government attended this one-day technical meeting on hydrogen production for the oil and gas industry. The following themes were identified from the presentations and discussion: the need to find a BIG hydrogen replacement for Steam Methane Reformer (SMR) because of uncertainty regarding cost and availability of natural gas, although given the maturity of SMR process (reliability, known capital cost) how high will H2 prices have to rise?; need for a national strategy to link the near-term and the longer-term hydrogen production requirements, which can take hydrogen from chemical feedstock to energy carrier; and in the near-term Canada should get involved in demonstrations and build expertise in large hydrogen systems including production and carbon capture and sequestration

  13. Graphites and composites irradiations for gas cooled reactor core structures

    International Nuclear Information System (INIS)

    Van der Laan, J.G.; Vreeling, J.A.; Buckthorpe, D.E.; Reed, J.

    2008-01-01

    Full text of publication follows. Material investigations are undertaken as part of the European Commission 6. Framework Programme for helium-cooled fission reactors under development like HTR, VHTR, GCFR. The work comprises a range of activities, from (pre-)qualification to screening of newly designed materials. The High Flux Reactor at Petten is the main test bed for the irradiation test programmes of the HTRM/M1, RAPHAEL and ExtreMat Integrated Projects. These projects are supported by the European Commission 5. and 6. Framework Programmes. To a large extent they form the European contribution to the Generation-IV International Forum. NRG is also performing a Materials Test Reactor project to support British Energy in preparing extended operation of their Advanced Gas-cooled Reactors (AGR). Irradiations of commercial and developmental graphite grades for HTR core structures are undertaken in the range of 650 to 950 deg C, with a view to get data on physical and mechanical properties that enable engineering design. Various C- and SiC-based composite materials are considered for support structures or specific components like control rods. Irradiation test matrices are chosen to cover commercial materials, and to provide insight on the behaviour of various fibre and matrix types, and the effects of architecture and manufacturing process. The programme is connected with modelling activities to support data trending, and improve understanding of the material behaviour and micro-structural evolution. The irradiation programme involves products from a large variety of industrial and research partners, and there is strong interaction with other high technology areas with extreme environments like space, electronics and fusion. The project on AGR core structures graphite focuses on the effects of high dose neutron irradiation and simultaneous radiolytic oxidation in a range of 350 to 450 deg C. It is aimed to provide data on graphite properties into the parameter space

  14. Gas storage cylinder formed from a composition containing thermally exfoliated graphite

    Science.gov (United States)

    Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor)

    2012-01-01

    A gas storage cylinder or gas storage cylinder liner, formed from a polymer composite, containing at least one polymer and a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m(exp 2)/g to 2600 m(exp 2)2/g.

  15. Investigation of Hydrogen and Nitrogen Content in Compacted Graphite Iron Production

    OpenAIRE

    Siafakas, Dimitrios

    2013-01-01

    The aim of this research, part of a wider program called SPOFIC, is to investigate how the casting procedure affects the concentration of hydrogen and nitrogen gases in Compacted Graphite Iron used for the production of truck cylinder blocks. Hydris equipment was used for the Hydrogen measurements and the Optical Emission Spectroscopy and combustion analysis methods were used for the nitrogen measurements. The experiment was performed in one of the cooperating foundries. It was found that Hyd...

  16. Room temperature hydrogen sensing with the graphite/ZnO nanorod junctions decorated with Pt nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Yatskiv, Roman; Grym, Jan; Gladkov, Petar; Černohorský, Ondřej; Vaniš, Jan; Maixner, J.; Dickerson, J.H.

    2016-01-01

    Roč. 116, February (2016), s. 124-129 ISSN 0038-1101 R&D Projects: GA MŠk(CZ) LD14111; GA ČR(CZ) GA15-17044S Institutional support: RVO:67985882 Keywords : Graphite based junction * Hydrogen sensor * Electrophoretic deposition Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.580, year: 2016

  17. Electron Charged Graphite-based Hydrogen Storage Material

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Chinbay Q. Fan; D Manager

    2012-03-14

    The electron-charge effects have been demonstrated to enhance hydrogen storage capacity using materials which have inherent hydrogen storage capacities. A charge control agent (CCA) or a charge transfer agent (CTA) was applied to the hydrogen storage material to reduce internal discharge between particles in a Sievert volumetric test device. GTI has tested the device under (1) electrostatic charge mode; (2) ultra-capacitor mode; and (3) metal-hydride mode. GTI has also analyzed the charge distribution on storage materials. The charge control agent and charge transfer agent are needed to prevent internal charge leaks so that the hydrogen atoms can stay on the storage material. GTI has analyzed the hydrogen fueling tank structure, which contains an air or liquid heat exchange framework. The cooling structure is needed for hydrogen fueling/releasing. We found that the cooling structure could be used as electron-charged electrodes, which will exhibit a very uniform charge distribution (because the cooling system needs to remove heat uniformly). Therefore, the electron-charge concept does not have any burden of cost and weight for the hydrogen storage tank system. The energy consumption for the electron-charge enhancement method is quite low or omitted for electrostatic mode and ultra-capacitor mode in comparison of other hydrogen storage methods; however, it could be high for the battery mode.

  18. Highly sensitive hydrogen sensor based on graphite-InP or graphite-GaN Schottky barrier with electrophoretically deposited Pd nanoparticles

    Directory of Open Access Journals (Sweden)

    Zdansky Karel

    2011-01-01

    Full Text Available Abstract Depositions on surfaces of semiconductor wafers of InP and GaN were performed from isooctane colloid solutions of palladium (Pd nanoparticles (NPs in AOT reverse micelles. Pd NPs in evaporated colloid and in layers deposited electrophoretically were monitored by SEM. Diodes were prepared by making Schottky contacts with colloidal graphite on semiconductor surfaces previously deposited with Pd NPs and ohmic contacts on blank surfaces. Forward and reverse current-voltage characteristics of the diodes showed high rectification ratio and high Schottky barrier heights, giving evidence of very small Fermi level pinning. A large increase of current was observed after exposing diodes to flow of gas blend hydrogen in nitrogen. Current change ratio about 700,000 with 0.1% hydrogen blend was achieved, which is more than two orders-of-magnitude improvement over the best result reported previously. Hydrogen detection limit of the diodes was estimated at 1 ppm H2/N2. The diodes, besides this extremely high sensitivity, have been temporally stable and of inexpensive production. Relatively more expensive GaN diodes have potential for functionality at high temperatures.

  19. Hydrogen storage in graphite nanofibers: effect of synthesis catalyst and pretreatment conditions.

    Science.gov (United States)

    Lueking, Angela D; Yang, Ralph T; Rodriguez, Nelly M; Baker, R Terry K

    2004-02-03

    A series of graphite nanofibers (GNFs) that were subjected to various pretreatments were used to determine how modifications in the carbon structure formed during either synthesis or pretreatment steps results in active or inactive materials for hydrogen storage. The nanofibers possessing a herringbone structure and a high degree of defects were found to exhibit the best performance for hydrogen storage. These materials were exposed to several pretreatment procedures, including oxidative, reductive, and inert environments. Significant hydrogen storage levels were found for several in situ pretreatments. Examination of the nanofibers by high-resolution transmission electron microscopy (TEM) after pretreatment and subsequent hydrogen storage revealed the existence of edge attack and an enhancement in the generation of structural defects. These findings suggest that pretreatment in certain environments results in the creation of catalytic sites that are favorable toward hydrogen storage. The best pretreatment resulted in a 3.8% hydrogen release after exposure at 69 bar and room temperature.

  20. Field effect-gas sensor for hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Plihal, M [Siemens A.G., Muenchen (Germany, F.R.). Forschungslaboratorium

    1977-01-01

    MIS diodes with palladium gate can be used to detect and to measure quantitatively the hydrogen concentration in gas mixtures. The dependence of the differential capacitance of these diodes on the partial pressure of hydrogen in nitrogen, oxygen and air is investigated. A theoretical model is developed which gives satisfactory agreement with most of the experimental results.

  1. Characteristics of hydrogen evolution and oxidation catalyzed by Desulfovibrio caledoniensis biofilm on pyrolytic graphite electrode

    International Nuclear Information System (INIS)

    Yu Lin; Duan Jizhou; Zhao Wei; Huang Yanliang; Hou Baorong

    2011-01-01

    Highlights: → The sulphate-reducing bacteria (SRB) have the ability to catalyze the hydrogen evolution and oxidation on pyrolytic graphite electrode. → The SRB biofilm decreases the overpotential and electron transfer resistance by the CV and EIS detection. → The SRB biofilm can transfer electrons to the 0.24 V polarized pyrolytic graphite electrode and the maximum current is 0.035 mA, which is attributed to SRB catalyzed hydrogen oxidation. → The SRB biofilm also can obtain electron from the -0.61 V polarized PGE to catalyze the hydrogen evolution. - Abstract: Hydrogenase, an important electroactive enzyme of sulphate-reducing bacteria (SRB), has been discovered having the capacity to connect its activity to solid electrodes by catalyzing hydrogen evolution and oxidation. However, little attention has been paid to similar electroactive characteristics of SRB. In this study, the electroactivities of pyrolytic graphite electrode (PGE) coated with SRB biofilm were investigated. Two corresponding redox peaks were observed by cyclic voltammetry detection, which were related to the hydrogen evolution and oxidation. Moreover, the overpotential for the reactions decreased by about 0.2 V in the presence of the SRB biofilm. When the PGE coated with the SRB biofilm was polarized at 0.24 V (vs. SHE), an oxidation current related to the hydrogen oxidation was found. The SRB biofilm was able to obtain electrons from the -0.61 V (vs. SHE) polarized PGE to form hydrogen, and the electron transfer resistance also decreased with the formation of SRB biofilm, as measured by the non-destructive electrochemical impendence spectroscopy detection. It was concluded that the hydrogen evolution and oxidation was an important way for the electron transfer between SRB biofilm and solid electrode in anaerobic environment.

  2. Charge Modulation in Graphitic Carbon Nitride as a Switchable Approach to High-Capacity Hydrogen Storage.

    Science.gov (United States)

    Tan, Xin; Kou, Liangzhi; Tahini, Hassan A; Smith, Sean C

    2015-11-01

    Electrical charging of graphitic carbon nitride nanosheets (g-C4 N3 and g-C3 N4 ) is proposed as a strategy for high-capacity and electrocatalytically switchable hydrogen storage. Using first-principle calculations, we found that the adsorption energy of H2 molecules on graphitic carbon nitride nanosheets is dramatically enhanced by injecting extra electrons into the adsorbent. At full hydrogen coverage, the negatively charged graphitic carbon nitride achieves storage capacities up to 6-7 wt %. In contrast to other hydrogen storage approaches, the storage/release occurs spontaneously once extra electrons are introduced or removed, and these processes can be simply controlled by switching on/off the charging voltage. Therefore, this approach promises both facile reversibility and tunable kinetics without the need of specific catalysts. Importantly, g-C4 N3 has good electrical conductivity and high electron mobility, which can be a very good candidate for electron injection/release. These predictions may prove to be instrumental in searching for a new class of high-capacity hydrogen storage materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Preparation of platinum-decorated porous graphite nanofibers, and their hydrogen storage behaviors.

    Science.gov (United States)

    Kim, Byung-Joo; Lee, Young-Seak; Park, Soo-Jin

    2008-02-15

    In this work, the hydrogen storage behaviors of porous graphite nanofibers (GNFs) decorated by Pt nanoparticles were investigated. The Pt nanoparticles were introduced onto the GNF surfaces using a well-known chemical reduction method. We investigated the hydrogen storage capacity of the Pt-doped GNFs for the platinum content range of 1.3-7.5 mass%. The microstructure of the Pt/porous GNFs was characterized by X-ray diffraction and transmission electron microscopy. The hydrogen storage behaviors of the Pt/GNFs were studied using a PCT apparatus at 298 K and 10 MPa. It was found that amount of hydrogen stored increased with increasing Pt content to 3.4 mass%, and then decreased. This result indicates that the hydrogen storage capacity of porous carbons is based on both their metal content and dispersion rate.

  4. The hydrogen economy - an opportunity for gas

    International Nuclear Information System (INIS)

    Soederbaum, J.; Martin, G.; O'Neill, C.

    2003-01-01

    Natural gas could play a pivotal role in any transition to a hydrogen economy-that is one of the findings of the recently-released National Hydrogen Study, commissioned by the Commonwealth Department of Industry, Tourism and Resources, and undertaken by the consulting firms ACIL Tasman and Parsons Brinckerhoff. The key benefits of hydrogen include zero emissions at the point of combustion (water is the main by-product) and its abundance Hydrogen can be produced from a range of primary energy sources including gas and coal, or through the electrolysis of water. Depending on the process used to manufacture hydrogen (especially the extent to which any associated carbon can be captured and sequestered), life-cycle emissions associated with its production and use can be reduced or entirely eliminated

  5. 3D microscopy of hydrogen and magnetic force on proton implanted microstructures in graphite

    International Nuclear Information System (INIS)

    Reichart, P.; Cluitmans, J.F.J.; Pakes, C.; Orbons, S.; Jamieson, D.N.

    2005-01-01

    We investigated the depth dependence of magnetic signals in proton irradiated graphite using a tilted microspot implantation followed by combined AFM/MFM analysis. This study is motivated by the not yet independently reproduced discovery of ferromagnetism in carbon materials created by proton irradiation. We present results of 3D hydrogen analysis of pristine and irradiated highly oriented pyrolytic graphite (HOPG). These results, previously presented in collaboration with universities in Leipzig and Munich, are summarized here and reveal a hydrogen level in pristine HOPG less than 0.3 at-ppm and that 2.25 MeV implanted hydrogen is located within a peak confined to the end of range with no evidence of diffusion broadening. For implanted microspots, up to 40 at-% of the implanted hydrogen is not detected, providing support for lateral hydrogen diffusion. Up to 10 16 H-atoms/cm 2 are detected in the near-surface region on all samples, which has not yet been considered in possible mechanisms for creation of ferromagnetism. As theoretical models propose that hydrogen could play a major role in carbon ferromagnetism, this result raises the hypothesis for an effect restricted to the surface. Our preliminary data on magnetic force microscopy of tilted implants show a strong magnetic phase shift localized on the beam entrance point only. (author). 14 refs., 5 figs

  6. Special graphites; Graphites speciaux

    Energy Technology Data Exchange (ETDEWEB)

    Leveque, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    A large fraction of the work undertaken jointly by the Commissariat a l'Energie Atomique (CEA) and the Pechiney Company has been the improvement of the properties of nuclear pile graphite and the opening up of new fields of graphite application. New processes for the manufacture of carbons and special graphites have been developed: forged graphite, pyro-carbons, high density graphite agglomeration of graphite powders by cracking of natural gas, impervious graphites. The physical properties of these products and their reaction with various oxidising gases are described. The first irradiation results are also given. (authors) [French] Ameliorer les proprietes du graphite nucleaire pour empilements et ouvrir de nouveaux domaines d'application au graphite constituent une part importante de l'effort entrepris en commun par le Commissariat a l'Energie Atomique (CEA) et la compagnie PECHINEY. Des procedes nouveaux de fabrication de carbones et graphites speciaux ont ete mis au point: graphite forge, pyrocarbone, graphite de haute densite, agglomeration de poudres de graphite par craquage de gaz naturel, graphites impermeables. Les proprietes physiques de ces produits ainsi que leur reaction avec differents gaz oxydants sont decrites. Les premiers resultats d'irradiation sont aussi donnes. (auteurs)

  7. Nitrogen-Rich Polyacrylonitrile-Based Graphitic Carbons for Hydrogen Peroxide Sensing

    Directory of Open Access Journals (Sweden)

    Brandon Pollack

    2017-10-01

    Full Text Available Catalytic substrate, which is devoid of expensive noble metals and enzymes for hydrogen peroxide (H2O2, reduction reactions can be obtained via nitrogen doping of graphite. Here, we report a facile fabrication method for obtaining such nitrogen doped graphitized carbon using polyacrylonitrile (PAN mats and its use in H2O2 sensing. A high degree of graphitization was obtained with a mechanical treatment of the PAN fibers embedded with carbon nanotubes (CNT prior to the pyrolysis step. The electrochemical testing showed a limit of detection (LOD 0.609 µM and sensitivity of 2.54 µA cm−2 mM−1. The promising sensing performance of the developed carbon electrodes can be attributed to the presence of high content of pyridinic and graphitic nitrogens in the pyrolytic carbons, as confirmed by X-ray photoelectron spectroscopy. The reported results suggest that, despite their simple fabrication, the hydrogen peroxide sensors developed from pyrolytic carbon nanofibers are comparable with their sophisticated nitrogen-doped graphene counterparts.

  8. High temperature gas-cooled reactor (HTGR) graphite pebble fuel: Review of technologies for reprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Mcwilliams, A. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-09-08

    This report reviews literature on reprocessing high temperature gas-cooled reactor graphite fuel components. A basic review of the various fuel components used in the pebble bed type reactors is provided along with a survey of synthesis methods for the fabrication of the fuel components. Several disposal options are considered for the graphite pebble fuel elements including the storage of intact pebbles, volume reduction by separating the graphite from fuel kernels, and complete processing of the pebbles for waste storage. Existing methods for graphite removal are presented and generally consist of mechanical separation techniques such as crushing and grinding chemical techniques through the use of acid digestion and oxidation. Potential methods for reprocessing the graphite pebbles include improvements to existing methods and novel technologies that have not previously been investigated for nuclear graphite waste applications. The best overall method will be dependent on the desired final waste form and needs to factor in the technical efficiency, political concerns, cost, and implementation.

  9. Performances of helium, neon and argon glow discharges for reduction of fuel hydrogen retention in tungsten, stainless steel and graphite

    International Nuclear Information System (INIS)

    Hino, T.; Yamauchi, Y.; Kimura, Y.; Matsumoto, A.; Nishimura, K.; Ueda, Y.

    2012-11-01

    It is quite important to investigate the performance of glow discharge conditionings for controls of in-vessel tritium (T) inventory and hydrogen recycling. For this purpose, first, the deuterium (D) retentions in tungsten (W), graphite (C) and stainless steel (SS) were measured. The retention in W was not small as expected, several times larger than that of SS, although the retention in SS was one order smaller than that of C. Such the large retention in W is owing to the growth of rough surface structure produced by plasma irradiations. For reduction of deuterium retention in W, SS and C, second, inert gas (He, Ne, Ar) glow discharges were conducted under the same condition, and these performances were compared. The removal ratio of deuterium retention was highest in He discharge, and lowest in Ar discharge. These values are well explained by the numerical analyses using SRIM code. The removal ratios for SS and C were significantly large, but quite small for W. This reason is again owing to the rough surface structure in W. For W, thirdly, the hydrogen isotope exchange and the wall baking experiments were conducted. It is found that the wall backing with a temperature higher than 700 K can well reduce the retention, and the hydrogen isotope exchange using deuterium glow discharge is also useful to reduce the tritium retention in the wall. The present results significantly contribute to control the fuel hydrogen retention and to reduce the in-vessel tritium inventory in fusion reactors. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-18

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

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  12. Measurement of dissolved hydrogen and hydrogen gas transfer in a hydrogen-producing reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shizas, I.; Bagley, D.M. [Toronto Univ., ON (Canada). Dept. of Civil Engineering

    2004-07-01

    This paper presents a simple method to measure dissolved hydrogen concentrations in the laboratory using standard equipment and a series of hydrogen gas transfer tests. The method was validated by measuring hydrogen gas transfer parameters for an anaerobic reactor system that was purged with 10 per cent carbon dioxide and 90 per cent nitrogen using a coarse bubble diffuser stone. Liquid samples from the reactor were injected into vials and hydrogen was allowed to partition between the liquid and gaseous phases. The concentration of dissolved hydrogen was determined by comparing the headspace injections onto a gas chromatograph and a standard curve. The detection limit was 1.0 x 10{sup -5} mol/L of dissolved hydrogen. The gas transfer rate for hydrogen in basal medium and anaerobic digester sludge was used to validate the method. Results were compared with gas transfer models. In addition to monitoring dissolved hydrogen in reactor systems, this method can help improve hydrogen production potential. 1 ref., 4 figs.

  13. Quantum dynamics of the Eley-Rideal hydrogen formation reaction on graphite at typical interstellar cloud conditions.

    Science.gov (United States)

    Casolo, Simone; Martinazzo, Rocco; Bonfanti, Matteo; Tantardini, Gian Franco

    2009-12-31

    Eley-Rideal formation of hydrogen molecules on graphite, as well as competing collision induced processes, are investigated quantum dynamically at typical interstellar cloud conditions, focusing in particular on gas-phase temperatures below 100 K, where much of the chemistry of the so-called diffuse clouds takes place on the surface of bare carbonaceous dust grains. Collisions of gas-phase hydrogen atoms with both chemisorbed and physisorbed species are considered using available potential energy surfaces (Sha et al., J. Chem. Phys.2002 116, 7158), and state-to-state, energy-resolved cross sections are computed for a number of initial vibrational states of the hydrogen atoms bound to the surface. Results show that (i) product molecules are internally hot in both cases, with vibrational distributions sharply peaked around few (one or two) vibrational levels, and (ii) cross sections for chemisorbed species are 2-3x smaller than those for physisorbed ones. In particular, we find that H(2) formation cross sections out of chemically bound species decrease steadily when the temperature drops below approximately 1000 K, and this is likely due to a quantum reflection phenomenon. This suggests that such Eley-Rideal reaction is all but efficient in the relevant gas-phase temperature range, even when gas-phase H atoms happen to chemisorb barrierless to the surface as observed, e.g., for forming so-called para dimers. Comparison with results from classical trajectory calculations highlights the need of a quantum description of the dynamics in the astrophysically relevant energy range, whereas preliminary results of an extensive first-principles investigation of the reaction energetics reveal the importance of the adopted substrate model.

  14. Study of new structures adapted to gas-graphite and gas-heavy water reactors

    International Nuclear Information System (INIS)

    Martin, R.; Roche, R.

    1964-01-01

    The experience acquired as a result of the operation of the Marcoule reactors and of the construction and start-up of the E.D.F. reactors on the one hand, and the conclusions of research and tests carried out out-of-pile on the other hand, lead to a considerable change in the general design of reactors of the gas-graphite type. The main modifications envisaged are analysed in the paper. The adoption of an annular fuel element and of a down-current cooling will make it possible to increase considerably the specific power and the power output of each channel; as a result there will be a considerable reduction in the number of the channels and a corresponding increase in the size of the unit cell. The graphite stack will have to be adapted to there new conditions. For security reasons, the use of prestressed concrete for the construction of the reactor vessel is becoming more widespread; they could lead to the exchangers and the fuel-handling apparatus becoming integrated inside the vessel (the so-called 'attic' device). A full-size mode) of this attic has been built at Saclay with the participation of EURATOM; the operational results obtained are presented as well as a new original design for the control rods. As for as the gas-heavy-water system is concerned, the research is carried out on two points of design; the first, which retains the use of horizontal pressure tubes, takes into account the experience acquired during the construction of the EL 4 reactor of which it will constitute an extrapolation; the second, arising from the research carried out on the gas-graphite system, will use a pre-stressed concrete vessel for holding the pressure, the moderator being almost at the same pressure as the cooling fluid and the fuel being placed in vertical channels. The relative merits of these two variants are analysed in the present paper. (authors) [fr

  15. Change of properties after oxidation of IG-11 graphite by air and CO2 gas

    International Nuclear Information System (INIS)

    Lim, Yun-Soo; Chi, Se-Hwan; Cho, Kwang-Yun

    2008-01-01

    Artificial graphite is typically manufactured by carbonization of a shaped body of a kneaded mixture using granular cokes as a filler and pitch as a binder. It undergoes a pitch impregnation process if necessary and finally applying graphitization heat treatment. The effect of thermal oxidation in air or a CO 2 atmosphere on IG-11 graphite samples is investigated in this study. The results show a localized oxidation process that progressively reveals the large coke particles with increasing level of overall weight loss in air. The surface of the graphite was peeled off and no change was found in the specific gravity after air oxidation. However, the specific gravity of graphite was continuously decreased by CO 2 oxidation. The decrease in the specific gravity by CO 2 oxidation was due to CO 2 gas that progressed from the surface to the interior. The pore shape after CO 2 oxidation differed from that under air oxidation

  16. The effect of the partial pressure of H2 gas and atomic hydrogen on diamond films deposited using CH3OH/H2O gas

    International Nuclear Information System (INIS)

    Lee, Kwon-Jai; Koh, Jae-Gui; Shin, Jae-Soo; Kwon, Ki-Hong; Lee, Chang-Hee

    2006-01-01

    Diamond films were deposited on Si(100) substrates by hot filament chemical vapor deposition (HFCVD) with a CH 3 OH/H 2 O gas mixture while changing the gas ratio. The films were analyzed with scanning electron microscopy (SEM), Raman spectroscopy, and optical emission spectroscopy (OES). The diamond films were grown with CH 3 OH being 52 % by volume of the gas mixture. The effect of atomic hydrogen on the film was different from that of the CH 4 /H 2 gas mixture. Analysis with OES during film growth indicated that among the thermally dissociated hydrogen radicals, only H α contributed to the etching of graphite.

  17. On residual gas analysis during high temperature baking of graphite tiles

    International Nuclear Information System (INIS)

    Prakash, A A; Chaudhuri, P; Khirwadkar, S; Reddy, D Chenna; Saxena, Y C; Chauhan, N; Raole, P M

    2008-01-01

    Steady-state Super-conducting Tokamak-1 (SST-1) is a medium size tokamak with major radius of 1.1 m and minor radius of 0.20 m. It is designed for plasma discharge duration of 1000 seconds to obtain fully steady-state plasma operation. Plasma Facing Components (PFC), consisting of divertors, passive stabilizers, baffles and poloidal limiters are also designed to be UHV compatible for steady state operation. All PFC are made up of graphite tiles mechanically attached to the copper alloy substrate. Graphite is one of the preferred first wall armour material in present day tokamaks. High thermal shock resistance and low atomic number of carbon are the most important properties of graphite for this application. High temperature vacuum baking of graphite tiles is the standard process to remove the impurities. Residual Gas Analyzer (RGA) has been used for qualitative and quantitative measurements of released gases from graphite tiles during baking. Surface Analysis of graphite tiles has also been done before and after baking. This paper describes the residual gas analysis during baking and surface analysis of graphite tiles

  18. On residual gas analysis during high temperature baking of graphite tiles

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, A A; Chaudhuri, P; Khirwadkar, S; Reddy, D Chenna; Saxena, Y C [Institute for Plasma Research, Bhat, Gandhinagar - 382 428 (India); Chauhan, N; Raole, P M [Facilitation Center for Industrial Plasma Technologies, IPR, Gandhinagar (India)], E-mail: arun@ipr.res.in

    2008-05-01

    Steady-state Super-conducting Tokamak-1 (SST-1) is a medium size tokamak with major radius of 1.1 m and minor radius of 0.20 m. It is designed for plasma discharge duration of 1000 seconds to obtain fully steady-state plasma operation. Plasma Facing Components (PFC), consisting of divertors, passive stabilizers, baffles and poloidal limiters are also designed to be UHV compatible for steady state operation. All PFC are made up of graphite tiles mechanically attached to the copper alloy substrate. Graphite is one of the preferred first wall armour material in present day tokamaks. High thermal shock resistance and low atomic number of carbon are the most important properties of graphite for this application. High temperature vacuum baking of graphite tiles is the standard process to remove the impurities. Residual Gas Analyzer (RGA) has been used for qualitative and quantitative measurements of released gases from graphite tiles during baking. Surface Analysis of graphite tiles has also been done before and after baking. This paper describes the residual gas analysis during baking and surface analysis of graphite tiles.

  19. Draft of standard for graphite core components in high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Shibata, Taiju; Sawa, Kazuhiro; Eto, Motokuni; Kunimoto, Eiji; Shiozawa, Shusaku; Oku, Tatsuo; Maruyama, Tadashi

    2010-01-01

    For the design of the graphite components in the High Temperature Engineering Test Reactor (HTTR), the graphite structural design code for the HTTR etc. were applied. However, general standard systems for the High Temperature Gas-cooled Reactor (HTGR) have not been established yet. The authors had studied on the technical issues which is necessary for the establishment of a general standard system for the graphite components in the HTGR. The results of the study were documented and discussed at a 'Special committee on research on preparation for codes for graphite components in HTGR' at Atomic Energy Society of Japan (AESJ). As a result, 'Draft of Standard for Graphite Core Components in High Temperature Gas-cooled Reactor.' was established. In the draft standard, the graphite components are classified three categories (A, B and C) in the standpoints of safety functions and possibility of replacement. For the components in the each class, design standard, material and product standards, and in-service inspection and maintenance standard are determined. As an appendix of the design standard, the graphical expressions of material property data of 1G-110 graphite as a function of fast neutron fluence are expressed. The graphical expressions were determined through the interpolation and extrapolation of the irradiated data. (author)

  20. Application of gas chromatography in hydrogen isotope separation

    International Nuclear Information System (INIS)

    Ye Xiaoqiu; Sang Ge; Peng Lixia; Xue Yan; Cao Wei

    2008-01-01

    The principle of gas chromatographic separation of hydrogen isotopes was briefly introduced. The main technology and their development of separating hydrogen isotopes, including elution chromatography, hydrogen-displacement chromatography, self-displacement chromatography and frontal chromatography were discussed in detail. The prospect of hydrogen isotope separation by gas chromatography was presented. (authors)

  1. Special graphites

    International Nuclear Information System (INIS)

    Leveque, P.

    1964-01-01

    A large fraction of the work undertaken jointly by the Commissariat a l'Energie Atomique (CEA) and the Pechiney Company has been the improvement of the properties of nuclear pile graphite and the opening up of new fields of graphite application. New processes for the manufacture of carbons and special graphites have been developed: forged graphite, pyro-carbons, high density graphite agglomeration of graphite powders by cracking of natural gas, impervious graphites. The physical properties of these products and their reaction with various oxidising gases are described. The first irradiation results are also given. (authors) [fr

  2. Advanced High-Temperature Reactor for Production of Electricity and Hydrogen: Molten-Salt-Coolant, Graphite-Coated-Particle-Fuel

    International Nuclear Information System (INIS)

    Forsberg, C.W.

    2002-01-01

    The objective of the Advanced High-Temperature Reactor (AHTR) is to provide the very high temperatures necessary to enable low-cost (1) efficient thermochemical production of hydrogen and (2) efficient production of electricity. The proposed AHTR uses coated-particle graphite fuel similar to the fuel used in modular high-temperature gas-cooled reactors (MHTGRs), such as the General Atomics gas turbine-modular helium reactor (GT-MHR). However, unlike the MHTGRs, the AHTR uses a molten salt coolant with a pool configuration, similar to that of the PRISM liquid metal reactor. A multi-reheat helium Brayton (gas-turbine) cycle, with efficiencies >50%, is used to produce electricity. This approach (1) minimizes requirements for new technology development and (2) results in an advanced reactor concept that operates at essentially ambient pressures and at very high temperatures. The low-pressure molten-salt coolant, with its high heat capacity and natural circulation heat transfer capability, creates the potential for (1) exceptionally robust safety (including passive decay-heat removal) and (2) allows scaling to large reactor sizes [∼1000 Mw(e)] with passive safety systems to provide the potential for improved economics

  3. Extensive Atrophic Gastritis Increases Intraduodenal Hydrogen Gas

    Directory of Open Access Journals (Sweden)

    Yoshihisa Urita

    2008-01-01

    Full Text Available Objective. Gastric acid plays an important part in the prevention of bacterial colonization of the gastrointestinal tract. If these bacteria have an ability of hydrogen (H2 fermentation, intraluminal H2 gas might be detected. We attempted to measure the intraluminal H2 concentrations to determine the bacterial overgrowth in the gastrointestinal tract. Patients and methods. Studies were performed in 647 consecutive patients undergoing upper endoscopy. At the time of endoscopic examination, we intubated the stomach and the descending part of the duodenum without inflation by air, and 20 mL of intraluminal gas samples of both sites was collected through the biopsy channel. Intraluminal H2 concentrations were measured by gas chromatography. Results. Intragastric and intraduodenal H2 gas was detected in 566 (87.5% and 524 (81.0% patients, respectively. The mean values of intragastric and intraduodenal H2 gas were 8.5±15.9 and 13.2±58.0 ppm, respectively. The intraduodenal H2 level was increased with the progression of atrophic gastritis, whereas the intragastric H2 level was the highest in patients without atrophic gastritis. Conclusions. The intraduodenal hydrogen levels were increased with the progression of atrophic gastritis. It is likely that the influence of hypochlorhydria on bacterial overgrowth in the proximal small intestine is more pronounced, compared to that in the stomach.

  4. The Effect of Hydrogen on the Mechanical Properties of Cast Irons and ADI with Various Carbon Equivalent and Graphite Morphology

    International Nuclear Information System (INIS)

    Cho, Yong Gi; Lee, Kyung Sub

    1989-01-01

    The effect of hydrogen on the mechanical properties of cast irons, flake, CV graphite cast iron ductile iron and ADI have been investigated. The effects of various carbon equivalent, graphite morphology and matrix have been analyzed to determine the predominant factor which influences on the hydrogen embrittlement. The effect of various carbon equivalent on the embrittlement was little in the similar graphite morphology. The embrittlement of ferrite matrix changed by heat treatment was less than that of pearlite matrix. In the case of ADI, the tendency of hydrogen embrittlement of lower bainite matrix was less remarkable than that of upper banite matrix. As the result of hydrogen charging, the tendency of interface decohesion between matrix-graphite was increased in flake G.C.I., and the trend from ductile fracture mode to brittle fracture mode was observed in CV G.C.I and ductile iron. Lower bainite in ADI showed the ductile fracture mode. Hydrogen solubility of lower bainite was higher than that of upper bainite

  5. Hydrogen storage in carbon nanofibres for defence applications : the influence of growth parameters on graphitic quality and storage capacity

    Energy Technology Data Exchange (ETDEWEB)

    Turpin, M.; Mellor, I. [Morgan Materials Technology Ltd., Worcestershire (United Kingdom); Shatwell, R.A.; Prentice, C. [QinetiQ Farnborough, Hampshire (United Kingdom); Browning, D.J. [QinetiQ Haslar, Gosport, Hampshire (United Kingdom); Lakeman, J.B. [Dstl Portsdown, Cosham, Hampshire (United Kingdom); Gerrard, M.L.; Mortimer, R.J. [Loughborough Univ. of Technology, Loughborough, Leicestershire (United Kingdom). Dept. of Chemistry

    2002-07-01

    The results of a study on hydrogen storage in carbon or graphite nanofibres (GNFs) were presented. Graphite nanofibres used in hydrogen storage treatment were synthesized at 600 degrees C by passing ethylene over a series of Fe:Ni:Cu catalysts. It was shown that while hydrogen storage can occur for up to 6.5 wt per cent, this number can vary depending on the method of preparation and heat treatment. Hydrogen storage requires an effective method, such as Raman spectroscopy, for characterising the product. Transmission Electron Microscopy also helped in the optimisation of the process to produce highly graphitic nanofibres. The main role of heat treatment is to remove carbon from the surface of the GNFs, allowing access to the graphene planes. Hydrogen storage experiments were conducted at 120 bar, using a bespoke apparatus with differential pressure. A detailed error analysis was performed on the uptake measurement system. The rate of penetration by hydrogen into a layer of carbon capping graphene planes is found to be negligible. It is concluded that hydrogen adsorption will not be observed unless the layer is removed. A maximum uptake of 4.2 wt per cent was achieved, increasing to more than 6.5 wt per cent following heat treatment at 1000 degrees C. 32 refs., 3 tabs., 7 figs.

  6. Graphite and carbon/carbon components for hot gas ducts

    International Nuclear Information System (INIS)

    Popp, G.; Gruber, U.; Boeder, H.; Janssen, K.

    1984-01-01

    The large coal reserves in the Federal Republic of Germany and the uncertainty of the future energy situation on the world market make it appear sound policy to devote some thought to the gasification of coal. For certain chemical processes, moreover, it would be advantageous to have a reasonably priced source of process heat available. In the Federal Republic of Germany this process heat shall be produced in a high-temperature nuclear reactor (HTR), the primary heating temperatures being in the range between 950 deg. C and 1050 deg. C. One serious problem in utilisation of high temperature heat is the resistance of the construction materials. Ceramic materials with high temperature resistance are considered. The material includes graphite and CC carbon fibre reinforced carbon. As a result of the project promoted by Ministerium fur Wirtschaft (Federal Republic of Germany) it has been demonstrated that both CC and graphite manufactured by SIGRI GmbH are well suited for use in high temperature reactors

  7. Advanced IGCC/Hydrogen Gas Turbine Development

    Energy Technology Data Exchange (ETDEWEB)

    York, William [General Electric Company, Schenectady, NY (United States); Hughes, Michael [General Electric Company, Schenectady, NY (United States); Berry, Jonathan [General Electric Company, Schenectady, NY (United States); Russell, Tamara [General Electric Company, Schenectady, NY (United States); Lau, Y. C. [General Electric Company, Schenectady, NY (United States); Liu, Shan [General Electric Company, Schenectady, NY (United States); Arnett, Michael [General Electric Company, Schenectady, NY (United States); Peck, Arthur [General Electric Company, Schenectady, NY (United States); Tralshawala, Nilesh [General Electric Company, Schenectady, NY (United States); Weber, Joseph [General Electric Company, Schenectady, NY (United States); Benjamin, Marc [General Electric Company, Schenectady, NY (United States); Iduate, Michelle [General Electric Company, Schenectady, NY (United States); Kittleson, Jacob [General Electric Company, Schenectady, NY (United States); Garcia-Crespo, Andres [General Electric Company, Schenectady, NY (United States); Delvaux, John [General Electric Company, Schenectady, NY (United States); Casanova, Fernando [General Electric Company, Schenectady, NY (United States); Lacy, Ben [General Electric Company, Schenectady, NY (United States); Brzek, Brian [General Electric Company, Schenectady, NY (United States); Wolfe, Chris [General Electric Company, Schenectady, NY (United States); Palafox, Pepe [General Electric Company, Schenectady, NY (United States); Ding, Ben [General Electric Company, Schenectady, NY (United States); Badding, Bruce [General Electric Company, Schenectady, NY (United States); McDuffie, Dwayne [General Electric Company, Schenectady, NY (United States); Zemsky, Christine [General Electric Company, Schenectady, NY (United States)

    2015-07-30

    The objective of this program was to develop the technologies required for a fuel flexible (coal derived hydrogen or syngas) gas turbine for IGCC that met DOE turbine performance goals. The overall DOE Advanced Power System goal was to conduct the research and development (R&D) necessary to produce coal-based IGCC power systems with high efficiency, near-zero emissions, and competitive capital cost. To meet this goal, the DOE Fossil Energy Turbine Program had as an interim objective of 2 to 3 percentage points improvement in combined cycle (CC) efficiency. The final goal is 3 to 5 percentage points improvement in CC efficiency above the state of the art for CC turbines in IGCC applications at the time the program started. The efficiency goals were for NOx emissions of less than 2 ppm NOx (@15 % O2). As a result of the technologies developed under this program, the DOE goals were exceeded with a projected 8 point efficiency improvement. In addition, a new combustion technology was conceived of and developed to overcome the challenges of burning hydrogen and achieving the DOE’s NOx goal. This report also covers the developments under the ARRA-funded portion of the program that include gas turbine technology advancements for improvement in the efficiency, emissions, and cost performance of gas turbines for industrial applications with carbon capture and sequestration. Example applications could be cement plants, chemical plants, refineries, steel and aluminum plants, manufacturing facilities, etc. The DOE’s goal for more than 5 percentage point improvement in efficiency was met with cycle analyses performed for representative IGCC Steel Mill and IGCC Refinery applications. Technologies were developed in this program under the following areas: combustion, larger latter stage buckets, CMC and EBC, advanced materials and coatings, advanced configurations to reduce cooling, sealing and rotor purge flows, turbine aerodynamics, advanced sensors, advancements in first

  8. Promoted Ru on high-surface area graphite for efficient miniaturized production of hydrogen from ammonia

    DEFF Research Database (Denmark)

    Sørensen, Rasmus Zink; Klerke, Asbjørn; Quaade, Ulrich

    2006-01-01

    decomposition. The catalytic activities for production of hydrogen from ammonia are determined for different promoters and promoter levels on graphite supported ruthenium catalysts. The reactivity trends of the Ru/C catalysts promoted with Cs and Ba are in excellent agreement with those known from earlier......Promoted Ru/C catalysts for decomposition of ammonia are incorporated into micro-fabricated reactors for the first time. With the reported preparation technique, the performance is increased more than two orders of magnitude compared to previously known micro-fabricated reactors for ammonia...... studies of both ammonia synthesis and decomposition, and it is shown how proper promotion can facilitate ammonia decomposition at temperatures below 500 K....

  9. Graphite fuels combustion off-gas treatment options

    International Nuclear Information System (INIS)

    Kirkham, R.J.; Lords, R.E.

    1993-03-01

    Scenarios for burning bulk graphite and for burning crushed fuel particles from graphite spent nuclear fuels have been considered. Particulates can be removed with sintered metal filters. Subsequent cooling would then condense semi-volatile fission products into or onto a particulate. These particulates would be trapped by a second sintered metal filter or downstream packed bed. A packed bed scrub column can be used to eliminate most of the iodine-129 and tritium. A molecular sieve bed is proposed to collect the residual 129 I and other tramp radionuclides downstream (Ruthenium, etc.). Krypton-85 can be recovered, if need be, either by cryogenics or by the KALC process (Krypton Adsorption in Liquid Carbon dioxide). Likewise carbon-14 in the form of carbon dioxide could be collected with a caustic or lime scrub solution and incorporated into a grout. Sulfur dioxide present will be well below regulatory concern level of 4.0 tons per year and most of it would be removed by the scrubber. Carbon monoxide emissions will depend on the choice of burner and start-up conditions. Should the system exceed the regulatory concern level, a catalytic converter in the final packed bed will be provided. Radon and its daughters have sufficiently short half-lives (less than two minutes). If necessary, an additional holdup bed can be added before the final HEPA filters or additional volume can be added to the molecular sieve bed to limit radon emissions. The calculated total effective dose equivalent at the Idaho National Engineering Laboratory boundary from a single release of all the 3 , 14 C, 85 Kr, and 129 I in the total fuel mass if 0.43 mrem/year

  10. Hydrogen-Enhanced Natural Gas Vehicle Program

    Energy Technology Data Exchange (ETDEWEB)

    Hyde, Dan; Collier, Kirk

    2009-01-22

    The project objective is to demonstrate the viability of HCNG fuel (30 to 50% hydrogen by volume and the remainder natural gas) to reduce emissions from light-duty on-road vehicles with no loss in performance or efficiency. The City of Las Vegas has an interest in alternative fuels and already has an existing hydrogen refueling station. Collier Technologies Inc (CT) supplied the latest design retrofit kits capable of converting nine compressed natural gas (CNG) fueled, light-duty vehicles powered by the Ford 5.4L Triton engine. CT installed the kits on the first two vehicles in Las Vegas, trained personnel at the City of Las Vegas (the City) to perform the additional seven retrofits, and developed materials for allowing other entities to perform these retrofits as well. These vehicles were used in normal service by the City while driver impressions, reliability, fuel efficiency and emissions were documented for a minimum of one year after conversion. This project has shown the efficacy of operating vehicles originally designed to operate on compressed natural gas with HCNG fuel incorporating large quantities of exhaust gas recirculation (EGR). There were no safety issues experienced with these vehicles. The only maintenance issue in the project was some rough idling due to problems with the EGR valve and piping parts. Once the rough idling was corrected no further maintenance issues with these vehicles were experienced. Fuel economy data showed no significant changes after conversion even with the added power provided by the superchargers that were part of the conversions. Driver feedback for the conversions was very favorable. The additional power provided by the HCNG vehicles was greatly appreciated, especially in traffic. The drivability of the HCNG vehicles was considered to be superior by the drivers. Most of the converted vehicles showed zero oxides of nitrogen throughout the life of the project using the State of Nevada emissions station.

  11. Analytic description of the chemical erosion of graphite by hydrogen ions

    International Nuclear Information System (INIS)

    Roth, J.; Garcia-Rosales, C.

    1996-01-01

    One main concern about the use of graphite as a plasma facing material is the enhanced erosion, under hydrogen bombardment due to hydrocarbon formation. In view of the lifetime evaluation of plasma exposed carbon components and of impurity production in present and future machines such as ITER, an analytical expression for the erosion yield by chemical sputtering for the relevant energies, temperatures and incident fluxes is of special importance. An extrapolation to fluxes and energies relevant for high density divertor plasmas has not been possible up to now on the basis of semiempirical fits to laboratory data. Starting from a short review of the existing empirical formulas, recent detailed investigations of the atomistic processes for the thermally activated hydrocarbon emission are described, which enable the formulation of an improved analytical description including the ion flux as a parameter. The chemical erosion of graphite by hydrogen bombardment results from two processes: the thermally activated hydrocarbon emission, Y therm , and a surface process at low energies and low temperatures resulting from the kinetic ejection of surface hydrocarbon complexes from collisional energy transfer, Y surf . The new analytic description can be fitted well to the existing data for ion beam erosion, and extrapolation to divertor relevant fluxes is possible. At high ion fluxes the maximum of chemical erosion is shifted to higher temperatures, where annealing of damaged structures leads to a stronger reduction of Y therm than previously estimated. There are no data on a possible flux dependence of Y surf , leaving still some uncertainty in extrapolation. (author). 46 refs, 10 figs, 1 tab

  12. Deuterium migration in nuclear graphite: consequences for the behavior of tritium in Gas Cooled Reactors and for the decontamination of irradiated graphite waste

    International Nuclear Information System (INIS)

    Le-Guillou, Mael

    2014-01-01

    In France, 23 000 t of irradiated graphite that will be generated by the decommissioning of the first generation Uranium Naturel-Graphite-Gaz (UNGG) nuclear reactors are waiting for a long term management solution. This work focuses on the behavior of tritium, which is one of the main contributors to the radiological inventory of graphite waste after reactor shutdown. In order to anticipate tritium release during dismantling or waste management, it is mandatory to collect data on its migration, location and inventory. Our study is based on the simulation of tritium by implantation of approximately 3 at. % of deuterium up to around 3 μm in a virgin nuclear graphite. This material was then annealed up to 300 h and 1300 C in inert atmosphere, UNGG coolant gas and humid gas, aiming to reproduce thermal conditions close to those encountered in reactor and during waste management operations. The deuterium profiles and spatial distribution were analyzed using the nuclear reaction 2 H( 3 He,p) 4 He. The main results evidence a thermal release of implanted deuterium occurring essentially through three regimes controlled by the detrapping of atomic deuterium located in superficial or interstitial sites. The extrapolation of our data to tritium suggests that its purely thermal release during reactor operations may have been lower than 30 % and would be located close to the graphite free surfaces. Consequently, most of the tritium inventory after reactor shutdown could be trapped deeply within the irradiated graphite structure. Decontamination of graphite waste should then require temperatures higher than 1300 C, and would be more efficient in dry inert gas than in humid gas. (author)

  13. Investigation of Pristine Graphite Oxide as Room-Temperature Chemiresistive Ammonia Gas Sensing Material

    Directory of Open Access Journals (Sweden)

    Alexander G. Bannov

    2017-02-01

    Full Text Available Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammonia in a gas phase. Graphite oxide was synthesized from high purity graphite using the modified Hummers method. The graphite oxide sample was investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetry and differential scanning calorimetry. Sensing properties were tested in a wide range of ammonia concentrations in air (10–1000 ppm and under different relative humidity levels (3%–65%. It was concluded that the graphite oxide–based sensor possessed a good response to NH3 in dry synthetic air (ΔR/R0 ranged from 2.5% to 7.4% for concentrations of 100–500 ppm and 3% relative humidity with negligible cross-sensitivity towards H2 and CH4. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing the ambient relative humidity led to an increase of the sensor response. The highest response of 22.2% for 100 ppm of ammonia was achieved at a 65% relative humidity level.

  14. Impact of hydrogen insertion on vehicular natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Strangueto, Karina Maretti; Silva, Ennio Peres da [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. of Mechanical Engineering. Energy Dept.], Email: karinakms@fem.unicamp.br

    2010-07-01

    This article aims to analyze the possibility of insertion of hydrogen in the vehicular natural gas or even the insertion of the hydrogen in the compressed natural gas used in Brazil. For the production of this hydrogen, the spilled turbinable energy from Itaipu would be harnessed. The calculation of production can be extended to other power plants which are close to the natural gas pipelines, where the hydrogen would be introduced. Then, it was analyzed the consumption of natural gas in vehicles in Brazil, the regulation of transportation, the sales of compressed natural gas to fuelling station, the specifications that the piped gas should follow to be sold, and how much hydrogen could be accepted in the mix. (author)

  15. Gas-chromatographic separation of hydrogen isotopic mixtures

    International Nuclear Information System (INIS)

    Preda, Anisoara; Bidica, Nicolae

    2005-01-01

    Full text: Gas chromatographic separation of hydrogen isotopes have been reported in the literature since late of 1950's. Gas chromatography is primarily an analytical method, but because of its properties it may be used in many other fields with excellent results. A simple method is proposed for the gas-chromatographic analysis of complex gas mixtures containing hydrogen isotopes; the method is based on the substantial difference in the thermal conductivity of these isotopes. One of the main disadvantages of the conventional gas chromatography is the long retention times required for the analysis of hydrogen gas mixtures while the column is operated at very low temperature. The method described in this paper was based on using a capillary molecular sieve 5A column operated for this kind of separation at 173 K. The carrier gas was Ne and the detector was TCD. In the paper chromatograms for various carrier flow rates and various hydrogen isotope mixtures are presented. (authors)

  16. The status of graphite development for gas cooled reactors

    International Nuclear Information System (INIS)

    1993-02-01

    The meeting was convened by the IAEA on the recommendation of the International Working Group on Gas Cooled Reactors. It was attended by 61 participants from 6 countries. The meeting covered the following subjects: overview of national programs; design criteria, fracture mechanisms and component test; materials development and properties; non-destructive examination, inspection and surveillance. The participants presented 33 papers on behalf of their countries. A separate abstract was prepared for each of these papers. Refs, figs, tabs, photos and diagrams

  17. A solution to level 3 dismantling of gas-cooled reactors: Graphite incineration

    International Nuclear Information System (INIS)

    Dubourg, M.

    1993-01-01

    This paper presents an approach developed to solve the specific decommissioning problems of the G2 and G3 gas cooled reactors at Marcoule and the strategy applied with emphasis in incinerating the graphite core components, using a fluidized-bed incinerator developed jointly between the CEA and FRAMATOME. The incineration option was selected over subsurface storage for technical and economic reasons. Studies have shown that gaseous incineration releases are environmentally acceptable

  18. Disintegration of graphite matrix from the simulative high temperature gas-cooled reactor fuel element by electrochemical method

    International Nuclear Information System (INIS)

    Tian Lifang; Wen Mingfen; Li Linyan; Chen Jing

    2009-01-01

    Electrochemical method with salt as electrolyte has been studied to disintegrate the graphite matrix from the simulative high temperature gas-cooled reactor fuel elements. Ammonium nitrate was experimentally chosen as the appropriate electrolyte. The volume average diameter of disintegrated graphite fragments is about 100 μm and the maximal value is less than 900 μm. After disintegration, the weight of graphite is found to increase by about 20% without the release of a large amount of CO 2 probably owing to the partial oxidation to graphite in electrochemical process. The present work indicates that the improved electrochemical method has the potential to reduce the secondary nuclear waste and is a promising option to disintegrate graphite matrix from high temperature gas-cooled reactor spent fuel elements in the head-end of reprocessing.

  19. Studies on synthesis and hydrogenation behaviour of graphitic nanofibres prepared through palladium catalyst assisted thermal cracking of acetylene

    International Nuclear Information System (INIS)

    Gupta, Bipin Kumar; Tiwari, R.S.; Srivastava, O.N.

    2004-01-01

    The nano-variants of carbon including graphitic nanofibres (GNF) have recently been considered to be exotic (light weight, high storage capacity) hydrogen storage materials. In the present paper, we report growth of aligned bundles of GNF. The length and width of cross-section of the bundles is ∼50 and ∼25 μm, respectively. The length of individual GNF is ∼50 μm and diameter ∼0.25 μm. The GNFs have been synthesized through thermal decomposition of acetylene using palladium (Pd) sheets as catalyst. This represents a new form of catalyst. The GNFs bundles grown by the present method are easier to hydrogenate. They adsorb hydrogen at a lower pressure of ∼80 atm as against ∼120 atm for the GNF grown in the earlier studies. The storage capacity obtained in the present investigation is ∼17 wt.%. Electron microscopic investigations reveal that as against the as grown GNF, the hydrogenated version embodies microstructures exhibiting fragmentation of graphitic layer bundles. The reasons for the growth of GNF in the form of aligned bundles, the ease of hydrogenation and relevance of GNF fragmentation after hydrogenation have been outlined

  20. Studies on synthesis and hydrogenation behaviour of graphitic nanofibres prepared through palladium catalyst assisted thermal cracking of acetylene

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Bipin Kumar; Tiwari, R.S.; Srivastava, O.N

    2004-11-03

    The nano-variants of carbon including graphitic nanofibres (GNF) have recently been considered to be exotic (light weight, high storage capacity) hydrogen storage materials. In the present paper, we report growth of aligned bundles of GNF. The length and width of cross-section of the bundles is {approx}50 and {approx}25 {mu}m, respectively. The length of individual GNF is {approx}50 {mu}m and diameter {approx}0.25 {mu}m. The GNFs have been synthesized through thermal decomposition of acetylene using palladium (Pd) sheets as catalyst. This represents a new form of catalyst. The GNFs bundles grown by the present method are easier to hydrogenate. They adsorb hydrogen at a lower pressure of {approx}80 atm as against {approx}120 atm for the GNF grown in the earlier studies. The storage capacity obtained in the present investigation is {approx}17 wt.%. Electron microscopic investigations reveal that as against the as grown GNF, the hydrogenated version embodies microstructures exhibiting fragmentation of graphitic layer bundles. The reasons for the growth of GNF in the form of aligned bundles, the ease of hydrogenation and relevance of GNF fragmentation after hydrogenation have been outlined.

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

    Science.gov (United States)

    Stephens, H.P.

    1986-06-05

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

  2. Role of a natural gas utility in the hydrogen economy

    International Nuclear Information System (INIS)

    Bayko, J.

    2004-01-01

    'Full text:' Enbridge Gas Distribution is the largest natural gas distribution company in Canada at about 1.7 million residential, commercial and industrial customers. Enbridge will speak to the role of a natural gas utility in the hydrogen economy, and outline the benefits of hydrogen production from natural gas reformation for both stationary and mobile applications. Hydrocarbon reformation will act at least as a bridge until a more fully developed hydrogen economy infrastructure is developed. Reformation allows immediate leveraging of the reliability of vast existing natural gas distribution systems, and a reduced need for on-site hydrogen storage. Natural gas powered fuel cells provide improved emissions over traditional internal combustion engines, and in the stationary market provide smarter use of resources through the higher efficiencies of cogeneration (the capture and use of otherwise waste heat). (author)

  3. Feasibility study of hydrogen determination in blended gas mixture by an indigenously developed hydrogen determinator

    International Nuclear Information System (INIS)

    Gaikwad, Revati; Sonar, V.R.; Pandey, R.K.; Karekar, C.D.; Raul, Seema; Mahanty, B.; Kelkar, A.; Bhatt, R.B.; Behere, P.G.

    2017-01-01

    It is required to determine accurately the percentage composition of hydrogen in the blended gas of N 2 and H 2 prior to deliver to the sintering furnace. A feasibility study has been carried out to determine the percentage composition of hydrogen in the blended gas by using an indigenously developed hydrogen determinator. The instrument uses gas chromatograph-thermal conductivity (GC-TCD) technique to determine hydrogen. The flow of carrier gas was kept at 100 mL min -1 during the analysis. A very close agreement between the determined value and the reported value of hydrogen content in the commercially available N 2 -H 2 mixed cylinder was found by using the indigenous hydrogen determinator. (author)

  4. Catalase-Based Modified Graphite Electrode for Hydrogen Peroxide Detection in Different Beverages

    Directory of Open Access Journals (Sweden)

    Giovanni Fusco

    2016-01-01

    Full Text Available A catalase-based (NAF/MWCNTs nanocomposite film modified glassy carbon electrode for hydrogen peroxide (H2O2 detection was developed. The developed biosensor was characterized in terms of its bioelectrochemical properties. Cyclic voltammetry (CV technique was employed to study the redox features of the enzyme in the absence and in the presence of nanomaterials dispersed in Nafion® polymeric solution. The electron transfer coefficient, α, and the electron transfer rate constant, ks, were found to be 0.42 and 1.71 s−1, at pH 7.0, respectively. Subsequently, the same modification steps were applied to mesoporous graphite screen-printed electrodes. Also, these electrodes were characterized in terms of their main electrochemical and kinetic parameters. The biosensor performances improved considerably after modification with nanomaterials. Moreover, the association of Nafion with carbon nanotubes retained the biological activity of the redox protein. The enzyme electrode response was linear in the range 2.5–1150 μmol L−1, with LOD of 0.83 μmol L−1. From the experimental data, we can assess the possibility of using the modified biosensor as a useful tool for H2O2 determination in packaged beverages.

  5. Atomic and molecular hydrogen gas temperatures in a low-pressure helicon plasma

    Science.gov (United States)

    Samuell, Cameron M.; Corr, Cormac S.

    2015-08-01

    Neutral gas temperatures in hydrogen plasmas are important for experimental and modelling efforts in fusion technology, plasma processing, and surface modification applications. To provide values relevant to these application areas, neutral gas temperatures were measured in a low pressure (radiofrequency helicon discharge using spectroscopic techniques. The atomic and molecular species were not found to be in thermal equilibrium with the atomic temperature being mostly larger then the molecular temperature. In low power operation (measurements near a graphite target demonstrated localised cooling near the sample surface. The temporal evolution of the molecular gas temperature during a high power 1.1 ms plasma pulse was also investigated and found to vary considerably as a function of pressure.

  6. Development Of A Centrifugal Hydrogen Pipeline Gas Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Di Bella, Francis A. [Concepts NREC, White River Junction, VY (United States)

    2015-04-16

    Concepts NREC (CN) has completed a Department of Energy (DOE) sponsored project to analyze, design, and fabricate a pipeline capacity hydrogen compressor. The pipeline compressor is a critical component in the DOE strategy to provide sufficient quantities of hydrogen to support the expected shift in transportation fuels from liquid and natural gas to hydrogen. The hydrogen would be generated by renewable energy (solar, wind, and perhaps even tidal or ocean), and would be electrolyzed from water. The hydrogen would then be transported to the population centers in the U.S., where fuel-cell vehicles are expected to become popular and necessary to relieve dependency on fossil fuels. The specifications for the required pipeline hydrogen compressor indicates a need for a small package that is efficient, less costly, and more reliable than what is available in the form of a multi-cylinder, reciprocating (positive displacement) compressor for compressing hydrogen in the gas industry.

  7. On-Board Hydrogen Gas Production System For Stirling Engines

    Science.gov (United States)

    Johansson, Lennart N.

    2004-06-29

    A hydrogen production system for use in connection with Stirling engines. The production system generates hydrogen working gas and periodically supplies it to the Stirling engine as its working fluid in instances where loss of such working fluid occurs through usage through operation of the associated Stirling engine. The hydrogen gas may be generated by various techniques including electrolysis and stored by various means including the use of a metal hydride absorbing material. By controlling the temperature of the absorbing material, the stored hydrogen gas may be provided to the Stirling engine as needed. A hydrogen production system for use in connection with Stirling engines. The production system generates hydrogen working gas and periodically supplies it to the Stirling engine as its working fluid in instances where loss of such working fluid occurs through usage through operation of the associated Stirling engine. The hydrogen gas may be generated by various techniques including electrolysis and stored by various means including the use of a metal hydride absorbing material. By controlling the temperature of the absorbing material, the stored hydrogen gas may be provided to the Stirling engine as needed.

  8. Method of removing hydrogen sulphide from hot gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Furimsky, E.; Yumura, M.

    1987-12-22

    Hydrogen sulphide can be removed from hot gas mixtures by contacting the hot gas mixture at temperatures in the range of 500-900/sup 0/C with an adsorbent consisting of managanese nodules. The nodules may contain additional calcium cations. In sulphided form, the nodules are catalytically active for hydrogen sulphide decomposition to produce hydrogen. Regeneration of the adsorbent can be accomplished by roasting in an oxidizing atmosphere. The nodules can be used to treat gaseous mixtures containing up to 20% hydrogen sulfide, for example, gases produced during pyrolysis, cracking, coking, and hydrotreating processes. Experiments using the processes described in this patent are also outlined. 6 tabs.

  9. Microwave interaction with nonuniform hydrogen gas in carbon nanotubes

    International Nuclear Information System (INIS)

    Babaei, S.; Babaei, Sh.

    2009-01-01

    In this paper we study the reflection, absorption, and transmission of microwave from nonuniform hydrogen gas in carbon nanotubes, grown by iron-catalyzed high-pressure carbon monoxide disproportionate (HiPco) process. A discussion on the effect of various hydrogen gas parameters on the reflected power, absorbed power, and transmitted power is presented. The nonuniform hydrogen gas slab is modeled by a series of subslabs. The overall number density profile across the whole slab follows a parabolic function. The total reflected, absorbed, and transmitted powers are then deduced and their functional dependence on the number density, collision frequency, and angle of propagation is studied

  10. Device to remove hydrogen isotopes from a gas phase

    International Nuclear Information System (INIS)

    Morlock, G.; Wiesemes, J.; Bachner, D.

    1977-01-01

    The device described here guarantees the selective removal of hydrogen isotopes from gas phases in order to prevent the occurence of explosive H 2 gas mixtures, or to separate off radioactive tritium in nuclear plants from the gas phase. It consists of a closed container whose walls are selectively penetrable by hydrogen isotopes. It is simultaneously filled compactly and presssure-resistant with a metal bulk (e.g. powder, sponges or the like of titanium or other hydrogen isotope binding metal). Walling and bulk are maintained at suitable working temperatures by means of a system according to the Peltier effect. The whole thing is safeguarded by protective walling. (RB) [de

  11. Condensation in gas transmission pipelines. Phase behavior of mixtures of hydrogen with natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Schouten, J.A.; Michels, J.P.J. [Amsterdam Univ. (Netherlands). Van der Waals-Zeeman Inst.; Rosmalen, R.J. van [Energy, Roden (Netherlands)

    2005-05-01

    Several pressure and temperature reductions occur along gas transmission lines. Since the pressure and temperature conditions of the natural gas in the pipeline are often close to the dew point curve, liquid dropout can occur. Injection of hydrogen into the natural gas will change the phase envelope and thus the liquid dropout. This condensation of the heavy hydrocarbons requires continuous operational attention and a positive effect of hydrogen may affect the decision to introduce hydrogen. In this paper we report on calculations of the amount of condensate in a natural gas and in this natural gas mixed with 16.7% hydrogen. These calculations have been performed at conditions prevailing in gas transport lines. The results will be used to discuss the difference in liquid dropout in a natural gas and in a mixture with hydrogen at pressure reduction stations, at crossings under waterways, at side-branching, and at separators in the pipelines. (author)

  12. Adsorption process to recover hydrogen from feed gas mixtures having low hydrogen concentration

    Science.gov (United States)

    Golden, Timothy Christopher; Weist, Jr., Edward Landis; Hufton, Jeffrey Raymond; Novosat, Paul Anthony

    2010-04-13

    A process for selectively separating hydrogen from at least one more strongly adsorbable component in a plurality of adsorption beds to produce a hydrogen-rich product gas from a low hydrogen concentration feed with a high recovery rate. Each of the plurality of adsorption beds subjected to a repetitive cycle. The process comprises an adsorption step for producing the hydrogen-rich product from a feed gas mixture comprising 5% to 50% hydrogen, at least two pressure equalization by void space gas withdrawal steps, a provide purge step resulting in a first pressure decrease, a blowdown step resulting in a second pressure decrease, a purge step, at least two pressure equalization by void space gas introduction steps, and a repressurization step. The second pressure decrease is at least 2 times greater than the first pressure decrease.

  13. Process for the production of hydrogen/deuterium-containing gas

    International Nuclear Information System (INIS)

    Nitschke, E.; Desai, A.; Ilgner, H.

    1978-01-01

    A process for the production of hydrogen/deuterium-containing gas is described in which the enriched condensate obtained from the production of a hydrogen/deuterium-containing gas mixture is collected and subjected to a direct exchange of isotopes with the feedsteam admitted to the process. Such condensate can be brought into direct exchange of isotopes with the gas water vapor mixture within the process, viz. ahead of the CO conversion section. The exchange of isotopes may be performed according to the counter-current principle. If it is intended to maintain in the hydrogen/deuterium-containing gas a certain definite content of water vapor whose phase condition is superior to the condition achieved when using normal cooling water, this gas, at least 0.6 kg/m 3 of gas, is subjected to an exchange of isotopes with the water fed additionally into the process

  14. Constitutive modeling and finite element procedure development for stress analysis of prismatic high temperature gas cooled reactor graphite core components

    International Nuclear Information System (INIS)

    Mohanty, Subhasish; Majumdar, Saurindranath; Srinivasan, Makuteswara

    2013-01-01

    Highlights: • Finite element procedure developed for stress analysis of HTGR graphite component. • Realistic fluence profile and reflector brick shape considered for the simulation. • Also realistic H-451 grade material properties considered for simulation. • Typical outer reflector of a GT-MHR type reactor considered for numerical study. • Based on the simulation results replacement of graphite bricks can be scheduled. -- Abstract: High temperature gas cooled reactors, such as prismatic and pebble bed reactors, are increasingly becoming popular because of their inherent safety, high temperature process heat output, and high efficiency in nuclear power generation. In prismatic reactors, hexagonal graphite bricks are used as reflectors and fuel bricks. In the reactor environment, graphite bricks experience high temperature and neutron dose. This leads to dimensional changes (swelling and or shrinkage) of these bricks. Irradiation dimensional changes may affect the structural integrity of the individual bricks as well as of the overall core. The present paper presents a generic procedure for stress analysis of prismatic core graphite components using graphite reflector as an example. The procedure is demonstrated through commercially available ABAQUS finite element software using the option of user material subroutine (UMAT). This paper considers General Atomics Gas Turbine-Modular Helium Reactor (GT-MHR) as a bench mark design to perform the time integrated stress analysis of a typical reflector brick considering realistic geometry, flux distribution and realistic irradiation material properties of transversely isotropic H-451 grade graphite

  15. Constitutive modeling and finite element procedure development for stress analysis of prismatic high temperature gas cooled reactor graphite core components

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish, E-mail: smohanty@anl.gov [Argonne National Laboratory, South Cass Avenue, Argonne, IL 60439 (United States); Majumdar, Saurindranath [Argonne National Laboratory, South Cass Avenue, Argonne, IL 60439 (United States); Srinivasan, Makuteswara [U.S. Nuclear Regulatory Commission, Washington, DC 20555 (United States)

    2013-07-15

    Highlights: • Finite element procedure developed for stress analysis of HTGR graphite component. • Realistic fluence profile and reflector brick shape considered for the simulation. • Also realistic H-451 grade material properties considered for simulation. • Typical outer reflector of a GT-MHR type reactor considered for numerical study. • Based on the simulation results replacement of graphite bricks can be scheduled. -- Abstract: High temperature gas cooled reactors, such as prismatic and pebble bed reactors, are increasingly becoming popular because of their inherent safety, high temperature process heat output, and high efficiency in nuclear power generation. In prismatic reactors, hexagonal graphite bricks are used as reflectors and fuel bricks. In the reactor environment, graphite bricks experience high temperature and neutron dose. This leads to dimensional changes (swelling and or shrinkage) of these bricks. Irradiation dimensional changes may affect the structural integrity of the individual bricks as well as of the overall core. The present paper presents a generic procedure for stress analysis of prismatic core graphite components using graphite reflector as an example. The procedure is demonstrated through commercially available ABAQUS finite element software using the option of user material subroutine (UMAT). This paper considers General Atomics Gas Turbine-Modular Helium Reactor (GT-MHR) as a bench mark design to perform the time integrated stress analysis of a typical reflector brick considering realistic geometry, flux distribution and realistic irradiation material properties of transversely isotropic H-451 grade graphite.

  16. Production yields of noble-gas isotopes from ISOLDE UC$_{x}$/graphite targets

    CERN Document Server

    Bergmann, U C; Catherall, R; Cederkäll, J; Diget, C A; Fraile-Prieto, L M; Franchoo, S; Fynbo, H O U; Gausemel, H; Georg, U; Giles, T; Hagebø, E; Jeppesen, H B; Jonsson, O C; Köster, U; Lettry, Jacques; Nilsson, T; Peräjärvi, K; Ravn, H L; Riisager, K; Weissman, L; Äystö, J

    2003-01-01

    Yields of He, Ne, Ar, Kr and Xe isotopic chains were measured from UC$_{x}$/graphite and ThC$_{x}$/graphite targets at the PSB-ISOLDE facility at CERN using isobaric selectivity achieved by the combination of a plasma-discharge ion source with a water-cooled transfer line. %The measured half-lives allowed %to calculate the decay losses of neutron-rich isotopes in the %target and ion-source system, and thus to obtain information on the in-target %productions from the measured yields. The delay times measured for a UC$_x$/graphite target allow for an extrapolation to the expected yields of very neutron-rich noble gas isotopes, in particular for the ``NuPECC reference elements'' Ar and Kr, at the next-generation radioactive ion-beam facility EURISOL. \\end{abstract} \\begin{keyword} % keywords here, in the form: keyword \\sep keyword radioactive ion beams \\sep release \\sep ion yields \\sep ISOL (Isotope Separation On-Line) \\sep uranium and thorium carbide targets. % PACS codes here, in the form: \\PACS code \\sep code...

  17. Analysis of graphite dust deposition in hot gas duct of HTGR

    International Nuclear Information System (INIS)

    Peng Wei; Zhen Ya'nan; Yang Xiaoyong; Ye Ping

    2013-01-01

    The behavior of the graphite dust is important to the safety of high-temperature gas-cooled reactor (HTGR). The temperature field in hot gas duct was obtained using computational fluid dynamics (CFD) method. Further analysis to the thermo-phoretic deposition and turbulent deposition shows that as the dust particle diameter increases, the thermo-phoretic deposition efficiency decreases, and the turbulent deposition efficiency initially decreases and then increases. The comparisons of calculation results for two reactor powers, namely 30% FP (full power) and 100 % FP, indicate that the thermo-phoretic deposition efficiency is higher at 30% FP than that at 100% FP. while the turbulent deposition efficiency grows more rapidly at 100% FP. Besides, the results also demonstrate that the thermo-phoretic deposition and the turbulent deposition are nearly equivalent when particle sizes are small, while the turbulent deposition becomes dominant when particle sizes are fairly large. The calculation results by using the most probable distribution of particle size show that the total deposition of graphite dusts in hot gas duct is limited. (authors)

  18. Methane generated from graphite--tritium interaction

    International Nuclear Information System (INIS)

    Coffin, D.O.; Walthers, C.R.

    1979-01-01

    When hydrogen isotopes are separated by cryogenic distillation, as little as 1 ppM of methane will eventually plug the still as frost accumulates on the column packings. Elemental carbon exposed to tritium generates methane spontaneously, and yet some dry transfer pumps, otherwise compatible with tritium, convey the gas with graphite rotors. This study was to determine the methane production rate for graphite in tritium. A pump manufacturer supplied graphite samples that we exposed to tritium gas at 0.8 atm. After 137 days we measured a methane synthesis rate of 6 ng/h per cm 2 of graphite exposed. At this rate methane might grow to a concentration of 0.01 ppM when pure tritium is transferred once through a typical graphite--rotor transfer pump. Such a low methane level will not cause column blockage, even if the cryogenic still is operated continuously for many years

  19. Method to Assess the Radionuclide Inventory of Irradiated Graphite from Gas-Cooled Reactors - 13072

    Energy Technology Data Exchange (ETDEWEB)

    Poncet, Bernard [EDF-CIDEN, 154 Avenue Thiers, CS 60018, F-69458 LYON cedex 06 (France)

    2013-07-01

    About 17,000 t of irradiated graphite waste will be produced from the decommissioning of the six French gas-cooled nuclear reactors. Determining the radionuclide (RN) content of this waste is of relevant importance for safety reasons and in order to determine the best way to manage them. For many reasons the impurity content that gave rise to the RNs in irradiated graphite by neutron activation during operation is not always well known and sometimes actually unknown. So, assessing the RN content by the use of traditional calculation activation, starting from assumed impurity content, leads to a false assessment. Moreover, radiochemical measurements exhibit very wide discrepancies especially on RN corresponding to precursor at the trace level such as natural chlorine corresponding to chlorine 36. This wide discrepancy is unavoidable and is due to very simple reasons. The level of impurity is very low because the uranium fuel used at that very moment was not enriched, so it was a necessity to have very pure nuclear grade graphite and the very low size of radiochemical sample is a simple technical constraint because device size used to get mineralization product for measurement purpose is limited. The assessment of a radionuclide inventory only based on few number of radiochemical measurements lead in most cases, to a gross over or under-estimation that is detrimental for graphite waste management. A method using an identification calculation-measurement process is proposed in order to assess a radiological inventory for disposal sizing purpose as precise as possible while guaranteeing its upper character. This method present a closer approach to the reality of the main phenomenon at the origin of RNs in a reactor, while also incorporating the secondary effects that can alter this result such as RN (or its precursor) release during reactor operation. (authors)

  20. Energy evaluations, graphite corrosion in Bugey I

    International Nuclear Information System (INIS)

    Brisbois, J.; Fiche, C.

    1967-01-01

    Bugey I presents a problem of radiolytic corrosion of the graphite by the CO 2 under pressure at high temperature. This report aims to evaluate the energy transferred to the gas by a Bugey I core cell, in normal operating conditions. The water, the carbon oxides and the hydrogen formed quantities are deduced as the consumed graphite and methane. Experimental studies are realized in parallel to validate the presented results. (A.L.B.)

  1. Individual hollow and mesoporous aero-graphitic microtube based devices for gas sensing applications

    Science.gov (United States)

    Lupan, Oleg; Postica, Vasile; Marx, Janik; Mecklenburg, Matthias; Mishra, Yogendra K.; Schulte, Karl; Fiedler, Bodo; Adelung, Rainer

    2017-06-01

    In this work, individual hollow and mesoporous graphitic microtubes were integrated into electronic devices using a FIB/SEM system and were investigated as gas and vapor sensors by applying different bias voltages (in the range of 10 mV-1 V). By increasing the bias voltage, a slight current enhancement is observed, which is mainly attributed to the self-heating effect. A different behavior of ammonia NH3 vapor sensing by increasing the applied bias voltage for hollow and mesoporous microtubes with diameters down to 300 nm is reported. In the case of the hollow microtube, an increase in the response was observed, while a reverse effect has been noticed for the mesoporous microtube. It might be explained on the basis of the higher specific surface area (SSA) of the mesoporous microtube compared to the hollow one. Thus, at room temperature when the surface chemical reaction rate (k) prevails on the gas diffusion rate (DK) the structures with a larger SSA possess a higher response. By increasing the bias voltage, i.e., the overall temperature of the structure, DK becomes a limiting step in the gas response. Therefore, at higher bias voltages the larger pores will facilitate an enhanced gas diffusion, i.e., a higher gas response. The present study demonstrates the importance of the material porosity towards gas sensing applications.

  2. Hydrogen gas getters: Susceptibility to poisoning

    International Nuclear Information System (INIS)

    Mroz, E.J.; Dye, R.C.; Duke, J.R.; Weinrach, J.

    1998-01-01

    About 40% (∼9,000) of the ∼23,000 transuranic (TRU) waste drums at Los Alamos National Laboratory (LANL) are presently unshippable because conservative calculations suggest that the hydrogen concentration may exceed the lower explosive limit for hydrogen. This situation extends across nearly all DOE sites holding and generating TRU waste. The incorporation of a hydrogen getter such as DEB into the waste drums (or the TRUPACT II shipping containers) could substantially mitigate the explosion risk. The result would be to increase the number of drums that qualify for transportation to the Waste Isolation Pilot Plant (WIPP) without having to resort to expensive re-packaging or waste treatment technologies. However, before this approach can be implemented, key technical questions must be answered. Foremost among these is the question of whether the presence of other chemical vapors and gases in the drum might poison the catalytic reaction between hydrogen and DEB. This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to obtain fundamental information on the chemical mechanism of the catalytic reaction of hydrogen with one commonly used hydrogen getter, DEB. Experiments with these materials showed that the method of exposure affects the nature of the reaction products. The results of this work contributed to the development of a mechanistic model of the reaction

  3. Determination of hydrogen in zirconium hydride and uranium-zirconium hydride by inert gas exraction-gravimetric method

    International Nuclear Information System (INIS)

    Hoshino, Akira; Iso, Shuichi

    1976-01-01

    An inert gas extraction-gravimetric method has been applied to the determination of hydrogen in zirconium hydride and uranium-zirconium hydride which are used as neutron moderator and fuel of nuclear safety research reactor (NSRR), respectively. The sample in a graphite-enclosed quartz crucible is heated inductively to 1200 0 C for 20 min in a helium stream. Hydrogen liberated from the sample is oxidized to water by copper(I) oxide-copper(II) oxide at 400 0 C, and the water is determined gravimetrically by absorption in anhydrone. The extraction curves of hydrogen for zirconium hydride and uranium-zirconium hydride samples are shown in Figs. 2 and 3. Hydrogen in the samples is extracted quantitatively by heating at (1000 -- 1250) 0 C for (10 -- 40) min. Recoveries of hydrogen in the case of zirconium hydride were examined as follows: a weighed zirconium rod (5 phi x 6 mm, hydrogen -5 Torr. After the chamber was filled with purified hydrogen to 200 Torr, the rod was heated to 400 0 C for 15 h, and again weighed to determine the increase in weight. Hydrogen in the rod was then determined by the proposed method. The results are in excellent agreement with the increase in weight as shown in Table 1. Analytical results of hydrogen in zirconium hydride samples and an uranium-zirconium hydride sample are shown in Table 2. (auth.)

  4. Oxidation damage evaluation by non-destructive method for graphite components in high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Shibata, Taiju; Tada, Tatsuya; Sumita, Junya; Sawa, Kazuhiro

    2008-01-01

    To develop non-destructive evaluation methods for oxidation damage on graphite components in High Temperature Gas-cooled Reactors (HTGRs), the applicability of ultrasonic wave and micro-indentation methods were investigated. Candidate graphites, IG-110 and IG-430, for core components of Very High Temperature Reactor (VHTR) were used in this study. These graphites were oxidized uniformly by air at 500degC. The following results were obtained from this study. (1) Ultrasonic wave velocities with 1 MHz can be expressed empirically by exponential formulas to burn-off, oxidation weight loss. (2) The porous condition of the oxidized graphite could be evaluated with wave propagation analysis with a wave-pore interaction model. It is important to consider the non-uniformity of oxidized porous condition. (3) Micro-indentation method is expected to determine the local oxidation damage. It is necessary to assess the variation of the test data. (author)

  5. Visible-light-enhanced interactions of hydrogen sulfide with composites of zinc (oxy)hydroxide with graphite oxide and graphene.

    Science.gov (United States)

    Seredych, Mykola; Mabayoje, Oluwaniyi; Bandosz, Teresa J

    2012-01-17

    Composites of zinc(oxy)hydroxide-graphite oxide and of zinc(oxy)hydroxide-graphene were used as adsorbents of hydrogen sulfide under ambient conditions. The initial and exhausted samples were characterized by XRD, FTIR, potentiometric titration, EDX, thermal analysis, and nitrogen adsorption. An increase in the amount of H(2)S adsorbed/oxidized on their surfaces in comparison with that of pure Zn(OH)(2) is linked to the structure of the composite, the relative number of terminal hydroxyls, and the kind of graphene-based phase used. Although terminal groups are activated by a photochemical process, the graphite oxide component owing to the chemical bonds with the zinc(oxy)hydroxide phase and conductive properties helps in electron transfer, leading to more efficient oxygen activation via the formation of superoxide ions. Elemental sulfur, zinc sulfide, sulfite, and sulfate are formed on the surface. The formation of sulfur compounds on the surface of zinc(oxy)hydroxide during the course of the breakthrough experiments and thus Zn(OH)(2)-ZnS heterojunctions can also contribute to the increased surface activity of our materials. The results show the superiority of graphite oxide in the formation of composites owing to its active surface chemistry and the possibility of interface bond formation, leading to an increase in the number of electron-transfer reactions. © 2011 American Chemical Society

  6. Adsorption of hydrogen gas and redox processes in clays.

    Science.gov (United States)

    Didier, Mathilde; Leone, Laura; Greneche, Jean-Marc; Giffaut, Eric; Charlet, Laurent

    2012-03-20

    In order to assess the adsorption properties of hydrogen gas and reactivity of adsorbed hydrogen, we measured H(2)(g) adsorption on Na synthetic montmorillonite-type clays and Callovo-Oxfordian (COx) clayrock using gas chromatography. Synthetic montmorillonites with increasing structural Fe(III) substitution (0 wt %, 3.2 wt %, and 6.4 wt % Fe) were used. Fe in the synthetic montmorillonites is principally present as structural Fe(III) ions. We studied the concomitant reduction of structural Fe(III) in the clays using (57)Fe Mössbauer spectrometry. The COx, which mainly contains smectite/illite and calcite minerals, is also studied together with the pure clay fraction of this clayrock. Experiments were performed with dry clay samples which were reacted with hydrogen gas at 90 and 120 °C for 30 to 45 days at a hydrogen partial pressure close to 0.45 bar. Results indicate that up to 0.11 wt % of hydrogen is adsorbed on the clays at 90 °C under 0.45 bar of relative pressure. (57)Fe Mössbauer spectrometry shows that up to 6% of the total structural Fe(III) initially present in these synthetic clays is reduced upon adsorption of hydrogen gas. No reduction is observed with the COx sample in the present experimental conditions.

  7. Spatial flux instabilities, and their control in the graphite gas power reactors; Les instabilites spatiales du flux et leur controle dans les reacteurs de puissance graphite-gaz

    Energy Technology Data Exchange (ETDEWEB)

    Cailly, J L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Radial-azimuthal and axial spatial flux instabilities in graphite-gas reactors are studied by means of an analytical approach. Results are checked with those which are given by two dimensional (r, z and r, {theta}) kinetic models programmed for an IBM 7094 computer. At least, conclusions on the control of instabilities obtained from these models are reported. (author) [French] Les instabilites spatiales du flux dans les reacteurs graphite-gaz, radiales et azimutales d'une part, axiales d'autre part, sont etudiees au moyen d'une formulation analytique. Les resultats sont confrontes avec ceux que fournissent des modeles cinetiques a deux dimensions (r, z et r, {theta}) programmes sur IBM 7094. On donne enfin les conclusions relatives au controle de ces instabilites que ces modeles ont permis de degager. (auteur)

  8. Improved Hydrogen Gas Getters for TRU Waste -- Final Report

    International Nuclear Information System (INIS)

    Mark Stone; Michael Benson; Christopher Orme; Thomas Luther; Eric Peterson

    2005-01-01

    Alpha radiolysis of hydrogenous waste and packaging materials generates hydrogen gas in radioactive storage containers. For that reason, the Nuclear Regulatory Commission limits the flammable gas (hydrogen) concentration in the Transuranic Package Transporter-II (TRUPACT-II) containers to 5 vol% of hydrogen in air, which is the lower explosion limit. Consequently, a method is needed to prevent the build up of hydrogen to 5 vol% during the storage and transport of the TRUPACT-II containers (up to 60 days). One promising option is the use of hydrogen getters. These materials scavenge hydrogen from the gas phase and irreversibly bind it in the solid phase. One proven getter is a material called 1,4-bis (phenylethynyl) benzene, or DEB, characterized by the presence of carbon-carbon triple bonds. Carbon may, in the presence of suitable precious metal catalysts such as palladium, irreversibly react with and bind hydrogen. In the presence of oxygen, the precious metal may also eliminate hydrogen by catalyzing the formation of water. This reaction is called catalytic recombination. DEB has the needed binding rate and capacity for hydrogen that potentially could be generated in the TRUPACT II. Phases 1 and 2 of this project showed that uncoated DEB performed satisfactorily in lab scale tests. Based upon these results, Phase 3, the final project phase, included larger scale testing. Test vessels were scaled to replicate the ratio between void space in the inner containment vessel of a TRUPACT-II container and a payload of seven 55-gallon drums. The tests were run with an atmosphere of air for 63.9 days at ambient temperature (15-27 C) and a scaled hydrogen generation rate of 2.60E-07 moles per second (0.35 cc/min). A second type of getter known as VEI, a proprietary polymer hydrogen getter characterized by carbon-carbon double bonds, was also tested in Phase 3. Hydrogen was successfully ''gettered'' by both getter systems. Hydrogen concentrations remained below 5 vol% (in

  9. Improved Hydrogen Gas Getters for TRU Waste -- Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Mark Stone; Michael Benson; Christopher Orme; Thomas Luther; Eric Peterson

    2005-09-01

    Alpha radiolysis of hydrogenous waste and packaging materials generates hydrogen gas in radioactive storage containers. For that reason, the Nuclear Regulatory Commission limits the flammable gas (hydrogen) concentration in the Transuranic Package Transporter-II (TRUPACT-II) containers to 5 vol% of hydrogen in air, which is the lower explosion limit. Consequently, a method is needed to prevent the build up of hydrogen to 5 vol% during the storage and transport of the TRUPACT-II containers (up to 60 days). One promising option is the use of hydrogen getters. These materials scavenge hydrogen from the gas phase and irreversibly bind it in the solid phase. One proven getter is a material called 1,4-bis (phenylethynyl) benzene, or DEB, characterized by the presence of carbon-carbon triple bonds. Carbon may, in the presence of suitable precious metal catalysts such as palladium, irreversibly react with and bind hydrogen. In the presence of oxygen, the precious metal may also eliminate hydrogen by catalyzing the formation of water. This reaction is called catalytic recombination. DEB has the needed binding rate and capacity for hydrogen that potentially could be generated in the TRUPACT II. Phases 1 and 2 of this project showed that uncoated DEB performed satisfactorily in lab scale tests. Based upon these results, Phase 3, the final project phase, included larger scale testing. Test vessels were scaled to replicate the ratio between void space in the inner containment vessel of a TRUPACT-II container and a payload of seven 55-gallon drums. The tests were run with an atmosphere of air for 63.9 days at ambient temperature (15-27°C) and a scaled hydrogen generation rate of 2.60E-07 moles per second (0.35 cc/min). A second type of getter known as VEI, a proprietary polymer hydrogen getter characterized by carbon-carbon double bonds, was also tested in Phase 3. Hydrogen was successfully “gettered” by both getter systems. Hydrogen concentrations remained below 5 vol% (in

  10. Interactions of hydrogen with graphite at low pressure and elevated temperature

    International Nuclear Information System (INIS)

    Hoinkis, E.

    1991-03-01

    The plasma facing components of the vacuum chamber for thermonuclear fusion experiments are clad with graphite. Recycling of gases affects the plasma properties, and the tritium quantity accumulated in the graphite during the operation of Tokamaks with DT must be known. An adsorption isotherm for deuterium on the nuclear grade graphitic Matrix A3-3 was measured by using a volumetric method at 1173 K at pressures c = 2.5 eV/D 2 using Fowler's equation and isotherms were calculated for this E c value. These isotherms predict saturation of the adsorption sites in graphite at T D2 > 0.1 Pa. At T > 1173 K and P D2 -2 Pa the adsorbed quantity is less than 1% of the saturation level. The release kinetics of deuterium was measured at temperatures uo to 2000 K. D 2 desorption commenced at 1170 K. The maximum of the release rate is observed at T p = 1770 K. A Lennard-Jones potential energy diagram was calculated, which suggests a C-H bond energy E b ≅ 3.4 eV/D and an activation energy of desorption E d ≅ 4 eV/D 2 . The partial pressures of hydrocarbons C n ≤3 H m in equilibrium with graphite were calculated. At total pressures -2 Pa the partial pressures of these hydrocarbons are less than 10 -7 Pa in the temperature range 600-1500 K. (orig./MM)

  11. Study of the strength of the internal can for internally and externally cooled fuel elements intended for gas graphite reactors

    International Nuclear Information System (INIS)

    Boudouresque, B.; Courcon, P.; Lestiboubois, G.

    1964-01-01

    The cartridge of an internally and externally cooled annular fuel element used in gas-graphite reactors is made up of an uranium fuel tube, an external can and an internal can made of magnesium alloy. For the thermal exchange between the internal can and the fuel to be satisfactory, it is necessary for the can to stay in contact with the uranium under all temperature conditions. This report, based on a theoretical study, shows how the internal can fuel gap varies during the processes of canning, charging into the reactor and thermal cycling. The following parameters are considered: tube diameter, pressure of the heat carrying gas, gas entry temperature, plasticity of the can alloy. It is shown that for all operating conditions the internal can of a 77 x 95 element, planned for a gas-graphite reactor with a 40 kg/cm 2 gas pressure, should remain in contact with the fuel. (authors) [fr

  12. Enhanced reactive adsorption of hydrogen sulfide on the composites of graphene/graphite oxide with copper (hydr)oxychlorides.

    Science.gov (United States)

    Mabayoje, Oluwaniyi; Seredych, Mykola; Bandosz, Teresa J

    2012-06-27

    Composites of copper (hydr)oxychlorides with graphite oxide or graphene were synthesized and used as adsorbents of hydrogen sulfide at dynamic conditions at ambient temperatures. The materials were extensively characterized before and after adsorption in order to link their performance to the surface features. X-ray diffraction, FTIR, thermal analysis, TEM, SEM/EDX, and adsorption of nitrogen were used. It was found that the composite with graphene has the most favorable surface features enhancing reactive adsorption of hydrogen sulfide. The presence of moisture in the H2S stream has a positive effect on the removal process owing to the dissociation process. H2S is retained on the surface via a direct replacement of OH groups and via acid-base reactions with the copper (hydr)oxide. Highly dispersed reduced copper species on the surface of the composite with graphene enhance activation of oxygen and cause formation of sulfites and sulfates. Higher conductivity of the graphene phase than that of graphite oxide helps in electron transfer in redox reactions.

  13. Ultrathin nitrogen-doped graphitized carbon shell encapsulating CoRu bimetallic nanoparticles for enhanced electrocatalytic hydrogen evolution

    Science.gov (United States)

    Xu, You; Li, Yinghao; Yin, Shuli; Yu, Hongjie; Xue, Hairong; Li, Xiaonian; Wang, Hongjing; Wang, Liang

    2018-06-01

    Design of highly active and cost-effective electrocatalysts is very important for the generation of hydrogen by electrochemical water-splitting. Herein, we report the fabrication of ultrathin nitrogen-doped graphitized carbon shell encapsulating CoRu bimetallic nanoparticles (CoRu@NCs) and demonstrate their promising feasibility for efficiently catalyzing the hydrogen evolution reaction (HER) over a wide pH range. The resultant CoRu@NC nanohybrids possess an alloy–carbon core–shell structure with encapsulated low-ruthenium-content CoRu bimetallic alloy nanoparticles (10–30 nm) as the core and ultrathin nitrogen-doped graphitized carbon layers (2–6 layers) as the shell. Remarkably, the optimized catalyst (CoRu@NC-2 sample) with a Ru content as low as 2.04 wt% shows superior catalytic activity and excellent durability for HER in acidic, neutral, and alkaline conditions. This work offers a new method for the design and synthesis of non-platium-based electrocatalysts for HER in all-pH.

  14. Studies of Reduced Graphene Oxide and Graphite Oxide in the Aspect of Their Possible Application in Gas Sensors

    Science.gov (United States)

    Drewniak, Sabina; Muzyka, Roksana; Stolarczyk, Agnieszka; Pustelny, Tadeusz; Kotyczka-Morańska, Michalina; Setkiewicz, Maciej

    2016-01-01

    The paper presents the results of investigations on resistance structures based on graphite oxide (GRO) and graphene oxide (rGO). The subject matter of the investigations was thaw the sensitivity of the tested structures was affected by hydrogen, nitrogen dioxide and carbon dioxide. The experiments were performed at a temperature range from 30 °C to 150 °C in two carrier gases: nitrogen and synthetic air. The measurements were also aimed at characterization of the graphite oxide and graphene oxide. In our measurements we used (among others) techniques such as: Atomic Force Microscopy (AFM); Scanning Electron Microscopy (SEM); Raman Spectroscopy (RS); Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Microscopy (XPS). The data resulting from the characterizations of graphite oxide and graphene oxide have made it possible to interpret the obtained results from the point of view of physicochemical changes occurring in these structures. PMID:26784198

  15. Studies of Reduced Graphene Oxide and Graphite Oxide in the Aspect of Their Possible Application in Gas Sensors.

    Science.gov (United States)

    Drewniak, Sabina; Muzyka, Roksana; Stolarczyk, Agnieszka; Pustelny, Tadeusz; Kotyczka-Morańska, Michalina; Setkiewicz, Maciej

    2016-01-15

    The paper presents the results of investigations on resistance structures based on graphite oxide (GRO) and graphene oxide (rGO). The subject matter of the investigations was thaw the sensitivity of the tested structures was affected by hydrogen, nitrogen dioxide and carbon dioxide. The experiments were performed at a temperature range from 30 °C to 150 °C in two carrier gases: nitrogen and synthetic air. The measurements were also aimed at characterization of the graphite oxide and graphene oxide. In our measurements we used (among others) techniques such as: Atomic Force Microscopy (AFM); Scanning Electron Microscopy (SEM); Raman Spectroscopy (RS); Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Microscopy (XPS). The data resulting from the characterizations of graphite oxide and graphene oxide have made it possible to interpret the obtained results from the point of view of physicochemical changes occurring in these structures.

  16. The behaviour of CAGR moderator and sleeve graphites radiolytically oxidised to high weight loss in inhibited coolant gas compositions

    International Nuclear Information System (INIS)

    Schofield, P.; Fitzgerald, B.; Ketchen, J.

    1987-01-01

    Gilsocarbon graphites were irradiated to high weight losses in three different CO 2 based coolants. The experimental data is tested against a model which interprets the gas phase chemistry and pore geometry and allows weight loss and gas flow properties to be calculated. The observed changes of oxidation rate with dose were successfully predicted from the model. An empirical relationship was also derived which was shown to fit data for moderator, sleeve and special pore structure graphites. Changes in graphite permeability and diffusivity were predicted by the model, and also by other simplified, more approximate methods. The model based upon the measured transport pore spectrum was shown to be the best with other methods proving adequate to moderate doses. (author)

  17. Hydrogen Gas Production in a Stand-Alone Wind Farm

    Directory of Open Access Journals (Sweden)

    M. Naziry Kordkandy

    2017-04-01

    Full Text Available This paper is analyzing the operation of a stand-alone wind farm with variable speed turbines, permanent magnet synchronous generators (PMSG and a system for converting wind energy during wind speed variations. On this paper, the design and modeling of a wind system which uses PMSG’s to provide the required power of a hydrogen gas electrolyzer system, is discussed. This wind farm consists of three wind turbines, boost DC-DC converters, diode full bridge rectifiers, permanent magnet synchronous generators, MPPT control and a hydrogen gas electrolyzer system. The MPPT controller based on fuzzy logic is designed to adjust the duty ratio of the boost DC-DC converters to absorb maximum power. The proposed fuzzy logic controller assimilates, with (PSF MPPT algorithm which generally used to absorb maximum power from paralleled wind turbines and stores it in form of hydrogen gas. The system is modeled and its behavior is studied using the MATLAB software.

  18. Transport of a relativistic electron beam through hydrogen gas

    International Nuclear Information System (INIS)

    Haan, P. de.

    1981-01-01

    In this thesis the author describes the transport properties of an electron beam through vacuum and through hydrogen gas with pressure ranging from 25 to 1000 Pa. Maximum beam energy and current are 0.8 MeV and 6 kA, respectively. The pulse length is around 150 ns. A description is given of the experimental device. Also the diagnostics for probing the beam and the plasma, produced by the beam, are discussed, as well as the data acquisition system. The interaction between the beam and hydrogen gas with a pressure around 200 Pa is considered. A plasma with density around 10 19 m -3 is produced within a few nanoseconds. Measurements yield the atomic hydrogen temperature, electron density, beam energy loss, and induced plasma current and these are compared with the results of a model combining gas ionization and dissociation, and turbulent plasma heating. The angular distribution of the beam electrons about the magnetic field axis is discussed. (Auth.)

  19. Blending Hydrogen into Natural Gas Pipeline Networks. A Review of Key Issues

    Energy Technology Data Exchange (ETDEWEB)

    Melaina, M. W. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Antonia, O. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Penev, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2013-03-01

    This study assesses the potential to deliver hydrogen through the existing natural gas pipeline network as a hydrogen and natural gas mixture to defray the cost of building dedicated hydrogen pipelines. Blending hydrogen into the existing natural gas pipeline network has also been proposed as a means of increasing the output of renewable energy systems such as large wind farms.

  20. Hydrogen Gas as a Fuel in Direct Injection Diesel Engine

    Science.gov (United States)

    Dhanasekaran, Chinnathambi; Mohankumar, Gabriael

    2016-04-01

    Hydrogen is expected to be one of the most important fuels in the near future for solving the problem caused by the greenhouse gases, for protecting environment and saving conventional fuels. In this study, a dual fuel engine of hydrogen and diesel was investigated. Hydrogen was conceded through the intake port, and simultaneously air and diesel was pervaded into the cylinder. Using electronic gas injector and electronic control unit, the injection timing and duration varied. In this investigation, a single cylinder, KIRLOSKAR AV1, DI Diesel engine was used. Hydrogen injection timing was fixed at TDC and injection duration was timed for 30°, 60°, and 90° crank angles. The injection timing of diesel was fixed at 23° BTDC. When hydrogen is mixed with inlet air, emanation of HC, CO and CO2 decreased without any emission (exhaustion) of smoke while increasing the brake thermal efficiency.

  1. Production of bioplastics and hydrogen gas by photosynthetic microorganisms

    Science.gov (United States)

    Yasuo, Asada; Masato, Miyake; Jun, Miyake

    1998-03-01

    Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium, Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilic Synechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes from Alcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted. In vitro and in vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation of Synechococcus PCC7942 with the hydrogenase gene from Clostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture of Rhodobacter and Clostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium, Rhodobacter sphaeroides RV. A mutant acquired by

  2. Gas storage materials, including hydrogen storage materials

    Science.gov (United States)

    Mohtadi, Rana F; Wicks, George G; Heung, Leung K; Nakamura, Kenji

    2013-02-19

    A material for the storage and release of gases comprises a plurality of hollow elements, each hollow element comprising a porous wall enclosing an interior cavity, the interior cavity including structures of a solid-state storage material. In particular examples, the storage material is a hydrogen storage material such as a solid state hydride. An improved method for forming such materials includes the solution diffusion of a storage material solution through a porous wall of a hollow element into an interior cavity.

  3. Magnetic resonance studies of atomic hydrogen gas at low temperatures

    International Nuclear Information System (INIS)

    Hardy, W.N.; Morrow, M.; Jochemsen, R.; Statt, B.W.; Kubik, P.R.; Marsolais, R.M.; Berlinsky, A.J.; Landesman, A.

    1980-01-01

    Using a pulsed low temperature discharge in a closed cell containing H 2 and 4 He, we have been able to store a low density (approximately 10 12 atoms/cc) gas of atomic hydrogen for periods of order one hour in zero magnetic field and T=1 K. Pulsed magnetic resonance at the 1420 MHz hyperfine transition has been used to study a number of the properties of the gas, including the recombination rate H + H + 4 He→H 2 + 4 He, the hydrogen spin-exchange relaxation rates, the diffusion coefficient of H in 4 He gas and the pressure shift of the hyperfine frequency due to the 4 He buffer gas. Here we discuss the application of hyperfine frequency shifts as a probe of the H-He potential, and as a means for determining the binding energy of H on liquid helium

  4. Blending Hydrogen into Natural Gas Pipeline Networks: A Review of Key Issues

    Energy Technology Data Exchange (ETDEWEB)

    Melaina, M. W.; Antonia, O.; Penev, M.

    2013-03-01

    The United States has 11 distinct natural gas pipeline corridors: five originate in the Southwest, four deliver natural gas from Canada, and two extend from the Rocky Mountain region. This study assesses the potential to deliver hydrogen through the existing natural gas pipeline network as a hydrogen and natural gas mixture to defray the cost of building dedicated hydrogen pipelines.

  5. Field test of hydrogen in the natural gas grid

    Energy Technology Data Exchange (ETDEWEB)

    Iskov, H

    2010-08-15

    In order to prepare for a future use of hydrogen as a fuel gas it became evident that very little information existed regarding the compatibility between long-term exposure and transportation of hydrogen in natural gas pipelines. A program was therefore set to study the transportation in a small-scale pilot grid at the research centre in Hoersholm, Denmark. The test program included steel pipes from the Danish gas transmission grid and polymer pipes from the Danish and Swedish gas distribution grid. The test of polymer pipes was devised so that samples of all test pipes were cut out of the grid each year and analysis performed on these pipe samples; in this way any form of influence on the integrity of the polyethylene pipe would be detected. The analytical program for polymer was devised in order to detect any influence on the additivation of the polyethylene as this has an influence on oxidative resistance, as well as checking already encountered possible degradation caused by extrusion of the material. Further tools as rheology and melt flow rate were used for detecting any structural changes on the material. On the mechanical property side the tensile strength and modulus were followed as well as the most important property for the pipe line, namely slow crack growth. The results of the polymer pipe tests show no degradations of any kind related to the continuous hydrogen exposure for more than 4 years. This is a strong indication of the compatibility to hydrogen of the tested polymer materials PE 80 and PE 100. The object of the steel pipe test was to see the effect on fatigue life of existing natural gas transmission lines with hydrogen replacing the natural gas. Full-scale dynamic tests were performed using randomly selected cut-out API 5L X70 pipe sections with a diameter of 20 inches and a wall thickness of 7 millimetres from the Danish natural gas transmission system. The pipe sections contained field girth weld made during the installation of the pipe

  6. Field test of hydrogen in the natural gas grid

    Energy Technology Data Exchange (ETDEWEB)

    Iskov, H.

    2010-08-15

    In order to prepare for a future use of hydrogen as a fuel gas it became evident that very little information existed regarding the compatibility between long-term exposure and transportation of hydrogen in natural gas pipelines. A program was therefore set to study the transportation in a small-scale pilot grid at the research centre in Hoersholm, Denmark. The test program included steel pipes from the Danish gas transmission grid and polymer pipes from the Danish and Swedish gas distribution grid. The test of polymer pipes was devised so that samples of all test pipes were cut out of the grid each year and analysis performed on these pipe samples; in this way any form of influence on the integrity of the polyethylene pipe would be detected. The analytical program for polymer was devised in order to detect any influence on the additivation of the polyethylene as this has an influence on oxidative resistance, as well as checking already encountered possible degradation caused by extrusion of the material. Further tools as rheology and melt flow rate were used for detecting any structural changes on the material. On the mechanical property side the tensile strength and modulus were followed as well as the most important property for the pipe line, namely slow crack growth. The results of the polymer pipe tests show no degradations of any kind related to the continuous hydrogen exposure for more than 4 years. This is a strong indication of the compatibility to hydrogen of the tested polymer materials PE 80 and PE 100. The object of the steel pipe test was to see the effect on fatigue life of existing natural gas transmission lines with hydrogen replacing the natural gas. Full-scale dynamic tests were performed using randomly selected cut-out API 5L X70 pipe sections with a diameter of 20 inches and a wall thickness of 7 millimetres from the Danish natural gas transmission system. The pipe sections contained field girth weld made during the installation of the pipe

  7. Scaled Testing of Hydrogen Gas Getters for Transuranic Waste

    International Nuclear Information System (INIS)

    Kaszuba, J.; Mroz, E.; Haga, M.; Hollis, W. K.; Peterson, E.; Stone, M.; Orme, C.; Luther, T.; Benson, M.

    2006-01-01

    Alpha radiolysis of hydrogenous waste and packaging materials generates hydrogen gas in radioactive storage and shipment containers. Hydrogen forms a flammable mixture with air over a wide range of concentrations (5% to 75%), and very low energy is needed to ignite hydrogen-air mixtures. For these reasons, the concentration of hydrogen in waste shipment containers (Transuranic Package Transporter-II or TRUPACT-II containers) needs to remain below the lower explosion limit of hydrogen in air (5 vol%). Accident scenarios and the resulting safety analysis require that this limit not be exceeded. The use of 'hydrogen getters' is being investigated as a way to prevent the build up of hydrogen in TRUPACT-II containers. Preferred getters are solid materials that scavenge hydrogen from the gas phase and chemically and irreversibly bind it into the solid state. In this study, two getter systems are evaluated: a) 1,4-bis (phenylethynyl)benzene or DEB, characterized by the presence of carbon-carbon triple bonds; and b) a proprietary polymer hydrogen getter, VEI or TruGetter, characterized by carbon-carbon double bonds. Carbon in both getter types may, in the presence of suitable precious metal catalysts such as palladium, irreversibly react with and bind hydrogen. With oxygen present, the precious metal may also eliminate hydrogen by catalyzing the formation of water. This reaction is called catalytic recombination. DEB and VEI performed satisfactorily in lab scale tests using small test volumes (ml-scale), high hydrogen generation rates, and short time spans of hours to days. The purpose of this study is to evaluate whether DEB and VEI perform satisfactorily in actual drum-scale tests with realistic hydrogen generation rates and time frames. The two getter systems were evaluated in test vessels comprised of a Gas Generation Test Program-style bell-jar and a drum equipped with a composite drum filter. The vessels were scaled to replicate the ratio between void space in the

  8. Power to gas. The final breakthrough for the hydrogen economy?

    Energy Technology Data Exchange (ETDEWEB)

    Winkler-Goldstein, Raphael [Germany Trade and Invest (GTAI), Paris (France); Rastetter, Aline [Alphea Hydrogene, Forbach (France)

    2013-04-01

    In Germany more than 20% of the energy mix is made up of renewable energy and its share is rapidly increasing. The federal government expects renewables to account for 35% of Germany's electricity consumption by 2020, 50% by 2030 and 80% by 2050. According to the German Energy Agency, multi-billion euro investments in energy storage are expected by 2020 in order to reach these goals. The growth of this fluctuating energy supply has created demand for innovative storage options in Germany and it is accelerating the development of technologies in this field. Along with batteries and smart grids, hydrogen is expected to be one of the lead technologies. 2010 a commercialization roadmap for wind hydrogen was set up by the two northern federal states of Hamburg and Schleswig-Holstein with the goal of utilizing surplus wind power for the electrolytic production of hydrogen. With the creation of the 'performing energy initiative', 2011, Brandenburg and Lower Saxony joined this undertaking. The aim of this initiative is to set up demonstration projects in order to develop and optimize wind-hydrogen hybrid systems and prepare their commercialization for the time after 2020. Beside the conversion of hydrogen into electricity and fuel for cars, further markets like raw material for the chemical, petrochemical, metallurgy and food industry are going to be addressed. Considering the fact there are over 40 caves currently used for natural gas storage with a total volume of 23.5 billion cubic meters and 400 000 km gas grid available in Germany, the German Technical and Scientific Association for Gas and Water sees opportunities for hydrogen to be fed into the existing natural gas grid network. The name of this concept is power-to-gas. According to the current DVGW-Standards natural gas in Germany can contain up to 5% hydrogen. The GERG, European Group on the Gas Research sees potential to increase this amount up to 6% to 20%. Power-to-gas could serve both for fuel and for the

  9. Ti-decorated graphitic-C{sub 3}N{sub 4} monolayer: A promising material for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weibin [Department of Physics, Dongguk University, Seoul 04620 (Korea, Republic of); Zhang, Zhijun [Department of Physics, Dongguk University, Seoul 04620 (Korea, Republic of); School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Zhang, Fuchun [College of Physics and Electronic Information, Yan’an University, Yan’an 716000 (China); Yang, Woochul, E-mail: wyang@dongguk.edu [Department of Physics, Dongguk University, Seoul 04620 (Korea, Republic of)

    2016-11-15

    Highlights: • Ti atoms are stably decorated at the triangular N hole in g-C{sub 3}N{sub 4} with an adsorption energy of −7.58 eV. • Electron redistribution of Ti-adsorbed porous g-C{sub 3}N{sub 4} significantly enhanced hydrogen adsorption up to five H{sub 2} molecules at each Ti atom. • The hydrogen capacity of the Ti-decorated g-C{sub 3}N{sub 4} system reaches up to 9.70 wt%. • All H{sub 2} absorbed in the Ti/g-C{sub 3}N{sub 4} system can be released at 393 K according to the molecular dynamic analysis. • Ti/g-C{sub 3}N{sub 4} as a hydrogen storage system is suitable and reversible at the temperature range required for practical applications. - Abstract: Ti-decorated graphitic carbon nitride (g-C{sub 3}N{sub 4}) monolayer as a promising material system for high-capacity hydrogen storage is proposed through density functional theory calculations. The stability and hydrogen adsorption of Ti-decorated g-C{sub 3}N{sub 4} is analyzed by computing the adsorption energy, the charge population, and electronic density of states. The most stable decoration site of Ti atom is the triangular N hole in g-C{sub 3}N{sub 4} with an adsorption energy of −7.58 eV. The large diffusion energy barrier of the adsorbed Ti atom of ∼6.00 eV prohibits the cluster formation of Ti atoms. The electric field induced by electron redistribution of Ti-adsorbed porous g-C{sub 3}N{sub 4} significantly enhanced hydrogen adsorption up to five H{sub 2} molecules at each Ti atom with an average adsorption energy of −0.30 eV/H{sub 2}. The corresponding hydrogen capacity reaches up to 9.70 wt% at 0 K. In addition, the hydrogen capacity is predicted to be 6.30 wt% at 233 K and all adsorbed H{sub 2} are released at 393 K according to molecular dynamics simulation. Thus, the Ti-decorated g-C{sub 3}N{sub 4} monolayer is suggested to be a promising material for hydrogen storage suggested by the DOE for commercial applications.

  10. Membrane reforming in converting natural gas to hydrogen (part one)

    Energy Technology Data Exchange (ETDEWEB)

    Barba, D; Giacobbe, F; De Cesaris, A [Faculty of Chemical Engineering and Materials, University of L' Aquila (Italy); Farace, A; Iaquaniello, G; Pipino, A [TECHNIP-KTI S.p.a., Rome (Italy)

    2008-07-15

    Membrane reforming reactors (MRR) could play a key role in converting natural gas into hydrogen. The major advantage of MRR architecture is the possibility to shift the chemical equilibrium toward the right-hand side of the reaction, improving hydrogen production and allowing, the same time high methane conversion at relatively low temperatures such as 650 C. Such a low operating temperature makes it possible to locate the MRR downstream of a gas turbine, achieving an efficient hybrid system (power+hydrogen) with a significant reduction in energy consumption (around 10%). This paper discusses the whole innovative architecture where conventional tubular reforming is integrated with hydrogen permeable palladium membrane separators. The fundamental concepts are analyzed and integrated into a process scheme; the structural effects of variables design such as reactor temperature outlet, S/C ratio and recycle ratio throughout pinch and sensitivity analysis are described, and a comparison of the process economics with conventional hydrogen technology is presented at the end of the second part of this paper. The production of highly reliable, defect-free and reproducible, Pd-alloy membranes for selective hydrogen separation is a key issue in the proposed hybrid architecture. (author)

  11. Tritium removal by hydrogen isotopic exchange between hydrogen gas and water on hydrophobic catalyst

    International Nuclear Information System (INIS)

    Morishita, T.; Isomura, S.; Izawa, H.; Nakane, R.

    1980-01-01

    Many kinds of the hydrophobic catalysts for hydrogen isotopic exchange between hydrogen gas and water have been prepared. The carriers are the hydrophobic organic materials such as polytetrafluoroethylene(PTFE), monofluorocarbon-PTFE mixture(PTFE-FC), and styrene-divinylbenzene copolymer(SDB). 0.1 to 2 wt % Pt is deposited on the carriers. The Pt/SDB catalyst has much higher activity than the Pt/PTFE catalyst and the Pt/PTFE-FC catalyst shows the intermediate value of catalytic activity. The observation of electron microscope shows that the degrees of dispersion of Pt particles on the hydrophobic carriers result in the difference of catalytic activities. A gas-liquid separated type column containing ten stages is constructed. Each stage is composed of both the hydrophobic catalyst bed for the hydrogen gas/water vapor isotopic exchange and the packed column type bed for the water vapor/liquid water isotopic exchange. In the column hydrogen gas and water flow countercurrently and hydrogen isotopes are separated

  12. Utilization of hydrogen gas production for electricity generation in ...

    African Journals Online (AJOL)

    Utilization of hydrogen gas production for electricity generation in fuel cell by Enterobacter aerogenes ADH 43 with many kinds of carbon sources in batch stirred tank reactor. MA Rachman, LD Eniya, Y Liasari, MM Nasef, A Ahmad, H Saidi ...

  13. Experimental study on flame propagation characteristics of Hydrogen premixed gas in gas pipeline

    Science.gov (United States)

    Ma, Danzhu; Li, Zhuang; Jia, Fengrui; Li, Zhou

    2018-06-01

    Hydrogen is the cleanest high-energy gas fuel, and also is the main industrial material. However, hydrogen is more explosive and more powerful than conventional gas fuels, which restricts its application. In particular, the expansion of premixed combustion under a strong constraint is more complicated, the reaction spreads faster. The flame propagation characteristics of premixed hydrogen/air were investigated by experiment. The mechanism of reaction acceleration is discussed, and then the speed of the flame propagation and the reaction pressure were tested and analysed.

  14. Study on disposal method of graphite blocks and storage of spent fuel for modular gas-cooled reactor. Joint research

    Energy Technology Data Exchange (ETDEWEB)

    Sumita, Junya; Sawa, Kazuhiro; Kunitomi, Kazuhiko [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Tsuchie, Yasuo; Urakami, Masao [Japan Atomic Power Co., Tokyo (Japan)

    2003-02-01

    This report describes the result of study on disposal method of graphite blocks in future block-type reactor. Present study was carried out within a framework of joint research, ''Research of Modular High Temperature Gas-cooled Reactors (No. 3)'', between Japan Atomic Energy Research Institute (JAERI) and the Japan Atomic Power Company (JAPCO), in 2000. In this study, activities in fuel and reflector graphite blocks were evaluated and were compared with the disposal limits defined as low-level of radioactive waste. As a result, it was found that the activity for only C-14 was higher than disposal limits for the low-level of radioactive waste and that the amount of air in the graphite is important to evaluate precisely of C-14 activity. In addition, spent fuels can be stored in air-cooled condition at least after two years cooling in the storage pool. (author)

  15. Production of hydrogen by thermocatalytic cracking of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Muradov, N. [Florida Solar Energy Center, Cocoa, FL (United States)

    1996-10-01

    The conventional methods of hydrogen production from natural gas (for example, steam reforming and partial oxidation) are complex, multi-step processes that produce large quantities of CO{sub 2}. The main goal of this project is to develop a technologically simple process for hydrogen production from natural gas (NG) and other hydrocarbon fuels via single-step decomposition of hydrocarbons. This approach eliminates or significantly reduces CO{sub 2} emission. Carbon is a valuable by-product of this process, whereas conventional methods of hydrogen production from NG produce no useful by-products. This approach is based on the use of special catalysts that reduce the maximum temperature of the process from 1400-1500{degrees}C (thermal non-catalytic decomposition of methane) to 500-900{degrees}C. Transition metal based catalysts and various forms of carbon are among the candidate catalysts for the process. This approach can advantageously be used for the development of compact NG reformers for on-site production of hydrogen-methane blends at refueling stations and, also, for the production of hydrogen-rich gas for fuel cell applications. The author extended the search for active methane decomposition catalysts to various modifications of Ni-, Fe-, Mo- and Co-based catalysts. Variation in the operational parameters makes it possible to produce H{sub 2}-CH{sub 4} blends with a wide range of hydrogen concentrations that vary from 15 to 98% by volume. The author found that Ni-based catalysts are more effective at temperatures below 750{degrees}C, whereas Fe-based catalysts are effective at temperatures above 800{degrees}C for the production of hydrogen with purity of 95% v. or higher. The catalytic pyrolysis of liquid hydrocarbons (pentane, gasoline) over Fe-based catalyst was conducted. The author observed the production of a hydrogen-rich gas (hydrogen concentration up to 97% by volume) at a rate of approximately 1L/min.mL of hydrocarbon fuel.

  16. Effect of active zinc oxide dispersion on reduced graphite oxide for hydrogen sulfide adsorption at mid-temperature

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hoon Sub [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L3G1 (Canada); Greenhouse Gas Department, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon, 305-343 (Korea, Republic of); Park, Moon Gyu [Department of Chemical Engineering Education, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 305-764 (Korea, Republic of); Croiset, Eric, E-mail: ecroiset@uwaterloo.ca [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L3G1 (Canada); Chen, Zhongwei [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L3G1 (Canada); Nam, Sung Chan; Ryu, Ho-Jung [Greenhouse Gas Department, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon, 305-343 (Korea, Republic of); Yi, Kwang Bok, E-mail: cosy32@cnu.ac.kr [Department of Chemical Engineering Education, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 305-764 (Korea, Republic of)

    2013-09-01

    Composites of Zinc oxide (ZnO) with reduced graphite oxide (rGO) were synthesized and used as adsorbents for hydrogen sulfide (H{sub 2}S) at 300 °C. Various characterization methods (TGA, XRD, FT-IR, TEM and XPS) were performed in order to link their H{sub 2}S adsorption performance to the properties of the adsorbent's surface. Microwave-assisted reduction process of graphite oxide (GO) provided mild reduction environment, allowing oxygen-containing functional groups to remain on the rGO surface. It was confirmed that for the ZnO/rGO synthesize using the microwave-assisted reduction method, the ZnO particle size and the degree of ZnO dispersion remained stable over time at 300 °C, which was not the case for only the ZnO particles themselves. This stable highly dispersed feature allows for sustained high surface area over time. This was confirmed through breakthrough experiments for H{sub 2}S adsorption where it was found that the ZnO/rGO composite showed almost four times higher ZnO utilization efficiency than ZnO itself. The effect of the H{sub 2} and CO{sub 2} on H{sub 2}S adsorption was also investigated. The presence of hydrogen in the H{sub 2}S stream had a positive effect on the removal of H{sub 2}S since it allows a reducing environment for Zn-O and Zn-S bonds, leading to more active sites (Zn{sup 2+}) to sulfur molecules. On the other hand, the presence of carbon dioxide (CO{sub 2}) showed the opposite trend, likely due to the oxidation environment and also due to possible competitive adsorption between H{sub 2}S and CO{sub 2}.

  17. Effect of active zinc oxide dispersion on reduced graphite oxide for hydrogen sulfide adsorption at mid-temperature

    Science.gov (United States)

    Song, Hoon Sub; Park, Moon Gyu; Croiset, Eric; Chen, Zhongwei; Nam, Sung Chan; Ryu, Ho-Jung; Yi, Kwang Bok

    2013-09-01

    Composites of Zinc oxide (ZnO) with reduced graphite oxide (rGO) were synthesized and used as adsorbents for hydrogen sulfide (H2S) at 300 °C. Various characterization methods (TGA, XRD, FT-IR, TEM and XPS) were performed in order to link their H2S adsorption performance to the properties of the adsorbent's surface. Microwave-assisted reduction process of graphite oxide (GO) provided mild reduction environment, allowing oxygen-containing functional groups to remain on the rGO surface. It was confirmed that for the ZnO/rGO synthesize using the microwave-assisted reduction method, the ZnO particle size and the degree of ZnO dispersion remained stable over time at 300 °C, which was not the case for only the ZnO particles themselves. This stable highly dispersed feature allows for sustained high surface area over time. This was confirmed through breakthrough experiments for H2S adsorption where it was found that the ZnO/rGO composite showed almost four times higher ZnO utilization efficiency than ZnO itself. The effect of the H2 and CO2 on H2S adsorption was also investigated. The presence of hydrogen in the H2S stream had a positive effect on the removal of H2S since it allows a reducing environment for Znsbnd O and Znsbnd S bonds, leading to more active sites (Zn2+) to sulfur molecules. On the other hand, the presence of carbon dioxide (CO2) showed the opposite trend, likely due to the oxidation environment and also due to possible competitive adsorption between H2S and CO2.

  18. Effect of active zinc oxide dispersion on reduced graphite oxide for hydrogen sulfide adsorption at mid-temperature

    International Nuclear Information System (INIS)

    Song, Hoon Sub; Park, Moon Gyu; Croiset, Eric; Chen, Zhongwei; Nam, Sung Chan; Ryu, Ho-Jung; Yi, Kwang Bok

    2013-01-01

    Composites of Zinc oxide (ZnO) with reduced graphite oxide (rGO) were synthesized and used as adsorbents for hydrogen sulfide (H 2 S) at 300 °C. Various characterization methods (TGA, XRD, FT-IR, TEM and XPS) were performed in order to link their H 2 S adsorption performance to the properties of the adsorbent's surface. Microwave-assisted reduction process of graphite oxide (GO) provided mild reduction environment, allowing oxygen-containing functional groups to remain on the rGO surface. It was confirmed that for the ZnO/rGO synthesize using the microwave-assisted reduction method, the ZnO particle size and the degree of ZnO dispersion remained stable over time at 300 °C, which was not the case for only the ZnO particles themselves. This stable highly dispersed feature allows for sustained high surface area over time. This was confirmed through breakthrough experiments for H 2 S adsorption where it was found that the ZnO/rGO composite showed almost four times higher ZnO utilization efficiency than ZnO itself. The effect of the H 2 and CO 2 on H 2 S adsorption was also investigated. The presence of hydrogen in the H 2 S stream had a positive effect on the removal of H 2 S since it allows a reducing environment for Zn-O and Zn-S bonds, leading to more active sites (Zn 2+ ) to sulfur molecules. On the other hand, the presence of carbon dioxide (CO 2 ) showed the opposite trend, likely due to the oxidation environment and also due to possible competitive adsorption between H 2 S and CO 2 .

  19. Impact of radiolysis and radiolytic corrosion on the release of {sup 13}C and {sup 37}Cl implanted into nuclear graphite: Consequences for the behaviour of {sup 14}C and {sup 36}Cl in gas cooled graphite moderated reactors

    Energy Technology Data Exchange (ETDEWEB)

    Moncoffre, N., E-mail: nathalie.moncoffre@ipnl.in2p3.fr [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Toulhoat, N. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); CEA/DEN, Centre de Saclay (France); Bérerd, N.; Pipon, Y. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Université de Lyon, Université Lyon, IUT Lyon-1 département chimie (France); Silbermann, G. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); EDF – DPI - DIN – CIDEN, DIE - Division Environnement, Lyon (France); Blondel, A. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Andra, Châtenay-Malabry (France); Galy, N. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); EDF – DPI - DIN – CIDEN, DIE - Division Environnement, Lyon (France); and others

    2016-04-15

    Graphite finds widespread use in many areas of nuclear technology based on its excellent moderator and reflector qualities as well as its strength and high temperature stability. Thus, it has been used as moderator or reflector in CO{sub 2} cooled nuclear reactors such as UNGG, MAGNOX, and AGR. However, neutron irradiation of graphite results in the production of {sup 14}C (dose determining radionuclide) and {sup 36}Cl (long lived radionuclide), these radionuclides being a key issue regarding the management of the irradiated waste. Whatever the management option (purification, storage, and geological disposal), a previous assessment of the radioactive inventory and the radionuclide's location and speciation has to be made. During reactor operation, the effects of radiolysis are likely to promote the radionuclide release especially at the gas/graphite interface. Radiolysis of the coolant is mainly initiated through γ irradiation as well as through Compton electrons in the graphite pores. Radiolysis can be simulated in laboratory using γ irradiation or ion irradiation. In this paper, {sup 13}C, {sup 37}Cl and {sup 14}N are implanted into virgin nuclear graphite in order to simulate respectively the presence of {sup 14}C, {sup 36}Cl and nitrogen, a {sup 14}C precursor. Different irradiation experiments were carried out using different irradiation devices on implanted graphite brought into contact with a gas simulating the coolant. The aim was to assess the effects of gas radiolysis and radiolytic corrosion induced by γ or He{sup 2+} irradiation at the gas/graphite interface in order to evaluate their role on the radionuclide release. Our results allow inferring that radiolytic corrosion has clearly promoted the release of {sup 14}C, {sup 36}Cl and {sup 14}N located at the graphite brick/gas interfaces and open pores.

  20. Production of hydrogen gas from novel chemical hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Aiello, R.; Matthews, M.A. [South Carolina Univ., Chemical Engineering Dept., Columbia, SC (United States); Reger, D.L.; Collins, J.E. [South Carolina Univ., Chemistry and Biochemistry Dept., Columbia, SC (United States)

    1998-12-01

    Six ligand-stabilized complexes have been synthesized and tested for use as hydrogen storage media for portable fuel cell applications. The new hydrides are: [HC(3,5-Me{sub 2}pz){sub 3}]LiBH{sub 4} (1), [[H{sub 2}C(3,5-Me{sub 2}pz){sub 2}]LiBH{sub 4})]{sub 2} (2) (pz = pyrazolyl), [(TMEDA)Li(BH{sub 4})]{sub 2} (3) (TMEDA (CH{sub 3}){sub 2}NCH{sub 2}CH{sub 2}N(CH{sub 3}){sub 2}), [HC(pz){sub 3}]LiBH{sub 4} (4), [[H{sub 2}C(pz){sub 2}]Li(BH{sub 4})]{sub 2} (5) and Mg(BH{sub 4}){sub 2}3THF (6) (THF = tetrahydrofuran). Hydrolysis reactions of the compounds liberate hydrogen in quantities which range from 56 to 104 ({+-}5%) of the theoretical yield. Gas chromatographic analysis of the product gases from these reactions indicate that hydrogen is the only gas produced. Thermally initiated reactions of the novel compounds with NH{sub 4}Cl were unsuccessful. Although the amount of hydrogen energy which can be theoretically obtained per unit weight is lower than that of the classical hydrides such as LiBH{sub 4} and NaBH{sub 4}, the reactions are less violent and hydrolysis of compounds 1, 2, 4, 5 and 6 releases less heat per mole of hydrogen generated. (Author)

  1. Gas--liquid equilibria in mixtures of hydrogen and thianaphthene

    Energy Technology Data Exchange (ETDEWEB)

    Sebastian, H M; Simnick, J J; Lin, H M; Chao, K C

    1978-12-01

    Gas--liquid equilibrium conditions in binary mixtures of hydrogen and thianaphthene were experimentally determined at temperature of 190 to 430/sup 0/C and pressures to 250 atm in a flow apparatus. The same apparatus was also employed to measure the vapor pressure of thianaphthene. Comparisons of the new mixture data with Chao--Seader and Grayson--Streed correlations show that both correlations predict the thianaphthene equilibrium ratios well but are in error by up to about 45 and 35% respectively for K-values of hydrogen. 4 figures, 2 tables.

  2. Tritiated hydrogen gas storage systems for a fusion plant

    International Nuclear Information System (INIS)

    Bramy, W.; Hircq, B.; Peyrat, M.; Leger, D.

    1992-01-01

    This paper reports that USSI INGENIERIE has carried out a study financed by European Communities Commission concerning the NET/ITER project, on tritium Fuel Management and Storage systems of the International Thermonuclear Experimental Reactor. A processing block diagram for hydrogen isotopes represents all interfaces and possible links between these systems and tritiated gas mixtures flowing through the Fusion plant. Large quantities of hydrogen isotopes (up to several thousand moles of protium, deuterium and tritium) in gaseous form associated with torus fuelling and exhaust pellet injection, and neutral beam injection, must be stored and managed in such a plant

  3. Hydrogen and Hydrogen/Natural Gas Station and Vehicle Operations - 2006 Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Francfort; Donald Karner; Roberta Brayer

    2006-09-01

    This report is a summary of the operations and testing of internal combustion engine vehicles that were fueled with 100% hydrogen and various blends of hydrogen and compressed natural gas (HCNG). It summarizes the operations of the Arizona Public Service Alternative Fuel Pilot Plant, which produces, compresses, and dispenses hydrogen fuel. Other testing activities, such as the destructive testing of a CNG storage cylinder that was used for HCNG storage, are also discussed. This report highlights some of the latest technology developments in the use of 100% hydrogen fuels in internal combustion engine vehicles. Reports are referenced and WWW locations noted as a guide for the reader that desires more detailed information. These activities are conducted by Arizona Public Service, Electric Transportation Applications, the Idaho National Laboratory, and the U.S. Department of Energy’s Advanced Vehicle Testing Activity.

  4. Hydrogen trapping in and release from tungsten: modeling and comparison with graphite with regard to its use as fusion reactor material

    International Nuclear Information System (INIS)

    Franzen, P.; Garcia-Rosales, C.; Plank, H.; Alimov, V.Kh.

    1997-01-01

    Trapping and release of deuterium implanted in tungsten is investigated by modeling the results of reemission, thermal and isothermal desorption experiments. Rate coefficients and activation energies for diffusion, trapping and detrapping are derived. Hydrogen atoms are able to diffuse deep into tungsten, establishing a solute amount of the same order of magnitude as the trapped one. This 'diffusion zone' exceeds the implantation zone by more than two orders of magnitude, even at room temperature. The solute amount of hydrogen in tungsten depends only slightly on the incident ion energy, but scales with implantation fluence. This high amount of solute hydrogen is the main difference of tungsten compared to graphite where nearly all hydrogen is trapped in the implantation zone, the solute amount being orders of magnitude lower. The resulting unlimited accumulation of hydrogen in tungsten deep in the material down to the backward surface disadvantages tungsten as fusion reactor material with regard to hydrogen recycling properties. (orig.)

  5. An investigation of heat exchanger fouling in dust suspension cooling systems using graphite powder and carbon dioxide gas

    International Nuclear Information System (INIS)

    Garton, D.A.; Hawes, R.I.; Rose, P.W.

    1966-01-01

    Some experiments have been performed to study the fouling of heat exchanger surfaces where heat is being transferred from a heated fluid to a cooled surface. The fluid studied was a suspension of 4-5 microns mean diameter graphite powder in carbon dioxide gas at near atmospheric pressures. The solids loading range covered was from 5 to 30 lb. graphite/lb. carbon dioxide, and gas Reynolds numbers from 6000 to 16000. Temperature gradients across the cooler of from 20 to 120 deg. C were obtained. The heat transfer ratio is correlated to show the dependence upon the solids loading ratio of the suspension, the gas Reynolds number and the temperature gradient across the cooler. The results have demonstrated that stringent precautions are necessary to ensure complete dryness of the graphite powder and the loop flow surfaces before any quantitative fouling data can be obtained, as the presence of entrained moisture will accelerate the deposition of material on the cold walls of the heat exchanger and can result in plugging. The heat transfer coefficient showed no obvious dependency upon either the gas Reynolds number or the temperature gradient across the cooler over the range investigated. The measured heat transfer coefficient was considerably lower than that obtained when the heat is transferred from a hot wall to a cooler fluid. At a solids loading of 30 lb, graphite/lb. carbon dioxide, the heat transfer coefficient was only 50% of that for heat transfer from a heated wall. At solids loadings below 7 lb/lb., the heat transfer was less than that for a gas alone. (author)

  6. Treatment and Disposal of the Radioactive Graphite Waste of High-Temperature Gas-Cooled Reactor Spent Fuel

    International Nuclear Information System (INIS)

    Li Junfeng

    2016-01-01

    High-temperature gas-cooled reactors (HTGRs) represent one of the Gen IV reactors in the future market, with efficient generation of energy and the supply of process heat at high temperature utilised in many industrial processes. HTGR development has been carried out within China’s National High Technology Research and Development Program. The first industrial demonstration HTGR of 200 MWe is under construction in Shandong Province China. HTGRs use ceramic-coated fuel particles that are strong and highly resistant to irradiation. Graphite is used as moderator and helium is used as coolant. The fuel particles and the graphite block in which they are imbedded can withstand very high temperature (up to ~1600℃). Graphite waste presents as the fuel element components of HTGR with up to 95% of the whole element beside the graphite blocks in the core. For example, a 200 MWe reactor could discharge about 90,000 fuel elements with 17 tonnes irradiated graphite included each year. The core of the HTGR in China consists of a pebble bed with spherical fuel elements. The UO 2 fuel kernel particles (0.5mm diameter) (triple-coated isotropic fuel particles) are coated by several layers including inner buffer layer with less dense pyrocarbon, dense pyro-carbon, SiC layer and outer layer of dense pyro-carbon, which can prevent the leaking of fission products (Fig. 1). Spherical fuel elements (60mm diameter) consist of a 50mm diameter inner zone and 5mm thick shell of fuel free zone [3]. The inner zone contains about 8300 triple-coated isotropic fuel particles of 0.92mm in diameter dispersed in the graphite matrix

  7. Brazing graphite to graphite

    International Nuclear Information System (INIS)

    Peterson, G.R.

    1976-01-01

    Graphite is joined to graphite by employing both fine molybdenum powder as the brazing material and an annealing step that together produce a virtually metal-free joint exhibiting properties similar to those found in the parent graphite. Molybdenum powder is placed between the faying surfaces of two graphite parts and melted to form molybdenum carbide. The joint area is thereafter subjected to an annealing operation which diffuses the carbide away from the joint and into the graphite parts. Graphite dissolved by the dispersed molybdenum carbide precipitates into the joint area, replacing the molybdenum carbide to provide a joint of graphite

  8. Laser-driven nuclear-polarized hydrogen internal gas target

    International Nuclear Information System (INIS)

    Seely, J.; Crawford, C.; Clasie, B.; Xu, W.; Dutta, D.; Gao, H.

    2006-01-01

    We report the performance of a laser-driven polarized internal hydrogen gas target (LDT) in a configuration similar to that used in scattering experiments. This target used the technique of spin-exchange optical pumping to produce nuclear spin polarized hydrogen gas that was fed into a cylindrical storage (target) cell. We present in this paper the performance of the target, methods that were tried to improve the figure-of-merit (FOM) of the target, and a Monte Carlo simulation of spin-exchange optical pumping. The dimensions of the apparatus were optimized using the simulation and the experimental results were in good agreement with the results from the simulation. The best experimental result achieved was at a hydrogen flow rate of 1.1x10 18 atoms/s, where the sample beam exiting the storage cell had 58.2% degree of dissociation and 50.5% polarization. Based on this measurement, the atomic fraction in the storage cell was 49.6% and the density averaged nuclear polarization was 25.0%. This represents the highest FOM for hydrogen from an LDT and is higher than the best FOM reported by atomic beam sources that used storage cells

  9. Triboelectric Hydrogen Gas Sensor with Pd Functionalized Surface

    Directory of Open Access Journals (Sweden)

    Sung-Ho Shin

    2016-10-01

    Full Text Available Palladium (Pd-based hydrogen (H2 gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H2 gas sensors; however, all the sensors must be powered through an external battery. We report here an H2 gas sensor that can detect H2 by measuring the output voltages generated during contact electrification between two friction surfaces. When the H2 sensor, composed of Pd-coated ITO (indium tin oxide and PET (polyethylene Terephthalate film, is exposed to H2, its output voltage is varied in proportion to H2 concentration because the work function (WF of Pd-coated surface changes, altering triboelectric charging behavior. Specifically, the output voltage of the sensor is gradually increased as exposing H2 concentration increases. Reproducible and sensitive sensor response was observed up 1% H2 exposure. The approach introduced here can easily be adopted to development of triboelectric gas sensors detecting other gas species.

  10. Warm Pressurant Gas Effects on the Liquid Hydrogen Bubble Point

    Science.gov (United States)

    Hartwig, Jason W.; McQuillen, John B.; Chato, David J.

    2013-01-01

    This paper presents experimental results for the liquid hydrogen bubble point tests using warm pressurant gases conducted at the Cryogenic Components Cell 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device. Three fine mesh screen samples (325 x 2300, 450 x 2750, 510 x 3600) were tested in liquid hydrogen using cold and warm noncondensible (gaseous helium) and condensable (gaseous hydrogen) pressurization schemes. Gases were conditioned from 0 to 90 K above the liquid temperature. Results clearly indicate a degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over noncondensible pressurization. Degradation in the bubble point pressure is inversely proportional to screen porosity, as the coarsest mesh demonstrated the highest degradation. Results here have implication on both pressurization and LAD system design for all future cryogenic propulsion systems. A detailed review of historical heated gas tests is also presented for comparison to current results.

  11. EUV tools: hydrogen gas purification and recovery strategies

    Science.gov (United States)

    Landoni, Cristian; Succi, Marco; Applegarth, Chuck; Riddle Vogt, Sarah

    2015-03-01

    The technological challenges that have been overcome to make extreme ultraviolet lithography (EUV) a reality have been enormous1. This vacuum driven technology poses significant purity challenges for the gases employed for purging and cleaning the scanner EUV chamber and source. Hydrogen, nitrogen, argon and ultra-high purity compressed dry air (UHPCDA) are the most common gases utilized at the scanner and source level. Purity requirements are tighter than for previous technology node tools. In addition, specifically for hydrogen, EUV tool users are facing not only gas purity challenges but also the need for safe disposal of the hydrogen at the tool outlet. Recovery, reuse or recycling strategies could mitigate the disposal process and reduce the overall tool cost of operation. This paper will review the types of purification technologies that are currently available to generate high purity hydrogen suitable for EUV applications. Advantages and disadvantages of each purification technology will be presented. Guidelines on how to select the most appropriate technology for each application and experimental conditions will be presented. A discussion of the most common approaches utilized at the facility level to operate EUV tools along with possible hydrogen recovery strategies will also be reported.

  12. Process for hydrogen isotope exchange and concentration between liquid water and hydrogen gas and catalyst assembly therefor

    International Nuclear Information System (INIS)

    Stevens, W.H.

    1975-01-01

    A bithermal, catalytic, hydrogen isotope exchange process between liquid water and hydrogen gas to effect concentration of the deuterium isotope of hydrogen is described. Liquid water and hydrogen gas are contacted with one another and with at least one catalytically active metal selected from Group VIII of the Periodic Table; the catalyst body has a water repellent, gas and water vapor permeable, organic polymer or resin coating, preferably a fluorinated olefin polymer or silicone resin coating, so that the isotope exchange takes place by two simultaneously occurring, and closely coupled in space, steps and concentration is effected by operating two interconnected sections containing catalyst at different temperatures. (U.S.)

  13. Experimental Study of Gas Explosions in Hydrogen Sulfide-Natural Gas-Air Mixtures

    Directory of Open Access Journals (Sweden)

    André Vagner Gaathaug

    2014-01-01

    Full Text Available An experimental study of turbulent combustion of hydrogen sulfide (H2S and natural gas was performed to provide reference data for verification of CFD codes and direct comparison. Hydrogen sulfide is present in most crude oil sources, and the explosion behaviour of pure H2S and mixtures with natural gas is important to address. The explosion behaviour was studied in a four-meter-long square pipe. The first two meters of the pipe had obstacles while the rest was smooth. Pressure transducers were used to measure the combustion in the pipe. The pure H2S gave slightly lower explosion pressure than pure natural gas for lean-to-stoichiometric mixtures. The rich H2S gave higher pressure than natural gas. Mixtures of H2S and natural gas were also studied and pressure spikes were observed when 5% and 10% H2S were added to natural gas and also when 5% and 10% natural gas were added to H2S. The addition of 5% H2S to natural gas resulted in higher pressure than pure H2S and pure natural gas. The 5% mixture gave much faster combustion than pure natural gas under fuel rich conditions.

  14. Potential application of gas chromatography to the analysis of hydrogen isotopes

    International Nuclear Information System (INIS)

    Warner, D.K.; Sprague, R.E.; Bohl, D.R.

    1976-01-01

    Gas chromatography is used at Mound Laboratory for the analysis of hydrogen isotopic impurities in gas mixtures. This instrumentation was used to study the applicability of the gas chromatography technique to the determination of the major components of hydrogen isotopic gas mixtures. The results of this study, including chromatograms and precision data, are presented

  15. Numerical analysis of mass transfer with graphite oxidation in a laminar flow of multi-component gas mixture through a circular tube

    International Nuclear Information System (INIS)

    Ogawa, Masuro

    1992-10-01

    In the present paper, mass transfer has been numerically studied in a laminar flow through a circular graphite tube to evaluate graphite corrosion rate and generation rate of carbon monoxide during a pipe rupture accident in a high temperature gas cooled reactor. In the analysis, heterogeneous (graphite oxidation and graphite/carbon dioxide reaction) and homogeneous (carbon monoxide combustion) chemical reactions were dealt in the multi-component gas mixture; helium, oxygen, carbon monoxide and carbon dioxide. Multi-component diffusion coefficients were used in a diffusion term. Mass conservation equations of each gas component, mass conservation equation and momentum conservation equations of the gas mixture were solved by using SIMPLE algorism. Chemical reactions between graphite and oxygen, graphite and carbon dioxide, and carbon monoxide combustion were taken into account in the present numerical analysis. An energy equation for the gas mixture was not solved and temperature was held to be constant in order to understand basic mass transfer characteristics without heat transfer. But, an energy conservation equation for single component gas was added to know heat transfer characteristics without mass transfer. The effects of these chemical reactions on the mass transfer coefficients were quantitatively and qualitatively clarified in the range of 50 to 1000 of inlet Reynolds numbers, 0 to 0.5 of inlet oxygen mass fraction and 800 to 1600degC of temperature. (author)

  16. Hydrogen gettering the overpressure gas from highly radioactive liquids

    International Nuclear Information System (INIS)

    Riley, D.L.; Schicker, J.R.

    1996-04-01

    Remediation of current inventories of high-activity radioactive liquid waste (HALW) requires transportation of Type-B quantities of radioactive material, possibly up to several hundred liters. However, the only currently certified packaging is limited to quantities of 50 ml (0.01 gal) quantities of Type-B radioactive liquid. Efforts are under way to recertify the existing packaging to allow the shipment of up to 4 L (1.1 gal) of Type-B quantities of HALW, but significantly larger packaging could be needed in the future. Scoping studies and preliminary designs have identified the feasibility of retrofitting an insert into existing casks, allowing the transport of up to 380 L (100 gal) of HALW. However, the insert design and ultimate certification strategy depend heavily on the gas-generating attributes of the HALW. A non-vented containment vessel filled with HALW, in the absence of any gas-mitigation technologies, poses a deflagration threat and, therefore, gas generation, specifically hydrogen generation, must be reliably controlled during all phases of transportation. Two techniques are available to mitigate hydrogen accumulation: recombiners and getters. Getters have an advantage over recombiners in that oxides are not required to react with the hydrogen. A test plan was developed to evaluate three forms of getter material in the presence of both simulated HALW and the gases that are produced by the HALW. These tests demonstrated that getters can react with hydrogen in the presence of simulated waste and in the presence of several other gases generated by the HALW, such as nitrogen, ammonia, nitrous oxide, and carbon monoxide. Although the use of such a gettering system has been shown to be technically feasible, only a preliminary design for its use has been completed. No further development is planned until the requirement for bulk transport of Type-B quantities of HALW is more thoroughly defined

  17. Efficiency of hydrogen gas production in a stand-alone solar hydrogen system

    International Nuclear Information System (INIS)

    Singh, K.; Tamakloe, R.Y.

    2003-01-01

    Many photovoltaic systems operate in a decentralised electricity producing system, or stand-alone mode and the total energy demand is met by the output of the photovoltaic array. The output of the photovoltaic system fluctuates and is unpredictable for many applications making some forms of energy storage system necessary. The role of storage medium is to store the excess energy produced by the photovoltaic arry, to absorb momentary power peaks and to supply energy during sunless periods. One of the storage modes is the use of electrochemical techniques, with batteries and water electrolysis as the most important examples. The present study includes three main parts: the first one is the hydrogen production form the electrolysis of water depending on the DC output current of the photovoltaic (PV) energy source and the charging of the battery. The second part presents the influence of various parameters on the efficiency of hydrogen gas production. The final part includes simulation studies with focus on solar hydrogen efficiency under the influence of various physical and chemical parameters. For a 50W panel-battery-electrolyser system, the dependence of volume of hydrogen gas on voltage, current and power yielded a maximum efficiency of 13.6% (author)

  18. ELECTROCHEMICAL SEPARATION AND CONCENTRATION OF HYDROGEN SULFIDE FROM GAS MIXTURES

    Science.gov (United States)

    Winnick, Jack; Sather, Norman F.; Huang, Hann S.

    1984-10-30

    A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

  19. Injection of a relativistic electron beam into neutral hydrogen gas

    International Nuclear Information System (INIS)

    de Haan, P.H.; Janssen, G.C.A.M.; Hopman, H.J.; Granneman, E.H.A.

    1982-01-01

    The injection of a relativistic electron beam (0.8 MeV, 6 kA, 150 nsec) into hydrogen gas of 190 Pa pressure results in a plasma with density n/sub e/approx. =10 20 m -3 and temperature kT/sub e/< or approx. =kT/sub i/approx. =3.5 eV. The results of the measurements show good agreement with computations based on a model combining gas ionization and turbulent plasma heating. It is found that a quasistationary state exists in which the energy lost by the beam (about 6% of the total kinetic energy of the beam) is partly used to further ionize and dissociate the gas and for the other part is lost as line radiation

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

    International Nuclear Information System (INIS)

    Maria Flytzani-Stephanopoulos; Jerry Meldon; Xiaomei Qi

    2001-01-01

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

  1. The problem of gas gap between graphite - fuel channel reduction impact at Ignalina NPP

    International Nuclear Information System (INIS)

    1999-01-01

    Safety analysis of Ignalina NPP operation in the case when gap closure between graphite - fuel channel occur was performed. The main results of this analysis as well as data of gap measurements during the year 1996 - 1998 are provided

  2. Measurement of laminar burning velocities and Markstein lengths of diluted hydrogen-enriched natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Haiyan; Jiao, Qi; Huang, Zuohua; Jiang, Deming [State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Eng., Xi' an Jiaotong University (China)

    2009-01-15

    The laminar flame characteristics of natural gas-hydrogen-air-diluent gas (nitrogen/CO{sub 2}) mixtures were studied in a constant volume combustion bomb at various diluent ratios, hydrogen fractions and equivalence ratios. Both unstretched laminar burning velocity and Markstein length were obtained. The results showed that hydrogen fraction, diluent ratio and equivalence ratio have combined influence on laminar burning velocity and flame instability. The unstretched laminar burning velocity is reduced at a rate that is increased with the increase of the diluent ratio. The reduction effect of CO{sub 2} diluent gas is stronger than that of nitrogen diluent gas. Hydrogen-enriched natural gas with high hydrogen fraction can tolerate more diluent gas than that with low hydrogen fraction. Markstein length can either increase or decrease with the increase of the diluent ratio, depending on the hydrogen fraction of the fuel. (author)

  3. Tables of formulae for calculating the mechanics of stacks in gas-graphite reactors

    International Nuclear Information System (INIS)

    1968-01-01

    This collection of formulae only gives, for nuclear graphite stacks. The mechanical effects due to the strains, thermal or not, of steel structures supporting or surrounding graphite blocks. Equations have been established by mean of experiments made at Chinon with large pile models. Thus, it is possible to calculate displacement, strain and stress in the EDF type stacks of horizontal triangular block lattice. (authors) [fr

  4. DNA base dimers are stabilized by hydrogen-bonding interactions including non-Watson-Crick pairing near graphite surfaces.

    Science.gov (United States)

    Shankar, Akshaya; Jagota, Anand; Mittal, Jeetain

    2012-10-11

    Single- and double-stranded DNA are increasingly being paired with surfaces and nanoparticles for numerous applications, such as sensing, imaging, and drug delivery. Unlike the majority of DNA structures in bulk that are stabilized by canonical Watson-Crick pairing between Ade-Thy and Gua-Cyt, those adsorbed on surfaces are often stabilized by noncanonical base pairing, quartet formation, and base-surface stacking. Not much is known about these kinds of interactions. To build an understanding of the role of non-Watson-Crick pairing on DNA behavior near surfaces, one requires basic information on DNA base pair stacking and hydrogen-bonding interactions. All-atom molecular simulations of DNA bases in two cases--in bulk water and strongly adsorbed on a graphite surface--are conducted to study the relative strengths of stacking and hydrogen bond interactions for each of the 10 possible combinations of base pairs. The key information obtained from these simulations is the free energy as a function of distance between two bases in a pair. We find that stacking interactions exert the dominant influence on the stability of DNA base pairs in bulk water as expected. The strength of stability for these stacking interactions is found to decrease in the order Gua-Gua > Ade-Gua > Ade-Ade > Gua-Thy > Gua-Cyt > Ade-Thy > Ade-Cyt > Thy-Thy > Cyt-Thy > Cyt-Cyt. On the other hand, mutual interactions of surface-adsorbed base pairs are stabilized mostly by hydrogen-bonding interactions in the order Gua-Cyt > Ade-Gua > Ade-Thy > Ade-Ade > Cyt-Thy > Gua-Gua > Cyt-Cyt > Ade-Cyt > Thy-Thy > Gua-Thy. Interestingly, several non-Watson-Crick base pairings, which are commonly ignored, have similar stabilization free energies due to interbase hydrogen bonding as Watson-Crick pairs. This clearly highlights the importance of non-Watson-Crick base pairing in the development of secondary structures of oligonucleotides near surfaces.

  5. Study on efficient methods for removal and treatment of graphite blocks in a gas cooled reactor

    International Nuclear Information System (INIS)

    Fujii, S.; Shirakawa, M.; Murakami, T.

    2001-01-01

    Tokai Power Station (GCR, 166 MWe) started its commercial operation on July 1966 and ceased activities at the end of March 1998 after 32 years of operation. The decommissioning plans are being developed, to prepare for near future dismantling. In the study, the methods for removal of the graphite blocks of about 1,600 ton have been developed to carrying it out safely and in a short period of time, and the methods of treatment of graphite have also been developed. All technological items have been identified for which R and D work will be required for removal from the core and treatment for disposal. (1) In order to reduce the programme required for the dismantling of reactor internals, an efficient method for removal of the graphite blocks is necessary. For this purpose the design of a dismantling machine has been investigated which can extract several blocks at a time. The conceptual design has being developed and the model has been manufactured and tested in a mock-up facility. (2) In order to reduce disposal costs, it will be necessary to segment the graphite blocks, maximising the packing density available in the disposal containers. Some of the graphite blocks will be cut into pieces longitudinally by a remote machine. Relevant technical matters have been identified, such as graphite cutting methods, the nature of fine particles arising from the cutting operation, the treatment of fine particles for disposal, and the method of mortar filling inside the waste container. (author)

  6. Internal combustion engines fueled by natural gas-hydrogen mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Akansu, S.O.; Kahraman, N. [Erciyes University, Kayseri (Turkey). Engineering Faculty; Dulger, Z. [Kocaeli University (Turkey). Engineering Faculty; Veziroglu, T.N. [University of Miami, Coral Gables, FL (United States). College of Engineering

    2004-11-01

    In this study, a survey of research papers on utilization of natural gas-hydrogen mixtures in internal combustion engines is carried out. In general, HC, CO{sub 2}, and CO emissions decrease with increasing H{sub 2}, but NO{sub x} emissions generally increase. If a catalytic converter is used, NO{sub x} emission values can be decreased to extremely low levels. Consequently, equivalence zero emission vehicles (EZEV) standards may be reached. Efficiency values vary with H{sub 2} amount, spark timing, compression ratio, equivalence ratio, etc. Under certain conditions, efficiency values can be increased. In terms of BSFC, emissions and BTE, a mixture of low hydrogen percentage is suitable for using. (author)

  7. Development status on hydrogen production technology using high-temperature gas-cooled reactor at JAEA, Japan

    International Nuclear Information System (INIS)

    Shiozawa, Shusaku; Ogawa, Masuro; Hino, Ryutaro

    2006-01-01

    The high-temperature gas-cooled reactor (HTGR), which is graphite-moderated and helium-cooled, is attractive due to its unique capability of producing high temperature helium gas and its fully inherent reactor safety. In particular, hydrogen production using the nuclear heat from HTGR (up to 900 deg. C) offers one of the most promising technological solutions to curb the rising level of CO 2 emission and resulting risk of climate change. The interests in HTGR as an advanced nuclear power source for the next generation reactor, therefore, continue to rise. This is represented by the Japanese HTTR (High-Temperature Engineering Test Reactor) Project and the Chinese HTR-10 Project, followed by the international Generation IV development program, US nuclear hydrogen initiative program, EU innovative HTR technology development program, etc. To enhance nuclear energy application to heat process industries, the Japan Atomic Energy Agency (JAEA) has continued extensive efforts for development of hydrogen production system using the nuclear heat from HTGR in the framework of the HTTR Project. The HTTR Project has the objectives of establishing both HTGR technology and heat utilization technology. Using the HTTR constructed at the Oarai Research and Development Center of JAEA, reactor performance and safety demonstration tests have been conducted as planned. The reactor outlet temperature of 950 deg. C was successfully achieved in April 2004. For hydrogen production as heat utilization technology, R and D on thermo-chemical water splitting by the 'Iodine-Sulfur process' (IS process) has been conducted step by step. Proof of the basic IS process was made in 1997 on a lab-scale of hydrogen production of 1 L/h. In 2004, one-week continuous operation of the IS process was successfully demonstrated using a bench-scale apparatus with hydrogen production rate of 31 L/h. Further test using a pilot scale facility with greater hydrogen production rate of 10 - 30 m 3 /h is planned as

  8. Investigation of hydrogen evolution activity for the nickel, nickel-molybdenum nickel-graphite composite and nickel-reduced graphene oxide composite coatings

    International Nuclear Information System (INIS)

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang

    2016-01-01

    Graphical abstract: - Highlights: • Improved HER efficiency of Ni-Mo coatings was attributed to ‘cauliflower’ like microstructure. • RGO in nickel-RGO composite coating promoted refined grain and facilitated HER. • Synergistic effect between nickel and RGO facilitated HER due to large specific surface of RGO. - Abstract: The nickel, nickel-molybdenum alloy, nickel-graphite and nickel-reduced graphene oxide composite coatings were obtained by the electrodeposition technique from a nickel sulfate bath. Nanocrystalline molybdenum, graphite and reduced graphene oxide in nickel coatings promoted hydrogen evolution reaction in 0.5 M H_2SO_4 solution at room temperature. However, the nickel-reduced graphene oxide composite coating exhibited the highest electrocatalytic activity for the hydrogen evolution reaction in 0.5 M H_2SO_4 solution at room temperature. A large number of gaps between ‘cauliflower’ like grains could decrease effective area for hydrogen evolution reaction in slight amorphous nickel-molybdenum alloy. The synergistic effect between nickel and reduced graphene oxide promoted hydrogen evolution, moreover, refined grain in nickel-reduced graphene oxide composite coating and large specific surface of reduced graphene oxide also facilitated hydrogen evolution reaction.

  9. Investigation of hydrogen evolution activity for the nickel, nickel-molybdenum nickel-graphite composite and nickel-reduced graphene oxide composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jinlong, Lv, E-mail: ljlbuaa@126.com [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Tongxiang, Liang; Chen, Wang [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China)

    2016-03-15

    Graphical abstract: - Highlights: • Improved HER efficiency of Ni-Mo coatings was attributed to ‘cauliflower’ like microstructure. • RGO in nickel-RGO composite coating promoted refined grain and facilitated HER. • Synergistic effect between nickel and RGO facilitated HER due to large specific surface of RGO. - Abstract: The nickel, nickel-molybdenum alloy, nickel-graphite and nickel-reduced graphene oxide composite coatings were obtained by the electrodeposition technique from a nickel sulfate bath. Nanocrystalline molybdenum, graphite and reduced graphene oxide in nickel coatings promoted hydrogen evolution reaction in 0.5 M H{sub 2}SO{sub 4} solution at room temperature. However, the nickel-reduced graphene oxide composite coating exhibited the highest electrocatalytic activity for the hydrogen evolution reaction in 0.5 M H{sub 2}SO{sub 4} solution at room temperature. A large number of gaps between ‘cauliflower’ like grains could decrease effective area for hydrogen evolution reaction in slight amorphous nickel-molybdenum alloy. The synergistic effect between nickel and reduced graphene oxide promoted hydrogen evolution, moreover, refined grain in nickel-reduced graphene oxide composite coating and large specific surface of reduced graphene oxide also facilitated hydrogen evolution reaction.

  10. Effects of reaction temperature and inlet oxidizing gas flow rate on IG-110 graphite oxidation used in HTR-PM

    International Nuclear Information System (INIS)

    Sun Ximing; Dong Yujie; Zhou Yangping; Shi Lei; Sun Yuliang; Zhang Zuoyi; Li Zhengcao

    2017-01-01

    The oxidation behavior of a selected nuclear graphite (IG-110) used in Pebble-bed Module High Temperature gas-cooled Reactor was investigated under the condition of air ingress accident. The oblate rectangular specimen was oxidized by oxidant gas with oxygen mole fraction of 20% and flow rates of 125–500 ml/min at temperature of 400–1200°C. Experiment results indicate that the oxidation behavior can also be classified into three regimes according to temperature. The regime I at 400–550°C has lower apparent activation energies of 75.57–138.59 kJ/mol when the gas flow rate is 125–500 ml/min. In the regime II at 600–900°C, the oxidation rate restricted by the oxygen supply to graphite is almost stable with the increase of temperature. In the regime III above 900°C, the oxidation rate increases obviously with the increase of temperature.With the increase of inlet gas flow from 125 to 500 ml/min, the apparent activation energy in regime I is increased and the stableness of oxidation rate in regime II is reduced. (author)

  11. Coal pyrolysis under synthesis gas, hydrogen and nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ariunaa, A.; Li Bao-Qing; Li Wen; Purevsuren, B. (and others) [Chinese Academy of Sciences, Taiyuan (China)

    2007-02-15

    Chinese Xundian, Mongolian Shiveeovoo lignites and Khoot oil shale are pyrolyzed under synthesis gas (SG) at temperature range from 400 to 800{sup o}C for lignite and from 300 to 600{sup o}C for oil shale with heating rate of 10{sup o}C/min in a fixed bed reactor. The results were compared with those obtained by pyrolysis under hydrogen and nitrogen. The results showed that unlike pyrolysis at high pressure, there are only slight different in the yields of char and tar among pyrolyses under various gases at room pressure for lignite, while higher liquid yield with lower yields of char and gas was obtained in pyrolysis of oil shale under SG and H{sub 2} than under N{sub 2}. It is found that the pyrite S can be easily removed to partially convert to organic S under various gaseous atmosphere and the total sulfur removal for oil shale is much less than lignite, which might be related to its high ash content. The higher total sulfur removal and less organic S content in the presence of SG in comparison with those under N{sub 2} and even under H{sub 2} in pyrolysis of Xundian lignite might result from the action of CO in SG. However, CO does not show its function in pyrolysis of Khoot oil shale, which might also be related to the high ash content. The results reported show the possibility of using synthesis gas instead of pure hydrogen as the reactive gas for coal hydropyrolysis. 11 refs., 4 figs., 6 tabs.

  12. Improvement of anaerobic bio-hydrogen gas production from organic sludge waste

    International Nuclear Information System (INIS)

    Lee, S.; Lee, Y. H.

    2009-01-01

    Microbial hydrogen gas production from organic matters stands out as one of the most promising alternatives for sustainable green energy production. Based on the literature review, investigation of anaerobic bio-hydrogen gas production from organic sludge waste using a mixed culture has been very limited. The objective of this study was to assess the anaerobic bio-hydrogen gas production from organic sludge waste under various conditions. (Author)

  13. Study on atmospheric hydrogen enrichment by cryopump method and isotope separation by gas chromatography

    International Nuclear Information System (INIS)

    Taniyama, Yuki; Momoshima, Noriyuki

    2001-01-01

    To obtain the information of source of atmospheric hydrogen tritium an analysis of tritium isotopes is thought to be effective. So an atmospheric hydrogen enrichment apparatus and a cryogenic gas chromatographic column were made. Experiments were carried out to study the performance of cryopump to enrich atmospheric hydrogen and the column to separate hydrogen isotopes that obtained by cryopump method. The cryopump was able to process about 1000 1 atmosphere and the column was able to separate hydrogen isotopes with good resolution. (author)

  14. A comparative economic assessment of hydrogen production from coke oven gas, water electrolysis and steam reforming of natural gas

    International Nuclear Information System (INIS)

    Nguyen, Y.V.; Ngo, Y.A.; Tinkler, M.J.; Cowan, N.

    2003-01-01

    This paper presents the comparative economics of producing hydrogen for the hydrogen economy by recovering it from waste gases from the steel industry, by water electrolysis and by conventional steam reforming of natural gas. Steel makers produce coke for their blast furnace operation by baking coal at high temperature in a reduced environment in their coke ovens. These ovens produce a coke oven gas from the volatiles in the coal. The gas, containing up to 60% hydrogen, is commonly used for its heating value with some of it being flared. The feasibility of recovering this hydrogen from the gas will be presented. A comparison of this opportunity with that of hydrogen from water electrolysis using low cost off-peak electricity from nuclear energy will be made. The impact of higher daily average electricity rate in Ontario will be discussed. The benefits of these opportunities compared with those from conventional steam reforming of natural gas will be highlighted. (author)

  15. Hydrogen rich gas production by thermocatalytic decomposition of kenaf biomass

    Energy Technology Data Exchange (ETDEWEB)

    Irmak, Sibel; Oeztuerk, ilker [Department of Chemistry, Cukurova University, Arts and Sciences Faculty, Adana 01330 (Turkey)

    2010-06-15

    Kenaf (Hibiscus cannabinus L.), a well known energy crop and an annual herbaceous plant grows very fast with low lodging susceptibility was used as representative lignocellulosic biomass in the present work. Thermocatalytic conversions were performed by aqueous phase reforming (APR) of kenaf hydrolysates and direct gasification of solid biomass of kenaf using 5% Pt on activated carbon as catalyst. Hydrolysates used in APR experiments were prepared by solubilization of kenaf biomass in subcritical water under CO{sub 2} gas pressure. APR of kenaf hydrolysate with low molecular weight polysaccharides in the presence of the reforming catalyst produced more gas compared to the hydrolysate that had high molecular weight polysaccharides. APR experiments of kenaf biomass hydrolysates and glucose, which was used as a simplest biomass model compound, in the presence of catalyst produced various amounts of gas mixtures that consisted of H{sub 2}, CO, CO{sub 2}, CH{sub 4} and C{sub 2}H{sub 6}. The ratios of H{sub 2} to other gases produced were 0.98, 1.50 and 1.35 for 150 C and 250 C subcritical water-treated kenaf hydrolysates and glucose, respectively. These ratios indicated that more the degraded organic content of kenaf hydrolysate the better selectivity for hydrogen production. Although APR of 250 C-kenaf hydrolysate resulted in similar gas content and composition as glucose, the gas volume produced was three times higher in glucose feed. The use of solid kenaf biomass as starting feedstock in APR experiments resulted in less gas production since the activity of catalyst was lowered by solid biomass particles. (author)

  16. Graphitic carbon nitride nanosheet for photocatalytic hydrogen production: The impact of morphology and element composition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhao; Zhang, Yijie [Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and Chemistry, China University of Geosciences Wuhan, 388 Lumo Road, Wuhan 430074 (China); Lu, Luhua, E-mail: lhlu@cug.edu.cn [Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and Chemistry, China University of Geosciences Wuhan, 388 Lumo Road, Wuhan 430074 (China); Zhejiang institute, China University of Geosciences Wuhan, Hangzhou 311305 (China); Si, Yanjie; Zhang, Si [Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and Chemistry, China University of Geosciences Wuhan, 388 Lumo Road, Wuhan 430074 (China); Chen, Ying [Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and Chemistry, China University of Geosciences Wuhan, 388 Lumo Road, Wuhan 430074 (China); Zhejiang institute, China University of Geosciences Wuhan, Hangzhou 311305 (China); Dai, Kai, E-mail: daikai94@ustc.edu.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Duan, Ping [Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and Chemistry, China University of Geosciences Wuhan, 388 Lumo Road, Wuhan 430074 (China); Zhejiang institute, China University of Geosciences Wuhan, Hangzhou 311305 (China); Duan, Limei [Inner Mongolia Key Lab of Chemistry of Natural Products and Synthesis of Functional Molecules, College of Chemistry and Chemical Engineering, Inner Mongolia University for the Nationalities, Tongliao 028000 (China); Liu, Jinghai, E-mail: jhliu2008@sinano.ac.cn [Inner Mongolia Key Lab of Chemistry of Natural Products and Synthesis of Functional Molecules, College of Chemistry and Chemical Engineering, Inner Mongolia University for the Nationalities, Tongliao 028000 (China)

    2017-01-01

    Highlights: • g-C{sub 3}N{sub 4} with tunable morphology was prepared by varying pyrolysis time. • g-C{sub 3}N{sub 4} showed reduced recombination of photogenerated electrons and holes. • g-C{sub 3}N{sub 4} showed enhanced photocatalytic hydrogen evolution activity. - Abstract: The intrinsic morphology and basal plane defects on g-C{sub 3}N{sub 4} nanosheet have important influences on its electronic structures and photocatalytic activity. In this work, we report extending thermal treatment time of g-C{sub 3}N{sub 4} at 550 °C not only change the morphology of g-C{sub 3}N{sub 4} but also element composition of g-C{sub 3}N{sub 4}. The morphology variation results in largely increased SSA from 40.22 to 117.27 m{sup 2} g{sup −1}, obviously reduced pore size from 3.99 to 2.77 nm for g-C{sub 3}N{sub 4} and formation of in-plane holes. Moreover, composition variation of g-C{sub 3}N{sub 4} has also been found to have changed as the pyrolysis time extended. These changes have significant impact on the optical properties and photoelectrical characters of g-C{sub 3}N{sub 4}, which were investigated by UV-DSR, PL and Photocurrent measurement. The photocatalytic activity of g-C{sub 3}N{sub 4} obtained via 9 h thermal treatment at 550 °C has shown highest photocatalytic activity, which is 1.77 times than that of g-C{sub 3}N{sub 4} obtained via 3 h thermal treatment under visible irradiation and 1.99 times under UV irradiation respectively.

  17. Graphitic carbon nitride nanosheet for photocatalytic hydrogen production: The impact of morphology and element composition

    International Nuclear Information System (INIS)

    Zhang, Zhao; Zhang, Yijie; Lu, Luhua; Si, Yanjie; Zhang, Si; Chen, Ying; Dai, Kai; Duan, Ping; Duan, Limei; Liu, Jinghai

    2017-01-01

    Highlights: • g-C_3N_4 with tunable morphology was prepared by varying pyrolysis time. • g-C_3N_4 showed reduced recombination of photogenerated electrons and holes. • g-C_3N_4 showed enhanced photocatalytic hydrogen evolution activity. - Abstract: The intrinsic morphology and basal plane defects on g-C_3N_4 nanosheet have important influences on its electronic structures and photocatalytic activity. In this work, we report extending thermal treatment time of g-C_3N_4 at 550 °C not only change the morphology of g-C_3N_4 but also element composition of g-C_3N_4. The morphology variation results in largely increased SSA from 40.22 to 117.27 m"2 g"−"1, obviously reduced pore size from 3.99 to 2.77 nm for g-C_3N_4 and formation of in-plane holes. Moreover, composition variation of g-C_3N_4 has also been found to have changed as the pyrolysis time extended. These changes have significant impact on the optical properties and photoelectrical characters of g-C_3N_4, which were investigated by UV-DSR, PL and Photocurrent measurement. The photocatalytic activity of g-C_3N_4 obtained via 9 h thermal treatment at 550 °C has shown highest photocatalytic activity, which is 1.77 times than that of g-C_3N_4 obtained via 3 h thermal treatment under visible irradiation and 1.99 times under UV irradiation respectively.

  18. Study of new structures adapted to gas-graphite and gas-heavy water reactors; Etude de structures nouvelles adaptees aux reacteurs graphite-gaz et eau lourde-gaz

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R; Roche, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The experience acquired as a result of the operation of the Marcoule reactors and of the construction and start-up of the E.D.F. reactors on the one hand, and the conclusions of research and tests carried out out-of-pile on the other hand, lead to a considerable change in the general design of reactors of the gas-graphite type. The main modifications envisaged are analysed in the paper. The adoption of an annular fuel element and of a down-current cooling will make it possible to increase considerably the specific power and the power output of each channel; as a result there will be a considerable reduction in the number of the channels and a corresponding increase in the size of the unit cell. The graphite stack will have to be adapted to there new conditions. For security reasons, the use of prestressed concrete for the construction of the reactor vessel is becoming more widespread; they could lead to the exchangers and the fuel-handling apparatus becoming integrated inside the vessel (the so-called 'attic' device). A full-size mode) of this attic has been built at Saclay with the participation of EURATOM; the operational results obtained are presented as well as a new original design for the control rods. As for as the gas-heavy-water system is concerned, the research is carried out on two points of design; the first, which retains the use of horizontal pressure tubes, takes into account the experience acquired during the construction of the EL 4 reactor of which it will constitute an extrapolation; the second, arising from the research carried out on the gas-graphite system, will use a pre-stressed concrete vessel for holding the pressure, the moderator being almost at the same pressure as the cooling fluid and the fuel being placed in vertical channels. The relative merits of these two variants are analysed in the present paper. (authors) [French] L'experience acquise par l'exploitation des reacteurs de MARCOULE, la construction et le demarrage des reacteurs d

  19. Determination of hydrogen in uranium-niobium-zirconium alloy by inert-gas fusion

    International Nuclear Information System (INIS)

    Carden, W.F.

    1979-12-01

    An improved method has been developed using inert-gas fusion for determining the hydrogen content in uranium-niobium-zirconium (U-7.5Nb-2.5Zr) alloy. The method is applicable to concentrations of hydrogen ranging from 1 to 250 micrograms per gram and may be adjusted for analysis of greater hydrogen concentrations. Hydrogen is determined using a hydrogen determinator. The limit of error for a single determination at the 95%-confidence level (at the 3.7-μg/g-hydrogen level) is +-1.4 micrograms per gram hydrogen

  20. Some economic aspects of natural uranium graphite gas reactor types. Present status and trends of costs in France

    International Nuclear Information System (INIS)

    Gaussens, J.; Tanguy, P.

    1964-01-01

    The first part of this report defines the economic advantages of natural uranium fuels, which are as follows: the restricted number and relatively simple fabrication processes of the fuel elements, the low cost per kWh of the finished product and the reasonable capital investments involved in this type of fuel cycle as compared to that of enriched uranium. All these factors combine to reduce the arbitrary nature of cost estimates, which is particularly marked in the case of enriched uranium due to the complexity of its cycle and the uncertainties of plutonium prices). Finally, the wide availability of yellowcake, as opposed to the present day virtual monopoly of isotope separation, and the low cost of natural uranium stockpiling, offer appreciable guarantees in the way of security of supply and economic and political independence as compared with the use of enriched uranium. As far as overall capital investments are concerned, it is shown that, although graphite-gas reactor costs are higher than those of light water reactors in certain capacity ranges, the situation becomes far less clear when we start taking into account, in the interest of national independence, the cost of nuclear fuel production equipment in the case of each of these types of reactor. Finally, the marginal cost of the power capacity of a graphite-gas reactor is low and its technological limitations have receded (owing particularly to the use of prestressed concrete). It is a well known fact that the trend is now towards larger power station units, which means that the rentability of natural uranium graphite reactors as compared to other types of reactors will become more and more pronounced. The second section aims at presenting a realistic short and medium term view of the fuel, running, and investment costs of French natural uranium graphite gas, reactors. Finally, the economic goals which this type of reactor can reach in the very near future are given. It is thus shown that considerable

  1. First principles study of inert-gas (helium, neon, and argon) interactions with hydrogen in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Xiang-Shan [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Hou, Jie [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Li, Xiang-Yan [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Wu, Xuebang, E-mail: xbwu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Liu, C.S., E-mail: csliu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Chen, Jun-Ling; Luo, G.-N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2017-04-15

    We have systematically evaluated binding energies of hydrogen with inert-gas (helium, neon, and argon) defects, including interstitial clusters and vacancy-inert-gas complexes, and their stable configurations using first-principles calculations. Our calculations show that these inert-gas defects have large positive binding energies with hydrogen, 0.4–1.1 eV, 0.7–1.0 eV, and 0.6–0.8 eV for helium, neon, and argon, respectively. This indicates that these inert-gas defects can act as traps for hydrogen in tungsten, and impede or interrupt the diffusion of hydrogen in tungsten, which supports the discussion on the influence of inert-gas on hydrogen retention in recent experimental literature. The interaction between these inert-gas defects and hydrogen can be understood by the attractive interaction due to the distortion of the lattice structure induced by inert-gas defects, the intrinsic repulsive interaction between inert-gas atoms and hydrogen, and the hydrogen-hydrogen repelling in tungsten lattice.

  2. Detail Design of the hydrogen system and the gas blanketing system for the HANARO-CNS

    International Nuclear Information System (INIS)

    Choi, Jung Woon; Kim, Hark Rho; Kim, Young Ki; Wu, Sang Ik; Kim, Bong Su; Lee, Yong Seop

    2007-04-01

    The cold neutron source (CNS), which will be installed in the vertical CN hole of the reflector tank at HANARO, makes thermal neutrons to moderate into the cold neutrons with the ranges of 0.1 ∼ 10 meV passing through a moderator at about 22K. A moderator to produce cold neutrons is liquid hydrogen, which liquefies by the heat transfer with cryogenic helium flowing from the helium refrigeration system (HRS). Because of its installed location, the hydrogen system is designed to be surrounded by the gas blanketing system to notify the leakage on the system and to prevent hydrogen leakage out of the CNS. The hydrogen system, consisted of hydrogen charging unit, hydrogen storage unit, hydrogen buffer tank, and hydrogen piping, is designed to smoothly and safely supply hydrogen to and to draw back hydrogen from the IPA of the CNS under the HRS operation mode. Described is that calculation for total required hydrogen amount in the CNS as well as operation schemes of the hydrogen system. The gas blanketing system (GBS) is designed for the supply of the compressed nitrogen gas into the air pressurized valves for the CNS, to isolate the hydrogen system from the air and the water, and to prevent air or water intrusion into the vacuum system as well as the hydrogen system. All detail descriptions are shown inhere as well as the operation scheme for the GBS

  3. Device for removing hydrogen gas from the safety containment vessel of a nuclear reactor

    International Nuclear Information System (INIS)

    Stiefel, M.

    1983-01-01

    The safe processing of all concentrations of gas mixtures should be possible with such a device using a thermal recombiner of compact construction. A recombiner consisting of a metal case and diverter sheets situated in it is heated by induction. The incoming pipe for the gas mixture enriched with hydrogen and the outgoing pipe for the gas mixture with low hydrogen content are connected together by a three way valve. The third connection to the safety valve takes the larger port of the gas mixture with low hydrogen content back to the safety containment vessel. Sufficient amount of the gas mixture with low hydrogen content is taken via the three way valve to the safety containment vessel to ensure that the hydrogen content of the gas mixture taken to the recombiner remains below the 4% by volume limit. (orig./PW)

  4. A mathematical framework for modelling and evaluating natural gas pipeline networks under hydrogen injection

    Energy Technology Data Exchange (ETDEWEB)

    Tabkhi, F.; Azzaro-Pantel, C.; Pibouleau, L.; Domenech, S. [Laboratoire de Genie Chimique, UMR5503 CNRS/INP/UPS, 5 rue Paulin Talabot F-BP1301, 31106 Toulouse Cedex 1 (France)

    2008-11-15

    This article presents the framework of a mathematical formulation for modelling and evaluating natural gas pipeline networks under hydrogen injection. The model development is based on gas transport through pipelines and compressors which compensate for the pressure drops by implying mainly the mass and energy balances on the basic elements of the network. The model was initially implemented for natural gas transport and the principle of extension for hydrogen-natural gas mixtures is presented. The objective is the treatment of the classical fuel minimizing problem in compressor stations. The optimization procedure has been formulated by means of a nonlinear technique within the General Algebraic Modelling System (GAMS) environment. This work deals with the adaptation of the current transmission networks of natural gas to the transport of hydrogen-natural gas mixtures. More precisely, the quantitative amount of hydrogen that can be added to natural gas can be determined. The studied pipeline network, initially proposed in [1] is revisited here for the case of hydrogen-natural gas mixtures. Typical quantitative results are presented, showing that the addition of hydrogen to natural gas decreases significantly the transmitted power: the maximum fraction of hydrogen that can be added to natural gas is around 6 mass% for this example. (author)

  5. a Study of Using Hydrogen Gas for Steam Boiler in CHOLOR- Alkali Manufacturing

    Science.gov (United States)

    Peantong, Sasitorn; Tangjitsitcharoen, Somkiat

    2017-06-01

    Main products of manufacturing of Cholor - Alkali, which commonly known as industrial chemical, are chlorine gas (Cl2), Sodium Hydroxide (NaOH) and hydrogen gas (H2). Chorine gas and sodium hydroxide are two main products for commercial profit; where hydrogen gas is by product. Most industries release hydrogen gas to atmosphere as it is non-profitable and less commercial scale. This study aims to make the most use of hydrogen as a substitute energy of natural gas for steam boiler to save energy cost. The second target of this study is to reduce level of CO2 release to air as a consequence of boiler combustion. This study suggests to install boiler that bases on hydrogen as main power with a high turndown ratio of at least 1:6. However, this case study uses boiler with two mode such as natural gas (NG) mode and mixed mode as they need to be flexible for production. Never the less, the best boiler selection is to use single mode energy of hydrogen. The most concerned issue about hydrogen gas is explosion during combustion stage. Stabilization measures at emergency stop is introduced to control H2 pressure to protect the explosion. This study varies ratio of natural gas to hydrogen gas to find the optimal level of two energy sources for boiler and measure total consumption through costing model; where CO2 level is measured at the boiler stack. The result of this study shows that hydrogen gas can be a substitute energy with natural gas and can reduce cost. Natural gas cost saving is 248,846 baht per month and reduce level of NOx is 80 ppm 7% O2 and 2 % of CO2 release to air as a consequence of boiler combustion.

  6. Measurements of hydrogen concentration in liquid sodium by using an inert gas carrier method

    International Nuclear Information System (INIS)

    Funada, T.; Nihei, I.; Yuhara, S.; Nakasuji, T.

    1979-01-01

    A technique was developed to measure the hydrogen level in liquid sodium using an inert gas carrier method. Hydrogen was extracted into an inert gas from sodium through a thin nickel membrane in the form of a helically wound tube. The amount of hydrogen in the inert gas was analyzed by gas chromatography. The present method is unique in that it can be used over the wide range of sodium temperatures (150 to 700 0 C) and has no problems associated with vacuum systems. The partial pressure of hydrogen in sodium was determined as a function of cold-trap temperature (T/sub c/). Sieverts' constant (K/sub s/) was determined as a function of sodium temperature (T). From Sieverts' constant, the solubility of hydrogen in sodium is calculated. It was found that other impurities in sodium, such as (O) and (OH), have little effect on the hydrogen pressure in the sodium loop

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

    Science.gov (United States)

    Alghamdi, Abdulaziz

    2009-12-01

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

  8. Method of carbon dioxide-free hydrogen production from hydrocarbon decomposition over metal salts

    Science.gov (United States)

    Erlebacher, Jonah; Gaskey, Bernard

    2017-10-03

    A process to decompose methane into carbon (graphitic powder) and hydrogen (H.sub.2 gas) without secondary production of carbon dioxide, employing a cycle in which a secondary chemical is recycled and reused, is disclosed.

  9. Producing hydrogen from coke-oven gas: the Solmer project. [PSA process

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, G; Vidal, J

    1984-05-01

    After presenting the energy situation at the Solmer plant, where coke-oven gas is produced to excess, the authors examine the technical and economic possibilities of utilizing this gas for hydrogen extraction. They describe a project (based on the PSA process) for producing some 65 t/d of hydrogen and present the technical features of the scheme. An evaluation of the energy and financial costs of producing the hydrogen confirms the competitive status of the process.

  10. Upgrade to the Cryogenic Hydrogen Gas Target Monitoring System

    Science.gov (United States)

    Slater, Michael; Tribble, Robert

    2013-10-01

    The cryogenic hydrogen gas target at Texas A&M is a vital component for creating a secondary radioactive beam that is then used in experiments in the Momentum Achromat Recoil Spectrometer (MARS). A stable beam from the K500 superconducting cyclotron enters the gas cell and some incident particles are transmuted by a nuclear reaction into a radioactive beam, which are separated from the primary beam and used in MARS experiments. The pressure in the target chamber is monitored so that a predictable isotope production rate can be assured. A ``black box'' received the analog pressure data and sent RS232 serial data through an outdated serial connection to an outdated Visual Basic 6 (VB6) program, which plotted the chamber pressure continuously. The black box has been upgraded to an Arduino UNO microcontroller [Atmel Inc.], which can receive the pressure data and output via USB to a computer. It has been programmed to also accept temperature data for future upgrade. A new computer program, with updated capabilities, has been written in Python. The software can send email alerts, create audible alarms through the Arduino, and plot pressure and temperature. The program has been designed to better fit the needs of the users. Funded by DOE and NSF-REU Program.

  11. Shock-wave proton acceleration from a hydrogen gas jet

    Science.gov (United States)

    Cook, Nathan; Pogorelsky, Igor; Polyanskiy, Mikhail; Babzien, Marcus; Tresca, Olivier; Maharjan, Chakra; Shkolnikov, Peter; Yakimenko, Vitaly

    2013-04-01

    Typical laser acceleration experiments probe the interaction of intense linearly-polarized solid state laser pulses with dense metal targets. This interaction generates strong electric fields via Transverse Normal Sheath Acceleration and can accelerate protons to high peak energies but with a large thermal spectrum. Recently, the advancement of high pressure amplified CO2 laser technology has allowed for the creation of intense (10^16 Wcm^2) pulses at λ˜10 μm. These pulses may interact with reproducible, high rep. rate gas jet targets and still produce plasmas of critical density (nc˜10^19 cm-3), leading to the transference of laser energy via radiation pressure. This acceleration mode has the advantage of producing narrow energy spectra while scaling well with pulse intensity. We observe the interaction of an intense CO2 laser pulse with an overdense hydrogen gas jet. Using two pulse optical probing in conjunction with interferometry, we are able to obtain density profiles of the plasma. Proton energy spectra are obtained using a magnetic spectrometer and scintillating screen.

  12. Attenuation of hydrogen radicals traveling under flowing gas conditions through tubes of different materials

    International Nuclear Information System (INIS)

    Grubbs, R.K.; George, S.M.

    2006-01-01

    Hydrogen radical concentrations traveling under flowing gas conditions through tubes of different materials were measured using a dual thermocouple probe. The source of the hydrogen radicals was a toroidal radio frequency plasma source operating at 2.0 and 3.3 kW for H 2 pressures of 250 and 500 mTorr, respectively. The dual thermocouple probe was comprised of exposed and covered Pt/Pt13%Rh thermocouples. Hydrogen radicals recombined efficiently on the exposed thermocouple and the energy of formation of H 2 heated the thermocouple. The second thermocouple was covered by glass and was heated primarily by the ambient gas. The dual thermocouple probe was translated and measured temperatures at different distances from the hydrogen radical source. These temperature measurements were conducted at H 2 flow rates of 35 and 75 SCCM (SCCM denotes cubic centimeter per minute at STP) inside cylindrical tubes made of stainless steel, aluminum, quartz, and Pyrex. The hydrogen radical concentrations were obtained from the temperatures of the exposed and covered thermocouples. The hydrogen concentration decreased versus distance from the plasma source. After correcting for the H 2 gas flow using a reference frame transformation, the hydrogen radical concentration profiles yielded the atomic hydrogen recombination coefficient, γ, for the four materials. The methodology of measuring the hydrogen radical concentrations, the analysis of the results under flowing gas conditions, and the determination of the atomic hydrogen recombination coefficients for various materials will help facilitate the use of hydrogen radicals for thin film growth processes

  13. Hydrogen-enriched natural gas; Bridge to an ultra low carbon world

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Joshua; Oliver, Mike

    2010-09-15

    Natural gas is recognized as an important part of the solution to climate change, as it has the smallest carbon footprint among fossil fuels and can be used with high efficiency. This alone is not enough. Supplementing natural gas with hydrogen creating hydrogen-enriched natural gas (HENG), where the hydrogen comes from a low- or zero-carbon energy source. HENG, the subject of this paper, can leverage existing natural gas infrastructure to reduce CO2 and NOx, improve the efficiency of end-use equipment, and lower the overall carbon intensity of energy consumption.

  14. Hydrogen Production by Steam Reforming of Natural Gas Over Vanadium-Nickel-Alumina Catalysts.

    Science.gov (United States)

    Yoo, Jaekyeong; Park, Seungwon; Song, Ji Hwan; Song, In Kyu

    2018-09-01

    A series of vanadium-nickel-alumina (xVNA) catalysts were prepared by a single-step sol-gel method with a variation of vanadium content (x, wt%) for use in the hydrogen production by steam reforming of natural gas. The effect of vanadium content on the physicochemical properties and catalytic activities of xVNA catalysts in the steam reforming of natural gas was investigated. It was found that natural gas conversion and hydrogen yield showed volcano-shaped trends with respect to vanadium content. It was also revealed that natural gas conversion and hydrogen yield increased with decreasing nickel crystallite size.

  15. Status of Chronic Oxidation Studies of Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mee, Robert W. [Univ. of Tennessee, Knoxville, TN (United States)

    2016-05-01

    Graphite will undergo extremely slow, but continuous oxidation by traces of moisture that will be present, albeit at very low levels, in the helium coolant of HTGR. This chronic oxidation may cause degradation of mechanical strength and thermal properties of graphite components if a porous oxidation layer penetrates deep enough in the bulk of graphite components during the lifetime of the reactor. The current research on graphite chronic oxidation is motivated by the acute need to understand the behavior of each graphite grade during prolonged exposure to high temperature chemical attack by moisture. The goal is to provide the elements needed to develop predictive models for long-time oxidation behavior of graphite components in the cooling helium of HTGR. The tasks derived from this goal are: (1) Oxidation rate measurements in order to determine and validate a comprehensive kinetic model suitable for prediction of intrinsic oxidation rates as a function of temperature and oxidant gas composition; (2) Characterization of effective diffusivity of water vapor in the graphite pore system in order to account for the in-pore transport of moisture; and (3) Development and validation of a predictive model for the penetration depth of the oxidized layer, in order to assess the risk of oxidation caused damage of particular graphite grades after prolonged exposure to the environment of helium coolant in HTGR. The most important and most time consuming of these tasks is the measurement of oxidation rates in accelerated oxidation tests (but still under kinetic control) and the development of a reliable kinetic model. This report summarizes the status of chronic oxidation studies on graphite, and then focuses on model development activities, progress of kinetic measurements, validation of results, and improvement of the kinetic models. Analysis of current and past results obtained with three grades of showed that the classical Langmuir-Hinshelwood model cannot reproduce all

  16. Serpentinization and the origin of hydrogen gas in Kansas

    Energy Technology Data Exchange (ETDEWEB)

    Coveney, R.M. Jr.; Goebel, E.D.; Zeller, E.J.; Dreschhoff, G.A.M.; Angino, E.E.

    1987-01-01

    Hydrogen gas occurs in ten Kansas wells near the Mid-Continent rift system. Since 1982, two wells have yielded small amounts of gases containing an average of 29-37 mole % H/sub 2/, the remainder being chiefly N/sub 2/ with only traces of hydrocarbons. Isotopic compositions for hydrogen (delta D = -740 to -836 per thousand) imply near-ambient (about 10/sup 0/C) equilibration temperatures for the gases, which are among the most deuterium-depleted in nature and resemble the H/sub 2/-rich gases described from ophiolites in Oman. Isotopic values for the Kansas N/sub 2/ differ slightly from those of the atmosphere, but not enough to rule out an atmospheric origin. Because they are low in CH/sub 4/ and CO/sub 2/, expected byproducts of biogenic activity, the gases are probably abiogenic in origin. The existence of such gases near a major rift system, containing mafic rocks, and not far from known kimberlites is consistent with an origin from reactions involving Fe/sup +2/ oxidation, for example during serpentinization. Because the gases may be associated with kimberlites and deep-seated rifting, mantle outgassing is possible, but such an origin would be difficult to reconcile with the low isotopic temperatures. The H/sub 2/ gases from Kansas (and elsewhere) seem to be too low in pressure to have commercial value. However, neither the Kansas gases nor those from other H/sub 2/ occurrences have been adequately examined to assess their importance as potential resources. 4 figures, 3 tables.

  17. Lifecycle impacts of natural gas to hydrogen pathways on urban air quality

    International Nuclear Information System (INIS)

    Wang, Guihua; Ogden, Joan M.; Nicholas, Michael A.

    2007-01-01

    In this paper we examine the potential air quality impacts of hydrogen transportation fuel from a lifecycle analysis perspective, including impacts from fuel production, delivery, and vehicle use. We assume that hydrogen fuel cell vehicles are introduced in a specific region, Sacramento County, California. We consider two levels of market penetration where 9% or 20% of the light duty fleet are hydrogen fuel cell vehicles. The following three natural gas to hydrogen supply pathways are assessed in detail and compared in terms of emissions and the resulting changes in ambient air quality: (1) onsite hydrogen production; (2) centralized hydrogen production with gaseous hydrogen pipeline delivery systems; and (3) centralized hydrogen production with liquid hydrogen truck delivery systems. All the pathways examined use steam methane reforming (SMR) of natural gas to produce hydrogen. The source contributions to incremental air pollution are estimated and compared among hydrogen pathways. All of the hydrogen pathways result in extremely low contributions to ambient air concentrations of NO x , CO, particulates, and SO x , typically less than 0.1% of the current ambient pollution for both levels of market penetration. Among the hydrogen supply options, it is found that the central SMR with pipeline delivery systems is the lowest pollution option available provided the plant is located to avoid transport of pollutants into the city via prevailing winds. The onsite hydrogen pathway is comparable to the central hydrogen pathway with pipeline systems in terms of the resulting air pollution. The pathway with liquid hydrogen trucks has a greater impact on air quality relative to the other pathways due to emissions associated with diesel trucks and electricity consumption to liquefy hydrogen. However, all three hydrogen pathways result in negligible air pollution in the region. (author)

  18. Apparatus and method for treating pollutants in a gas using hydrogen peroxide and UV light

    Science.gov (United States)

    Cooper, Charles David (Inventor); Clausen, Christian Anthony (Inventor)

    2005-01-01

    An apparatus for treating pollutants in a gas may include a source of hydrogen peroxide, and a treatment injector for creating and injecting dissociated hydrogen peroxide into the flow of gas. The treatment injector may further include an injector housing having an inlet, an outlet, and a hollow interior extending therebetween. The inlet may be connected in fluid communication with the source of hydrogen peroxide so that hydrogen peroxide flows through the hollow interior and toward the outlet. At least one ultraviolet (UV) lamp may be positioned within the hollow interior of the injector housing. The at least one UV lamp may dissociate the hydrogen peroxide flowing through the tube. The dissociated hydrogen peroxide may be injected into the flow of gas from the outlet for treating pollutants, such as nitrogen oxides.

  19. Melting of contaminated steel scrap from the dismantling of the CO2 systems of gas cooled, graphite moderated nuclear reactors

    International Nuclear Information System (INIS)

    Feaugas, J.; Jeanjacques, M.; Peulve, J.

    1994-01-01

    G2 and G3 are the natural Uranium cooled reactors Graphite/Gas. The two reactors were designed for both plutonium and electricity production (45 MWe). The dismantling of the reactors at stage 2 has produced more than 4 000 tonnes of contaminated scrap. Because of their large mass and low residual contamination level, the French Atomic Energy Commission (CEA) considered various possibilities for the processing of these metallic products in order to reduce the volume of waste going to be stored. After different studies and tests of several processes and the evaluation of their results, the choice to melt the dismantled pipeworks was taken. It was decided to build the Nuclear Steel Melting Facility known as INFANTE, in cooperation with a steelmaker (AHL). The realization time schedule for the INFANTE lasted 20 months. It included studies, construction and the licensing procedure. (authors). 2 tabs., 3 figs

  20. Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

    Directory of Open Access Journals (Sweden)

    Sangchoel Kim

    2013-10-01

    Full Text Available We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5 layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

  1. The production of high dose hydrogen gas by the AMS-H-01 for treatment of disease

    OpenAIRE

    Richard Camara; Lei Huang; John H Zhang

    2016-01-01

    Hydrogen gas is a new and promising treatment option for a variety of diseases including stroke. Here, we introduce the AMS-H-01, a medically approved machine capable of safely producing ~66% hydrogen gas. Furthermore, we propose the significance of this machine in the future of hydrogen gas research.

  2. The Influences of Time and Velocity of Inert Gas on the Quality of theProcessing Product of Graphite Matrix on the Baking Step

    International Nuclear Information System (INIS)

    Imam-Dahroni; Dwi-Herwidhi; NS, Kasilani

    2000-01-01

    The research of the synthesis of matrix graphite on the step of bakingprocess was conducted, by focusing on the influence of time and velocityvariables of the inert gas. The investigation on baking times ranging from 5minutes to 55 minutes and by varying the velocity of inert gas from 0.30l/minute to 3.60 l/minute, resulted the product of different matrix.Optimizing at the time of operation and the flow rate of argon gas indicatedthat the baking time for 30 minutes and by the flow rate of argon gas of 2.60l/minute resulted best matrix graphite that has a hardness value of 11kg/mm 2 of hardness and the ductility of 1800 Newton. (author)

  3. Hydrogen enriched gas production in a multi-stage downdraft gasification process

    International Nuclear Information System (INIS)

    Dutta, A.; Jarungthammachote, S.

    2009-01-01

    To achieve hydrogen enriched and low-tar producer gas, multi-stage air-blown and air-steam gasification were studied in this research. Results showed that the tar content from multi-stage air-blown and air-steam gasification was lower compared to the average value of that from downdraft gasification. It was also seen that an air-steam gasification process could potentially increase the hydrogen concentration in the producer gas in the expense of carbon monoxide; however, the summation of hydrogen and carbon monoxide in the producer gas was increased. (author)

  4. Recommendations on X80 steel for the design of hydrogen gas transmission pipelines

    International Nuclear Information System (INIS)

    Briottet, L.; Batisse, R.; De Dinechin, G.; Langlois, P.; Thiers, L.

    2012-01-01

    By limiting the pipes thickness necessary to sustain high pressure, high-strength steels could prove economically relevant for transmitting large gas quantities in pipelines on long distance. Up to now, the existing hydrogen pipelines have used lower-strength steels to avoid any hydrogen embrittlement. The CATHY-GDF project, funded by the French National Agency for Research, explored the ability of an industrial X80 grade for the transmission of pressurized hydrogen gas in large diameter pipelines. This project has developed experimental facilities to test the material under hydrogen gas pressure. Indeed, tensile, toughness, crack propagation and disc rupture tests have been performed. From these results, the effect of hydrogen pressure on the size of some critical defects has been analyzed allowing proposing some recommendations on the design of X80 pipe for hydrogen transport. Cost of Hydrogen transport could be several times higher than natural gas one for a given energy amount. Moreover, building hydrogen pipeline using high grade steels could induce a 10 to 40% cost benefit instead of using low grade steels, despite their lower hydrogen susceptibility. (authors)

  5. Performance Improvement of V-Fe-Cr-Ti Solid State Hydrogen Storage Materials in Impure Hydrogen Gas.

    Science.gov (United States)

    Ulmer, Ulrich; Oertel, Daria; Diemant, Thomas; Bonatto Minella, Christian; Bergfeldt, Thomas; Dittmeyer, Roland; Behm, R Jürgen; Fichtner, Maximilian

    2018-01-17

    Two approaches of engineering surface structures of V-Ti-based solid solution hydrogen storage alloys are presented, which enable improved tolerance toward gaseous oxygen (O 2 ) impurities in hydrogen (H 2 ) gas. Surface modification is achieved through engineering lanthanum (La)- or nickel (Ni)-rich surface layers with enhanced cyclic stability in an H 2 /O 2 mixture. The formation of a Ni-rich surface layer does not improve the cycling stability in H 2 /O 2 mixtures. Mischmetal (Mm, a mixture of La and Ce) agglomerates are observed within the bulk and surface of the alloy when small amounts of this material are added during arc melting synthesis. These agglomerates provide hydrogen-transparent diffusion pathways into the bulk of the V-Ti-Cr-Fe hydrogen storage alloy when the remaining oxidized surface is already nontransparent for hydrogen. Thus, the cycling stability of the alloy is improved in an O 2 -containing hydrogen environment as compared to the same alloy without addition of Mm. The obtained surface-engineered storage material still absorbs hydrogen after 20 cycles in a hydrogen-oxygen mixture, while the original material is already deactivated after 4 cycles.

  6. Basic study on high temperature gas cooled reactor technology for hydrogen production

    International Nuclear Information System (INIS)

    Chang, Jong Hwa; Lee, W. J.; Lee, H. M.

    2003-01-01

    The annual production of hydrogen in the world is about 500 billion m 3 . Currently hydrogen is consumed mainly in chemical industries. However hydrogen has huge potential to be consumed in transportation sector in coming decades. Assuming that 10% of fossil energy in transportation sector is substituted by hydrogen in 2020, the hydrogen in the sector will exceed current hydrogen consumption by more than 2.5 times. Currently hydrogen is mainly produced by steam reforming of natural gas. Steam reforming process is chiefest way to produce hydrogen for mass production. In the future, hydrogen has to be produced in a way to minimize CO2 emission during its production process as well as to satisfy economic competition. One of the alternatives to produce hydrogen under such criteria is using heat source of high-temperature gas-cooled reactor. The high-temperature gas-cooled reactor represents one type of the next generation of nuclear reactors for safe and reliable operation as well as for efficient and economic generation of energy

  7. Kinetics of Chronic Oxidation of NBG-17 Nuclear Graphite by Water Vapor

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burchell, Timothy D [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mee, Robert [Univ. of Tennessee, Knoxville, TN (United States)

    2015-05-01

    This report presents the results of kinetic measurements during accelerated oxidation tests of NBG-17 nuclear graphite by low concentration of water vapor and hydrogen in ultra-high purity helium. The objective is to determine the parameters in the Langmuir-Hinshelwood (L-H) equation describing the oxidation kinetics of nuclear graphite in the helium coolant of high temperature gas-cooled reactors (HTGR). Although the helium coolant chemistry is strictly controlled during normal operating conditions, trace amounts of moisture (predictably < 0.2 ppm) cannot be avoided. Prolonged exposure of graphite components to water vapor at high temperature will cause very slow (chronic) oxidation over the lifetime of graphite components. This behavior must be understood and predicted for the design and safe operation of gas-cooled nuclear reactors. The results reported here show that, in general, oxidation by water of graphite NBG-17 obeys the L-H mechanism, previously documented for other graphite grades. However, the characteristic kinetic parameters that best describe oxidation rates measured for graphite NBG-17 are different than those reported previously for grades H-451 (General Atomics, 1978) and PCEA (ORNL, 2013). In some specific conditions, certain deviations from the generally accepted L-H model were observed for graphite NBG-17. This graphite is manufactured in Germany by SGL Carbon Group and is a possible candidate for the fuel elements and reflector blocks of HTGR.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-29

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

  9. Adsorption removal of hydrogen sulfide gas. IV. Characteristics of adsorbents for the adsorption removal of hydrogen sulfide gas

    Energy Technology Data Exchange (ETDEWEB)

    Boki, K

    1974-10-25

    The amount of hydrogen sulfide gas adsorbed was affected by the surface properties (surface pH, acid strength, acid amount, and basic amount), the surface structure (pore volume), and the surface form (scanning electron microscopic observation) of 32 tested adsorbents. In general, the amount adsorption increased in the following order, amount of H/sub 2/S adsorbed on the silicate adsorbents, on the active carbon adsorbents, and on the zeolite adsorbents. The amount of H/sub 2/S adsorbed on magnesium silicate and silica gel adsorbents was mainly affected by the surface structure, and the amount adsorbed on the aluminum silicate adsorbents was affected by the distinctions on the surface forms of the adsorbents. The amount of H/sub 2/S adsorbed on 10 kinds of active carbon was determined by the surface properties and the surface structures of the adsorbents. The amount adsorbed on 12 kinds of zeolites was determined by either the surface properties or by the surface structures of the adsorbents. The amount of H/sub 2/S adsorbed on the silicate, active carbon, and zeolite adsorbents interacted with the heat of adsorption, and among the same kinds of adsorbents, the amount adsorbed was linearly related to the heat of adsorption.

  10. Investigation on the production of hydrogen rich gas in a plasma converter for motorcycle applications

    International Nuclear Information System (INIS)

    Horng, R.-F.; Chang, Y.-P.; Wu, S.-C.

    2006-01-01

    A plasma fuel converter producing a hydrogen rich gas fuel has been designed and constructed. The methodology included using a high voltage electric arc generator to ionize the mixture of methane fuel and air, which was then reformed into a hydrogen rich gas. It transpired from the experiment that the higher the arc frequency, the higher was the generated hydrogen concentration, with a maximum concentration of 43 vol.% attained with an arc frequency of 200 Hz and an O/C (O 2 /CH 4 ) ratio of 0.10. The maximum hydrogen yield of 0.55 was obtained with an arc frequency of 200 Hz and an O/C ratio between 0.20 and 0.25. By fueling a four stroke motorcycle engine with the hydrogen rich gas, low emissions during the cold start idle condition can be obtained

  11. FIRST OPERATING RESULTS OF A DYNAMIC GAS BEARING TURBINE IN AN INDUSTRIAL HYDROGEN LIQUEFIER

    International Nuclear Information System (INIS)

    Bischoff, S.; Decker, L.

    2010-01-01

    Hydrogen has been brought into focus of industry and public since fossil fuels are depleting and costs are increasing dramatically. Beside these issues new high-tech processes in the industry are in need for hydrogen at ultra pure quality. To achieve these requirements and for efficient transportation, hydrogen is liquefied in industrial plants. Linde Gas has commissioned a new 5.5 TPD Hydrogen liquefier in Leuna, Germany, which has been engineered and supplied by Linde Kryotechnik. One of the four expansion turbines installed in the liquefaction process is equipped with dynamic gas bearings. Several design features and operational characteristics of this application will be discussed. The presentation will include results of efficiency and operational reliability that have been determined from performance tests. The advantages of the Linde dynamic gas bearing turbine for future use in hydrogen liquefaction plants will be shown.

  12. Development of fracture toughness test method for nuclear grade graphite

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C. H.; Lee, J. S.; Cho, H. C.; Kim, D. J.; Lee, D. J. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2006-02-15

    Because of its high strength and stability at very high temperature, as well as very low thermal neutron absorption cross-section, graphite has been widely used as a structural material in Gas Cooled Reactors (GCR). Recently, many countries are developing the Very High Temperature gas cooled Reactor (VHTR) because of the potentials of hydrogen production, as well as its safety and viable economics. In VHTR, helium gas serves as the primary coolant. Graphite will be used as a reflector, moderator and core structural materials. The life time of graphite is determined from dimensional changes due to neutron irradiation, which closely relates to the changes of crystal structure. The changes of both lattice parameter and crystallite size can be easily measured by X-ray diffraction method. However, due to high cost and long time of neutron irradiation test, ion irradiation test is being performed instead in KAERI. Therefore, it is essential to develop the technique for measurement of ion irradiation damage of nuclear graphite. Fracture toughness of nuclear grade graphite is one of the key properties in the design and development of VHTR. It is important not only to evaluate the various properties of candidate graphite but also to assess the integrity of nuclear grade graphite during operation. Although fracture toughness tests on graphite have been performed in many laboratories, there have been wide variations in values of the calculated fracture toughness, due to the differences in the geometry of specimens and test conditions. Hence, standard test method for nuclear graphite is required to obtain the reliable fracture toughness values. Crack growth behavior of nuclear grade graphite shows rising R-curve which means the increase in crack growth resistance as the crack length increases. Crack bridging and microcracking have been proposed to be the dominant mechanisms of rising R-curve behavior. In this paper, the technique to measure the changes of crystallite size and

  13. Hydrogen Gas from Serpentinite, Ophiolites and the Modern Ocean Floor as a Source of Green Energy

    Science.gov (United States)

    Coveney, R. M.

    2008-12-01

    Hydrogen gas is emitted by springs associated with serpentinites and extensive carbonate deposits in Oman, The Philippines, the USA and other continental locations. The hydrogen springs contain unusually alkaline fluids with pH values between 11 and 12.5. Other workers have described off-ridge submarine springs with comparably alkaline fluid compositions, serpentinite, abundant free hydrogen gas, and associated carbonate edifices such as Lost City on the Atlantis Massif 15 km west of the Mid-Atlantic Ridge (D.S. Kelley and associates, Science 2005). The association of hydrogen gas with ultramafites is a consistent one that has been attributed to a redox couple involving oxidation of divalent iron to the trivalent state during serpentinization, although other possibilities exist. Some of the hydrogen springs on land are widespread. For example in Oman dozens of alkaline springs (Neal and Stanger, EPSL 1983) can be found over thousands of sq km of outcropping ophiolite. While the deposits in Oman and the Philippines are well-known to much of the geochemical community, little interest seems to have been displayed toward either the ophiolitic occurrences or the submarine deposits for energy production. This may be a mistake as the showings because they could lead to an important source of green energy. Widespread skepticism currently exists about hydrogen as a primary energy source. It is commonly said that free hydrogen does not occur on earth and that it is therefore necessary to use other sources of energy to produce hydrogen, obviating the general environmental benefit. However the existence of numerous occurrences of hydrogen gas associated with ophiolites and submarine occurrences of hydrogen suggests the likelihood that natural hydrogen gas may be an important source of clean energy for modern society remaining to be tapped. Calculations in progress should establish whether or not this is likely to be the case.

  14. Hydrogen Sensors Boost Hybrids; Today's Models Losing Gas?

    Science.gov (United States)

    2005-01-01

    Advanced chemical sensors are used in aeronautic and space applications to provide safety monitoring, emission monitoring, and fire detection. In order to fully do their jobs, these sensors must be able to operate in a range of environments. NASA has developed sensor technologies addressing these needs with the intent of improving safety, optimizing combustion efficiencies, and controlling emissions. On the ground, the chemical sensors were developed by NASA engineers to detect potential hydrogen leaks during Space Shuttle launch operations. The Space Shuttle uses a combination of hydrogen and oxygen as fuel for its main engines. Liquid hydrogen is pumped to the external tank from a storage tank located several hundred feet away. Any hydrogen leak could potentially result in a hydrogen fire, which is invisible to the naked eye. It is important to detect the presence of a hydrogen fire in order to prevent a major accident. In the air, the same hydrogen-leak dangers are present. Stress and temperature changes can cause tiny cracks or holes to form in the tubes that line the Space Shuttle s main engine nozzle. Such defects could allow the hydrogen that is pumped through the nozzle during firing to escape. Responding to the challenges associated with pinpointing hydrogen leaks, NASA endeavored to improve propellant leak-detection capabilities during assembly, pre-launch operations, and flight. The objective was to reduce the operational cost of assembling and maintaining hydrogen delivery systems with automated detection systems. In particular, efforts have been focused on developing an automated hydrogen leak-detection system using multiple, networked hydrogen sensors that are operable in harsh conditions.

  15. A pyrolysis/gas chromatographic method for the determination of hydrogen in solid samples

    Science.gov (United States)

    Carr, R. H.; Bustin, R.; Gibson, E. K.

    1987-01-01

    A method is described for the determination of hydrogen in solid samples. The sample is heated under vacuum after which the evolved gases are separated by gas chromatography with a helium ionization detector. The system is calibrated by injecting known amounts of hydrogen, as determined manometrically. The method, which is rapid and reliable, was checked for a variety of lunar soils; the limit of detection is about 10 ng of hydrogen.

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

    Science.gov (United States)

    2015-07-01

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

  17. Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

    KAUST Repository

    Logan, Bruce E.; Call, Douglas; Cheng, Shaoan; Hamelers, Hubertus V. M.; Sleutels, Tom H. J. A.; Jeremiasse, Adriaan W.; Rozendal, René A.

    2008-01-01

    production rates. MECs used to make hydrogen gas are similar in design to microbial fuel cells (MFCs) that produce electricity, but there are important differences in architecture and analytical methods used to evaluate performance. We review here

  18. Hydrogen extraction from liquid lithium-lead alloy by gas-liquid contact method

    International Nuclear Information System (INIS)

    Xie Bo; Weng Kuiping; Hou Jianping; Yang Guangling; Zeng Jun

    2013-01-01

    Hydrogen extraction experiment from liquid lithium-lead alloy by gas-liquid contact method has been carried out in own liquid lithium-lead bubbler (LLLB). Experimental results show that, He is more suitable than Ar as carrier gas in the filler tower. The higher temperature the tower is, the greater hydrogen content the tower exports. Influence of carrier gas flow rate on the hydrogen content in the export is jagged, no obvious rule. Although the difference between experimental results and literature data, but it is feasible that hydrogen isotopes extraction experiment from liquid lithium-lead by gas-liquid contact method, and the higher extraction efficiency increases with the growth of the residence time of the alloy in tower. (authors)

  19. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: BIOQUELL, INC. CLARIS C HYDROGEN PEROXIDE GAS GENERATOR

    Science.gov (United States)

    The Environmental Technology Verification report discusses the technology and performance of the Clarus C Hydrogen Peroxide Gas Generator, a biological decontamination device manufactured by BIOQUELL, Inc. The unit was tested by evaluating its ability to decontaminate seven types...

  20. Inspection of the hydrogen gas pressure with metal shield by cold neutron radiography at CMRR

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hang; Cao, Chao; Huo, Heyong; Wang, Sheng; Wu, Yang; Yin, Wei; Sun, Yong; Liu, Bin; Tang, Bin [Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang (China); Key Laboratory of Neutron Physics, Chinese Academy of Engineering Physics, Mianyang (China)

    2017-04-11

    The inspection of the process of gas pressure change is important for some applications (e.g. gas tank stockpile or two phase fluid model) which need quantitative and non-touchable measurement. Neutron radiography provides a suitable tool for such investigations with nice resolution. The quantitative cold neutron radiography (CNR) is developed at China Mianyang Research Reactor (CMRR) to measure the hydrogen gas pressure with metal shield. Because of the high sensitivity to hydrogen, even small change of the hydrogen pressure can be inspected by CNR. The dark background and scattering neutron effect are both corrected to promote measurement precision. The results show that CNR can measure the hydrogen gas pressure exactly and the pressure value average relative error between CNR and barometer is almost 1.9%.

  1. Performance of a hydrogen/deuterium polarized gas target in a storage ring

    NARCIS (Netherlands)

    van Buuren, L.D.; Szczerba, D.; van den Brand, J.F.J.; Bulten, H.J.; Klous, S.; Mul, F.A.; Poolman, H.R.; Simani, M.C.

    2001-01-01

    The performance of a hydrogen/deuterium polarized gas target in a storage ring is presented. The target setup consisted of an atomic beam source, a cryogenic storage cell and a Breit-Rabi polarimeter. High frequency transition units were constructed to produce vector polarized hydrogen and

  2. Catalysis by Single Atoms: Water Gas Shift and Ethylene Hydrogenation

    Science.gov (United States)

    2009-04-20

    addition to other microscopic phenomena at region of coefficients . Silicon carbide has a higher loss tangent at 2.4 GHz than most ceramics, and thus...Si 50 35 30 20 Ni 50 — — D. Sample holder and preparation: * The remainder is ZrB2. Graphite sheet ( McMaster -Carr, USA) is cut into different...results. 19 B. Microwave hybrid processing i. Microwave heating: 1. Volumetric Microwave absorption is proportional to the loss

  3. Study of Catalyst Variation Effect in Glycerol Conversion Process to Hydrogen Gas by Steam Reforming

    Science.gov (United States)

    Widayat; Hartono, R.; Elizabeth, E.; Annisa, A. N.

    2018-04-01

    Along with the economic development, needs of energy being increase too. Hydrogen as alternative energy has many usages. Besides that, hydrogen is one source of energy that is a clean fuel, but process production of hydrogen from natural gas as a raw material has been used for a long time. Therefore, there is need new invention to produce hydrogen from the others raw material. Glycerol, a byproduct of biodiesel production, is a compound which can be used as a raw material for hydrogen production. By using glycerol as a raw material of hydrogen production, we can get added value of glycerol as well as an energy source solution. The process production of hydrogen by steam reforming is a thermochemical process with efficiency 70%. This process needs contribution of catalyst to improve its efficiency and selectivity of the process. In this study will be examined the effect variation of catalyst for glycerol conversion process to hydrogen by steam reforming. The method for catalyst preparation was variation of catalyst impregnation composition, catalyst calcined with difference concentration of hydrochloric acid and calcined with difference hydrochloric acid ratio. After that, all of catalyst which have been prepared, used for steam reforming process for hydrogen production from glycerol as a raw material. From the study, the highest yield of hydrogen gas showed in the process production by natural zeolite catalyst with 1:15 Hydrochloric acid ratio was 42.28%. Hydrogen yield for 2M calcined natural zeolite catalyst was 38.37%, for ZSM-5 catalyst was 15.83%, for 0.5M calcined natural zeolite was 13.09% and for ultrasonic natural zeolite was 11.43%. The lowest yield of hydrogen gas showed in catalyst 2Zn/ZSM-5 with 11.22%. This result showed that hydrogen yield product was affected by catalyst variation because of the catalyst has difference characteristic and difference catalytic activity after the catalyst preparation process.

  4. Generation of oxy-hydrogen gas and its effect on performance of spark ignition engine

    Science.gov (United States)

    Patil, N. N.; Chavan, C. B.; More, A. S.; Baskar, P.

    2017-11-01

    Considering the current scenario of petroleum fuels, it has been observed that, they will last for few years from now. On the other hand, the ever increasing cost of a gasoline fuels and their related adverse effects on environment caught the attention of researchers to find a supplementary source. For commercial fuels, supplementary source is not about replacing the entire fuel, instead enhancing efficiency by simply making use of it in lesser amount. From the recent research that has been carried out, focus on the use of Hydrogen rich gas as a supplementary source of fuel has increased. But the problem related to the storage of hydrogen gas confines the application of pure hydrogen in petrol engine. Using oxy-hydrogen gas (HHO) generator the difficulties of storing the hydrogen have overcome up to a certain limit. The present study highlights on performance evaluation of conventional petrol engine by using HHO gas as a supplementary fuel. HHO gas was generated from the electrolysis of water. KOH solution of 3 Molar concentration was used which act as a catalyst and accelerates the rate of generation of HHO gas. Quantity of gas to be supplied to the engine was controlled by varying amount of current. It was observed that, engine performance was improved on the introduction of HHO gas.

  5. Application of CFRP with High Hydrogen Gas Barrier Characteristics to Fuel Tanks of Space Transportation System

    Science.gov (United States)

    Yonemoto, Koichi; Yamamoto, Yuta; Okuyama, Keiichi; Ebina, Takeo

    In the future, carbon fiber reinforced plastics (CFRPs) with high hydrogen gas barrier performance will find wide applications in all industrial hydrogen tanks that aim at weight reduction; the use of such materials will be preferred to the use of conventional metallic materials such as stainless steel or aluminum. The hydrogen gas barrier performance of CFRP will become an important issue with the introduction of hydrogen-fuel aircraft. It will also play an important role in realizing fully reusable space transportation system that will have high specific tensile CFRP structures. Such materials are also required for the manufacture of high-pressure hydrogen gas vessels for use in the fuel cell systems of automobiles. This paper introduces a new composite concept that can be used to realize CFRPs with high hydrogen gas barrier performance for applications in the cryogenic tanks of fully reusable space transportation system by the incorporation of a nonmetallic crystal layer, which is actually a dense and highly oriented clay crystal laminate. The preliminary test results show that the hydrogen gas barrier characteristics of this material after cryogenic heat shocks and cyclic loads are still better than those of other polymer materials by approximately two orders of magnitude.

  6. Tables of formulae for calculating the mechanics of stacks in gas-graphite reactors; Formulaire pour le calcul de la mecanique des empilements des reacteurs graphite-gaz

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1968-07-01

    This collection of formulae only gives, for nuclear graphite stacks. The mechanical effects due to the strains, thermal or not, of steel structures supporting or surrounding graphite blocks. Equations have been established by mean of experiments made at Chinon with large pile models. Thus, it is possible to calculate displacement, strain and stress in the EDF type stacks of horizontal triangular block lattice. (authors) [French] Le domaine de ce formulaire est strictement limite aux effets mecaniques, pour les empilements, des deformations, thermiques ou autres, des structures metalliques de soutien (aire - support et corset). On propose un ensemble de relations qui ont ete etablies a la suite des essais de CHINON sur des maquettes de grande taille. Ces relations permettent le calcul des mouvements, des deformations et des contraintes dans les empilements du type EDF, a reseau horizontal triangulaire regulier. (auteurs)

  7. Production of dissociated hydrogen gas by electro-magnetically driven shock

    International Nuclear Information System (INIS)

    Kondo, Kotaro; Moriyama, Takao; Hasegawa, Jun; Horioka, Kazuhiko; Oguri, Yoshiyuki

    2013-01-01

    Evaluation of ion stopping power which has a dependence on target temperature and density is an essential issue for heavy-ion-driven high energy density experiment. We focus on experimentally unknown dissociated hydrogen atoms as target for stopping power measurement. The precise measurement of shock wave velocity is required because the dissociated gas is produced by electro-magnetically driven shock. For beam-dissociated hydrogen gas interaction experiment, shock velocity measurement using laser refraction is proposed. (author)

  8. Applications of ion implantation for modifying the interactions between metals and hydrogen gas

    Science.gov (United States)

    Musket, R. G.

    1989-04-01

    Ion implantations into metals have been shown recently to either reduce or enhance interactions with gaseous hydrogen. Published studies concerned with modifications of these interactions are reviewed and discussed in terms of the mechanisms postulated to explain the observed changes. The interactions are hydrogenation, hydrogen permeation, and hydrogen embrittlement. In particular, the results of the reviewed studies are (a) uranium hydriding suppressed by implantation of oxygen and carbon, (b) hydrogen gettered in iron and nickel using implantation of titanium, (c) hydriding of titanium catalyzed by implanted palladium, (d) tritium permeation of 304L stainless steel reduced using selective oxidation of implanted aluminum, and (e) hydrogen attack of a low-alloy steel accelerated by implantation of helium. These studies revealed ion implantation to be an effective method for modifying the interactions of hydrogen gas with metals.

  9. Applications of ion implantation for modifying the interactions between metals and hydrogen gas

    International Nuclear Information System (INIS)

    Musket, R.G.

    1989-01-01

    Ion implantations into metals have been shown recently to either reduce or enhance interactions with gaseous hydrogen. Published studies concerned with modifications of these interactions are reviewed and discussed in terms of the mechanisms postulated to explain the observed changes. The interactions are hydrogenation, hydrogen permeation and hydrogen embrittlement. In particular, the results of the reviewed studies are 1. uranium hydriding suppressed by implantation of oxygen and carbon, 2. hydrogen gettered in iron and nickel using implantation of titanium, 3. hydriding of titanium catalyzed by implanted palladium, 4. tritium permeation of 304L stainless steel reduced using selective oxidation of implanted aluminum, and 5. hydrogen attack of a low-alloy steel accelerated by implantation of helium. These studies revealed ion implantation to be an effective method for modifying the interactions of hydrogen gas with metals. (orig.)

  10. Rhodium nanoparticle-modified screen-printed graphite electrodes for the determination of hydrogen peroxide in tea extracts in the presence of oxygen.

    Science.gov (United States)

    Gatselou, Vasiliki A; Giokas, Dimothenis L; Vlessidis, Athanasios G; Prodromidis, Mamas I

    2015-03-01

    In this work we describe the fabrication of nanostructured electrocatalytic surfaces based on polyethyleneimine (PEI)-supported rhodium nanoparticles (Rh-NP) over graphite screen-printed electrodes (SPEs) for the determination of hydrogen peroxide in the presence of oxygen. Rh-NP, electrostatically stabilized by citrate anions, were immobilized over graphite SPEs, through coulombic attraction on a thin film of positively charged PEI. The functionalized sensors, polarized at 0.0 V vs. Ag/AgCl/3 M KCl, exhibited a linear response to H2O2 over the concentration range from 5 to 600 μmol L(-1) H2O2 in the presence of oxygen. The 3σ limit of detection was 2 μmol L(-1) H2O2, while the reproducibility of the method at the concentration level of 10 μmol L(-1) H2O2 (n=10) and between different sensors (n=4) was lower than 3 and 5%, respectively. Most importantly, the sensors showed an excellent working and storage stability at ambient conditions and they were successfully applied to the determination of H2O2 produced by autooxidation of polylphenols in tea extracts with ageing. Recovery rates ranged between 97 and 104% suggesting that the as-prepared electrodes can be used for the development of small-scale, low-cost chemical sensors for use in on-site applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Screen-Printed Graphite Electrodes as Low-Cost Devices for Oxygen Gas Detection in Room-Temperature Ionic Liquids.

    Science.gov (United States)

    Lee, Junqiao; Hussain, Ghulam; Banks, Craig E; Silvester, Debbie S

    2017-11-26

    Screen-printed graphite electrodes (SPGEs) have been used for the first time as platforms to detect oxygen gas in room-temperature ionic liquids (RTILs). Up until now, carbon-based SPEs have shown inferior behaviour compared to platinum and gold SPEs for gas sensing with RTIL solvents. The electrochemical reduction of oxygen (O₂) in a range of RTILs has therefore been explored on home-made SPGEs, and is compared to the behaviour on commercially-available carbon SPEs (C-SPEs). Six common RTILs are initially employed for O₂ detection using cyclic voltammetry (CV), and two RTILs ([C₂mim][NTf₂] and [C₄mim][PF₆]) chosen for further detailed analytical studies. Long-term chronoamperometry (LTCA) was also performed to test the ability of the sensor surface for real-time gas monitoring. Both CV and LTCA gave linear calibration graphs-for CV in the 10-100% vol. range, and for LTCA in the 0.1-20% vol. range-on the SPGE. The responses on the SPGE were far superior to the commercial C-SPEs; more instability in the electrochemical responses were observed on the C-SPEs, together with some breaking-up or dissolution of the electrode surface materials. This study highlights that not all screen-printed ink formulations are compatible with RTIL solvents for longer-term electrochemical experiments, and that the choice of RTIL is also important. Overall, the low-cost SPGEs appear to be promising platforms for the detection of O₂, particularly in [C₄mim][PF₆].

  12. Screen-Printed Graphite Electrodes as Low-Cost Devices for Oxygen Gas Detection in Room-Temperature Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Junqiao Lee

    2017-11-01

    Full Text Available Screen-printed graphite electrodes (SPGEs have been used for the first time as platforms to detect oxygen gas in room-temperature ionic liquids (RTILs. Up until now, carbon-based SPEs have shown inferior behaviour compared to platinum and gold SPEs for gas sensing with RTIL solvents. The electrochemical reduction of oxygen (O2 in a range of RTILs has therefore been explored on home-made SPGEs, and is compared to the behaviour on commercially-available carbon SPEs (C-SPEs. Six common RTILs are initially employed for O2 detection using cyclic voltammetry (CV, and two RTILs ([C2mim][NTf2] and [C4mim][PF6] chosen for further detailed analytical studies. Long-term chronoamperometry (LTCA was also performed to test the ability of the sensor surface for real-time gas monitoring. Both CV and LTCA gave linear calibration graphs—for CV in the 10–100% vol. range, and for LTCA in the 0.1–20% vol. range—on the SPGE. The responses on the SPGE were far superior to the commercial C-SPEs; more instability in the electrochemical responses were observed on the C-SPEs, together with some breaking-up or dissolution of the electrode surface materials. This study highlights that not all screen-printed ink formulations are compatible with RTIL solvents for longer-term electrochemical experiments, and that the choice of RTIL is also important. Overall, the low-cost SPGEs appear to be promising platforms for the detection of O2, particularly in [C4mim][PF6].

  13. Construction and performance testing of a secondary cooling system with hydrogen gas (I)

    International Nuclear Information System (INIS)

    Hishida, M.; Nekoya, S.; Takizuka, T.; Emori, K.; Ogawa, M.; Ouchi, M.; Okamoto, Y.; Sanokawa, K.; Nakano, T.; Hagiwara, T.

    1979-08-01

    An experimental multi-purpose High-Temperature Gas Cooled Reactor (VHTR) which is supposed to be used for a direct steel-making is now being developed in JAeRI. In order to simulate the heat exchanging system between the primary helium gas and the secondary reducing gas system of VHTR, a hydrogen gas loop was constructed as a secondary cooling system of the helium gas loop. The maximum temperature and the maximum pressure of the hydrogen gas are 900 degrees C and 42 kg/cm 2 x G respectively. The construction of the hydrogen gas loop was completed in January, 1977, and was successfully operated for 1.000 h. Various performance tests, such as the hydrogen permeation test of a He/H2 heat exchanger and the thermal performance test of heat exchangers, were made. Especially, it was proved that hydrogen permeation rate through the heat exchanger was reduced to 1/30 to approximately 1/50 by a method of calorized coating, and the coating was stable during 1.000 h's operation. It was also stable against the temperature changes. This report describes the outline of the facility and performance of the components. (orig.) [de

  14. Effects of hydrogen mixture into helium gas on deuterium removal from lithium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Akihito, E-mail: tsuchiya@frontier.hokudai.ac.jp [Laboratory of Plasma Physics and Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Hino, Tomoaki; Yamauchi, Yuji; Nobuta, Yuji [Laboratory of Plasma Physics and Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Akiba, Masato; Enoeda, Mikio [Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193 (Japan)

    2013-10-15

    Lithium titanate (Li{sub 2}TiO{sub 3}) pebbles were irradiated with deuterium ions with energy of 1.7 keV and then exposed to helium or helium–hydrogen mixed gas at various temperatures, in order to evaluate the effects of gas exposure on deuterium removal from the pebbles. The amounts of residual deuterium in the pebbles were measured by thermal desorption spectroscopy. The mixing of hydrogen gas into helium gas enhanced the removal amount of deuterium. In other words, the amount of residual deuterium after the helium–hydrogen mixed gas exposure at lower temperature was lower than that after the helium gas exposure. In addition, we also evaluated the pebbles exposed to the helium gas with different hydrogen mixture ratio from 0% to 1%, at 573 K. Although the amount of residual deuterium in the pebbles after the exposure decreased with increasing the hydrogen mixture ratio, the implanted deuterium partly remained after the exposure. These results suggest that the tritium inventory may occur at low temperature region in the blanket during the operation.

  15. Unique Fe2P Nanoparticles Enveloped in Sandwichlike Graphited Carbon Sheets as Excellent Hydrogen Evolution Reaction Catalyst and Lithium-Ion Battery Anode.

    Science.gov (United States)

    Zhang, Yan; Zhang, Huijuan; Feng, Yangyang; Liu, Li; Wang, Yu

    2015-12-09

    The novel Fe2P nanoparticles encapsulated in sandwichlike graphited carbon envelope nanocomposite (Fe2P/GCS) that can be first applied in hydrogen evolution reaction (HER) as well as lithium-ion batteries (LIBs) has been designed and fabricated. The unique sandwiched Fe2P/GCS is characterized with several prominent merits, including large specific surface area, nanoporous structure, excellent electronic conductivity, enhanced structural integrity and so on. All of these endow the Fe2P/GCS with brilliant electrochemical performance. When used as a HER electrocatalyst in acidic media, the harvested Fe2P/GCS demonstrates low onset overpotential and Tafel slope as well as particularly outstanding durability. Moreover, as an anode material for LIBs, the sandwiched Fe2P/GCS presents high specific capacity and excellent cyclability and rate capability. As a consequence, the acquired Fe2P/GCS is a promising material for energy applications, especially HER and LIBs.

  16. Hysec Process: production of high-purity hydrogen from coke oven gas

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, S

    1984-01-01

    An account is given of the development of the Hysec Process by the Kansai Netsukagaku and Mitsubishi Kakoki companies. The process is outlined and its special features noted. The initial development aim was to obtain high-purity hydrogen from coke oven gas by means of PSA. To achieve this, ways had to be found for removing the impurities in the coke oven gas and the trace amounts of oxygen which are found in the product hydrogen. The resulting hydrogen is 99.9999% pure. 3 references.

  17. The self limiting effect of hydrogen cluster in gas jet under liquid nitrogen temperature

    International Nuclear Information System (INIS)

    Han Jifeng; Yang Chaowen; Miao Jingwei; Fu Pengtao; Luo Xiaobing; Shi Miangong

    2010-01-01

    The generation of hydrogen clusters in gas jet is tested using the Rayleigh scattering method under liquid nitrogen temperature of 79 K. The self limiting effect of hydrogen cluster is studied and it is found that the cluster formation is greatly affected by the number of expanded molecules. The well designed liquid nitrogen cold trap ensured that the hydrogen cluster would keep maximum size for maximum 15 ms during one gas jet. The scattered light intensity exhibits a power scaling on the backing pressure ranging from 5 to 48 bar with the power value of 4.1.

  18. Empirical Method to Estimate Hydrogen Embrittlement of Metals as a Function of Hydrogen Gas Pressure at Constant Temperature

    Science.gov (United States)

    Lee, Jonathan A.

    2010-01-01

    High pressure Hydrogen (H) gas has been known to have a deleterious effect on the mechanical properties of certain metals, particularly, the notched tensile strength, fracture toughness and ductility. The ratio of these properties in Hydrogen as compared to Helium or Air is called the Hydrogen Environment Embrittlement (HEE) Index, which is a useful method to classify the severity of H embrittlement and to aid in the material screening and selection for safety usage H gas environment. A comprehensive world-wide database compilation, in the past 50 years, has shown that the HEE index is mostly collected at two conveniently high H pressure points of 5 ksi and 10 ksi near room temperature. Since H embrittlement is directly related to pressure, the lack of HEE index at other pressure points has posed a technical problem for the designers to select appropriate materials at a specific H pressure for various applications in aerospace, alternate and renewable energy sectors for an emerging hydrogen economy. Based on the Power-Law mathematical relationship, an empirical method to accurately predict the HEE index, as a function of H pressure at constant temperature, is presented with a brief review on Sievert's law for gas-metal absorption.

  19. Construction and performance tests of a secondary hydrogen gas cooling system

    International Nuclear Information System (INIS)

    Sanokawa, K.; Hishida, M.

    1980-01-01

    With the aim of a multi-purpose use of nuclear energy, such as direct steel-making, an experimental multi-purpose high-temperature gas-cooled reactor (VHTR) is now being developed by the Japan Atomic Energy Research Institute (JAERI). In order to simulate a heat exchanging system between the primary helium gas loop and the secondary reducing gas system of the VHTR, a hydrogen gas loop as a secondary cooling system of the existing helium gas loop was completed in 1977, and was successfully operated for over 2000 hours. The objectives of constructing the H 2 secondary loop were: (1) To get basic knowledge for designing, constructing and operating a high-temperature and high-pressure gas facility; (2) To perform the following tests: (a) hydrogen permeation at the He/H 2 heat exchanger (the surfaces of the heat exchanger tubes are coated by calorizing to reduce hydrogen permeation), (b) thermal performance tests of the He/H 2 heat exchanger and the H 2 /H 2 regenerative heat exchanger, (c) performance test of internal insulation, and (d) performance tests of the components such as a H 2 gas heater and gas purifiers. These tests were carried out at He gas temperature of approximately 1000 0 C, H 2 gas temperature of approximately 900 0 C and gas pressures of approximately 40 kg/cm 2 G, which are almost the same as the operating conditions of the VHTR

  20. The Influence of Hydrogen Gas on the Measures of Efficiency of Diesel Internal Combustion Engine

    Directory of Open Access Journals (Sweden)

    Jurgis Latakas

    2014-12-01

    Full Text Available In this research paper energy and ecological parameters of diesel engine which works under addition of hydrogen (10, 20, 30 l/ min are presented. A survey of research literature has shown that addition of hydrogen gases improve diesel combustion; increase indicated pressure; decrease concentration of carbon dioxide (CO2, hydrocarbons (HC, particles; decrease fuel consumptions. Results of the experiment revealed that hydrogen gas additive decreased pressure in cylinder in kinetic combustion phase. Concentration of CO2 and nitrous oxides (NOx decreased not significantly, HC – increased. Concentration of particles in engine exhaust gases significantly decreased. In case when hydrogen gas as additive was supplied, the fuel consumptions decreased a little. Using AVL BOOST software combustion process analysis was made. It was determined that in order to optimize engine work process under hydrogen additive usage, it is necessary to adjust diesel injection angle.

  1. Hydrogen.

    Science.gov (United States)

    Bockris, John O'M

    2011-11-30

    The idea of a "Hydrogen Economy" is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO₂ in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H₂ from the electrolyzer. Methanol made with CO₂ from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  2. Hydrate dissociation conditions for gas mixtures containing carbon dioxide, hydrogen, hydrogen sulfide, nitrogen, and hydrocarbons using SAFT

    International Nuclear Information System (INIS)

    Li Xiaosen; Wu Huijie; Li Yigui; Feng Ziping; Tang Liangguang; Fan Shuanshi

    2007-01-01

    A new method, a molecular thermodynamic model based on statistical mechanics, is employed to predict the hydrate dissociation conditions for binary gas mixtures with carbon dioxide, hydrogen, hydrogen sulfide, nitrogen, and hydrocarbons in the presence of aqueous solutions. The statistical associating fluid theory (SAFT) equation of state is employed to characterize the vapor and liquid phases and the statistical model of van der Waals and Platteeuw for the hydrate phase. The predictions of the proposed model were found to be in satisfactory to excellent agreement with the experimental data

  3. Role of sodium hydroxide in the production of hydrogen gas from the hydrothermal gasification of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Onwudili, Jude A.; Williams, Paul T. [Energy and Resources Research Institute, University of Leeds, Leeds, LS2 9JT (United Kingdom)

    2009-07-15

    The role of sodium hydroxide as a promoter of hydrogen gas production during the hydrothermal gasification of glucose and other biomass samples has been investigated. Experiments were carried out in a batch reactor with glucose and also in the presence of the alkali from 200 C, 2 MPa to 450 C, 34 MPa at constant water loading. Without sodium hydroxide, glucose decomposed to produce mainly carbon dioxide, water, char and tar. Furfural, its derivatives and reaction products dominated the ethyl acetate extract of the water (organic fraction) at lower reaction conditions. This indicated that the dehydration of glucose to yield these products was unfavourable to hydrogen gas production. In the presence of sodium hydroxide however, glucose initially decomposed to form mostly alkylated and hydroxylated carbonyl compounds, whose further decomposition yielded hydrogen gas. It was observed that at 350 C, 21.5 MPa, half of the optimum hydrogen gas yield had formed and at 450 C, 34 MPa, more than 80 volume percent of the gaseous effluent was hydrogen gas, while the balance was hydrocarbon gases, mostly methane ({>=}10 volume percent). Other biomass samples were also comparably reacted at the optimum conditions observed for glucose. The rate of hydrogen production for the biomass samples was in the following order; glucose > cellulose, starch, rice straw > potato > rice husk. (author)

  4. Gas-phase hydrogenation of benzene on supported nickel catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Franco, H.A.; Phillips, M.J.

    1980-06-01

    The reaction of 22.66-280 Pa benzene with 72.39-122.79 Pa hydrogen on kieselguhr-supported nickel at 392.2/sup 0/-468.2/sup 0/K yielded only cyclohexane and was independent of 5.33-40 Pa cyclohexane added to the feed of the differential flow reactor. Best fit for the kinetic data was obtained with a rate equation developed by van Meerten and Coenen which assumed that all hydrogen addition steps have the same rate constant and are slow. An observed rate maximum at 458/sup 0/K may be the result of an increasing rate constant and decreasing cyclohexyl surface coverage as the temperature increases. Temperature-programed hydrogen desorption showed a series of desorption peaks at 358/sup 0/-600/sup 0/K, including one at 453/sup 0/K, which may be due to the hydrogen involved in the surface reaction.

  5. Development and industrial application of catalyzer for low-temperature hydrogenation hydrolysis of Claus tail gas

    Directory of Open Access Journals (Sweden)

    Honggang Chang

    2015-10-01

    Full Text Available With the implementation of more strict national environmental protection laws, energy conservation, emission reduction and clean production will present higher requirements for sulfur recovery tail gas processing techniques and catalyzers. As for Claus tail gas, conventional hydrogenation catalyzers are gradually being replaced by low-temperature hydrogenation catalyzers. This paper concentrates on the development of technologies for low-temperature hydrogenation hydrolysis catalyzers, preparation of such catalyzers and their industrial application. In view of the specific features of SO2 hydrogenation and organic sulfur hydrolysis during low-temperature hydrogenation, a new technical process involving joint application of hydrogenation catalyzers and hydrolysis catalyzers was proposed. In addition, low-temperature hydrogenation catalyzers and low-temperature hydrolysis catalyzers suitable for low-temperature conditions were developed. Joint application of these two kinds of catalyzers may reduce the inlet temperatures in the conventional hydrogenation reactors from 280 °C to 220 °C, at the same time, hydrogenation conversion rates of SO2 can be enhanced to over 99%. To further accelerate the hydrolysis rate of organic sulfur, the catalyzers for hydrolysis of low-temperature organic sulfur were developed. In lab tests, the volume ratio of the total sulfur content in tail gas can be as low as 131 × 10−6 when these two kinds of catalyzers were used in a proportion of 5:5 in volumes. Industrial application of these catalyzers was implemented in 17 sulfur recovery tail gas processing facilities of 15 companies. As a result, Sinopec Jinling Petrochemical Company had outstanding application performances with a tail gas discharging rate lower than 77.9 mg/m3 and a total sulfur recovery of 99.97%.

  6. Hydrogen gas reduces hyperoxic lung injury via the Nrf2 pathway in vivo

    Science.gov (United States)

    Kawamura, Tomohiro; Wakabayashi, Nobunao; Shigemura, Norihisa; Huang, Chien-Sheng; Masutani, Kosuke; Tanaka, Yugo; Noda, Kentaro; Peng, Ximei; Takahashi, Toru; Billiar, Timothy R.; Okumura, Meinoshin; Toyoda, Yoshiya; Kensler, Thomas W.

    2013-01-01

    Hyperoxic lung injury is a major concern in critically ill patients who receive high concentrations of oxygen to treat lung diseases. Successful abrogation of hyperoxic lung injury would have a huge impact on respiratory and critical care medicine. Hydrogen can be administered as a therapeutic medical gas. We recently demonstrated that inhaled hydrogen reduced transplant-induced lung injury and induced heme oxygenase (HO)-1. To determine whether hydrogen could reduce hyperoxic lung injury and investigate the underlying mechanisms, we randomly assigned rats to four experimental groups and administered the following gas mixtures for 60 h: 98% oxygen (hyperoxia), 2% nitrogen; 98% oxygen (hyperoxia), 2% hydrogen; 98% balanced air (normoxia), 2% nitrogen; and 98% balanced air (normoxia), 2% hydrogen. We examined lung function by blood gas analysis, extent of lung injury, and expression of HO-1. We also investigated the role of NF-E2-related factor (Nrf) 2, which regulates HO-1 expression, by examining the expression of Nrf2-dependent genes and the ability of hydrogen to reduce hyperoxic lung injury in Nrf2-deficient mice. Hydrogen treatment during exposure to hyperoxia significantly improved blood oxygenation, reduced inflammatory events, and induced HO-1 expression. Hydrogen did not mitigate hyperoxic lung injury or induce HO-1 in Nrf2-deficient mice. These findings indicate that hydrogen gas can ameliorate hyperoxic lung injury through induction of Nrf2-dependent genes, such as HO-1. The findings suggest a potentially novel and applicable solution to hyperoxic lung injury and provide new insight into the molecular mechanisms and actions of hydrogen. PMID:23475767

  7. A pore structure model for the gas transport property changes, initial oxidation rates and cumulative weight loss of AGR moderator graphite

    International Nuclear Information System (INIS)

    Johnson, P.A.V.

    1985-09-01

    A quantitative model has been developed for the gas transport property variation, cumulative weight loss and initial oxidation rates of AGR moderator graphite. The model utilises the theory of dynamic moments of the pore structure to calculate the changes in physical properties brought about by radiolytic corrosion taking place within the graphite porosity. In order to account for the behaviour of the initial rate curves, and the weight loss data obtained it is necessary to invoke the presence of a group of cylindrical pore and a group of small slab-shaped pores. The latter are methane depleted. This is in addition to the pore group involved in gas transport which is best represented by cylinders of mean radius 2.13 μm. The model satisfactorily predicts the experimental weight loss data obtained from experiments in the DIDO 6V3 and BFB loops. (author)

  8. Influence of fillers on hydrogen penetration properties and blister fracture of rubber composites for O-ring exposed to high-pressure hydrogen gas

    Energy Technology Data Exchange (ETDEWEB)

    Yamabe, Junichiro; Nishimura, Shin [Department of Mechanical Science Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Research Center for Hydrogen Industrial Use and Storage (HYDROGENIUS), National Institute of Advanced Industrial Science and Technology (AIST), 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

    2009-02-15

    Ethylene-propylene rubber (EPDM) and nitrile-butadiene rubber (NBR) composites having carbon black, silica, and no fillers were exposed to hydrogen gas at a maximum pressure of 10 MPa; then, blister tests and the measurement of hydrogen content were conducted. The hydrogen contents of the composites were proportional to the hydrogen pressure, i.e., the behavior of their hydrogen contents follows Henry's law. This implies that hydrogen penetrates into the composite as a hydrogen molecule. The addition of carbon black raised the hydrogen content of the composite, while the addition of silica did not. Based on observations, the blister damages of composites with silica were less pronounced, irrespective of the hydrogen pressures. This may be attributed to their lower hydrogen content and relatively better tensile properties than the others. (author)

  9. Geochemical modelling of hydrogen gas migration in an unsaturated bentonite buffer

    NARCIS (Netherlands)

    Sedighi, M.; Thomas, H.R.; Al Masum, S.; Vardon, P.J.; Nicholson, D.; Chen, Q.

    2014-01-01

    This paper presents an investigation of the transport and fate of hydrogen gas through compacted bentonite buffer. Various geochemical reactions that may occur in the multiphase and multicomponent system of the unsaturated bentonite buffer are considered. A reactive gas transport model, developed

  10. Gas phase hydrogen peroxide production in atmospheric pressure glow discharges operating in He - H2O

    NARCIS (Netherlands)

    Vasko, C.A.; Veldhuizen, van E.M.; Bruggeman, P.J.

    2013-01-01

    The gas phase production of hydrogen peroxide (H2O2) in a RF atmospheric pressure glow discharge with helium and water vapour has been investigated as a function of the gas flow. It is shown that the production of H2O2 is through the recombination of two OH radicals in a three body collision and the

  11. Antibody-integrated and functionalized graphite-encapsulated magnetic beads, produced using ammonia gas plasma technology, for capturing Salmonella.

    Science.gov (United States)

    Sakudo, Akikazu; Chou, Han; Nagatsu, Masaaki

    2015-03-01

    Salmonella spp. is the single and most important causative agent of foodborne infections, especially involving foods such as eggs, milk and meat. To prevent infection, a reliable surveillance system is required that can quickly and sensitively detect Salmonella. Here, we describe the development of antibody-integrated magnetic beads that are functionalized by a novel strategy using ammonia gas plasma. Ammonia plasma, produced by a radio frequency (RF) power supply, was allowed to react with the surface of graphite-encapsulated magnetic beads, resulting in the introduction of amino groups. An anti-Salmonella antibody was then anchored by sulfide groups present on the protein surface to the amino groups of the magnetic beads via N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP). The potential usefulness of these magnetic beads for capturing Salmonella was examined as follows. The beads were incubated with Salmonella in liquid medium and then separated from the supernatant by applying a magnetic field. After thorough washing, adsorption of Salmonella to the beads was confirmed by immunochromatography, polymerase chain reaction and a direct culture assay. Our findings indicate that the capture and concentration of Salmonella using the antibody-integrated magnetic beads was more efficient than commercial Dynabeads® anti-Salmonella, which are conventionally used for concentrating Salmonella from liquid cultures. We believe this novel bead technology will contribute to the enhanced detection of Salmonella. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Hydrogen generation from natural gas for the fuel cell systems of tomorrow

    Science.gov (United States)

    Dicks, Andrew L.

    In most cases hydrogen is the preferred fuel for use in the present generation of fuel cells being developed for commercial applications. Of all the potential sources of hydrogen, natural gas offers many advantages. It is widely available, clean, and can be converted to hydrogen relatively easily. When catalytic steam reforming is used to generate hydrogen from natural gas, it is essential that sulfur compounds in the natural gas are removed upstream of the reformer and various types of desulfurisation processes are available. In addition, the quality of fuel required for each type of fuel cell varies according to the anode material used, and the cell temperature. Low temperature cells will not tolerate high concentrations of carbon monoxide, whereas the molten fuel cell (MCFC) and solid oxide fuel cell (SOFC) anodes contain nickel on which it is possible to electrochemically oxidise carbon monoxide directly. The ability to internally reform fuel gas is a feature of the MCFC and SOFC. Internal reforming can give benefits in terms of increased electrical efficiency owing to the reduction in the required cell cooling and therefore parasitic system losses. Direct electrocatalysis of hydrocarbon oxidation has been the elusive goal of fuel cell developers over many years and recent laboratory results are encouraging. This paper reviews the principal methods of converting natural gas into hydrogen, namely catalytic steam reforming, autothermic reforming, pyrolysis and partial oxidation; it reviews currently available purification techniques and discusses some recent advances in internal reforming and the direct use of natural gas in fuel cells.

  13. Characterization of Ignalina NPP RBMK Reactors Graphite

    International Nuclear Information System (INIS)

    Hacker, P.J.; Neighbour, G.B.; Levinskas, R.; Milcius, D.

    2001-01-01

    The paper concentrates on the investigations of the initial physical properties of graphite used in production of graphite bricks of Ignalina NPP. These graphite bricks are used as nuclear moderator and major core structural components. Graphite bulk density is calculated by mensuration, pore volumes are measured by investigation of helium gas penetration in graphite pore network, the Young's modulus is determined using an ultrasonic time of flight method, the coefficient of thermal expansion is determined using a Netzsch dilatometer 402C, the fractured and machined graphite surfaces are studied using SEM, impurities are investigated qualitatively by EDAX, the degree of graphitization of the material is tested using X-ray diffraction. (author)

  14. Mechanical Properties of Super Duplex Stainless Steel 2507 after Gas Phase Thermal Precharging with Hydrogen

    Science.gov (United States)

    San Marchi, C.; Somerday, B. P.; Zelinski, J.; Tang, X.; Schiroky, G. H.

    2007-11-01

    Thermal precharging of super duplex stainless steel 2507 with 125 wppm hydrogen significantly reduced tensile ductility and fracture toughness. Strain-hardened 2507 exhibited more severe ductility loss compared to the annealed microstructure. The reduction of area (RA) was between 80 and 85 pct for both microstructures in the noncharged condition, while reductions of area were 25 and 46 pct for the strain-hardened and annealed microstructures, respectively, after hydrogen precharging. Similar to the effect of internal hydrogen on tensile ductility, fracture toughness of strain-hardened 2507 was lowered from nearly 300 MPa m1/2 in the noncharged condition to less than 60 MPa m1/2 in the hydrogen-precharged condition. While precharging 2507 with hydrogen results in a considerable reduction in ductility and toughness, the absolute values are similar to high-strength austenitic steels that have been tested under the same conditions, and which are generally considered acceptable for high-pressure hydrogen gas systems. The fracture mode in hydrogen-precharged 2507 involved cleavage cracking of the ferrite phase and ductile fracture along oblique planes in the austenite phase, compared to 100 pct microvoid coalescence in the absence of hydrogen. Predictions from a strain-based micromechanical fracture toughness model were in good agreement with the measured fracture toughness of hydrogen-precharged 2507, implying a governing role of austenite for resistance to hydrogen-assisted fracture.

  15. Variable composition hydrogen/natural gas mixtures for increased engine efficiency and decreased emissions

    Energy Technology Data Exchange (ETDEWEB)

    Sierens, R.; Rosseel, E.

    2000-01-01

    It is well known that adding hydrogen to natural gas extends the lean limit of combustion and that in this way extremely low emission levels can be obtained: even the equivalent zero emission vehicle (EZEV) requirements can be reached. The emissions reduction is especially important at light engine loads. In this paper results are presented for a GM V8 engine. Natural gas, pure hydrogen and different blends of these two fuels have been tested. The fuel supply system used provides natural gas/hydrogen mixtures in variable proportion, regulated independently of the engine operating condition. The influence of the fuel composition on the engine operating characteristics and exhaust emissions has been examined, mainly but not exclusively for 10 and 20% hydrogen addition. At least 10% hydrogen addition is necessary for a significant improvement in efficiency. Due to the conflicting requirements for low hydrocarbons and low NO{sub x} determining the optimum hythane composition is not straight-forward. For hythane mixtures with a high hydrogen fraction, it is found that a hydrogen content of 80% or less guarantees safe engine operation (no backfire nor knock), whatever the air excess factor. It is shown that to obtain maximum engine efficiency for the whole load range while taking low exhaust emissions into account, the mixture composition should be varied with respect to engine load.

  16. Hydrogen gas driven permeation through tungsten deposition layer formed by hydrogen plasma sputtering

    International Nuclear Information System (INIS)

    Uehara, Keiichiro; Katayama, Kazunari; Date, Hiroyuki; Fukada, Satoshi

    2015-01-01

    Highlights: • H permeation tests for W layer formed by H plasma sputtering are performed. • H permeation flux through W layer is larger than that through W bulk. • H diffusivity in W layer is smaller than that in W bulk. • The equilibrium H concentration in W layer is larger than that in W bulk. - Abstract: It is important to evaluate the influence of deposition layers formed on plasma facing wall on tritium permeation and tritium retention in the vessel of a fusion reactor from a viewpoint of safety. In this work, tungsten deposition layers having different thickness and porosity were formed on circular nickel plates by hydrogen RF plasma sputtering. Hydrogen permeation experiment was carried out at the temperature range from 250 °C to 500 °C and at hydrogen pressure range from 1013 Pa to 101,300 Pa. The hydrogen permeation flux through the nickel plate with tungsten deposition layer was significantly smaller than that through a bare nickel plate. This indicates that a rate-controlling step in hydrogen permeation was not permeation through the nickel plate but permeation though the deposition layer. The pressure dependence on the permeation flux differed by temperature. Hydrogen permeation flux through tungsten deposition layer is larger than that through tungsten bulk. From analysis of the permeation curves, it was indicated that hydrogen diffusivity in tungsten deposition layer is smaller than that in tungsten bulk and the equilibrium hydrogen concentration in tungsten deposition layer is enormously larger than that in tungsten bulk at same hydrogen pressure.

  17. PALLADIUM DOPED TIN OXIDE BASED HYDROGEN GAS SENSORS FOR SAFETY APPLICATIONS

    International Nuclear Information System (INIS)

    Kasthurirengan, S.; Behera, Upendra; Nadig, D. S.

    2010-01-01

    Hydrogen is considered to be a hazardous gas since it forms a flammable mixture between 4 to 75% by volume in air. Hence, the safety aspects of handling hydrogen are quite important. For this, ideally, highly selective, fast response, small size, hydrogen sensors are needed. Although sensors based on different technologies may be used, thin-film sensors based on palladium (Pd) are preferred due to their compactness and fast response. They detect hydrogen by monitoring the changes to the electrical, mechanical or optical properties of the films. We report the development of Pd-doped tin-oxide based gas sensors prepared on thin ceramic substrates with screen printed platinum (Pt) contacts and integrated nicrome wire heaters. The sensors are tested for their performances using hydrogen-nitrogen gas mixtures to a maximum of 4%H 2 in N 2 . The sensors detect hydrogen and their response times are less than a few seconds. Also, the sensor performance is not altered by the presence of helium in the test gas mixtures. By the above desired performance characteristics, field trials of these sensors have been undertaken. The paper presents the details of the sensor fabrication, electronic circuits, experimental setup for evaluation and the test results.

  18. Erosion of common structural materials and the degradation of suspended particles in flowing suspension of graphite powder in carbon dioxide gas

    International Nuclear Information System (INIS)

    Garton, D.A.; Hawes, R.I.; Rose, P.W.

    1968-06-01

    Experiments have been performed to examine the erosion of common materials of construction by a flowing suspension of graphite powder in carbon dioxide gas and the degradation of the graphite powder in the suspension. The suspension was circulated through a stainless steel loop at a pressure of 200 p.s.i.g. and bulk fluid temperature of 100-150 deg. C. No change in the weight of pins of mild steel, stainless steel and zircaloy, which were placed across the flow stream in a region where the velocity approached 100 ft./sec, could be detected after 350 hours of circulation. Examination of micro-photographs of the cross sections of the specimens showed no change in the structure of the metals. Considerable erosion of graphite pins producing a 6% decrease in the weight was observed under similar conditions. Detailed spectrographic analysis of the suspended powder taken at various times during the experiment showed no noticeable increase in the impurity content which could be attributed to erosion of the test specimens. A considerable increase in the tungsten, tin and cobalt concentration was observed and this is attributed to wear of the pump seal surfaces. The mean particle size of the suspended graphite powder was observed to decrease rapidly from 5 microns to 3 microns after only a few hours of circulation in the loop. After this initial period there was little further change in the particle size, the mean diameter being 2.85 microns after 167 hours of circulation. (author)

  19. Proposal for a Northeast Asian Hydrogen Highway: From a Natural-gas-based to a Hydrogen-based Society

    International Nuclear Information System (INIS)

    Kazuhiko O Hashi; Masaru Hirata; William C Leighty; D Eng

    2006-01-01

    In Northeast Asia, East Siberia and Sakhalin are rich in natural gas (NG). The environmental protection and energy security of the Northeast Asian region requires constructing an energy infrastructure network that can transport and distribute NG throughout the region in the near term, and renewable-source gaseous hydrogen (GH2) in the long term. We have promoted the construction of an NG pipeline network, the principal component of the energy infrastructure essential to our evolution toward a hydrogen-based society, through the Northeast Asia Natural Gas and Pipeline Forum (NAGPF). Our ultimate goal is a clean and sustainable society based on renewable energy sources, wherein hydrogen is produced from the vast potential of renewable energy in Siberia and China. The hydrogen thus produced would be transmitted through the pipeline network, progressively replacing NG as it is depleted. Over three-quarters of commercially exploitable hydroelectric power (hydro) resources of all Russia is in East Siberia. The areas from Kamchatka through the Kurilskiye Islands (called the Chishima Islands, in Japan) to Sakhalin is a world-class wind energy resource. West China has huge potential for solar energy. (authors)

  20. Hydrogen isotope inventory in the graphite divertor tiles of ASDEX Upgrade as measured by thermal desorption spectroscopy

    International Nuclear Information System (INIS)

    Franzen, P.; Behrisch, R.; Garcia-Rosales, C.; Schleussner, D.; Roesler, D.; Becker, J.; Knapp, W.; Edelmann, C.

    1997-01-01

    The hydrogen and deuterium inventories of the ASDEX Upgrade divertor tiles were measured after the experimental period from December 1994 to July 1995 by thermal desorption spectroscopy (TDS) of samples cut out of the divertor tiles. The samples were heated by electron bombardment up to 2100 K; the released gases were measured by means of a calibrated quadrupole mass spectrometer. The measured hydrogen or deuterium inventories are of the order of 10 23 m -2 . They are larger for samples of the inner divertor than of the outer divertor by a factor of about 2. The largest inventory was found at the separatrix position of the inner divertor. Most of the released hydrogen (H) can be attributed to water adsorbed in the near surface region during the air exposure prior to the TDS measurements. The total inventories measured by TDS exceed the inventories in the near surface region (< 25 μm) measured by ion beam analysis methods by a factor of up to 10. Hence, the total hydrogen retention is governed by the diffusion out of the near surface region deep into the material. The hydrogen and deuterium inventories decreased with increasing surface temperature. (author). 64 refs, 12 figs, 2 tabs

  1. In Situ Formation of AgCo Stabilized on Graphitic Carbon Nitride and Concomitant Hydrolysis of Ammonia Borane to Hydrogen.

    Science.gov (United States)

    Wang, Qi; Xu, Caili; Ming, Mei; Yang, Yingchun; Xu, Bin; Wang, Yi; Zhang, Yun; Wu, Jie; Fan, Guangyin

    2018-04-26

    The development of highly-efficient heterogeneous supported catalysts for catalytic hydrolysis of ammonia borane to yield hydrogen is of significant importance considering the versatile usages of hydrogen. Herein, we reported the in situ synthesis of AgCo bimetallic nanoparticles supported on g-C₃N₄ and concomitant hydrolysis of ammonia borane for hydrogen evolution at room temperature. The as-synthesized Ag 0.1 Co 0.9 /g-C₃N₄ catalysts displayed the highest turnover frequency (TOF) value of 249.02 mol H₂·(mol Ag ·min) −1 for hydrogen evolution from the hydrolysis of ammonia borane, which was higher than many other reported values. Furthermore, the Ag 0.1 Co 0.9 /g-C₃N₄ catalyst could be recycled during five consecutive runs. The study proves that Ag 0.1 Co 0.9 /g-C₃N₄ is a potential catalytic material toward the hydrolysis of ammonia borane for hydrogen production.

  2. In Situ Formation of AgCo Stabilized on Graphitic Carbon Nitride and Concomitant Hydrolysis of Ammonia Borane to Hydrogen

    Directory of Open Access Journals (Sweden)

    Qi Wang

    2018-04-01

    Full Text Available The development of highly-efficient heterogeneous supported catalysts for catalytic hydrolysis of ammonia borane to yield hydrogen is of significant importance considering the versatile usages of hydrogen. Herein, we reported the in situ synthesis of AgCo bimetallic nanoparticles supported on g-C3N4 and concomitant hydrolysis of ammonia borane for hydrogen evolution at room temperature. The as-synthesized Ag0.1Co0.9/g-C3N4 catalysts displayed the highest turnover frequency (TOF value of 249.02 mol H2·(molAg·min−1 for hydrogen evolution from the hydrolysis of ammonia borane, which was higher than many other reported values. Furthermore, the Ag0.1Co0.9/g-C3N4 catalyst could be recycled during five consecutive runs. The study proves that Ag0.1Co0.9/g-C3N4 is a potential catalytic material toward the hydrolysis of ammonia borane for hydrogen production.

  3. Heat pump cycle by hydrogen-absorbing alloys to assist high-temperature gas-cooled reactor in producing hydrogen

    International Nuclear Information System (INIS)

    Satoshi, Fukada; Nobutaka, Hayashi

    2010-01-01

    A chemical heat pump system using two hydrogen-absorbing alloys is proposed to utilise heat exhausted from a high-temperature source such as a high-temperature gas-cooled reactor (HTGR), more efficiently. The heat pump system is designed to produce H 2 based on the S-I cycle more efficiently. The overall system proposed here consists of HTGR, He gas turbines, chemical heat pumps and reaction vessels corresponding to the three-step decomposition reactions comprised in the S-I process. A fundamental research is experimentally performed on heat generation in a single bed packed with a hydrogen-absorbing alloy that may work at the H 2 production temperature. The hydrogen-absorbing alloy of Zr(V 1-x Fe x ) 2 is selected as a material that has a proper plateau pressure for the heat pump system operated between the input and output temperatures of HTGR and reaction vessels of the S-I cycle. Temperature jump due to heat generated when the alloy absorbs H 2 proves that the alloy-H 2 system can heat up the exhaust gas even at 600 deg. C without any external mechanical force. (authors)

  4. Raman characterization of bulk ferromagnetic nanostructured graphite

    International Nuclear Information System (INIS)

    Pardo, Helena; Divine Khan, Ngwashi; Faccio, Ricardo; Araújo-Moreira, F.M.; Fernández-Werner, Luciana

    2012-01-01

    Raman spectroscopy was used to characterize bulk ferromagnetic graphite samples prepared by controlled oxidation of commercial pristine graphite powder. The G:D band intensity ratio, the shape and position of the 2D band and the presence of a band around 2950 cm -1 showed a high degree of disorder in the modified graphite sample, with a significant presence of exposed edges of graphitic planes as well as a high degree of attached hydrogen atoms.

  5. Utilization of hydrogen gas production for electricity generation in ...

    African Journals Online (AJOL)

    Lecturer

    2012-05-03

    May 3, 2012 ... The main goals of this research were to use E. aerogenes ADH-43 for fermentation in order to decide the best carbon sources and ... by converting to electricity using fuel cells in 50 ml vial bottle, 2% total ... evolution compared with other biological hydrogen .... Erlenmeyer containing a solution of Ca (OH) 2.

  6. Informing hazardous zones for on-board maritime hydrogen liquid and gas systems

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, Myra L. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Pratt, Joseph William [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bran Anleu, Gabriela A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Proctor, Camron [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2018-01-01

    The significantly higher buoyancy of hydrogen compared to natural gas means that hazardous zones defined in the IGF code may be inaccurate if applied to hydrogen. This could place undue burden on ship design or could lead to situations that are unknowingly unsafe. We present dispersion analyses to examine three vessel case studies: (1) abnormal external vents of full blowdown of a liquid hydrogen tank due to a failed relief device in still air and with crosswind; (2) vents due to naturally-occurring boil-off of liquid within the tank; and (3) a leak from the pipes leading into the fuel cell room. The size of the hydrogen plumes resulting from a blowdown of the tank depend greatly on the wind conditions. It was also found that for normal operations releasing a small amount of "boil- off" gas to regulate the pressure in the tank does not create flammable concentrations.

  7. Removal of tritium from gas-cooled nuclear reactors

    International Nuclear Information System (INIS)

    Nieder, R.

    1976-01-01

    Tritium contained in the coolant gas in the primary circuit of a gas cooled nuclear reactor together with further tritium adsorbed on the graphite used as a moderator for the reactor is removed by introducing hydrogen or a hydrogen-containing compound, for example methane or ammonia, into the coolant gas. The addition of the hydrogen or hydrogen-containing compound to the coolant gas causes the adsorbed tritium to be released into the coolant gas and the tritium is then removed from the coolant gas by passing the mixture of coolant gas and hydrogen or hydrogen-containing compound through a gas purification plant before recirculating the coolant gas through the reactor. 14 claims, 1 drawing figure

  8. Comparison of hydrogen gas embrittlement of austenitic and ferritic stainless steels

    Science.gov (United States)

    Perng, T. P.; Altstetter, C. J.

    1987-01-01

    Hydrogen-induced slow crack growth (SCG) was compared in austenitic and ferritic stainless steels at 0 to 125 °Cand 11 to 216 kPa of hydrogen gas. No SCG was observed for AISI 310, while AISI 301 was more susceptible to hydrogen embrittlement and had higher cracking velocity than AL 29-4-2 under the same test conditions. The kinetics of crack propagation was modeled in terms of the hydrogen transport in these alloys. This is a function of temperature, microstructure, and stress state in the embrittlement region. The relatively high cracking velocity of AISI 301 was shown to be controlled by the fast transport of hydrogen through the stress-induced α' martensite at the crack tip and low escape rate of hydrogen through the γ phase in the surrounding region. Faster accumulation rates of hydrogen in the embrittlement region were expected for AISI 301, which led to higher cracking velocities. The mechanism of hydrogen-induced SCG was discussed based upon the concept of hydrogen-enhanced plasticity.

  9. Hydrogen enriched compressed natural gas (HCNG: A futuristic fuel for internal combustion engines

    Directory of Open Access Journals (Sweden)

    Nanthagopal Kasianantham

    2011-01-01

    Full Text Available Air pollution is fast becoming a serious global problem with increasing population and its subsequent demands. This has resulted in increased usage of hydrogen as fuel for internal combustion engines. Hydrogen resources are vast and it is considered as one of the most promising fuel for automotive sector. As the required hydrogen infrastructure and refueling stations are not meeting the demand, widespread introduction of hydrogen vehicles is not possible in the near future. One of the solutions for this hurdle is to blend hydrogen with methane. Such types of blends take benefit of the unique combustion properties of hydrogen and at the same time reduce the demand for pure hydrogen. Enriching natural gas with hydrogen could be a potential alternative to common hydrocarbon fuels for internal combustion engine applications. Many researchers are working on this for the last few years and work is now focused on how to use this kind of fuel to its maximum extent. This technical note is an assessment of HCNG usage in case of internal combustion engines. Several examples and their salient features have been discussed. Finally, overall effects of hydrogen addition on an engine fueled with HCNG under various conditions are illustrated. In addition, the scope and challenges being faced in this area of research are clearly described.

  10. Pressure of a partially ionized hydrogen gas : numerical results from exact low temperature expansions

    OpenAIRE

    Alastuey , Angel; Ballenegger , Vincent

    2010-01-01

    8 pages; International audience; We consider a partially ionized hydrogen gas at low densities, where it reduces almost to an ideal mixture made with hydrogen atoms in their ground-state, ionized protons and ionized electrons. By performing systematic low-temperature expansions within the physical picture, in which the system is described as a quantum electron-proton plasma interacting via the Coulomb potential, exact formulae for the first five leading corrections to the ideal Saha equation ...

  11. Treating landfill gas hydrogen sulphide with mineral wool waste (MWW) and rod mill waste (RMW).

    Science.gov (United States)

    Bergersen, Ove; Haarstad, Ketil

    2014-01-01

    Hydrogen sulphide (H2S) gas is a major odorant at municipal landfills. The gas can be generated from different waste fractions, for example demolition waste containing gypsum based plaster board. The removal of H2S from landfill gas was investigated by filtering it through mineral wool waste products. The flow of gas varied from 0.3 l/min to 3.0 l/min. The gas was typical for landfill gas with a mean H2S concentration of ca. 4500 ppm. The results show that the sulphide gas can effectively be removed by mineral wool waste products. The ratios of the estimated potential for sulphide precipitation were 19:1 for rod mill waste (RMW) and mineral wool waste (MWW). A filter consisting of a mixture of MWW and RMW, with a vertical perforated gas tube through the center of filter material and with a downward gas flow, removed 98% of the sulfide gas over a period of 80 days. A downward gas flow was more efficient in contacting the filter materials. Mineral wool waste products are effective in removing hydrogen sulphide from landfill gas given an adequate contact time and water content in the filter material. Based on the estimated sulphide removal potential of mineral wool and rod mill waste of 14 g/kg and 261 g/kg, and assuming an average sulphide gas concentration of 4500 ppm, the removal capacity in the filter materials has been estimated to last between 11 and 308 days. At the studied location the experimental gas flow was 100 times less than the actual gas flow. We believe that the system described here can be upscaled in order to treat this gas flow. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Determination of the hydrogen content of fuel elements

    International Nuclear Information System (INIS)

    Soare, M.; Petriu, F.; Toma, V.

    1995-01-01

    A new method and apparatus are reported for determination of the total hydrogen content by measurements on as-manufactured fuel elements, heated at prescribed temperature values between 200 degrees C and 600 degrees C. The method is based on the catalytic oxidation of the organic compounds and transformation of the hydrogen in the equivalent water quantity which is analysed by a special infrared detector. Different types of measurements for determination of the hydrogen content from graphite coating, UO 2 pellets and filling gas are presented. Also, experimental observation regarding water release and graphite thermal decomposition kinetic are discussed. (author)

  13. Fabrication of SnO2-Reduced Graphite Oxide Monolayer-Ordered Porous Film Gas Sensor with Tunable Sensitivity through Ultra-Violet Light Irradiation

    Science.gov (United States)

    Xu, Shipu; Sun, Fengqiang; Yang, Shumin; Pan, Zizhao; Long, Jinfeng; Gu, Fenglong

    2015-01-01

    A new graphene-based composite structure, monolayer-ordered macroporous film composed of a layer of orderly arranged macropores, was reported. As an example, SnO2-reduced graphite oxide monolayer-ordered macroporous film was fabricated on a ceramic tube substrate under the irradiation of ultra-violet light (UV), by taking the latex microsphere two-dimensional colloid crystal as a template. Graphite oxide sheets dispersed in SnSO4 aqueous solution exhibited excellent affinity with template microspheres and were in situ incorporated into the pore walls during UV-induced growth of SnO2. The growing and the as-formed SnO2, just like other photocatalytic semiconductor, could be excited to produce electrons and holes under UV irradiation. Electrons reduced GO and holes adsorbed corresponding negative ions, which changed the properties of the composite film. This film was directly used as gas-sensor and was able to display high sensitivity in detecting ethanol gas. More interestingly, on the basis of SnO2-induced photochemical behaviours, this sensor demonstrated tunable sensitivity when UV irradiation time was controlled during the fabrication process and post in water, respectively. This study provides efficient ways of conducting the in situ fabrication of a semiconductor-reduced graphite oxide film device with uniform surface structure and controllable properties. PMID:25758292

  14. The application of the pore population balance method to the calculation of the radiolytic weight loss and gas transport property changes of nuclear graphites

    International Nuclear Information System (INIS)

    Johnson, P.A.V.

    1982-01-01

    A pore population balance equation, previously used to describe the physical property changes of porous carbons during thermal oxidation in carbon dioxide, has been modified to treat the radiolytic oxidation of graphite in CO 2 /CO/CH 4 gas mixtures. Good agreement has been obtained between theory and experiment for the variation in the gas transport coefficients B, K and lambda of gilsonite graphite with absorbed radiation dose. Calculations indicate that the addition of blind pores to the transport porosity, and an allowance for the opening of closed pores with burn-off, do not account for the experimental fractional weight loss curve. An excellent fit is obtained, however, if a small volume of cylindrical pores of a mean radius approximately equal to the diffusion length of oxidising species in the coolant are present in the pore size spectrum. Gilsonite graphite therefore behaves as if the pore size distribution function is trimodal, with mean radii at about 0.5μm, 2.48μm and greater than or equal to 10.57μm. (author)

  15. Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

    KAUST Repository

    Logan, Bruce E.

    2008-12-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few years ago, rapid developments have led to hydrogen yields approaching 100%, energy yields based on electrical energy input many times greater than that possible by water electrolysis, and increased gas production rates. MECs used to make hydrogen gas are similar in design to microbial fuel cells (MFCs) that produce electricity, but there are important differences in architecture and analytical methods used to evaluate performance. We review here the materials, architectures, performance, and energy efficiencies of these MEC systems that show promise as a method for renewable and sustainable energy production, and wastewater treatment. © 2008 American Chemical Society.

  16. Improved speed of hydrogen detection by Schottky diodes on InP with electrophoretically deposited Pt nanoparticles and graphite contacts

    Czech Academy of Sciences Publication Activity Database

    Žďánský, Karel; Dickerson, J.H.

    -, č. 184 (2013), s. 295-300 ISSN 0925-4005 R&D Projects: GA MŠk(CZ) OC10021 Institutional support: RVO:67985882 Keywords : Metal nanoparticles * Keyed electrophoresis * Hydrogen sensors Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 3.840, year: 2013

  17. Gas Phase Fabrication of Pd-Ni Nanoparticle Arrays for Hydrogen Sensor Applications

    Directory of Open Access Journals (Sweden)

    Peng Xing

    2015-01-01

    Full Text Available Pd-Ni nanoparticles have been fabricated by gas aggregation process. The formation of Pd-Ni nano-alloys was confirmed by X-ray photoelectron spectroscopy measurements. By depositing Pd-Ni nanoparticles on the interdigital electrodes, quantum conductance-based hydrogen sensors were fabricated. The Ni content in the nanoparticle showed an obvious effect on the hydrogen response behavior corresponding to the conductance change of the nanoparticle film. Three typical response regions with different conductance-hydrogen pressure correlations were observed. It was found that the α-β phase transition region of palladium hydride moves to significant higher hydrogen pressure with the addition of nickel element, which greatly enhance the hydrogen sensing performance of the nanoparticle film.

  18. Combustion characteristics of natural gas-hydrogen hybrid fuel turbulent diffusion flame

    Energy Technology Data Exchange (ETDEWEB)

    El-Ghafour, S.A.A.; El-dein, A.H.E.; Aref, A.A.R. [Mechanical Power Engineering Department, Faculty of Engineering, Suez Canal University, Port-Said (Egypt)

    2010-03-15

    Combustion characteristics of natural gas - hydrogen hybrid fuel were investigated experimentally in a free jet turbulent diffusion flame flowing into a slow co-flowing air stream. Experiments were carried out at a constant jet exit Reynolds number of 4000 and with a wide range of NG-H{sub 2} mixture concentrations, varied from 100%NG to 50%NG-50% H{sub 2} by volume. The effect of hydrogen addition on flame stability, flame length, flame structure, exhaust species concentration and pollutant emissions was conducted. Results showed that, hydrogen addition sustains a progressive improvement in flame stability and reduction in flame length, especially for relatively high hydrogen concentrations. Hydrogen-enriched flames found to have a higher combustion temperatures and reactivity than natural gas flame. Also, it was found that hydrogen addition to natural gas is an ineffective strategy for NO and CO reduction in the studied range, while a significant reduction in the %CO{sub 2} molar concentration by about 30% was achieved. (author)

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

    Science.gov (United States)

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

    2017-07-01

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

  20. Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

    Energy Technology Data Exchange (ETDEWEB)

    Dadfarnia, Mohsen (University of Illinois at Urbana-Champaign, Urbana, IL); Nibur, Kevin A.; San Marchi, Christopher W.; Sofronis, Petros (University of Illinois at Urbana-Champaign, Urbana, IL); Somerday, Brian P.; Foulk, James W., III; Hayden, Gary A. (CP Industries, McKeesport, PA)

    2010-07-01

    Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

  1. Problems of hydrogen - water vapor - inert gas mixture use in heavy liquid metal coolant technology

    International Nuclear Information System (INIS)

    Ul'yanov, V.V.; Martynov, P.N.; Gulevskij, V.A.; Teplyakov, Yu.A.; Fomin, A.S.

    2014-01-01

    The reasons of slag deposit formation in circulation circuits with heavy liquid metal coolants, which can cause reactor core blockage, are considered. To prevent formation of deposits hydrogen purification of coolant and surfaces of circulation circuit is used. It consists in introduction of gaseous mixtures hydrogen - water vapor - rare gas (argon or helium) directly into coolant flow. The principle scheme of hydrogen purification and the processes occurring during it are under consideration. Measures which make it completely impossible to overlap of the flow cross section of reactor core, steam generators, pumps and other equipment by lead oxides in reactor facilities with heavy liquid metal coolants are listed [ru

  2. Hydrogen

    Directory of Open Access Journals (Sweden)

    John O’M. Bockris

    2011-11-01

    Full Text Available The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan. Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  3. Numerical estimation of ultrasonic production of hydrogen: Effect of ideal and real gas based models.

    Science.gov (United States)

    Kerboua, Kaouther; Hamdaoui, Oualid

    2018-01-01

    Based on two different assumptions regarding the equation describing the state of the gases within an acoustic cavitation bubble, this paper studies the sonochemical production of hydrogen, through two numerical models treating the evolution of a chemical mechanism within a single bubble saturated with oxygen during an oscillation cycle in water. The first approach is built on an ideal gas model, while the second one is founded on Van der Waals equation, and the main objective was to analyze the effect of the considered state equation on the ultrasonic hydrogen production retrieved by simulation under various operating conditions. The obtained results show that even when the second approach gives higher values of temperature, pressure and total free radicals production, yield of hydrogen does not follow the same trend. When comparing the results released by both models regarding hydrogen production, it was noticed that the ratio of the molar amount of hydrogen is frequency and acoustic amplitude dependent. The use of Van der Waals equation leads to higher quantities of hydrogen under low acoustic amplitude and high frequencies, while employing ideal gas law based model gains the upper hand regarding hydrogen production at low frequencies and high acoustic amplitudes. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Development of a new method for hydrogen isotope analysis of trace hydrocarbons in natural gas samples

    Directory of Open Access Journals (Sweden)

    Xibin Wang

    2016-12-01

    Full Text Available A new method had been developed for the analysis of hydrogen isotopic composition of trace hydrocarbons in natural gas samples by using solid phase microextraction (SPME combined with gas chromatography-isotope ratio mass spectrometry (GC/IRMS. In this study, the SPME technique had been initially introduced to achieve the enrichment of trace content of hydrocarbons with low abundance and coupled to GC/IRMS for hydrogen isotopic analysis. The main parameters, including the equilibration time, extraction temperature, and the fiber type, were systematically optimized. The results not only demonstrated that high extraction yield was true but also shows that the hydrogen isotopic fractionation was not observed during the extraction process, when the SPME device fitted with polydimethylsiloxane/divinylbenzene/carbon molecular sieve (PDMS/DVB/CAR fiber. The applications of SPME-GC/IRMS method were evaluated by using natural gas samples collected from different sedimentary basins; the standard deviation (SD was better than 4‰ for reproducible measurements; and also, the hydrogen isotope values from C1 to C9 can be obtained with satisfying repeatability. The SPME-GC/IRMS method fitted with PDMS/DVB/CAR fiber is well suited for the preconcentration of trace hydrocarbons, and provides a reliable hydrogen isotopic analysis for trace hydrocarbons in natural gas samples.

  5. Electrochemical characteristics of silver- and nickel-coated synthetic graphite prepared by a gas suspension spray coating method for the anode of lithium secondary batteries

    International Nuclear Information System (INIS)

    Choi, Won Chang; Byun, Dongjin; Lee, Joong Kee; Cho, Byung won

    2004-01-01

    Four kinds of synthetic graphite coated with silver and nickel for the anodes of lithium secondary batteries were prepared by a gas suspension spray coating method. The electrode coated with silver showed higher charge-discharge capacities due to a Ag-Li alloy, but rate capability decreased at higher charge-discharge rate. This result can be explained by the formation of an artificial Ag oxidation film with higher impedance, this lowered the rate capability at high charge-discharge rate due to its low electrical conductivity. Rate capability is improved, however, by coating nickel and silver together on the surface of synthetic graphite. The nickel which is inactive with oxidation reaction plays an important role as a conducting agent which enhanced the conductivity of the electrode

  6. Development of the Raman lidar system for remote hydrogen gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Choi, In Young; Baik, Sung Hoon; Park, Seung Kyu; Park, Nak Gyu; Choi, Young Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Detection of hydrogen (H{sub 2}) gas leakage is very important for safety of the nuclear power plant because H{sub 2} gas is very flammable and explosive. H{sub 2} gas is generated by oxidizing the nuclear fuel cladding during the critical accident and generated H{sub 2} gas leads to serious secondary damages in the containment building of nuclear power plant. Thus, various H{sub 2} gas detection techniques are used in the nuclear power plant such as catalytic combustion sensors, semiconducting oxide sensors, thermal conductivity sensors and electrochemical sensor. A Raman lidar (Light Detection And Ranging) system for remote detection of the H{sub 2} gas can cover the area in the containment building of a nuclear power plant. H{sub 2} gas has a very strong Raman Effect, and H{sub 2} Raman cells have been widely used for laser wavelength conversion. In this study, Raman lidar system was developed for H{sub 2} gas detection used in the containment building of nuclear power plant. In this study, remote hydrogen gas detection devices and measuring algorithm are developed by using the Raman lidar method. Through the experiment, we proved that our developed Raman lidar system was possible to measure the N{sub 2} and H{sub 2} gas scattering signal remotely.

  7. Real gas CFD simulations of hydrogen/oxygen supercritical combustion

    Science.gov (United States)

    Pohl, S.; Jarczyk, M.; Pfitzner, M.; Rogg, B.

    2013-03-01

    A comprehensive numerical framework has been established to simulate reacting flows under conditions typically encountered in rocket combustion chambers. The model implemented into the commercial CFD Code ANSYS CFX includes appropriate real gas relations based on the volume-corrected Peng-Robinson (PR) equation of state (EOS) for the flow field and a real gas extension of the laminar flamelet combustion model. The results indicate that the real gas relations have a considerably larger impact on the flow field than on the detailed flame structure. Generally, a realistic flame shape could be achieved for the real gas approach compared to experimental data from the Mascotte test rig V03 operated at ONERA when the differential diffusion processes were only considered within the flame zone.

  8. Adsorption of hydrogen sulfide gas on several synthetic zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Fukui, T; Ise, Y; Boki, K; Tanada, S

    1974-07-01

    Ten kinds of synthetic zeolites were tested to determine the most suitable adsorbent for H/sub 2/S gas removal by a dry process. Specific surface area with argon gas and H/sub 2/S gas, surface pH, and thermodynamic data of adsorbents were measured. The amounts of H/sub 2/S gas adsorbed on synthetic zeolite adsorbents were affected in terms of the pore sizes of the adsorbents rather than the surface pH and the thermodynamic factors. The adsorbents No. 3, No. 7, and No. 8 showed higher adsorption of H/sub 2/S than the other adsorbents and were the most suitable for practical purposes.

  9. A compressed hydrogen gas storage system with an integrated phase change material

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rothuizen, Erasmus Damgaard; Jørgensen, Jens Erik

    2015-01-01

    below the critical temperature of 85 °C, while filling the hydrogen at ambient temperature. Results show that a 10-mm-thick layer of paraffin wax can absorb enough heat to reduce the adiabatic temperature by 20 K when compared to a standard Type IV tank. The heat transfer from the gas to the phase...... change material, mainly occurs after the fueling is completed, resulting in a higher hydrogen peak temperature inside the tank and a lower fuelled mass than a gas-cooled system. Such a mass reduction accounts for 12% with respect to the case of a standard tank system fuelled at -40 °C....

  10. Radioactive gas and hydrogen removal after a LOCE at the LOFT Facility

    International Nuclear Information System (INIS)

    McCormick-Barger, J.W.; Sumpter, K.C.

    1979-01-01

    The use of a silver-zeolite halogen adsorber placed in series with a hydrogen catalytic recombiner and a cryogenic noble gas adsorber assembly constitutes a waste gas processing system (WGPS) capable of handling hydrogen and fission product gases following a Loss-of-Coolant Experiment (LOCE). This paper describes: the types and quantities of gases expected to be found at the facility after a failed-fuel LOCE; the purpose of the WGPS; and the general configuration and expected decontamination factors associated with the LOFT WGPS

  11. Studies on the separation of hydrogen isotopes and spin isomers by gas chromatography

    International Nuclear Information System (INIS)

    Pushpa, K.K.; Annaji Rao, K.

    2000-08-01

    Separation and analysis of mixture of hydrogen isotopes has gained considerable importance because of various applications needing different isotopes in lasers, nuclear reactions and tracer or labelled compounds. In the literature gas chromatographic methods are reported using columns packed with partly dehydrated or thoroughly dehydrated alumina/molecular sieve stationary phase at 77 deg K with helium, neon and even hydrogen or deuterium as carrier gas. In the present study an attempt is made to compare the chromatographic behaviour of these two stationary phases using virgin and Fe doped form in partly dehydrated and thoroughly dehydrated state, using helium, neon, hydrogen and deuterium as carrier gas. The results of this study show that helium or neon carrier gas behave similarly broad peaks with some tailing. Sharp symmetric peaks are obtained with hydrogen or deuterium carrier gas. This is attributed to large hold up capacity for H 2 or D 2 at 77 deg K in these materials as compared to helium or neon. Spin isomers of H 2 or D 2 are separated on Fe free stationary phases, though ortho H 2 and HD are not resolved. Using a combination of Fe doped short column and plain alumina column, both maintained in dehydrated form, the effect of Fe doping on thermal equilibrium of ortho/para forms at 77 deg K is clearly demonstrated. (author)

  12. Effect of bioleaching on hydrogen-rich gas production by steam gasification of sewage sludge

    International Nuclear Information System (INIS)

    Li, Hanhui; Chen, Zhihua; Huo, Chan; Hu, Mian; Guo, Dabin; Xiao, Bo

    2015-01-01

    Highlights: • Bioleaching can modify the physicochemical property of sewage sludge. • The enhancement is mainly hydrogen. • Bioleaching can enhance the gas production in gasification of sewage sludge. • Study provides an insight for future application of bioleached sewage sludge. - Abstract: Effect of bioleaching on hydrogen-rich gas production by steam gasification of sewage sludge was carried out in a lab-scale fixed-bed reactor. The influence of sewage sludge solids concentrations (6–14% (w/v) in 2% increments) during the bioleaching process and reactor temperature (600–900 °C in 100 °C increments) on gasification product yields and gas composition were studied. Characterization of samples showed that bioleaching treatment, especially in 6% (w/v) sludge solids concentration, led to metal removal effectively and modifications in the physicochemical property of sewage sludge which was favored for gasification. The maximum gas yield (49.4%) and hydrogen content (46.4%) were obtained at 6% (w/v) sludge solids concentration and reactor temperature of 900 °C. Sewage sludge after the bioleaching treatment may be a feasible feedstock for hydrogen-rich gas product.

  13. The effect of hydrogen enrichment towards the flammability limits of natural gas in conventional combustion

    International Nuclear Information System (INIS)

    Izirwan Izhab; Nur Syuhada Mohd Shokri; Nurul Saadah Sulaiman; Mohd Zulkifli Mohamad Noor; Siti Zubaidah Sulaiman; Rosmawati Naim; Norida Ridzuan, Mohd Masri Razak; Abdul Halim Abdul Razik; Zulkafli Hassan

    2010-01-01

    The use of hydrogenated fuels shows a considerable promise for the applications in gas turbines and internal combustion engines. The aims of this study are to determine the flammability limits of natural gas/ air mixtures and to investigate the effect of hydrogen enrichment on the flammability limits of natural gas/ air mixtures up to 60 vol % of hydrogen/fuel volume ratio at atmospheric pressure and ambient temperature. The experiments were performed in a 20 L closed explosion vessel where the mixtures were ignited by using a spark permanent wire that was placed at the centre of the vessel. The pressure-time variations during explosions of natural gas/ air mixtures in an explosion vessel were recorded. Moreover, the explosion pressure data is used to determine the flammability limits that flame propagation is considered to occur if explosion pressure is greater than 0.1 bar. Therefore, in this study, the results show that the range of flammability limits are from 6 vol % to 15 vol % and by the addition of hydrogen in natural gas proved to extend the initial lower flammability limit of 6 vol % to 2 vol % of methane. (author)

  14. Deposition of tantalum carbide coatings on graphite by laser interactions

    Science.gov (United States)

    Veligdan, James; Branch, D.; Vanier, P. E.; Barietta, R. E.

    1994-01-01

    Graphite surfaces can be hardened and protected from erosion by hydrogen at high temperatures by refractory metal carbide coatings, which are usually prepared by chemical vapor deposition (CVD) or chemical vapor reaction (CVR) methods. These techniques rely on heating the substrate to a temperature where a volatile metal halide decomposes and reacts with either a hydrocarbon gas or with carbon from the substrate. For CVR techniques, deposition temperatures must be in excess of 2000 C in order to achieve favorable deposition kinetics. In an effort to lower the bulk substrate deposition temperature, the use of laser interactions with both the substrate and the metal halide deposition gas has been employed. Initial testing involved the use of a CO2 laser to heat the surface of a graphite substrate and a KrF excimer laser to accomplish a photodecomposition of TaCl5 gas near the substrate. The results of preliminary experiments using these techniques are described.

  15. The use of the natural-gas pipeline infrastructure for hydrogen transport in a changing market structure

    International Nuclear Information System (INIS)

    Haeseldonckx, Dries; D'haeseleer, William

    2007-01-01

    In this paper, the transport and distribution aspects of hydrogen during the transition period towards a possible full-blown hydrogen economy are carefully looked at. Firstly, the energetic and material aspects of hydrogen transport through the existing natural-gas (NG) pipeline infrastructure is discussed. Hereby, only the use of centrifugal compressors and the short-term security of supply seem to constitute a problem for the NG to hydrogen transition. Subsequently, the possibility of percentwise mixing of hydrogen into the NG bulk is dealt with. Mixtures containing up to 17 vol% of hydrogen should not cause difficulties. As soon as more hydrogen is injected, replacement of end-use applications and some pipelines will be necessary. Finally, the transition towards full-blown hydrogen transport in (previously carrying) NG pipelines is treated. Some policy guidelines are offered, both in a regulated and a liberalised energy (gas) market. As a conclusion, it can be stated that the use of hydrogen-natural gas mixtures seems well suited for the transition from natural gas to hydrogen on a distribution (low pressure) level. However, getting the hydrogen gas to the distribution grid, by means of the transport grid, remains a major issue. In the end, the structure of the market, regulated or liberalised, turns out not to be important. (author)

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

    International Nuclear Information System (INIS)

    Nagel, David J.

    2015-01-01

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

  17. Chemically modified glasses for analysis of hydrogen isotopes by gas-chromatography

    International Nuclear Information System (INIS)

    Stanciu, Vasile; Stefanescu, Doina

    1999-01-01

    Hydrogen isotope separation process by such methods as cryogenic distillation or thermal diffusion method is one of the key technologies of the tritium separation from heavy water of CANDU reactors and in the tritium fuel cycle for a thermonuclear fusion reactor. In each process, the analytical techniques for measuring contents of hydrogen isotope mixture are necessary. An extensive experimental research has been carried out in order to produce the most suitable absorbent and define the best operating conditions for selective separation and analysis of hydrogen isotope by gas-chromatography. This paper describes the preparation of adsorbent materials utilised as stationary phase in the gas-chromatographic column for hydrogen isotope separation and treatment (activation) of stationary phase. Modified thermo-resisting glass with Fe(NH 4 ) 2 (SO 4 ) 2 6H 2 O and Cr 2 O 3 , respectively, have been experimentally investigated at 77 K for H 2 , HD and D 2 separation and the results of chromatographic runs are also reported and discussed. The gas-chromatographic apparatus used is composed of a Hewlett-Packard 7620A gas-chromatograph equipped with a gas carrier flow rate controller and a thermal conductivity detector (TCD). The apparatus comprises also a Dewar vessel containing the separation column. The hydrogen isotopes H 2 , HD, D 2 and their mixture have been obtained in our laboratories. The best operating conditions of the adsorbent column Fe (III)/glass and Cr 2 O 3 /glass, i.e. granulometry, column length, pressure-drop along the column, carrier gas flow rate, sample volume have been studied by means of the analysis of the retention times, separation factors and HETP. (authors)

  18. Metal/glass composites for analysis of hydrogen isotopes by gas-chromatography

    International Nuclear Information System (INIS)

    Nicolae, Constantin Adrian; Sisu, Claudia; Stefanescu, Doina; Stanciu, Vasile

    1999-01-01

    The separation process of hydrogen isotopes by cryogenic distillation or thermal diffusion is a key technology for tritium separation from heavy water in CANDU reactor and for tritium fuel cycle in thermonuclear fusion reactor. In each process, analytical techniques for analyzing the hydrogen isotope mixture are required. An extensive experimental research has been carried out in order to produce the most suitable adsorbents and to establish the best operating conditions for selective separation and analysis of hydrogen isotopes by gas-chromatography. This paper describes the preparation of adsorbent materials used as stationary phases in the gas-chromatographic column for hydrogen isotope separation and the treatment (activation) of stationary phases. Modified thermoresisting glass with Fe(NH 4 ) 2 (SO 4 ) 2 ·6H 2 O and Cr 2 O 3 respectively have been experimentally investigated at 77 K for H 2 , HD and D 2 separation and the results of chromatographic runs are reported and discussed. The gas-chromatographic apparatus used in this study is composed of a Hewlett-Packard 7620A gas-chromatograph equipped with a gas carrier flow rate controller and a thermal conductivity detector. The apparatus comprises also a Dewar vessel containing the separation column. The hydrogen isotopes, H 2 , HD, D 2 , and their mixture have been obtained in our laboratories. The best operating conditions and parameters of the Fe 3+ /glass adsorbent column , i.e. granulometry, column length, pressure-drop along the column, carrier gas flow rate and sample volume have been studied by means of the analysis of the retention times, separation factors and HETP. (authors)

  19. Comparison of thermodynamic and environmental indexes of natural gas, syngas and hydrogen production processes

    International Nuclear Information System (INIS)

    Bargigli, Silvia; Raugei, Marco; Ulgiati, Sergio

    2004-01-01

    The thermodynamic efficiency and the environmental sustainability of selected processes that deliver gaseous energy carriers (natural gas, syngas from coal gasification, and hydrogen from steam reforming of natural gas and alkaline electrolysis) is explored by means of a multi-criteria, multi-scale approach based on four methods: material flow accounting, energy analysis, exergy analysis, and energy synthesis. The average energy and exergy conversion efficiencies of syngas (76% and 75%, respectively) are found to be higher than those for hydrogen (64% and 55%). However, coal-to-syngas conversion generates a significant amount of solid waste, which should be dealt with carefully. In addition, the material intensity is much higher for syngas (e.g. abiotic MI=768 g/g) than for natural gas and hydrogen (21 and 39 g/g, respectively), indicating a higher load on the environment. On the other hand, the energy intensity (transformity) for syngas (5.25x10 4 seJ/J) is shown to be lower than for hydrogen (9.66x10 4 seJ/J), indicating a lower demand for global environmental support. Therefore, material intensities and transformities offer two complementary pieces of information: transformities account for the 'memory' of the environmental resources that were used up in the past for the production of the inputs, whereas MIs are strictly calculated within the time frame of the life cycle of the investigated process. The higher transformity values calculated for pure hydrogen suggest careful and appropriate use of such an energy vector

  20. Hydrogen Separation by Natural Zeolite Composite Membranes: Single and Multicomponent Gas Transport

    Directory of Open Access Journals (Sweden)

    Afrooz Farjoo

    2017-10-01

    Full Text Available Single and multicomponent gas permeation tests were used to evaluate the performance of metal-supported clinoptilolite membranes. The efficiency of hydrogen separation from lower hydrocarbons (methane, ethane, and ethylene was studied within the temperature and pressure ranges of 25–600 °C and 110–160 kPa, respectively. The hydrogen separation factor was found to reduce noticeably in the gas mixture compared with single gas experiments at 25 °C. The difference between the single and multicomponent gas results decreased as the temperature increased to higher than 300 °C, which is when the competitive adsorption–diffusion mechanism was replaced by Knudsen diffusion or activated diffusion mechanisms. To evaluate the effect of gas adsorption, the zeolite surface isotherms of each gas in the mixture were obtained from 25 °C to 600 °C. The results indicated negligible adsorption of individual gases at temperatures higher than 300 °C. Increasing the feed pressure resulted in a higher separation efficiency for the individual gases compared with the multicomponent mixture, due to the governing effect of the adsorptive mechanism. This study provides valuable insight into the application of natural zeolites for the separation of hydrogen from a mixture of hydrocarbons.

  1. Hydrogen Separation by Natural Zeolite Composite Membranes: Single and Multicomponent Gas Transport.

    Science.gov (United States)

    Farjoo, Afrooz; Kuznicki, Steve M; Sadrzadeh, Mohtada

    2017-10-06

    Single and multicomponent gas permeation tests were used to evaluate the performance of metal-supported clinoptilolite membranes. The efficiency of hydrogen separation from lower hydrocarbons (methane, ethane, and ethylene) was studied within the temperature and pressure ranges of 25-600 °C and 110-160 kPa, respectively. The hydrogen separation factor was found to reduce noticeably in the gas mixture compared with single gas experiments at 25 °C. The difference between the single and multicomponent gas results decreased as the temperature increased to higher than 300 °C, which is when the competitive adsorption-diffusion mechanism was replaced by Knudsen diffusion or activated diffusion mechanisms. To evaluate the effect of gas adsorption, the zeolite surface isotherms of each gas in the mixture were obtained from 25 °C to 600 °C. The results indicated negligible adsorption of individual gases at temperatures higher than 300 °C. Increasing the feed pressure resulted in a higher separation efficiency for the individual gases compared with the multicomponent mixture, due to the governing effect of the adsorptive mechanism. This study provides valuable insight into the application of natural zeolites for the separation of hydrogen from a mixture of hydrocarbons.

  2. A fatigue initiation parameter for gas pipe steel submitted to hydrogen absorption

    Energy Technology Data Exchange (ETDEWEB)

    Capelle, J; Gilgert, J; Pluvinage, G [LaBPS - Ecole Nationale d' Ingenieurs de Metz et Universite Paul Verlaine Metz, Ile du Saulcy, 57045 Metz (France)

    2010-01-15

    Fatigue initiation resistance has been determined on API 5L X52 gas pipe steel. Tests have been performed on Roman Tile (RT) specimen and fatigue initiation was detected by acoustic emission. A comparison between specimens electrolytically charged with hydrogen and specimens without hydrogen absorption were made and it has been noted that fatigue initiation time is reduced of about 3 times when hydrogen embrittlement occurs. It has been proposed to use the concept of Notch Stress Intensity Factor as parameter to describe the fatigue initiation process. Due to the fact that hydrogen is localised in area with high hydrostatic pressure, definitions of local effective stress and distance have been modified when hydrogen is absorbed. This modification can be explained by existence of a ductile-brittle transition with hydrogen concentration. The fatigue initiation resistance curve allows that to determine a threshold for large number of cycles of fatigue non initiation. This parameter introduced in a Failure Assessment Diagram (FAD) provides supplementary information about defect nocivity in gas pipes: a non-critical defect can be detected as dormant or not dormant defect i.e., as non propagating defect. (author)

  3. Natural gas usage as a heat source for integrated SMR and thermochemical hydrogen production technologies

    International Nuclear Information System (INIS)

    Jaber, O.; Naterer, G.F.; Dincer, I.

    2010-01-01

    This paper investigates various usages of natural gas (NG) as an energy source for different hydrogen production technologies. A comparison is made between the different methods of hydrogen production, based on the total amount of natural gas needed to produce a specific quantity of hydrogen, carbon dioxide emissions per mole of hydrogen produced, water requirements per mole of hydrogen produced, and a cost sensitivity analysis that takes into account the fuel cost, carbon dioxide capture cost and a carbon tax. The methods examined are the copper-chlorine (Cu-Cl) thermochemical cycle, steam methane reforming (SMR) and a modified sulfur-iodine (S-I) thermochemical cycle. Also, an integrated Cu-Cl/SMR plant is examined to show the unique advantages of modifying existing SMR plants with new hydrogen production technology. The analysis shows that the thermochemical Cu-Cl cycle out-performs the other conventional methods with respect to fuel requirements, carbon dioxide emissions and total cost of production. (author)

  4. Oxidation of PCEA nuclear graphite by low water concentrations in helium

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I., E-mail: ContescuCI@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6087 (United States); Mee, Robert W. [Department of Business Analytics and Statistics, University of Tennessee, Knoxville, TN 37996-0525 (United States); Wang, Peng [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6087 (United States); Romanova, Anna V.; Burchell, Timothy D. [Department of Business Analytics and Statistics, University of Tennessee, Knoxville, TN 37996-0525 (United States)

    2014-10-15

    Accelerated oxidation tests were performed to determine kinetic parameters of the chronic oxidation reaction (i.e. slow, continuous, and persistent) of PCEA graphite in contact with helium coolant containing low moisture concentrations in high temperature gas-cooled reactors. To the authors’ knowledge such a study has not been done since the detailed analysis of reaction of H-451 graphite with steam (Velasquez, Hightower, Burnette, 1978). Since that H-451 graphite is now unavailable, it is urgently needed to characterize chronic oxidation behavior of new graphite grades that are being considered for use in gas-cooled reactors. The Langmuir–Hinshelwood mechanism of carbon oxidation by water results in a non-linear reaction rate expression, with at least six different parameters. They were determined in accelerated oxidation experiments that covered a large range of temperatures (800–1100 °C), and partial pressures of water (15–850 Pa) and hydrogen (30–150 Pa) and used graphite specimens thin enough (4 mm) in order to avoid diffusion effects. Data analysis employed a statistical method based on multiple likelihood estimation of parameters and simultaneous fitting of non-linear equations. The results show significant material-specific differences between graphite grades PCEA and H-451 which were attributed to microstructural dissimilarity between the two materials. It is concluded that kinetic data cannot be transferred from one graphite grade to another.

  5. Some economic aspects of natural uranium graphite gas reactor types. Present status and trends of costs in France; Quelques aspects economiques de la filiere uranium naturel - Graphite - gaz. Etat actuel et tendance des couts en France

    Energy Technology Data Exchange (ETDEWEB)

    Gaussens, J; Tanguy, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Leo, B [Electricite de France (EDF), 75 - Paris (France)

    1964-07-01

    The first part of this report defines the economic advantages of natural uranium fuels, which are as follows: the restricted number and relatively simple fabrication processes of the fuel elements, the low cost per kWh of the finished product and the reasonable capital investments involved in this type of fuel cycle as compared to that of enriched uranium. All these factors combine to reduce the arbitrary nature of cost estimates, which is particularly marked in the case of enriched uranium due to the complexity of its cycle and the uncertainties of plutonium prices). Finally, the wide availability of yellowcake, as opposed to the present day virtual monopoly of isotope separation, and the low cost of natural uranium stockpiling, offer appreciable guarantees in the way of security of supply and economic and political independence as compared with the use of enriched uranium. As far as overall capital investments are concerned, it is shown that, although graphite-gas reactor costs are higher than those of light water reactors in certain capacity ranges, the situation becomes far less clear when we start taking into account, in the interest of national independence, the cost of nuclear fuel production equipment in the case of each of these types of reactor. Finally, the marginal cost of the power capacity of a graphite-gas reactor is low and its technological limitations have receded (owing particularly to the use of prestressed concrete). It is a well known fact that the trend is now towards larger power station units, which means that the rentability of natural uranium graphite reactors as compared to other types of reactors will become more and more pronounced. The second section aims at presenting a realistic short and medium term view of the fuel, running, and investment costs of French natural uranium graphite gas, reactors. Finally, the economic goals which this type of reactor can reach in the very near future are given. It is thus shown that considerable

  6. Stability of MOF-5 in a hydrogen gas environment containing fueling station impurities

    DEFF Research Database (Denmark)

    Ming, Yang; Purewal, Justin; Yang, Jun

    2016-01-01

    , HCl, H2O, CO, CO2, CH4, O2, N2, and He) to pure hydrogen gas. Subsequently, MOF-5 was exposed to these mixtures over hundreds of adsorption/desorption pressure-swing cycles and for extended periods of static exposure. The impact of exposure was assessed by periodically measuring the hydrogen storage...... of these contaminants on MOFs is mostly unknown. In the present study MOF-5 is adopted as a prototypical moisture-sensitive hydrogen storage material. Five “impure” gas mixtures were prepared by introducing low-to-moderate levels (i.e., up to ∼200 times greater than the J2719 limit) of selected contaminants (NH3, H2S...

  7. Dominant rate process of silicon surface etching by hydrogen chloride gas

    International Nuclear Information System (INIS)

    Habuka, Hitoshi; Suzuki, Takahiro; Yamamoto, Sunao; Nakamura, Akio; Takeuchi, Takashi; Aihara, Masahiko

    2005-01-01

    Silicon surface etching and its dominant rate process are studied using hydrogen chloride gas in a wide concentration range of 1-100% in ambient hydrogen at atmospheric pressure in a temperature range of 1023-1423 K, linked with the numerical calculation accounting for the transport phenomena and the surface chemical reaction in the entire reactor. The etch rate, the gaseous products and the surface morphology are experimentally evaluated. The dominant rate equation accounting for the first-order successive reactions at silicon surface by hydrogen chloride gas is shown to be valid. The activation energy of the dominant surface process is evaluated to be 1.5 x 10 5 J mol - 1 . The silicon deposition by the gaseous by-product, trichlorosilane, is shown to have a negligible influence on the silicon etch rate

  8. Impact of pH on hydrogen oxidizing redox processes in aquifers due to gas intrusions

    Science.gov (United States)

    Metzgen, Adrian; Berta, Marton; Dethlefsen, Frank; Ebert, Markus; Dahmke, Andreas

    2017-04-01

    Hydrogen production from excess energy and its storage can help increasing the efficiency of solar and wind in the energy mix. Therefore, hydrogen needs large-scale intermediate storage independent of the intended later use as hydrogen gas or as reactant to produce methane in the Sabatier process. A possible storage solution is using the geological subsurface such as caverns built in salt deposits or aquifers that are not used for drinking water production. However, underground storage of hydrogen gas potentially leads to accidental gas leakages into near-surface potable aquifers triggering subsequent geochemical processes. These leakages pose potential risks that are currently not sufficiently understood. To close this gap in knowledge, a high-pressure laboratory column system was used to simulate a hydrogen gas intrusion into a shallow aquifer. Water and sediment were gained from a sandy Pleistocene aquifer near Neumünster, Germany. In the first stage of the experiment, 100% hydrogen gas was used to simulate dissolved hydrogen concentrations between 800 and 4000 µM by varying pH2 between 2 and 15 bars. pH values rose to between 7.9 and 10.4, partly due to stripping CO2 from the groundwater used during H2 gas addition. In a second stage, the pH was regulated in a range of 6.7 to 7.9 by using a gas mixture of 99% H2 and 1% CO2 at 5 bars of total gas pressure. Observed processes included hydrogen oxidation, sulfate reduction, acetogenesis, formate production, and methanogenesis, which were independent of the hydrogen concentration. Hydrogen oxidation and sulfate reduction showed zeroth order reaction rates and rate constants (106 to 412 µM/h and 12 to 33 µM/h, respectively) in the pH range between 8 and 10. At pH levels between 7 and 8, both reactions started out faster near the column's inflow but then seemed limited towards the columns outflow, suggesting the dependence of sulfate reduction on the pH-value. Acetogenesis dominated the pH range between 8 and 10

  9. Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

    NARCIS (Netherlands)

    Logan, B.E.; Call, D.; Cheng, S.; Hamelers, H.V.M.; Sleutels, T.H.J.A.; Jeremiasse, A.W.; Rozendal, R.A.

    2008-01-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few

  10. One-dimensional magnetohydrodynamic calculations of a hydrogen-gas puff

    International Nuclear Information System (INIS)

    Maxon, S.; Nielsen, P.D.

    1981-01-01

    A one-dimensional Lagrangian calculation of the implosion of a hydrogen gas puff is presented. At maximum compression, 60% of the mass is located in a density spike .5 mm off the axis with a half width of 40 μm. The temperature on axis reaches 200 eV

  11. Tritium assay in hydrogen gas by proportional counter with magnetic tape recording

    International Nuclear Information System (INIS)

    Grabczak, J.

    1982-03-01

    Analytical procedure is discussed concerning routine tritium activity determination in water samples based on hydrogen production from the water sample and radioactivity measurement by gas proportional counting. The method was found to be fully comparable to the widely adopted technique of liquid scintillation counting with electrolytic enrichment

  12. Development of a fermentation-based process for biomass conversion to hydrogen gas

    NARCIS (Netherlands)

    Claassen, P.A.M.; Vrije, de G.J.; Urbaniec, K.; Grabarczyk, R.

    2010-01-01

    The production of hydrogen gas from biomass to meet the foreseen demand arising from the expected introduction of fuel cells is envisaged. Apart from the well-known gasification method, fermentative conversion can also be applied for this purpose. Two options of the latter method, that is,

  13. Integration of phase change materials in compressed hydrogen gas systems: Modelling and parametric analysis

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rothuizen, Erasmus; Jørgensen, Jens-Erik

    2016-01-01

    to the phase change material, mainly occurs after the fueling is completed, resulting in a hydrogen peak temperature higher than 85 C and a lower fueled mass than a gas-cooled system. Such a mass reduction accounts for 12% with respect to the case of a standard tank system fueled at 40 C. A parametric analysis...

  14. Hydrogen Gas Recycling for Energy Efficient Ammonia Recovery in Electrochemical Systems

    NARCIS (Netherlands)

    Kuntke, Philipp; Rodríguez Arredondo, Mariana; Widyakristi, Laksminarastri; Heijne, ter Annemiek; Sleutels, Tom H.J.A.; Hamelers, Hubertus V.M.; Buisman, Cees J.N.

    2017-01-01

    Recycling of hydrogen gas (H2) produced at the cathode to the anode in an electrochemical system allows for energy efficient TAN (Total Ammonia Nitrogen) recovery. Using a H2 recycling electrochemical system (HRES) we achieved high TAN transport rates at low energy input. At

  15. Life Cycle Assessment of Hydrogen Production via Natural Gas Steam Reforming; TOPICAL

    International Nuclear Information System (INIS)

    Spath, P. L.; Mann, M. K.

    2000-01-01

    A life cycle assessment of hydrogen production via natural gas steam reforming was performed to examine the net emissions of greenhouse gases as well as other major environmental consequences. LCA is a systematic analytical method that helps identify and evaluate the environmental impacts of a specific process or competing processes

  16. Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

    Energy Technology Data Exchange (ETDEWEB)

    Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

    2011-09-01

    Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

  17. Carbon dioxide emission in hydrogen production technology from coke oven gas with life cycle approach

    Directory of Open Access Journals (Sweden)

    Burmistrz Piotr

    2016-01-01

    Full Text Available The analysis of Carbon Footprint (CF for technology of hydrogen production from cleaned coke oven gas was performed. On the basis of real data and simulation calculations of the production process of hydrogen from coke gas, emission indicators of carbon dioxide (CF were calculated. These indicators are associated with net production of electricity and thermal energy and direct emission of carbon dioxide throughout a whole product life cycle. Product life cycle includes: coal extraction and its transportation to a coking plant, the process of coking coal, purification and reforming of coke oven gas, carbon capture and storage. The values were related to 1 Mg of coking blend and to 1 Mg of the hydrogen produced. The calculation is based on the configuration of hydrogen production from coke oven gas for coking technology available on a commercial scale that uses a technology of coke dry quenching (CDQ. The calculations were made using ChemCAD v.6.0.2 simulator for a steady state of technological process. The analysis of carbon footprint was conducted in accordance with the Life Cycle Assessment (LCA.

  18. ASU nitrogen sweep gas in hydrogen separation membrane for production of HRSG duct burner fuel

    Science.gov (United States)

    Panuccio, Gregory J.; Raybold, Troy M.; Jamal, Agil; Drnevich, Raymond Francis

    2013-04-02

    The present invention relates to the use of low pressure N2 from an air separation unit (ASU) for use as a sweep gas in a hydrogen transport membrane (HTM) to increase syngas H2 recovery and make a near-atmospheric pressure (less than or equal to about 25 psia) fuel for supplemental firing in the heat recovery steam generator (HRSG) duct burner.

  19. Building and interconnecting hydrogen networks: Insights from the electricity and gas experience in Europe

    International Nuclear Information System (INIS)

    Bento, Nuno

    2008-01-01

    This paper aims to investigate the transition to a new energy system based on hydrogen in the European liberalized framework. After analyzing the literature on the hydrogen infrastructure needs in Europe, we estimate the size and scope of the transition challenge. We take the theoretical framework of network economics to analyze early hydrogen infrastructure needs. Therefore, several concepts are applied to hydrogen economics such as demand club effects, scale economies on large infrastructures, scope economies, and positive socio-economical externalities. Based on the examples of the electricity and natural gas industry formation in Europe, we argue for public intervention in order to create conditions to reach more rapidly the critical size of the network and to prompt network externalities, allowing for the market diffusion of and, thus, an effective transition to the new energy system

  20. Hydrogen combustion and exhaust emissions in a supercharged gas engine ignited with micro pilot diesel fuel

    Energy Technology Data Exchange (ETDEWEB)

    Tomita, E.; Kawahara, N. [Okayama Univ., Okayama (Japan); Roy, M.M. [Rajshahi Univ. of Engineering and Technology, Rajshahi (Bangladesh)

    2009-07-01

    A hydrogen combustion and exhaust emissions in a supercharged gas engine ignited with micro pilot diesel fuel was discussed in this presentation. A schematic diagram of the experimental study was first presented. The single cylinder, water-cooled, supercharged test engine was illustrated. Results were presented for the following: fuel energy and energy share (hydrogen and diesel fuel); pressure history and rate of heat release; engine performance and exhaust emissions; effect of nitrogen dilution on heat value per cycle; effect of N{sub 2} dilution on pressure history and rate of heat release; and engine performance and exhaust emissions. This presentation demonstrated that smooth and knock-free engine operation results from the use of hydrogen in a supercharged dual-fuel engine for leaner fuel-air equivalence ratios maintaining high thermal efficiency. It was possible to attain mor3 than 90 per cent hydrogen-energy substitution to the diesel fuel with zero smoke emissions. figs.

  1. Hydrogen combustion and exhaust emissions in a supercharged gas engine ignited with micro pilot diesel fuel

    International Nuclear Information System (INIS)

    Tomita, E.; Kawahara, N.; Roy, M.M.

    2009-01-01

    A hydrogen combustion and exhaust emissions in a supercharged gas engine ignited with micro pilot diesel fuel was discussed in this presentation. A schematic diagram of the experimental study was first presented. The single cylinder, water-cooled, supercharged test engine was illustrated. Results were presented for the following: fuel energy and energy share (hydrogen and diesel fuel); pressure history and rate of heat release; engine performance and exhaust emissions; effect of nitrogen dilution on heat value per cycle; effect of N 2 dilution on pressure history and rate of heat release; and engine performance and exhaust emissions. This presentation demonstrated that smooth and knock-free engine operation results from the use of hydrogen in a supercharged dual-fuel engine for leaner fuel-air equivalence ratios maintaining high thermal efficiency. It was possible to attain mor3 than 90 per cent hydrogen-energy substitution to the diesel fuel with zero smoke emissions. figs.

  2. Chromosomal changes in maize induced by hydrogen fluoride gas

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, A H

    1970-01-01

    Maize seedlings were fumigated in growth chambers with hydrogen fluoride at a concentration of about 3 ..mu..g/m/sup 3/. The experiment was run for 10 days, with the first group of treated plants removed from the chambers after 4 days and then at intervals of 2 days. Microsporocyte smears from the treated plants revealed chromosomal aberrations that included asynaptic regions, translocations, inversions, and bridges plus fragments or fragments by themselves. It is believed that these abnormalities were due to the physiological effect of HF causing the chromosomes to become sticky and/or to the occurrence of chromatid breakage followed by reunion to sticky and/or to the occurrence of chromatid breakage followed by reunion to form structural changes. These findings indicate that HF is a mutagenic agent.

  3. 12,000 l/sec cryopump for hydrogen gas

    International Nuclear Information System (INIS)

    Shibata, Takemasa; Matsuda, Shinzaburo; Shirakata, Hirofumi; Saito, Masaki; Mizuno, Masayasu.

    1978-08-01

    In the neutral beam injector of JT-60, cryogenic pumps with pumping rate 10 6 l/sec for hydrogen will be installed in the beam lines. To develop the cryopumps a small-scale pump of 12,000 l/sec was made and its fundamental pumping characteristics were measured. The cryogenic pump consists of liquid helium cooled panel, liquid nitrogen cooled chevron and radiation shields. The cryopanel is cylindrical form and the chevron is arranged concentrically within it. The measured pumping rate agrees with the design one. The pumping rate is not lowered by 30 Torr.l/cm 2 on the cryopanel. Liquid helium consumption rate was also measured and the pressure rise in the vacuum chamber in reactivation of the cryopanel was observed. (auth.)

  4. Large scale gas chromatographic demonstration system for hydrogen isotope separation

    International Nuclear Information System (INIS)

    Cheh, C.H.

    1988-01-01

    A large scale demonstration system was designed for a throughput of 3 mol/day equimolar mixture of H,D, and T. The demonstration system was assembled and an experimental program carried out. This project was funded by Kernforschungszentrum Karlsruhe, Canadian Fusion Fuel Technology Projects and Ontario Hydro Research Division. Several major design innovations were successfully implemented in the demonstration system and are discussed in detail. Many experiments were carried out in the demonstration system to study the performance of the system to separate hydrogen isotopes at high throughput. Various temperature programming schemes were tested, heart-cutting operation was evaluated, and very large (up to 138 NL/injection) samples were separated in the system. The results of the experiments showed that the specially designed column performed well as a chromatographic column and good separation could be achieved even when a 138 NL sample was injected

  5. On thermal conductivity of gas mixtures containing hydrogen

    Science.gov (United States)

    Zhukov, Victor P.; Pätz, Markus

    2017-06-01

    A brief review of formulas used for the thermal conductivity of gas mixtures in CFD simulations of rocket combustion chambers is carried out in the present work. In most cases, the transport properties of mixtures are calculated from the properties of individual components using special mixing rules. The analysis of different mixing rules starts from basic equations and ends by very complex semi-empirical expressions. The formulas for the thermal conductivity are taken for the analysis from the works on modelling of rocket combustion chambers. \\hbox {H}_2{-}\\hbox {O}_2 mixtures are chosen for the evaluation of the accuracy of the considered mixing rules. The analysis shows that two of them, of Mathur et al. (Mol Phys 12(6):569-579, 1967), and of Mason and Saxena (Phys Fluids 1(5):361-369, 1958), have better agreement with the experimental data than other equations for the thermal conductivity of multicomponent gas mixtures.

  6. Graphite selection for the PBMR reflector

    International Nuclear Information System (INIS)

    Marsden, B.J.; Preston, S.D.

    2000-01-01

    A high temperature, direct cycle gas turbine, graphite moderated, helium cooled, pebble-bed reactor (PBMR) is being designed and constructed in South Africa. One of the major components in the PBMR is the graphite reflector, which must be designed to last thirty-five full power years. Fast neutron irradiation changes the dimensions and material properties of reactor graphite, thus for design purposes a suitable graphite database is required. Data on the effect of irradiation on nuclear graphites has been gathered for many years, at considerable financial cost, but unfortunately these graphites are no longer available due to rationalization of the graphite industry and loss of key graphite coke supplies. However, it is possible, using un-irradiated graphite materials properties and knowledge of the particular graphite microstructure, to determine the probable irradiation behaviour. Three types of nuclear graphites are currently being considered for the PBMR reflector: an isostatically moulded, fine grained, high strength graphite and two extruded medium grained graphites of moderately high strength. Although there is some irradiation data available for these graphites, the data does not cover the temperature and dose range required for the PBMR. The available graphites have been examined to determine their microstructure and some of the key material properties are presented. (authors)

  7. Measurement of percent hydrogen in the mechanical vacuum pump gas stream during BWR startup

    International Nuclear Information System (INIS)

    Garcia, Susan E.; Odell, Andrew D.; Giannelli, Joseph F.

    2012-09-01

    All U.S BWRs use a Mechanical Vacuum Pump (MVP) to establish condenser vacuum during start-ups, normally from the initial heat-up to the point where sufficient reactor steam pressure and flow is available to place the Steam Jet Air Ejector (SJAE) and off-gas treatment system in service. MVP operation is restricted to <5% power and gas stream concentrations of <4% H 2 , the lower flammability limit (LFL) for hydrogen/air mixtures. For a particular plant startup prior to hydrogen injection for hydrogen water chemistry (HWC), the MVP %H 2 would depend on the air in-leakage rate, the H 2 gas generation rate from radiolysis and the gas/steam transport rate from the reactor vessel to the main condenser. The radiolysis rate at low power, which is not precisely known and has not been modeled for the BWR, is normally assumed to increase in proportion to thermal power. Two thirds of the radiolytic gas by volume would be H 2 and one third O 2 . The MVP is not equipped with %H 2 sampling and measurement capability, and many MVP systems include no flow measurement. No U.S plant or literature data on MVP %H 2 were found. The industry-first Early Hydrogen Water Chemistry (EHWC) demonstration at the Peach Bottom 3 nuclear power plant involved hydrogen gas injection into the reactor vessel during startup while the MVP was in service. To support the EHWC project, it was necessary to collect baseline MVP %H 2 data during a startup without hydrogen injection and to monitor MVP %H 2 during the startup with EHWC. The MVP system had no normal sample point, but included test taps in the suction and discharge piping. A sampling method and apparatus was invented (EPRI patent pending), designed, built and applied to obtain %H 2 measurements in the MVP gas stream. The apparatus allowed a gas sample stream to be taken from either the suction (vacuum) or discharge side of the MVP. The gas sample stream was preconditioned to remove moisture (the MVP uses water as a liquid compressant), flowed to

  8. Carbon-14 Graphitization Chemistry

    Science.gov (United States)

    Miller, James; Collon, Philippe; Laverne, Jay

    2014-09-01

    Accelerator Mass Spectrometry (AMS) is a process that allows for the analysis of mass of certain materials. It is a powerful process because it results in the ability to separate rare isotopes with very low abundances from a large background, which was previously impossible. Another advantage of AMS is that it only requires very small amounts of material for measurements. An important application of this process is radiocarbon dating because the rare 14C isotopes can be separated from the stable 14N background that is 10 to 13 orders of magnitude larger, and only small amounts of the old and fragile organic samples are necessary for measurement. Our group focuses on this radiocarbon dating through AMS. When performing AMS, the sample needs to be loaded into a cathode at the back of an ion source in order to produce a beam from the material to be analyzed. For carbon samples, the material must first be converted into graphite in order to be loaded into the cathode. My role in the group is to convert the organic substances into graphite. In order to graphitize the samples, a sample is first combusted to form carbon dioxide gas and then purified and reduced into the graphite form. After a couple weeks of research and with the help of various Physics professors, I developed a plan and began to construct the setup necessary to perform the graphitization. Once the apparatus is fully completed, the carbon samples will be graphitized and loaded into the AMS machine for analysis.

  9. Fuel hydrogen retention of tungsten and the reduction by inert gas glow discharges

    Energy Technology Data Exchange (ETDEWEB)

    Hino, T., E-mail: tomhino@qe.eng.hokudai.ac.jp [Laboratory of Plasma Physics and Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Yamauchi, Y.; Kimura, Y. [Laboratory of Plasma Physics and Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Nishimura, K. [National Institute for Fusion Science, Toki-shi, Gifu-ken 509-5292 (Japan); Ueda, Y. [Graduate School of Engineering, Osaka University, Suita-shi 565-0872 (Japan)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer The performances of inert gas glow discharges for reduction of fuel hydrogen retention in tungsten were systematically investigated. Black-Right-Pointing-Pointer For the tungsten with rough surface structure, the reduction of fuel hydrogen retention by inert gas discharges is quite small. Black-Right-Pointing-Pointer The deuterium glow discharge is quite useful to reduce the tritium retention in plasma facing walls in fusion reactor. Black-Right-Pointing-Pointer The wall baking with temperature higher than 700-800 K is also useful to reduce the tritium retention in plasma facing walls. - Abstract: Polycrystalline tungsten was exposed to deuterium glow discharge followed by He, Ne or Ar glow discharge. The amount of retained deuterium in the tungsten was measured using residual gas analysis. The amount of desorbed deuterium during the inert gas glow discharge was also measured. The amount of retained deuterium was 2-3 times larger compared with a case of stainless steel. The ratios of desorbed amount of deuterium by He, Ne and Ar glow discharges were 4.6, 3.1 and 2.9%, respectively. These values were one order of magnitude smaller compared with the case of stainless steel. The inert gas glow discharge is not suitable to reduce the fuel hydrogen retention for tungsten walls. However, the wall baking with a temperature higher than 700 K is suitable to reduce the fuel hydrogen retention. It is also shown that the use of deuterium glow discharge is effective to reduce the in-vessel tritium inventory in fusion reactors through the hydrogen isotope exchange.

  10. Exergy and thermoeconomic evaluation of hydrogen production from natural gas; Avaliacao exergetica e termo-economica da producao de hidrogenio a partir do gas natural

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Flavio Eduardo da [PROMON Engenharia Ltda., Sao Paulo, SP (Brazil); Oliveira Junior, Silvio de [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica

    2008-07-01

    Some specific processes are required to obtain pure hydrogen and the most usual one is the natural gas reforming, where natural gas reacts with superheated steam producing H{sub 2}, CO, CO{sub 2} and H{sub 2}O. This paper presents exergy and thermoeconomic analysis of a complete hydrogen production unit of a petroleum refinery. The hydrogen production unit analysed in this paper has to supply 550,000 Nm{sup 3} of hydrogen per day to purify diesel oil. Based on a synthesis plant of the hydrogen production unit, the exergy efficiency of each component and of the overall plant are calculated. The hydrogen production cost is determined by means of a thermoeconomic analysis in which the equality cost partition method is employed, including capital and operational costs, in order to determine the production cost of hydrogen and other products of the plant.(author)

  11. Verification and validation of the THYTAN code for the graphite oxidation analysis in the HTGR systems

    International Nuclear Information System (INIS)

    Shimazaki, Yosuke; Isaka, Kazuyoshi; Nomoto, Yasunobu; Seki, Tomokazu; Ohashi, Hirofumi

    2014-12-01

    The analytical models for the evaluation of graphite oxidation were implemented into the THYTAN code, which employs the mass balance and a node-link computational scheme to evaluate tritium behavior in the High Temperature Gas-cooled Reactor (HTGR) systems for hydrogen production, to analyze the graphite oxidation during the air or water ingress accidents in the HTGR systems. This report describes the analytical models of the THYTAN code in terms of the graphite oxidation analysis and its verification and validation (V and V) results. Mass transfer from the gas mixture in the coolant channel to the graphite surface, diffusion in the graphite, graphite oxidation by air or water, chemical reaction and release from the primary circuit to the containment vessel by a safety valve were modeled to calculate the mass balance in the graphite and the gas mixture in the coolant channel. The computed solutions using the THYTAN code for simple questions were compared to the analytical results by a hand calculation to verify the algorithms for each implemented analytical model. A representation of the graphite oxidation experimental was analyzed using the THYTAN code, and the results were compared to the experimental data and the computed solutions using the GRACE code, which was used for the safety analysis of the High Temperature Engineering Test Reactor (HTTR), in regard to corrosion depth of graphite and oxygen concentration at the outlet of the test section to validate the analytical models of the THYTAN code. The comparison of THYTAN code results with the analytical solutions, experimental data and the GRACE code results showed the good agreement. (author)

  12. Highly Sensitive and Selective Hydrogen Gas Sensor Using the Mesoporous SnO2 Modified Layers

    Directory of Open Access Journals (Sweden)

    Niuzi Xue

    2017-10-01

    Full Text Available It is important to improve the sensitivities and selectivities of metal oxide semiconductor (MOS gas sensors when they are used to monitor the state of hydrogen in aerospace industry and electronic field. In this paper, the ordered mesoporous SnO2 (m-SnO2 powders were prepared by sol-gel method, and the morphology and structure were characterized by X-ray diffraction analysis (XRD, transmission electron microscope (TEM and Brunauer–Emmett–Teller (BET. The gas sensors were fabricated using m-SnO2 as the modified layers on the surface of commercial SnO2 (c-SnO2 by screen printing technology, and tested for gas sensing towards ethanol, benzene and hydrogen with operating temperatures ranging from 200 °C to 400 °C. Higher sensitivity was achieved by using the modified m-SnO2 layers on the c-SnO2 gas sensor, and it was found that the S(c/m2 sensor exhibited the highest response (Ra/Rg = 22.2 to 1000 ppm hydrogen at 400 °C. In this paper, the mechanism of the sensitivity and selectivity improvement of the gas sensors is also discussed.

  13. Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

    Science.gov (United States)

    Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

    2017-07-01

    Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

  14. Hydrogen Addition for Improved Lean Burn Capability on Natural Gas Engine

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Tobias [Lund Inst. of Technology (Sweden). Dept. of Heat and Power Engineering

    2002-12-01

    Lean burn spark ignition (SI) engines powered by natural gas is an attractive alternative to the Diesel engine, especially in urban traffic, where reduction of tailpipe emissions are of great importance. A major benefit is the large reduction in soot (PM). Lean burn spark ignition (SI) engines yield high fuel conversion efficiency and also relatively low NO{sub x} emissions at full load. In order to improve the engine operating characteristics at lower loads, the {lambda}-value is normally reduced to some degree, with increased NO{sub x} emissions and reduced efficiency as a result. This is a drawback for the lean burn engines, especially in urban applications such as in city buses and distribution trucks for urban use. So, it is desirable to find ways to extend the lean limit at low loads. One way to improve these part load properties is to add hydrogen to the natural gas in order to improve the combustion characteristics of the fuel. It is possible to extend the lean limit of a natural gas engine by addition of hydrogen to the primary fuel. This report presents measurements made on a single cylinder 1.6 liter natural gas engine. Two combustion chambers, one slow and one fast burning, were tested with various amounts of hydrogen (0 to 20 %-vol) added to natural gas. Three operating conditions were investigated for each combustion chamber and each hydrogen content level; idle, wide open throttle (WOT) and a high load condition (simulated turbo charging). For all three operating conditions, the air/fuel ratio was varied between stoichiometric and the lean limit. For each operating point, the ignition timing was swept in order to find maximum brake torque (MBT) timing. In some cases were the ignition timing limited by knock. Heat release rate calculations were made in order to assess the influence of hydrogen addition on burn rate. Addition of hydrogen showed an increase in burn rate for both combustion chambers, resulting in more stable combustion close to the lean

  15. Massive Cerebral Gas Embolism under Discectomy due to Hydrogen Peroxide Irrigation

    Directory of Open Access Journals (Sweden)

    Junjie Zhang

    2015-01-01

    Full Text Available Massive cerebral and spinal gas embolism occurs rarely as a complication of discectomy. We report a 54-year-old female who had undergone a discectomy (L3/4 and L4/5 under epidural anesthesia in a local hospital developed multiple massive gas embolisms. At closure, surgeons irrigated the incision wound with hydrogen peroxide. Soon after the irrigation, the patient suddenly developed tachycardia, hypotension, and rapid oxygen desaturation. Subsequently, patient progressed into unconsciousness and right hemianopsia quadriplegia. Computed tomography (CT scan showed multiple hypointensity spots around the brain due to cerebral gas embolism, which indicated the pneumoencephalos. The likely mechanism was the absorption of hydrogen peroxide into blood. When the amount of oxygen evolved exceeded its maximal blood solubility, venous embolization occurred. Though the patient was treated with supportive treatments and hyperbaric oxygen, she did not get full recovery and was left with severe long-term cerebral injury.

  16. Low temperature catalytic combustion of natural gas - hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E; Roth, F von; Hottinger, P; Truong, T B [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The low temperature catalytic combustion of natural gas - air mixtures would allow the development of no-NO{sub x} burners for heating and power applications. Using commercially available catalysts, the room temperature ignition of methane-propane-air mixtures has been shown in laboratory reactors with combustion efficiencies over 95% and maximum temperatures less than 700{sup o}C. After a 500 hour stability test, severe deactivation of both methane and propane oxidation functions was observed. In cooperation with industrial partners, scaleup to 3 kW is being investigated together with startup dynamics and catalyst stability. (author) 3 figs., 3 refs.

  17. Characterisation of Chlorine Behavior in French Graphite

    International Nuclear Information System (INIS)

    Blondel, A.; Moncoffre, N.; Toulhoat, N.; Bererd, N.; Petit, L.; Laurent, G.; Lamouroux, C.

    2016-01-01

    Chlorine 36 is one of the main radionuclides of concern for French graphite waste disposal. In order to help the understanding of its leaching behaviour under disposal conditions, the respective impact of temperature, irradiation and gas radiolysis on chlorine release in reactor has been studied. Chlorine 36 has been simulated through chlorine 37 ion implantation in virgin nuclear graphite samples. Results show that part of chlorine is highly mobile in graphite in the range of French reactors operating temperatures in relation with graphite structural recovering. Ballistic damage generated by irradiation also promotes chlorine release whereas no clear impact of the coolant gas radiolysis was observed in the absence of graphite radiolytic corrosion. (author)

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

    International Nuclear Information System (INIS)

    Alcala Ruiz, F.

    1984-01-01

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

  19. Synchrotron X-Ray Study of Melting in Submonolayer Ar and other Rare-Gas Films on Graphite

    DEFF Research Database (Denmark)

    McTague, J. P.; Als-Nielsen, Jens Aage; Bohr, Jakob

    1982-01-01

    Synchrotron x-ray diffraction studies of the (10) peak of Ar on the (001) surface of ZYX graphite show a sharp but continuous broadening of the Bragg peak with increasing temperature. Below a coverage of ∼ 1 Ar atom per six surface carbon atoms (ρ=1) the onset of this transition occurs...

  20. Solid adsorbents for removal of hydrogen sulphide from hot gas

    Energy Technology Data Exchange (ETDEWEB)

    Furimsky, E.; Yumura, Motoo

    1986-04-01

    A wide range of solids have been tested as potential adsorbents for H/sub 2/S removal from hot gas. These solids can be divided into two main groups, i.e., the adsorbents containing alkaline earth metals and those containing transition metals. Among the former, calcium oxide and naturally occurring materials such as limestone, dolomite and calcium silicate have attracted a great deal of attention. The adsorbents of the second group include iron oxide alone or in combination with some supports, zinc oxide, zinc ferrite and manganese oxide. The materials containing both the alkaline earth metals and transition metals, e.g., manganese nodules, fly ash and the reject from the aluminium industry (red mud) have been evaluated as well.

  1. Hydrogen separation from coke oven gas using PSA

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, M.: Tanibashi, N.; Nishida, S

    1983-01-01

    Twin column apparatus was used to study the adsorption characteristics of various components of coke oven gas at an adsorption pressure of 5 kg/cm/SUP/2G. The following results were obtained. Over 99.99% Of the H/sub 2/ could be separated, and for this a 5 angstrom zeolite was optimal. Since the break-through order is H/sub 2/, O/sub 2/, N/sub 2/, CH/SUB/4, CO there is a tendency for the product H/sub 2/ to be adulterated with O/sub 2/ and N/sub 2/. Although there was a large adsorption of CO/sub 2/ and C/sub 2/H/sub 4/, desorption was difficult, even under reduced pressure and H/sub 2/ flushing. Hence, the industrial version of this apparatus will have to include activated carbon. 5 references.

  2. Experimental study on the natural gas dual fuel engine test and the higher the mixture ratio of hydrogen to natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Kim, B.S.; Lee, Y.S.; Park, C.K. [Cheonnam University, Kwangju (Korea); Masahiro, S. [Kyoto University, Kyoto (Japan)

    1999-05-28

    One of the unsolved problems of the natural gas dual fuel engine is that there is too much exhaust of Total Hydrogen Carbon(THC) at a low equivalent mixture ratio. To fix it, a natural gas mixed with hydrogen was applied to engine test. The results showed that the higher the mixture ratio of hydrogen to natural gas, the higher the combustion efficiency. And when the amount of the intake air is reached to 90% of WOT, the combustion efficiency was promoted. But, like a case making the injection timing earlier, the equivalent mixture ratio for the nocking limit decreases and the produce of NOx increases. 5 refs., 9 figs., 1 tab.

  3. A Nose for Hydrogen Gas: Fast, Sensitive H2 Sensors Using Electrodeposited Nanomaterials.

    Science.gov (United States)

    Penner, Reginald M

    2017-08-15

    Hydrogen gas (H 2 ) is odorless and flammable at concentrations above 4% (v/v) in air. Sensors capable of detecting it rapidly at lower concentrations are needed to "sniff" for leaked H 2 wherever it is used. Electrical H 2 sensors are attractive because of their simplicity and low cost: Such sensors consist of a metal (usually palladium, Pd) resistor. Exposure to H 2 causes a resistance increase, as Pd metal is converted into more resistive palladium hydride (PdH x ). Sensors based upon Pd alloy films, developed in the early 1990s, were both too slow and too insensitive to meet the requirements of H 2 safety sensing. In this Account, we describe the development of H 2 sensors that are based upon electrodeposited nanomaterials. This story begins with the rise to prominence of nanowire-based sensors in 2001 and our demonstration that year of the first nanowire-based H 2 sensor. The Pd nanowires used in these experiments were prepared by electrodepositing Pd at linear step-edge defects on a graphite electrode surface. In 2005, lithographically patterned nanowire electrodeposition (LPNE) provided the capability to pattern single Pd nanowires on dielectrics using electrodeposition. LPNE also provided control over the nanowire thickness (±1 nm) and width (±10-15%). Using single Pd nanowires, it was demonstrated in 2010 that smaller nanowires responded more rapidly to H 2 exposure. Heating the nanowire using Joule self-heating (2010) also dramatically accelerated sensor response and recovery, leading to the conclusion that thermally activated H 2 chemisorption and desorption of H 2 were rate-limiting steps in sensor response to and recovery from H 2 exposure. Platinum (Pt) nanowires, studied in 2012, showed an inverted resistance response to H 2 exposure, that is, the resistance of Pt nanowires decreased instead of increased upon H 2 exposure. H 2 dissociatively chemisorbs at a Pt surface to form Pt-H, but in contrast to Pd, it stays on the Pt surface. Pt nanowires

  4. Modelling of fast hydrogen permeability of alloys for membrane gas separation

    Science.gov (United States)

    Zaika, Yu. V.; Rodchenkova, N. I.

    2017-05-01

    The method of measuring the specific hydrogen permeability is used to study various alloys that are promising for gas separation installations. The nonlinear boundary value problem of hydrogen permeability complying with the specific features of the experiment and its modifications taking into account the high transfer rate is presented. Substantial difference from the quasi-equilibrium model (Richardson approximation in the assumption of the equilibrium Sieverts' law near the surface) has been discussed. The model is tested on published experimental data on Ta77Nb23 alloy.

  5. Robust, Reliable Low Emission Gas Turbine Combustion of High Hydrogen Content Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Wooldridge, Margaret Stacy [Univ. of Michigan, Ann Arbor, MI (United States); Im, Hong Geum [Univ. of Michigan, Ann Arbor, MI (United States)

    2016-12-16

    The effects of high hydrogen content fuels were studied using experimental, computational and theoretical approaches to understand the effects of mixture and state conditions on the ignition behavior of the fuels. A rapid compression facility (RCF) was used to measure the ignition delay time of hydrogen and carbon monoxide mixtures. The data were combined with results of previous studies to develop ignition regime criteria. Analytical theory and direct numerical simulation were used to validate and interpret the RCF ignition data. Based on the integrated information the ignition regime criteria were extended to non-dimensional metrics which enable application of the results to practical gas turbine combustion systems.

  6. Hydrogen gas inhalation inhibits progression to the "irreversible" stage of shock after severe hemorrhage in rats.

    Science.gov (United States)

    Matsuoka, Tadashi; Suzuki, Masaru; Sano, Motoaki; Hayashida, Kei; Tamura, Tomoyoshi; Homma, Koichiro; Fukuda, Keiichi; Sasaki, Junichi

    2017-09-01

    Mortality of hemorrhagic shock primarily depends on whether or not the patients can endure the loss of circulating volume until radical treatment is applied. We investigated whether hydrogen (H2) gas inhalation would influence the tolerance to hemorrhagic shock and improve survival. Hemorrhagic shock was achieved by withdrawing blood until the mean arterial blood pressure reached 30-35 mm Hg. After 60 minutes of shock, the rats were resuscitated with a volume of normal saline equal to four times the volume of shed blood. The rats were assigned to either the H2 gas (1.3% H2, 26% O2, 72.7% N2)-treated group or the control gas (26% O2, 74% N2)-treated group. Inhalation of the specified gas mixture began at the initiation of blood withdrawal and continued for 2 hours after fluid resuscitation. The survival rate at 6 hours after fluid resuscitation was 80% in H2 gas-treated rats and 30% in control gas-treated rats (p gas-treated rats than in the control rats. Despite losing more blood, the increase in serum potassium levels was suppressed in the H2 gas-treated rats after 60 minutes of shock. Fluid resuscitation completely restored blood pressure in the H2 gas-treated rats, whereas it failed to fully restore the blood pressure in the control gas-treated rats. At 2 hours after fluid resuscitation, blood pressure remained in the normal range and metabolic acidosis was well compensated in the H2 gas-treated rats, whereas we observed decreased blood pressure and uncompensated metabolic acidosis and hyperkalemia in the surviving control gas-treated rats. H2 gas inhalation delays the progression to irreversible shock. Clinically, H2 gas inhalation is expected to stabilize the subject until curative treatment can be performed, thereby increasing the probability of survival after hemorrhagic shock.

  7. Hydrogen amplification of coke oven gas by reforming of methane in a ceramic membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuwen; Li, Qian; Shen, Peijun; Liu, Yong; Yang, Zhibin; Ding, Weizhong; Lu, Xionggang [School of Material Science and Engineering, Shanghai University, No. 275 Mail Box, 149 Yanchang Road, Shanghai 200072 (China)

    2008-07-15

    To maximize hydrogen production from coke oven gas (COG), partial oxidation of methane in COG was studied thermodynamically and experimentally. Thermodynamic analysis indicates that an optimal hydrogen yield of 1.04-1.10 mole per mole of the consumed COG can be achieved when the initial ratio of O{sub 2} and CH{sub 4} is 0.57-0.46 in a temperature range of 800-900 C, and the corresponding amplification of original hydrogen in COG reaches 1.8-1.9 times. The amplification of original hydrogen was carried out in a BaCo{sub 0.7}Fe{sub 0.2}Nb{sub 0.1}O{sub 3-{delta}} (BCFNO) membrane reactor, and the hydrogen yield in the lab scale was about 80% more than that of original H{sub 2} in model COG. In a large hydrogen content in COG, the ceramic membrane reactors made from perovskite mixed-conducting oxygen-permeable materials must have higher stability to withstand the harsh reduction condition. (author)

  8. Research and development program of hydrogen production system with high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Miyamoto, Y.; Shiozawa, S.; Ogawa, M.; Inagaki, Y.; Nishihara, T.; Shimizu, S.

    2000-01-01

    Japan Atomic Energy Research Institute (JAERI) has been developing a hydrogen production system with a high temperature gas-cooled reactor (HTGR). While the HTGR hydrogen production system has the following advantages compared with a fossil-fired hydrogen production system; low operation cost (economical fuel cost), low CO 2 emission and saving of fossil fuel by use of nuclear heat, it requires some items to be solved as follows; cost reduction of facility such as a reactor, coolant circulation system and so on, development of control and safety technologies. As for the control and safety technologies, JAERI plans demonstration test with hydrogen production system by steam reforming of methane coupling to 30 Wt HTGR, named high temperature engineering test reactor (HTTR). Prior to the demonstration test, a 1/30-scale out-of-pile test facility is in construction for safety review and detailed design of the HTTR hydrogen production system. Also, design study will start for reduction of facility cost. Moreover, basic study on hydrogen production process without CO 2 emission is in progress by thermochemical water splitting. (orig.)

  9. Inactivation of animal and human prions by hydrogen peroxide gas plasma sterilization.

    Science.gov (United States)

    Rogez-Kreuz, C; Yousfi, R; Soufflet, C; Quadrio, I; Yan, Z-X; Huyot, V; Aubenque, C; Destrez, P; Roth, K; Roberts, C; Favero, M; Clayette, P

    2009-08-01

    Prions cause various transmissible spongiform encephalopathies. They are highly resistant to the chemical and physical decontamination and sterilization procedures routinely used in healthcare facilities. The decontamination procedures recommended for the inactivation of prions are often incompatible with the materials used in medical devices. In this study, we evaluated the use of low-temperature hydrogen peroxide gas plasma sterilization systems and other instrument-processing procedures for inactivating human and animal prions. We provide new data concerning the efficacy of hydrogen peroxide against prions from in vitro or in vivo tests, focusing on the following: the efficiency of hydrogen peroxide sterilization and possible interactions with enzymatic or alkaline detergents, differences in the efficiency of this treatment against different prion strains, and the influence of contaminating lipids. We found that gaseous hydrogen peroxide decreased the infectivity of prions and/or the level of the protease-resistant form of the prion protein on different surface materials. However, the efficiency of this treatment depended strongly on the concentration of hydrogen peroxide and the delivery system used in medical devices, because these effects were more pronounced for the new generation of Sterrad technology. The Sterrad NX sterilizer is 100% efficient (0% transmission and no protease-resistant form of the prion protein signal detected on the surface of the material for the mouse-adapted bovine spongiform encephalopathy 6PB1 strain and a variant Creutzfeldt-Jakob disease strain). Thus, gaseous or vaporized hydrogen peroxide efficiently inactivates prions on the surfaces of medical devices.

  10. Silicon surface damage caused by reactive ion etching in fluorocarbon gas mixtures containing hydrogen

    International Nuclear Information System (INIS)

    Norstroem, H.; Blom, H.; Ostling, M.; Nylandsted Larsen, A.; Keinonen, J.; Berg, S.

    1991-01-01

    For selective etching of SiO 2 on silicon, gases or gas mixtures containing hydrogen are often used. Hydrogen from the glow discharge promotes the formation of a thin film polymer layer responsible for the selectivity of the etching process. The reactive ion etch (RIE) process is known to create damage in the silicon substrate. The influence of hydrogen on the damage and deactivation of dopants is investigated in the present work. The distribution of hydrogen in silicon, after different etching and annealing conditions have been studied. The influence of the RIE process on the charge carrier concentration in silicon has been investigated. Various analytical techniques like contact resistivity measurements, four point probe measurements, and Hall measurements have been used to determine the influence of the RIE process on the electrical properties of processed silicon wafers. The hydrogen profile in as-etched and post annealed wafers was determined by the 1 H( 15 N,αγ) 12 C nuclear reaction. The depth of the deactivated surface layer is discussed in terms of the impinging hydrogen ion energy, i.e., the possibility of H + ions to pick up an energy equal to the peak-to-peak voltage of the rf signal

  11. Palladium Gate All Around - Hetero Dielectric -Tunnel FET based highly sensitive Hydrogen Gas Sensor

    Science.gov (United States)

    Madan, Jaya; Chaujar, Rishu

    2016-12-01

    The paper presents a novel highly sensitive Hetero-Dielectric-Gate All Around Tunneling FET (HD-GAA-TFET) based Hydrogen Gas Sensor, incorporating the advantages of band to band tunneling (BTBT) mechanism. Here, the Palladium supported silicon dioxide is used as a sensing media and sensing relies on the interaction of hydrogen with Palladium-SiO2-Si. The high surface to volume ratio in the case of cylindrical GAA structure enhances the fortuities for surface reactions between H2 gas and Pd, and thus improves the sensitivity and stability of the sensor. Behaviour of the sensor in presence of hydrogen and at elevated temperatures is discussed. The conduction path of the sensor which is dependent on sensors radius has also been varied for the optimized sensitivity and static performance analysis of the sensor where the proposed design exhibits a superior performance in terms of threshold voltage, subthreshold swing, and band to band tunneling rate. Stability of the sensor with respect to temperature affectability has also been studied, and it is found that the device is reasonably stable and highly sensitive over the bearable temperature range. The successful utilization of HD-GAA-TFET in gas sensors may open a new door for the development of novel nanostructure gas sensing devices.

  12. Hydrogen Gas Inhalation Attenuates Seawater Instillation-Induced Acute Lung Injury via the Nrf2 Pathway in Rabbits.

    Science.gov (United States)

    Diao, Mengyuan; Zhang, Sheng; Wu, Lifeng; Huan, Le; Huang, Fenglou; Cui, Yunliang; Lin, Zhaofen

    2016-12-01

    Seawater instillation-induced acute lung injury involves oxidative stress and apoptosis. Although hydrogen gas inhalation is reportedly protective in multiple types of lung injury, the effect of hydrogen gas inhalation on seawater instillation-induced acute lung injury remains unknown. This study investigated the effect of hydrogen gas on seawater instillation-induced acute lung injury and explored the mechanisms involved. Rabbits were randomly assigned to control, hydrogen (2 % hydrogen gas inhalation), seawater (3 mL/kg seawater instillation), and seawater + hydrogen (3 mL/kg seawater instillation + 2 % hydrogen gas inhalation) groups. Arterial partial oxygen pressure and lung wet/dry weight ratio were detected. Protein content in bronchoalveolar lavage fluid (BALF) and serum as well as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 levels were determined. Hematoxylin-eosin staining was used to monitor changes in lung specimens, and malondialdehyde (MDA) content and myeloperoxidase (MPO) activity were assayed. In addition, NF-E2-related factor (Nrf) 2 and heme oxygenase (HO)-1 mRNA and protein expression were measured, and apoptosis was assessed by measuring caspase-3 expression and using terminal deoxy-nucleotidyl transferase dUTP nick end-labeling (TUNEL) staining. Hydrogen gas inhalation markedly improved lung endothelial permeability and decreased both MDA content and MPO activity in lung tissue; these changes were associated with decreases in TNF-α, IL-1β, and IL-6 in BALF. Hydrogen gas also alleviated histopathological changes and cell apoptosis. Moreover, Nrf2 and HO-1 expressions were significantly activated and caspase-3 expression was inhibited. These results demonstrate that hydrogen gas inhalation attenuates seawater instillation-induced acute lung injury in rabbits and that the protective effects observed may be related to the activation of the Nrf2 pathway.

  13. Management of UKAEA graphite liabilities

    International Nuclear Information System (INIS)

    Wise, M.

    2001-01-01

    The UK Atomic Energy Authority (UKAEA) is responsible for managing its liabilities for redundant research reactors and other active facilities concerned with the development of the UK nuclear technology programme since 1947. These liabilities include irradiated graphite from a variety of different sources including low irradiation temperature reactor graphite (the Windscale Piles 1 and 2, British Energy Pile O and Graphite Low Energy Experimental Pile at Harwell and the Material Testing Reactors at Harwell and Dounreay), advanced gas-cooled reactor graphite (from the Windscale Advanced Gas-cooled Reactor) and graphite from fast reactor systems (neutron shield graphite from the Dounreay Prototype Fast Reactor and Dounreay Fast Reactor). The decommissioning and dismantling of these facilities will give rise to over 6,000 tonnes of graphite requiring disposal. The first graphite will be retrieved from the dismantling of Windscale Pile 1 and the Windscale Advanced Gas-cooled Reactor during the next five years. UKAEA has undertaken extensive studies to consider the best practicable options for disposing of these graphite liabilities in a manner that is safe whilst minimising the associated costs and technical risks. These options include (but are not limited to), disposal as Low Level Waste, incineration, or encapsulation and disposal as Intermediate Level Waste. There are a number of technical issues associated with each of these proposed disposal options; these include Wigner energy, radionuclide inventory determination, encapsulation of graphite dust, galvanic coupling interactions enhancing the corrosion of mild steel and public acceptability. UKAEA is currently developing packaging concepts and designing packaging plants for processing these graphite wastes in consultation with other holders of graphite wastes throughout Europe. 'Letters of Comfort' have been sought from both the Low Level Waste and the Intermediate Level Waste disposal organisations to support the

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-15

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

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

    International Nuclear Information System (INIS)

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

    1980-01-01

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

  16. Determining air quality and greenhouse gas impacts of hydrogen infrastructure and fuel cell vehicles.

    Science.gov (United States)

    Stephens-Romero, Shane; Carreras-Sospedra, Marc; Brouwer, Jacob; Dabdub, Donald; Samuelsen, Scott

    2009-12-01

    Adoption of hydrogen infrastructure and hydrogen fuel cell vehicles (HFCVs) to replace gasoline internal combustion engine (ICE) vehicles has been proposed as a strategy to reduce criteria pollutant and greenhouse gas (GHG) emissions from the transportation sector and transition to fuel independence. However, it is uncertain (1) to what degree the reduction in criteria pollutants will impact urban air quality, and (2) how the reductions in pollutant emissions and concomitant urban air quality impacts compare to ultralow emission gasoline-powered vehicles projected for a future year (e.g., 2060). To address these questions, the present study introduces a "spatially and temporally resolved energy and environment tool" (STREET) to characterize the pollutant and GHG emissions associated with a comprehensive hydrogen supply infrastructure and HFCVs at a high level of geographic and temporal resolution. To demonstrate the utility of STREET, two spatially and temporally resolved scenarios for hydrogen infrastructure are evaluated in a prototypical urban airshed (the South Coast Air Basin of California) using geographic information systems (GIS) data. The well-to-wheels (WTW) GHG emissions are quantified and the air quality is established using a detailed atmospheric chemistry and transport model followed by a comparison to a future gasoline scenario comprised of advanced ICE vehicles. One hydrogen scenario includes more renewable primary energy sources for hydrogen generation and the other includes more fossil fuel sources. The two scenarios encompass a variety of hydrogen generation, distribution, and fueling strategies. GHG emissions reductions range from 61 to 68% for both hydrogen scenarios in parallel with substantial improvements in urban air quality (e.g., reductions of 10 ppb in peak 8-h-averaged ozone and 6 mug/m(3) in 24-h-averaged particulate matter concentrations, particularly in regions of the airshed where concentrations are highest for the gasoline scenario).

  17. Effectiveness of oxygen enriched hydrogen-HHO gas addition on DI diesel engine performance, emission and combustion characteristics

    Directory of Open Access Journals (Sweden)

    Premkartikkumar S.R.

    2014-01-01

    Full Text Available Nowadays, more researches focus on protecting the environment. Present investigation concern with the effectiveness of Oxygen Enriched hydrogen- HHO gas addition on performance, emission and combustion characteristics of a DI diesel engine. Here the Oxygen Enriched hydrogen-HHO gas was produced by the process of water electrolysis. When potential difference is applied across the anode and cathode electrodes of the electrolyzer, water is transmuted into Oxygen Enriched hydrogen-HHO gas. The produced gas was aspirated into the cylinder along with intake air at the flow rates of 1 lpm and 3.3 lpm. The results show that when Oxygen Enriched hydrogen-HHO gas was inducted, the brake thermal efficiency of the engine increased by 11.06%, Carbon monoxide decreased by 15.38%, Unburned hydrocarbon decreased by 18.18%, Carbon dioxide increased by 6.06%, however, the NOX emission increased by 11.19%.

  18. Artificial graphites

    International Nuclear Information System (INIS)

    Maire, J.

    1984-01-01

    Artificial graphites are obtained by agglomeration of carbon powders with an organic binder, then by carbonisation at 1000 0 C and graphitization at 2800 0 C. After description of the processes and products, we show how the properties of the various materials lead to the various uses. Using graphite enables us to solve some problems, but it is not sufficient to satisfy all the need of the application. New carbonaceous material open application range. Finally, if some products are becoming obsolete, other ones are being developed in new applications [fr

  19. Electricity and gas market design to supply the German transport sector with hydrogen

    International Nuclear Information System (INIS)

    Robinius, Martin

    2015-01-01

    The German government has set targets to reduce greenhouse gas emissions by 40% by 2020, 55% by 2030, 70% by 2040 and 80-95% by 2050 compared to 1990 as reference year. As well as meeting other requirements, these targets can be achieved by raising the contribution of renewably-generated power to Germany's gross electricity consumption to 80% by 2050. Based on Germany's potential, intermittent energy sources (IES) such as on- and offshore wind, as well as photovoltaics, are necessary sources that must be utilized in order to achieve these ambitious targets. Because of the intermittency of these sources, there will be times in which surplus power generated could be used for example for the transport sector. During these periods of surplus power, the storage capacity of hydrogen allows for a socalled ''power-to-gas'' concept whereby the surplus power can be used to produce hydrogen and oxygen by means of electrolyzers. The aim of this thesis is to identify and develop a market design that is characterized by high penetration levels of IES, supplemented by the use of hydrogen in the transport sector. Furthermore, the aim was to develop a model in which the electricity and gas sector, including a hydrogen pipeline grid, is represented so as to analyze and validate selected market designs. Therefore, potential electricity and gas markets, as well as the most important potential share and stakeholders of a hydrogen infrastructure, are analyzed. With the model developed in this thesis, an existing energy concept has been developed, analyzed and evaluated. In addition, the distribution of the hydrogen production costs was calculated by employing a Monte Carlo Simulation analysis. The developed energy concept relies on 170 GW onshore and 60 GW offshore wind capacity and these dominate the model. This leads to surplus power, especially in the federal states of Lower Saxony, Schleswig-Holstein and Mecklenburg-Western Pomerania. To supply the

  20. Hydrogen storage materials discovery via high throughput ball milling and gas sorption.

    Science.gov (United States)

    Li, Bin; Kaye, Steven S; Riley, Conor; Greenberg, Doron; Galang, Daniel; Bailey, Mark S

    2012-06-11

    The lack of a high capacity hydrogen storage material is a major barrier to the implementation of the hydrogen economy. To accelerate discovery of such materials, we have developed a high-throughput workflow for screening of hydrogen storage materials in which candidate materials are synthesized and characterized via highly parallel ball mills and volumetric gas sorption instruments, respectively. The workflow was used to identify mixed imides with significantly enhanced absorption rates relative to Li2Mg(NH)2. The most promising material, 2LiNH2:MgH2 + 5 atom % LiBH4 + 0.5 atom % La, exhibits the best balance of absorption rate, capacity, and cycle-life, absorbing >4 wt % H2 in 1 h at 120 °C after 11 absorption-desorption cycles.

  1. Non-catalytic plasma-arc reforming of natural gas with carbon dioxide as the oxidizing agent for the production of synthesis gas or hydrogen

    OpenAIRE

    Blom, P.W.E.; Basson, G.W.

    2013-01-01

    The world’s energy consumption is increasing constantly due to the growing population of the world. The increasing energy consumption has a negative effect on the fossil fuel reserves of the world. Hydrogen has the potential to provide energy for all our needs by making use of fossil fuel such as natural gas and nuclear-based electricity. Hydrogen can be produced by reforming methane with carbon dioxide as the oxidizing agent. Hydrogen can be produced in a Plasma-arc reforming ...

  2. Visualization of hydrogen gas evolution during deformation and fracture in SCM 440 steel with different tempering conditions

    Energy Technology Data Exchange (ETDEWEB)

    Horikawa, Keitaro, E-mail: horikawa@me.es.osaka-u.ac.jp [Department of Mechanical Science and Bioengineering, School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Ando, Nobuaki; Kobayashi, Hidetoshi [Department of Mechanical Science and Bioengineering, School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Urushihara, Wataru [Surface Design and Corrosion Research Section, Materials Research Laboratory, Kobe Steel, Ltd., Kobe 651-2271 (Japan)

    2012-02-01

    Highlights: Black-Right-Pointing-Pointer We visualize emission sites of hydrogen atoms on the microstructures during deformation. Black-Right-Pointing-Pointer Hydrogen atoms are emitted from slip lines and inclusions when deformed. Black-Right-Pointing-Pointer We show the sequence of hydrogen gas evolution during deformation. Black-Right-Pointing-Pointer Hydrogen evolution amount will increase if the steels with high strength are tested. - Abstract: In the present study, the hydrogen gas evolution behavior was investigated in SCM 440 steel by using a hydrogen microprint technique (HMT) and a testing machine equipped with a quadrupole mass spectrometer (QMS) in a ultrahigh vacuum (UHV) atmosphere. SCM 440 steels prepared by varying the tempering temperature over the range 200-700 Degree-Sign C were evaluated in order to elucidate the relationship between the hydrogen gas evolution and the tempered microstructures in the deformation. Cathodic hydrogen charging was carried out with a current density of 100 A/m{sup 2} for 1 h at room temperature. For comparison, a tensile specimen was prepared without hydrogen charging. The HMT showed that silver particles, which are indicative of the hydrogen emission sites, were present mainly in the matrix as well as on the slip lines after the deformation. It is believed that the silver particles on the slip lines represent the effect of hydrogen transportation due to mobile dislocations. In addition, accumulation of silver particles around non-metallic inclusions such as Al{sub 2}O{sub 3} was also identified. This tendency was observed for different tempering conditions. From the relationship between the stress-strain curves and the hydrogen evolution, determined by using QMS under a UHV atmosphere, it was found that the hydrogen gas evolution behavior varied with the deformation stage.

  3. Visualization of hydrogen gas evolution during deformation and fracture in SCM 440 steel with different tempering conditions

    International Nuclear Information System (INIS)

    Horikawa, Keitaro; Ando, Nobuaki; Kobayashi, Hidetoshi; Urushihara, Wataru

    2012-01-01

    Highlights: ► We visualize emission sites of hydrogen atoms on the microstructures during deformation. ► Hydrogen atoms are emitted from slip lines and inclusions when deformed. ► We show the sequence of hydrogen gas evolution during deformation. ► Hydrogen evolution amount will increase if the steels with high strength are tested. - Abstract: In the present study, the hydrogen gas evolution behavior was investigated in SCM 440 steel by using a hydrogen microprint technique (HMT) and a testing machine equipped with a quadrupole mass spectrometer (QMS) in a ultrahigh vacuum (UHV) atmosphere. SCM 440 steels prepared by varying the tempering temperature over the range 200–700 °C were evaluated in order to elucidate the relationship between the hydrogen gas evolution and the tempered microstructures in the deformation. Cathodic hydrogen charging was carried out with a current density of 100 A/m 2 for 1 h at room temperature. For comparison, a tensile specimen was prepared without hydrogen charging. The HMT showed that silver particles, which are indicative of the hydrogen emission sites, were present mainly in the matrix as well as on the slip lines after the deformation. It is believed that the silver particles on the slip lines represent the effect of hydrogen transportation due to mobile dislocations. In addition, accumulation of silver particles around non-metallic inclusions such as Al 2 O 3 was also identified. This tendency was observed for different tempering conditions. From the relationship between the stress–strain curves and the hydrogen evolution, determined by using QMS under a UHV atmosphere, it was found that the hydrogen gas evolution behavior varied with the deformation stage.

  4. Some experiments on cold fusion by deuterium hydrogen gas infusion in titanium metal alloy

    International Nuclear Information System (INIS)

    Mestnik Filho, J.; Geraldo, L.P.; Pugliese, R.; Saxena, R.N.; Morato, S.P.; Fulfaro, R.

    1990-05-01

    New results on cold fusion are reported where three different experimental situations have been tried: a) deuterium gas loaded titanium; b) deuterium gas loaded Ti 0.8 Zr 0.2 CrMn alloy and c) titanium and the Ti 0.8 Zr 0.2 CrMn alloy loaded with a mixture of deuterium and hydrogen gases. With these experiments, new thermodynamical non equilibrium conditions were achieved and the possibility of cold fusion between protons and deuterons was also tested. Three independent neutron detectors and one NaI(Tl) were utilized. Despite some large values reported in the literature for the fusion rate, an upper limit of only 8 x 10 -24 fusions/sper deuterium pair or per deuterium-hydrogen pair was determined within the attained accuracy. (author) [pt

  5. Development of a Hydrogen Gas Sensor Using a Double Saw Resonator System at Room Temperature

    Directory of Open Access Journals (Sweden)

    Zainab Yunusa

    2015-02-01

    Full Text Available A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%.

  6. Population inversion in a recombining hydrogen plasma interacting with a helium gas

    International Nuclear Information System (INIS)

    Oda, Toshiatsu; Furukane, Utaro.

    1984-08-01

    A numerical investigation has shown that the population inversion between the levels with the principal quantum number i=2 and 3 takes place in a recombining hydrogen plasma which is interacting with a cool and dense helium gas on the basis of a collisional- radiative (CR) model. Overpopulation density Δn 32 , which is defined as the difference between the population densities per unit statistical weight of the upper and lower excited levels 3 and 2, is found to be much higher than a threshold level for the laser oscillation in the quasi-steady state when the hydrogen plasma with nsub(e) = 10 13 --10 14 cm -3 interacts with the helium gas with pressure of --50 Torr. (author)

  7. Membrane reforming in converting natural gas to hydrogen: Production costs, Part II

    Energy Technology Data Exchange (ETDEWEB)

    Iaquaniello, G; Cosenza, S [Technip-KTI S.p.A., via Castello della Magliana 75, Rome (Italy); Giacobbe, F; Morico, B; Farace, A [Processi Innovativi s.r.l., L' Aquila (Italy)

    2008-11-15

    This paper evaluates the production costs of a hybrid system based on a new membrane reforming MRR concept to convert natural gas to hydrogen and electricity. Membrane reforming with hydrogen-selective, palladium-silver membranes pushes the chemical equilibrium and allows higher methane conversions at lower temperature such as 650 C. The new MRR concept formed of a series of modules is put forward herein. Each module is made up of a reforming step and an external membrane separation unit. The estimates, based on utilities costs of a typical Italian refinery (end of 2006), show that the production costs for the hybrid system are 30% less than conventional tubular steam reforming technology, and 13% less than a gas-fired cogeneration plant coupled with a conventional H{sub 2} plant. (author)

  8. Chromatographic measurement of hydrogen isotopic and permanent gas impurities in tritium

    International Nuclear Information System (INIS)

    Warner, D.K.; Kinard, C.; Bohl, D.C.

    1976-01-01

    This paper describes a gas chromatograph that was designed for dedicated analysis of hydrogen isotopic and permanent gas impurities in tritium and tritium-deuterium mixtures. The instrument that was developed substantially improved the accuracy and precision of hydrogen isotopic analysis in the 20 ppM to one mole percent range as compared with other analytical methods. Several unique design features of the instrument were required due to the radiation and isotopic exchange properties of the tritium in the samples; descriptions of these features are presented along with details of the complete chromatographic system. The experimental procedures used to calibrate the detector and statistically evaluate its performance are given, and the sources of analytical error are cited. The limitations of the present system are also discussed

  9. Hydrogen gas sensing feature of polyaniline/titania (rutile) nanocomposite at environmental conditions

    Science.gov (United States)

    Milani Moghaddam, Hossain; Nasirian, Shahruz

    2014-10-01

    The resistance-based sensors of polyaniline/titania (rutile) nanocomposite (TPNC) were prepared by spin coating technique onto an epoxy glass substrate with Cu-interdigited electrodes to study their hydrogen (H2) gas sensing features. Our findings are that the change of the surface morphology, porosity and wt% of titania in TPNCs have a significant effect on H2 gas sensing of sensors. All of the sensors had a reproducibility response toward 0.8 vol% H2 gas at room temperature, air pressure and 50% relative humidity. A sensor with 40 wt% of titania nanoparticles had better response/recovery time and the response than other sensors. Moreover, H2 gas sensing mechanism of TPNC sensors based contact areas and the correlation of energy levels between PANI chains and the titania grains were studied.

  10. [Feasibility investigation of hydrogen instead of helium as carrier gas in the determination of five organophosphorus pesticides by gas chromatography-mass spectrometry].

    Science.gov (United States)

    Liu, Zhenxue; Zhou, Shixue

    2015-01-01

    Helium is almost the only choosable carrier gas used in gas chromatography-mass spectrometry (GC-MS). A mixed standard solution of five organophosphorus pesticides was analyzed by using GC-MS, and hydrogen or helium as carrier gas, so as to study the feasibility of hydrogen instead of helium as carrier gas for the determination of organophosphorus pesticides. Combining a mass spectrum database built by ourselves, the results were deconvolved and identified by Automated Mass Spectral Deconvolution & Identification System (AMDIS32), a software belonging to the workstation of the instrument. Then, the statistical software, IBM SPSS Statistics 19.0 was used for the clustering analysis of the data. The results indicated that when hydrogen was used as carrier gas, the peaks of the pesticides detected were slightly earlier than those when helium used as carrier gas, but the resolutions of the chromatographic peaks were lower, and the fraction good indices (Frac. Good) were lower, too. When hydrogen was used as carrier gas, the signals of the pesticides were unstable, the measuring accuracies of the pesticides were reduced too, and even more, some compounds were undetectable. Therefore, considering the measuring accuracy, the signal stability, and the safety, etc., hydrogen should be cautiously used as carrier gas in the determination of organophosphorus pesticides by GC-MS.

  11. Aqueous process for recovering sulfur from hydrogen sulfide-bearing gas

    Science.gov (United States)

    Basu, Arunabha

    2015-05-05

    A process for recovering sulfur from a hydrogen sulfide-bearing gas utilizes an aqueous reaction medium, a temperature of about 110-150.degree. C., and a high enough pressure to maintain the aqueous reaction medium in a liquid state. The process reduces material and equipment costs and addresses the environmental disadvantages associated with known processes that rely on high boiling point organic solvents.

  12. Process for Generation of Hydrogen Gas from Various Feedstocks Using Thermophilic Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Ooteghem Van, Suellen

    2005-09-13

    A method for producing hydrogen gas is provided comprising selecting a bacteria from the Order Thermotogales, subjecting the bacteria to a feedstock and to a suitable growth environment having an oxygen concentration below the oxygen concentration of water in equilibrium with air; and maintaining the environment at a predetermined pH and at a temperature of at least approximately 45 degrees C. for a time sufficient to allow the bacteria to metabolize the feedstock.

  13. A Robust Fiber Bragg Grating Hydrogen Gas Sensor Using Platinum-Supported Silica Catalyst Film

    OpenAIRE

    Marina Kurohiji; Seiji Ichiriyama; Naoki Yamasaku; Shinji Okazaki; Naoya Kasai; Yusuke Maru; Tadahito Mizutani

    2018-01-01

    A robust fiber Bragg grating (FBG) hydrogen gas sensor for reliable multipoint-leakage monitoring has been developed. The sensing mechanism is based on shifts of center wavelength of the reflection spectra due to temperature change caused by catalytic combustion heat. The sensitive film which consists of platinum-supported silica (Pt/SiO2) catalyst film was obtained using sol-gel method. The precursor solution was composed of hexachloroplatinic acid and commercially available silica precursor...

  14. Effects of Post-Treatment Hydrogen Gas Inhalation on Uveitis Induced by Endotoxin in Rats.

    Science.gov (United States)

    Yan, Weiming; Chen, Tao; Long, Pan; Zhang, Zhe; Liu, Qian; Wang, Xiaocheng; An, Jing; Zhang, Zuoming

    2018-06-07

    BACKGROUND Molecular hydrogen (H2) has been widely reported to have benefiicial effects in diverse animal models and human disease through reduction of oxidative stress and inflammation. The aim of this study was to investigate whether hydrogen gas could ameliorate endotoxin-induced uveitis (EIU) in rats. MATERIAL AND METHODS Male Sprague-Dawley rats were divided into a normal group, a model group, a nitrogen-oxygen (N-O) group, and a hydrogen-oxygen (H-O) group. EIU was induced in rats of the latter 3 groups by injection of lipopolysaccharide (LPS). After that, rats in the N-O group inhaled a gas mixture of 67% N2 and 33% O2, while those in the H-O group inhaled a gas mixture of 67% H2 and 33% O2. All rats were graded according to the signs of uveitis after electroretinography (ERG) examination. Protein concentration in the aqueous humor (AqH) was measured. Furthermore, hematoxylin-eosin staining and immunostaining of anti-ionized calcium-binding adapter molecule 1 (Iba1) in the iris and ciliary body (ICB) were carried out. RESULTS No statistically significant differences existed in the graded score of uveitis and the b-wave peak time in the Dark-adapted 3.0 ERG among the model, N-O, and H-O groups (P>0.05), while rats of the H-O group showed a lower concentration of AqH protein than that of the model or N-O group (P0.05), while the activation of microglia cells in the H-O group was somewhat reduced (Ptreatment hydrogen gas inhalation did not ameliorate the clinical signs, or reduce the infiltrating cells of EIU. However, it inhibited the elevation of protein in the AqH and reduced the microglia activation.

  15. Purification of inert gas circuits of nuclear power facilities from tritium and hydrogen

    International Nuclear Information System (INIS)

    Eichler, R.

    1985-08-01

    Removing hydrogen and tritium from the inert primary coolant of a high temperature reactor is very important in regard to the process heat disposition. In this work a gas purification for a high temperature module reactor was laid out constructionally and researched technically. This system removes the contamination of the primary circuit with the aid of chemical getter beds of Cer alloy particles. (orig./PW) [de

  16. The life cycle greenhouse gas emissions implications of power and hydrogen production for oil sands operations

    International Nuclear Information System (INIS)

    McKellar, J.M.; Bergerson, J.A.; MacLean, H.L.

    2009-01-01

    'Full text:' The Alberta Oil Sands represent a major economic opportunity for Canada, but the industry is also a significant source of greenhouse gas (GHG) emissions. One of the sources of these emissions is the use of natural gas for the production of electricity, steam and hydrogen. Due to concerns around resource availability and price volatility, there has been considerable discussion regarding the potential replacement of natural gas with an alternative fuel. While some of the options are non-fossil and could potentially reduce GHG emissions (e.g., nuclear, geothermal, biomass), others have the potential to increase emissions. A comparative life cycle assessment was completed to investigate the relative GHG emissions, energy consumption and financial implications of replacing natural gas with coal, coke, asphaltenes or bitumen for the supply of electricity, steam and hydrogen to oil sands operations. The potential use of carbon capture and storage (CCS) was also investigated as a means of reducing GHG emissions. Preliminary results indicate that, without CCS, the natural gas systems currently in use have lower life cycle GHG emissions than gasification systems using any of the alternative fuels analysed. However, when CCS is implemented in both the coke gasification and natural gas systems, the coke systems have lower GHG emissions and financial costs than the natural gas systems (assuming a 30-year project life and a natural gas price of 6.5 USD/gigajoule). The use of CCS does impose a financial penalty though, indicating that it is unlikely to be implemented without some financial incentive. While this study has limitations and uncertainties, the preliminary results indicate that although the GHG emissions of oil sands development pose a challenge to Canada, there are opportunities available for their abatement. (author)

  17. Gas-Phase Reaction Pathways and Rate Coefficients for the Dichlorosilane-Hydrogen and Trichlorosilane-Hydrogen Systems

    Science.gov (United States)

    Dateo, Christopher E.; Walch, Stephen P.

    2002-01-01

    As part of NASA Ames Research Center's Integrated Process Team on Device/Process Modeling and Nanotechnology our goal is to create/contribute to a gas-phase chemical database for use in modeling microelectronics devices. In particular, we use ab initio methods to determine chemical reaction pathways and to evaluate reaction rate coefficients. Our initial studies concern reactions involved in the dichlorosilane-hydrogen (SiCl2H2--H2) and trichlorosilane-hydrogen (SiCl2H-H2) systems. Reactant, saddle point (transition state), and product geometries and their vibrational harmonic frequencies are determined using the complete-active-space self-consistent-field (CASSCF) electronic structure method with the correlation consistent polarized valence double-zeta basis set (cc-pVDZ). Reaction pathways are constructed by following the imaginary frequency mode of the saddle point to both the reactant and product. Accurate energetics are determined using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations (CCSD(T)) extrapolated to the complete basis set limit. Using the data from the electronic structure calculations, reaction rate coefficients are obtained using conventional and variational transition state and RRKM theories.

  18. Hydrogen enrichment and separation from synthesis gas by the use of a membrane reactor

    International Nuclear Information System (INIS)

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

    2011-01-01

    One of the objectives of the CHRISGAS project was to study innovative gas separation and gas upgrading systems that have not been developed sufficiently yet to be tested at a demonstration scale within the time frame of the project, but which show some attractive merits and features for further development. In this framework CIEMAT studied, at bench scale, hydrogen enrichment and separation from syngas by the use of membranes and membrane catalytic reactors. In this paper results about hydrogen separation from synthesis gas by means of selective membranes are presented. Studies dealt with the evaluation of permeation and selectivity to hydrogen of prepared and pre-commercial Pd-based membranes. Whereas prepared membranes turned out to be non-selective, due to discontinuities of the palladium layer, studies conducted with the pre-commercial membrane showed that by means of a membrane reactor it is possible to completely separate hydrogen from the other gas components and produce pure hydrogen as a permeate stream, even in the case of complex reaction system (H 2 /CO/CO 2 /H 2 O) under WGS conditions gas mixtures. The advantages of using a water-gas shift membrane reactor (MR) over a traditional fixed bed reactor (TR) have also been studied. The experimental device included the pre-commercial Pd-based membrane and a commercial high temperature Fe-Cr-based, WGS catalyst, which was packed in the annulus between the membrane and the reactor outer shell. Results show that in the MR concept, removal of H 2 from the reaction side has a positive effect on WGS reaction, reaching higher CO conversion than in a traditional packed bed reactor at a given temperature. On increasing pressure on the reaction side permeation is enhanced and hence carbon monoxide conversion increases. -- Highlights: → H 2 enrichment and separation using a bench-scale membrane reactor MR is studied. → Permeation and selectivity to H 2 of Pd-based membranes was determined. → Complete separation

  19. Hydrogen from biomass gas steam reforming for low temperature fuel cell: energy and exergy analysis

    Directory of Open Access Journals (Sweden)

    A. Sordi

    2009-03-01

    Full Text Available This work presents a method to analyze hydrogen production by biomass gasification, as well as electric power generation in small scale fuel cells. The proposed methodology is the thermodynamic modeling of a reaction system for the conversion of methane and carbon monoxide (steam reforming, as well as the energy balance of gaseous flow purification in PSA (Pressure Swing Adsorption is used with eight types of gasification gases in this study. The electric power is generated by electrochemical hydrogen conversion in fuel cell type PEMFC (Proton Exchange Membrane Fuel Cell. Energy and exergy analyses are applied to evaluate the performance of the system model. The simulation demonstrates that hydrogen production varies with the operation temperature of the reforming reactor and with the composition of the gas mixture. The maximum H2 mole fraction (0.6-0.64 mol.mol-1 and exergetic efficiency of 91- 92.5% for the reforming reactor are achieved when gas mixtures of higher quality such as: GGAS2, GGAS4 and GGAS5 are used. The use of those gas mixtures for electric power generation results in lower irreversibility and higher exergetic efficiency of 30-30.5%.

  20. Integration of Wind Energy, Hydrogen and Natural Gas Pipeline Systems to Meet Community and Transportation Energy Needs: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Shahryar Garmsiri

    2014-04-01

    Full Text Available The potential benefits are examined of the “Power-to-Gas” (P2G scheme to utilize excess wind power capacity by generating hydrogen (or potentially methane for use in the natural gas distribution grid. A parametric analysis is used to determine the feasibility and size of systems producing hydrogen that would be injected into the natural gas grid. Specifically, wind farms located in southwestern Ontario, Canada are considered. Infrastructure requirements, wind farm size, pipeline capacity, geographical dispersion, hydrogen production rate, capital and operating costs are used as performance measures. The model takes into account the potential production rate of hydrogen and the rate that it can be injected into the local gas grid. “Straw man” systems are examined, centered on a wind farm size of 100 MW integrating a 16-MW capacity electrolysis system typically producing 4700 kg of hydrogen per day.

  1. Trace Analysis of Boron in Nuclear Graphite by Means of Gas Chromatography; Analyse de traces de bore dans le graphite nucleaire au moyen de la chromatographie gazeuse; Analiz metodom gazovoj khromatografii sledov bora v yadernom grafite; Analisis de vestigios de boro en el grafito nuclear por cromatografia de gases

    Energy Technology Data Exchange (ETDEWEB)

    Zado, F. [Rudjer Boskovlc Institute, Zagreb, Yugoslavia (Croatia)

    1963-11-15

    No literature is available about the application of gas chromatography in trace analysis of boron in graphite. The following methods of transformation of boron into its volatile compounds are discussed: (a) Ignition of graphite in a stream of oxygen and subsequent transformation of boron oxide into volatile methyl borate which is then analysed on a Dilkens Aerograph H Model 96 gas chromatograph with silicone column and hydrogen as carrier (concentration method). (b) Extraction of boron from the graphite by means of sodium fluoride at 2800{sup o}C with simultaneous chlorination and trapping of boron trichloride, which is then analysed (direct method). A home-made gas chromatograph with a thermal conductivity detector and nitrogen as a carrier was used. The column was made of glass with a 20% (wt./wt.) fluorocarbon oil on kieselguhr. Special precautions were taken on account of the sensitivity of boron trichloride to moisture. (author) [French] Rien n'a ete publie sur l'application de la chromatographie gazeuse a l'analyse de traces de bore dans le graphite. L'auteur examine les methodes suivantes de transformation du bore en composes volatils: a) Brulage du graphite dans un courant d'oxygene, puis transformation de l'oxyde de bore en borate de methyle volatil, que l'on analyse ensuite a l'aide d'un appareil a chromatographie gazeuse Dilkens Aerograph H, Modele 96, utilisant une colonne de silicium et de rhydrogene comme entrafheur (methode de concentration). b) Extraction du bore contenu dans le graphite par chauffage avec du fluorure de sodium a 2800{sup o}C, avec chloruration simultanee et captage du trichlorure de bore qui est ensuite analyse (methode directe). On s' est servi d'un appareil a chromatographie gazeuse construit sur place, dote d'un detecteur a conductibilite thermique et utilisant l'azote comme entrafheur. La colonne etait faite de verre contenant 20% en poids de fluorocarbure huileux sur du kieselguhr. Des precautions particulieres ont ete prises

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

    NARCIS (Netherlands)

    Al Tarazi, M.Y.M.

    2004-01-01

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

  3. DECONTAMINATION ASSESSMENT OF BACILLUS ANTHRACIS, BACILLUS SUBTILIS, AND GEOBACILLUS STEAROTHERMOPHILUS SPORES ON INDOOR SURFACTS USING A HYDROGEN PERIOXIDE GAS GENERATOR

    Science.gov (United States)

    Aims: To evaluate the decontamination of Bacillus anthracis, Bacillus subtilis, and Geobacillus stearothermophilus spores on indoor surface materials using hydrogen peroxide gas. Methods and Results: B. anthracis, B. subtilis, and G. Stearothermophilus spores were dried on seven...

  4. Engineering Development of Ceramic Membrane Reactor System for Converting Natural Gas to Hydrogen and Synthesis Gas for Liquid Transportation Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Air Products and Chemicals

    2008-09-30

    An Air Products-led team successfully developed ITM Syngas technology from the concept stage to a stage where a small-scale engineering prototype was about to be built. This technology produces syngas, a gas containing carbon monoxide and hydrogen, by reacting feed gas, primarily methane and steam, with oxygen that is supplied through an ion transport membrane. An ion transport membrane operates at high temperature and oxygen ions are transported through the dense membrane's crystal lattice when an oxygen partial pressure driving force is applied. This development effort solved many significant technical challenges and successfully scaled-up key aspects of the technology to prototype scale. Throughout the project life, the technology showed significant economic benefits over conventional technologies. While there are still on-going technical challenges to overcome, the progress made under the DOE-funded development project proved that the technology was viable and continued development post the DOE agreement would be warranted.

  5. Consideration on developing of leaked inflammable gas detection system for HTGR hydrogen production system

    International Nuclear Information System (INIS)

    Nishihara, Tetsuo; Nakamura, Masashi

    1999-09-01

    One of most important safety design issues for High Temperature Gas-cooled Reactor (HTGR) - Hydrogen Production System (HTGR-HPS) is to ensure reactor safety against fire and explosion at the hydrogen production plant. The inflammable gas mixture in the HTGR-HPS does not use oxygen in any condition and are kept in high pressure in the normal operation. The piping system and/or heat transfer tubes which have the potential possibility of combustible materials ingress into the Reactor Building (R/B) due to the failure are designed to prevent the failure against any events. Then, it is not necessary to consider their self-combustion in vessels nor leakage in the R/B. The only one case which we must consider is the ex-building fire or explosion caused by their leakage from piping or vessel. And it is important to mitigate their effects by means of early detection of gas leakage. We investigated our domestic standards on gas detection, applications of gas detectors, their detection principles, performance, sensitivity, reliability, their technical trends, and so on. We proposed three gas detection systems which may be applied in HTGR-HPS. The first one is the universal solid sensor system; it may be applied when there is no necessity to request their safety credits. The second is the combination of the improved solid sensor system and enhanced beam detector system; it may be applied when it is necessary to request their safety credit. And the third is the combination of the universal solid sensor system and the existing beam detector system; it may be applied when the plant owner request higher detector sensitivity than usual, from the view point of public acceptance, though there is not necessity to request their safety credits. To reduce the plant cost by refusing of safety credits to the gas leakage detection system, we proposed that the equipment required to isolate from others should be installed in the inertrized compartments. (author)

  6. A three-dimensional methodology for the assessment of neutron damage and nuclear energy deposition in graphite components of advanced gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, D.O.; Robinson, A.T.; Allen, D.A.; Picton, D.J.; Thornton, D.A. [TCS, Serco, Rutherford House, Olympus Park, Quedgeley, Gloucester, Gloucestershire GL2 4NF (United Kingdom); Shaw, S.E. [EDF Energy, Barnet Way, Barnwood, Gloucester GL4 3RS (United Kingdom)

    2011-07-01

    This paper describes the development of a three-dimensional methodology for the assessment of neutron damage and nuclear energy deposition (or nuclear heating) throughout the graphite cores of the UK's Advanced Gas-cooled Reactors. Advances in the development of the Monte Carlo radiation transport code MCBEND have enabled the efficient production of detailed fully three-dimensional models that utilise three-dimensional source distributions obtained from Core Follow data supplied by the reactor physics code PANTHER. The calculational approach can be simplified to reduce both the requisite number of intensive radiation transport calculations, as well as the quantity of data output. These simplifications have been qualified by comparison with explicit calculations and they have been shown not to introduce significant systematic uncertainties. Simple calculational approaches are described that allow users of the data to address the effects on neutron damage and nuclear energy deposition predictions of the feedback resulting from the mutual dependencies of graphite weight loss and nuclear energy deposition. (authors)

  7. Experiments on graphite block gaps connected with leak flow in bottom-core structure of experimental very high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Kikuchi, Kenji; Futakawa, Masatoshi; Takizuka, Takakazu; Kaburaki, Hideo; Sanokawa, Konomo

    1984-01-01

    In order to minimize the leak flow rate of an experimental VHTR (a multi-purpose very high-temperature gas-cooled reactor), the graphite blocks are tightened to reduce the gap distance between blocks by core restrainers surrounded outside of the fixed reflectors of the bottom-core structure and seal elements are placed in the gaps. By using a 1/2.75-scale model of the bottom-core structure, the experiments on the following items have been carried out: a relationship between core restraint force and block gap, a relationship between core restraint force and inclined angle of the model, leak flow characteristics of seal elements etc. The conclusions derived from the experiments are as follows: (1) Core restraint force is significantly effective for decreasing the gap distance between hot plenum blocks, but ineffective for the gap between hot plenum block and fixed reflector. (2) Graphite seal element reduces the leak flow rate from the top surface of hot plenum block into plenum region to one-third. (author)

  8. Hydrogen safety risk assessment methodology applied to a fluidized bed membrane reactor for autothermal reforming of natural gas

    NARCIS (Netherlands)

    Psara, N.; Van Sint Annaland, M.; Gallucci, F.

    2015-01-01

    The scope of this paper is the development and implementation of a safety risk assessment methodology to highlight hazards potentially prevailing during autothermal reforming of natural gas for hydrogen production in a membrane reactor, as well as to reveal potential accidents related to hydrogen

  9. 40 CFR 266.107 - Standards to control hydrogen chloride (HCl) and chlorine gas (Cl2) emissions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Standards to control hydrogen chloride... WASTES AND SPECIFIC TYPES OF HAZARDOUS WASTE MANAGEMENT FACILITIES Hazardous Waste Burned in Boilers and Industrial Furnaces § 266.107 Standards to control hydrogen chloride (HCl) and chlorine gas (Cl2) emissions...

  10. Hydrogen gas sensing feature of polyaniline/titania (rutile) nanocomposite at environmental conditions

    Energy Technology Data Exchange (ETDEWEB)

    Milani Moghaddam, Hossain, E-mail: hossainmilani@yahoo.com [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Nasirian, Shahruz [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Basic Sciences Department, Mazandaran University of Science and Technology, Babol (Iran, Islamic Republic of)

    2014-10-30

    Graphical abstract: - Highlights: • Polyaniline/titania (rutile) nanocomposite (TPNC) was synthesized by a chemical oxidative polymerization method. • Surface morphology and titania (rutile) wt% in TPNC sensors were significant factors for H{sub 2} gas sensing. • TPNC sensors could be used for H{sub 2} gas sensing at different R.H. humidity. • TPNC Sensors exhibited considerable sensitive, reversible and repeatable response to H{sub 2} gas at environmental conditions. - Abstract: The resistance-based sensors of polyaniline/titania (rutile) nanocomposite (TPNC) were prepared by spin coating technique onto an epoxy glass substrate with Cu-interdigited electrodes to study their hydrogen (H{sub 2}) gas sensing features. Our findings are that the change of the surface morphology, porosity and wt% of titania in TPNCs have a significant effect on H{sub 2} gas sensing of sensors. All of the sensors had a reproducibility response toward 0.8 vol% H{sub 2} gas at room temperature, air pressure and 50% relative humidity. A sensor with 40 wt% of titania nanoparticles had better response/recovery time and the response than other sensors. Moreover, H{sub 2} gas sensing mechanism of TPNC sensors based contact areas and the correlation of energy levels between PANI chains and the titania grains were studied.

  11. Hydrogen Oxidation on Gas Diffusion Electrodes for Phosphoric Acid Fuel Cells in the Presence of Carbon Monoxide and Oxygen

    DEFF Research Database (Denmark)

    Gang, Xiao; Li, Qingfeng; Hjuler, Hans Aage

    1995-01-01

    Hydrogen oxidation has been studied on a carbon-supported platinum gas diffusion electrode in a phosphoric acidelectrolyte in the presence of carbon monoxide and oxygen in the feed gas. The poisoning effect of carbon monoxide presentin the feed gas was measured in the temperature range from 80...... to 150°C. It was found that throughout the temperaturerange, the potential loss due to the CO poisoning can be reduced to a great extent by the injection of small amounts ofgaseous oxygen into the hydrogen gas containing carbon monoxide. By adding 5 volume percent (v/o) oxygen, an almost...

  12. Fiscal 1975 Sunshine Project research report. General research on hydrogen energy subsystems and their peripheral technologies (Research on hydrogen gas turbine); 1975 nendo suiso riyo subsystem no sogoteki kento to shuhen gijutsu ni kansuru kenkyu seika hokokusho. Suiso gas turbine ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1976-03-31

    This research aims at establishment of the meaning of using hydrogen as gas turbine fuel in the hydrogen energy system and various conditions for hydrogen gas turbines, and approaches to the feasibility study and R and D of hydrogen gas turbines in the future. In fiscal 1975, researches were made on (1) feasibility study on hydrogen-oxygen gas turbine, (2) establishment of various conditions for technical, social and economic realization of hydrogen gas turbines in the total energy system, and (3) study on technical troubles to be solved for realization of hydrogen gas turbines. For the above researches, study was made on hydrogen combustion based on the hydrogen combustion test result of gas mixture including hydrogen, and on the feasibility of aphodid cycle. In addition, study on the applicability of hydrogen-oxygen gas turbines, comparative study on hydrogen-oxygen gas turbine, MHD power generation and fuel cell, and the future prospect of hydrogen gas turbines for ships were made to place this hydrogen gas turbine. (NEDO)

  13. Reduced-order modellin for high-pressure transient flow of hydrogen-natural gas mixture

    Science.gov (United States)

    Agaie, Baba G.; Khan, Ilyas; Alshomrani, Ali Saleh; Alqahtani, Aisha M.

    2017-05-01

    In this paper the transient flow of hydrogen compressed-natural gas (HCNG) mixture which is also referred to as hydrogen-natural gas mixture in a pipeline is numerically computed using the reduced-order modelling technique. The study on transient conditions is important because the pipeline flows are normally in the unsteady state due to the sudden opening and closure of control valves, but most of the existing studies only analyse the flow in the steady-state conditions. The mathematical model consists in a set of non-linear conservation forms of partial differential equations. The objective of this paper is to improve the accuracy in the prediction of the HCNG transient flow parameters using the Reduced-Order Modelling (ROM). The ROM technique has been successfully used in single-gas and aerodynamic flow problems, the gas mixture has not been done using the ROM. The study is based on the velocity change created by the operation of the valves upstream and downstream the pipeline. Results on the flow characteristics, namely the pressure, density, celerity and mass flux are based on variations of the mixing ratio and valve reaction and actuation time; the ROM computational time cost advantage are also presented.

  14. Hydrogen Gas Retention and Release from WTP Vessels: Summary of Preliminary Studies

    Energy Technology Data Exchange (ETDEWEB)

    Gauglitz, Phillip A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bontha, Jagannadha R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Daniel, Richard C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mahoney, Lenna A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rassat, Scot D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wells, Beric E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bao, Jie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Boeringa, Gregory K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Buchmiller, William C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Burns, Carolyn A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chun, Jaehun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Karri, Naveen K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Huidong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tran, Diana N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-01

    The Hanford Waste Treatment and Immobilization Plant (WTP) is currently being designed and constructed to pretreat and vitrify a large portion of the waste in the 177 underground waste storage tanks at the Hanford Site. A number of technical issues related to the design of the pretreatment facility (PTF) of the WTP have been identified. These issues must be resolved prior to the U.S. Department of Energy (DOE) Office of River Protection (ORP) reaching a decision to proceed with engineering, procurement, and construction activities for the PTF. One of the issues is Technical Issue T1 - Hydrogen Gas Release from Vessels (hereafter referred to as T1). The focus of T1 is identifying controls for hydrogen release and completing any testing required to close the technical issue. In advance of selecting specific controls for hydrogen gas safety, a number of preliminary technical studies were initiated to support anticipated future testing and to improve the understanding of hydrogen gas generation, retention, and release within PTF vessels. These activities supported the development of a plan defining an overall strategy and approach for addressing T1 and achieving technical endpoints identified for T1. Preliminary studies also supported the development of a test plan for conducting testing and analysis to support closing T1. Both of these plans were developed in advance of selecting specific controls, and in the course of working on T1 it was decided that the testing and analysis identified in the test plan were not immediately needed. However, planning activities and preliminary studies led to significant technical progress in a number of areas. This report summarizes the progress to date from the preliminary technical studies. The technical results in this report should not be used for WTP design or safety and hazards analyses and technical results are marked with the following statement: “Preliminary Technical Results for Planning – Not to be used for WTP Design

  15. Study on introduction scenario of the high temperature gas-cooled reactor hydrogen cogeneration system (GTHTR300C). Part 1

    International Nuclear Information System (INIS)

    Nishihara, Tetsuo; Takeda, Tetsuaki

    2005-09-01

    Japan Atomic Energy Research Institute is carrying out the research and development of the high temperature gas-cooled reactor hydrogen cogeneration system (GTHTR300C) aiming at the practical use around 2030. Preconditions of GTHTR300C introduction are the increase of hydrogen demand and the needs of new nuclear power plants. In order to establish the introduction scenario, it should be clarified that the operational status of existing nuclear power plants, the introduction number of fuel cell vehicles as a main user of hydrogen and the capability of hydrogen supply by existing plants. In this report, estimation of the nuclear power plants that will be decommissioned with a high possibility by 2030 and selection of the model district where the GTHTR300C can be introduced as an alternative system are conducted. Then the hydrogen demand and the capability of hydrogen supply in this district are investigated and the hydrogen supply scenario in 2030 is considered. (author)

  16. Experimental Evaluation of SI Engine Operation Supplemented by Hydrogen Rich Gas from a Compact Plasma Boosted Reformer

    International Nuclear Information System (INIS)

    J. B. Green, Jr.; N. Domingo; J. M. E. Storey; R.M. Wagner; J.S. Armfield; L. Bromberg; D. R. Cohn; A. Rabinovich; N. Alexeev

    2000-01-01

    It is well known that hydrogen addition to spark-ignited (SI) engines can reduce exhaust emissions and increase efficiency. Micro plasmatron fuel converters can be used for onboard generation of hydrogen-rich gas by partial oxidation of a wide range of fuels. These plasma-boosted microreformers are compact, rugged, and provide rapid response. With hydrogen supplement to the main fuel, SI engines can run very lean resulting in a large reduction in nitrogen oxides (NO x ) emissions relative to stoichiometric combustion without a catalytic converter. This paper presents experimental results from a microplasmatron fuel converter operating under variable oxygen to carbon ratios. Tests have also been carried out to evaluate the effect of the addition of a microplasmatron fuel converter generated gas in a 1995 2.3-L four-cylinder SI production engine. The tests were performed with and without hydrogen-rich gas produced by the plasma boosted fuel converter with gasoline. A one hundred fold reduction in NO x due to very lean operation was obtained under certain conditions. An advantage of onboard plasma-boosted generation of hydrogen-rich gas is that it is used only when required and can be readily turned on and off. Substantial NO x reduction should also be obtainable by heavy exhaust gas recirculation (EGR) facilitated by use of hydrogen-rich gas with stoichiometric operation

  17. Hydrogen production with fully integrated fuel cycle gas and vapour core reactors

    International Nuclear Information System (INIS)

    Anghaie, S.; Smith, B.

    2004-01-01

    This paper presents results of a conceptual design study involving gas and vapour core reactors (G/VCR) with a combined scheme to generate hydrogen and power. The hydrogen production schemes include high temperature electrolysis as well as two dominant thermochemical hydrogen production processes. Thermochemical hydrogen production processes considered in this study included the calcium-bromine process and the sulphur-iodine processes. G/VCR systems are externally reflected and moderated nuclear energy systems fuelled by stable uranium compounds in gaseous or vapour phase that are usually operated at temperatures above 1500 K. A gas core reactor with a condensable fuel such as uranium tetrafluoride (UF 4 ) or a mixture of UF 4 and other metallic fluorides (BeF 2 , LiF, KF, etc.) is commonly known as a vapour core reactor (VCR). The single most relevant and unique feature of gas/vapour core reactors is that the functions of fuel and coolant are combined into one. The reactor outlet temperature is not constrained by solid fuel-cladding temperature limits. The maximum fuel/working fluid temperature in G/VCR is only constrained by the reactor vessel material limits, which is far less restrictive than the fuel clad. Therefore, G/VCRs can potentially provide the highest reactor and cycle temperature among all existing or proposed fission reactor designs. Gas and vapour fuel reactors feature very low fuel inventory and fully integrated fuel cycle that provide for exceptional sustainability and safety characteristics. With respect to fuel utilisation, there is no fuel burn-up limit for gas core reactors due to continuous recycling of the fuel. Owing to the flexibility in nuclear design characteristics of cavity reactors, a wide range of conversion ratio from completely burner to breeder is achievable. The continuous recycling of fuel in G/VCR systems allow for complete burning of actinides without removing and reprocessing of the fuel. The only waste products at the back

  18. Fractionation of oxygen and hydrogen isotopes at the hydrate gas forming in the sea sediments

    International Nuclear Information System (INIS)

    Pashkina, V.I.; Esikov, A.D.

    1990-01-01

    The paper gives data on isotope composition of interstitial and near-bottom waters sampled in a region of gas-hydrate formation in the Sea of Okhotsk. The studies show that heavy isotopes of oxygen and hydrogen is used in gas-hydrate formation, with the result that isotope composition of its constitution water constitutes δ 18 O=+1.99per mille, δD=+23per mille relatively to SMOW. Formation of autogenic carbonates leads to isotope exchange with interstitial water wich, in turn, changes its primary isotope composition in the direction of increasing of O-18 content. The near-bottom waters are isotope-light relatively to the SMOW standard and to the mean isotope composition of interstitial water in the studied region of gas-hydrate spreading. (orig.) [de

  19. Experimental studies on hydrogen isotopic deuterium from gas to liquid phase by catalytic exchange

    International Nuclear Information System (INIS)

    Luo Yangming; Wang Heyi; Liu Jun; Fu Zhonghua; Wang Changbin; Han Jun; Xia Xiulong; Tang Lei

    2005-01-01

    The experimental studies on hydrogen isotopic deuterium from gas to liquid phase were completed by mixed ratio 1:4 of Pt-SDB hydrophobic catalyst and hydrophilic packing. The influencing factors on number of transfer units (NTU) and transformation efficiencies of deuterium were researched. The results show that preferable NTU can be obtained by choosing suitable operational temperature and flux of exchange gas. The transformation rate increases with increasing liquid flux, but it cannot obviously be improved when liquid flux attains some level. The length of catalytic column has an obvious influence on transformation rate and 90% of transformation rate is obtained by 4 m column length at gas flux with 2 m 3 /h, liquid flux with 1-2 kg/h and 45 degree C. (author)

  20. Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    Science.gov (United States)

    Zhamu, Aruna; Jang, Bor Z.

    2014-06-17

    A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

  1. Status and integration of the gas generation studies performed for the Hydrogen Safety Program

    International Nuclear Information System (INIS)

    Pederson, L.R.; Strachan, D.M.

    1993-02-01

    Waste in Tank 241-SY-101 on the Hanford Site generates and periodically releases hydrogen, nitrous oxide, and nitrogen gases. Studies have been conducted at several laboratories to determine the chemical mechanisms for the gas generation and release. Results from these studies are presented and integrated in an attempt to describe current understanding of the physical properties of the waste and the mechanisms of gas generation and retention. Existing tank data are consistent with the interpretation that gases are uniformly generated in the tank, released continuously from the convecting layer, and stored in the nonconvecting layer. Tank temperature measurements suggest that the waste consists of ''gobs'' of material that reach neutral buoyancy at different times. The activation energy of the rate limiting step of the gas generating process was calculated to be about 7 kJ/mol but measured in the laboratory at 80 to 100 kJ/mol. Based on observed temperature changes in the tank the activation energy is probably not higher than about 20 kJ/mol. Several simulated waste compositions have been devised for use in laboratory studies in the place of actual waste from Tank 241-SY-101. Data from these studies can be used to predict how the actual waste might behave when heated or diluted. Density evaluations do not confirm that heating waste at the bottom of the tank would induce circulation within the waste; however, heating may release gas bubbles by dissolving the solids to which the bubbles adhere. Gas generation studies on simulated wastes indicated that nitrous oxide and hydrogen yields are not particularly coupled. Solubility studies of nitrous oxide, the most soluble of the principal gaseous products, indicate it is unlikely that dissolved gases contribute substantially to the quantity of gas released during periodic events

  2. Hydrogen sensor

    Science.gov (United States)

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing

    2010-11-23

    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  3. Hydrogen production from biomass pyrolysis gas via high temperature steam reforming process

    International Nuclear Information System (INIS)

    Wongchang, Thawatchai; Patumsawad, Suthum

    2010-01-01

    Full text: The aim of this work has been undertaken as part of the design of continuous hydrogen production using the high temperature steam reforming process. The steady-state test condition was carried out using syngas from biomass pyrolysis, whilst operating at high temperatures between 600 and 1200 degree Celsius. The main reformer operating parameters (e.g. temperature, resident time and steam to biomass ratio (S/B)) have been examined in order to optimize the performance of the reformer. The operating temperature is a key factor in determining the extent to which hydrogen production is increased at higher temperatures (900 -1200 degree Celsius) whilst maintaining the same as resident time and S/B ratio. The effects of exhaust gas composition on heating value were also investigated. The steam reforming process produced methane (CH 4 ) and ethylene (C 2 H 4 ) between 600 to 800 degree Celsius and enhanced production ethane (C 2 H 6 ) at 700 degree Celsius. However carbon monoxide (CO) emission was slightly increased for higher temperatures all conditions. The results show that the use of biomass pyrolysis gas can produce higher hydrogen production from high temperature steam reforming. In addition the increasing reformer efficiency needs to be optimized for different operating conditions. (author)

  4. Microbial Electrodialysis Cell for Simultaneous Water Desalination and Hydrogen Gas Production

    KAUST Repository

    Mehanna, Maha; Kiely, Patrick D.; Call, Douglas F.; Logan, Bruce. E.

    2010-01-01

    A new approach to water desalination is to use exoelectrogenic bacteria to generate electrical power from the biodegradation of organic matter, moving charged ions from a middle chamber between two membranes in a type of microbial fuel cell called a microbial desalination cell. Desalination efficiency using this approach is limited by the voltage produced by the bacteria. Here we examine an alternative strategy based on boosting the voltage produced by the bacteria to achieve hydrogen gas evolution from the cathode using a three-chambered system we refer to as a microbial electrodialysis cell (MEDC). We examined the use of the MEDC process using two different initial NaCl concentrations of 5 g/L and 20 g/L. Conductivity in the desalination chamber was reduced by up to 68 ± 3% in a single fed-batch cycle, with electrical energy efficiencies reaching 231 ± 59%, and maximum hydrogen production rates of 0.16 ± 0.05 m3 H2/m3 d obtained at an applied voltage of 0.55 V. The advantage of this system compared to a microbial fuel cell approach is that the potentials between the electrodes can be better controlled, and the hydrogen gas that is produced can be used to recover energy to make the desalination process self-sustaining with respect to electrical power requirements. © 2010 American Chemical Society.

  5. A Robust Fiber Bragg Grating Hydrogen Gas Sensor Using Platinum-Supported Silica Catalyst Film

    Directory of Open Access Journals (Sweden)

    Marina Kurohiji

    2018-01-01

    Full Text Available A robust fiber Bragg grating (FBG hydrogen gas sensor for reliable multipoint-leakage monitoring has been developed. The sensing mechanism is based on shifts of center wavelength of the reflection spectra due to temperature change caused by catalytic combustion heat. The sensitive film which consists of platinum-supported silica (Pt/SiO2 catalyst film was obtained using sol-gel method. The precursor solution was composed of hexachloroplatinic acid and commercially available silica precursor solution. The atom ratio of Si : Pt was fixed at 13 : 1. A small amount of this solution was dropped on the substrate and dried at room temperature. After that, the film was calcined at 500°C in air. These procedures were repeated and therefore thick hydrogen-sensitive films were obtained. The catalytic film obtained by 20-time coating on quartz glass substrate showed a temperature change 75 K upon exposure to 3 vol.% H2. For realizing robust sensor device, this catalytic film was deposited and FBG portion was directly fixed on titanium substrate. The sensor device showed good performances enough to detect hydrogen gas in the concentration range below lower explosion limit at room temperature. The enhancement of the sensitivity was attributed to not only catalytic combustion heat but also related thermal strain.

  6. Plasma-neutral gas interaction in a tokamak divertor: effects of hydrogen molecules and plasma recombination

    International Nuclear Information System (INIS)

    Krasheninnikov, S.I.; Pigarov, A.Yu.; Soboleva, T.K.; Sigmar, D.J.

    1997-01-01

    We investigate the influence of hydrogen molecules on plasma recombination using a collisional-radiative model for multispecies hydrogen plasmas and tokamak detached divertor parameters. The rate constant found for molecular activated recombination of a plasma can be as high as 2 x 10 -10 cm 3 /s, confirming our pervious estimates. We investigate the effects of hydrogen molecules and plasma recombination on self-consistent plasma-neutral gas interactions in the recycling region of a tokamak divertor. We treat the plasma flow in a fluid approximation retaining the effects of plasma recombination and employing a Knudsen neutral transport model for a 'gas box' divertor geometry. For the model of plasma-neutral interactions we employ we find: (a) molecular activated recombination is a dominant channel of divertor plasma recombination; and (b) plasma recombination is a key element leading to a decrease in the plasma flux onto the target and substantial plasma pressure drop which are the main features of detached divertor regimes. (orig.)

  7. Microbial Electrodialysis Cell for Simultaneous Water Desalination and Hydrogen Gas Production

    KAUST Repository

    Mehanna, Maha

    2010-12-15

    A new approach to water desalination is to use exoelectrogenic bacteria to generate electrical power from the biodegradation of organic matter, moving charged ions from a middle chamber between two membranes in a type of microbial fuel cell called a microbial desalination cell. Desalination efficiency using this approach is limited by the voltage produced by the bacteria. Here we examine an alternative strategy based on boosting the voltage produced by the bacteria to achieve hydrogen gas evolution from the cathode using a three-chambered system we refer to as a microbial electrodialysis cell (MEDC). We examined the use of the MEDC process using two different initial NaCl concentrations of 5 g/L and 20 g/L. Conductivity in the desalination chamber was reduced by up to 68 ± 3% in a single fed-batch cycle, with electrical energy efficiencies reaching 231 ± 59%, and maximum hydrogen production rates of 0.16 ± 0.05 m3 H2/m3 d obtained at an applied voltage of 0.55 V. The advantage of this system compared to a microbial fuel cell approach is that the potentials between the electrodes can be better controlled, and the hydrogen gas that is produced can be used to recover energy to make the desalination process self-sustaining with respect to electrical power requirements. © 2010 American Chemical Society.

  8. Two-dimensional gas chromatography-online hydrogenation for improved characterization of petrochemical samples.

    Science.gov (United States)

    Potgieter, H; Bekker, R; Govender, A; Rohwer, E

    2016-05-06

    The Fischer-Tropsch (FT) process produces a variety of hydrocarbons over a wide carbon number range and during subsequent product workup a large variety of synthetic fuels and chemicals are produced. The complexity of the product slate obtained from this process is well documented and the high temperature FT (HT-FT) process products are spread over gas, oil and water phases. The characterization of these phases is very challenging even when using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS). Despite the increase in separation power, peak co-elution still occurs when samples containing isomeric compounds are analysed by comprehensive two dimensional GC. The separation of isomeric compounds with the same double bond equivalents is especially difficult since these compounds elute in a similar position on the GC×GC chromatogram and have identical molecular masses and similar fragmentation patterns in their electron ionization (EI) mass spectra. On-line hydrogenation after GC×GC separation is a possible way to distinguish between these isomeric compounds since the number of rings and alkene double bonds can be determined from the mass spectra of the compounds before and after hydrogenation. This paper describes development of a GC×GC method with post column hydrogenation for the determination of the backbone of cyclic/olefinic structures enabling us to differentiate between classes like dienes and cyclic olefins in complex petrochemical streams. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. The impact of hydrogen-bearing gas to change indexes of car engine in operating conditions

    Directory of Open Access Journals (Sweden)

    Korpach A.

    2016-08-01

    Full Text Available Due to lower oil and petroleum products there is a constant problem of the growing use of alternative fuels. One of the most promising is hydrogen, but its use as a self-fuel is rather difficult, but using as the form of supplements has prospects for widespread use in road transport. In order to establish the effectiveness of its use as a hydrogen-containing gas as a product of the electrolysis of the alkaline solution, a series of tests conducted. Tests were carried out on the car ZAZ–1102 "Tavria", which is equipped with an engine MeMZ–245 with carburetor feed system and electrolyser SuperKit 10, which is powered by the vehicle electrical system. At the same time also used electrolytic League–02. The effect on fuel economy additives hydrogen-containing gas to the air charge is determined when the engine is idling. When using additives 1,34 % interest, from the weight of the fuel, fuel efficiency has increased by 1,9 %.

  10. Numerical investigation on the effects of natural gas and hydrogen blends on engine combustion

    Energy Technology Data Exchange (ETDEWEB)

    Morrone, Biagio; Unich, Andrea [Dipartimento di Ingegneria Aerospaziale e Meccanica (DIAM), Seconda Universita degli Studi di Napoli via Roma 29, 81031 Aversa (CE) (Italy)

    2009-05-15

    The use of hydrogen blended with natural gas is a viable alternative to pure fossil fuels because of the expected reduction of the total pollutant emissions and increase of efficiency. These blends offer a valid opportunity for tackling sustainable transportation, in view of the future stringent emission limits for road vehicles. The aim of the present paper is the investigation of the performance of internal combustion engines fuelled by such blends. A numerical investigation on the characteristics of natural gas-hydrogen blends as well as their effect on engine performance is carried out. The activity is focused on the influence of such blends on flame propagation speed. Combustion pattern modelling allows the comparison of engine brake efficiency and power output using different fuels. Results showed that there is an increase in engine efficiency only if Maximum Brake Torque (MBT) spark advance is used for each fuel. Moreover, an economic analysis has been carried out to determine the over cost of hydrogen in such blends, showing percent increments by using these fuels about between 10 and 34%. (author)

  11. Analysis of Gas Separated for Silica Membrane in Hydrogen Gas Production by Using Nuclear Reactor Thermal

    International Nuclear Information System (INIS)

    Pandiangan, Tumpal

    2007-01-01

    One of the hydrogen production method that have been developed is a thermo-chemical method. This method is permissible to increase thermal efficiency up to 70 % and to decrease of operational temperature from 800℃ down to 450 ℃. One of several factor that can increase of the hydrogen production thermal efficiency at the above method is to apply a separated membrane that have a relative good for permeansce and selectivity performance. It had been carried out for analyzing of time and temperature CVD (Chemical Vapouration Deposition) that is affected to permeansce and power selecting performance of the membrane. The layering membrane silica process was carried out by means of the CVD method at atmosphere pressure. The membrane silica layering that was observed was developed by a CVD method in atmospheric pressure. The silica membrane was formed at the out side surface of the alumina gamma cylinder that had been coated by alumina gamma which it has average porosity about of 0.01 mic.meter. A permeansce and separation power performance of the membrane silica that was carried out by means of CVD method at 600 ℃ on H 2 , He and N 2 are : 2 x 10 -10 , 9 x 10 -9 and 4 x 10 -7 mol Pa/m 2 s and the selected power of H 2 /N 2 = 45. The permeansce of that membrane is relative good but the selected power is relative not so good. (author)

  12. Fiber optic hydrogen gas sensor utilizing surface plasmon resonance and native defects of zinc oxide by palladium

    International Nuclear Information System (INIS)

    Tabassum, Rana; Gupta, Banshi D

    2016-01-01

    We present an experimental study on a surface plasmon resonance (SPR) based fiber optic hydrogen gas sensor employing a palladium doped zinc oxide nanocomposite (ZnO (1−x) Pd x , 0 ≤ x ≤ 0.85) layer over the silver coated unclad core of the fiber. Palladium doped zinc oxide nanocomposites (ZnO (1−x) Pd x )  are prepared by a chemical route for different composition ratios and their structural, morphological and hydrogen sensing properties are investigated experimentally. The sensing principle involves the absorption of hydrogen gas by ZnO (1−x) Pd x , altering its dielectric function. The change in the dielectric constant is analyzed in terms of the red shift of the resonance wavelength in the visible region of the electromagnetic spectrum. To check the sensing capability of sensing probes fabricated with varying composition ratio (x) of nanocomposite, the SPR curves are recorded typically for 0% H 2 and 4% H 2 in N 2 atmosphere for each fabricated probe. On changing the concentration of hydrogen gas from 0% to 4%, the red shift in the SPR spectrum confirms the change in dielectric constant of ZnO (1−x) Pd x on exposure to hydrogen gas. It is noted that the shift in the SPR spectrum increases monotonically up to a certain fraction of Pd in zinc oxide, beyond which it starts decreasing. SEM images and the photoluminescence (PL) spectra reveal that Pd dopant atoms substitutionally incorporated into the ZnO lattice profoundly affect its defect levels; this is responsible for the optimal composition of ZnO (1−x) Pd x to sense the hydrogen gas. The sensor is highly selective to hydrogen gas and possesses high sensitivity. Since optical fiber sensing technology is employed along with the SPR technique, the present sensor is capable of remote sensing and online monitoring of hydrogen gas. (paper)

  13. Evaluation of Technical Feasibility of Homogeneous Charge Compression Ignition (HCCI) Engine Fueled with Hydrogen, Natural Gas, and DME

    Energy Technology Data Exchange (ETDEWEB)

    John Pratapas; Daniel Mather; Anton Kozlovsky

    2007-03-31

    The objective of the proposed project was to confirm the feasibility of using blends of hydrogen and natural gas to improve the performance, efficiency, controllability and emissions of a homogeneous charge compression ignition (HCCI) engine. The project team utilized both engine simulation and laboratory testing to evaluate and optimize how blends of hydrogen and natural gas fuel might improve control of HCCI combustion. GTI utilized a state-of-the art single-cylinder engine test platform for the experimental work in the project. The testing was designed to evaluate the feasibility of extending the limits of HCCI engine performance (i.e., stable combustion, high efficiency and low emissions) on natural gas by using blends of natural gas and hydrogen. Early in the project Ricardo provided technical support to GTI as we applied their engine performance simulation program, WAVE, to our HCCI research engine. Modeling support was later provided by Digital Engines, LLC to use their proprietary model to predict peak pressures and temperatures for varying operating parameters included in the Design of Experiments test plan. Digital Engines also provided testing support for the hydrogen and natural gas blends. Prof. David Foster of University of Wisconsin-Madison participated early in the project by providing technical guidance on HCCI engine test plans and modeling requirements. The main purpose of the testing was to quantify the effects of hydrogen addition to natural gas HCCI. Directly comparing straight natural gas with the hydrogen enhanced test points is difficult due to the complexity of HCCI combustion. With the same air flow rate and lambda, the hydrogen enriched fuel mass flow rate is lower than the straight natural gas mass flow rate. However, the energy flow rate is higher for the hydrogen enriched fuel due to hydrogen's significantly greater lower heating value, 120 mJ/kg for hydrogen compared to 45 mJ/kg for natural gas. With these caveats in mind, an

  14. Human health cost of hydrogen sulfide air pollution from an oil and gas Field.

    Science.gov (United States)

    Kenessary, Dinara; Kenessary, Almas; Kenessariyev, Ussen Ismailovich; Juszkiewicz, Konrad; Amrin, Meiram Kazievich; Erzhanova, Aya Eralovna

    2017-06-08

    Introduction and objective. The Karachaganak oil and gas condensate field (KOGCF), one of the largest in the world, located in the Republic of Kazakhstan (RoK) in Central Asia, is surrounded by 10 settlements with a total population of 9,000 people. Approximately73% of this population constantly mention a specific odour of rotten eggs in the air, typical for hydrogen sulfide (H2S) emissions, and the occurrence of low-level concentrations of hydrogen sulfide around certain industrial installations (esp. oil refineries) is a well known fact. Therefore, this study aimed at determining the impact on human health and the economic damage to the country due to H2S emissions. Materials and method. Dose-response dependency between H2S concentrations in the air and cardiovascular morbidity using multiple regression analysis was applied. Economic damage from morbidity was derived with a newly-developed method, with Kazakhstani peculiarities taken into account. Results.Hydrogen sulfide air pollution due to the KOGCF activity costs the state almost $60,000 per year. Moreover, this is the reason for a more than 40% rise incardiovascular morbidity in the region. Conclusion. The reduction of hydrogen sulfide emissions into the air is recommended, as well as successive constant ambient air monitoring in future. Economic damage evaluation should be made mandatory, on a legal basis, whenever an industrial facility operation results in associated air pollution.

  15. Thermodynamic analyses of hydrogen production from sub-quality natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Cunping; T-Raissi, Ali [Florida Solar Energy Center, University of Central Florida, 1679 Clearlake Road, Cocoa, FL 32922-5403 (United States)

    2007-01-01

    Part I of this paper analyzed sub-quality natural gas (SQNG) pyrolysis and autothermal pyrolysis. Production of hydrogen via direct thermolysis of SQNGs produces only 2mol of hydrogen and 1mol of carbon per mole of methane (CH{sub 4}). Steam reforming of SQNG (SRSQNG) could become a more effective approach because the processes produce two more moles of hydrogen via water splitting. A Gibbs reactor unit operation in the AspenPlus(TM) chemical process simulator was employed to accomplish equilibrium calculations for the SQNG+H{sub 2}O and SQNG+H{sub 2}O+O{sub 2} systems. The results indicate that water and oxygen inlet flow rates do not significantly affect the decomposition of hydrogen sulfide (H{sub 2}S) at temperatures lower than 1000{sup o}C. The major co-product of the processes is carbonyl sulfide (COS) while sulfur dimer (S{sub 2}) and carbon disulfide (CS{sub 2}) are minor by-products within this temperature range. At higher temperatures (>1300{sup o}C), CS{sub 2} and S{sub 2} become major co-products. No sulfur dioxide (SO{sub 2}) or sulfur trioxide (SO{sub 3}) is formed during either SRSQNG or autothermal SRSQNG processes, indicating that no environmentally harmful acidic gases are generated. (author)

  16. Multi-level computational chemistry study on hydrogen recombination catalyst of off-gas treatment system

    International Nuclear Information System (INIS)

    Hatakeyama, Nozomu; Ise, Mariko; Inaba, Kenji

    2011-01-01

    In order to reveal the deactivation mechanism of the hydrogen recombination catalyst of off-gas treatment system, we investigate by using multi-level computational chemistry simulation methods. The recombiner apparatus is modeled by the numerical mesh system in the axial coordinates, and unsteady, advection and reaction rate equations are solved by using a finite difference method. The chemical reactions are formulated to represent adsorption-desorption of hydrogen and oxygen on Pt catalyst, and time developments of the coverage factors of Pt are solved numerically. The computational simulations successfully reproduce the very similar behaviors observed by experiments, such as increasing of the inversion rates of H 2 to H 2 O, the temperatures distributions along the flow direction, dependencies of experimental condition, and so on. Thus Pt poisoning is considered to cause the deactivation of the hydrogen recombination catalyst. To clarify the poisoning mechanism, the molecular level simulation is applied to the system of Pt on boehmite attacked by a cyclic siloxane which has been detected by experiments and considered as one of poisoning spices. The simulation shows ring-opening reaction of the cyclic siloxane on Pt, then attachment of two ends of the chain-like siloxane to Pt and boehmite, respectively, and that finally the recombination reaction is prevented. This may be the first study to find out the detailed dynamical mechanism of hydrogen recombination catalyst poisoning with cyclic siloxane. (author)

  17. Co-pyrolysis of coal with hydrogen-rich gases. 1. Coal pyrolysis under coke-oven gas and synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Liao, H.; Li, B.; Zhang, B. [Chinese Academy of Sciences, Taiyuan (China). State Key Lab. of Coal Conversion

    1998-06-01

    To improve the economics of the hydropyrolysis process, it has been suggested that cheaper hydrogen-rich gases (such as coke oven gas, synthesis gas) could be used instead of pure hydrogen. Pyrolysis of Chinese Xianfeng lignite was carried out with coke oven gas (COG) and synthesis gas (SG) as reactive gases at 0.1-5 MPa and at a final temperature up to 650{degree}C with a heating rate of 5-25{degree}C min{sup -1} in a 10 g fixed-bed reactor. The results indicate that it is possible to use COG and SG instead of pure hydrogen in hydropyrolysis, but that the experimental conditions must be adjusted to optimize the yields of the valuable chemicals. 14 refs., 3 figs., 6 tabs.

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

    Energy Technology Data Exchange (ETDEWEB)

    Alcala Ruiz, F

    1984-07-01

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

  19. Optimization Study of Hydrogen Gas Adsorption on Zig-zag Single-walled Carbon Nanotubes: The Artificial Neural Network Analysis

    Science.gov (United States)

    Nasruddin; Lestari, M.; Supriyadi; Sholahudin

    2018-03-01

    The use of hydrogen gas in fuel cell technology has a huge opportunity to be applied in upcoming vehicle technology. One of the most important problems in fuel cell technology is the hydrogen storage. The adsorption of hydrogen in carbon-based materials attracts a lot of attention because of its reliability. This study investigated the adsorption of hydrogen gas in Single-walled Carbon Nano Tubes (SWCNT) with chilarity of (0, 12), (0, 15), and (0, 18) to find the optimum chilarity. Artificial Neural Networks (ANN) can be used to predict the hydrogen storage capacity at different pressure and temperature conditions appropriately, using simulated series of data. The Artificial Neural Network is modeled as a predictor of the hydrogen adsorption capacity which provides solutions to some deficiencies in molecular dynamics (MD) simulations. In a previous study, ANN configurations have been developed for 77k, 233k, and 298k temperatures in hydrogen gas storage. To prepare this prediction, ANN is modeled to find out the configurations that exist in the set of training and validation of specified data selection, the distance between data, and the number of neurons that produce the smallest error. This configuration is needed to make an accurate artificial neural network. The configuration of neural network was then applied to this research. The neural network analysis results show that the best configuration of artificial neural network in hydrogen storage is at 233K temperature i.e. on SWCNT with chilarity of (0.12).

  20. Improved Hydrogen Gas Getters for TRU Waste Transuranic and Mixed Waste Focus Area - Phase 2 Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Mark Lee

    2002-04-01

    Alpha radiolysis of hydrogenous waste and packaging materials generates hydrogen gas in radioactive storage containers. For that reason, the Nuclear Regulatory Commission (NRC) limits the flammable gas (hydrogen) concentration in the Transuranic Package Transporter-II (TRUPACT-II) containers to 5 vol% of hydrogen in air, which is the lower explosion limit. Consequently, a method is needed to prevent the build up of hydrogen to 5 vol% during the storage and transport of the TRUPACT-II containers (up to 60 days). One promising option is the use of hydrogen getters. These materials scavenge hydrogen from the gas phase and irreversibly bind it in the solid phase. One proven getter is a material called 1,4-bis (phenylethynyl) benzene, or DEB. It has the needed binding rate and capacity, but some of the chemical species that might be present in the containers could interfere with its ability to remove hydrogen. This project is focused upon developing a protective polymeric membrane coating for the DEB getter material, which comes in the form of small, irregularly shaped particles. This report summarizes the experimental results of the second phase of the development of the materials.

  1. The hydrogen generated as a gas and storage in Zircaloy during water quenching

    International Nuclear Information System (INIS)

    Garcia, Eduardo A.

    1999-01-01

    A simple one-dimensional diffusion model has been developed for the complex process of Zircaloy oxidation during water quenching, calculating the hydrogen liberated as a gas and the hydrogen stored in the metal. The model was developed on the basis of small-scale separate-effects quench experiments performed at Forschungszentrum Karlsruhe. The new oxide surface and the new metallic surface produced by cracking of the oxide during quenching are calculated for each experiment performed at 1200 , 1400 and 1600 C degrees using as-received Zircaloy-4 (no pre oxidation) and with Zircaloy specimens pre oxidised to give oxide thicknesses of 100μm and 300μm. The results are relevant to accident management in light water reactors. (author)

  2. Durable regenerable sorbent pellets for removal of hydrogen sulfide coal gas

    Science.gov (United States)

    Siriwardane, Ranjani V.

    1999-01-01

    Pellets for removing hydrogen sulfide from a coal gasification stream at an elevated temperature are prepared in durable form, usable over repeated cycles of absorption and regeneration. The pellets include a material reactive with hydrogen sulfide, in particular zinc oxide, a binder, and an inert material, in particular calcium sulfate (drierite), having a particle size substantially larger than other components of the pellets. A second inert material and a promoter may also be included. Preparation of the pellets may be carried out by dry, solid-state mixing of components, moistening the mixture, and agglomerating it into pellets, followed by drying and calcining. Pellet size is selected, depending on the type of reaction bed for which the pellets are intended. The use of inert material with a large particle size provides a stable pellet structure with increased porosity, enabling effective gas contact and prolonged mechanical durability.

  3. Durable regenerable sorbent pellets for removal of hydrogen sulfide from coal gas

    Science.gov (United States)

    Siriwardane, Ranjani V.

    1997-01-01

    Pellets for removing hydrogen sulfide from a coal gasification stream at an elevated temperature are prepared in durable form usable over repeated cycles of absorption and regeneration. The pellets include a material reactive with hydrogen sulfide, in particular zinc oxide, a binder, and an inert material, in particular calcium sulfate (drierite), having a particle size substantially larger than other components of the pellets. A second inert material and a promoter may also be included. Preparation of the pellets may be carried out by dry, solid-state mixing of components, moistening the mixture, and agglomerating it into pellets, followed by drying and calcining. Pellet size is selected, depending on the type of reaction bed for which the pellets are intended. The use of inert material with a large particle size provides a stable pellet structure with increased porosity, enabling effective gas contact and prolonged mechanical durability.

  4. Evaluation of the plasma hydrogen isotope content by residual gas analysis at JET and AUG

    Science.gov (United States)

    Drenik, A.; Alegre, D.; Brezinsek, S.; De Castro, A.; Kruezi, U.; Oberkofler, M.; Panjan, M.; Primc, G.; Reichbauer, T.; Resnik, M.; Rohde, V.; Seibt, M.; Schneider, P. A.; Wauters, T.; Zaplotnik, R.; ASDEX-Upgrade, the; EUROfusion MST1 Teams; contributors, JET

    2017-12-01

    The isotope content of the plasma reflects on the dynamics of isotope changeover experiments, efficiency of wall conditioning and the performance of a fusion device in the active phase of operation. The assessment of the isotope ratio of hydrogen and methane molecules is used as a novel method of assessing the plasma isotope ratios at JET and ASDEX-Upgrade (AUG). The isotope ratios of both molecules in general shows similar trends as the isotope ratio detected by other diagnostics. At JET, the absolute values of RGA signals are in relatively good agreement with each other and with spectroscopy data, while at AUG the deviation from neutral particle analyser data are larger, and the results show a consistent spatial distribution of the isotope ratio. It is further shown that the isotope ratio of the hydrogen molecule can be used to study the degree of dissociation of the injected gas during changeover experiments.

  5. Gas-phase Hydrogenation of Crotonaldehyde Over Nickel-on-Kieselguhr Catalyst Pellets

    International Nuclear Information System (INIS)

    Uraz, C.; Atalay, F.; Atalay, S.

    2001-01-01

    Gas phase catalytic hydrogenation of crotonaldehyde to η-butanol was investigated. A nickel based commercial catalyst produced by Harshaw was used at constant temperatures ranging from 160 to 210deg; at pressures of 1.5, 2 , and 2.5 atm and at different crotonaldehyde to hydrogen feed ratios changing from 0.134 to 0.226. The conversion of crotonaldehyde at different operating conditions were determined and the reaction rates were calculated . The experimental results were fitted to ten langmuir-Hinshelwood/ Eley Rideal type models in addition to a homogeneous kinetics modal and the best modal was identified. The effects of external and internal mass transfer resistances were found to be negligible .(authors) refs 28., 2 figs , 4 tabs

  6. The hydrogen generated as a gas and storage in Zircaloy during steam quenching

    International Nuclear Information System (INIS)

    Garcia, Eduardo A.

    2000-01-01

    A simple one-dimensional diffusion model has been developed for the complex process of Zircaloy oxidation during steam quenching, calculating the hydrogen liberated as a gas and the hydrogen stored in the metal. The model was developed on the basis of small-scale separate-effects quench experiments performed at Forschungszentrum Karlsruhe. The new oxide surface and the new metallic surface produced by cracking of the oxide during quenching are calculated for each experiment performed at 1200 centigrade, 1400 centigrade and 1600 centigrade using as-received Zircaloy-4 (no pre-oxidation) and with Zircaloy specimens pre-oxidized to give oxide thickness of 100μm and 300μm. The results are relevant to accident management in nuclear power plants. (author)

  7. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry

    Science.gov (United States)

    Ellis, Wade C.; Lewis, Charlotte R.; Openshaw, Anna P.; Farnsworth, Paul B.

    2016-09-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration.

  8. Study of cycle-by-cycle variations of a spark ignition engine fueled with natural gas-hydrogen blends

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinhua; Chen, Hao; Liu, Bing; Huang, Zuohua [State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

    2008-09-15

    Cycle-by-cycle variations of a spark ignition engine fueled with natural gas-hydrogen blends with hydrogen volumetric fraction of 0%, 12%, 23%, 30% and 40% were studied. The effect of hydrogen addition on cycle-by-cycle variations of the natural gas engine was analyzed. The results showed that the peak cylinder pressure, the maximum rate of pressure rise and the indicated mean effective pressure increased and their corresponding cycle-by-cycle variations decreased with the increase of hydrogen fraction at lean mixture operation. The interdependency between the combustion parameters and the corresponding crank angle tended to be strongly correlated with the increase of hydrogen fraction under lean mixture operation. Coefficient of variation of the indicated mean effective pressure gave a low level and is slightly influenced by hydrogen addition under the stoichiometric and relatively rich mixture operation while it decreased remarkably with the increase of hydrogen fraction under the lean mixture operation. The excessive air ratio at CoV{sub imep} = 10% extended to the leaner mixture side with the increase of hydrogen fraction and this indicated that the engine lean operating limit could be extended with hydrogen addition. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    This project is in response to a requirement for a system that combines water gas shift technology with separation technology for coal derived synthesis gas. The justification of such a system would be improved efficiency for the overall hydrogen production. By removing hydrogen from the synthesis gas stream, the water gas shift equilibrium would force more carbon monoxide to carbon dioxide and maximize the total hydrogen produced. Additional benefit would derive from the reduction in capital cost of plant by the removal of one step in the process by integrating water gas shift with the membrane separation device. The answer turns out to be that the integration of hydrogen separation and water gas shift catalysis is possible and desirable. There are no significant roadblocks to that combination of technologies. The problem becomes one of design and selection of materials to optimize, or at least maximize performance of the two integrated steps. A goal of the project was to investigate the effects of alloying elements on the performance of vanadium membranes with respect to hydrogen flux and fabricability. Vanadium was chosen as a compromise between performance and cost. It is clear that the vanadium alloys for this application can be produced, but the approach is not simple and the results inconsistent. For any future contracts, large single batches of alloy would be obtained and rolled with larger facilities to produce the most consistent thin foils possible. Brazing was identified as a very likely choice for sealing the membranes to structural components. As alloying was beneficial to hydrogen transport, it became important to identify where those alloying elements might be detrimental to brazing. Cataloging positive and negative alloying effects was a significant portion of the initial project work on vanadium alloying. A water gas shift catalyst with ceramic like structural characteristics was the second large goal of the project. Alumina was added as a

  10. A graphite foam reinforced by graphite particles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.J.; Wang, X.Y.; Guo, L.F.; Wang, Y.M.; Wang, Y.P.; Yu, M.F.; Lau, K.T.T. [DongHua University, Shanghai (China). College of Material Science and Engineering

    2007-11-15

    Graphite foam was obtained after carbonization and graphitization of a pitch foam formed by the pyrolysis of coal tar based mesophase pitch mixed with graphite particles in a high pressure and temperature chamber. The graphite foam possessed high mechanical strength and exceptional thermal conductivity after adding the graphite particles. Experimental results showed that the thermal conductivity of modified graphite foam reached 110W/m K, and its compressive strength increased from 3.7 MPa to 12.5 MPa with the addition of 5 wt% graphite particles. Through the microscopic observation, it was also found that fewer micro-cracks were formed in the cell wall of the modified foam as compared with pure graphite foam. The graphitization degree of modified foam reached 84.9% and the ligament of graphite foam exhibited high alignment after carbonization at 1200{sup o}C for 3 h and graphitization at 3000{sup o}C for 10 min.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-01

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

  12. Data acquisition and quantitative analysis of stable hydrogen isotope in liquid and gas in the liquid phase catalytic exchange process

    International Nuclear Information System (INIS)

    Choi, H. J.; Lee, H. S.; Kim, K. R.; Cheong, H. S.; Ahn, D. H.; Lee, S. H.; Paek, S. W.; Kang, H. S.; Kim, J. G.

    2001-01-01

    A pilot plant for the Liquid Phase Catalytic Exchange process was built and has been operating to test the hydrophobic catalyst developed to remove the tritium generated at the CANDU nuclear power plants. The methods of quantitative analysis of hydrogen stable isotope were compared. Infrared spectroscopy was used for the liquid samples, and gas chromatography with hydrogen carrier gas showed the best result for gas samples. Also, a data acquisition system was developed to record the operation parameters. This record was very useful to investigate the causes of the system trip

  13. Preliminary design analysis of hot gas ducts and a intermediate heat exchanger for the nuclear hydrogen reactor

    International Nuclear Information System (INIS)

    Song, K. N.; Kim, Y. W.

    2008-01-01

    Korea Atomic Energy Research Institute (KAERI) is in the process of carrying out a nuclear hydrogen system by considering the indirect cycle gas cooled reactors that produce heat at temperatures in the order of 950 .deg. C. Primary and secondary hot gas ducts with coaxial double tubes and are key components connecting a reactor pressure vessel and a intermediate heat exchanger for the nuclear hydrogen system. In this study, preliminary design analyses on the hot gas ducts and the intermediate heat exchanger were carried out. These preliminary design activities include a preliminary design on the geometric dimensions, a preliminary strength evaluation, thermal sizing, and an appropriate material selection

  14. Accident for natural gas well with hydrogen sulfide in relation to nuclear power plant siting

    International Nuclear Information System (INIS)

    Tan Chengjun; Shangguang Zhihong; Sha Xiangdong

    2010-01-01

    In order to make assessment to the potential impact from accident of natural gas wells with hydrogen sulfide on the habitability of main control room of nuclear power plant (NPP), several assumptions such as source terms of maximum credible accident, conservative atmospheric conditions and release characteristics were proposed in the paper, and the impact on the habitability of main control room was evaluated using toxicity thresholds recommended by foreign authority. Case results indicate that the method can provide the reference for the preliminary assessment to external human-induced events during the siting phrase of NPP. (authors)

  15. Fluorometric method for the determination of gas-phase hydrogen peroxide

    Science.gov (United States)

    Kok, Gregory L.; Lazrus, Allan L.

    1986-01-01

    The fluorometric gas-phase hydrogen peroxide procedure is based on the technique used by Lazrus et. al. for the determination of H2O2 in the liquid phase. The analytical method utilizes the reaction of H2O2 with horseradish peroxidase and p-hydroxphenylacetic acid (POPHA) to form the fluorescent dimer of POPHA. The analytical reaction responds stoichiometrically to both H2O2 and some organic hydroperoxides. To discriminate H2O2 from organic hydroperoxides, catalase is used to preferentially destroy H2O2. Using a dual-channel flow system the H2O2 concentration is determined by difference.

  16. Hydrogen Peroxide and Ozone Formation in Hybrid Gas-Liquid Electrical Discharge Reactors

    Czech Academy of Sciences Publication Activity Database

    Lukeš, Petr; Appleton, A. T.; Locke, B. R.

    2004-01-01

    Roč. 40, č. 1 (2004), s. 60-67 ISSN 0093-9994. [IEEE Industry Applications Society Annual Meeting 2002/37th./. Pittsburgh, Pennsylvania , 13.10.2002-18.10.2002] R&D Projects: GA ČR GA202/02/1026; GA MŠk ME 472 Grant - others:NSF(US) INT0086351 Keywords : hydrogen peroxide, ozone, corona discharge, water treatment, hybrid reactor Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.987, year: 2004

  17. Next Generation Nuclear Plant Phenomena Identification and Ranking Tables (PIRTs) Volume 5: Graphite PIRTs

    International Nuclear Information System (INIS)

    Burchell, Timothy D.; Bratton, Rob; Marsden, Barry; Srinivasan, Makuteswara; Penfield, Scott; Mitchell, Mark; Windes, Will

    2008-01-01

    Here we report the outcome of the application of the Nuclear Regulatory Commission (NRC) Phenomena Identification and Ranking Table (PIRT) process to the issue of nuclear-grade graphite for the moderator and structural components of a next generation nuclear plant (NGNP), considering both routine (normal operation) and postulated accident conditions for the NGNP. The NGNP is assumed to be a modular high-temperature gas-cooled reactor (HTGR), either a gas-turbine modular helium reactor (GTMHR) version (a prismatic-core modular reactor (PMR)] or a pebble-bed modular reactor (PBMR) version (a pebble bed reactor (PBR)] design, with either a direct- or indirect-cycle gas turbine (Brayton cycle) system for electric power production, and an indirect-cycle component for hydrogen production. NGNP design options with a high-pressure steam generator (Rankine cycle) in the primary loop are not considered in this PIRT. This graphite PIRT was conducted in parallel with four other NRC PIRT activities, taking advantage of the relationships and overlaps in subject matter. The graphite PIRT panel identified numerous phenomena, five of which were ranked high importance-low knowledge. A further nine were ranked with high importance and medium knowledge rank. Two phenomena were ranked with medium importance and low knowledge, and a further 14 were ranked medium importance and medium knowledge rank. The last 12 phenomena were ranked with low importance and high knowledge rank (or similar combinations suggesting they have low priority). The ranking/scoring rationale for the reported graphite phenomena is discussed. Much has been learned about the behavior of graphite in reactor environments in the 60-plus years since the first graphite rectors went into service. The extensive list of references in the Bibliography is plainly testament to this fact. Our current knowledge base is well developed. Although data are lacking for the specific grades being considered for Generation IV (Gen IV

  18. Detection of Hydrogen Sulphide Gas Sensor Based Nanostructured Ba2CrMoO6 Thick Films

    Directory of Open Access Journals (Sweden)

    A. V. Kadu

    2007-11-01

    Full Text Available Nanocrystalline pure and doped Ba2CrMoO6, having an average crystallite size of 40 nm were synthesized by the sol-gel citrate method. Structural and gas-sensing characteristics were performed by using X-ray diffraction (XRD and sensitivity measurements. The gas sensing properties to reducing gases like Hydrogen sulphide (H2S, liquefied petroleum gas (LPG, carbon monoxide (CO and hydrogen gas (H2 were also discussed. The maximum sensitivity was obtained for 5 wt % Ni doped Ba2CrMoO6 at an operating temperature 250oC for H2S gas. Pd incorporation over 5 wt% Ni doped Ba2CrMoO6 improved the sensitivity, selectivity, response time, and reduced the operating temperature from 250 to 200oC of the sensor for H2S gas. This sensor also shows good satiability.

  19. Uranium Oxide Aerosol Transport in Porous Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, Jeremy; Gerlach, David C.; Scheele, Randall D.; Stewart, Mark L.; Reid, Bruce D.; Gauglitz, Phillip A.; Bagaasen, Larry M.; Brown, Charles C.; Iovin, Cristian; Delegard, Calvin H.; Zelenyuk, Alla; Buck, Edgar C.; Riley, Brian J.; Burns, Carolyn A.

    2012-01-23

    The objective of this paper is to investigate the transport of uranium oxide particles that may be present in carbon dioxide (CO2) gas coolant, into the graphite blocks of gas-cooled, graphite moderated reactors. The transport of uranium oxide in the coolant system, and subsequent deposition of this material in the graphite, of such reactors is of interest because it has the potential to influence the application of the Graphite Isotope Ratio Method (GIRM). The GIRM is a technology that has been developed to validate the declared operation of graphite moderated reactors. GIRM exploits isotopic ratio changes that occur in the impurity elements present in the graphite to infer cumulative exposure and hence the reactor’s lifetime cumulative plutonium production. Reference Gesh, et. al., for a more complete discussion on the GIRM technology.

  20. Potential for greenhouse gas emission reductions using surplus electricity in hydrogen, methane and methanol production via electrolysis

    International Nuclear Information System (INIS)

    Uusitalo, Ville; Väisänen, Sanni; Inkeri, Eero; Soukka, Risto

    2017-01-01

    Highlights: • Greenhouse gas emission reductions using power-to-x processes are studied using life cycle assessment. • Surplus electricity use led to greenhouse gas emission reductions in all studied cases. • Highest reductions can be achieved by using hydrogen to replace fossil based hydrogen. • High reductions are also achieved when fossil transportation fuels are replaced. - Abstract: Using a life cycle perspective, potentials for greenhouse gas emission reductions using various power-to-x processes via electrolysis have been compared. Because of increasing renewable electricity production, occasionally surplus renewable electricity is produced, which leads to situations where the price of electricity approach zero. This surplus electricity can be used in hydrogen, methane and methanol production via electrolysis and other additional processes. Life cycle assessments have been utilized to compare these options in terms of greenhouse gas emission reductions. All of the power-to-x options studied lead to greenhouse gas emission reductions as compared to conventional production processes based on fossil fuels. The highest greenhouse gas emission reductions can be gained when hydrogen from steam reforming is replaced by hydrogen from the power-to-x process. High greenhouse gas emission reductions can also be achieved when power-to-x products are utilized as an energy source for transportation, replacing fossil transportation fuels. A third option with high greenhouse gas emission reduction potential is methane production, storing and electricity conversion in gas engines during peak consumption hours. It is concluded that the power-to-x processes provide a good potential solution for reducing greenhouse gas emissions in various sectors.

  1. Preliminary Conceptual Design and Development of Core Technology of Very High Temperature Gas-Cooled Reactor Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jong Hwa; Kang, H. S.; Gil, C. S. and others

    2006-05-15

    For the nuclear hydrogen production system, the VHTR technology and the IS cycle technology are being developed. A comparative evaluation on the block type reactor and the pebble type reactor is performed to decide a proper nuclear hydrogen production reactor. 100MWt prismatic type reactor is tentatively decided and its safety characteristics are roughly investigated. Computation codes of nuclear design, thermo-fluid design, safety-performance analysis are developed and verified. Also, the development of a risk informed design technology is started. Experiments for metallic materials and graphites are carried out for the selection of materials of VHTR components. Diverse materials for process heat exchanger are studied in various corrosive environments. Pyrolytic carbon and SiC coating technology is developed and fuel manufacturing technology is basically established. Computer program is developed to evaluate the performance of coated particle fuels.

  2. Preliminary Conceptual Design and Development of Core Technology of Very High Temperature Gas-Cooled Reactor Hydrogen Production

    International Nuclear Information System (INIS)

    Chang, Jong Hwa; Kang, H. S.; Gil, C. S. and others

    2006-05-01

    For the nuclear hydrogen production system, the VHTR technology and the IS cycle technology are being developed. A comparative evaluation on the block type reactor and the pebble type reactor is performed to decide a proper nuclear hydrogen production reactor. 100MWt prismatic type reactor is tentatively decided and its safety characteristics are roughly investigated. Computation codes of nuclear design, thermo-fluid design, safety-performance analysis are developed and verified. Also, the development of a risk informed design technology is started. Experiments for metallic materials and graphites are carried out for the selection of materials of VHTR components. Diverse materials for process heat exchanger are studied in various corrosive environments. Pyrolytic carbon and SiC coating technology is developed and fuel manufacturing technology is basically established. Computer program is developed to evaluate the performance of coated particle fuels

  3. Conversion rate of para-hydrogen to ortho-hydrogen by oxygen: implications for PHIP gas storage and utilization.

    Science.gov (United States)

    Wagner, Shawn

    2014-06-01

    To determine the storability of para-hydrogen before reestablishment of the room temperature thermal equilibrium mixture. Para-hydrogen was produced at near 100% purity and mixed with different oxygen quantities to determine the rate of conversion to the thermal equilibrium mixture of 75: 25% (ortho: para) by detecting the ortho-hydrogen (1)H nuclear magnetic resonance using a 9.4 T imager. The para-hydrogen to ortho-hydrogen velocity constant, k, near room temperature (292 K) was determined to be 8.27 ± 1.30 L/mol · min(-1). This value was calculated utilizing four different oxygen fractions. Para-hydrogen conversion to ortho-hydrogen by oxygen can be minimized for long term storage with judicious removal of oxygen contamination. Prior calculated velocity rates were confirmed demonstrating a dependence on only the oxygen concentration.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-29

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

  6. Hydrogen production by high-temperature gas-cooled reactor. Conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system

    International Nuclear Information System (INIS)

    Sakaba, Nariaki; Ohashi, Hirofumi; Sato, Hiroyuki; Hara, Teruo; Kato, Ryoma; Kunitomi, Kazuhiko

    2008-01-01

    Nuclear hydrogen production is necessary in an anticipated hydrogen society that demands a massive quantity of hydrogen without economic disadvantage. Japan Atomic Energy Agency (JAEA) has launched the conceptual design study of a hydrogen production system with a near-term plan to connect it to Japan's first high-temperature gas-cooled reactor HTTR. The candidate hydrogen production system is based on the thermochemical water-splitting iodine sulphur (IS) process.The heat of 10 MWth at approximately 900degC, which can be provided by the secondary helium from the intermediate heat exchanger of the HTTR, is the energy input to the hydrogen production system. In this paper, we describe the recent progresses made in the conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system. A new concept of sulphuric acid decomposer is proposed. This involves the integration of three separate functions of sulphuric acid decomposer, sulphur trioxide decomposer, and process heat exchanger. A new mixer-settler type of Bunsen reactor is also designed. This integrates three separate functions of Bunsen reactor, phase separator, and pump. The new concepts are expected to result in improved economics through construction and operation cost reductions because the number of process equipment and complicated connections between the equipment has been substantially reduced. (author)

  7. Thermal detection mechanism of SiC based hydrogen resistive gas sensors

    Science.gov (United States)

    Fawcett, Timothy J.; Wolan, John T.; Lloyd Spetz, Anita; Reyes, Meralys; Saddow, Stephen E.

    2006-10-01

    Silicon carbide (SiC) resistive hydrogen gas sensors have been fabricated and tested. Planar NiCr contacts were deposited on a thin 3C-SiC epitaxial film grown on thin Si wafers bonded to polycrystalline SiC substrates. At 673K, up to a 51.75±0.04% change in sensor output current and a change in the device temperature of up to 163.1±0.4K were demonstrated in response to 100% H2 in N2. Changes in device temperature are shown to be driven by the transfer of heat from the device to the gas, giving rise to a thermal detection mechanism.

  8. Gas generation from radiolytic attack of TRU-contaminated hydrogenous waste

    International Nuclear Information System (INIS)

    Zerwekh, A.

    1979-06-01

    In 1970, the Waste Management and Transportation Division of the Atomic Energy Commission ordered a segregation of transuranic (TRU)-contaminated solid wastes. Those below a contamination level of 10 nCi/g could still be buried; those above had to be stored retrievably for 20 y. The possibility that alpha-radiolysis of hydrogenous materials might produce toxic, corrosive, and flammable gases in retrievably stored waste prompted an investigation of gas identities and generation rates in the laboratory and field. Typical waste mixtures were synthesized and contaminated for laboratory experiments, and drums of actual TRU-contaminated waste were instrumented for field testing. Several levels of contamination were studied, as well as pressure, temperature, and moisture effects. G (gas) values were determined for various waste matrices, and degradation products were examined

  9. Ground state of a hydrogen ion molecule immersed in an inhomogeneous electron gas

    International Nuclear Information System (INIS)

    Diaz-Valdes, J.; Gutierrez, F.A.; Matamala, A.R.; Denton, C.D.; Vargas, P.; Valdes, J.E.

    2007-01-01

    In this work we have calculated the ground state energy of the hydrogen molecule, H 2 + , immersed in the highly inhomogeneous electron gas around a metallic surface within the local density approximation. The molecule is perturbed by the electron density of a crystalline surface of Au with the internuclear axis parallel to the surface. The surface spatial electron density is calculated through a linearized band structure method (LMTO-DFT). The ground state of the molecule-ion was calculated using the Born-Oppenheimer approximation for a fixed-ion while the screening effects of the inhomogeneous electron gas are depicted by a Thomas-Fermi like electrostatic potential. We found that within our model the molecular ion dissociates at the critical distance of 2.35a.u. from the first atomic layer of the solid

  10. Membrane steam reforming of natural gas for hydrogen production by utilization of medium temperature nuclear reactor

    International Nuclear Information System (INIS)

    Djati Hoesen Salimy

    2010-01-01

    The assessment of steam reforming process with membrane reactor for hydrogen production by utilizing of medium temperature nuclear reactor has been carried out. Difference with the conventional process of natural gas steam reforming that operates at high temperature (800-1000°C), the process with membrane reactor operates at lower temperature (~500°C). This condition is possible because the use of perm-selective membrane that separate product simultaneously in reactor, drive the optimum conversion at the lower temperature. Besides that, membrane reactor also acts the role of separation unit, so the plant will be more compact. From the point of nuclear heat utilization, the low temperature of process opens the chance of medium temperature nuclear reactor utilization as heat source. Couple the medium temperature nuclear reactor with the process give the advantage from the point of saving fossil fuel that give direct implication of decreasing green house gas emission. (author)

  11. Evaluation of Technical Feasibility of Homogeneous Charge Compression Ignition (HCCI) Engine Fueled with Hydrogen, Natural Gas, and DME

    Energy Technology Data Exchange (ETDEWEB)

    Pratapas, John; Mather, Daniel; Kozlovsky, Anton

    2013-03-31

    The objective of the proposed project was to confirm the feasibility of using blends of hydrogen and natural gas to improve the performance, efficiency, controllability and emissions of a homogeneous charge compression ignition (HCCI) engine. The project team utilized both engine simulation and laboratory testing to evaluate and optimize how blends of hydrogen and natural gas fuel might improve control of HCCI combustion. GTI utilized a state-of-the art single-cylinder engine test platform for the experimental work in the project. The testing was designed to evaluate the feasibility of extending the limits of HCCI engine performance (i.e., stable combustion, high efficiency and low emissions) on natural gas by using blends of natural gas and hydrogen. Early in the project Ricardo provided technical support to GTI as we applied their engine performance simulation program, WAVE, to our HCCI research engine. Modeling support was later provided by Digital Engines, LLC to use their proprietary model to predict peak pressures and temperatures for varying operating parameters included in the Design of Experiments test plan. Digital Engines also provided testing support for the hydrogen and natural gas blends. Prof. David Foster of University of Wisconsin-Madison participated early in the project by providing technical guidance on HCCI engine test plans and modeling requirements. The main purpose of the testing was to quantify the effects of hydrogen addition to natural gas HCCI. Directly comparing straight natural gas with the hydrogen enhanced test points is difficult due to the complexity of HCCI combustion. With the same air flow rate and lambda, the hydrogen enriched fuel mass flow rate is lower than the straight natural gas mass flow rate. However, the energy flow rate is higher for the hydrogen enriched fuel due to hydrogen’s significantly greater lower heating value, 120 mJ/kg for hydrogen compared to 45 mJ/kg for natural gas. With these caveats in mind, an

  12. Greenhouse gas reduction benefits and costs of a large-scale transition to hydrogen in the USA

    International Nuclear Information System (INIS)

    Dougherty, William; Kartha, Sivan; Lazarus, Michael; Fencl, Amanda; Rajan, Chella; Bailie, Alison; Runkle, Benjamin

    2009-01-01

    Hydrogen is an energy carrier able to be produced from domestic, zero-carbon sources and consumed by zero-pollution devices. A transition to a hydrogen-based economy could therefore potentially respond to climate, air quality, and energy security concerns. In a hydrogen economy, both mobile and stationary energy needs could be met through the reaction of hydrogen (H 2 ) with oxygen (O 2 ). This study applies a full fuel cycle approach to quantify the energy, greenhouse gas emissions (GHGs), and cost implications associated with a large transition to hydrogen in the United States. It explores a national and four metropolitan area transitions in two contrasting policy contexts: a 'business-as-usual' (BAU) context with continued reliance on fossil fuels, and a 'GHG-constrained' context with policies aimed at reducing greenhouse gas emissions. A transition in either policy context faces serious challenges, foremost among them from the highly inertial investments over the past century or so in technology and infrastructure based on petroleum, natural gas, and coal. A hydrogen transition in the USA could contribute to an effective response to climate change by helping to achieve deep reductions in GHG emissions by mid-century across all sectors of the economy; however, these reductions depend on the use of hydrogen to exploit clean, zero-carbon energy supply options. (author)

  13. Greenhouse gas reduction benefits and costs of a large-scale transition to hydrogen in the USA

    Energy Technology Data Exchange (ETDEWEB)

    Dougherty, William; Kartha, Sivan; Lazarus, Michael; Fencl, Amanda [Stockholm Environment Institute - US Center, 11 Curtis Avenue, Somerville, MA 02143 (United States); Rajan, Chella [Indian Institute of Technology Madras, I.I.T. Post Office, Chennai 600 036 (India); Bailie, Alison [The Pembina Institute, 200, 608 - 7th Street, S.W. Calgary, AB (Canada); Runkle, Benjamin [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2009-01-15

    Hydrogen is an energy carrier able to be produced from domestic, zero-carbon sources and consumed by zero-pollution devices. A transition to a hydrogen-based economy could therefore potentially respond to climate, air quality, and energy security concerns. In a hydrogen economy, both mobile and stationary energy needs could be met through the reaction of hydrogen (H{sub 2}) with oxygen (O{sub 2}). This study applies a full fuel cycle approach to quantify the energy, greenhouse gas emissions (GHGs), and cost implications associated with a large transition to hydrogen in the United States. It explores a national and four metropolitan area transitions in two contrasting policy contexts: a 'business-as-usual' (BAU) context with continued reliance on fossil fuels, and a 'GHG-constrained' context with policies aimed at reducing greenhouse gas emissions. A transition in either policy context faces serious challenges, foremost among them from the highly inertial investments over the past century or so in technology and infrastructure based on petroleum, natural gas, and coal. A hydrogen transition in the USA could contribute to an effective response to climate change by helping to achieve deep reductions in GHG emissions by mid-century across all sectors of the economy; however, these reductions depend on the use of hydrogen to exploit clean, zero-carbon energy supply options. (author)

  14. Highly sensitive work function hydrogen gas sensor based on PdNPs/SiO2/Si structure at room temperature

    Directory of Open Access Journals (Sweden)

    G. Behzadi pour

    Full Text Available In this study, fabrication of highly sensitive PdNPs/SiO2/Si hydrogen gas sensor using experimental and theoretical methods has been investigated. Using chemical method the PdNPs are synthesized and characterized by X-ray diffraction (XRD. The average size of PdNPs is 11 nm. The thickness of the oxide film was 20 nm and the surface of oxide film analyzed using Atomic-force microscopy (AFM. The C-V curve for the PdNPs/SiO2/Si hydrogen gas sensor in 1% hydrogen concentration and at the room temperature has been reported. The response time and recovery time for 1% hydrogen concentration at room temperature were 1.2 s and 10 s respectively. The response (R% for PdNPs/SiO2/Si MOS capacitor hydrogen sensor was 96%. The PdNPs/SiO2/Si MOS capacitor hydrogen sensor showed very fast response and recovery times compared to SWCNTs/PdNPs, graphene/PdNPs, nanorod/PdNPs and nanowire/PdNPs hydrogen gas sensors. Keywords: Sensitive, Oxide film, Capacitive, Resistance

  15. Baking and helium glow discharge cleaning of SST-1 tokamak with graphite plasma facing components

    International Nuclear Information System (INIS)

    Semwal, Pratibha; Khan, Ziauddin; Raval, Dilip

    2015-01-01

    Graphite plasma facing components (PFCs) were installed inside SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 X 10 -5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium (He) glow discharge cleaning (GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nanometers from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.48. In this paper, the results of effect of baking and He-GDC experiments of SST-1 will be presented in detail. (author)

  16. Baking and helium glow discharge cleaning of SST-1 Tokamak with graphite plasma facing components

    International Nuclear Information System (INIS)

    Semwal, P; Khan, Z; Raval, D C; Dhanani, K R; George, S; Paravastu, Y; Prakash, A; Thankey, P; Ramesh, G; Khan, M S; Saikia, P; Pradhan, S

    2017-01-01

    Graphite plasma facing components (PFCs) were installed inside the SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 × 10 -5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of this water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium glow discharge cleaning (He-GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nano-meters from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.24. In this paper the results of baking and He-GDC experiments of SST-1 will be presented in detail. (paper)

  17. Baking and helium glow discharge cleaning of SST-1 Tokamak with graphite plasma facing components

    Science.gov (United States)

    Semwal, P.; Khan, Z.; Raval, D. C.; Dhanani, K. R.; George, S.; Paravastu, Y.; Prakash, A.; Thankey, P.; Ramesh, G.; Khan, M. S.; Saikia, P.; Pradhan, S.

    2017-04-01

    Graphite plasma facing components (PFCs) were installed inside the SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 × 10-5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of this water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium glow discharge cleaning (He-GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nano-meters from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.24. In this paper the results of baking and He-GDC experiments of SST-1 will be presented in detail.

  18. Red soil as a regenerable sorbent for high temperature removal of hydrogen sulfide from coal gas

    International Nuclear Information System (INIS)

    Ko, T.-H.; Chu Hsin; Lin, H.-P.; Peng, C.-Y.

    2006-01-01

    In this study, hydrogen sulfide (H 2 S) was removed from coal gas by red soil under high temperature in a fixed-bed reactor. Red soil powders were collected from the northern, center and southern of Taiwan. They were characterized by XRPD, porosity analysis and DCB chemical analysis. Results show that the greater sulfur content of LP red soils is attributed to the higher free iron oxides and suitable sulfidation temperature is around 773 K. High temperature has a negative effect for use red soil as a desulfurization sorbent due to thermodynamic limitation in a reduction atmosphere. During 10 cycles of regeneration, after the first cycle the red soil remained stable with a breakthrough time between 31 and 36 min. Hydrogen adversely affects sulfidation reaction, whereas CO exhibits a positive effect due to a water-shift reaction. COS was formed during the sulfidation stage and this was attributed to the reaction of H 2 S and CO. Results of XRPD indicated that, hematite is the dominant active species in fresh red soil and iron sulfide (FeS) is a product of the reaction between hematite and hydrogen sulfide in red soils. The spinel phase FeAl 2 O 4 was found during regeneration, moreover, the amount of free iron oxides decreased after regeneration indicating the some of the free iron oxide formed a spinel phase, further reducting the overall desulfurization efficiency

  19. Effects of hydrogen gas on properties of tin-doped indium oxide films deposited by radio frequency magnetron sputtering method

    International Nuclear Information System (INIS)

    Kim, Do-Geun; Lee, Sunghun; Lee, Gun-Hwan; Kwon, Sik-Chol

    2007-01-01

    Tin-doped indium oxide (ITO) films were deposited at ∼ 70 deg. C of substrate temperature by radio frequency magnetron sputtering method using an In 2 O 3 -10% SnO 2 target. The effect of hydrogen gas ratio [H 2 / (H 2 + Ar)] on the electrical, optical and mechanical properties was investigated. With increasing the amount of hydrogen gas, the resistivity of the samples showed the lowest value of 3.5 x 10 -4 Ω.cm at the range of 0.8-1.7% of hydrogen gas ratio, while the resistivity increases over than 2.5% of hydrogen gas ratio. Hall effect measurements explained that carrier concentration and its mobility are strongly related with the resistivity of ITO films. The supplement of hydrogen gas also reduced the residual stress of ITO films up to the stress level of 110 MPa. The surface roughness and the crystallinity of the samples were investigated by using atomic force microscopy and x-ray diffraction, respectively

  20. Graphite oxidation in HTGR atmosphere

    International Nuclear Information System (INIS)

    Growcock, F.B.; Barry, J.J.; Finfrock, C.C.; Rivera, E.; Heiser, J.H. III

    1982-01-01

    On-going and recently completed studies of the effect of thermal oxidation on the structural integrity of HTGR candidate graphites are described, and some results are presented and discussed. This work includes the study of graphite properties which may play decisive roles in the graphites' resistance to oxidation and fracture: pore size distribution, specific surface area and impurity distribution. Studies of strength loss mechanisms in addition to normal oxidation are described. Emphasis is placed on investigations of the gas permeability of HTGR graphites and the surface burnoff phenomenon observed during recent density profile measurements. The recently completed studies of catalytic pitting and the effects of prestress and stress on reactivity and ultimate strength are also discussed

  1. Graphite materials for nuclear reactors

    International Nuclear Information System (INIS)

    Oku, Tatsuo

    1991-01-01

    Graphite materials have been used in the nuclear fission reactors from the beginning of the reactor development for the speed reduction and reflection of neutron. Graphite materials are used both as a moderator and as a reflector in the core of high temperature gas-cooled reactors, and both as a radiation shielding material and as a reflector in the surrounding of the core for the fast breeder reactor. On the other hand, graphite materials are being positively used as a first wall of plasma as it is known that low Z materials are useful for holding high temperature plasma in the nuclear fusion devices. In this paper the present status of the application of graphite materials to the nuclear fission reactors and fusion devices (reactors) is presented. In addition, a part of results on the related properties to the structural design and safety evaluation and results examined on the subjects that should be done in the future are also described. (author)

  2. Development of a biofiltration system to remove hydrogen sulphide from small oil and gas production facilities

    International Nuclear Information System (INIS)

    Dombroski, E.C.; Gaudet, I. D.; Coleman, R. N.

    1997-01-01

    Environmental regulations require sulphur separation in any processing operation that produces more than one tonne of sulphur per day. This leaves about 50 small operations in Alberta where the daily production of sulphur is less than one tonne. In these cases, the extracted acid gases are usually flared. Since flares are often inefficient and do not completely oxidize the hydrogen sulfide, an alternate, cost-effective technology that could replace flaring and eliminate atmospheric discharge would be of considerable interest. Biofiltration is known to be capable of oxidizing hydrogen sulfide in an air stream to non-volatile sulphate. The objective of this paper was to investigate the effectiveness of this technology in controlling H 2 S and SO 2 emissions from sour gas plants. Results of this laboratory-scale experiment were encouraging, justifying further studies on a demonstration-scale to determine if a full-scale biofilter could provide a practical, cost-effective technology for sulfur emission control from gas plants. 9 refs., 7 figs

  3. Hydrogen discharges operating at atmospheric pressure in a semiconductor gas discharge system

    Energy Technology Data Exchange (ETDEWEB)

    Aktas, K; Acar, S; Salamov, B G [Physics Department, Faculty of Arts and Sciences, Gazi University, 06500 Ankara (Turkey)

    2011-08-15

    Analyses of physical processes which initiate electrical breakdown and spatial stabilization of current and control it with a photosensitive cathode in a semiconductor gas discharge system (SGDS) are carried out in a wide pressure range up to atmospheric pressure p, interelectrode distance d and diameter D of the electrode areas of the semiconductor cathode. The study compares the breakdown and stability curves of the gas discharge in the planar SGDS where the discharge gap is filled with hydrogen and air in two cases. The impact of the ionizing component of the discharge plasma on the control of the stable operation of the planar SGDS is also investigated at atmospheric pressure. The loss of stability is primarily due to modification of the semiconductor-cathode properties on the interaction with low-energy hydrogen ions and the formation of a space charge of positive ions in the discharge gap which changes the discharge from Townsend to glow type. The experimental results show that the discharge current in H{sub 2} is more stable than in air. The breakdown voltages are measured for H{sub 2} and air with parallel-plane electrodes, for pressures between 28 and 760 Torr. The effective secondary electron emission (SEE) coefficient is then determined from the breakdown voltage results and compared with the experimental results. The influence of the SEE coefficient is stated in terms of the differences between the experimental breakdown law.

  4. Hydrogen-rich gas production by cogasification of coal and biomass in an intermittent fluidized bed.

    Science.gov (United States)

    Wang, Li-Qun; Chen, Zhao-Sheng

    2013-01-01

    This paper presents the experimental results of cogasification of coal and biomass in an intermittent fluidized bed reactor, aiming to investigate the influences of operation parameters such as gasification temperature (T), steam to biomass mass ratio (SBMR), and biomass to coal mass ratio (BCMR) on hydrogen-rich (H2-rich) gas production. The results show that H2-rich gas free of N2 dilution is produced and the H2 yield is in the range of 18.25~68.13 g/kg. The increases of T, SBMR, and BCMR are all favorable for promoting the H2 production. Higher temperature contributes to higher CO and H2 contents, as well as H2 yield. The BCMR has a weak influence on gas composition, but the yield and content of H2 increase with BCMR, reaching a peak at the BCMR of 4. The H2 content and yield in the product gas increase with SBMR, whilst the content of CO increases first and then decreases correspondingly. At a typical case, the relative linear sensitivity coefficients of H2 production efficiency to T, SBMR, and BCMR were calculated. The results reveal that the order of the influence of the operation parameters on H2 production efficiency is T > SBMR > BCMR.

  5. Hydrogen gas alleviates oxygen toxicity by reducing hydroxyl radical levels in PC12 cells.

    Directory of Open Access Journals (Sweden)

    Junchao Yu

    Full Text Available Hyperbaric oxygen (HBO therapy through breathing oxygen at the pressure of above 1 atmosphere absolute (ATA is useful for varieties of clinical conditions, especially hypoxic-ischemic diseases. Because of generation of reactive oxygen species (ROS, breathing oxygen gas at high pressures can cause oxygen toxicity in the central nervous system, leading to multiple neurological dysfunction, which limits the use of HBO therapy. Studies have shown that Hydrogen gas (H2 can diminish oxidative stress and effectively reduce active ROS associated with diseases. However, the effect of H2 on ROS generated from HBO therapy remains unclear. In this study, we investigated the effect of H2 on ROS during HBO therapy using PC12 cells. PC12 cells cultured in medium were exposed to oxygen gas or mixed oxygen gas and H2 at 1 ATA or 5 ATA. Cells viability and oxidation products and ROS were determined. The data showed that H2 promoted the cell viability and inhibited the damage in the cell and mitochondria membrane, reduced the levels of lipid peroxidation and DNA oxidation, and selectively decreased the levels of •OH but not disturbing the levels of O2•-, H2O2, or NO• in PC12 cells during HBO therapy. These results indicated that H2 effectively reduced •OH, protected cells against oxygen toxicity resulting from HBO therapy, and had no effect on other ROS. Our data supported that H2 could be potentially used as an antioxidant during HBO therapy.

  6. Preparation of Gas Sensor Based on Polymer Nanocomposite for Qualitative Detection of Hydrogen Sulfide

    Directory of Open Access Journals (Sweden)

    Elaheh Ghazizadeh

    2016-11-01

    Full Text Available Hydrogen sulfide (H2S, a by-product often produced in petrochemical processes, is well known as a dangerous and highly toxic gas to living organisms. The smell of H2S concentration of higher than 100 ppm can cause severe biological condition. Therefore, the detection of this gas is a crucial issue. In this work, nanocomposite porous films of polyurethane/silver (PU/Ag and poly(vinylchloride/silver (PVC/Ag consisting of 7 wt% nanoparticles were fabricated by phase inversion method and studied its qualitative detection capacity for H2S. The results indicated that after exposure to 50 ppm H2S, black points appeared on the surface of the test films within 10 min. However, the color completely disappeared when the films were left in the air for 20 min. Structural characteristics of the nanocomposites were studied by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, X-ray diffractometry (XRD and thermal gravimetric analysis (TGA to confirm possible interactions which may have formed between the polymers and nanoparticles. According to the results, Ag nanoparticles were well dispersed in PU and PVC matrices giving particle sizes of less than 62 and 76 nm, respectively. The observations revealed that two recommended nanocomposites (PU/Ag and PVC/Ag could be used for detection of hydrogen sulfide at low level concentration. The response of Ag-embedded polymer films toward H2S vapour showed a better detection by PU/Ag compared to PVC/Ag. Therefore, the suggested silver nanoparticle-loaded PU and PVC sensor films are easily portable, simple to use and cost-less compared with other types of hydrogen sulfide sensors.

  7. Enhancement of organic matter degradation and methane gas production of anaerobic granular sludge by degasification of dissolved hydrogen gas.

    Science.gov (United States)

    Satoh, Hisashi; Bandara, Wasala M K R T W; Sasakawa, Manabu; Nakahara, Yoshihito; Takahashi, Masahiro; Okabe, Satoshi

    2017-11-01

    A hollow fiber degassing membrane (DM) was applied to enhance organic matter degradation and methane gas production of anaerobic granular sludge process by reducing the dissolved hydrogen gas (D-H 2 ) concentration in the liquid phase. DM was installed in the bench-scale anaerobic granular sludge reactors and D-H 2 was removed through DM using a vacuum pump. Degasification improved the organic matter degradation efficiency to 79% while the efficiency was 62% without degasification at 12,000mgL -1 of the influent T-COD concentration. Measurement of D-H 2 concentrations in the liquid phase confirmed that D-H 2 was removed by degasification. Furthermore, the effect of acetate concentrations on the organic matter degradation efficiency was investigated. At acetate concentrations above 3gL -1 , organic matter degradation deteriorated. Degasification enhanced the propionate and acetate degradation. These results suggest that degasification reduced D-H 2 concentration and volatile fatty acids concentrations, prevented pH drop, and subsequent enhanced organic matter degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Deposition and modification of tantalum carbide coatings on graphite by laser interactions

    International Nuclear Information System (INIS)

    Veligdan, J.; Branch, D.; Vanier, P.E.; Barletta, R.E.

    1992-01-01

    Graphite surfaces can be hardened and protected from erosion by hydrogen at high temperatures by refractory metal carbide coatings, which are usually prepared by chemical vapor deposition (CVD) or chemical vapor reaction (CVR) methods. These techniques rely on heating the substrate to a temperature where a volatile metal halide decomposes and reacts with either a hydrocarbon gas or with carbon from the substrate. For CVR techniques, deposition temperatures must be in excess of 2000 degrees C in order to achieve favorable deposition kinetics. In an effort to lower the bulk substrate deposition temperature, the use of laser interactions with both the substrate and the metal halide deposition gas has been employed. Initial testing, involved the use of a CO 2 laser to heat the surface of a graphite substrate and a KrF excimer laser to accomplish a photodecomposition of TaCl 5 gas near the substrate. Results of preliminary experiments using these techniques are described

  9. Pressure of a partially ionized hydrogen gas: numerical results from exact low temperature expansions

    Energy Technology Data Exchange (ETDEWEB)

    Alastuey, A. [Laboratoire de Physique, ENS Lyon, CNRS, Lyon (France); Ballenegger, V. [Institut UTINAM, Universite de Franche-Comte, CNRS, Besancon (France)

    2010-01-15

    We consider a partially ionized hydrogen gas at low densities, where it reduces almost to an ideal mixture made with hydrogen atoms in their ground-state, ionized protons and ionized electrons. By performing systematic low-temperature expansions within the physical picture, in which the system is described as a quantum electron-proton plasma interacting via the Coulomb potential, exact formulae for the first.ve leading corrections to the ideal Saha equation of state have been derived[A. Alastuey, V. Ballenegger et al., J. Stat. Phys. 130, 1119 (2008)]. Those corrections account for all effects of interactions and thermal excitations up to order exp(E{sub H} /kT) included, where E{sub H} {approx_equal} -13.6 eV is the ground state energy of the hydrogen atom. Among the.ve leading corrections, three are easy to evaluate, while the remaining ones involve suitably truncated internal partition functions of H{sub 2} molecules and H{sup -} and H{sub 2}{sup +} ions, for which no analytical formulae are available in closed form. We estimate those partitions functions at.nite temperature via a simple phenomenology based on known values of rotational and vibrational energies. This allows us to compute numerically the leading deviations to the Saha pressure along several isotherms and isochores. Our values are compared with those of the OPAL tables (for pure hydrogen) calculated within the ACTEX method (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Application of Hydrogen Assisted Lean Operation to Natural Gas-Fueled Reciprocating Engines (HALO)

    Energy Technology Data Exchange (ETDEWEB)

    Chad Smutzer

    2006-01-01

    Two key challenges facing Natural Gas Engines used for cogeneration purposes are spark plug life and high NOx emissions. Using Hydrogen Assisted Lean Operation (HALO), these two keys issues are simultaneously addressed. HALO operation, as demonstrated in this project, allows stable engine operation to be achieved at ultra-lean (relative air/fuel ratios of 2) conditions, which virtually eliminates NOx production. NOx values of 10 ppm (0.07 g/bhp-hr NO) for 8% (LHV H2/LHV CH4) supplementation at an exhaust O2 level of 10% were demonstrated, which is a 98% NOx emissions reduction compared to the leanest unsupplemented operating condition. Spark ignition energy reduction (which will increase ignition system life) was carried out at an oxygen level of 9%, leading to a NOx emission level of 28 ppm (0.13 g/bhp-hr NO). The spark ignition energy reduction testing found that spark energy could be reduced 22% (from 151 mJ supplied to the coil) with 13% (LHV H2/LHV CH4) hydrogen supplementation, and even further reduced 27% with 17% hydrogen supplementation, with no reportable effect on NOx emissions for these conditions and with stable engine torque output. Another important result is that the combustion duration was shown to be only a function of hydrogen supplementation, not a function of ignition energy (until the ignitability limit was reached). The next logical step leading from these promising results is to see how much the spark energy reduction translates into increase in spark plug life, which may be accomplished by durability testing.

  11. Thermodynamic analyses of hydrogen production from sub-quality natural gas. Part I: Pyrolysis and autothermal pyrolysis

    Science.gov (United States)

    Huang, Cunping; T-Raissi, Ali

    Sub-quality natural gas (SQNG) is defined as natural gas whose composition exceeds pipeline specifications of nitrogen, carbon dioxide (CO 2) and/or hydrogen sulfide (H 2S). Approximately one-third of the U.S. natural gas resource is sub-quality gas [1]. Due to the high cost of removing H 2S from hydrocarbons using current processing technologies, SQNG wells are often capped and the gas remains in the ground. We propose and analyze a two-step hydrogen production scheme using SQNG as feedstock. The first step of the process involves hydrocarbon processing (via steam-methane reformation, autothermal steam-methane reformation, pyrolysis and autothermal pyrolysis) in the presence of H 2S. Our analyses reveal that H 2S existing in SQNG is stable and can be considered as an inert gas. No sulfur dioxide (SO 2) and/or sulfur trioxide (SO 3) is formed from the introduction of oxygen to SQNG. In the second step, after the separation of hydrogen from the main stream, un-reacted H 2S is used to reform the remaining methane, generating more hydrogen and carbon disulfide (CS 2). Thermodynamic analyses on SQNG feedstock containing up to 10% (v/v) H 2S have shown that no H 2S separation is required in this process. The Part I of this paper includes only thermodynamic analyses for SQNG pyrolysis and autothermal pyrolysis.

  12. The effect of a micro bubble dispersed gas phase on hydrogen isotope transport in liquid metals under nuclear irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fradera, J., E-mail: jfradera@ubu.es; Cuesta-López, S., E-mail: scuesta@ubu.es

    2013-12-15

    The present work intend to be a first step towards the understanding and quantification of the hydrogen isotope complex phenomena in liquid metals for nuclear technology. Liquid metals under nuclear irradiation in, e.g., breeding blankets of a nuclear fusion reactor would generate tritium which is to be extracted and recirculated as fuel. At the same time that tritium is bred, helium is also generated and may precipitate in the form of nano bubbles. Other liquid metal systems of a nuclear reactor involve hydrogen isotope absorption processes, e.g., tritium extraction system. Hence, hydrogen isotope absorption into gas bubbles modelling and control may have a capital importance regarding design, operation and safety. Here general models for hydrogen isotopes transport in liquid metal and absorption into gas phase, that do not depend on the mass transfer limiting regime, are exposed and implemented in OpenFOAM® CFD tool for 0D–3D simulations. Results for a 0D case show the impact of a He dispersed phase of nano bubbles on hydrogen isotopes inventory at different temperatures as well as the inventory evolution during a He nucleation event. In addition, 1D and 2D axisymmetric cases are exposed showing the effect of a He dispersed gas phase on hydrogen isotope permeation through a lithium lead eutectic alloy and the effect of vortical structures on hydrogen isotope transport at a backward facing step. Exposed results give a valuable insight on current nuclear technology regarding the importance of controlling hydrogen isotope transport and its interactions with nucleation event through gas absorption processes.

  13. Upgrading of reformate gas for different applications with focus on small-scale hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Jannasch, Anna-Karin; Silversand, Fredrik [CATATOR AB, Lund (Sweden)

    2004-12-01

    Hydrogen gas or hydrogen rich gas is today used in many different applications, i.e. as fuel in fuel cells or additive in vehicle fuel (i.e. hythane) and as reagent or reducing agent in different industrial product lines. The majority of the hydrogen is produced either via electrolysis or reformation, where this work has entirely been focused on the latter alternative. The overarching aims of this project have been to demonstrate the need for reformate purification for different applications, and then, to investigate different available methods that can be used in order to enable the requested gas clean-up. The different purification methods have been examined with respect to parameters such as operating conditions (temperature, pressure), impurity tolerance, size, weight and cost. Another goal of the project has been to investigate how the reformer fuel type used influences the reformate gas quality and hence, the need for gas purification before the reformate can be fed to e.g. a low temperature polymer membrane fuel cell (PEMFC). For this reason, some experimental work has been performed. First, analysis of the reformate gas composition when natural gas, LPG, gasoline, diesel, kerosene (low and high S-concentration (i.e. JP8)) and ethanol have been processed. The reformation tests were carried out in a small scale reformer unit ({approx} 1 kW H{sub 2}) including Catator's catalyst formulations developed for the steam reforming, the water gas shift and the preferential oxidation reaction, respectively. Verification tests, with synthetic gas blends, including different potential reformate impurities, and with real reformate gas were thereafter performed with a commercial 4-cell PEMFC stack (3-5 W). Finally, some examination and also to some extent further development of Catator's existing gas purification units were made, i.e. chemical (WGS, PROX) and physical (regenerative adsorption). The Pd-alloy membrane seems to be the obvious choice of purification

  14. Photovoltaic and Hydrogen Plant Integrated with a Gas Heat Pump for Greenhouse Heating: A Mathematical Study

    Directory of Open Access Journals (Sweden)

    Alexandros Sotirios Anifantis

    2018-02-01

    Full Text Available Nowadays, the traditional energy sources used for greenhouse heating are fossil fuels such as LPG, diesel and natural gas. The global energy demand will continue to grow and alternative technologies need to be developed in order to improve the sustainability of crop production in protected environments. Innovative solutions are represented by renewable energy plants such as photovoltaic, wind and geothermal integrated systems, however, these technologies need to be connected to the power grid in order to store the energy produced. On agricultural land, power grids are not widespread and stand-alone renewable energy systems should be investigated especially for greenhouse applications. The aim of this research is to analyze, by means of a mathematical model, the energy efficiency of a photovoltaic (8.2 kW, hydrogen (2.5 kW and ground source gas heat pump (2.2 kW integrated in a stand-alone system used for heating an experimental greenhouse tunnel (48 m2 during the winter season. A yearlong energy performance analysis was conducted for three different types of greenhouse cover materials, a single layer polyethylene film, an air inflated-double layer polyethylene film, and a double acrylic or polycarbonate. The results of one year showed that the integrated system had a total energy efficiency of 14.6%. Starting from the electric energy supplied by the photovoltaic array, the total efficiency of the hydrogen and ground source gas heat pump system was 112% if the coefficient of the performance of the heat pump is equal to 5. The heating system increased the greenhouse air temperatures by 3–9 °C with respect to the external air temperatures, depending on the greenhouse cover material used.

  15. A comprehensive review of microbial electrolysis cells (MEC reactor designs and configurations for sustainable hydrogen gas production

    Directory of Open Access Journals (Sweden)

    Abudukeremu Kadier

    2016-03-01

    Full Text Available Hydrogen gas has tremendous potential as an environmentally acceptable energy carrier for vehicles. A cutting edge technology called a microbial electrolysis cell (MEC can achieve sustainable and clean hydrogen production from a wide range of renewable biomass and wastewaters. Enhancing the hydrogen production rate and lowering the energy input are the main challenges of MEC technology. MEC reactor design is one of the crucial factors which directly influence on hydrogen and current production rate in MECs. The rector design is also a key factor to up-scaling. Traditional MEC designs incorporated membranes, but it was recently shown that membrane-free designs can lead to both high hydrogen recoveries and production rates. Since then multiple studies have developed reactors that operate without membranes. This review provides a brief overview of recent advances in research on scalable MEC reactor design and configurations.

  16. Impacts of seasonality on hydrogen production using natural gas pressure letdown stations. Paper no. IGEC-1-083

    International Nuclear Information System (INIS)

    Maddaloni, J.; Rowe, A.; Bailey, R.; McDonald, D.

    2005-01-01

    One of the difficulties associated with the development of a hydrogen economy is the creation of a supply infrastructure. A means for distributed hydrogen generation through a process using the exergy in high pressure natural gas streams has been proposed. The system recovers energy via expansion of natural gas through a turbo-expander at existing pressure reduction systems. Generated electric power is then used to drive an electrolyzer and create hydrogen. A model of the process is used to determine production rates for electricity and hydrogen given flow data for a number of pressure letdown sites in BC. Like many traditional renewable energy sources, most letdown stations have strong annual variations in flow conditions. Annual variations in stream flow rate, inlet pressure and inlet temperature can greatly affect hydrogen production rates. In the model, component efficiencies are scaled for operation at part-load, or away from optimum design conditions. Results indicate a significant reduction in predicted hydrogen production rates as compared to installed component name-plate capacity. Operating the system with a 'grid-tie' can increase the capacity factor, but economic viability will depend on local electricity and natural gas prices. (author)

  17. Thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

    2011-01-01

    A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

  18. Flow design and simulation of a gas compression system for hydrogen fusion energy production

    Energy Technology Data Exchange (ETDEWEB)

    Avital, E J; Salvatore, E [School of Engineering and Materials Science, Queen Mary University of London, Mile End Rd London E1 4NS (United Kingdom); Munjiza, A [Civil Engineering, University of Split, Livanjska 2100 Split (Croatia); Suponitsky, V; Plant, D; Laberge, M, E-mail: e.avital@qmul.ac.uk [General Fusion Inc.,108-3680 Bonneville Place, Burnaby, BC V3N 4T5 (Canada)

    2017-08-15

    An innovative gas compression system is proposed and computationally researched to achieve a short time response as needed in engineering applications such as hydrogen fusion energy reactors and high speed hammers. The system consists of a reservoir containing high pressure gas connected to a straight tube which in turn is connected to a spherical duct, where at the sphere’s centre plasma resides in the case of a fusion reactor. Diaphragm located inside the straight tube separates the reservoir’s high pressure gas from the rest of the plenum. Once the diaphragm is breached the high pressure gas enters the plenum to drive pistons located on the inner wall of the spherical duct that will eventually end compressing the plasma. Quasi-1D and axisymmetric flow formulations are used to design and analyse the flow dynamics. A spike is designed for the interface between the straight tube and the spherical duct to provide a smooth geometry transition for the flow. Flow simulations show high supersonic flow hitting the end of the spherical duct, generating a return shock wave propagating upstream and raising the pressure above the reservoir pressure as in the hammer wave problem, potentially giving temporary pressure boost to the pistons. Good agreement is revealed between the two flow formulations pointing to the usefulness of the quasi-1D formulation as a rapid solver. Nevertheless, a mild time delay in the axisymmetric flow simulation occurred due to moderate two-dimensionality effects. The compression system is settled down in a few milliseconds for a spherical duct of 0.8 m diameter using Helium gas and a uniform duct cross-section area. Various system geometries are analysed using instantaneous and time history flow plots. (paper)

  19. Flow design and simulation of a gas compression system for hydrogen fusion energy production

    Science.gov (United States)

    Avital, E. J.; Salvatore, E.; Munjiza, A.; Suponitsky, V.; Plant, D.; Laberge, M.

    2017-08-01

    An innovative gas compression system is proposed and computationally researched to achieve a short time response as needed in engineering applications such as hydrogen fusion energy reactors and high speed hammers. The system consists of a reservoir containing high pressure gas connected to a straight tube which in turn is connected to a spherical duct, where at the sphere’s centre plasma resides in the case of a fusion reactor. Diaphragm located inside the straight tube separates the reservoir’s high pressure gas from the rest of the plenum. Once the diaphragm is breached the high pressure gas enters the plenum to drive pistons located on the inner wall of the spherical duct that will eventually end compressing the plasma. Quasi-1D and axisymmetric flow formulations are used to design and analyse the flow dynamics. A spike is designed for the interface between the straight tube and the spherical duct to provide a smooth geometry transition for the flow. Flow simulations show high supersonic flow hitting the end of the spherical duct, generating a return shock wave propagating upstream and raising the pressure above the reservoir pressure as in the hammer wave problem, potentially giving temporary pressure boost to the pistons. Good agreement is revealed between the two flow formulations pointing to the usefulness of the quasi-1D formulation as a rapid solver. Nevertheless, a mild time delay in the axisymmetric flow simulation occurred due to moderate two-dimensionality effects. The compression system is settled down in a few milliseconds for a spherical duct of 0.8 m diameter using Helium gas and a uniform duct cross-section area. Various system geometries are analysed using instantaneous and time history flow plots.

  20. Principle design and data of graphite components

    International Nuclear Information System (INIS)

    Ishihara, Masahiro; Sumita, Junya; Shibata, Taiju; Iyoku, Tatsuo; Oku, Tatsuo

    2004-01-01

    The High Temperature Engineering Test Reactor (HTTR) constructed by Japan Atomic Energy Research Institute (JAERI) is a graphite-moderated and helium-gas-cooled reactor with prismatic fuel elements of hexagonal blocks. The reactor internal structures of the HTTR are mainly made up of graphite components. As well known, the graphite is a brittle material and there were no available design criteria for brittle materials. Therefore, JAERI had to develop the design criteria taking account of the brittle fracture behavior. In this paper, concept and key specification of the developed graphite design criteria is described, and also an outline of the quality control specified in the design criteria is mentioned

  1. System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2: Impact of gas heat recuperation and separation temperatures

    KAUST Repository

    Ehrhart, Brian D.; Muhich, Christopher L.; Al-Shankiti, Ibraheam; Weimer, Alan W.

    2016-01-01

    . The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas

  2. Techno-economic evaluation of hybrid systems for hydrogen production from biomass and natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, N. [Royal Institute of Technology, Stockholm (Sweden). Dept. of Energy Processes

    2001-07-01

    Hydrogen (H{sub 2}) is an alternative energy carrier, which is expected to significantly contribute to globally sustainable energy systems. It is environmentally friendly with high-energy density that makes it an excellent integrating fuel in transportation and power generation systems. This paper presents an assessment of the techno-economic viability of H{sub 2} production technologies based on hybrid systems using gasified biomass and natural gas combined with high temperature electrochemical shift. Assessment of the well-established thermal processes, high-temperature steam electrolysis (HTEL), and the plasma catalytic reforming (PCR) of light hydrocarbons developed at MIT are included for comparison. The results show that the PCR and HTEL processes are as cost-effective as the thermal steam reforming for H{sub 2} production when deployed on a commercial scale. The natural gas steam reforming (NGSR) is still the most favorable choice in energy and financial terms, while gasified biomass (GB) provides the highest production costs due to the intensive capital cost investments. The cost of H{sub 2} storage in the form of compressed gas or liquefied H{sub 2} also contributes significantly to total cost per kg produced H{sub 2}. 9 refs., 7 figs., 2 tabs.

  3. Performance and emission characteristics of a turbocharged CNG engine fueled by hydrogen-enriched compressed natural gas with high hydrogen ratio

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Fanhua; Wang, Mingyue; Jiang, Long; Chen, Renzhe; Deng, Jiao; Naeve, Nashay; Zhao, Shuli [State Key Laboratory of Automotive Safety and Energy Tsinghua University, Beijing 100084 (China)

    2010-06-15

    This paper investigates the effect of high hydrogen volumetric ratio of 55% on performance and emission characteristics in a turbocharged lean burn natural gas engine. The experimental data was conducted under various operating conditions including different spark timing, excess air ratio (lambda), and manifold pressure. It is found that the addition of hydrogen at a high volumetric ratio could significantly extend the lean burn limit, improve the engine lean burn ability, decrease burn duration, and yield higher thermal efficiency. The CO, CH{sub 4} emissions were reduced and NO{sub x} emission could be kept an acceptable low level with high hydrogen content under lean burn conditions when ignition timing were optimized. (author)

  4. Effects of ultraviolet and electron radiations on graphite-reinforced polysulfone and epoxy resins

    International Nuclear Information System (INIS)

    Giori, C.; Yamauchi, T.

    1984-01-01

    Degradation mechanisms have been investigated for graphite/polysulfone and graphite/epoxy laminates exposed to ultraviolet and high-energy electron radiations in vacuum up to 960 equivalent sun hours and 10 9 rads, respectively. Based on GC and combined GC/MS analysis of volatile by-products evolved during irradiation, several free radical mechanisms of composite degradation have been identified. All the composite materials evaluated have shown high electron radiation stability and relatively low ultraviolet stability as indicated by low G values and high quantum yields for gas formation. Mechanical property measurements of irradiated samples did not reveal significant changes, with the possible exception of UV exposed polysulfone laminates. Hydrogen and methane have been identified as the main byproducts of irradiation, along with unexpectedly high levels of CO and CO 2 . Initial G values for methane relative to hydrogen formation are higher in the presence of isopropylidene linkages, which occur in bisphenol-A resins

  5. Reduction of greenhouse gas emission on a medium-pressure boiler using hydrogen-rich fuel control

    International Nuclear Information System (INIS)

    Hsieh, S.-C.; Jou, Chih-Ju G.

    2007-01-01

    The increasing emission of greenhouse gases from the combustion of fossil fuel is believed to be responsible for global warming. A study was carried out to probe the influence of replacing fuel gas with hydrogen-rich refinery gas (R.G.) on the reduction of gas emission (CO 2 and NO x ) and energy saving. Test results show that the emission of CO 2 can be reduced by 16.4% annually (or 21,500 tons per year). The NO x emission can be 8.2% lower, or 75 tons less per year. Furthermore, the use of refinery gas leads to a saving of NT$57 million (approximately US$1.73 million) on fuel costs each year. There are no CO 2 , CO, SO x , unburned hydrocarbon, or particles generated from the combustion of added hydrogen. The hydrogen content in R.G. employed in this study was between 50 and 80 mol%, so the C/H ratio of the feeding fuel was reduced. Therefore, the use of hydrogen-rich fuel has practical benefits for both energy saving and the reduction of greenhouse gas emission

  6. The Role of Post Flame Oxidation on the UHC Emission for Combustion of Natural Gas and Hydrogen Containing fuels

    DEFF Research Database (Denmark)

    Jensen, Torben Kvist; Schramm, Jesper

    2003-01-01

    In-cylinder post flame oxidation of unburned hydro-carbons from crevices in a lean burn spark ignition engine has been examined for natural gas and mixtures of natural gas and a hydrogen containing producer gas. For this purpose a model was developed to describe the mixing of cold unburned...... during in-cylinder post oxidation. The Arrhenius parameters were determined using the reaction mechanism, which gave the prediction of the results from the combustion reactor experiments. The investigation showed that addition of producer gas to natural gas promotes the in-cylinder post oxidation...... significantly. Furthermore it was found that the cyclic variation in the post oxidation is reduced by addition of producer gas to natural gas....

  7. A dynamic model of a 100 kW micro gas turbine fuelled with natural gas and hydrogen blends and its application in a hybrid energy grid

    International Nuclear Information System (INIS)

    Di Gaeta, Alessandro; Reale, Fabrizio; Chiariello, Fabio; Massoli, Patrizio

    2017-01-01

    The paper deals with the development of a dynamic model of a commercial 100 kW Micro Gas Turbine (MGT) fuelled with mixtures of standard (i.e. natural gas or methane) and alternative fuels (i.e. hydrogen). The model consists of a first-order differential equation (ODE) describing the dominant dynamics of the MGT imposed by its own control system during production electrical power. The differential equation is coupled to a set of nonlinear maps derived numerically from a detailed 0D thermodynamic matching model of the MGT evaluated over a wide range of operating conditions (i.e. mechanical power, fraction of hydrogen and ambient temperature). The efficiency of the electrical machine with power inverter and power absorbed by auxiliary devices is also taken into account. The resulting model is experimentally validated for a sequence of power step responses of the MGT at different ambient conditions and with different fuel mixtures. The model is suited for simulation and control of hybrid energy grids (HEGs) which rely on advanced use of MGT and hydrogen as energy carrier. In this regard, the MGT model is used in the simulation of an HEG based on an appropriate mix of renewable (non-programmable) and non-renewable (programmable) energy sources with hydrogen storage and its reuse in the MGT. Here, the MGT is used as a programmable energy vector for compensating the deficits of renewable energies (such as solar and wind) with respect to user demand, while excess renewable energy is used to produce hydrogen via electrolysis of water. The simulated HEG comprises a solar PhotoVoltaic (PV) plant (300 kW), an MGT (100 kW) fuelled with natural gas and hydrogen blends, a water electrolyzer (WE) system (8 bar, 56 Nm 3 /h), a hydrogen tank (54 m 3 ), and an Energy Management Control System (EMCS). - Highlights: • A dynamic model of a commercial 100 kW MGT fuelled with natural gas and hydrogen blends is developed. • The model reproduces the electrical power generated by

  8. Nuclear graphite for high temperature reactors

    International Nuclear Information System (INIS)

    Marsden, B.J.

    2001-01-01

    The cores and reflectors in modern High Temperature Gas Cooled Reactors (HTRs) are constructed from graphite components. There are two main designs; the Pebble Bed design and the Prism design. In both of these designs the graphite not only acts as a moderator, but is also a major structural component that may provide channels for the fuel and coolant gas, channels for control and safety shut off devices and provide thermal and neutron shielding. In addition, graphite components may act as a heat sink or conduction path during reactor trips and transients. During reactor operation, many of the graphite component physical properties are significantly changed by irradiation. These changes lead to the generation of significant internal shrinkage stresses and thermal shut down stresses that could lead to component failure. In addition, if the graphite is irradiated to a very high irradiation dose, irradiation swelling can lead to a rapid reduction in modulus and strength, making the component friable.The irradiation behaviour of graphite is strongly dependent on its virgin microstructure, which is determined by the manufacturing route. Nevertheless, there are available, irradiation data on many obsolete graphites of known microstructures. There is also a well-developed physical understanding of the process of irradiation damage in graphite. This paper proposes a specification for graphite suitable for modern HTRs. (author)

  9. Gas explosions and thermal runaways during external heating abuse of commercial lithium-ion graphite-LiCoO2 cells at different levels of ageing

    Science.gov (United States)

    Larsson, Fredrik; Bertilsson, Simon; Furlani, Maurizio; Albinsson, Ingvar; Mellander, Bengt-Erik

    2018-01-01

    Commercial 6.8 Ah lithium-ion cells with different ageing/status have been