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Sample records for simulated supercritical water

  1. Simulations of dissociation constants in low pressure supercritical water

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  2. Solvation in supercritical water

    SciTech Connect

    Cochran, H.D. ); Cummings, P.T.; Karaborni, S. . Dept. of Chemical Engineering)

    1991-01-01

    The aim of this work is to determine the solvation structure in supercritical water composed with that in ambient water and in simple supercritical solvents. Molecular dynamics studies have been undertaken of systems that model ionic sodium and chloride, atomic argon, and molecular methanol in supercritical aqueous solutions using the simple point charge model of Berendsen for water. Because of the strong interactions between water and ions, ionic solutes are strongly attractive in supercritical water, forming large clusters of water molecules around each ion. Methanol is found to be a weakly-attractive solute in supercritical water. The cluster of excess water molecules surrounding a dissolved ion or polar molecule in supercritical aqueous solutions is comparable to the solvent clusters surrounding attractive solutes in simple supercritical fluids. Likewise, the deficit of water molecules surrounding a dissolved argon atom in supercritical aqueous solutions is comparable to that surrounding repulsive solutes in simple supercritical fluids. The number of hydrogen bonds per water molecule in supercritical water was found to be about one third the number in ambient water. The number of hydrogen bonds per water molecule surrounding a central particle in supercritical water was only mildly affected by the identify of the central particle--atom, molecule, or ion. These results should be helpful in developing a qualitative understanding of important processes that occur in supercritical water. 29 refs., 6 figs.

  3. Microstructure of ambient and supercritical water. Direct comparison between simulation and neutron scattering experiments

    SciTech Connect

    Chialvo, A.A.; Cummings, P.T. |

    1996-01-25

    Molecular dynamics simulations of SPC, SPC/E, TIP4P, and ST2 water models are performed at ambient and two supercritical conditions make a direct comparison with recent microstructural data obtained by neutron diffraction with isotopic substitution (NDIS) experiments. The models generally fail to accurately predict details of the NDIS results at supercritical conditions, even though they are somewhat successful at ambient conditions. The failure is not as pronounced as that expected by Postorino et al. because of an unusual density dependence in the structure predicted by two of the models. We also evaluate a model for supercritical water denoted SPCG, a modification of the SPC and SPC/E models, in which the dipole moment is reduced to the bare dipole moment of water. For this model, the predicted structure at supercritical conditions is in much better agreement with experiment. A geometric definition of hydrogen bonding is used to gain insight into the angular dependence of the H...O pair distribution function g{sub OH}(r,{omega}). The simulation results for the five models indicate a strong orientational dependence for the g{sub OH}(r,{omega}) along the H-bonding orientations, with an approximately constant relative strength from ambient to supercritical conditions, suggesting that the angle-averaged radial distribution function, g{sub OH}(r), and its volume integral over the first solvation shell, n{sub OH}(r), may not in themselves be good measures of the strength of the H-bonding. 46 refs., 15 figs., 2 tabs.

  4. Survey: Destruction of chemical agent simulants in supercritical water oxidation. Master's thesis

    SciTech Connect

    Blank, M.R.

    1992-07-01

    The supercritical water oxidation (SCWO) process exhibits distinct advantages for destruction of toxic wastes. Examples of these wastes are two chemical agent simulants, dimethyl methylphosphonate (DMMP) and thiodiglycol (2,2'-thiodiethanol). DMMP is similar to the nerve agent GB Sarin in structure, and thiodiglycol is a hydrolysis product of the blister agent HD Sulfur Mustard. Both simulants are miscible in water and relatively non-toxic in comparison to the actual chemical agents. Using a Laboratory-scale, batch three temperatures were investigated: 425 deg C, 450 deg C, and 500 deg C with an initial concentration of one percent by volume, 11,450 mg/L for DMMP and 12,220 mg/L for thiodiglycol. Residence times investigated were: 1, 2, 3, 6, and 8 minutes. Reactor beat-up (H.U.) was determined to be one minute. Both pyrolysis and oxidation tests were conducted. Oxygen levels were uniformly set at 200% of stoichiometric requirements for the parent compounds.

  5. Assessment of hydrogen bonding effect on ionization of water from ambient to supercritical region-MD simulation approach

    NASA Astrophysics Data System (ADS)

    Swiatla-Wojcik, D.; Mozumder, A.

    2014-04-01

    We present a novel, molecular dynamics (MD) simulation based, strategy to analyze how the degree of hydrogen bonding may influence the ionization and dissociation of water upon heating from ambient to supercritical temperatures. Calculations show a negligible change in the ionization energy up to 200 °C. At higher temperatures the ionization energy increases due to the decreasing degree of hydrogen bonding. The influence of density (pressure) is pronounced in the supercritical region. The ionization is more energy consuming in the less dense fluid. We also show that high temperature and low density may promote dissociation of the electronically excited water molecules. Implications on the initial radiation chemical yields of the hydrated electron, hydrogen atom and hydroxyl radical are discussed.

  6. Correlated Particle Motion and THz Spectral Response of Supercritical Water

    NASA Astrophysics Data System (ADS)

    Śmiechowski, Maciej; Schran, Christoph; Forbert, Harald; Marx, Dominik

    2016-01-01

    Molecular dynamics simulations of supercritical water reveal distinctly different distance-dependent modulations of dipolar response and correlations in particle motion compared to ambient conditions. The strongly perturbed H-bond network of water at supercritical conditions allows for considerable translational and rotational freedom of individual molecules. These changes give rise to substantially different infrared spectra and vibrational density of states at THz frequencies for densities above and below the Widom line that separates percolating liquidlike and clustered gaslike supercritical water.

  7. Removing Solids From Supercritical Water

    NASA Technical Reports Server (NTRS)

    Hong, Glenn T.

    1992-01-01

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

  8. iTOUGH2-EOS1SC. Multiphase Reservoir Simulator for Water under Sub- and Supercritical Conditions. User's Guide

    SciTech Connect

    Magnusdottir, Lilja; Finsterle, Stefan

    2015-03-01

    Supercritical fluids exist near magmatic heat sources in geothermal reservoirs, and the high enthalpy fluid is becoming more desirable for energy production with advancing technology. In geothermal modeling, the roots of the geothermal systems are normally avoided but in order to accurately predict the thermal behavior when wells are drilled close to magmatic intrusions, it is necessary to incorporate the heat sources into the modeling scheme. Modeling supercritical conditions poses a variety of challenges due to the large gradients in fluid properties near the critical zone. This work focused on using the iTOUGH2 simulator to model the extreme temperature and pressure conditions in magmatic geothermal systems.

  9. Supercritical Water Mixture (SCWM) Experiment

    NASA Technical Reports Server (NTRS)

    Hicks, Michael C.; Hegde, Uday G.

    2012-01-01

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

  10. Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.

    PubMed

    Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

    2015-01-01

    CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena. PMID:25427299

  11. Supercritical Water Oxidation Data Acquisition Testing

    SciTech Connect

    K. M. Garcia

    1996-08-01

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

  12. Supercritical water oxidation - Microgravity solids separation

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Webley, Paul A.; Tester, Jefferson W.

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Olanrewaju, Kazeem Bode

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

  15. Successful treatment with supercritical water oxidation

    SciTech Connect

    Jensen, R.

    1994-06-01

    Supercritical Water Oxidation (SCWO) operates in a totally enclosed system. It uses water at high temperatures and high pressure to chemically change wastes. Oily substances become soluble and complex hydrocarbons are converted into water and carbon dioxide. Research and development on SCWO is described.

  16. The partial pair correlation functions of dense supercritical water

    NASA Astrophysics Data System (ADS)

    Tassaing, T.; Bellissent-Funel, M.-C.; Guillot, B.; Guissani, Y.

    1998-05-01

    Neutron diffraction measurements of heavy water and of two isotopic H2O/D2O mixtures at supercritical state (T = 380 °C and ρD2O = 0.73 g/cm3) are presented. In combining the set of neutron diffraction data with previous X-rays measurements of Yamanaka et al. (J. Chem. Phys., 101 (1994) 9830), it has been possible by using a Monte Carlo method to reach the partial pair correlation functions gOH(r), gHH(r) and gOO(r). The results are compared with molecular-dynamics simulations using the SPCE pair potential for water. These new results confirm that hydrogen bonding is still present in dense supercritical water.

  17. Supercritical water oxidation of landfill leachate

    SciTech Connect

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

    2011-09-15

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

  18. Supercritical water oxidation data acquisition testing. Final report, Volume II

    SciTech Connect

    1996-11-01

    Supercritical Water Oxidation (SCWO) technology holds great promise for treating mixed wastes, in an environmentally safe and efficient manner. In the spring of 1994 the US Department of Energy (DOE), Idaho Operations Office awarded Stone & Webster Engineering Corporation, of Boston Massachusetts and its sub-contractor MODAR, Inc. of Natick Massachusetts a Supercritical Water Oxidation Data Acquisition Testing (SCWODAT) program. The SCWODAT program was contracted through a Cooperative Agreement that was co-funded by the US Department of Energy and the Strategic Environmental Research and Development Program. The SCWODAT testing scope outlined by the DOE in the original Cooperative Agreement and amendments thereto was initiated in June 1994 and successfully completed in December 1995. The SCWODAT program provided further information and operational data on the effectiveness of treating both simulated mixed waste and typical Navy hazardous waste using the MODAR SCWO technology.

  19. Supercritical water oxidation of products of human metabolism

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  20. Supercritical methanol for polyethylene terephthalate depolymerization: observation using simulator.

    PubMed

    Genta, Minoru; Iwaya, Tomoko; Sasaki, Mitsuru; Goto, Motonobu

    2007-01-01

    To apply PET depolymerization in supercritical methanol to commercial recycling, the benefits of supercritical methanol usage in PET depolymerization was investigated from the viewpoint of the reaction rate and energy demands. PET was depolymerized in a batch reactor at 573 K in supercritical methanol under 14.7 MPa and in vapor methanol under 0.98 MPa in our previous work. The main products of both reactions were the PET monomers of dimethyl terephthalate (DMT) and ethylene glycol (EG). The rate of PET depolymerization in supercritical methanol was faster than that of PET depolymerization in vapor methanol. This indicates supercritical fluid is beneficial in reducing reaction time without the use of a catalyst. We depicted the simple process flow of PET depolymerization in supercritical methanol and in vapor methanol, and by simulation evaluated the total heat demand of each process. In this simulation, bis-hydroxyethyl terephthalate (BHET) was used as a model component of PET. The total heat demand of PET depolymerization in supercritical methanol was 2.35 x 10(6)kJ/kmol Produced-DMT. That of PET depolymerization in vapor methanol was 2.84 x 10(6)kJ/kmol Produced-DMT. The smaller total heat demand of PET depolymerization in supercritical methanol clearly reveals the advantage of using supercritical fluid in terms of energy savings. PMID:16914302

  1. Supercritical methanol for polyethylene terephthalate depolymerization: Observation using simulator

    SciTech Connect

    Genta, Minoru; Iwaya, Tomoko; Sasaki, Mitsuru; Goto, Motonobu

    2007-07-01

    To apply PET depolymerization in supercritical methanol to commercial recycling, the benefits of supercritical methanol usage in PET depolymerization was investigated from the viewpoint of the reaction rate and energy demands. PET was depolymerized in a batch reactor at 573 K in supercritical methanol under 14.7 MPa and in vapor methanol under 0.98 MPa in our previous work. The main products of both reactions were the PET monomers of dimethyl terephthalate (DMT) and ethylene glycol (EG). The rate of PET depolymerization in supercritical methanol was faster than that of PET depolymerization in vapor methanol. This indicates supercritical fluid is beneficial in reducing reaction time without the use of a catalyst. We depicted the simple process flow of PET depolymerization in supercritical methanol and in vapor methanol, and by simulation evaluated the total heat demand of each process. In this simulation, bis-hydroxyethyl terephthalate (BHET) was used as a model component of PET. The total heat demand of PET depolymerization in supercritical methanol was 2.35 x 10{sup 6} kJ/kmol Produced-DMT. That of PET depolymerization in vapor methanol was 2.84 x 10{sup 6} kJ/kmol Produced-DMT. The smaller total heat demand of PET depolymerization in supercritical methanol clearly reveals the advantage of using supercritical fluid in terms of energy savings.

  2. Supercritical water oxidation technology for DWPF

    SciTech Connect

    Carter, J.T.; Gentilucci, J.A.

    1992-02-07

    At the request of Mr. H.L. Brandt and others in the Savannah River Field Office High Level Waste Division office, DWPF, and SRL personnel have reviewed two potential applications for supercritical water oxidation technology in DWPF. The first application would replace the current hydrolysis process by destroying the organic fractions of the precipitated cesium / potassium tetraphenylborate slurry. The second application pertains to liquid benzene destruction. After a thorough evaluation the first application is not recommended. The second is ready to be tested if needed.

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

    NASA Astrophysics Data System (ADS)

    Goto, Motonobu

    2010-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Movassat, Mohammad; Bailey, Joanne; Yetisir, Metin

    2015-11-01

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

  5. Containment system for supercritical water oxidation reactor

    SciTech Connect

    Chastagner, P.

    1991-12-31

    This invention is comprised of a system for containment of a supercritical water oxidation reactor in the event of a rupture of the reactor. The system includes a containment for housing the reaction vessel and a communicating chamber for holding a volume of coolant, such as water. The coolant is recirculated and sprayed to entrain and cool any reactants that might have escaped from the reaction vessel. Baffles at the entrance to the chamber prevent the sprayed coolant from contacting the reaction vessel. An impact-absorbing layer is positioned between the vessel and the containment to at least partially absorb momentum of any fragments propelled by the rupturing vessel. Remote, quick-disconnecting fittings exterior to the containment, in cooperation with shut-off valves, enable the vessel to be isolated and the system safely taken off-line. Normally-closed orifices throughout the containment and chamber enable decontamination of interior surfaces when necessary.

  6. Containment system for supercritical water oxidation reactor

    DOEpatents

    Chastagner, Philippe

    1994-01-01

    A system for containment of a supercritical water oxidation reactor in the event of a rupture of the reactor. The system includes a containment for housing the reaction vessel and a communicating chamber for holding a volume of coolant, such as water. The coolant is recirculated and sprayed to entrain and cool any reactants that might have escaped from the reaction vessel. Baffles at the entrance to the chamber prevent the sprayed coolant from contacting the reaction vessel. An impact-absorbing layer is positioned between the vessel and the containment to at least partially absorb momentum of any fragments propelled by the rupturing vessel. Remote, quick-disconnecting fittings exterior to the containment, in cooperation with shut-off valves, enable the vessel to be isolated and the system safely taken off-line. Normally-closed orifices throughout the containment and chamber enable decontamination of interior surfaces when necessary.

  7. Containment system for supercritical water oxidation reactor

    DOEpatents

    Chastagner, P.

    1994-07-05

    A system is described for containment of a supercritical water oxidation reactor in the event of a rupture of the reactor. The system includes a containment for housing the reaction vessel and a communicating chamber for holding a volume of coolant, such as water. The coolant is recirculated and sprayed to entrain and cool any reactants that might have escaped from the reaction vessel. Baffles at the entrance to the chamber prevent the sprayed coolant from contacting the reaction vessel. An impact-absorbing layer is positioned between the vessel and the containment to at least partially absorb momentum of any fragments propelled by the rupturing vessel. Remote, quick-disconnecting fittings exterior to the containment, in cooperation with shut-off valves, enable the vessel to be isolated and the system safely taken off-line. Normally-closed orifices throughout the containment and chamber enable decontamination of interior surfaces when necessary. 2 figures.

  8. Pyrite in contact with supercritical water: the desolation of steam.

    PubMed

    Stirling, András; Rozgonyi, Tamás; Krack, Matthias; Bernasconi, Marco

    2015-07-14

    The supercritical water-pyrite interface has been studied by ab initio molecular dynamics simulation. Extreme conditions are relevant in the iron-sulfur world (ISW) theory where prebiotic chemical reactions are postulated to occur at the mineral-water interface. We have investigated the properties of this interface under such conditions. We have come to the conclusion that hot-pressurized water on pyrite leads to an interface where a dry pyrite surface is in contact with the nearby SC water without significant chemical interactions. This picture is markedly different from that under ambient conditions where the surface is fully covered with adsorbed water molecules which is of relevance for the surface reactions of the ISW hypothesis. PMID:26077541

  9. Gasification of cyanobacterial in supercritical water.

    PubMed

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

    2014-01-01

    Cyanobacterial collected from eutrophic freshwater lakes constituted intractable waste with a rich algae biomass content. Supercritical water gasification (SCWG) was proposed to treat the cyanobacterial and to produce hydrogen for energy. The H 2 yield reached 2.92 mol/kg at reaction conditions of 500 °C, 30 min and 22 MPa; this yield accounted for 26% of the total gaseous products. Abundant ammonia and dissolved reactive phosphorous were concentrated in the liquid product, which could be recovered and used as a liquid fertilizer. Solid residue, which accounted only for about 1% of the wet weight, was mainly composed of coke and ash. The efficiency of H 2 production was better than that from other biomass, because of the abundant organic matter in cyanobacterial. Thus, cyanobacterial are an ideal biomass feedstock for H 2 production from SCWG. PMID:25176482

  10. NMR study of compressed supercritical water

    NASA Astrophysics Data System (ADS)

    Lamb, W. J.; Jonas, J.

    1981-01-01

    The proton spin-lattice relaxation time T1 in water has been measured as a function of pressure in the temperature range 150 to 700°C. This study focuses on the supercritical region (tc=374°C) where the spin-rotation interaction mechanism dominates the observed proton relaxation rate. Since water is an asymmetric top molecule, the analysis of the experimental data involves a number of simplifying assumptions discussed in detail. The experimental finding that in supercritical water the spin-rotation relaxation time T 1SR is a linear function of density ρ, up to relatively high densities (ρ≃ 1.5 ρc) provides rationale for analysis of the NMR experimental data in terms of a model used for dilute gases. The T 1SR data are analyzed on the basis of the assumption that the collision modulated spin-rotation interactions can be described by a single correlation function which is an exponential function of time. Using this procedure, we find that T 1SR/ρ αT-2, i.e.T 1SR/ρ exhibits a stronger temperature dependence than that found (T 1SR/ρ αT-3/2) for many polar and nonpolar gases. The calculated effective cross sections for the transfer of angular momentum σeff which show strong temperature dependence (σeff αT-1.5) are several times larger than the kinetic cross sections. By assuming applicability of expressions derived for isotropic reorientation of spherical-top molecules and using the effective spin-rotation interaction constant as obtained from microwave measurements, we are able to calculate the angular momentum correlation time τJ, over the range of temperatures and densities studied. In the supercritical region τJ⩾τΘ, where τΘ is the reorientational correlation time, and the estimated mean angle of reorientation ΔΘ¯ is in the range 50° to 800°. The T 1SR data are also interpreted in terms of the modified rough hard sphere (RHS) model which for ρ<2ρc takes into account the effect of attractive forces. We find that 1/T 1SR is a linear

  11. Dynamical and structural properties of benzene in supercritical water.

    PubMed

    Nieto-Draghi, Carlos; Bonet Avalos, Josep; Contreras, Oliver; Ungerer, Philippe; Ridard, Jacqueline

    2004-12-01

    We have employed an anisotropic united atom model of benzene (R. O. Contreras, Ph.D. thesis, Universitat Rovira i Virgili 2002) that reproduces the quadrupolar moment of this molecule through the inclusion of seven point charges. We show that this kind of interaction is required to reproduce the solvation of these molecules in supercritical water. We have computed self-diffusion coefficient and Maxwell-Stefan coefficients as well as the shear viscosity for the mixture water-benzene at supercritical conditions. A strong density and composition dependence of these properties is observed. In addition, our simulations are in qualitative agreement with the experimental evidence that, at medium densities (0.6 g/cm(3) and 673 K), almost half of the benzene molecules have one hydrogen bond with water molecules. We also observe that these bonds are longer lived than the corresponding hydrogen bonds between water molecules. Similarly, we obtain an important reduction of the dielectric constant of the mixture with the increment of the amount of benzene molecules at medium and high densities. PMID:15549940

  12. Code System for Supercritical Water Cooled Reactor LOCA Analysis.

    Energy Science and Technology Software Center (ESTSC)

    1999-10-13

    Version 00 The new SCRELA code was developed to analyze the LOCA of the supercritical water cooled reactor. Since the currently available LWR codes for LOCA analysis could not analyze the significant differences in reactor characteristics between the supercritical-water cooled reactor and the current LWR, the first objective of this code development was to analyze the uniqueness of this reactor. The behavior of the supercritical water in the blowdown phase and the reflood phase ismore » modeled.« less

  13. Near Term Application of Supercritical Water Technologies

    SciTech Connect

    Vogt, Bastian; Starflinger, Joerg; Schulenberg, Thomas

    2006-07-01

    A pressurized water reactor with a supercritical water primary loop is analyzed (PWR-SC) within this paper. It will be shown that the PWR-SC offers considerable advantages in the fields of safety, economy and efficiency compared with a conventional PWR design. A cycle analysis shows that the net plant efficiency increases by 2% compared to currently operated or built systems. In addition, the mass flow rate of the primary side is strongly decreased, which enables a reduction of the primary pump power by a factor of 4. In the secondary loop, the mass flow rate can be decreased by about 15%, which allows down-scaling of all secondary side components such as turbines, condensers and feed-water preheat systems as a consequence of the high core exit temperature. A coupled core analysis and a hot channel factor analysis are performed to demonstrate the promising safety features of the PWR-SC and to show the technical feasibility of such a system. (authors)

  14. Corrosion Behavior of Candidate Alloys for Supercritical Water Reactors

    SciTech Connect

    Sridharan, K.; Zillmer, A.; Licht, J.R.; Allen, T.R.; Anderson, M.H.; Tan, L.

    2004-07-01

    The corrosion and stress corrosion cracking behavior of metallic cladding and other core internal structures is critical to the success of the Generation IV Supercritical Water-cooled Reactors (SCWR). The eventual materials selected will be chosen based on the combined corrosion, stress-corrosion, mechanical performance, and radiation stability properties. Among the materials being considered are austenitic stainless steels, ferritic/martensitic steels, and nickel-base alloys. This paper reports initial studies on the corrosion performance of the candidate alloys 316 austenitic stainless steel, Inconel 718, and Zircaloy-2, all exposed to supercritical water at 300-500 deg. C in a corrosion loop at the University of Wisconsin. Long-term corrosion performance of AISI 347, also a candidate austenitic steel, has also been examined by sectioning samples from a component that was exposed for a period of about 30 years in supercritical water at the Genoa 3 Supercritical Water fossil power plant located in Genoa, Wisconsin. (authors)

  15. Stability Analysis of a Uniformly Heated Channel with Supercritical Water

    SciTech Connect

    Ortega Gomez, T.; Class, A.; Schulenberg, T.; Lahey, R.T. Jr.

    2006-07-01

    The thermal-hydraulic stability of a uniformly heated channel at supercritical water pressure has been investigated to help understand the system instability phenomena which may occur in Supercritical Water Nuclear Reactors (SCWR). We have extended the modeling approach often used for Boiling Water Nuclear Reactor (BWR) stability analysis to supercritical pressure operation conditions. We have shown that Ledinegg excursive instabilities and pressure-drop oscillations (PDO) will not occur in supercritical water systems. The linear stability characteristics of a typical uniformly heated channel were computed by evaluating the eigenvalues of the model. An analysis of non-linear instability phenomena was also performed in the time domain and the dynamic bifurcations were evaluated. (authors)

  16. Process for treating effluent from a supercritical water oxidation reactor

    DOEpatents

    Barnes, Charles M.; Shapiro, Carolyn

    1997-01-01

    A method for treating a gaseous effluent from a supercritical water oxidation reactor containing entrained solids is provided comprising the steps of expanding the gas/solids effluent from a first to a second lower pressure at a temperature at which no liquid condenses; separating the solids from the gas effluent; neutralizing the effluent to remove any acid gases; condensing the effluent; and retaining the purified effluent to the supercritical water oxidation reactor.

  17. Process for treating effluent from a supercritical water oxidation reactor

    DOEpatents

    Barnes, C.M.; Shapiro, C.

    1997-11-25

    A method for treating a gaseous effluent from a supercritical water oxidation reactor containing entrained solids is provided comprising the steps of expanding the gas/solids effluent from a first to a second lower pressure at a temperature at which no liquid condenses; separating the solids from the gas effluent; neutralizing the effluent to remove any acid gases; condensing the effluent; and retaining the purified effluent to the supercritical water oxidation reactor. 6 figs.

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

    SciTech Connect

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

    2015-09-21

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

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

    PubMed

    Corradini, D; Rovere, M; Gallo, P

    2015-09-21

    In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones. PMID:26395714

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  1. Supercritical water oxidation benchscale testing metallurgical analysis report

    SciTech Connect

    Norby, B.C.

    1993-02-01

    This report describes metallurgical evaluation of witness wires from a series of tests using supercritical water oxidation (SCWO) to process cutting oil containing a simulated radionuclide. The goal of the tests was to evaluate the technology`s ability to process a highly chlorinated waste representative of many mixed waste streams generated in the DOE complex. The testing was conducted with a bench-scale SCWO system developed by the Modell Development Corporation. Significant test objectives included process optimization for adequate destruction efficiency, tracking the radionuclide simulant and certain metals in the effluent streams, and assessment of reactor material degradation resulting from processing a highly chlorinated waste. The metallurgical evaluation described herein includes results of metallographic analysis and Scanning Electron Microscopy analysis of witness wires exposed to the SCWO environment for one test series.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Technical Reports Server (NTRS)

    Hegde, Uday; Hicks, Michael

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  5. Multidimensional Model of Fluid Flow and Heat Transfer in Generation-IV Supercritical Water Reactors

    SciTech Connect

    Gallaway, Tara; Antal, Steven P.; Podowski, Michael Z.

    2006-07-01

    This paper is concerned with the mechanistic modeling and theoretical/computational analysis of flow and heat transfer in future Generation-IV Supercritical Water Cooled Reactors (SCWR). The issues discussed in the paper include: the development of analytical models of the properties of supercritical water, and the application of full three-dimensional computational modeling framework to simulate fluid flow and heat transfer in SCWRs. Several results of calculations are shown, including the evaluation of water properties (density, specific heat, thermal conductivity, viscosity, and Prandtl number) near the pseudo-critical temperature for various supercritical pressures, and the CFD predictions using the NPHASE computer code. It is demonstrated that the proposed approach is very promising for future mechanistic analyses of SCWR thermal-hydraulics and safety. (authors)

  6. Research of a Supercritical Pressure Water Cooled Reactor in Korea

    SciTech Connect

    Bae, Yoon-Yeong; Joo, Hyung-Kook; Jang, Jinsung; Jeong, Yong-Hwan; Song, Jin-ho; Yoon, Han-Young; Yoo, Jung-Yul

    2004-07-01

    In this paper the activities on the supercritical pressure water-cooled reactor (SCWR) in Korea are briefly introduced. Four projects on a SCWR are being conducted in Korea. Three of them are supported by the I-NERI program while one is by KAERI. Two of the I-NERI-supported projects concern suitable materials for supercritical pressure and temperature, and radiation environment. The other I-NERI-supported project surveys numerically and experimentally the proper turbulence modeling for the numerical calculation of heat transfer phenomena at a supercritical condition. Heat transfer at a supercritical condition is being studied at KAERI experimentally using carbon dioxide as a coolant. The test loop is to be completed by the end of 2004. (authors)

  7. Heat transfer research on supercritical water flow upward in tube

    SciTech Connect

    Li, H. B.; Yang, J.; Gu, H. Y.; Zhao, M.; Lu, D. H.; Zhang, J. M.; Wang, F.; Zhang, Y.

    2012-07-01

    The experimental research of heat transfer on supercritical water has been carried out on the supercritical water multipurpose test loop with a 7.6 mm upright tube. The experimental data of heat transfer is obtained. The experimental results of thermal-hydraulic parameters on flow and heat transfer of supercritical water show that: Heat transfer enhancement occurs when the fluid temperature reaches pseudo-critical point with low mass flow velocity, and peters out when the mass flow velocity increases. The heat transfer coefficient and Nusselt number decrease with the heat flux or system pressure increases, and increase with the increasing of mass flow velocity. The wall temperature increases when the mass flow velocity decreases or the system pressure increases. (authors)

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

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

    PubMed

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

    2015-01-01

    Influences of temperature and oxidation coefficient (n) on sewage sludge treatment in supercritical water and its corresponding reaction mechanism were studied. Moreover, the combined process of supercritical water gasification (SCWG) and supercritical water oxidation (SCWO) was also investigated. The results show that ammonia nitrogen, phenols and pyridines are main refractory intermediates. The weight of solid products at 873K and n=4 is only 3.5wt.% of the initial weight, which is lower than that after combustion. Volatile organics in solid phase have almost released at 723K and n=0. Highest yield of combustible gases was obtained at n=0, and H2 yield can reach 11.81mol/kg at 873K. Furthermore, the combination of SCWG at 723K and SCWO at 873K with a total n=1 is feasible for its good effluent quality and low operation costs. PMID:25461006

  10. Simulated propeller slipstream effects on a supercritical wing

    NASA Technical Reports Server (NTRS)

    Welge, H. R.; Crowder, J. P.

    1978-01-01

    To quantify the installed performance of high speed (M = 0.8) turboprop propulsion systems, an experimental program designed to assess the magnitude of the aerodynamic interference of a propeller slipstream on a supercritical wing has been conducted. The test was conducted in the NASA Ames 14-foot wind tunnel. An ejector-nacelle propeller slipstream simulator was used to produce a slipstream with characteristics typical of advanced propellers presently being investigated. A supercritical wing-body configuration was used to evaluate the interference effects. A traversing total pressure rake was used to make flow field measurements behind the wing and to calibrate the slipstream simulator. The force results indicated that the interference drag amounted to an increase of ten counts or about 3% of the wing-body drag for a two engine configuration at the nominal propeller operating conditions. However, at the higher swirl angles (11 deg vs. 7 deg nominally) the interference drag was favorable by about the same magnitude.

  11. Gasification of diesel oil in supercritical water for fuel cells

    NASA Astrophysics Data System (ADS)

    Pinkwart, Karsten; Bayha, Thomas; Lutter, Wolfgang; Krausa, Michael

    Experiments have demonstrated the reforming of hydrocarbons in supercritical water. The hydrocarbons were reformed in a continuously operated tubular V4A reactor. The influences of four different commercial steam reforming catalysts were analysed. The experimental results showed that n-decane can be converted to a hydrogen-rich gas. Furthermore, experiments with diesel oil showed the possibility of fuel conversion at low temperature with commercial steam reforming catalysts. Low temperatures and the use of catalysts lead to inhibition of coke formation during the process. The supercritical reforming offers the possibility of a new low temperature hydrocarbon conversion process to hydrogen for fuel cell applications.

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

    SciTech Connect

    1996-11-01

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

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

    PubMed

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

    2016-02-01

    With increasing construction of wastewater treatment plants and stricter policies, municipal sewage sludge (MSS) disposal has become a serious problem. Treatment of MSS in supercritical water (SCW) can avoid the pre-drying procedure and secondary pollution of conventional methods. SCW treatment methods can be divided into supercritical water gasification (SCWG), supercritical water partial oxidation (SCWPO) and supercritical water oxidation (SCWO) technologies with increasing amounts of oxidants. Hydrogen-rich gases can be generated from MSS by SCWG or SCWPO technology using oxidants less than stoichiometric ratio while organic compounds can be completely degraded by SCWO technology with using an oxidant excess. For SCWG and SCWPO technologies, this paper reviews the influences of different process variables (MSS properties, moisture content, temperature, oxidant amount and catalysts) on the production of gases. For SCWO technology, this paper reviews research regarding the removal of organics with or without hydrothermal flames and the changes in heavy metal speciation and risk. Finally, typical systems for handling MSS are summarized and research needs and challenges are proposed. PMID:26645649

  14. Supercritical water oxidation for destruction of polycyclic aromatic hydrocarbons

    SciTech Connect

    Kocher, B.S.; Fullerton, K.L.; Lee, S.

    1994-12-31

    Polycyclic aromatic hydrocarbons (PAHs) represent a large class of hydrocarbons that are considered hazardous to the environment. Large amount of PAHs have been dumped onto open ground in cases such as Town gas sites. These sites represent a major environmental liability due to the difficulty in removing them by conventional methods and the large amount of sites, more than 2,000. Supercritical water oxidation offers a unique method of both removing the contaminates and destroying them in a single stage processing step. The process utilizes the single phase mixture of water and oxygen at supercritical water conditions. This allows for the PAHs to be extracted and destroyed simultaneously. The reaction produces an effluent stream rich in carbon dioxide and water. Town gas soil containing 3.37 wt% contamination was ultra-cleaned in a 1-liter pilot plant to an environmentally acceptable level of less than 200 ppm.

  15. Large-eddy simulation of trans- and supercritical injection

    NASA Astrophysics Data System (ADS)

    Müller, H.; Niedermeier, C. A.; Jarczyk, M.; Pfitzner, M.; Hickel, S.; Adams, N. A.

    2016-07-01

    In a joint effort to develop a robust numerical tool for the simulation of injection, mixing, and combustion in liquid rocket engines at high pressure, a real-gas thermodynamics model has been implemented into two computational fluid dynamics (CFD) codes, the density-based INCA and a pressure-based version of OpenFOAM. As a part of the validation process, both codes have been used to perform large-eddy simulations (LES) of trans- and supercritical nitrogen injection. Despite the different code architecture and the different subgrid scale turbulence modeling strategy, both codes yield similar results. The agreement with the available experimental data is good.

  16. Heat Transfer Phenomena in Supercritical Water Nuclear Reactors

    SciTech Connect

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

    2007-10-03

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

  17. Process for treating effluent from a supercritical water oxidation reactor

    SciTech Connect

    Barnes, C.M.; Shapiro, C.

    1995-12-31

    The present invention relates generally to a method for treating and recycling the effluent from a supercritical water oxidation reactor and more specifically to a method for treating and recycling the effluent by expanding the effluent without extensive cooling. Supercritical water oxidation is the oxidation of fuel, generally waste material, in a body of water under conditions above the thermodynamic critical point of water. The current state of the art in supercritical water oxidation plant effluent treatment is to cool the reactor effluent through heat exchangers or direct quench, separate the cooled liquid into a gas/vapor stream and a liquid/solid stream, expand the separated effluent, and perform additional purification on gaseous, liquid, brine and solid effluent. If acid gases are present, corrosion is likely to occur in the coolers. During expansion, part of the condensed water will revaporize. Vaporization can damage the valves due to cavitation and erosion. The present invention expands the effluent stream without condensing the stream. Radionuclides and suspended solids are more efficiently separated in the vapor phase. By preventing condensation, the acids are kept in the much less corrosive gaseous phase thereby limiting the damage to treatment equipment. The present invention also reduces the external energy consumption, by utilizing the expansion step to also cool the effluent.

  18. Amphoteric reactions of supercritical water with coal models

    SciTech Connect

    Horiuchi, A.K.; Fish, H.T.; Mikita, M.A.

    1988-01-01

    For the past several years this laboratory has been studying water assisted coal liquefaction. Initial experiments were designed to determine whether water could replace all or part of the donor solvent in coal liquefaction. More recent work has focused upon the chemical reactions of coal models in supercritical water. For the past year efforts have centered upon the study of two distinct coal model compound systems (bibenzyls and benzyl phenyl ethers) with water under liquefaction conditions. This research is intended to further evaluate the chemical role of water above its critical temperature in the conversion of coal to a liquefaction product. Results are discussed.

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

    PubMed

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

    2016-06-01

    The organic wastes such as lignocellulosic biomass, municipal solid waste, sewage sludge and livestock manure have attracted attention as alternative sources of energy. Cattle manure, a waste generated in surplus amounts from the feedlot, has always been a chief environmental concern. This study is focused on identifying the candidacy of horse manure as a next generation feedstock for biofuel production through supercritical water gasification. The horse manure was gasified in supercritical water to examine the effects of temperature (400-600°C), biomass-to-water ratio (1:5 and 1:10) and reaction time (15-45min) at a pressure range of 23-25MPa. The horse manure and resulting biochar were characterized through carbon-hydrogen-nitrogen-sulfur (CHNS), inductively coupled plasma-mass spectrometry (ICP-MS), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscopy (SEM). The effects of alkali catalysts such as NaOH, Na2CO3 and K2CO3 at variable concentrations (1-2wt%) were investigated to maximize the hydrogen yields. Supercritical water gasification of horse manure with 2wt% Na2CO3 at 600°C and 1:10 biomass-to-water ratio for 45min revealed maximum hydrogen yields (5.31mmol/g), total gas yields (20.8mmol/g) with greater carbon conversion efficiency (43.1%) and enhanced lower heating value of gas products (2920kJ/Nm(3)). The manure-derived biochars generated at temperatures higher than 500°C also demonstrated higher thermal stability (weight loss <34%) and larger carbon content (>70wt%) suggesting their application in enhancing soil fertility and carbon sequestration. The results propose that supercritical water gasification could be a proficient remediation technology for horse manure to generate hydrogen-rich gas products. PMID:27067100

  20. Transpiring wall supercritical water oxidation test reactor design report

    SciTech Connect

    Haroldsen, B.L.; Ariizumi, D.Y.; Mills, B.E.; Brown, B.G.; Rousar, D.C.

    1996-02-01

    Sandia National Laboratories is working with GenCorp, Aerojet and Foster Wheeler Development Corporation to develop a transpiring wall supercritical water oxidation reactor. The transpiring wall reactor promises to mitigate problems of salt deposition and corrosion by forming a protective boundary layer of pure supercritical water. A laboratory scale test reactor has been assembled to demonstrate the concept. A 1/4 scale transpiring wall reactor was designed and fabricated by Aerojet using their platelet technology. Sandia`s Engineering Evaluation Reactor serves as a test bed to supply, pressurize and heat the waste; collect, measure and analyze the effluent; and control operation of the system. This report describes the design, test capabilities, and operation of this versatile and unique test system with the transpiring wall reactor.

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

    NASA Astrophysics Data System (ADS)

    Muftuoglu, Altan

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

  2. Conversion of hazardous materials using supercritical water oxidation

    DOEpatents

    Rofer, Cheryl K.; Buelow, Steven J.; Dyer, Richard B.; Wander, Joseph D.

    1992-01-01

    A process for destruction of hazardous materials in a medium of supercritical water without the addition of an oxidant material. The harzardous material is converted to simple compounds which are relatively benign or easily treatable to yield materials which can be discharged into the environment. Treatment agents may be added to the reactants in order to bind certain materials, such as chlorine, in the form of salts or to otherwise facilitate the destruction reactions.

  3. Acetic acid oxidation and hydrolysis in supercritical water

    SciTech Connect

    Meyer, J.C.; Marrone, P.A.; Tester, J.W.

    1995-09-01

    Acetic acid (CH{sub 3}COOH) hydrolysis and oxidation in supercritical water were examined from 425--600 C and 246 bar at reactor residence times of 4.4 to 9.8 s. Over the range of conditions studied, acetic acid oxidation was globally 0.72 {+-} 0.15 order in acetic acid and 0.27 {+-} 0.15 order in oxygen to a 95% confidence level, with an activation energy of 168 {+-} 21 kJ/mol, a preexponential factor of 10{sup 9.9{+-}1.7}, and an induction time of about 1.5 s at 525 C. Isothermal kinetic measurements at 550 C over the range 160 to 263 bar indicated that pressure or density did not affect the rate of acetic acid oxidation as much as was previously observed in the oxidation of hydrogen or carbon monoxide in supercritical water. Major products of acetic acid oxidation in supercritical water are carbon dioxide, carbon monoxide, methane, and hydrogen. Trace amounts of propenoic acid were occasionally detected. Hydrolysis or hydrothermolysis in the absence of oxygen resulted in approximately 35% conversion of acetic acid at 600 C, 246 bar, and 8-s reactor residence time. Regression of the limited hydrolysis runs assuming a reaction rate first-order in organic gave a global rate expression with a preexponential factor of 10{sup 4.4{+-}1.1} and an activation energy of 94 {+-} 17 kJ/mol.

  4. Method and apparatus for waste destruction using supercritical water oxidation

    DOEpatents

    Haroldsen, Brent Lowell; Wu, Benjamin Chiau-pin

    2000-01-01

    The invention relates to an improved apparatus and method for initiating and sustaining an oxidation reaction. A hazardous waste, is introduced into a reaction zone within a pressurized containment vessel. An oxidizer, preferably hydrogen peroxide, is mixed with a carrier fluid, preferably water, and the mixture is heated until the fluid achieves supercritical conditions of temperature and pressure. The heating means comprise cartridge heaters placed in closed-end tubes extending into the center region of the pressure vessel along the reactor longitudinal axis. A cooling jacket surrounds the pressure vessel to remove excess heat at the walls. Heating and cooling the fluid mixture in this manner creates a limited reaction zone near the center of the pressure vessel by establishing a steady state density gradient in the fluid mixture which gradually forces the fluid to circulate internally. This circulation allows the fluid mixture to oscillate between supercritical and subcritical states as it is heated and cooled.

  5. Simulation of a Supercritical Fluid Flow with Large Temperature Difference under the Assumption of Constant Pressure

    NASA Astrophysics Data System (ADS)

    Komurasaki, Satoko

    2015-11-01

    Eruption of geothermally heated water from the hydrothermal vent in deep oceans of depth over 2,000 meters is numerically simulated. The hydrostatic pressure of water is assumed to be over 200 atmospheres, and the temperature of heated water is occasionally more than 300°C. Under these conditions, a part of heated water can be in the supercritical state, and the physical properties can change significantly by the temperature. Particularly, thermal diffusivity at the critical temperature becomes so small, which prevents heat diffusion, and the temperature gradients can become high. Simulation of this kind of fluid flow can be carried out only by using a highly robust scheme. In this paper, a scheme for a highly-unsteady-flow computation is introduced, and a supercritical fluid flow with a large temperature difference is simulated at a constant pressure. In the computation, the compressible Navier-Stokes equations are solved using a method for the incompressible equations under constant pressure. The equations are approximated by the multidirectional finite difference method and KK scheme is used to stabilize the high-accuracy computation. This work was partially supported by Grant-in-Aid for Scientific Research from MEXT/JSPS (26610119).

  6. Supercritical Water Reactor Cycle for Medium Power Applications

    SciTech Connect

    BD Middleton; J Buongiorno

    2007-04-25

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

  7. Large Eddy Simulation of Cryogenic Injection Processes at Supercritical Pressure

    NASA Technical Reports Server (NTRS)

    Oefelein, Joseph C.; Garcia, Roberto (Technical Monitor)

    2002-01-01

    This paper highlights results from the first of a series of hierarchical simulations aimed at assessing the modeling requirements for application of the large eddy simulation technique to cryogenic injection and combustion processes in liquid rocket engines. The focus is on liquid-oxygen-hydrogen coaxial injectors at a condition where the liquid-oxygen is injected at a subcritical temperature into a supercritical environment. For this situation a diffusion dominated mode of combustion occurs in the presence of exceedingly large thermophysical property gradients. Though continuous, these gradients approach the behavior of a contact discontinuity. Significant real gas effects and transport anomalies coexist locally in colder regions of the flow, with ideal gas and transport characteristics occurring within the flame zone. The current focal point is on the interfacial region between the liquid-oxygen core and the coaxial hydrogen jet where the flame anchors itself.

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

    SciTech Connect

    Divilio, R.J.

    1998-08-01

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

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

    SciTech Connect

    Antal, M.J. Jr.; Xu, X.

    1998-08-01

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

  10. Reactions of inorganic nitrogen species in supercritical water

    SciTech Connect

    Dell`Orco, P.C.

    1994-12-31

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

  11. Separation of ionic species under supercritical water conditions

    SciTech Connect

    Li, L.; Gloyna, E.F.

    1999-04-01

    The unique characteristics of supercritical water (SCW) offer potentially attractive processing options that can be explored for reaction and separation purposes. While supercritical water oxidation (SCWO) can achieve high organic conversion efficiencies, low and relative solubilities of inorganic species in SCW may be further utilized for in situ separation of potential by-products from the SCWO process effluent. This paper describes a novel method for separating ionic species under SCW conditions. The concept is based on relative solubilities of different ionic species in SCW. Laboratory-scale demonstration tests were conducted with a Nylon monomer manufacturing process wastewater containing sodium hydroxide, sodium borate, carboxylic acids, and water. The process achieved (1) effective destruction (> 99%) of organic components in the wastewater; (2) selective precipitation of sodium (> 99.5%) as carbonates produced from oxidation of the organic components; and (3) efficient recovery of boron (> 90%) as boric acid in the reactor effluent. The sodium removal efficiency is governed by the solubilities of sodium carbonates in SCW and, therefore, can be directly improved by increasing process temperature. As a result of the temperature increase, both organic destruction and boron recovery efficiencies may be enhanced. This method of selective separation of ionic species in SCW has potential for a wide range of processing applications.

  12. Carbon-catalyzed gasification of organic feedstocks in supercritical water

    SciTech Connect

    Xu, X.; Matsumura, Y.; Stenberg, J.; Antal, M.J. Jr.

    1996-08-01

    Spruce wood charcoal, macadamia shell charcoal, coal activated carbon, and coconut shell activated carbon catalyze the gasification of organic compounds in supercritical water. Feedstocks studied in this paper include glycerol, glucose, cellobiose, whole biomass feedstocks (depithed bagasse liquid extract and sewage sludge), and representative Department of Defense (DoD) wastes (methanol, methyl ethyl ketone, ethylene glycol, acetic acid, and phenol). The effects of temperature, pressure, reactant concentration, weight hourly space velocity, and the type of catalyst on the gasification of glucose are reported. Complete conversion of glucose (22% by weight in water) to a hydrogen-rich synthesis gas was realized at a weight hourly space velocity (WHSV) of 22.2 h{sup {minus}1} in supercritical water at 600 C, 34.5 MPa. Complete conversions of the whole biomass feeds were also achieved at the same temperature and pressure. The destruction efficiencies for the representative DoD wastes were also high. Deactivation of the carbon catalyst was observed after 4 h of operation without swirl in the entrance region of the reactor, but the carbon gasification efficiency remained near 100% for more than 6 h when a swirl generator was employed in the entrance of the reactor.

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

    NASA Astrophysics Data System (ADS)

    Korzh, Raisa; Bortyshevskyi, Valerii

    2016-05-01

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

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

    PubMed

    Korzh, Raisa; Bortyshevskyi, Valerii

    2016-12-01

    The gasification of an aqueous suspension of lignite from Alexandria coalfield (Ukraine) under the supercritical pressure was studied. The initial rates of the formation of hydrogen, carbon dioxide and methane were evaluated. The mutually stimulating interaction of the components of "brown coal-water-mineral matter" system was shown due to the influence of nanoscaled water medium on the formation of dipole-inductive, dispersive and ionic associates. In the temperature range of 300-450 °C, the oxygen source for gaseous products of the lignite supercritical gasification is mainly ion-associative nanoclustered water. The source of hydrogen at the subcritical temperature is the organic part of brown coal. For the supercritical water, the source of H is the nanoscale medium with ion associates. The last ones were responsible for the further transformation of coal. PMID:27194442

  15. COAL CONVERSION WASTEWATER TREATMENT BY CATALYTIC OXIDATION IN SUPERCRITICAL WATER

    SciTech Connect

    Phillip E. Savage

    1999-10-18

    Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or re-used. Catalytic oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of phenol over different heterogeneous oxidation catalysts in supercritical water. More specifically, we examined the oxidation of phenol over a commercial catalyst and over bulk MnO{sub 2}, bulk TiO{sub 2}, and CuO supported on Al{sub 2} O{sub 3}. We used phenol as the model pollutant because it is ubiquitous in coal-conversion wastewaters and there is a large database for non-catalytic supercritical water oxidation (SCWO) with which we can contrast results from catalytic SCWO. The overall objective of this research project is to obtain the reaction engineering information required to evaluate the utility of catalytic supercritical water oxidation for treating wastes arising from coal conversion processes. All four materials were active for catalytic supercritical water oxidation. Indeed, all four materials produced phenol conversions and CO{sub 2} yields in excess of those obtained from purely homogeneous, uncatalyzed oxidation reactions. The commercial catalyst was so active that we could not reliably measure reaction rates that were not limited by pore diffusion. Therefore, we performed experiments with bulk transition metal oxides. The bulk MnO{sub 2} and TiO{sub 2} catalysts enhance both the phenol disappearance and CO{sub 2} formation rates during SCWO. MnO{sub 2} does not affect the selectivity to CO{sub 2}, or to the phenol dimers at a given phenol conversion. However, the selectivities to CO{sub 2} are increased and the selectivities to phenol dimers are decreased in the presence of TiO{sub 2} , which are desirable trends for a catalytic SCWO process. The role of the catalyst appears to be accelerating the rate of formation of

  16. Coal conversion wastewater treatment by catalytic oxidation in supercritical water

    SciTech Connect

    Phillip E. Savage

    1999-10-20

    Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or re-used. Catalytic oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of phenol over different heterogeneous oxidation catalysts in supercritical water. More specifically, the authors examined the oxidation of phenol over a commercial catalyst and over bulk MnO{sub 2}, bulk TiO{sub 2}, and CuO supported on Al{sub 2}O{sub 3}. They used phenol as the model pollutant because it is ubiquitous in coal-conversion wastewaters and there is a large database for non-catalytic supercritical water oxidation (SCWO) with which they can contrast results from catalytic SCWO. The overall objective of this research project is to obtain the reaction engineering information required to evaluate the utility of catalytic supercritical water oxidation for treating wastes arising from coal conversion processes. All four materials were active for catalytic supercritical water oxidation. Indeed, all four materials produced phenol conversions and CO{sub 2} yields in excess of those obtained from purely homogeneous, uncatalyzed oxidation reactions. The commercial catalyst was so active that the authors could not reliably measure reaction rates that were not limited by pore diffusion. Therefore, they performed experiments with bulk transition metal oxides. The bulk MnO{sub 2} and TiO{sub 2} catalysts enhance both the phenol disappearance and CO{sub 2} formation rates during SCWO. MnO{sub 2} does not affect the selectivity to CO{sub 2}, or to the phenol dimers at a given phenol conversion. However, the selectivities to CO{sub 2} are increased and the selectivities to phenol dimers are decreased in the presence of TiO{sub 2}, which are desirable trends for a catalytic SCWO process. The role of the catalyst appears to be accelerating the

  17. General corrosion properties of modified PNC1520 austenitic stainless steel in supercritical water as a fuel cladding candidate material for supercritical water reactor

    NASA Astrophysics Data System (ADS)

    Nakazono, Y.; Iwai, T.; Abe, H.

    2010-03-01

    The Super-Critical Water-cooled Reactor (SCWR) has been designed and investigated because of its high thermal efficiency and plant simplification. There are some advantages including the use of a single phase coolant with high enthalpy but there are numerous potential problems, particularly with materials. As the operating temperature of supercritical water reactor will be between 280°C and 620°C with a pressure of 25MPa, the selection of materials is difficult and important. Austenitic stainless steels were selected for possible use in supercritical water systems because of their corrosion resistance and radiation resistance. The PNC1520 austenitic stainless steel developed by Japan Atomic Energy Agency (JAEA) as a nuclear fuel cladding material for a Na-cooled fast breeder reactor. The corrosion data of PNC1520 in supercritical water (SCW) is required but does not exist. The purpose of the present study is to research the corrosion properties for PNC1520 austenitic stainless steel in supercritical water. The supercritical water corrosion test was performed for the standard PNC1520 (1520S) and the Ti-additional type of PNC1520 (1520Ti) by using a supercritical water autoclave. Corrosion tests on the austenitic 1520S and 1520Ti steels in supercritical water were performed at 400, 500 and 600°C with exposures up to 1000h. The amount of weight gain, weight loss and weight of scale were evaluated after the corrosion test in supercritical water for both austenitic steels. After 1000h corrosion test performed, the weight gains of both austenitic stainless steels were less than 2 g/m2 at 400°C and 500°C . But both weight gain and weight loss of 1520Ti were larger than those of 1520S at 600°C . By increasing the temperature to 600°C, the surface of 1520Ti was covered with magnetite formed in supercritical water and dissolution of the steel alloying elements has been observed. In view of corrosion, 1520S may have larger possibility than 1520Ti to adopt a

  18. Transpiring wall supercritical water oxidation reactor salt deposition studies

    SciTech Connect

    Haroldsen, B.L.; Mills, B.E.; Ariizumi, D.Y.; Brown, B.G.

    1996-09-01

    Sandia National Laboratories has teamed with Foster Wheeler Development Corp. and GenCorp, Aerojet to develop and evaluate a new supercritical water oxidation reactor design using a transpiring wall liner. In the design, pure water is injected through small pores in the liner wall to form a protective boundary layer that inhibits salt deposition and corrosion, effects that interfere with system performance. The concept was tested at Sandia on a laboratory-scale transpiring wall reactor that is a 1/4 scale model of a prototype plant being designed for the Army to destroy colored smoke and dye at Pine Bluff Arsenal in Arkansas. During the tests, a single-phase pressurized solution of sodium sulfate (Na{sub 2}SO{sub 4}) was heated to supercritical conditions, causing the salt to precipitate out as a fine solid. On-line diagnostics and post-test observation allowed us to characterize reactor performance at different flow and temperature conditions. Tests with and without the protective boundary layer demonstrated that wall transpiration provides significant protection against salt deposition. Confirmation tests were run with one of the dyes that will be processed in the Pine Bluff facility. The experimental techniques, results, and conclusions are discussed.

  19. Computer simulation of water reclamation processors

    NASA Technical Reports Server (NTRS)

    Fisher, John W.; Hightower, T. M.; Flynn, Michael T.

    1991-01-01

    The development of detailed simulation models of water reclamation processors based on the ASPEN PLUS simulation program is discussed. Individual models have been developed for vapor compression distillation, vapor phase catalytic ammonia removal, and supercritical water oxidation. These models are used for predicting the process behavior. Particular attention is given to methodology which is used to complete this work, and the insights which are gained by this type of model development.

  20. Large-eddy simulation of supercritical fluid flow and combustion

    NASA Astrophysics Data System (ADS)

    Huo, Hongfa

    The present study focuses on the modeling and simulation of injection, mixing, and combustion of real fluids at supercritical conditions. The objectives of the study are: (1) to establish a unified theoretical framework that can be used to study the turbulent combustion of real fluids; (2) to implement the theoretical framework and conduct numerical studies with the aim of improving the understanding of the flow and combustion dynamics at conditions representative of contemporary liquid-propellant rocket engine operation; (3) to identify the key design parameters and the flow variables which dictate the dynamics characteristics of swirl- and shear- coaxial injectors. The theoretical and numerical framework is validated by simulating the Sandia Flame D. The calculated axial and radial profiles of velocity, temperature, and mass fractions of major species are in reasonably good agreement with the experimental measurements. The conditionally averaged mass fraction profiles agree very well with the experimental results at different axial locations. The validated model is first employed to examine the flow dynamics of liquid oxygen in a pressure swirl injector at supercritical conditions. Emphasis is placed on analyzing the effects of external excitations on the dynamic response of the injector. The high-frequency fluctuations do not significantly affect the flow field as they are dissipated shortly after being introduced into the flow. However, the lower-frequency fluctuations are amplified by the flow. As a result, the film thickness and the spreading angle at the nozzle exit fluctuate strongly for low-frequency external excitations. The combustion of gaseous oxygen/gaseous hydrogen in a high-pressure combustion chamber for a shear coaxial injector is simulated to assess the accuracy and the credibility of the computer program when applied to a sub-scale model of a combustor. The predicted heat flux profile is compared with the experimental and numerical studies. The

  1. Energetic approach of biomass hydrolysis in supercritical water.

    PubMed

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

    2015-03-01

    Cellulose hydrolysis can be performed in supercritical water with a high selectivity of soluble sugars. The process produces high-pressure steam that can be integrated, from an energy point of view, with the whole biomass treating process. This work investigates the integration of biomass hydrolysis reactors with commercial combined heat and power (CHP) schemes, with special attention to reactor outlet streams. The innovation developed in this work allows adequate energy integration possibilities for heating and compression by using high temperature of the flue gases and direct shaft work from the turbine. The integration of biomass hydrolysis with a CHP process allows the selective conversion of biomass into sugars with low heat requirements. Integrating these two processes, the CHP scheme yield is enhanced around 10% by injecting water in the gas turbine. Furthermore, the hydrolysis reactor can be held at 400°C and 23 MPa using only the gas turbine outlet streams. PMID:25536511

  2. Thermophysical properties of supercritical water and bond flexibility

    NASA Astrophysics Data System (ADS)

    Shvab, I.; Sadus, Richard J.

    2015-07-01

    Molecular dynamics results are reported for the thermodynamic properties of supercritical water using examples of both rigid (TIP 4 P /2005 ) and flexible (TIP 4 P /2005 f ) transferable interaction potentials. Data are reported for pressure, isochoric and isobaric heat capacities, the thermal expansion coefficient, isothermal and adiabatic compressibilities, Joule-Thomson coefficient, speed of sound, self-diffusion coefficient, viscosities, and thermal conductivity. Many of these properties have unusual behavior in the supercritical phase such as maximum and minimum values. The effectiveness of bond flexibility on predicting these properties is determined by comparing the results to experimental data. The influence of the intermolecular potential on these properties is both variable and state point dependent. In the vicinity of the critical density, the rigid and flexible potentials yield very different values for the compressibilities, heat capacities, and thermal expansion coefficient, whereas the self-diffusion coefficient, viscosities, and thermal conductivities are much less potential dependent. Although the introduction of bond flexibility is a computationally expedient way to improve the accuracy of an intermolecular potential, it can be counterproductive in some cases and it is not an adequate replacement for incorporating the effects of polarization.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    PubMed

    Svanström, M; Modell, M; Tester, J

    2004-01-01

    Supercritical water oxidation (SCWO) oxidizes organic and biological materials virtually completely to benign products without the need for stack gas scrubbing. Heavy metals are recovered as stabilized solid, along with the sand and clay that is present in the feed. The technology has been under development for twenty years. The major obstacle to commercialization has been developing reactors that are not clogged by inorganic solid deposits. That problem has been solved by using tubular reactors with fluid velocities that are high enough to keep solids in suspension. Recently, system designs have been created that reduce the cost of processing sewage sludges below that of incineration. At 10 wt- % dry solids, sludge can be oxidized with virtually complete recovery of the sludge heating value as hot water or high-pressure steam. Liquid carbon dioxide of high purity can be recovered from the gaseous effluent and excess oxygen can be recovered for recycle. The net effect is to reduce the stack to a harmless vent with minimal flow rate of a clean gas. Complete simulations have been developed using physical property models that accurately simulate the thermodynamic properties of sub- and supercritical water in mixtures with O2, N2, CO2, and organics. Capital and operating cost estimates are given for sewage sludge treatment, which are less costly than incineration. The scenario of direct recovery of energy from sludges has inherent benefits compared to other gasification or liquefaction options. PMID:15259956

  5. Corrosion behavior of porous chromium carbide in supercritical water

    NASA Astrophysics Data System (ADS)

    Dong, Ziqiang; Chen, Weixing; Zheng, Wenyue; Guzonas, Dave

    2012-01-01

    The corrosion behavior of highly porous chromium carbide (Cr 3C 2) prepared by a reactive sintering process was characterized at temperatures ranging from 375 °C to 625 °C in a supercritical water environment with a pressure of 25-30 MPa. The test results show that porous chromium carbide is stable in SCW environments at temperatures under 425 °C, above which disintegration occurred. The porous carbide was also tested under hydrothermal conditions of pressures between 12 MPa and 50 MPa at constant temperatures of 400 °C and 415 °C, respectively. The pressure showed little effect on the stability of chromium carbide in the tests at those temperatures. The mechanism of disintegration of chromium carbide in SCW environments is discussed.

  6. Thermal decomposition of substituted phenols in supercritical water

    SciTech Connect

    Martino, C.J.; Savage, P.E.

    1997-05-01

    The thermal decomposition of cresols, hydroxybenzaldehydes, nitrophenols, and benzenediols was studied in dilute aqueous solutions and in the absence of oxygen at 460 C and 250 atm for residence times around 10 s. Thermolysis under these conditions produced conversions of less than 10% for o-, m-, and p-cresol, whereas hydroxybenzaldehydes and nitrophenols were much more reactive. Global rate expressions are reported for the thermolysis of each hydroxybenzaldehyde and nitrophenol isomer. Phenol was a major product from the decomposition of all of the substituted phenols studied. For a given substituent, ortho-substituted phenols reacted more rapidly than the other isomers. For a given substituted position, nitrophenols reacted more rapidly than hydroxybenzaldehydes, which in turn reacted more rapidly than cresols. These results demonstrate that the treatment of CHO- and NO{sub 2}-substituted phenols by oxidation in supercritical water will involve the oxidation of thermal decomposition products in addition to the oxidation of the original compounds.

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

    PubMed Central

    Fujioka, Kouki; Futamura, Yasuhiro; Shiohara, Tomoo; Hoshino, Akiyoshi; Kanaya, Fumihide; Manome, Yoshinobu; Yamamoto, Kenji

    2009-01-01

    Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life’s origin. PMID:19582225

  8. Prediction of physical properties of water under extremely supercritical conditions: a molecular dynamics study.

    PubMed

    Sakuma, Hiroshi; Ichiki, Masahiro; Kawamura, Katsuyuki; Fuji-ta, Kiyoshi

    2013-04-01

    The physical properties of water under a wide range of pressure and temperature conditions are important in fundamental physics, chemistry, and geoscience. Molecular simulations are useful for predicting and understanding the physical properties of water at phases extremely different from ambient conditions. In this study, we developed a new five-site flexible induced point charge model to predict the density, static dielectric constant, and transport properties of water in the extremely supercritical phase at high temperatures and pressures of up to 2000 K and 2000 MPa. The model satisfactorily reproduced the density, radial distribution function, static dielectric constant, reorientation time, and self-diffusion coefficients of water above the critical points. We also developed a database of the static dielectric constant, which is useful for discussing the electrical conductivity of aqueous fluids in the earth's crust and mantle. PMID:23574243

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

    PubMed

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

    2015-03-01

    In this study, 13 types of organic materials were oxidized using H2O2 in a continuous flow reactor under the condition of supercritical water. The effect of the operational parameters on the conversion of total organic carbon (TOC) and total nitrogen (TN) was investigated, and the resulting quality of treated water was analyzed. It was found that these materials were easily oxidized with a TOC conversion achieving 99% at temperature of 460 °C and TN conversion reaching 94% at temperature of 500 °C. Rice decomposition was rapid, with TOC and TN decomposition rates of 99% obtained within residence of 100 s at temperature of 460 °C. At temperature of 460 °C, pressure of 24 MPa, residence time of 100 s, and excess oxygen of 100%, the quality of treated water attained levels commensurate with China's Standards for Drinking Water Quality. Reaction rate equation parameters were obtained by fitting the experimental data to the differential equation obtained using the Runge-Kutta algorithm. The decrease of the TOC in water samples exhibited reaction orders of 0.95 for the TOC concentration and 0.628 for the oxygen concentration. The activation energy was 83.018 kJ/mol. PMID:25315932

  10. Extraction of polychlorinated biphenyl with supercritical carbon dioxide, sulfur hexafluoride and subcritical water.

    PubMed

    Pross, S; Gau, W; Wenclawiak, B W

    2000-05-01

    In the extraction of spiked PCB from soil, three extracting fluids were investigated: supercritical carbon dioxide (CO2), supercritical sulfur hexafluoride (SF6) and subcritical water. Among the tested fluids SF6 appeared to be appropriate especially for the extraction of low polar PCB. CO2 and water were found to be suitable for the quantitative extraction of all PCB. Water was judged as the best because of its low price, good availability and environmental safety. PMID:11227442

  11. Structure and Dynamics of Confined Water and CO2 in Clays under Supercritical Conditions

    NASA Astrophysics Data System (ADS)

    Glezakou, V.; Lee, M.; Schaef, T.; Loring, J.; Davidson, C.; McGrail, P.

    2013-12-01

    Carbon dioxide (CO2) driven enhanced gas recovery (EGR) from depleted fractured shale gas reservoirs has the potential for producing economic benefits and providing long term storage options for anthropogenic derived CO2 emissions. However key scientific processes related to CO2:CH4 exchange rates, mineral volume changes, organic mobility, and mineral stability in the presence of acid gas injections are not well understood. In this paper, we conduct atomistic simulations to examine interactions occurring between model clay minerals and supercritical CO2 equilibrated with water or brines to identify parameters controlling adsorption and desorption of gases. Integrated within these simulations are results derived from a set of newly developed experimental techniques designed to characterize physico-chemical reactions at reservoir conditions. In a series of cell optimizations under pressures relevant to sequestration scenarios, molecular simulations within the NVT and NPT ensembles with varying water/CO2 ratios showed a range of interlayer expansion for specific cation-saturated smectites. In conjunction with experimental in situ high pressure x-ray diffraction (HXRD), semi-quantitative concentrations of interlayer H2O and CO2 were established. For example, Ca saturated smectites maintaining sub-single to single hydration states (<1W to 1W), expand approximately 1.7-2.0 Å when exposed to anhydrous supercritical CO2. In contrast, for single to double hydration states (1W-2W), the simulations indicate formation of a quasi-single, metastable state, leading to a reduced interlayer spacing. Partial dehydration of the interlayer spacing while in contact with CO2 is due to a reduction of the interlayer cation coordination number. Structural analysis of the intercalated species shows an increase in the hydrogen bonding between waters during CO2 intercalation coincident with a decrease in the coordination population around the cations. Power spectra reveal rotationally

  12. Catalytic gasification of wet biomass in supercritical water

    SciTech Connect

    Antal, M.J. Jr.; Matsumura, Yukihiko; Xu, Xiaodong

    1995-12-31

    Wet biomass (water hyacinth, banana trees, cattails, green algae, kelp, etc.) grows rapidly and abundantly around the world. As a biomass crop, aquatic species are particularly attractive because their cultivation does not compete with land-based agricultural activities designed to produce food for consumption or export. However, wet biomass is not regarded as a promising feed for conventional thermochemical conversion processes because the cost associated with drying it is too high. This research seeks to address this problem by employing water as the gasification medium. Prior work has shown that low concentrations of glucose (a model compound for whole biomass) can be completely gasified in supercritical water at 600{degrees}C and 34.5 Wa after a 30 s reaction time. Higher concentrations of glucose (up to 22% by weight in water) resulted in incomplete conversion under these conditions. The gas contained hydrogen, carbon dioxide, carbon monoxide, methane, ethane, propane, and traces of other hydrocarbons. The carbon monoxide and hydrocarbons are easily converted to hydrogen by commercial technology available in most refineries. This prior work utilized capillary tube reactors with no catalyst. A larger reactor system was fabricated and the heterogeneous catalytic gasification of glucose and wet biomass slurry of higher concentration was studied to attain higher conversions.

  13. Subcritical and supercritical water oxidation of CELSS model wastes

    NASA Astrophysics Data System (ADS)

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

    Controlled-Ecological-Life-Support-System (CELSS) model wastes were wet-oxidized at temperatures from 250 to 500°C, i.e., below and above the critical point of water (374°C and 218 kg/cm2 or 21.4 MPa). A solution of ammonium hydroxide and acetic acid and a slurry of human urine, feces, and wipes were used as model wastes. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500°C, i.e., above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. Although the extent of nitrogen oxidation to nitrous oxide (N2O) and/or nitrogen gas (N2) increased with reaction temperature, most of the nitrogen was retained in solution as ammonia near 400°C. This important finding suggests that most of the nitrogen in the waste feed can be retained in solution as ammonia during oxidation at low supercritical temperatures and be subsequently used as a nitrogen source for plants in a CELSS while at the same time organic matter is almost completely oxidized to carbon dioxide and water. It was also found in this study the Hastelloy C-276 alloy reactor corroded during waste oxidation. The rate of corrosion was lower above than below the critical temperature for water.

  14. Destruction of nuclear organic waste by supercritical water oxidation. Scale-up of the process

    SciTech Connect

    Moussiere, S.; Roubaud, A.; Fournel, B.

    2007-07-01

    In order to design and then define appropriate dimensions for a supercritical oxidation reactor, a 2D and 3D simulation of the fluid dynamics and heat transfer during the oxidation process has been performed. The solver used is a commercial code, Fluent 6.2. The turbulent flow field in the reactor, created by the stirrer is taken into account with a k-omega model and a swirl imposed to the fluid. In the 3D case the rotation of the stirrer can be modeled thanks to the sliding mesh model. The reactivity of the system is taken into account with a classical combustion model EDC. Comparisons with experimental temperature measurements validate the ability of the CFD modeling to simulate the supercritical water oxidation process. Simulation results provide us a view inside the reactor on the flow, temperature fields and the oxidation localization and development. Results indicate that the flow can be considered as piston-like, heat transfers are strongly enhanced by the stirring. Hence the scaling up of the reactor volume, to reach a treatment capacity of 1 Kg/h of pure organics, can be done regarding the necessary residence times and temperature distribution needed for a complete destruction of the organic matter. (authors)

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  16. Destruction of explosives and rocket fuels by supercritical water oxidation

    SciTech Connect

    Dyer, R.B.; Buelow, S.J.; Harradine, D.M.; Robinson, J.M.; Foy, B.R.; Atencio, J.H.; Dell`Orco, P.C.; Funk, K.A.; McInroy, R.E.; Rofer, C.K.; Counce, D.A.; Trujillo, P.E. Jr.; Wander, J.D.

    1992-09-01

    Traditional methods for disposing of PEPs have been open burning or open detonation (OB/OD); however, regulatory agencies are likely to prohibit OB/OD because of the uncontrolled air emissions and soil contaminations. Likewise, controlled incineration carries a liability for air pollution because large quantities of NO{sub x} are produced in the conventional combustion chemistry of PEPS. Soil and ground water have already been contaminated with PEPs through normal operations at manufacturing plants and military bases. Incineration can be used for decontamination of these soils, with the associated liability for air pollution, but few satisfactory and economic methods exist for ground water decontamination. A clear need exists for improved disposal and destruction methods. The destruction of energetic materials, including propellants, explosives and pyrotechnics (PEPS) by oxidation in supercritical water is described. The focus is on the chemistry of the process. The destruction efficiencies and products of reaction contained in the aqueous and gaseous effluents of several representative PEPs are reported.

  17. Subcritical and supercritical water oxidation of CELSS model wastes

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  18. Destruction of explosives and rocket fuels by supercritical water oxidation

    SciTech Connect

    Dyer, R.B.; Buelow, S.J.; Harradine, D.M.; Robinson, J.M.; Foy, B.R.; Atencio, J.H.; Dell'Orco, P.C.; Funk, K.A.; McInroy, R.E.; Rofer, C.K.; Counce, D.A.; Trujillo, P.E. Jr. ); Wander, J.D. )

    1992-01-01

    Traditional methods for disposing of PEPs have been open burning or open detonation (OB/OD); however, regulatory agencies are likely to prohibit OB/OD because of the uncontrolled air emissions and soil contaminations. Likewise, controlled incineration carries a liability for air pollution because large quantities of NO{sub x} are produced in the conventional combustion chemistry of PEPS. Soil and ground water have already been contaminated with PEPs through normal operations at manufacturing plants and military bases. Incineration can be used for decontamination of these soils, with the associated liability for air pollution, but few satisfactory and economic methods exist for ground water decontamination. A clear need exists for improved disposal and destruction methods. The destruction of energetic materials, including propellants, explosives and pyrotechnics (PEPS) by oxidation in supercritical water is described. The focus is on the chemistry of the process. The destruction efficiencies and products of reaction contained in the aqueous and gaseous effluents of several representative PEPs are reported.

  19. Governing chemistry of cellulose hydrolysis in supercritical water.

    PubMed

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

    2015-03-01

    At extremely low reaction times (0.02 s), cellulose was hydrolyzed in supercritical water (T=400 °C and P=25 MPa) to obtain a sugar yield higher than 95 wt%, whereas the 5-hydroxymethylfurfural (5-HMF) yield was lower than 0.01 wt %. If the reaction time was increased to 1 s, the main product was glycolaldehyde (60 wt%). Independently of the reaction time, the yield of 5-HMF was always lower than 0.01 wt%. To evaluate the reaction mechanism of biomass hydrolysis in pressurized water, several parameters (temperature, pressure, reaction time, and reaction medium) were studied for different biomasses (cellulose, glucose, fructose, and wheat bran). It was found that the H(+) and OH(-) ion concentration in the reaction medium as a result of water dissociation is the determining factor in the selectivity. The reaction of glucose isomerization to fructose and the further dehydration to 5-HMF are highly dependent on the ion concentration. By an increase in the pOH/pH value, these reactions were minimized to allow control of 5-HMF production. Under these conditions, the retroaldol condensation pathway was enhanced, instead of the isomerization/dehydration pathway. PMID:25704124

  20. Experiments and numerical simulation of mixing under supercritical conditions

    NASA Astrophysics Data System (ADS)

    Schmitt, T.; Rodriguez, J.; Leyva, I. A.; Candel, S.

    2012-05-01

    Supercritical pressure conditions designate a situation where the working fluid pressure is above the critical point. Among these conditions, it is interesting to identify a transcritical range which corresponds to cases where the pressure is above the critical point, but the injection temperature is below the critical value. This situation is of special interest because it raises fundamental issues which have technological relevance in the analysis of flows in liquid rocket engines. This situation is here envisaged by analyzing the behavior of a nitrogen shear coaxial jet comprising an inner stream injected at temperatures close to the critical temperature and a coaxial flow at a higher temperature. Experiments are carried out both in the absence of external modulation and by imposing a large amplitude transverse acoustic field. Real gas large eddy simulations are performed for selected experiments. The combination of experiments and calculations is used to evaluate effects of injector geometry and operating parameters. Calculations retrieve what is observed experimentally when the momentum flux ratio of the outer to the inner stream J= (ρ _eu_e^2)/(ρ _iu_i^2) is varied. Results exhibit the change in flow structure and the development of a recirculation region when this parameter exceeds a critical value. The instantaneous flow patterns for different momentum flux ratios are used in a second stage to characterize the dynamical behavior of the flow in terms of power spectral density of velocity and density fluctuations. Results obtained under acoustic modulation provide insight into mixing enhancement of coaxial streams with a view of its possible consequences in high frequency combustion instabilities. It is shown in particular that the presence of strong acoustic modulations notably reduces the high density jet core length, indicating an increased mixing efficiency. This behavior is more pronounced when the jet is placed at the location of maximum transverse

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

    SciTech Connect

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

    2013-02-01

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

  2. Hazard classification for the supercritical water oxidation test bed. Revision 1

    SciTech Connect

    Ramos, A.G.

    1994-10-01

    A hazard classification of ``routinely accepted by the public`` has been determined for the operation of the supercritical water oxidation test bed at the Idaho National Engineering Laboratory. This determination is based on the fact that the design and proposed operation meet or exceed appropriate national standards so that the risks are equivalent to those present in similar activities conducted in private industry. Each of the 17 criteria for hazards ``routinely accepted by the public,`` identified in the EG and G Idaho, Inc., Safety Manual, were analyzed. The supercritical water oxidation (SCWO) test bed will treat simulated mixed waste without the radioactive component. It will be designed to operate with eight test wastes. These test wastes have been chosen to represent a broad cross-section of candidate mixed wastes anticipated for storage or generation by DOE. In particular, the test bed will generate data to evaluate the ability of the technology to treat chlorinated waste and other wastes that have in the past caused severe corrosion and deposition in SCWO reactors.

  3. Physical properties of rocks and aqueous fluids at conditions simulating near- and supercritical reservoirs

    NASA Astrophysics Data System (ADS)

    Kummerow, Juliane; Raab, Siegfried

    2016-04-01

    The growing interest in exploiting supercritical geothermal reservoirs calls for a thorough identification and understanding of physico-chemical processes occuring in geological settings with a high heat flow. In reservoir engineering, electrical sounding methods are common geophysical exploration and monitoring tools. However, a realistic interpretation of field measurements is based on the knowledge of both, the physical properties of the rock and those of the interacting fluid at defined temperature and pressure conditions. Thus, laboratory studies at simulated in-situ conditions provide a link between the field data and the material properties in the depth. The physico-chemical properties of fluids change dramatically above the critical point, which is for pure water 374.21 °C and 221.2 bar. In supercritical fluids mass transfer and diffusion-controlled chemical reactions are enhanced and cause mineral alterations. Also, ion mobility and ion concentration are affected by the change of physical state. All this cause changes in the electrical resistivity of supercritical fluids and may have considerable effects on the porosity and hydraulic properties of the rocks they are in contact with. While there are some datasets available for physical and chemical properties of water and single component salt solutions above their critical points, there exist nearly no data for electrical properties of mixed brines, representing the composition of natural geothermal fluids. Also, the impact of fluid-rock interactions on the electrical properties of multicomponent fluids in a supercritical region is scarcely investigated. For a better understanding of fluid-driven processes in a near- and supercritical geological environment, in the framework of the EU-funded FP7 program IMAGE we have measured (1) the electrical resistivity of geothermal fluids and (2) physical properties of fluid saturated rock samples at simulated in-situ conditions. The permeability and electrical

  4. Supercritical Water Nuclear Steam Supply System: Innovations In Materials, Neutronics & Thermal-Hydraulics

    SciTech Connect

    Mark Anderson; M.L. Corradini; K. Sridharan; P. WIlson; D. Cho; T.K. Kim; S. Lomperski

    2004-09-02

    In the 1990's supercritical light-water reactors were considered in conceptual designs. A nuclear reactor cooled by supercritical waster would have a much higher thermal efficiency with a once-through direct power cycle, and could be based on standardized water reactor components (light water or heavy water). The theoretical efficiency could be improved by more than 33% over that of other water reactors and could be simplified with higher reliability; e.g., a boiling water reactor without steam separators or dryers.

  5. Treatment of pulp mill sludges by supercritical water oxidation

    SciTech Connect

    Modell, M.

    1990-07-01

    Supercritical water oxidation (SCWO) is new process that can oxidize organics very effectively at moderate temperatures (400 to 650{degree}C) and high pressure (3700 psi). It is an environmentally acceptable alternative for sludge treatment. In bench scale tests, total organic carbon (TOC) and total organic halide (TOX) reductions of 99 to 99.9% were obtained; dioxin reductions were 95 to 99.9%. A conceptual design for commercial systems has been completed and preliminary economics have been estimated. Comparisons confirm that SCWO is less costly than dewatering plus incineration for treating pulp mill sludges. SCWO can also compete effectively with dewatering plus landfilling where tipping fees exceed $35/yd{sup 3}. In some regions of the US, tipping fees are now $75/yd{sup 3} and rising steadily. In the 1995 to 2000 time frame, SCWO has a good chance of becoming the method of choice. MODEC's objective is to bring the technology to commercial availability by 1993. 10 refs., 6 figs., 19 tabs.

  6. On the kinetics of phenol oxidation in supercritical water

    SciTech Connect

    Krajnc, M.; Levec, J.

    1996-07-01

    Phenol oxidation in supercritical water was carried out in a tubular laboratory-scale reactor operated at a temperature range of 380 C to 450 C and pressures between 230 and 265 bar. The phenol feed concentrations were between 500 and 1,000 mg/L, while oxygen was fed into the reactor at 50 to 1,000% of the stoichiometric amount needed to oxidize phenol completely to carbon dioxide. Phenol conversions from 16 to 96% were attained as the reactor residence times varied from 15 to 203 s. The oxidation obeys a parallel-consecutive reaction scheme that involves multi-ring, intermediate products such as phenoxyl-phenol, biphenol, dibenzo-dioxin, maleic acid, and succinic acid. Experimental results showed that the phenol disappearance rate is represented well by a power-law kinetic model in which the rate is proportional to the 0.4 power of the oxygen mole fraction and roughly linearly proportional to the phenol mole fraction. The pressure effect on the disappearance rate was appropriately accounted for by introducing the molar volume of the reaction mixture, which was readily calculated by an equation of state. Total organic carbon reduction can be estimated by a lumped kinetic equation. In the P-T region the activation energy of the phenol disappearance was 124.7 kJ/mol.

  7. Effect of supercritical water shell on cavitation bubble dynamics

    NASA Astrophysics Data System (ADS)

    Shao, Wei-Hang; Chen, Wei-Zhong

    2015-05-01

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

  8. Thermal decomposition of ammonium nitrate in supercritical water

    SciTech Connect

    Luan, Li; Proesmans, P.I.; Buelow, S.J.

    1996-10-01

    Thermal decomposition of neat NH{sub 4}NO{sub 3} has been the subject of many investigations over the past years. The reaction process is surprisingly complicated and depends largely on the reaction environment. For example, trace amounts of NH{sub 3}, HNO{sub 3} and H{sub 2}O are shown to affect the reaction significantly. In this research, NH{sub 4}NO{sub 3} decompostion was investigated in supercritical water. Reactions were evaluated in the presence of additional components such as organic compounds (CH{sub 3}OH, CH{sub 3}COOH, phenol), KN(NO{sub 2}){sub 2}, H{sub 2}O{sub 2}. Experiments were performed at varying temperatures, reaction times, NH{sub 4}NO{sub 3}, H{sub 2}O{sub 2} and organic compound concentrations. Gaseous, liquid and solid products were collected and analysed. The experimental results provided insight of the reaction chemistry which will be discussed in detail.

  9. Design requirements for the supercritical water oxidation test bed

    SciTech Connect

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

    1994-05-01

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

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

    SciTech Connect

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

    2013-07-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

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

    PubMed

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

    2015-12-01

    A continuous supercritical water oxidation reactor was designed and constructed to investigate the conversion of a feces simulant without the use of a co-fuel. The maximum reactor temperature and waste conversion was determined as a function of stoichiometric excess of oxygen in order to determine factor levels for subsequent investigation. 48% oxygen excess showed the highest temperature with full conversion. Factorial analysis was then used to determine the effects of feed concentration, oxygen excess, inlet temperature, and operating pressure on the increase in the temperature of the reacting fluid as well as a newly defined non-dimensional number, NJa representing heat transfer efficiency. Operating pressure and stoichiometric excess oxygen were found to have the most significant impacts on NJa. Feed concentration had a significant impact on fluid temperature increase showing an average difference of 46.4°C between the factorial levels. PMID:26210324

  13. RAS and LES Simulation of the supercritical flow over the waving bed

    NASA Astrophysics Data System (ADS)

    Fu, X.; Ma, H.; Heyman, J.; Mettra, F.; Liu, D.; Ancey, C.

    2013-12-01

    The phenomena of bed forms exist widely in the natural rivers and are still not fully understood. The detailed sediment dynamics near the bed is essential for this problem. However, the fluid dynamics near the bed, which drives the sediment motion, is not clear. In this talk, we focus on the fluid dynamics of supercritical flow over a sinusoidal wavy bed, especially around the wall region. This setup mimics anti-dunes morphology i.e. bedforms that are commonly found in steep mountain streams. In this case, the flow depth and the bedform amplitude have the same order of magnitude with the amplitude of the bedform. To study the detailed fluid flow, a 3-Dimensional numerical simulation of Navier-Stokes equations is performed. Two different models, Reynolds Average Simulation (RAS) and Large Eddy Simulation (LES), are used for the turbulence closure. The two models are validated with experiments carried out on a wavy bed. Particular attention is paid to the fluid shear stress on the wavy bed and the bedform equivalent roughness. LES shows more abilities for this problem. In future, various wavelength and amplitude of the sinus wave will be implemented so that new shear stress formulas and parameterization for the anti-dune roughness in shallow water equations will be proposed.

  14. Re-forming supercritical quasi-parallel shocks. I - One- and two-dimensional simulations

    NASA Technical Reports Server (NTRS)

    Thomas, V. A.; Winske, D.; Omidi, N.

    1990-01-01

    The process of reforming supercritical quasi-parallel shocks is investigated using one-dimensional and two-dimensional hybrid (particle ion, massless fluid electron) simulations both of shocks and of simpler two-stream interactions. It is found that the supercritical quasi-parallel shock is not steady. Instread of a well-defined shock ramp between upstream and downstream states that remains at a fixed position in the flow, the ramp periodically steepens, broadens, and then reforms upstream of its former position. It is concluded that the wave generation process is localized at the shock ramp and that the reformation process proceeds in the absence of upstream perturbations intersecting the shock.

  15. Structure and Performance of a 600MWe Supercritical CFB Boiler with Water Cooled Panels

    NASA Astrophysics Data System (ADS)

    Li, Y.; Nie, L.; Hu, X. K.; Yue, G. X.; Li, W. K.; We, Y. X.; Lu, J. F.; Che, D. F.

    The circulating fluidized bed (CFB) combustion technology is one of the approved clean combustion technologies, and the power supply efficiency can be improved combining with the supercritical technology. A 600MWe supercritical CFB boiler is introduced in this paper. This boiler is designed based on the success of 300 MWe CFB boilers, which has a single furnace with three cyclones without external heat exchangers. There are twin furnaces and twin air distributors in the boiler. The water walls of the twin furnace above dense bed combines to a common fence wall with some channels to balance the pressure of the two furnaces. The smooth tubes are adopted in membrane water wall with mixing header. Six cyclones are located beside the furnace as well as six loopseals and six external heat exchangers. The hydrodynamic characteristic of water wall is available with the modeling prediction. And the performance of the 600MWe supercritical CFB boiler is also investigated.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  17. Density functional simulations as a tool to probe molecular interactions in wet supercritical CO2

    SciTech Connect

    Glezakou, Vassiliki Alexandra; McGrail, B. Peter

    2013-06-03

    Recent advances in mixed Gaussian and plane wave algorithms have made possible the effective use of density functional theory (DFT) in ab initio molecular dynamics (AIMD) simulations for large and chemically complex models of condensed phase materials. In this chapter, we are reviewing recent progress on the modeling and characterization of co-sequestration processes and reactivity in wet supercritical CO2 (sc-CO2). We examine the molecular transformations of mineral and metal components of a sequestration system in contact with water-bearing scCO2 media and aim to establish a reliable correspondence between experimental observations and theory models with predictive ability and transferability of results in large scale geomechanical simulators. This work is funded by the Department of Energy, Office of Fossil Energy. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research located at Pacific Northwest National Laboratory. The Pacific Norhtwest National Laboratory (PNNL) is operated by Battelle for DOE under contract DE-AC06-76RL01830.

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

    NASA Technical Reports Server (NTRS)

    Meyer Sedej, M.

    1985-01-01

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

  19. Kinetic analysis for ammonia decomposition in supercritical water oxidation of sewage sludge

    SciTech Connect

    Goto, Motonobu; Shiramizu, Daisuke; Kodama, Akio; Hirose, Tsutomu

    1999-11-01

    Supercritical water oxidation was applied to the destruction of municipal excess sewage sludge. The reaction was carried out in a batch reactor with hydrogen peroxide as an oxidant in the temperature range of 723--823 K. Ammonia and acetic acid are found to be refractory intermediates in supercritical water oxidation of organic wastes. Ammonia concentration produced during the reaction was measured as a function of reaction time. The dynamic data were analyzed by a first-order kinetics. The reaction rate constant coincides with those reported in the literature.

  20. Oxidative decoupling mechanisms of monomer recovery from waste tires via partial supercritical water oxidation

    SciTech Connect

    Lanterman, H.B.; Kocher, B.S.; Lee, S.

    1996-12-31

    Ground waste tires can be oxidatively decomposed into recoverable useful chemical species via a controlled, partial supercritical water oxidation. The process feasibility has been demonstrated using a 1-liter semi-batch supercritical water oxidation system that is fabricated of Hastelloy C-276. The typical operating conditions are 370-400{degrees}C and 220-260 atm. The products include C{sub 1}-C{sub 10} hydrocarbons, including isoprene, the monomer of natural rubber. Possible oxidative decoupling mechanisms for the recovery of monomer and preliminary process engineering results are presented in this paper.

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

    NASA Astrophysics Data System (ADS)

    Lizon-A-Lugrin, Laure

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

  2. Partitioning of Organic Compounds between Crude Oil and Water under Supercritical CO2 Condition

    NASA Astrophysics Data System (ADS)

    Rod, K. A.; Wang, G.

    2015-12-01

    In recent years depleted oil reservoirs have received special interest as carbon storage reservoirs because of their potential to offset costs through collaboration with enhanced oil recovery projects. Leakage of the injected CO2 may occur either as supercritical CO2 or CO2-saturated (brine) water. The injected supercritical CO2 is a nonpolar solvent that can potentially mobilize the residual oil compounds into supercritical CO2 and brine water through phase partitioning. For detailed risk assessment of CO2 leakage, various models can be used to quantify the mass of organic contaminants transported from carbon storage sites to potential receptors such as potable aquifers, in which the partition coefficients of crude oil hydrocarbons between CO2/crude oil/brines for subsurface CO2 sequestration scenarios are the key parameters controlling the fate and transport of organic contaminants along the CO2 leakage pathways. However, the solubilities of many of the oil organic compounds in brines under supercritical CO2 condition have not been yet fully determined. In this study, we developed a novel method to accurately measure the partitioning of crude oil organic compounds (BTEX, PAHs, etc.) between supercritical CO2 and brines and to study the effects of temperature, pressure, salinity, and compound's cosolvency (solubility enhancement) on the partitioning behavior of oil organic compounds along the various CO2 leakage paths in the subsurface.

  3. Gasification characteristics of an activated carbon catalyst during the decomposition of hazardous waste materials in supercritical water

    SciTech Connect

    Matsumura, Yukihiko; Nuessle, F.W.; Antal, M.J. Jr.

    1996-10-01

    Recently, carbonaceous materials were proved to be effective catalysts for hazardous waste decomposition in supercritical water. Gasification of the carbonaceous catalyst itself is also expected, however, under supercritical conditions. Thus, it is essential to determine the gasification rate of the carbonaceous materials during this process to determine the active lifetime of the catalysts. For this purpose, the gasification characteristics of granular coconut shell activated carbon in supercritical water alone (600-650{degrees}C, 25.5-34.5 MPa) were investigated. The gasification rate at subatmospheric pressure agreed well with the gasification rate at supercritical conditions, indicating the same reaction mechanism. Methane generation under these conditions is via pyrolysis, and thus is not affected by the water pressure. An iodine number increase of 25% was observed as a result of the supercritical water gasification.

  4. Simulation of supercritical flows in rocket-motor engines: application to cooling channel and injection system

    NASA Astrophysics Data System (ADS)

    Ribert, G.; Taieb, D.; Petit, X.; Lartigue, G.; Domingo, P.

    2013-03-01

    To address physical modeling of supercritical multicomponent fluid flows, ideal-gas law must be changed to real-gas equation of state (EoS), thermodynamic and transport properties have to incorporate dense fluid corrections, and turbulence modeling has to be reconsidered compared to classical approaches. Real-gas thermodynamic is presently investigated with validation by NIST (National Institute of Standards and Technology) data. Two major issues of Liquid Rocket Engines (LRE) are also presented. The first one is the supercritical fluid flow inside small cooling channels. In a context of LRE, a strong heat flux coming from the combustion chamber (locally Φ ≈ 80 MW/m2) may lead to very steep density gradients close to the wall. These gradients have to be thermodynamically and numerically captured to properly reproduce in the simulation the mechanism of heat transfer from the wall to the fluid. This is done with a shock-capturing weighted essentially nonoscillatory (WENO) numerical discretization scheme. The second issue is a supercritical fluid injection following experimental conditions [1] in which a trans- or supercritical nitrogen is injected into warm nitrogen. The two-dimensional results show vortex structures with high fluid density detaching from the main jet and persisting in the low-speed region with low fluid density.

  5. TREATMENT AND PRODUCT RECOVERY: SUPERCRITICAL WATER OXIDATION OF NYLON MONOMER MANUFACTURING WASTE

    EPA Science Inventory

    EPA GRANT NUMBER: R822721C569
    Title: Treatment and Product Recovery: Supercritical Water Oxidation of Nylon Monomer Manufacturing Waste
    Investigator: Earnest F. Gloyna
    Institution: University of Texas at Austin
    EPA Project Officer:<...

  6. Treatment of coal and formic acid mixtures with water at supercritical parameters

    SciTech Connect

    M.R. Predtechenskii; M.V. Pukhovoi; A.N. Smal; A.O. Uuemaa

    2007-08-15

    The treatment of coals of various degrees of metamorphism in supercritical water (SCW) over the temperature region 380-800{sup o}C was studied. The possibility of obtaining strong agglomerates from the powders of long-flame and oxidized fat noncoking coals by treatment in SCW was demonstrated. The strength of agglomerates was commensurable with the strength of lump coal.

  7. Separation of saturated hydrocarbons from coal by treatment with water at supercritical parameters

    SciTech Connect

    M.R. Predtechenskiy; M.V. Pukhovoy

    2008-10-15

    The treatment of coals of various degrees of metamorphism in supercritical water (SCW) over the temperature region 380-800{sup o}C was studied. The yields and compositions of liquid products obtained by treatment in SCW were determined. These data were compared with the results of the semicoking of the above coals.

  8. Case study on the destruction of organic dyes in supercritical water

    SciTech Connect

    LaJeunesse, C.A.; Rice, S.F.

    1994-11-01

    Organic dyes, which were used in Navy shells to mark ships and structures, need to be disposed of without burning. A study was undertaken to assess the feasibility of using supercritical water oxidation to destroy organic dyes. Experimental destruction efficiencies, product analyses, and process configuration are reported.

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

    NASA Astrophysics Data System (ADS)

    Karmiol, Zachary

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

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

    SciTech Connect

    Steeper, R.R.

    1996-01-01

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

  11. First Principles Simulations fo the Supercritical Behavior of Ore Forming Fluids

    SciTech Connect

    Weare, John H

    2013-04-19

    measured directly. However, the number of 2nd shell water molecules predicted by the simulation is consistent with experimental estimates. Tetrahedral bulk water coordination reappears just after the 2nd shell. Simulations with 128 waters are close to the maximum size that can effectively be performed with present day methods. While the time scale of our simulation are not long enough to observe transfers of waters from the 1st to the 2nd shell, we do see transfers occurring on a picosecond time scale between the 2nd shell and 3rd shell via an associative mechanism. This is faster than, but consistent with, the results of measurements on the more tightly bound Cr3+ system. For high temperature simulations, proton transfers occur in the solvation shells leading to transient hydrolysis species. The reaction coordinate for proton transfer involves the coordinates of neighboring solvent waters as in the Grotis mechanism for proton transfer in bulk water. Directly removing a proton from the hexaqua Al3+ ion leads to a much more labile solvation shell and to a five coordinated Al3+ ion. This is consistent with very recent rate measurements of ligand exchange and the conjugate base labilization effect. For the Al3+-H2O system results for high but subcritical temperatures are qualitatively similar to room temperature simulations. However, preliminary simulations for supercritical temperatures (750K) suggest that there may be a dramatic change in behavior in the hydration structure of ions for these temperatures. For transition metal ions the presence of d valence electrons plays a significant role in the behavior of the system. Our preliminary results for the Fe3+ ion suggest that this ion which is larger radius than the Al3+ ion has somewhat less rigid 1st and 2nd solvation shell. II. Gibbs Ensemble Monte Carlo Simulation of Vapor/Liquid and Metastable Liquid/Liquid Phase Equilibria in the CO2-CH4-N2 System Many fluid inclusions have compositions in the system CO2-CH4-N2

  12. Startup Thermal Considerations for Supercritical-Pressure Light Water-Cooled Reactors

    SciTech Connect

    Nakatsuka, Toru; Oka, Yoshiaki; Koshizuka, Seiichi

    2001-06-15

    Supercritical-pressure light water-cooled reactors (SCRs) are innovative systems aimed at high efficiency and cost reduction. The once-through direct-cycle plant system is the leading system of fossil-fired power plants (FPPs). Estimates of the coolability and necessary sizes of the SCR startup systems, sequences, and required equipment for startup are investigated with reference to supercritical FPPs. There are two types of supercritical boilers. One is a constant pressure boiler, and the other is a variable pressure boiler.First, startup of the constant pressure boiler is examined. The reactor starts at a supercritical pressure. A startup bypass system consisting of a flash tank and pressure-reducing valves is required. Second, startup of the variable pressure boiler is investigated. The reactor starts at a subcritical pressure, and the pressure increases with the load. A steam-water separator and a drain tank are required for startup.The results of computer calculations show that with both constant pressure and variable pressure startup, the peak cladding temperature does not exceed the operating limit through startup, and both startup sequences are feasible. The sizes of the components required for the startup systems are assessed. To simplify the plant system and to reduce the component size, variable pressure startup with steam separators in the bypass line appears desirable.

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

    SciTech Connect

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

    2005-02-13

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

  14. Fast-Geomimicking using Chemistry in Supercritical Water.

    PubMed

    Dumas, Angela; Claverie, Marie; Slostowski, Cédric; Aubert, Guillaume; Careme, Cristel; Le Roux, Christophe; Micoud, Pierre; Martin, François; Aymonier, Cyril

    2016-08-16

    Herein we introduce a powerful and fast method to produce nanominerals using a bottom up approach. The supercritical hydrothermal flow synthesis is exploited to produce model nanominerals by mimicking natural environments at high temperatures under pressure. This innovative concept is demonstrated with the talc synthesis; this represents a major technical breakthrough since it allows decreasing the mineral-synthesis time from tens of hours to tens of seconds. Through this example, we show these nanominerals exhibit new crystal-chemistry signals and new properties. This approach provides a means to reproduce the early stages of formation of minerals in different natural environments from sedimentary environments (low temperature and pressure) to hydrothermal/metamorphic environments (high temperature and high pressure). PMID:27321954

  15. Water solubility measurements in supercritical fluids and high-pressure liquids using near-infrared spectroscopy

    SciTech Connect

    Jackson, K.; Bowman, L.E.; Fulton, J.L.

    1995-07-15

    A small amount of water added to a supercritical fluid can greatly increase the solubility of polar species in nonpolar fluids. These modified supercritical solutions significantly expand the use of the fluids in separations and reactions. In order to successfully utilize these systems, information on the miscibility or solubility of water in the fluid is required. Often solubility data are not available for water in a supercritical fluid under a given set of temperature and pressure conditions, and a costly set of equipment must be assembled in order to make these measurements. A relatively fast and inexpensive technique to measure water solubilities using a simple long path length optical cell in an FT-IR spectrometer is described. This technique is also applicable to common and newly developed refrigerants where water solubilities are often unknown at temperatures much above ambient. In this paper, water solubility data in carbon dioxide and two types of refrigerants (chlorodifluoromethane, R22; 1,1,1,2-tetrafluoroethane, R134a) are presented for temperatures from approximately 40 to 110{degree}C and pressures from approximately 10 to 344.8 bar. 26 refs., 6 figs., 4 tabs.

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

    DOE PAGESBeta

    Hu, Po; Wilson, Paul

    2014-01-01

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

  17. Evolution of the core physics concept for the Canadian supercritical water reactor

    SciTech Connect

    Pencer, J.; Colton, A.; Wang, X.; Gaudet, M.; Hamilton, H.; Yetisir, M.

    2013-07-01

    The supercritical water cooled reactor (SCWR) is one of the advanced reactor concepts chosen by the GEN-IV International Forum (GIF) for research and development efforts. Canada's contribution is the Canadian SCWR, a heavy water moderated, pressure tube supercritical light water cooled reactor. Recent developments in the SCWR lattice and core concepts, primarily the introduction of a large central flow tube filled with coolant combined with a two-ring fuel assembly, have enabled significant improvements compared to earlier concepts. These improvements include a reduction in coolant void reactivity (CVR) by more than 10 mk, and an almost 40% increase in fuel exit burnup, which is achieved via balanced power distribution between the fuel pins in the fuel assembly. In this paper the evolution of the physics concept is reviewed, and the present lattice and core physics concepts are presented.

  18. Gasification of sewage sludge and other biomass for hydrogen production in supercritical water

    SciTech Connect

    Xu, X.; Antal, M.J. Jr.

    1998-12-31

    Digested sewage sludge and other biomass such as wood sawdust can be mixed with a corn starch gel to form a viscous paste. The paste can be delivered to a supercritical flow reactor by means of a cement pump. Different types of feedstocks are used in this work sewage sludge (up to 7.69 wt%) mixed in the corn starch paste. When rapidly heated in a flow reactor at pressures above the critical pressure of water (22 MPa) the paste vaporizes. A packed bed of carbon catalyst in the reactor operating at 650 C causes the tarry vapors to react with water, producing hydrogen, carbon dioxide, and some methane with a trace of carbon monoxide. Thus the authors describe a practical method for the total, supercritical steam reforming of biomass to produce hydrogen at high pressure. The steam reforming process produces effectively no tar. Its only products are a hydrogen rich gas, and a clean water, which can be recycled.

  19. Incorporation of parametric uncertainty into complex kinetic mechanisms: Application to hydrogen oxidation in supercritical water

    SciTech Connect

    Phenix, B.D.; Dinaro, J.L.; Tatang, M.A.; Tester, J.W.; Howard, J.B.; McRae, G.J.

    1998-01-01

    In this study, uncertainty analysis is applied to a supercritical water hydrogen oxidation mechanism to determine the effect of uncertainties in reaction rate constants and species thermochemistry on predicted species concentrations. Forward rate constants and species thermochemistry are assumed to be the sole contributors to uncertainty in the reaction model with all other model parameters and inputs treated as deterministic quantities. Uncertainty propagation is performed using traditional Monte Carlo (MC) simulation and a new, more computationally efficient, probabilistic collocation method called the Deterministic Equivalent Modeling Method (DEMM). The results of both analyses show that there is considerable uncertainty in all predicted species concentrations. The predicted H{sub 2} and O{sub 2} concentrations vary {+-}70% from their median values. Similarly, the HO{sub 2} concentration ranges from +90 to {minus}70% of its median, while the H{sub 2}O{sub 2} concentration varies by +180 to {minus}80%. In addition, the DEMM methodology identified two key model parameters, the standard-state heat of formation of HO{sub 2} radical and the forward rate constant for H{sub 2}O{sub 2} dissociation, as the largest contributors to the uncertainty in the predicted hydrogen and oxygen species concentrations. The analyses further show that the change in model predictions due to the inclusion of real-gas effects, which are potentially important for SCWO process modeling, is small relative to the uncertainty introduced by the model parameters themselves.

  20. RPCSIM-SCO2 (Reactor Power and Control SIMulator for Supercritical CO2)

    SciTech Connect

    Wright, Steven A.

    2012-09-12

    The RPCSIM-SCO2 code performs a dynamic simulation of a supercritical CO2 (carbon dioxide) Brayton cycle loop. The code is based on the MathLabTM program SimulinkTM from Mathworks. The Supercritical CO2 (S-CO2) model uses direct calls to the National Institute of Standards Refprop 9.0 Fortran library for the Equation-of-State (EOS) model for the CO2 working fluid (Lemmon, 2010). The calls to Refprop are made in the form of Simulink s-Functions that use a C interface to directly call the compiled Refprop fortran program library functions. Minor changes to the code can be made to use other working fluids. The code is intended to be used to perform many different types of dynamic cycle analysis for supercritical CO2 power producing systems. The code will calculate the transient temperature and pressure and all other thermodynamic properties at the inlet and outlet of each component given user supplied inputs such as rotor shaft speed, and heater power.

  1. RPCSIM-SCO2 (Reactor Power and Control SIMulator for Supercritical CO2)

    Energy Science and Technology Software Center (ESTSC)

    2012-09-12

    The RPCSIM-SCO2 code performs a dynamic simulation of a supercritical CO2 (carbon dioxide) Brayton cycle loop. The code is based on the MathLabTM program SimulinkTM from Mathworks. The Supercritical CO2 (S-CO2) model uses direct calls to the National Institute of Standards Refprop 9.0 Fortran library for the Equation-of-State (EOS) model for the CO2 working fluid (Lemmon, 2010). The calls to Refprop are made in the form of Simulink s-Functions that use a C interface tomore » directly call the compiled Refprop fortran program library functions. Minor changes to the code can be made to use other working fluids. The code is intended to be used to perform many different types of dynamic cycle analysis for supercritical CO2 power producing systems. The code will calculate the transient temperature and pressure and all other thermodynamic properties at the inlet and outlet of each component given user supplied inputs such as rotor shaft speed, and heater power.« less

  2. Sorption Phase of Supercritical CO2 in Silica Aerogel: Experiments and Mesoscale Computer Simulations

    SciTech Connect

    Rother, Gernot; Vlcek, Lukas; Gruszkiewicz, Miroslaw {Mirek} S; Chialvo, Ariel A; Anovitz, Lawrence {Larry} M; Banuelos, Jose Leo; Wallacher, Dirk; Grimm, Nico; Cole, David

    2014-01-01

    Adsorption of supercritical CO2 in nanoporous silica aerogel was investigated by a combination of experiments and molecular-level computer modeling. High-pressure gravimetric and vibrating tube densimetry techniques were used to measure the mean pore fluid density and excess sorption at 35 C and 50 C and pressures of 0-200 bar. Densification of the pore fluid was observed at bulk fluid densities below 0.7 g/cm3. Far above the bulk fluid density, near-zero sorption or weak depletion effects were measured, while broad excess sorption maxima form in the vicinity of the bulk critical density region. The CO2 sorption properties are very similar for two aerogels with different bulk densities of 0.1 g/cm3 and 0.2 g/cm3, respectively. The spatial distribution of the confined supercritical fluid was analyzed in terms of sorption- and bulk-phase densities by means of the Adsorbed Phase Model (APM), which used data from gravimetric sorption and small-angle neutron scattering experiments. To gain more detailed insight into supercritical fluid sorption, large-scale lattice gas GCMC simulations were utilized and tuned to resemble the experimental excess sorption data. The computed three-dimensional pore fluid density distributions show that the observed maximum of the excess sorption near the critical density originates from large density fluctuations pinned to the pore walls. At this maximum, the size of these fluctuations is comparable to the prevailing pore sizes.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  4. Molecular dynamics investigation of the various atomic force contributions to the interfacial tension at the supercritical CO2-water interface.

    PubMed

    Zhao, Lingling; Lin, Shangchao; Mendenhall, Jonathan D; Yuet, Pak K; Blankschtein, Daniel

    2011-05-19

    Sequestration of carbon dioxide (CO(2)) in deep, geological formations involves the injection of supercritical CO(2) into depleted reservoirs containing fluids such as brine or oil. The interfacial tension (IFT) between supercritical CO(2) and the reservoir fluid is an important contribution to the sequestration efficiency. In turn, the IFT is a complex function of the reservoir fluid phase composition, the molecular structure of each reservoir fluid component, and environmental conditions (i.e., temperature and pressure). Molecular dynamics simulations can be used to probe the dependence of the IFT on these factors, since the IFT can be calculated directly from the simulated atomic forces and velocities at system equilibrium using the mechanical definition of the IFT. Here, we examine the contribution of each type of atomic force to the IFT, including bonded and nonbonded forces, as quantified by the anisotropy of the atomic virial tensor. In particular, we first examine a supercritical CO(2)-pure liquid water interface, at typical reservoir conditions (temperature of 343 K and pressure of 20 MPa), as a reference state against which CO(2)-brine systems can be compared. In this system, we note that the interactions between water molecules and between CO(2) molecules ("self" interactions) contribute positively to the IFT, while the interactions between water and CO(2) molecules ("cross" interactions) contribute negatively to the IFT. We find that the magnitude of the water "self" interactions is the dominant contribution. In terms of specific types of forces, we find that nonbonded electrostatic (QQ), bonded angle-bending, and bonded bond-stretching interactions contribute positively to the IFT, while nonbonded Lennard-Jones (LJ) interactions contribute negatively to the IFT. We also find that the balance between the LJ interactions and the bond-stretching interactions, in particular, plays a significant role in determining the magnitude of the IFT. Using

  5. A supercritical water oxidation reactor: The Material Evaluations Reactor (MeR)

    SciTech Connect

    LaJeunesse, C.A.; Rice, S.F.; Bartel, J.J.; Kelley, M.; Seibel, C.A.; Hoffa, L.G.; Eklund, T.F.; Odegard, B.C.

    1992-02-01

    The paper describes the construction and control details of a supercritical water oxidation (SCWO) flow reactor. These details include a description of the Quality Function Deployment process that identified the system requirements and resource allocations, an overview of the SCWO process, and an in-depth description of the reactor itself including both physical and operational design. Supercritical water oxidation to destroy aqueous organic waste is a relatively new technology discovered about twelve years ago at the Massachusetts Institute of Technology. It is not commercialized presently, but shows promise for detoxifying wastes in an efficient, cost-competitive, and environmentally safe manner. Supercritical water oxidation occurs at moderate temperatures and pressures where the ability of water to dissolve hydrocarbons is greatly enhanced. Depending on the feed stream and residence time, the dissolved hydrocarbon reacts with an oxidizer to produce innocuous combustion products. We also report the development of an optical component for this flow reactor that permits the use of laser-based diagnostics, specifically spontaneous Raman scattering, to directly probe the reacting flow. Optical accessibility allows the determination of the concentration of these reactants and the chemical kinetics of the reaction in-situ -- the spatial dependence of mechanical processes, in particular corrosion and deposition, that affect the long term reliability of reactors can also be investigated.

  6. Water hammer simulator

    SciTech Connect

    Sinha, S.K.; Madia, J.; Dixon, S.

    1995-11-01

    The Consolidated Edison Company of New York, Inc. (Con Edison) has constructed a first-of-a-kind water hammer events simulator for use at its training center. The Learning Center, Con Edison`s central training facility, intends to use the simulator as an educational tool to demonstrate the various mechanisms of the water hammer phenomenon to power plant designers, engineers and operators. The water hammer phenomenon has been studied extensively for the past 15 years for the nuclear industry. However, the acknowledge of the various water hammer mechanisms and the measures to prevent or mitigate water hammer have not been widely disseminated among the operators of fossil-fueled power plants. Con Edison personnel who operate the various generation stations and the New York City steam distribution systems are expected to benefit from the new simulator. Knowledge gained from interacting with the simulator will be very important in helping the Con Edison prevent, mitigate, or accommodate water hammer at its facilities. The water hammer simulator was fabricated in Con Edison`s central machine shop. Details of the design and construction of the simulator were finalized in consultation with Creare, Inc., an engineering research firm, located in Hanover, New Hampshire. The simulator seeks to recreate the essential features of water hammer in steam mines following the buildup of cold (subcooled) water by condensation and steam-water interaction. This paper describes the fabrication, design, testing, and operation of the Con Edison water hammer simulator. A discussion of how Con Edison plans to use the facility at The Learning Center is included.

  7. Supercritical fluid extraction of chemical warfare agent simulants from soil.

    PubMed

    Griest, W H; Ramsey, R S; Ho, C H; Caldwell, W M

    1992-05-29

    Chemical warfare agent simulants are efficiently recovered from 2-ppm spikes in 1 g of Rocky Mountain Arsenal Standard Soil using methanol-carbon dioxide (5:95) at 300 atm for 2 min at 60 degrees C. Recoveries (n = 3) were 79 +/- 23% for dimethylmethylphosphonate, 93 +/- 14% for 2-chloroethylethyl sulfide, 92 +/- 13% for diisopropylfluorophosphate and 95 +/- 17% for diisopropylmethylphosphonate. Recoveries are higher than, but less precise than those achieved from a 5-min ultrasonic micro-scale extraction using methanol. Much less laboratory waste is generated than the current standard organic solvent extraction method (33 g of soil shaken with 100 ml of chloroform). PMID:1400849

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  9. Oxidation reaction of high molecular weight carboxylic acids in supercritical water.

    PubMed

    Jin, Fangming; Moriya, Takehiko; Enomoto, Heiji

    2003-07-15

    Stearic acid, being a model compound of high molecular weight carboxylic acids, was oxidized in a batch reactor by changing the oxygen supply with an insufficient oxygen supply at a constant reaction time at 420 degrees C. On the basis of the intermediate products identified by GC/MS, NMR, and HPLC analyses and the free-radical reaction mechanism, the oxidation pathways of high molecular weight carboxylic acids in supercritical water are discussed. The reaction of carboxylic acids in supercritical water proceeds with the consecutive oxidation of higher molecular weight carboxylic acids to lower molecular weight carboxylic acids through several major pathways. The attack of the hydroxyl radical occurs not only at the carbons in alpha-, beta-, gamma-positions to a --COOH group but also at the carbons ((omega-1)-carbon and/or omega-carbon) far in the alkyl chain from a --COOH group, which may lead to the formation of dicarboxylic acids. PMID:12901673

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

    PubMed

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

    2016-01-01

    Biomass-derived ethyl lactate is a green solvent with a growing market as the replacement for petroleum-derived toxic organic solvents. Here we report, for the first time, the production of ethyl lactate directly from cellulose with the mesoporous Zr-SBA-15 silicate catalyst in a supercritical mixture of ethanol and water. The relatively strong Lewis and weak Brønsted acid sites on the catalyst, as well as the surface hydrophobicity, were beneficial to the reaction and led to synergy during consecutive reactions, such as depolymerization, retro-aldol condensation, and esterification. Under the optimum reaction conditions, ∼33 % yield of ethyl lactate was produced from cellulose with the Zr-SBA-15 catalyst at 260 °C in supercritical 95:5 (w/w) ethanol/water. PMID:26685114

  11. Partial oxidative gasification of municipal sludge in subcritical and supercritical water.

    PubMed

    Xu, Z R; Zhu, W; Htar, Swe Hlaing

    2012-06-01

    Subcritical and supercritical water gasification of dewatered sewage sludge obtained from a typical municipal wastewater treatment plant was investigated in a one-litre high-pressure autoclave at temperatures of 300-400 degrees C and pressures of 17.5-23.5 MPa. The sludge (without catalyst) was gasified at subcritical and supercritical water conditions, with different reaction times ranging from 30 to 60 min. The results showed that gaseous product yield increased with increasing temperature and reaction time. Gas products consisted primarily of hydrogen, carbon dioxide, methane, carbon monoxide and other light hydrocarbons. The liquid products contained high levels of organic matter, ammonia nitrogen and a few heavy metals. Compared with the landfilling of sewage sludge, the solid residues were in accordance with the Chinese standard for sludge quality in co-landfilling even without further treatment. In addition, the heavy metals in solid products exhibited more stable characteristics attributable to the reduced leaching toxicity after supercritical water gasification. PMID:22856292

  12. Glucose and fructose decomposition in subcritical and supercritical water: Detailed reaction pathway, mechanisms, and kinetics

    SciTech Connect

    Kabyemela, B.M.; Adschiri, T.; Malaluan, R.M.; Arai, K.

    1999-08-01

    The authors are developing a new catalyst-free process of cellulose decomposition in supercritical water. In their initial study on the cellulose decomposition in supercritical water, the main products of cellulose decomposition were found to be oligomers of glucose (cellobiose, cellotriose, etc.) and glucose at short residence times (400 C, 25 MPa, 0.05 s). The kinetics of glucose at these conditions can be useful in understanding the reaction pathways of cellulose. Experiments were performed on the products of glucose decomposition at short residence times to elucidate the reaction pathways and evaluate kinetics of glucose and fructose decomposition in sub- and supercritical water. The conditions were a temperature of 300--400 C and pressure of 25--40 MPa for extremely short residence times between 0.02 and 2 s. The products of glucose decomposition were fructose, a product of isomerization, 1,6-anhydroglucose, a product of dehydration, and erythrose and glyceraldehyde, products of C-C bond cleavage. Fructose underwent reactions similar to glucose except that it did not form 1,6-anhydroglucose and isomerization to glucose is negligible. The mechanism for the products formed from C-C bond cleavage could be explained by reverse aldol condensation and the double-bond rule of the respective enediols formed during the Lobry de Bruyn Alberda van Ekenstein transformation. The differential equations resulting from the proposed pathways were fit to experimental results to obtain the kinetic rate constants.

  13. On the local environment surrounding pyrene in near- and supercritical water

    SciTech Connect

    Niemeyer, E.D.; Dunbar, R.A.; Bright, F.V.

    1997-10-01

    We use steady-state and time-resolved fluorescence spectroscopy to probe local solvent{endash}solute interactions between pyrene (the solute) and supercritical water (SCW). Toward this end, we have developed a new fiber-optic-based titanium high-pressure optical cell which can withstand the temperatures and pressure needed to generate supercritical water. Static fluorescence measurements indicate that there is an increase in the local water density surrounding the pyrene molecules (clustering) up to five times the bulk fluid density. This extent of clustering is most prevalent at about one-half the critical density. Consistent with previous work on more mild supercritical fluids (e.g., CO{sub 2}, CF{sub 3}H, C{sub 2}H{sub 6}), the extent of this solute-fluid clustering decreases as the system temperature and pressure are increased. Time-resolved fluorescence measurements show that the excited-state decay kinetics are exponentially activated and not themselves affected by this solute-fluid clustering process. {copyright} {ital 1997} {ital Society for Applied Spectroscopy}

  14. Supercritical fluid extraction and organic solvent microextraction of chemical agent simulants from soil

    SciTech Connect

    Griest, W.H.; Ramsey, R.S.; Ho, C.h.; Caldwell, W.M.

    1991-12-31

    Experiments with chemical warfare agent simulants suggest that supercritical fluid extraction can achieve good extraction recoveries of agents in soil and produce less laboratory waste than current organic solvent extraction methods. Two-ppm spikes in 1 g of Rocky Mountain Arsenal Standard Soil were extracted using 5% methanol in carbon dioxide at 300 atm for 2 min at 60{degrees}C. Recoveries (n=3) were 79{plus_minus}23% for dimethylmethylphosphonate, 93{plus_minus}14% for 2-chlorethylethylsulfide, 92{plus_minus}13% for diisopropylfluorophosphate, and 95{plus_minus}17% for diisopropylmethylphosphonate. A 5 min ultrasonic micro-scale extraction using methanol is more reproducible but less efficient.

  15. Supercritical fluid extraction and organic solvent microextraction of chemical agent simulants from soil

    SciTech Connect

    Griest, W.H.; Ramsey, R.S.; Ho, C.h.; Caldwell, W.M.

    1991-01-01

    Experiments with chemical warfare agent simulants suggest that supercritical fluid extraction can achieve good extraction recoveries of agents in soil and produce less laboratory waste than current organic solvent extraction methods. Two-ppm spikes in 1 g of Rocky Mountain Arsenal Standard Soil were extracted using 5% methanol in carbon dioxide at 300 atm for 2 min at 60{degrees}C. Recoveries (n=3) were 79{plus minus}23% for dimethylmethylphosphonate, 93{plus minus}14% for 2-chlorethylethylsulfide, 92{plus minus}13% for diisopropylfluorophosphate, and 95{plus minus}17% for diisopropylmethylphosphonate. A 5 min ultrasonic micro-scale extraction using methanol is more reproducible but less efficient.

  16. Two-dimensional numerical simulations of supercritical accretion flows revisited

    SciTech Connect

    Yang, Xiao-Hong; Yuan, Feng; Bu, De-Fu; Ohsuga, Ken E-mail: fyuan@shao.ac.cn

    2014-01-01

    We study the dynamics of super-Eddington accretion flows by performing two-dimensional radiation-hydrodynamic simulations. Compared with previous works, in this paper we include the T {sub θφ} component of the viscous stress and consider various values of the viscous parameter α. We find that when T {sub θφ} is included, the rotational speed of the high-latitude flow decreases, while the density increases and decreases at the high and low latitudes, respectively. We calculate the radial profiles of inflow and outflow rates. We find that the inflow rate decreases inward, following a power law form of M-dot {sub in}∝r{sup s}. The value of s depends on the magnitude of α and is within the range of ∼0.4-1.0. Correspondingly, the radial profile of density becomes flatter compared with the case of a constant M-dot (r). We find that the density profile can be described by ρ(r)∝r {sup –p} and the value of p is almost same for a wide range of α ranging from α = 0.1 to 0.005. The inward decrease of inflow accretion rate is very similar to hot accretion flows, which is attributed to the mass loss in outflows. To study the origin of outflow, we analyze the convective stability of the slim disk. We find that depending on the value of α, the flow is marginally stable (when α is small) or unstable (when α is large). This is different from the case of hydrodynamical hot accretion flow, where radiation is dynamically unimportant and the flow is always convectively unstable. We speculate that the reason for the difference is because radiation can stabilize convection. The origin of outflow is thus likely because of the joint function of convection and radiation, but further investigation is required.

  17. Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube

    SciTech Connect

    Bae, Y. Y.; Hong, S. D.; Kim, Y. W.

    2012-07-01

    A number of computational works have been performed so far for the simulation of heat transfer in a supercritical fluid. The simulations, however, faced a lot of difficulties when heat transfer deteriorates due either to buoyancy or by acceleration. When the bulk temperature approaches the pseudo-critical temperature the fluid experiences a severe axial density gradient on top of a severe radial one. Earlier numerical calculations showed, without exception, unrealistic over-predictions, as soon as the bulk temperature exceeded the pseudo-critical temperature. The over-predictions might have been resulted from an inapplicability of widely-used turbulence models. One of the major causes for the difficulties may probably be an assumption of a constant turbulent Prandtl number. Recent research, both numerical and experimental, indicates that the turbulent Prandtl number is never a constant when the gradient of physical properties is significant. This paper describes the applicability of a variable turbulent Prandtl number to the numerical simulation of heat transfer in supercritical fluids flowing in narrow vertical tubes. (authors)

  18. Design and technology development of solid breeder blanket cooled by supercritical water in Japan

    NASA Astrophysics Data System (ADS)

    Enoeda, M.; Kosaku, Y.; Hatano, T.; Kuroda, T.; Miki, N.; Honma, T.; Akiba, M.; Konishi, S.; Nakamura, H.; Kawamura, Y.; Sato, S.; Furuya, K.; Asaoka, Y.; Okano, K.

    2003-12-01

    This paper presents results of conceptual design activities and associated R&D of a solid breeder blanket system for demonstration of power generation fusion reactors (DEMO blanket) cooled by supercritical water. The Fusion Council of Japan developed the long-term research and development programme of the blanket in 1999. To make the fusion DEMO reactor more attractive, a higher thermal efficiency of more than 40% was strongly recommended. To meet this requirement, the design of the DEMO fusion reactor was carried out. In conjunction with the reactor design, a new concept of a solid breeder blanket cooled by supercritical water was proposed and design and technology development of a solid breeder blanket cooled by supercritical water was performed. By thermo-mechanical analyses of the first wall, the tresca stress was evaluated to be 428 MPa, which clears the 3Sm value of F82H. By thermal and nuclear analyses of the breeder layers, it was shown that a net TBR of more than 1.05 can be achieved. By thermal analysis of the supercritical water power plant, it was shown that a thermal efficiency of more than 41% is achievable. The design work included design of the coolant flow pattern for blanket modules, module structure design, thermo-mechanical analysis and neutronics analysis of the blanket module, and analyses of the tritium inventory and permeation. Preliminary integration of the design of a solid breeder blanket cooled by supercritical water was achieved in this study. In parallel with the design activities, engineering R&D was conducted covering all necessary issues, such as development of structural materials, tritium breeding materials, and neutron multiplier materials; neutronics experiments and analyses; and development of the blanket module fabrication technology. Upon developing the fabrication technology for the first wall and box structure, a hot isostatic pressing bonded F82H first wall mock-up with embedded rectangular cooling channels was

  19. Stability analysis of a square rod bundle sub-channel in supercritical water reactor

    NASA Astrophysics Data System (ADS)

    Hai-jun, Wang; Ting, You; Lei, Zhang; Hong-fang, Gu; Yu-shan, Luo; Ji-lian, Bian

    2013-07-01

    Extensive investigations on the flow and heat transfer behavior in SCWR fuel assembly have been undertaken worldwide. However, stability analysis of supercritical water in the sub-channels of tight lattices is still lacking. In this paper, the flow stability of a fuel bundle channel with square pitches has been analyzed using commercial CFD code-ANSYS Fluent. Typical dynamic instability of Density Wave Oscillation (DWO) has occurred in heated channel containing fluids at supercritical pressure. A further discussion about the impacts of various operational parameters (e.g. power input, system pressure, mass velocity, inlet temperature, etc) shows that the system becomes more stable as system pressure and/or mass flow rate increases. An increase in inlet temperature also has a stabilizing effect on the system.

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

    PubMed

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

    2014-08-01

    The scarce data concerning the gasification of carbonaceous solids with supercritical water (SCW) suggest the great potential of this method to produce a valuable green fuel such as H2. However, the extraordinary properties of SCW have not been properly applied to H2 production because the mechanism that governs gasification under these conditions remains unclear. Here, we present a study in which this reaction is explored within the largest pressure range ever assayed in this field, from 1 to 1000 bar. The amplitude of the experimental conditions investigated highlights the various pathways that govern gasification with steam and SCW. Under supercritical conditions, the clusters formed around the superficial groups of the solid reduce the energetic requirements for gasification and generate CO2 as a primary product of the reaction. Consequently, gasification with SCW is significantly faster than that using steam, and the produced gases are richer and more appropriate to obtain pure H2. PMID:26277952

  1. Meeting Vision 21 goals with supercritical water gasification (SCWG) of biomass/coal slurries

    SciTech Connect

    Tolman, R.; Spritzer, M.; Hong, G.T.; Rickman, B.; Parkinson, W.J.

    2000-07-01

    In the Vapor Transmission Cycle (VTC), a special condensing expander turbine is planned to reduce temperature and pressure for low-temperature cleaning and to maintain quality and combustibility of the fuel vapor for a modern gas turbine. The VTC generates clean fuel gas and steam for gas turbines by feeding water slurries or emulsions above about 25% solids, including coal fines, coal water fuels, biomass, composted municipal refuse, sewage sludge, crumb rubber and pulp and paper wastes in patented HRSG tubes. A commercial method of particle scrubbing is used to improve heat transfer and prevent corrosion and deposition on heat transfer surfaces. Tests were conducted to produce clean fuels for gas turbines and fuel cells via supercritical water gasification (SCWG). The study includes lab-scale testing of composted packer truck refuse and sewage sludge made in an aerobic digester without shredding. A computer-based process simulation model has been prepared that includes material and energy balances that simulate commercial-scale operations of the VTC. Funded by DOE, pilot-scale data produced by General Atomics for sewage sludge shows that SCWG above 640 C and low residence time without an oxidizer can produce a gaseous mixture containing over 25 vol. % hydrogen in methane, carbon monoxide, carbon dioxide and higher light hydrocarbons. Excess hydrogen can be separated for use in fuel cells. Carbon can be separated up to the amount of fixed carbon in the proximate analysis of the solids in the feed. This carbon can be burned in an existing combustion system to help provide the heat required for SCWG, or it can be used to remove pollutants and hydrocarbons from water and air. Test and modeling results will be presented. Preliminary life cycle costs analyses will be presented that establish MSW and sludge disposal fees that improve operating economics over higher-cost fuels. Analyses show that the cost and schedule advantages of natural gas-fired combined cycle

  2. Effects of water on biodiesel fuel production by supercritical methanol treatment.

    PubMed

    Kusdiana, Dadan; Saka, Shiro

    2004-02-01

    In the conventional transesterification of fats/vegetable oils for biodiesel production, free fatty acids and water always produce negative effects, since the presence of free fatty acids and water causes soap formation, consumes catalyst and reduces catalyst effectiveness, all of which result in a low conversion. The objective of this study was, therefore, to investigate the effect of water on the yield of methyl esters in transesterification of triglycerides and methyl esterification of fatty acids as treated by catalyst-free supercritical methanol. The presence of water did not have a significant effect on the yield, as complete conversions were always achieved regardless of the content of water. In fact, the present of water at a certain amount could enhance the methyl esters formation. For the vegetable oil containing water, three types of reaction took place; transesterification and hydrolysis of triglycerides and methyl esterification of fatty acids proceeded simultaneously during the treatment to produce a high yield. These results were compared with those of methyl esters prepared by acid- and alkaline-catalyzed methods. The finding demonstrated that, by a supercritical methanol approach, crude vegetable oil as well as its wastes could be readily used for biodiesel fuel production in a simple preparation. PMID:14607489

  3. Large-eddy simulation of nitrogen injection at trans- and supercritical conditions

    NASA Astrophysics Data System (ADS)

    Müller, Hagen; Niedermeier, Christoph A.; Matheis, Jan; Pfitzner, Michael; Hickel, Stefan

    2016-01-01

    Large-eddy simulations (LESs) of cryogenic nitrogen injection into a warm environment at supercritical pressure are performed and real-gas thermodynamics models and subgrid-scale (SGS) turbulence models are evaluated. The comparison of different SGS models — the Smagorinsky model, the Vreman model, and the adaptive local deconvolution method — shows that the representation of turbulence on the resolved scales has a notable effect on the location of jet break-up, whereas the particular modeling of unresolved scales is less important for the overall mean flow field evolution. More important are the models for the fluid's thermodynamic state. The injected fluid is either in a supercritical or in a transcritical state and undergoes a pseudo-boiling process during mixing. Such flows typically exhibit strong density gradients that delay the instability growth and can lead to a redistribution of turbulence kinetic energy from the radial to the axial flow direction. We evaluate novel volume-translation methods on the basis of the cubic Peng-Robinson equation of state in the framework of LES. At small extra computational cost, their application considerably improves the simulation results compared to the standard formulation. Furthermore, we found that the choice of inflow temperature is crucial for the reproduction of the experimental results and that heat addition within the injector can affect the mean flow field in comparison to results with an adiabatic injector.

  4. Dynamics of supercritical methanol of varying density from first principles simulations: Hydrogen bond fluctuations, vibrational spectral diffusion, and orientational relaxation

    NASA Astrophysics Data System (ADS)

    Yadav, Vivek Kumar; Chandra, Amalendu

    2013-06-01

    A first principles study of the dynamics of supercritical methanol is carried out by means of ab initio molecular dynamics simulations. In particular, the fluctuation dynamics of hydroxyl stretch frequencies, hydrogen bonds, dangling hydroxyl groups, and orientation of methanol molecules are investigated for three different densities at 523 K. Apart from the dynamical properties, various equilibrium properties of supercritical methanol such as the local density distributions and structural correlations, hydrogen bonding aspects, frequency-structure correlations, and dipole distributions of methanol molecules are also investigated. In addition to the density dependence of various equilibrium and dynamical properties, their dependencies on dispersion interactions are also studied by carrying out additional simulations using a dispersion corrected density functional for all the systems. It is found that the hydrogen bonding between methanol molecules decreases significantly as we move to the supercritical state from the ambient one. The inclusion of dispersion interactions is found to increase the number of hydrogen bonds to some extent. Calculations of the frequency-structure correlation coefficient reveal that a statistical correlation between the hydroxyl stretch frequency and the nearest hydrogen-oxygen distance continues to exist even at supercritical states of methanol, although it is weakened with increase of temperature and decrease of density. In the supercritical state, the frequency time correlation function is found to decay with two time scales: One around or less than 100 fs and the other in the region of 250-700 fs. It is found that, for supercritical methanol, the times scales of vibrational spectral diffusion are determined by an interplay between the dynamics of hydrogen bonds, dangling OD groups, and inertial rotation of methanol molecules and the roles of these various components are found to vary with density of the supercritical solvent. Effects

  5. RELAP5-3D Code for Supercritical-Pressure Light-Water-Cooled Reactors

    SciTech Connect

    Riemke, Richard Allan; Davis, Cliff Bybee; Schultz, Richard Raphael

    2003-04-01

    The RELAP5-3D computer program has been improved for analysis of supercritical-pressure, light-water-cooled reactors. Several code modifications were implemented to correct code execution failures. Changes were made to the steam table generation, steam table interpolation, metastable states, interfacial heat transfer coefficients, and transport properties (viscosity and thermal conductivity). The code modifications now allow the code to run slow transients above the critical pressure as well as blowdown transients (modified Edwards pipe and modified existing pressurized water reactor model) that pass near the critical point.

  6. Interdroplet attractive forces in AOT water-in-oil microemulsions formed in subcritical and supercritical solvents

    SciTech Connect

    Tingey, J.M.; Fulton, J.L.; Smith, R.D. )

    1990-03-08

    The van der Waals attractive interactions between aqueous droplets in water-in-oil type microemulsions have been investigated for a range of continuous-phase solvents including the alkanes from methane to isooctane and the noble gases, krypton and xenon. Hamaker constants for water droplets with surfactant shells of the sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in subcritical and supercritical solvents were calculated by using Lifshitz theory and the resulting interaction potential calculations qualitatively account for many features of the phase behavior of these systems.

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

    PubMed

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

    2012-11-01

    This paper presents bio-oil preparation by direct liquefaction of Dunaliella tertiolecta (D. tertiolecta) with sub/supercritical ethanol-water as the medium in a batch autoclave with high temperature and high pressure. The results indicated that ethanol and water showed synergistic effects on direct liquefaction of D. tertiolecta. The maximum bio-oil yield was 64.68%, with an optimal D. tertiolecta conversion of 98.24% in sub/supercritical ethanol-water. The detailed chemical compositional analysis of the bio-oil was performed using an EA, FT-IR, and GC-MS. The empirical formulas of the bio-oil obtained using the ethanol-water co-solvent (40%, v/v) and sole water as the reaction medium were CH(1.52)O(0.14)N(0.06) and CH(1.43)O(0.23)N(0.09), with calorific values of 34.96 and 29.80 MJ kg(-1), respectively. XPS and SEM results showed that ethanol-water is a very effective reaction medium in the liquefaction. A plausible reaction mechanism of the main chemical component in D. tertiolecta is proposed based on our results and the literatures. PMID:22989646

  8. Oxidation of phenolics in supercritical water. Quarterly technical progress report, March 1, 1994--May 31, 1994

    SciTech Connect

    Savage, P.E.

    1994-09-01

    An environmental hazard associated with coal liquefaction and gasification is the generation of aqueous waste streams containing phenolics and carcinogenic organics such as polynuclear aromatics. Oxidation in supercritical water (SCW) is an emerging technology for the ultimate destruction of phenolics and other organics in waste water streams. SCW oxidation involves the oxidation of organics in an aqueous medium at temperatures between 400-650{degrees}C and pressures around 250 atm. These conditions exceed the thermodynamic critical point of water, hence the water is said to be supercritical. Wastes can be converted by SCWO to benign products: carbon is converted to CO{sub 2}, hydrogen to H{sub 2}O, and nitrogen to N{sub 2} or N{sub 2}O (but not NO{sub X}). SCWO possesses several attractive features. (1) The effluents from the SCWO process can be collected or held in a recycle loop so the process can be easily {open_quotes}bottled up{close_quotes} with no uncontrolled emissions should an upset occur. (2) The oxidation reaction is exothermic, so it is possible to operate the SCWO reactor in an autothermal mode. That is, the oxidation of the organic material in the aqueous stream liberates sufficient heat to maintain the elevated reactor temperature and also preheat the feed. Thus, after start-up, the process would not require an external energy source and could even be used to produce energy provided the organics content in the feed stream was sufficiently high. (3) Operating at supercritical conditions also provides a single, homogeneous fluid phase in the reactor. Indeed, water above its critical point has a high solubility for organics, and it is totally miscible with oxygen. (4) The temperature in SCWO is high enough to provide rapid reaction rates but not so high that alloys begin to lose their mechanical strength. Thus, the oxidation of organics goes essentially to completion in a very short time (a few seconds).

  9. Kinetics of glucose epimerization and decomposition in subcritical and supercritical water

    SciTech Connect

    Kabyemela, B.M.; Adschiri, Tadafumi; Malaluan, R.M.; Arai, Kunio

    1997-05-01

    Glucose decomposition kinetics in subcritical and supercritical water were studied for the temperatures 573, 623, and 673 K, pressures between 25 and 40 MPa, and residence times between 0.02 and 2 s. Glucose decomposition products were fructose, saccharinic acids, erythrose, glyceraldehyde, 1,6-anhydroglucose, dihydroxyacetone, pyruvaldehyde, and small amounts of 5-hydroxymethylfurfural. Fructose was also studied and found to decompose to products similar to those of glucose, except that its epimerization to glucose was negligibly low and no formation of 1,6-anhydroglucose was detected. The authors concluded that only the forward epimerization of glucose to fructose was important. The glucose decomposition pathway could be described in terms of a forward epimerization rate, r{sub gf}, a fructose to decomposition products rate, r{sub f}, and a glucose to decomposition products rate, r{sub g}. A kinetic model based on this pathway gave good correlation of the experimental data. In the subcritical region, r{sub g}, r{sub f}, and r{sub gf} showed only small changes with pressure at a given temperature. In the supercritical region, the rate of glucose decomposition decreased with pressure at a given temperature. The reason for this decrease was mainly due to the decrease in r{sub gf}. The pressure effect in the supercritical region shows that there is a shift among the kinetic rates, which can lead to higher selectivity for glucose when decomposing cellulosic materials.

  10. Hydrolysis of vegetable oils in sub- and supercritical water

    SciTech Connect

    Holliday, R.L.; King, J.W.; List, G.R.

    1997-03-01

    Water, in its subcritical state, can be used as both a solvent and reactant for the hydrolysis of triglycerides. In this study, soybean, linseed, and coconut oils were successfully and reproducibly hydrolyzed to free fatty acids with water at a density of 0.7 g/mL and temperatures of 260--280 C. Under these conditions the reaction proceeds quickly, with conversion of greater than 97% after 15--20 min. Some geometric isomerization of the linolenic acids was observed at reaction temperatures as low as 250 C. Reactions carried out at higher temperatures and pressures, up to the critical point of water, produced either/or degradation, pyrolysis, and polymerization, of the oils and resultant fatty acids.

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

    NASA Astrophysics Data System (ADS)

    Knight, Chase C.

    complete recycling loop. After showing the feasibility and power of this technology, the third phase of the study was focused on the fundamentals on the degradation of highly cross-linked polymer network by sub- and near-critical water. A methodology framework was established to study the apparent kinetics of the degradation of epoxy in sub-critical water. The reaction rate was modeled by a phenomenological rate model of nth order, and the rate constant was modeled by taking into account of the contributions of important physical parameters, e.g., pressure, temperature and dielectric constants. The applicability of the established model to describe the degradation kinetics was confirmed by the validation runs. This model is a suitable starting point to gain the knowledge required for eventual industrial process design. The final phase of this research consisted of a preliminary foray into investigating the economic feasibility of this technology. A process model was designed around a reactor which was sized according to considerations of industrial relevancy. The simulation of the process was done using Aspen Plus, powerful and comprehensive process simulation software. Economic analysis of this pseudo-realistic process suggested that such technology was economically viable and competitive comparing to other recycling technologies. In summary, this dissertation work represents the first comprehensive investigation on recycling aerospace-grade, multilayer woven fabric composites using supercritical and sub-critical water. The fundamental knowledge gained and process technology developed during this research is anticipated to play an important role in advancing this recycling technology toward potential adoption and implementation by the recycling and composite industry.

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

    SciTech Connect

    Savage, P.E.

    1996-11-01

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

  13. Burst wait time simulation of CALIBAN reactor at delayed super-critical state

    SciTech Connect

    Humbert, P.; Authier, N.; Richard, B.; Grivot, P.; Casoli, P.

    2012-07-01

    In the past, the super prompt critical wait time probability distribution was measured on CALIBAN fast burst reactor [4]. Afterwards, these experiments were simulated with a very good agreement by solving the non-extinction probability equation [5]. Recently, the burst wait time probability distribution has been measured at CEA-Valduc on CALIBAN at different delayed super-critical states [6]. However, in the delayed super-critical case the non-extinction probability does not give access to the wait time distribution. In this case it is necessary to compute the time dependent evolution of the full neutron count number probability distribution. In this paper we present the point model deterministic method used to calculate the probability distribution of the wait time before a prescribed count level taking into account prompt neutrons and delayed neutron precursors. This method is based on the solution of the time dependent adjoint Kolmogorov master equations for the number of detections using the generating function methodology [8,9,10] and inverse discrete Fourier transforms. The obtained results are then compared to the measurements and Monte-Carlo calculations based on the algorithm presented in [7]. (authors)

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

    PubMed

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

    2013-08-01

    Polyvinyl alcohol is a refractory compound widely used in industry. Here we report supercritical water oxidation of polyvinyl alcohol solution and desizing wastewater with and without sodium hydroxide addition. However, it is difficult to implement complete degradation of organics even though polyvinyl alcohol can readily crack under supercritical water treatment. Sodium hydroxide had a significant catalytic effect during the supercritical water oxidation of polyvinyl alcohol. It appears that the OH- ion participated in the C-C bond cleavage of polyvinyl alcohol molecules, the CO2-capture reaction and the neutralization of intermediate organic acids, promoting the overall reactions moving in the forward direction. Acetaldehyde was a typical intermediate product during reaction. For supercritical water oxidation of desizing wastewater, a high destruction rate (98.25%) based on total organic carbon was achieved. In addition, cases where initial wastewater was alkaline were favorable for supercritical water oxidation treatment, but salt precipitation and blockage issues arising during the process need to be taken into account seriously. PMID:24520696

  15. Evaluation of pretreatment processes for supercritical water oxidation

    SciTech Connect

    Barnes, C.M.

    1994-01-01

    This report evaluates processes to chemically treat US Department of Energy wastes to remove organic halogens, phosphorus, and sulfur. Chemical equilibrium calculations, process simulations, and responses from developers and licensors form the basis for comparisons. Gas-phase catalytic hydrogenation processes, strong base and base catalyzed processes, high pressure hydrolysis, and other emerging or commercial dehalogenation processes (both liquid and mixed phase) were considered. Cost estimates for full-scale processes and demonstration testing are given. Based on the evaluation, testing of a hydrogenation process and a strong base process are recommended.

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

    SciTech Connect

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

    2002-01-01

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

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

    SciTech Connect

    Antal, M.J. Jr.; Adschiri, T.; Ekbom, T.

    1996-10-01

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

  18. Water Reactivity in the Liquid and Supercritical CO2 Phase: Has Half the Story Been Neglected?

    SciTech Connect

    McGrail, B. Peter; Schaef, Herbert T.; Glezakou, Vassiliki Alexandra; Dang, Liem X.; Owen, Antionette T.

    2009-02-01

    Aqueous-phase mediated chemical reactions with dissolved CO2 have long been considered the principal if not only reactive process supporting mineralization reactions with basalt and other reactive reservoir rocks and caprocks in deep geologic sequestration systems. This is not surprising given the quite high solubility of CO2 in the aqueous phase and ample evidence from natural systems of the reactivity of CO2-charged waters with a variety of silicate minerals. In contrast, comparatively scant attention has been directed at reactivity of water solvated in liquid and supercritical CO2, with the exception of interest in the impacts of water in CO2 on the corrosion of pipeline steels. The results presented in this paper show that the most interesting and important aspects of water reactivity with metal and oxide surfaces of interest in geologic sequestration systems actually occurs in the liquid or supercritical CO2 phase. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  19. Supercritical water oxidation technology for DWPF. [Defense Waste Processing Facility (DWPF)

    SciTech Connect

    Carter, J.T.; Gentilucci, J.A.

    1992-02-07

    At the request of Mr. H.L. Brandt and others in the Savannah River Field Office High Level Waste Division office, DWPF, and SRL personnel have reviewed two potential applications for supercritical water oxidation technology in DWPF. The first application would replace the current hydrolysis process by destroying the organic fractions of the precipitated cesium / potassium tetraphenylborate slurry. The second application pertains to liquid benzene destruction. After a thorough evaluation the first application is not recommended. The second is ready to be tested if needed.

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

    SciTech Connect

    Buelow, S.J.; Allen, D.; Anderson, G.K.

    1995-04-03

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

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

    SciTech Connect

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

    2005-10-01

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

  2. Superior Corrosion Resistance Properties of TiN-Based Coatings on Zircaloy Tubes in Supercritical Water

    SciTech Connect

    Fauzia Khatkhatay; Liang Jiao; Jie Jian; Zhijie Jiao; Hongbin Zhang; Jian Gan; Haiyan Wang; Wenrui Zhang; Xinghang Zhang

    2014-08-01

    Thin films of TiN and Ti0.35Al0.65N nanocomposite were deposited on polished Zircaloy-4 tubes. After exposure to supercritical water for 48 h, the coated tubes are remarkably intact, while the bare uncoated tube shows severe oxidation and breakaway corrosion. X-ray diffraction patterns, secondary electron images, backscattered electron images, and energy dispersive X-ray spectroscopy data from the tube surfaces and cross-sections show that a protective oxide, formed on the film surface, effectively prevents further oxidation and corrosion to the Zircaloy-4 tubes. This result demonstrates the effectiveness of thin film ceramics as protective coatings under extreme environments.

  3. Kinetics of the catalytic oxidation of phenol over manganese oxide in supercritical water

    SciTech Connect

    Oshima, Yoshito; Tomita, Kengo; Koda, Seiichiro

    1999-11-01

    A kinetic analysis was made for the phenol disappearance rate in catalytic oxidation of phenol over MnO{sub 2} in supercritical water at a fixed temperature of 425 C and pressures between 22.7 and 27.2 MPa. The nonsupported MnO{sub 2} catalyst possessed a strong activity for promoting phenol oxidation, though the overall reaction rate was appreciably influenced by internal mass-transfer resistance. From the kinetic analysis on the reaction rate of the phenol disappearance, the global rate expression of the surface reaction was obtained, where the reaction orders with respect to phenol, oxygen, and water were almost unity, 0.7, and {minus}2.0, respectively. A Langmuir-type mechanism, in which phenol and oxygen adsorbed on the catalytic sites and water adsorbed on the same site to inhibit the phenol and oxygen adsorption, was proposed to explain the reaction orders for phenol, oxygen, and water.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. Catalytic oxidation of phenol over MnO{sub 2} in supercritical water

    SciTech Connect

    Yu, J.; Savage, P.E.

    1999-10-01

    Bulk MnO{sub 2} was used as a catalyst for phenol oxidation in supercritical water at 380--420 C and 219--300 atm in a flow reactor. The bulk MnO{sub 2} catalyst enhances both the phenol disappearance and CO{sub 2} formation rates during supercritical water oxidation (SCWO), but it does not affect the selectivity to CO{sub 2} or to the phenol dimers at a given phenol conversion. The role of the catalyst appears to be accelerating the rate of formation of phenoxy radicals, which then react in the fluid phase by the same mechanism operative for noncatalytic SCWO of phenol. The rates of phenol disappearance and CO{sub 2} formation are sensitive to the phenol and O{sub 2} concentrations but independent of the water density. Both power-law and dual site Langmuir-Hinshelwood-Hougen-Watson (LHHW) rate laws were developed to correlate the catalytic kinetics. Results show that SCWO reactor volumes can be reduced by an order of magnitude if bulk MnO{sub 2} is used as the catalyst and by yet another order of magnitude if a supported oxidation catalyst is used.

  6. Preliminary corrosion studies of candidate materials for supercritical water oxidation reactor systems. Master's thesis

    SciTech Connect

    Orzalli, J.C.

    1994-05-01

    An experimental test facility has been designed and constructed for investigation of the corrosion behavior of candidate materials in a supercritical water oxidation environment. The high temperatures (500 deg C) and high pressures (300 atm) required in this process, made the experimental apparatus construction and control a complex engineering problem. The facility consists of two systems. The first is an exposure autoclave internal volume 850 ml, with associated monitoring and control systems for conducting long term exposure testing of test coupons and U-bends. The second is an electrochemical cell with a potentiostat and frequency response analyzer for conducting Electronic Impedance Spectroscopy (EIS) in the supercritical water environment. Exposure testing of three candidate materials; Inconel 625, Hastelloy C-276 and 316 stainless steel was conducted at three temperature regimes corresponding to three locations in a SCWO waste treatment system. Preliminary results are presented in an environment of demineralized water as a control. Experimental results indicate evidence of a film on the materials characterized by slight weight gain. Light and confocal laser light microscopic evaluations revealed the presence of localized pitting corrosion on the Inconel 625.

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

    PubMed

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

    2016-09-01

    The supercritical water oxidation reaction of quinazoline and a set of related reaction products were investigated in batch reactors by varying the temperature (T, 400-600 °C), time (t, 0-400 s), water density (ρ, 70.79-166.28  kg m(-3)) and oxidation coefficient (OC, 0-4.0). The TOC removal efficiency (CRE) increased significantly as the OC increased, whereas this effect was very limited at high OC (>2.0). Lack of oxygen resulted in low CRE and TN removal efficiency (NRE), also cause coke-formation, and giving high yield of NH3 and nitrogenous organic intermediates. Prolonging reaction time did not provide an appreciable improvement on CRE but remarkably increased NRE at temperature higher than 500 °C. Pyrimidines and pyridines as the nitrogenous intermediates were largely found in GC-MS spectrum. Polymerization among benzene, phenyl radical and benzyl radical played important roles in the formation of PAHs, such as naphthalene, biphenyl, phenanthrene. These collective results showed how the yield of intermediate products responded to changes in the process variables, which permitted the development of a potential reaction network for supercritical water oxidation of quinazoline. PMID:27179598

  8. IAEA coordinated research project on thermal-hydraulics of Supercritical Water-Cooled Reactors (SCWRs)

    SciTech Connect

    Yamada, K.; Aksan, S. N.

    2012-07-01

    The Supercritical Water-Cooled Reactor (SCWR) is an innovative water-cooled reactor concept, which uses supercritical pressure water as reactor coolant. It has been attracting interest of many researchers in various countries mainly due to its benefits of high thermal efficiency and simple primary systems, resulting in low capital cost. The IAEA started in 2008 a Coordinated Research Project (CRP) on Thermal-Hydraulics of SCWRs as a forum to foster the exchange of technical information and international collaboration in research and development. This paper summarizes the activities and current status of the CRP, as well as major progress achieved to date. At present, 15 institutions closely collaborate in several tasks. Some organizations have been conducting thermal-hydraulics experiments and analysing the data, and others have been participating in code-to-test and/or code-to-code benchmark exercises. The expected outputs of the CRP are also discussed. Finally, the paper introduces several IAEA activities relating to or arising from the CRP. (authors)

  9. Molecular simulation of CO chemisorption on Co(0001) in presence of supercritical fluid solvent: A potential of mean force study.

    PubMed

    Asiaee, Alireza; Benjamin, Kenneth M

    2016-08-28

    For several decades, heterogeneous catalytic processes have been improved through utilizing supercritical fluids (SCFs) as solvents. While numerous experimental studies have been established across a range of chemistries, such as oxidation, pyrolysis, amination, and Fischer-Tropsch synthesis, still there is little fundamental, molecular-level information regarding the role of the SCF on elementary heterogeneous catalytic steps. In this study, the influence of hexane solvent on the adsorption of carbon monoxide on Co(0001), as the first step in the reaction mechanism of many processes involving syngas conversion, is probed. Simulations are performed at various bulk hexane densities, ranging from ideal gas conditions (no SCF hexane) to various near- and super-critical hexane densities. For this purpose, both density functional theory and molecular dynamics simulations are employed to determine the adsorption energy and free energy change during CO chemisorption. Potential of mean force calculations, utilizing umbrella sampling and the weighted histogram analysis method, provide the first commentary on SCF solvent effects on the energetic aspects of the chemisorption process. Simulation results indicate an enhanced stability of CO adsorption on the catalyst surface in the presence of supercritical hexane within the reduced pressure range of 1.0-1.5 at a constant temperature of 523 K. Furthermore, it is shown that the maximum stability of CO in the adsorbed state as a function of supercritical hexane density at 523 K nearly coincides with the maximum isothermal compressibility of bulk hexane at this temperature. PMID:27586934

  10. Applications of supercritical fluids.

    PubMed

    Brunner, Gerd

    2010-01-01

    This review discusses supercritical fluids in industrial and near-to-industry applications. Supercritical fluids are flexible tools for processing materials. Supercritical fluids have been applied to mass-transfer processes, phase-transition processes, reactive systems, materials-related processes, and nanostructured materials. Some applications are already at industrial capacity, whereas others remain under development. In addition to extraction, application areas include impregnation and cleaning, multistage countercurrent separation, particle formation, coating, and reactive systems such as hydrogenation, biomass gasification, and supercritical water oxidation. Polymers are modified with supercritical fluids, and colloids and emulsions as well as nanostructured materials exhibit interesting phenomena when in contact with supercritical fluids that can be industrially exploited. For these applications to succeed, the properties of supercritical fluids in combination with the materials processed must be clearly determined and fundamental knowledge of the complex behavior must be made readily available. PMID:22432584

  11. Status on R and D Planning for Supercritical Water Cooled Reactor Systems in the 6. European Framework Programme

    SciTech Connect

    Starflinger, J.; Schulenberg, T.; Aksan, N.; Bittermann, D.; Heikinheimo, L.; Rimpault, G.

    2004-07-01

    On July 30, 2003, EURATOM signed the charter to join the Generation IV International Forum and thus to contribute to innovative reactor design and development. Among other concepts, supercritical water cooled reactor systems shall be foreseen as their contribution. In order to support this international forum, a dedicated budget for R and D of innovative concepts is planned for the 6. European Framework Programme of the European Commission. Currently, a detailed work plan for supercritical water cooled reactor systems is being worked out, in order to be presented and decided by the European Commission thereafter. It shall include: - Design studies of a thermal reactor core, its reactor pressure vessel internals and of the balance of plant. - Study of a fast reactor option for sustainable use of fuel and for Plutonium management. - Study of the corrosion behavior and other performances of candidate materials at supercritical pressures. - Detailed investigations of heat transfer and pressure drop at supercritical pressures and at part load operation conditions of the reactor. - Design code improvements and verifications. - Conceptual design and analyses of a suitable safety system. As a result, the program shall enable a thorough assessment of the supercritical water cooled reactor system with a view to determine its future potential. This summary report shall give an overview of the contributions, which are planned to be provided by the EURATOM partners in France, Finland, Germany, Hungary, Switzerland, The Netherlands and The Czech Republic. (authors)

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

    PubMed

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

    2014-01-01

    Current research analyzing the effects of water in the field of homogeneous and heterogeneous reactions of organics in sub- and supercritical water are reviewed in this article. Since the physical properties of water (e.g., density, ion product and dielectric constants) can affect the reaction rates and mechanisms of various reactions, understanding the effects that water can have is important in controlling reactions. For homogeneous reactions, the effects of water on oxidation, hydrolysis, aldol condensation, Beckman rearrangement and biomass refining were introduced including recent experimental results up to 100 MPa using special pressure-resistance equipment. For heterogeneous reactions, the effects of ion product on acid/base-catalyzed reactions, such as hydrothermal conversion of biomass-related compounds, organic synthesis in the context of bio-refinery, and hydration of olefins were described and how the reaction paths are controlled by the concentration of water and hydrogen ions was summarized. PMID:23867097

  13. Core design study of a supercritical light water reactor with double row fuel rods

    SciTech Connect

    Zhao, C.; Wu, H.; Cao, L.; Zheng, Y.; Yang, J.; Zhang, Y.

    2012-07-01

    An equilibrium core for supercritical light water reactor has been designed. A novel type of fuel assembly with dual rows of fuel rods between water rods is chosen and optimized to get more uniform assembly power distributions. Stainless steel is used for fuel rod cladding and structural material. Honeycomb structure filled with thermal isolation is introduced to reduce the usage of stainless steel and to keep moderator temperature below the pseudo critical temperature. Water flow scheme with ascending coolant flow in inner regions is carried out to achieve high outlet temperature. In order to enhance coolant outlet temperature, the radial power distributions needs to be as flat as possible through operation cycle. Fuel loading pattern and control rod pattern are optimized to flatten power distribution at inner regions. Axial fuel enrichment is divided into three parts to control axial power peak, which affects maximum cladding surface temperature. (authors)

  14. Mass transfer in SCW extraction molecular diffusion and mass transfer coefficients of ketones and alkenes in sub- and supercritical water

    SciTech Connect

    Goemans, M.G.E.; Gloyna, E.F.

    1996-10-01

    The potential of sub- and supercritical water as extraction solvents has been demonstrated for the (reactive) extraction of coals, used car tires, organic species from residual aqueous solutions, and class selective extraction of organic pollutants with different polarities from solids. In addition, the potential of extraction of coal with supercritical aqueous solutions has been studied. However, physical transport in water at elevated temperature and pressures- and their impact on heterogenous reactions and (reactive) extraction -are not adequately understood. This situation is largely due to the limited data that is available for diffusion in high temperature, high pressure water mixture. Only the molecular diffusion of Iodine ions and hydroquinone in near-critical subcritical water and the self diffusion of coefficient of compressed supercritical water have been reported. In this paper, we present molecular diffusion coefficients of benzophenone, acetone, naphthalene, and anthracene in water at infinite dilution. Pressures ranged from 250 to 500 bar at temperatures ranging from 50{degrees}C to 500{degrees}C resulting in water densities ranging from 1000 to 150 kg/m{sup 3}. Diffusion coefficients were determined by the Taylor-Aris dispersion technique. The effects of increased diffusion on the mass transfer coefficients for emulsions and packed beds were quantified. Molecular division coefficients were 10 to 20 times faster in supercritical water than in water at ambient conditions. Experimental results were correlated with hydrodynamic and kinetic theory. This study and results to be published elsewhere show that diffusion-limited conditions are much more likely to be encountered in supercritical water than is commonly acknowledged.

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

    PubMed

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

    2013-10-01

    The supercritical water oxidation (SCWO) of industrial tannery sludge was investigated to understand the simultaneous destruction of organic pollutants and recovery of high content chromium. Experiments were performed in a batch reactor at temperatures of 350-500 °C, reaction time of 150-300 s and different oxygen ratios, to exhibit the effect of operation conditions. Results showed that removal efficiency of chemical oxygen demand (COD) increased with higher temperature, larger oxidant amount and reaction time; a maximum value of 96% was obtained. Meanwhile, destruction yield was much higher under supercritical conditions than that in subcritical water. In addition, removal efficiency of Cr from sludge reached more than 98% under all conditions; higher temperature played a positive role. Further, leaching toxicity tests of heavy metals in solid products were conducted based on toxicity characteristic leaching procedure. All heavy metals except nickel showed a greatly reduced leaching toxicity through their stabilization. The chromium oxide recovered in ash was amorphous below 550 °C, so that the structure of Cr could not be identified by X-ray diffraction pattern. Special attention should be paid on nickel as its leaching toxicity increased due to the corrosion of reactor surface under severe reaction conditions. PMID:23916746

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

    SciTech Connect

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

    2004-11-17

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

  17. Effective recovery of harmful metal ions from squid wastes using subcritical and supercritical water treatments.

    PubMed

    Tavakoli, Omid; Yoshida, Hiroyuki

    2005-04-01

    The Japanese common squid wastes contained high concentration of metal ions such as 31.7 ppm Cd(II), 264.0 ppm Cu(II), and 140.0 ppm Zn(II). The use of sub- and supercritical water treatment has been investigated as a new method of recovering heavy metals from squid wastes. The reactions were carried out in the temperature range of 443-653 K, a pressure range of 0.792-30 MPa, and reaction times of 1-40 min. The wastes were decomposed into soluble proteins, organic acids, amino acids, and so on in the aqueous phase, and the fat and oil were extracted by sub- and supercritical water. The maximum yields on concentration of Cd(II), Cu(II), and Zn(II) in the solid, fat, and oil phases were found at 653, 573, and 513-573 K, respectively. The aqueous phase showed the lowest concentration of the metal ions (0.05-0.5 ppm). The distribution coefficient of metal ions in the fat, solid, and oil phases to aqueous phase were examined and found highest in the fat phase (max. 48 000). The solid phase (max. 39,000) and oil phase (max. 245) showed the second and third highest. Moreover, the fat and oil phases produced during this method act as chelating agents to catch metal ions with an order of recovery of Cu2+ > Zn2+ > Cd2+ and Zn2+ > Cu2+ > Cd2+, respectively. PMID:15871276

  18. Total organic carbon disappearance kinetics for the supercritical water oxidation of monosubstituted phenols

    SciTech Connect

    Martino, C.J.; Savage, P.E.

    1999-06-01

    Supercritical water oxidation (SCWO) is a process technology for destroying organic compounds present in aqueous waste streams. The authors oxidized phenols bearing single -CH{sub 3}, -C{sub 2}H{sub 5}, -COCH{sub 3}, -CHO, -OH, -OCH{sub 3}, and -NO{sub 2} substituents in supercritical water at 460 C and 25.3 MPa. The observed effects of the concentrations of total organic carbon (TOC) and oxygen on the global disappearance rates for TOC were correlated by using power-law rate expressions. This kinetics study revealed that the rate of TOC disappearance is more sensitive to the oxygen concentration than is the rate of reactant disappearance. Additionally, the rate of TOC disappearance is always slower than the rate of reactant disappearance, with the ratio of these rates ranging from 0.10 to 0.65 for the different phenols at the conditions studied. The rates of TOC disappearance during SCWO of these substituted phenols varied by nearly 2 orders of magnitude, showing significant effects from both the identity and location of the substituent. These substituent effects are greater for TOC disappearance kinetics than for reactant disappearance kinetics. Additionally, all of the substituted phenols exhibit faster TOC disappearance rates than does phenol. Accordingly, phenol is a good worst case model compound for SCWO studies. The pronounced substituent effects for TOC disappearance rates indicate that the oxidation of a common refractory intermediate is not an important feature of the SCWO networks for these phenols at the conditions studied.

  19. SCC and corrosion evaluations of the F/M steels for a supercritical water reactor

    NASA Astrophysics Data System (ADS)

    Hwang, Seong Sik; Lee, Byung Hak; Kim, Jung Gu; Jang, Jinsung

    2008-01-01

    As one of the Generation IV nuclear reactors, a supercritical water cooled reactor (SCWR) is being considered as a candidate reactor due to its high thermal efficiency and simple reactor design without steam generators and steam separators. For the application of a structural material to a core's internals and a fuel cladding, the material should be evaluated in terms of its corrosion and stress corrosion cracking susceptibility. Stress corrosion cracking and general corrosion tests of ferritic-martensitic (F/M) steels, high Ni alloys and an oxide dispersion strengthened (ODS) alloy were performed. Stress corrosion cracking (SCC) was not observed on the fractured surface of the T 91 steel in the supercritical water at 500, 550 and 600 °C. As the test temperature increased, the ultimate tensile strength (UTS) and yield strength (YS) of T 91 decreased, and a high dissolved oxygen level induced corrosion and low ductility. The F/M steels showed a high corrosion rate whereas the Ni base alloys showed a little corrosion at 500 and 550 °C. Corrosion rate of the F/M steels at 600 °C test was up to three times larger than that at 500 °C. A thin layer composed of Mo and Ni seems to retard the Cr diffusion into the out layer of the corrosion product of T 92 and T 122.

  20. Destruction of Representative Navy Wastes Using Supercritical Water Oxidation. Final report

    SciTech Connect

    Rice, S.F.; Steeper, R.R.; LaJeunesse, C.A.

    1993-10-01

    Supercritical water oxidation (SCWO) is a rapidly emerging technology that presents potential as a hazardous waste treatment method for a wide variety of industrial chemicals ranging from common organic solvents to complex formulations such as paints, lubricating oils, and degreasers. The Naval Civil Engineering Laboratory is contributing to the development of this technology for application to waste materials generated at naval shipyards and bases. These wastes include paint stripping and changeout fluids generated from equipment service procedures as well as herbicides, pesticides, paint, and numerous other materials associated with base facility maintenance. An important design consideration in the development of SCWO systems centers on choosing a reactor operating temperature such that the destruction of the waste organic is sufficiently complete. This report examines the temperature dependence of the oxidation in supercritical water of seven common organic compounds and three industrial commercial materials over the temperature range of 430{degree}C to 585{degree}C and reaction times ranging from seven to thirty seconds at a pressure of 27.5 MPa (4000 psi). The materials studies are methanol, phenol, methyl ethyl ketone, ethylene glycol, acetic acid, methylene chloride, 1,1,1-tichloroethane (TCA), latex paint, motor oil, and Roundup, a commercial general purpose herbicide. The results indicate that for most materials, temperatures over 530{degree}C and residence times near 20 seconds afford destruction efficiencies of greater than 99.95%

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

    SciTech Connect

    Philip E. MacDonald

    2003-09-01

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

  2. Migration behavior of supercritical and liquid CO2 in a stratified system: Experiments and numerical simulations

    NASA Astrophysics Data System (ADS)

    Oh, Junho; Kim, Kue-Young; Han, Weon Shik; Park, Eungyu; Kim, Jeong-Chan

    2015-10-01

    Multiple scenarios of upward CO2 migration driven by both injection-induced pressure and buoyancy force were investigated in a horizontally and vertically stratified core utilizing a core-flooding system with a 2-D X-ray scanner. Two reservoir-type scenarios were considered: (1) the terrestrial reservoir scenario (10 MPa and 50°C), where CO2 exists in a supercritical state and (2) the deep-sea sediment reservoir scenario (28 MPa and 25°C), where CO2 is stored in the liquid phase. The core-flooding experiments showed a 36% increase in migration rate in the vertical core setting compared with the horizontal setting, indicating the significance of the buoyancy force under the terrestrial reservoir scenario. Under both reservoir conditions, the injected CO2 tended to find a preferential flow path (low capillary entry pressure and high-permeability (high-k) path) and bypass the unfavorable pathways, leaving low CO2 saturation in the low-permeability (low-k) layers. No distinctive fingering was observed as the CO2 moved upward, and the CO2 movement was primarily controlled by media heterogeneity. The CO2 saturation in the low-k layers exhibited a more sensitive response to injection rates, implying that the increase in CO2 injection rates could be more effective in terms of storage capacity in the low-k layers in a stratified reservoir. Under the deep-sea sediment condition, the storage potential of liquid CO2 was more than twice as high as that of supercritical CO2 under the terrestrial reservoir scenario. In the end, multiphase transport simulations were conducted to assess the effects of heterogeneity on the spatial variation of pressure buildup, CO2 saturation, and CO2 flux. Finally, we showed that a high gravity number (Ngr) tended to be more influenced by the heterogeneity of the porous media.

  3. 'Structure, Dynamics and Vibrational Spectrum of Supercritical CO2/H2O Mixtures from Ab Initio Molecular Dynamics as a Function of Water Cluster Formation

    SciTech Connect

    Glezakou, Vassiliki Alexandra; Rousseau, Roger J.; Dang, Liem X.; McGrail, B. Peter

    2010-08-21

    We have studied the effect of water in the supercritical phase of CO2 as a function of water self-association using DFT-based molecular dynamics simulations. The dependence of the intermolecular and intramolecular structure and dynamic properties upon water concentration in the supercritical CO2/H2O phase at a density of 0.81g/cm3 and temperature of 318.15K is investigated in detail and compared to previous studies of the pure sc-CO2 system and Monte-Carlo simulations of water in sc-CO2 phase. Analysis of radial and orientational distribution functions of the intermolecular interactions shows that the presence of water molecules does not disturb the previously established distorted T-shaped orientation of CO2 molecules, though there is strong evidence of perturbation of the second shell structure which enhances the preference for the slipped parallel orientation in this region. There is also evidence of short-lived hydrogen bonds between CO2 and water molecules. For higher water concentrations, water clustering is observed, consistent with the expected phase separation under these conditions of temperature and pressure. Finally, the water-water and water-CO2 interactions are discussed and analyzed in terms of the water self-association and thermodynamic quantities derived from the corresponding radial distribution functions. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  4. Numerical Simulations Studies of the Convective Instability Onset in a Supercritical Fluid

    NASA Technical Reports Server (NTRS)

    Furukawa, A.; Meyer, H.; Onuki, A.

    2004-01-01

    Numerical simulation studies are reported for the convection of a supercritical fluid, He-3, in a Rayleigh-Benard cell. The calculations provide the temporal profile DeltaT(t) of the temperature drop across the fluid layer. In a previous article, systematic delays in the onset of the convective instability in simulations relative to experiments were reported, as seen from the DeltaT(t) profiles. They were attributed to the smallness of the noise which is needed to start the instability. Therefore i) homogeneous temperature noise and ii) spatial lateral periodic temperature variations in the top plate were programmed into the simulations, and DeltaT(t) compared with that of an experiment with the same fluid parameters. An effective speed-up in the instability onset was obtained, with the best results obtained through the spatial temperature variations with a period of 2L, close to the wavelength of a pair of convections rolls. For a small amplitude of 0.5 micro-K, this perturbation gave a semiquantitative agreement with experimental observations. Results for various noise amplitudes are presented and discussed in relation to predictions by El Khouri and Carl es.

  5. Gasification characteristics of an activated carbon catalyst during the decomposition of hazardous waste material in supercritical water

    SciTech Connect

    Matsumura, Yukihiko; Nuessle, F.W.; Antal, M.J. Jr.

    1996-12-31

    Recently, carbonaceous materials including activated carbon were proven to be effective catalysts for hazardous waste gasification in supercritical water. Using coconut shell activated carbon catalyst, complete decomposition of industrial organic wastes including methanol and acetic acid was achieved. During this process, the total mass of the activated carbon catalyst changes by two competing processes: a decrease in weight via gasification of the carbon by supercritical water, or an increase in weight by deposition of carbonaceous materials generated by incomplete gasification of the biomass feedstocks. The deposition of carbonaceous materials does not occur when complete gasification is realized. Gasification of the activated carbon in supercritical water is often favored, resulting in changes in the quality and quantity of the catalyst. To thoroughly understand the hazardous waste decomposition process, a more complete understanding of the behavior of activated carbon in pure supercritical water is needed. The gasification rate of carbon by water vapor at subcritical pressures was studied in relation to coal gasification and generating activated carbon.

  6. Effect of impurities on the corrosion behavior of CO2 transmission pipeline steel in supercritical CO2-water environments.

    PubMed

    Choi, Yoon-Seok; Nesic, Srdjan; Young, David

    2010-12-01

    The corrosion property of carbon steel was evaluated using an autoclave under CO(2)-saturated water phase and water-saturated CO(2) phase with impurities (O(2) and SO(2)) at 80 bar CO(2) and 50 °C to simulate the condition of CO(2) transmission pipeline in the carbon capture and storage (CCS) applications. The results showed that the corrosion rate of carbon steel in CO(2)-saturated water was very high and it increased with adding O(2) in the system due to the inhibition effect of O(2) on the formation of protective FeCO(3). It is noteworthy that corrosion took place in the water-saturated CO(2) phase under supercritical condition when no free water is present. The addition of O(2) increased the corrosion rates of carbon steel in water-saturated CO(2) phase. The addition of 0.8 bar SO(2) (1%) in the gas phase dramatically increased the corrosion rate of carbon steel from 0.38 to 5.6 mm/y. This then increased to more than 7 mm/y with addition of both O(2) and SO(2). SO(2) can promote the formation of iron sulfite hydrate (FeSO(3)·3H(2)O) on the steel surface which is less protective than iron carbonate (FeCO(3)), and it is further oxidized to become FeSO(4) and FeOOH when O(2) is present with SO(2) in the CO(2)-rich phase. The corrosion rates of 13Cr steel were very low compared with carbon steel in CO(2)-saturated water environments with O(2), whereas it was as high as carbon steel in a water-saturated CO(2) phase with O(2) and SO(2). PMID:21049923

  7. Synthesizing and dispersing silver nanoparticles in a water-in-supercritical carbon dioxide microemulsion

    SciTech Connect

    Ji, M.; Chen, X.; Wai, C.M.; Fulton, J.L.

    1999-03-24

    Reverse micelles and microemulsions formed in liquid and supercritical carbon dioxide (CO{sub 2}) allow highly polar or polarizable compounds to be dispersed in this nonpolar fluid. However, since the polarizability per unit volume of dense CO{sub 2} is quite low, it is difficult to overcome the strong van der Waals attractive interactions between particles in order to stably suspend macromolecular species. Conventional surfactants by themselves do not form reverse micelles or microemulsions in CO{sub 2} because the van der Waals interdroplet attractions are too high. The use of surfactants or cosurfactants with fluorinated tails provides a layer of a weakly attractive compound covering the highly attractive droplet cores, thus preventing their short-range interactions that would destabilize the system. Using this strategy, the authors describe a method to synthesize and stabilize metallic silver nanoparticles having diameters from 5 to 15 nm in supercritical CO{sub 2} using an optically transparent, water-in-CO{sub 2} microemulsion.

  8. Determination of pure neutron radiolysis yields for use in chemical modeling of supercritical water

    NASA Astrophysics Data System (ADS)

    Edwards, Eric J.

    This work has determined pure neutron radical yields at elevated temperature and pressure up to supercritical conditions using a reactor core radiation. The data will be necessary to provides realistic conditions for material corrosion experiments for the supercritical water reactor (SCWR) through water chemistry modeling. The work has been performed at the University of Wisconsin Nuclear Reactor using an apparatus designed to transport supercritical water near the reactor core. Low LET yield data used in the experiment was provided by a similar project at the Notre Dame Radiation Lab. Radicals formed by radiolysis were measured through chemical scavenging reactions. The aqueous electron was measured by two methods, a reaction with N2O to produce molecular nitrogen and a reaction with SF6 to produce fluoride ions. The hydrogen radical was measured through a reaction with ethanol-D6 (CD3CD2OD) to form HD. Molecular hydrogen was measured directly. Gaseous products were measured with a mass spectrometer and ions were measured with an ion selective electrode. Radiation energy deposition was calibrated for neutron and gamma radiation separately with a neutron activation analysis and a radiolysis experiment. Pure neutron yields were calculated by subtracting gamma contribution using the calibrated gamma energy deposition and yield results from work at the Notre Dame Radiation Laboratory. Pure neutron yields have been experimentally determined for aqueous electrons from 25°C to 400°C at 248 bar and for the hydrogen radical from 25°C to 350°C at 248 bar, Isothermal data has been acquired for the aqueous electron at 380°C and 400°C as a function of density. Molecular hydrogen yields were measured as a function of temperature and pressure, although there was evidence that chemical reactions with the walls of the water tubing were creating molecular hydrogen in addition to that formed through radiolysis. Critical hydrogen concentration behavior was investigated but a

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

    SciTech Connect

    Antal, M.J. Jr.; Matsumura, Y.; Onuma, M.T.

    1995-09-01

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

  10. Simulation of Oxygen Disintegration and Mixing With Hydrogen or Helium at Supercritical Pressure

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Taskinoglu, Ezgi

    2012-01-01

    The simulation of high-pressure turbulent flows, where the pressure, p, is larger than the critical value, p(sub c), for the species under consideration, is relevant to a wide array of propulsion systems, e.g. gas turbine, diesel, and liquid rocket engines. Most turbulence models, however, have been developed for atmospheric-p turbulent flows. The difference between atmospheric-p and supercritical-p turbulence is that, in the former situation, the coupling between dynamics and thermodynamics is moderate to negligible, but for the latter it is very significant, and can dominate the flow characteristics. The reason for this stems from the mathematical form of the equation of state (EOS), which is the perfect-gas EOS in the former case, and the real-gas EOS in the latter case. For flows at supercritical pressure, p, the large eddy simulation (LES) equations consist of the differential conservation equations coupled with a real-gas EOS. The equations use transport properties that depend on the thermodynamic variables. Compared to previous LES models, the differential equations contain not only the subgrid scale (SGS) fluxes, but also new SGS terms, each denoted as a correction. These additional terms, typically assumed null for atmospheric pressure flows, stem from filtering the differential governing equations, and represent differences between a filtered term and the same term computed as a function of the filtered flow field. In particular, the energy equation contains a heat-flux correction (q-correction) that is the difference between the filtered divergence of the heat flux and the divergence of the heat flux computed as a function of the filtered flow field. In a previous study, there was only partial success in modeling the q-correction term, but in this innovation, success has been achieved by using a different modeling approach. This analysis, based on a temporal mixing layer Direct Numerical Simulation database, shows that the focus in modeling the q

  11. The thermal circuit of a nuclear power station's unit built around a supercritical-pressure water-cooled reactor

    NASA Astrophysics Data System (ADS)

    Silin, V. A.; Zorin, V. M.; Tagirov, A. M.; Tregubova, O. I.; Belov, I. V.; Povarov, P. V.

    2010-12-01

    Main results obtained from calculations of the steam generator and thermal circuit of the steam turbine unit for a nuclear power unit with supercritical-pressure water coolant and integral layout are presented. The obtained characteristics point to the advisability of carrying out further developments of this promising nuclear power technology.

  12. Effects of water on enzyme performance with an emphasis on the reactions in supercritical fluids.

    PubMed

    Rezaei, K; Jenab, E; Temelli, F

    2007-01-01

    Enzymes require a certain level of water in their structures in order to maintain their natural conformation, allowing them to deliver their full functionality. Furthermore, as a modifier of the solvent, up to a certain level, water can modify the solvent properties such as polarity/polarizability as well as the solubility of the reactants and the products. In addition, depending on the type of the reaction, water can be a substrate (e.g., in hydrolysis) or a product (e.g., in esterolysis) of the enzymatic reaction, influencing the enzyme turnover in different ways. It is found that regardless of the type of reaction, the functionality of enzyme itself is maximum at an optimum level of water, beyond which the enzyme performance is declined due to the loss in enzyme stability. Furthermore, mass transfer limitations caused by pathway blockage and/or by reduced solubilities of the reactants and/or products can also affect the enzyme performance at higher water levels. Controlling water content of ingoing CO2 and substrates as well as precise management of enzyme support and salt hydrates are important strategies to adjust water level in reaction media, especially in supercritical environments. PMID:18085461

  13. Magnetic ramp scale at supercritical perpendicular collisionless shocks: Full particle electromagnetic simulations

    SciTech Connect

    Yang, Zhongwei; Lu, Quanming; Gao, Xinliang; Huang, Can; Yang, Huigen; Hu, Hongqiao; Han, Desheng; Liu, Ying

    2013-09-15

    Supercritical perpendicular collisionless shocks are known to exhibit foot, ramp, and overshoot structures. The shock ramp structure is in a smaller scale in contrast to other microstructures (foot and overshoot) within the shock front. One-dimensional full particle simulations of strictly perpendicular shocks over wide ranges of ion beta β{sub i}, Alfvén Mach number M{sub A}, and ion-to-electron mass ratio m{sub i}/m{sub e} are presented to investigate the impact of plasma parameters on the shock ramp scale. Main results are (1) the ramp scale can be as small as several electron inertial length. (2) The simulations suggest that in a regime below the critical ion beta value, the shock front undergoes a periodic self-reformation and the shock ramp scale is time-varying. At higher ion beta values, the shock front self-reformation is smeared. At still higher ion beta value, the motion of reflected ions is quite diffuse so that they can lead to a quasi-steady shock ramp. Throughout the above three conditions, the shock ramp thickness increases with β{sub i}. (3) The increase (decrease) in Mach number and the decrease (increase) in the beta value have almost equivalent impact on the state (i.e., stationary or nonstationary) of the shock ramp. Both of front and ramp thicknesses are increased with M{sub A}.

  14. Ion Pair Asociation in Ultra Supercritical Aqueous Environments: Successful Interplay between Conductance Experiment, Theory and Molecular Simulation.

    SciTech Connect

    Chialvo, Ariel A; Gruszkiewicz, Miroslaw {Mirek} S; Cole, David R

    2010-01-01

    We discuss the interplay between theory, molecular simulation and electric conductance experiments as an important tool for the extraction of ion-pair interaction potentials to make possible the bridging of the density gap between the lowest experimentally attainable conductance measurement and the theoretically reachable zero-density limit of the ion-pair association constant. Then, we predict the density dependence of the Na+!Cl! pair association constant in ultra supercritical steam environments by constraint molecular dynamics simulation over state conditions relevant to the new generation of ultra-supercritical steam power plants. Finally, we draw attention to relevant modeling challenges associated to the behavior of these systems around the zero-density limit and discuss ways to overcome them.

  15. Three-dimensional simulations of supercritical black hole accretion discs - luminosities, photon trapping and variability

    NASA Astrophysics Data System (ADS)

    Sądowski, Aleksander; Narayan, Ramesh

    2016-03-01

    We present a set of four three-dimensional, general relativistic, radiation magnetohydrodynamical simulations of black hole accretion at supercritical mass accretion rates, dot{M} > dot{M}_Edd. We use these simulations to study how disc properties are modified when we vary the black hole mass, the black hole spin, or the mass accretion rate. In the case of a non-rotating black hole, we find that the total efficiency is of the order of 3 per cent dot{M} c^2, approximately a factor of 2 less than the efficiency of a standard thin accretion disc. The radiation flux in the funnel along the axis is highly super-Eddington, but only a small fraction of the energy released by accretion escapes in this region. The bulk of the 3 per cent dot{M} c^2 of energy emerges farther out in the disc, either in the form of photospheric emission or as a wind. In the case of a black hole with a spin parameter of 0.7, we find a larger efficiency of about 8 per cent dot{M} c^2. By comparing the relative importance of advective and diffusive radiation transport, we show that photon trapping is effective near the equatorial plane. However, near the disc surface, vertical transport of radiation by diffusion dominates. We compare the properties of our fiducial three-dimensional run with those of an equivalent two-dimensional axisymmetric model with a mean-field dynamo. The latter simulation runs nearly 100 times faster than the three-dimensional simulation, and gives very similar results for time-averaged properties of the accretion flow, but does not reproduce the time-variability.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  17. Catalysis of CuSO4 for total organic carbon detection based on supercritical water oxidation.

    PubMed

    Hui, Zhang; Dongdong, Han; Yi, Chen; Chunmian, Lin

    2016-01-01

    The catalytic effects of CuSO4 in total organic carbon (TOC) detecting processes based on supercritical water oxidation have been investigated. Using benzoic acid as a model pollutant, the presence of a CuSO4 catalyst can significantly decrease the reaction temperature and H2O2 multiple during the TOC detection processes. A better TOC conversion efficiency was obtained at a much lower temperature in the catalytic system compared with the non-catalytic condition. The use of the catalyst effectively lowered the necessary H2O2 multiple from 20.0 without catalyst to 3.0 in the catalytic system. The established device could detect the TOC concentration precisely in model wastewater without inorganic carbon (IC). Moreover, the detection of the practical wastewater was studied. Detection results were total carbon of wastewater rather than TOC of practical wastewater. A detection or removal unit of IC is necessary before it can be practically utilized. PMID:27438232

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

    NASA Astrophysics Data System (ADS)

    Hu, H. L.; Zhou, Z. J.; Liao, L.; Zhang, L. F.; Wang, M.; Li, S. F.; Ge, C. C.

    2013-06-01

    The corrosion behavior of a 14Cr-ODS steel in the supercritical water was investigated using a variety of characterization techniques. Compared with 316L austenitic steel, the 14Cr-ODS steel had better corrosion resistant property. As the increasing of the exposure time, the weight gain increased, but the corrosion rates decreased. The curve of weight gain as a function of time followed a parabolic law. The general weight gain was 0.3476 mg/(dm2 h). A triple layer was observed which consisted of an outer layer, an inner layer and a diffusion layer. The outer layer was iron rich and contained Fe3O4, on which pores were observed. The inner layer and diffusion layer contained mainly (Fe,Cr2)O4. The oxidation mechanism was also discussed.

  19. Experimental study of crossover from capillary to viscous fingering for supercritical CO2-water displacement in a homogeneous pore network.

    PubMed

    Wang, Ying; Zhang, Changyong; Wei, Ning; Oostrom, Mart; Wietsma, Thomas W; Li, Xiaochun; Bonneville, Alain

    2013-01-01

    Carbon sequestration in saline aquifers involves displacing brine from the pore space by supercritical CO(2) (scCO(2)). The displacement process is considered unstable due to the unfavorable viscosity ratio between the invading scCO(2) and the resident brine. The mechanisms that affect scCO(2)-water displacement under reservoir conditions (41 °C, 9 MPa) were investigated in a homogeneous micromodel. A large range of injection rates, expressed as the dimensionless capillary number (Ca), was studied in two sets of experiments: discontinuous-rate injection, where the micromodel was saturated with water before each injection rate was imposed, and continuous-rate injection, where the rate was increased after quasi-steady conditions were reached for a certain rate. For the discontinuous-rate experiments, capillary fingering and viscous fingering are the dominant mechanisms for low (logCa ≤ -6.61) and high injection rates (logCa ≥ -5.21), respectively. Crossover from capillary to viscous fingering was observed for logCa = -5.91 to -5.21, resulting in a large decrease in scCO(2) saturation. The discontinuous-rate experimental results confirmed the decrease in nonwetting fluid saturation during crossover from capillary to viscous fingering predicted by numerical simulations by Lenormand et al. (J. Fluid Mech.1988, 189, 165-187). Capillary fingering was the dominant mechanism for all injection rates in the continuous-rate experiment, resulting in monotonic increase in scCO(2) saturation. PMID:22676368

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

    SciTech Connect

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

    2015-09-15

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

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

    SciTech Connect

    SPRITZER,M; HONG,G

    2005-01-01

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

  2. Pulse radiolysis of supercritical water I. Ractions between hydrophobic and anionic species.

    SciTech Connect

    Cline, J.; Takahashi, K.; Marin, T. W.; Jonah, C. D.; Bartels, D. M.; Chemistry

    2002-12-26

    Reaction rates of solvated electrons with oxygen and with sulfur hexafluoride were measured in hydrothermal and supercritical water using transient absorption spectroscopy and electron pulse radiolysis. Under alkaline conditions, the reaction of hydrogen atoms with hydroxide ions to generate solvated electrons was also observed in the presence of the SF{sub 6} scavenger. At temperatures below 300 C, the rate constants for scavenging by O{sub 2} or SF{sub 6} follow Arrhenius behavior but become increasingly dependent on water density (pressure) at higher temperatures. Above 100 C, the rate constant for the H reaction with OH- falls well below the numbers extrapolated from the Arrhenius behavior in the one atmosphere liquid. At a fixed temperature above the water critical temperature (380 C, T/T{sub c}=1.01), rate constants for all three reactions reach a distinct minimum near 0.45 g/cm3. We propose an explanation for this behavior in terms of the potential of mean force separating an ion (OH- or (e-)aq) from a hydrophobic species (H, O{sub 2}, or SF{sub 6}) in the compressible fluid. The data also reveal an increasing initial yield of atomic hydrogen relative to solvated electrons as water density decreases. The initial yield of H appears to surpass that of solvated electrons when the water density is below 0.6 g/cm3 at 380 C.

  3. Simulated distillation of petroleum and coal-derived products by packed capillary supercritical fluid chromatography

    SciTech Connect

    Robson, M.; Johnson, B.R.; Mitchell, S.C.

    1995-12-31

    The advantages of simulated distillation (SD) of petroleum compounds by super-critical fluid chromatography (SFC) over high temperature gas chromatography (HTGC) are well recognised. Most of the research performed using this technique has employed conventional open tubular columns but the use of packed capillary columns which offer high sample capacities, greater efficiency of separation and a shorter analysis time has recently received much attention. Previous work at Leeds using a variety of column packings (C{sub 1}-C{sub 18} alkyl groups bonded to silica) has demonstrated that high molecular weight hydrocarbons with boiling points up to 800{degrees}C can be successfully eluted with pure CO{sub 2} as a mobile phase. However, the high compositional variability of coal-derived samples increases the difficulty of SD-SFC of coal fractions as compared to petroleum derived fractions. In this study, a number of coal samples have been investigated to determine the suitability of packed capillary SD-SFC for heavy coal products.

  4. Effect of Sub- and Super-critical Water Treatment on Physicochemical Properties of Porcine Skin

    PubMed Central

    2015-01-01

    Super- and sub-critical water treatments have been of interest as novel methods for protein hydrolysis. In the present study, we studied the effect of sub-critical water (Sub-H2O, 300℃, 80 bar) treatment as well as super-critical water (Super-H2O, 400℃, 280 bar) treatment on the physicochemical properties of porcine skin (PS), which has abundant collagen. Porcine skin was subjected to pre-thermal treatment by immersion in water at 70℃, and then treated with sub- or super-critical water. Physicochemical properties of the hydrolysates, such as molecular weight distribution, free amino acid content, amino acid profile, pH, color, and water content were determined. For the molecular weight distribution analysis, 1 kDa hydrolyzed porcine skin (H-PS) was produced by Super-H2O or Sub-H2O treatment. The free amino acid content was 57.18 mM and 30.13 mM after Sub-H2O and Super-H2O treatment, respectively. Determination of amino acid profile revealed that the content of Glu (22.5%) and Pro (30%) was higher after Super-H2O treatment than after Sub-H2O treatment, whereas the content of Gly (28%) and Ala (13.1%) was higher after Sub-H2O treatment. Super-H2O or Sub-H2O treatment affected the pH of PS, which changed from 7.29 (Raw) to 9.22 (after Sub-H2O treatment) and 9.49 (after Super-H2O treatment). Taken together, these results showed that Sub-H2O treatment was slightly more effective for hydrolysis than Super-H2O was. However, both Sub-H2O and Super-H2O treatments were effective processing methods for hydrolysis of PS collagen in a short time and can be regarded as a green chemistry technology. PMID:26761798

  5. Direct numerical simulations of supercritical fluid mixing layers applied to heptane nitrogen

    NASA Astrophysics Data System (ADS)

    Miller, Richard S.; Harstad, Kenneth G.; Bellan, Josette

    2001-06-01

    Direct numerical simulations (DNS) are conducted of a model hydrocarbon nitrogen mixing layer under supercritical conditions. The temporally developing mixing layer configuration is studied using heptane and nitrogen supercritical fluid streams at a pressure of 60 atm as a model system related to practical hydrocarbon-fuel/air systems. An entirely self-consistent cubic Peng Robinson equation of state is used to describe all thermodynamic mixture variables, including the pressure, internal energy, enthalpy, heat capacity, and speed of sound along with additional terms associated with the generalized heat and mass transport vectors. The Peng Robinson formulation is based on pure-species reference states accurate to better than 1% relative error through comparisons with highly accurate state equations over the range of variables used in this study (600 [less-than-or-eq, slant] T [less-than-or-eq, slant] 1100 K, 40 [less-than-or-eq, slant] p [less-than-or-eq, slant] 80 atm) and is augmented by an accurate curve fit to the internal energy so as not to require iterative solutions. The DNS results of two-dimensional and three-dimensional layers elucidate the unique thermodynamic and mixing features associated with supercritical conditions. Departures from the perfect gas and ideal mixture conditions are quantified by the compression factor and by the mass diffusion factor, both of which show reductions from the unity value. It is found that the qualitative aspects of the mixing layer may be different according to the specification of the thermal diffusion factors whose value is generally unknown, and the reason for this difference is identified by examining the second-order statistics: the constant Bearman Kirkwood (BK) thermal diffusion factor excites fluctuations that the constant Irwing Kirkwood (IK) one does not, and thus enhances overall mixing. Combined with the effect of the mass diffusion factor, constant positive large BK thermal diffusion factors retard

  6. Limestone-particle-stabilized macroemulsion of liquid and supercritical carbon dioxide in water for ocean sequestration.

    PubMed

    Golomb, D; Barry, E; Ryan, D; Lawton, C; Swett, P

    2004-08-15

    When liquid or supercritical CO2 is mixed with an aqueous slurry of finely pulverized (1-20 microm) limestone (CaCO3) in a high-pressure reactor, a macroemulsion is formed consisting of droplets of CO2 coated with a sheath of CaCO3 particles dispersed in water. The coated droplets are called globules. Depending on the globule diameter and the CaCO3 sheath thickness, the globules sink to the bottom of the water column, are neutrally buoyant, or float on top of the water. The CaCO3 particles are lodged at the CO2/ H2O interface, preventing the coalescence of the CO2 droplets, and thus stabilizing the CO2-in-water emulsion. We describe the expected behavior of a CO2/H2O/CaCO3 emulsion plume released in the deep ocean for sequestration of CO2 in the ocean to ameliorate global warming. Depending on the amount of CO2 injected, the dense plume will descend a few hundred meters while entraining ambient seawater until it acquires neutral buoyancy in the stratified ocean. After equilibration, the globules will rain out from the plume toward the ocean bottom. This mode of CO2 release will prevent acidification of the seawater around the release point, which is a major environmental drawback of ocean sequestration of liquid, unemulsified CO2. PMID:15382876

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Rueslåtten, H.; Hovland, M. T.

    2010-12-01

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

  9. Kinetics and products from o-cresol oxidation in supercritical water

    SciTech Connect

    Martino, C.J.; Savage, P.E.; Kasiborski, J.

    1995-06-01

    Dilute aqueous solutions of o-cresol (2-methylphenol) were oxidized in a tubular flow reactor at near-critical and supercritical conditions. The power-law rate expression that best correlates the kinetics of o-cresol disappearance is rate = 10{sup 5.7} exp({minus}29,700/RT)[o-cresol]{sup 0.57}[O{sub 2}]{sup 0.22}[H{sub 2}O]{sup 1.44}. The power-law rate expression that best correlates the experimental results for the conversion of organic carbon to CO{sub 2} is rate = 10{sup 6.8} exp({minus}34,000/RT)[TOC]{sup 0.34}[O{sub 2}]{sup 0.73}[H{sub 2}O]{sup 1.18}. All concentrations are in moles per liter, the activation energy is in calories per mole, and the rate is in moles per liter per second. The most abundant products from o-cresol oxidation were typically phenol, 2-hydroxybenzaldehyde, 1,3-benzodioxole, indanone, CO, and CO{sub 2}. 2-Hydroxybenzaldehyde was the major primary product. A reanalysis of published kinetics data for the oxidation of two other ring-containing compounds (pyridine and 4-chlorophenol) in supercritical water revealed that the rate laws previously reported for these two compounds do not provide the best correlation of the experimental data. The authors report the new rate laws, which are similar to those for o-cresol, 2-chlorophenol, and phenol in that the global reaction orders are between 0.55 and 0.9 for the organic compounds and between 0.2 and 0.5 for oxygen.

  10. Local density augmentation of supercritical water probed by 4,4‧-bpyHrad radical: A pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Fang, Zhong; Muroya, Yusa; Fu, Haiying; Yan, Yu; Katsumura, Yosuke; Lin, Mingzhang

    2016-07-01

    Solvatochromic shift of 4,4‧-bpyHrad in aqueous solutions at elevated temperatures up to supercritical conditions and in various organic solvents with different dielectric constants, is investigated by pulse-radiolysis technique. 4,4‧-bpyHrad shows a stronger solvent-solute interaction in water than in organic solvents, perhaps due to the hydrogen bond between 4,4‧-bpyHrad and water. At 380 °C, local density augmentation, namely ρlocal-ρbulk, in supercritical water becomes 280 kg m-3 (ρbulk = 208 kg m-3), and the density enhancement factor is 8.9. Density fluctuation maximizes when ρbulk is around 120 kg m-3. Density inhomogeneity decreases as temperature rises, but is still remarkable at 400 °C.

  11. Evaluation of tubular reactor designs for supercritical water oxidation of U.S. Department of Energy mixed waste

    SciTech Connect

    Barnes, C.M.

    1994-12-01

    Supercritical water oxidation (SCWO) is an emerging technology for industrial waste treatment and is being developed for treatment of the US Department of Energy (DOE) mixed hazardous and radioactive wastes. In the SCWO process, wastes containing organic material are oxidized in the presence of water at conditions of temperature and pressure above the critical point of water, 374 C and 22.1 MPa. DOE mixed wastes consist of a broad spectrum of liquids, sludges, and solids containing a wide variety of organic components plus inorganic components including radionuclides. This report is a review and evaluation of tubular reactor designs for supercritical water oxidation of US Department of Energy mixed waste. Tubular reactors are evaluated against requirements for treatment of US Department of Energy mixed waste. Requirements that play major roles in the evaluation include achieving acceptable corrosion, deposition, and heat removal rates. A general evaluation is made of tubular reactors and specific reactors are discussed. Based on the evaluations, recommendations are made regarding continued development of supercritical water oxidation reactors for US Department of Energy mixed waste.

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

    PubMed

    Okajima, Idzumi; Sako, Takeshi

    2014-01-01

    Exploiting unused or waste biomass as an alternative fuel is currently receiving much attention because of the potential reductions in CO2 emissions and the lower cost in comparison to expensive fossil fuels. If we are to use biomass domestically or industrially, we must be able to convert biomass to high-quality and easy-to-use liquid, gas, or solid fuels that have high-calorific values, low moisture and ash contents, uniform composition, and suitable for stored over long periods. In biomass treatment, hot and high-pressure water including supercritical and subcritical water is an excellent solvent, as it is clean and safe and its action on biomass can be optimized by varying the temperature and pressure. In this article, the conversion of waste biomass to fuel using hot and high-pressure water is reviewed, and the following examples are presented: the production of large amounts of hydrogen from waste biomass, the production of cheap bioethanol from non-food raw materials, and the production of composite powder fuel from refractory waste biomass in the rubble from the Great East Japan Earthquake. Several promising techniques for the conversion of biomass have been demonstrated in large-scale plants and commercial deployment is expected in the near future. PMID:23867098

  13. Oxidation of phenolics in supercritical water. Quarterly technical progress report, September 1, 1993--November 30, 1993

    SciTech Connect

    Savage, P.E.

    1993-12-31

    Oxidation reactions are accomplished in an isothermal, high-pressure, flow reactor designed specifically for operation at supercritical water conditions. The reactor feed stream is prepared by mixing two separate streams. One stream is an aqueous solution of the phenolic reactant and the second stream is water with dissolved oxygen. Controlling the flow rates of these two streams allows us to control the reactor residence time and the relative amounts of the phenol and oxygen fed to the reactor. The reactor effluent is cooled and depressorized and then collected for analysis. The gaseous products are analyzed by gas chromatography (GC). The liquid-phase products are analyzed by GC, high-performance liquid chromatography, and GC-mass spectrometry. Our work to date has focused on the oxidation of cresols in SCW. We have explored the effects of temperature, pressure, and the concentrations of o-cresol, oxygen, and water. Table I gives these experimental conditions and the resulting ocresol conversions. We reported a portion of this data in our previous quarterly report. New information is given in the last three columns where we report the molar yields of phenol, CO{sub 2}, and CO. Molar yields were calculated as the molar flow rate of a given product divided by the initial molar flow rate of o-cresol and normalized by the stoichiometric coefficient. Earlier, we used the o-cresol conversion data to determine the parameters in a global reaction rate law for o-cresol disappearance.

  14. Oxidation and hydrolysis of acetic acid and methylene chloride in supercritical water as a means of remediation

    SciTech Connect

    Marrone, P.A.; Lachance, R.P.; DiNaro, J.L.

    1995-10-01

    Supercritical water oxidation (SCWO) is a promising technology proposed for the destruction of hazardous organic wastes. Unlike its well known behavior under ambient conditions, water above its critical point (374{degrees}C, 221 bar) has properties similar to that of a nonpolar solvent, primarily due to the effect of a decrease in hydrogen bonding and density that occurs near and above the critical point. The result is that nonpolar organics and oxygen exhibit complete solubility in supercritical water, while polar species such as inorganic salts are insoluble and precipitate out. In the single homogeneous phase formed, oxidation of organics with oxygen in supercritical water is rapid and complete to CO{sub 2} and H{sub 2}O. Organic heteroatoms such as halogens, sulfur, or phosphorus are converted to inorganic acids (HCl, H{sub 2}SO{sub 4}, H{sub 3}PO{sub 4}) which precipitate as salts when neutralized with added base, while nitrogen is converted to N{sub 2} and N{sub 2}O. No NO{sub x} compounds are formed due to the relatively low temperatures that exist in the SCWO process (400 - 650{degrees}C) relative to that of air incineration processes (typically 900 - 1300{degrees}C). Oxidation in supercritical water is thus an appealing means of destroying toxic organic compounds while simultaneously separating out undesired inorganics by precipitation. Applications to decontaminating soils and dilute aqueous wastes are of special interest. Earlier work has demonstrated high destruction efficiencies for various organics in SCWO.

  15. Structural Properties and Dynamics of Thiophene in Sub/Supercritical Carbon Dioxide from Car-Parrinello Molecular Dynamics Simulations.

    PubMed

    Zeng, Yongping; Wang, Chunfeng; Xu, Yueyang; Xu, WenLin; Ju, Shengui

    2015-07-01

    Structrual and dynamic properties of thiophene (C4H4S) in supercritical carbon dioxide were studied using Car-Parrinello molecular dynamics simulations. The geometries and energies optimized for the thiophene-CO2 complex show a stable C-H···O hydrogen bond interactions both in gas phase and in supercritical CO2. The radial distribution functions of CO2 around thiophene in the supercritical phase state show a correlation suggesting C-H···O hydrogen bond and S···C interaction. Local structural properties of the mixtures were investigated by angular-radial distributions and spatial distribution functions. The results show a mutually parallel arrangement between the thiophene plane and CO2 molecules at short distances and a high probability of the thiophene being located in the radial directions of the CO2 molecules. The decay of orientational correlations at 318.15 K shows slower relaxation compared to those of 298.15 K for first and second rank correlations. The vibrations of CO2 and thiophene molecules have been examined through an analysis of the velocity autocorrelation functions of the atoms. The C-H stretching modes of thiophene in the isolated configuration are less red-shifted and have a much narrower frequency range than that in the mixtures. PMID:26087291

  16. Hydrodynamic analysis and calculation of metal temperature distribution in spiral water wall of ultra supercritical tower boiler

    NASA Astrophysics Data System (ADS)

    Shen, Chengwu; Yang, Dong; Yao, Danhua; Zhu, Yufeng; Xu, Xueyuan

    2013-07-01

    In this paper, the spiral water wall system of a 1000MW ultra supercritical tower boiler is simplified as a network system, consisting of circuits, pressure grids and connecting tubes. The establishment of the mathematical model for calculating the mass flux distribution and metal temperature in water wall is based on the mass, momentum and energy conservation equations. The water wall flow distribution and temperature profile of the boiler were computed. The result shows that the differences of outlet temperature and mass flux are small in spiral tube water wall at BMCR, 75%BMCR load and 40%BMCR load. The metal temperatures are all in the allowable ranger.

  17. The Effect of Supercritical Water on Microcrack Generation and Crack Healing in the Quartz Constituent of Granite

    NASA Astrophysics Data System (ADS)

    Fujii, Y.; Tanifuji, K.; Takahashi, T.; Stafford, C. E.; Hashida, T.

    2001-12-01

    Supercritical water has properties intermediate between those of gaseous water and liquid water. The density and viscosity of supercritical water is less and diffusivity is greater than that of liquid water. These properties are of great significance when considering the potential development of a supercritical deep-seated geothermal reservoir, where the natural fracture network and permeability may be restricted. We report on experiments that have investigated intragranular microcrack generation and microcrack healing in the quartz constituent of Iidate granite (Fukushima, Japan), at temperature and pressure conditions ranging above and below the supercritical point for water (374 oC/22 MPa), to a maximum of 600 oC and 100 MPa pore fluid pressure. Microstructural data was collated from both permeability experiments and static flow/crack healing experiments conducted in a triaxial cell under isotropic stress conditions, using right cylindrical granite cores saturated in distilled water. The crack healing experiments were performed under a confining pressure of 100 MPa and a constant pore fluid pressure of 50 MPa. The time-dependence of the water/rock interaction, under these conditions, was also determined, with experiments ranging in duration from 0.5 to 96 hours. Permeability experiments were conducted at confining pressures of 20, 25, 50 and 100 MPa. with initial pore fluid pressures approximately 1 MPa higher. Our results show that open crack density increases significantly as both pressure and temperature exceed the critical point for water, with the most significant increases seen at temperatures of 600 oC. All open crack densities show no clear dependence with time. At temperatures of 330 oC, crack healing density increases with both temperature and elapsed time, and increases significantly as the temperature exceeds the critical point for water. However, above temperatures of 450 oC, crack healing density is found to decrease, reaching a low at 550 o

  18. Supercritical water oxidation for the destruction of hazardous waste: better than incineration.

    PubMed

    Al-Duri, Bushra; Alsoqyani, Faihan; Kings, Iain

    2015-12-28

    Supercritical water oxidation (SCWO) is an advanced process mainly employed for the treatment of hazardous stable wastes, otherwise treatable by incineration. It is based on the unique properties of water above its critical point (T(c)=675 K, P(c)=22.2 MPa), making it a superior reaction medium for the destruction of all organics in the presence of oxygen. This work presents preliminary laboratory scale studies on SCWO of nitrogen (N)-containing hazardous hydrocarbons, with a view to enhancing the process performance, using available reagents and non-complex reactor design. This article investigates the destruction of dimethylformamide (DMF), carried out in a continuous (plug flow) reactor system. SCWO of DMF was enhanced by (i) a split-oxidant system, where stoichiometric oxidant was divided between two inlet ports at various ratios and (ii) the addition of isopropyl alcohol (IPA) as a co-fuel, premixed with the feedstock. Testing a range of temperatures, initial DMF concentrations, oxidant ratios, IPA ratios and oxidant split ratios, selected results were presented in terms of % total organic carbon and % N removal. Reaction kinetics were studied and showed a dramatic decrease in the activation energy upon adding IPA. Split-oxidant-feeding enhancement depended on the split ratio and secondary feed position. PMID:26574530

  19. Degradation kinetics of dihydroxyacetone and glyceraldehyde in subcritical and supercritical water

    SciTech Connect

    Kabyemela, B.M.; Adschiri, Tadafumi; Malaluan, R.; Arai, Kunio

    1997-06-01

    Biomass continues to be an important candidate as a renewable resource for energy, chemicals, food, and feedstock. In order to understand the products distribution of cellulose hydrolysis in water, hydrolysis of model compounds of cellulose such as glucose, cellobiose, cellotriose, and cellopentaose is being investigated. One of the important pathways of glucose decomposition was the formation of the C-3 carbon compounds, glyceraldehyde and dihydroxyacetone, which appeared to be isomers and also seemed to have related reaction chemistry. The degradation kinetics of dihydroxyacetone and glyceraldehyde were studied at temperature ranges of 573--673 K, pressures of 25--40 MPa, and residence times from 0.06 to 1.7 s. The reactions of glyceraldehyde gave both dihydroxyacetone and pyruvaldehyde, and yields of dihydroxyacetone were always higher than those of pyruvaldehyde. The reactions of dihydroxyacetone gave glyceraldehyde and pyruvaldehyde, while the yields of pyruvaldehyde were always higher than those of dihydroxyacetone. This pathway involves the reversible isomerization between glyceraldehyde and dihydroxyacetone and their subsequent dehydration to pyruvaldehyde. A model was formulated on the basis of this pathway, and the kinetic rate constants involved were calculated using the experimental results. As the conditions change from subcritical to supercritical, the Arrhenius relationship becomes discontinuous near the critical point of water. At a constant temperature of 673 K, the kinetics constants showed a general increase with an increase in pressure.

  20. Heavy metals stabilization in medical waste incinerator fly ash using alkaline assisted supercritical water technology.

    PubMed

    Jin, Jian; Li, Xiaodong; Chi, Yong; Yan, Jianhua

    2010-12-01

    This study investigated the process of aluminosilicate formation in medical waste incinerator fly ash containing large amounts of heavy metals and treated with alkaline compounds at 375 degrees C and examined how this process affected the mobility and availability of the metals. As a consequence of the treatments, the amount of dissolved heavy metals, and thus their mobility, was greatly reduced, and the metal leaching concentration was below the legislative regulations for metal leachability. Moreover, this process did not produce a high concentration of heavy metals in the effluent. The addition of alkaline compounds such as sodium hydroxide and sodium carbonate can prevent certain heavy metal ions dissolving in water. In comparison with the alkaline-free condition, the extracted concentrations of As, Mn, Pb, Sr and Zn were decreased by about 51.08, 97.22, 58.33, 96.77 and 86.89% by the addition of sodium hydroxide and 66.18, 86.11, 58.33, 83.87 and 81.91% by the addition of sodium carbonate. A mechanism for how the formation of aluminosilicate occurred in supercritical water and affected the mobility and availability of the heavy metals is discussed. The reported results could be useful as basic knowledge for planning new technologies for the hydrothermal stabilization of heavy metals in fly ash. PMID:20430801

  1. Antioxidation Properties and Surface Interactions of Polyvinylpyrrolidone-Capped Zerovalent Copper Nanoparticles Synthesized in Supercritical Water.

    PubMed

    Morioka, Takuya; Takesue, Masafumi; Hayashi, Hiromichi; Watanabe, Masaru; Smith, Richard L

    2016-01-27

    Zerovalent copper nanoparticles (CuNPs) (diameter, 26.5 ± 9 nm) capped with polyvinylpyrrolidone (PVP) were synthesized in supercritical water at 400 °C and 30 MPa with a continuous flow reactor. The PVP-capped CuNPs were dispersed in distilled water, methanol, ethanol, 1-propanol, 2-propanol, butanol, and their mixed solvents to study their long-term stability. Temporal variation of UV-vis spectra and surface plasmon resonance were measured and showed that ethanol, the propanols, and butanol solvents provided varying degrees of oxidative protection for Cu(0). Fourier transform infrared spectroscopy showed that PVP adsorbed onto the surface of the CuNPs with a pyrrolidone ring of PVP even if the CuNPs were oxidized. Intrinsic viscosities of PVP were higher for solvents that provided antioxidation protection than those that give oxidized CuNPs. In solvents that provided Cu(0) with good oxidative protection (ethanol, the propanols, and butanol), PVP polymer chains formed large radii of gyration and coil-like conformations in the solvents so that they were arranged uniformly and orderly on the surface of the CuNPs and could provide protection of the Cu(0) surface against dissolved oxygen. In solvents that provided poor oxidative protection for Cu(0) (water, alcohol-water mixed solvents with 30% water), PVP polymer chains had globular-like conformations due to their relatively high hydrogen-bonding interactions and sparse adsorption onto the CuNP surface. Antioxidative properties of PVP-capped CuNPs in a solvent can be ascribed to the conformation of PVP polymer chains on the Cu(0) particle surface that originates from the interaction between polymer chains and its interaction with the solvent. PMID:26716468

  2. Equilibrium partitioning of 2,4-dichlorophenol between water and near-critical and supercritical carbon dioxide

    SciTech Connect

    Akgerman, A.; Carter, B.D. . Chemical Engineering Dept.)

    1994-07-01

    Distribution coefficients of 2,4-dichlorophenol between supercritical carbon dioxide and water are measured at 298.15 and 319.15 K over the pressure range 11-23 MPa using a single-stage equilibrium cell. The data are modeled by the Peng-Robinson equation of state with modified mixing rules. The data are also compared to literature data on distribution coefficients of phenol and p-chlorophenol.

  3. Oxidation behavior of grain boundary engineered alloy 690 in supercritical water environment

    NASA Astrophysics Data System (ADS)

    Xu, P.; Zhao, L. Y.; Sridharan, K.; Allen, T. R.

    2012-03-01

    Nickel-base alloy is an important structural material that is known for its exceptional high temperature oxidation resistance. Oxidation in this alloy at high temperatures occurs to a greater extent along the grain boundaries. Grain boundary engineering (GBE) was applied to modify the grain boundary characteristics of this alloy to affect its oxidation resistance. Specimens with both low level and high level cold works showed a high fraction of special grain boundaries, and were tested for supercritical water oxidation resistance at 500 °C and 24 MPa. Both GBE and as-received samples exhibited mass gain followed by mass loss during 10 weeks of exposure, but the normalized mass change was small and less than 0.12 mg/cm2. GBE samples showed better oxide layer retention compared to the as-received sample. XRD results indicate that nickel oxide, chromium oxide, and spinel oxide were the three main types of oxides that form on as-received and GBE alloy 690. Three distinct regions were identified on the oxidized surface: a flat region with oxide flakes aligning relatively parallel to the surface, a rough region with polygon-type oxide particles randomly distributed on the surface, and a region with aggregated oxide flakes perpendicular to the surface. The flat region of oxidation consisted of (1 1 1) orientated oxide spinel flakes formed on (1 1 1) oriented alloy 690 grains. The flat oxide region was thinner and showed better oxide adhesion compared to the rough region. Chromium oxidation was found only at random grain boundaries, leading to formation of thick Cr2O3 layer on the surface and chromium depletion underneath. None of this oxidation was found at low angle or special boundaries. The chromium oxidation was attributed to fast chromium diffusion through random boundaries and mechanically deformed regions such as scratches left after polishing. It is envisioned that the oxidation behavior of alloy 690 in supercritical water can be tailored by microstructure

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

    SciTech Connect

    SPRITZER.M; HONG,G

    2005-01-01

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

  5. SAGE 2D and 3D Simulations of the Explosive Venting of Supercritical Fluids Through Porous Media

    NASA Astrophysics Data System (ADS)

    Weaver, R.; Gisler, G.; Svensen, H.; Mazzini, A.

    2008-12-01

    Magmatic intrusive events in large igneous provinces heat sedimentary country rock leading to the eventual release of volatiles. This has been proposed as a contributor to climate change and other environmental impacts. By means of numerical simulations, we examine ways in which these volatiles can be released explosively from depth. Gases and fluids cooked out of country rock by metamorphic heating may be confined for a time by impermeable clays or other barriers, developing high pressures and supercritical fluids. If confinement is suddenly breached (by an earthquake for example) in such a way that the fluid has access to porous sediments, a violent eruption of a non-magmatic mixture of fluid and sediment may result. Surface manifestations of these events could be hydrothermal vent complexes, kimberlite pipes, pockmarks, or mud volcanoes. These are widespread on Earth, especially in large igneous provinces, as in the Karoo Basin of South Africa, the North Sea off the Norwegian margin, and the Siberian Traps. We have performed 2D and 3D simulations with the Sage hydrocode (from Los Alamos and Science Applications International) of supercritical venting in a variety of geometries and configurations. The simulations show several different patterns of propagation and fracturing in porous or otherwise weakened overburden, dependent on depth, source conditions (fluid availability, temperature, and pressure), and manner of confinement breach. Results will be given for a variety of 2D and 3D simulations of these events exploring the release of volatiles into the atmosphere.

  6. Oxidation of phenolics in supercritical water. Combined quarterly technical progress report, December 1, 1995--May 31, 1996

    SciTech Connect

    1996-11-01

    Over the past two quarters, our work has focused on three main areas. The first area of interest involved a reexamination of the rate laws that were formed in past quarters. A possible error was discovered for the analytical methods used in the o-cresol oxidation study and the data were corrected, yielding a new rate equation. The data for hydroxybenzaldehydes were studied again, this time as a system of parallel oxidation and thermolysis reactions. The second area in which progress was made was the study of the thermolysis of nitrophenols and dihydroxybenzenes in supercritical water. These investigations were needed to determine the effect that pyrolysis or hydrolysis had on our previous supercritical water oxidation experiments. Thirdly, we have continued to investigate the use of molecular orbital theory in the determination reactivity indices. A reactivity index, such as the enthalpy of formation, may be used in a structure-reactivity relationship to summarize the kinetics for the oxidation of phenolics in supercritical water. Progress in each of these areas is summarized.

  7. Pressurised hot water extraction with on-line particle formation by supercritical fluid technology.

    PubMed

    Andersson, J M; Lindahl, S; Turner, C; Rodriguez-Meizoso, I

    2012-10-15

    In this work, an on-line process for pressurised hot water extraction (PHWE) of antioxidants from plants as well as drying of the extract in one step by particle formation based on the use of supercritical carbon dioxide (SC-CO(2)) has been developed. This process has been called WEPO®, water extraction and particle formation on-line. With this process, dried extracts from onion with the same composition of quercetin derivatives as non-dried extracts have been obtained as a fine powder with spherical particles from 250 nm to 4 μm in diameter. The major compounds present in the extract were quercetin-3,4'-diglucoside, quercetin-4'-glucoside and quercetin. An auxiliary inert gas (hot N(2)) was used to enhance the drying process. Parameters such as temperature (120 °C), SC-CO(2) and N(2) pressures (80 and 12.5 bar, respectively) and flow rate of SC-CO(2) (10 ml/min), have been settled by trial-and-error in order to achieve a fine and constant spray formation. Water content, size and morphology, antioxidant capacity and quercetin content of the particles were studied to evaluate the efficiency of the WEPO process. Results were compared with the ones from extracts obtained by continuous flow PHWE followed by freeze-drying. Results showed that both processes gave similar results in terms of antioxidant capacity, concentration of quercetin derivatives and water content, while only WEPO was able to produce defined spherical particles smaller than 4 μm. PMID:23442613

  8. Advanced Supercritical Carbon Dioxide Brayton Cycle Development

    SciTech Connect

    Anderson, Mark; Sienicki, James; Moisseytsev, Anton; Nellis, Gregory; Klein, Sanford

    2015-10-21

    Fluids operating in the supercritical state have promising characteristics for future high efficiency power cycles. In order to develop power cycles using supercritical fluids, it is necessary to understand the flow characteristics of fluids under both supercritical and two-phase conditions. In this study, a Computational Fluid Dynamic (CFD) methodology was developed for supercritical fluids flowing through complex geometries. A real fluid property module was implemented to provide properties for different supercritical fluids. However, in each simulation case, there is only one species of fluid. As a result, the fluid property module provides properties for either supercritical CO2 (S-CO2) or supercritical water (SCW). The Homogeneous Equilibrium Model (HEM) was employed to model the two-phase flow. HEM assumes two phases have same velocity, pressure, and temperature, making it only applicable for the dilute dispersed two-phase flow situation. Three example geometries, including orifices, labyrinth seals, and valves, were used to validate this methodology with experimental data. For the first geometry, S-CO2 and SCW flowing through orifices were simulated and compared with experimental data. The maximum difference between the mass flow rate predictions and experimental measurements is less than 5%. This is a significant improvement as previous works can only guarantee 10% error. In this research, several efforts were made to help this improvement. First, an accurate real fluid module was used to provide properties. Second, the upstream condition was determined by pressure and density, which determines supercritical states more precise than using pressure and temperature. For the second geometry, the flow through labyrinth seals was studied. After a successful validation, parametric studies were performed to study geometric effects on the leakage rate. Based on these parametric studies, an optimum design strategy for the see

  9. Effect of ultrasonic impact peening on the corrosion of ferritic-martensitic steels in supercritical water

    NASA Astrophysics Data System (ADS)

    Dong, Ziqiang; Liu, Zhe; Li, Ming; Luo, Jing-Li; Chen, Weixing; Zheng, Wenyue; Guzonas, Dave

    2015-02-01

    Ferritic-Martensitic (F/M) steels are important candidate alloys to be used in the next generation (Generation-IV) SCWRs. In this work, two F/M steels with the same Cr content of around 12 wt.% and varied Si content from 0.6 wt.% to 2.2 wt.% were evaluated in supercritical water (SCW) at 500 °C and 25 MPa for up to 1000 h. The effect of ultrasonic shot peening on the oxidation behavior of these F/M steels have been investigated. The results showed that the oxidation was affected by the Si content as well as the surface modification. The F/M steel with low Si concentration exhibited higher corrosion resistance than that of the alloy with high Si content. Shot peening, which could modify the microstructure at the surface, showed significantly beneficial effect to improving the oxidation resistance. A thin, uniform oxide layer formed on the peened sample could be attributed to the enhanced diffusion of Cr induced by the surface modification.

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

    PubMed

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

    2015-09-01

    To achieve the maximum H2 yield (GYH2), TOC removal rate (TRE) and carbon recovery rate (CR), response surface methodology was applied to optimize the process parameters for supercritical water partial oxidation (SWPO) of landfill leachate in a batch reactor. Quadratic polynomial models for GYH2, CR and TRE were established with Box-Behnken design. GYH2, CR and TRE reached up to 14.32mmol·gTOC(-1), 82.54% and 94.56% under optimum conditions, respectively. TRE was invariably above 91.87%. In contrast, TC removal rate (TR) only changed from 8.76% to 32.98%. Furthermore, carbonate and bicarbonate were the most abundant carbonaceous substances in product, whereas CO2 and H2 were the most abundant gaseous products. As a product of nitrogen-containing organics, NH3 has an important effect on gas composition. The carbon balance cannot be reached duo to the formation of tar and char. CR increased with the increase of temperature and oxidation coefficient. PMID:26028557