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Sample records for air oxidation reactor

  1. Air trichloroethylene oxidation in a corona plasma-catalytic reactor

    NASA Astrophysics Data System (ADS)

    Masoomi-Godarzi, S.; Ranji-Burachaloo, H.; Khodadadi, A. A.; Vesali-Naseh, M.; Mortazavi, Y.

    2014-08-01

    The oxidative decomposition of trichloroethylene (TCE; 300 ppm) by non-thermal corona plasma was investigated in dry air at atmospheric pressure and room temperature, both in the absence and presence of catalysts including MnOx, CoOx. The catalysts were synthesized by a co-precipitation method. The morphology and structure of the catalysts were characterized by BET surface area measurement and Fourier Transform Infrared (FTIR) methods. Decomposition of TCE and distribution of products were evaluated by a gas chromatograph (GC) and an FTIR. In the absence of the catalyst, TCE removal is increased with increases in the applied voltage and current intensity. Higher TCE removal and CO2 selectivity is observed in presence of the corona and catalysts, as compared to those with the plasma alone. The results show that MnOx and CoOx catalysts can dissociate the in-plasma produced ozone to oxygen radicals, which enhances the TCE decomposition.

  2. Surface-catalyzed air oxidation reactions of hydrazines: Tubular reactor studies

    NASA Technical Reports Server (NTRS)

    Kilduff, Jan E.; Davis, Dennis D.; Koontz, Steven L.

    1988-01-01

    The surface-catalyzed air oxidation reactions of hydrazine, monomethylhydrazine, unsymmetrical dimethylhydrazine, symmetrical dimethylhydrazine, trimethylhydrazine and tetramethylhydrazine were investigated in a metal-powder packed turbular flow reactor at 55 plus or minus 3 C. Hydrazine was completely reacted on all surfaces studied. The major products of monomethylhydrazine (MMH) oxidation were methanol, methane and methyldiazene. The di-, tri- and tetra-methyl hydrazines were essentially unreactive under these conditions. The relative catalytic reactivities toward MMH are: Fe greater than Al2O3 greater than Ti greater than Zn greater than 316 SS greater than Cr greater than Ni greater than Al greater than 304L SS. A kinetic scheme and mechanism involving adsorption, oxidative dehydrogenation and reductive elimination reactions on a metal oxide surface are proposed.

  3. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    NASA Astrophysics Data System (ADS)

    Palm, B. B.; Campuzano-Jost, P.; Ortega, A. M.; Day, D. A.; Kaser, L.; Jud, W.; Karl, T.; Hansel, A.; Hunter, J. F.; Cross, E. S.; Kroll, J. H.; Peng, Z.; Brune, W. H.; Jimenez, J. L.

    2015-11-01

    Ambient air was oxidized by OH radicals in an oxidation flow reactor (OFR) located in a montane pine forest during the BEACHON-RoMBAS campaign to study biogenic secondary organic aerosol (SOA) formation and aging. High OH concentrations and short residence times allowed for semi-continuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative time scales of condensation of low volatility organic compounds (LVOCs) onto particles, condensational loss to the walls, and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 4 μg m-3 when LVOC fate corrected) compared to daytime (average 1 μg m-3 when LVOC fate corrected), with maximum formation observed at 0.4-1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene + p-cymene concentrations, including a substantial increase just after sunrise at 07:00 LT. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of small oxidized organic compounds, and net production at lower ages followed by net consumption of terpenoid oxidation products as photochemical age increased. New particle formation was observed in the reactor after oxidation, especially during times when precursor gas concentrations and SOA formation were largest. Approximately 6 times more SOA was formed in the reactor from OH oxidation than

  4. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    NASA Astrophysics Data System (ADS)

    Palm, Brett B.; Campuzano-Jost, Pedro; Ortega, Amber M.; Day, Douglas A.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Hunter, James F.; Cross, Eben S.; Kroll, Jesse H.; Peng, Zhe; Brune, William H.; Jimenez, Jose L.

    2016-03-01

    An oxidation flow reactor (OFR) is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen-Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed for semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs) onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m-3 when LVOC fate corrected) compared to daytime (average 0.9 µg m-3 when LVOC fate corrected), with maximum formation observed at 0.4-1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of small oxidized organic

  5. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    DOE PAGESBeta

    Palm, Brett B.; Campuzano-Jost, Pedro; Ortega, Amber M.; Day, Douglas A.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Hunter, James F.; Cross, Eben S.; et al

    2016-03-08

    An oxidation flow reactor (OFR) is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen–Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed formore » semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs) onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m–3 when LVOC fate corrected) compared to daytime (average 0.9 µg m–3 when LVOC fate corrected), with maximum formation observed at 0.4–1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (>10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of small

  6. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    DOE PAGESBeta

    Palm, Brett B.; Campuzano-Jost, Pedro; Ortega, Amber M.; Day, Douglas A.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Hunter, James F.; Cross, Eben S.; et al

    2016-03-08

    An oxidation flow reactor (OFR) is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen–Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed formore » semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs) onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m−3 when LVOC fate corrected) compared to daytime (average 0.9 µg m−3 when LVOC fate corrected), with maximum formation observed at 0.4–1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of

  7. In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

    SciTech Connect

    Palm, Brett B.; Campuzano-Jost, Pedro; Ortega, Amber M.; Day, Douglas A.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Hunter, James F.; Cross, Eben S.; Kroll, Jesse H.; Peng, Zhe; Brune, William H.; Jimenez, Jose L.

    2016-01-01

    An oxidation flow reactor (OFR) is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen–Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed for semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs) onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m−3 when LVOC fate corrected) compared to daytime (average 0.9 µg m−3 when LVOC fate corrected), with maximum formation observed at 0.4–1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the

  8. Secondary Organic Aerosol Formation from Ambient Air in an Oxidation Flow Reactor at GoAmazon2014/5

    NASA Astrophysics Data System (ADS)

    Palm, Brett B.; de Sa, Suzane S.; Campuzano-Jost, Pedro; Day, Douglas A.; Hu, Weiwei; Seco, Roger; Park, Jeong-Hoo; Guenther, Alex; Kim, Saewung; Brito, Joel; Wurm, Florian; Artaxo, Paulo; Yee, Lindsay; Isaacman-VanWertz, Gabrial; Goldstein, Allen; Newburn, Matt K.; Lizabeth Alexander, M.; Martin, Scot T.; Brune, William H.; Jimenez, Jose L.

    2016-04-01

    During GoAmazon2014/5, ambient air was exposed to controlled concentrations of OH or O3 in situ using an oxidation flow reactor (OFR). Oxidation ranged from hours-several weeks of aging. Oxidized air was sampled by several instruments (e.g., HR-AMS, ACSM, PTR-TOF-MS, SMPS, CCN) at both the T3 site (IOP1: Feb 1-Mar 31, 2014, and IOP2: Aug 15-Oct 15, 2014) and T2 site (between IOPs and into 2nd IOP). The oxidation of ambient air in the OFR led to substantial and variable secondary organic aerosol (SOA) formation from any SOA-precursor gases, known and unknown, that entered the OFR. In general, more SOA was produced during the nighttime than daytime, suggesting that SOA-precursor gases were found in relatively higher concentrations at night. Similarly, more SOA was formed in the dry season (IOP2) than wet season (IOP1). The maximum amount of SOA produced during nighttime from OH oxidation ranged from less than 1 μg/m3 on some nights to greater than 10 μg/m3 on other nights. O3 oxidation of ambient air also led to SOA formation, although several times less than from OH oxidation. The amount of SOA formation sometimes, but not always, correlated with measured gas-phase biogenic and/or anthropogenic SOA precursors (e.g., SV-TAG sesquiterpenes, PTR-TOFMS aromatics, isoprene, and monoterpenes). The SOA mass formed in the OFR from OH oxidation was up to an order of magnitude larger than could be explained from aerosol yields of measured primary VOCs. This along with measurements from previous campaigns suggests that most SOA was formed from intermediate S/IVOC sources (e.g., VOC oxidation products, evaporated POA, or direct emissions). To verify the SOA yields of VOCs under OFR experimental conditions, atmospherically-relevant concentrations of several VOCs were added individually into ambient air in the OFR and oxidized by OH or O3. SOA yields in the OFR were similar to published chamber yields. Preliminary PMF factor analysis showed production of secondary factors in

  9. Stabilized three-stage oxidation of DME/air mixture in a micro flow reactor with a controlled temperature profile

    SciTech Connect

    Oshibe, Hiroshi; Nakamura, Hisashi; Tezuka, Takuya; Hasegawa, Susumu; Maruta, Kaoru

    2010-08-15

    Ignition and combustion characteristics of a stoichiometric dimethyl ether (DME)/air mixture in a micro flow reactor with a controlled temperature profile which was smoothly ramped from room temperature to ignition temperature were investigated. Special attention was paid to the multi-stage oxidation in low temperature condition. Normal stable flames in a mixture flow in the high velocity region, and non-stationary pulsating flames and/or repetitive extinction and ignition (FREI) in the medium velocity region were experimentally confirmed as expected from our previous study on a methane/air mixture. In addition, stable double weak flames were observed in the low velocity region for the present DME/air mixture case. It is the first observation of stable double flames by the present methodology. Gas sampling was conducted to obtain major species distributions in the flow reactor. The results indicated that existence of low-temperature oxidation was conjectured by the production of CH{sub 2}O occured in the upstream side of the experimental first luminous flame, while no chemiluminescence from it was seen. One-dimensional computation with detailed chemistry and transport was conducted. At low mixture velocities, three-stage oxidation was confirmed from profiles of the heat release rate and major chemical species, which was broadly in agreement with the experimental results. Since the present micro flow reactor with a controlled temperature profile successfully presented the multi-stage oxidations as spatially separated flames, it is shown that this flow reactor can be utilized as a methodology to separate sets of reactions, even for other practical fuels, at different temperature. (author)

  10. Wet air oxidation for the treatment of industrial wastes. Chemical aspects, reactor design and industrial applications in Europe

    SciTech Connect

    Debellefontaine, H.; Foussard, J.N.

    2000-07-01

    Aqueous wastes containing organic pollutants can be efficiently treated by wet air oxidation (WAO), i.e., oxidation (or combustion) by molecular oxygen in the liquid phase, at high temperature (200--325 C) and pressure (up to 175 bar). This method is suited to the elimination of special aqueous wastes from the chemical industry as well as to the treatment of domestic sludge. It is an enclosed process, with a limited interaction with the environment, as opposed to incineration. Usually, the operating cost is lower than 95 Euro M{sup {minus}3} and the preferred COD load ranges from 10 to 80 kg m{sup {minus}3}. Only a handful of industrial reactors are in operation world-wide, mainly because of the high capital investment they require. This paper reviews the major results obtained with the WAO process and assess its field of possible application to industrial wastes. In addition, as only a very few studies have been devoted to the scientific design of such reactors (bubble columns), what needs to be known for this scientific design is discussed. At present, a computer program aimed at determining the performance of a wet air oxidation reactor depending on the various operating parameters has been implemented at the laboratory. Some typical results are presented, pointing out the most important parameters and the specific behavior of these units.

  11. Air oxidation behavior of fuel for the High Temperature Engineering Test Reactor (HTTR)

    NASA Astrophysics Data System (ADS)

    Kikuchi, Hironobu; Hayashi, Kimio; Fukuda, Kousaku

    1992-08-01

    The oxidation behavior of the HTTR fuel was studied with respect to the scenario of an air ingress accident which had been assessed in the HTTR safety analysis. The coated fuel particles were heated under a sufficient air flow in the temperature range of 900-1400 C for maximum duration of 600 h (at 1300 C). Failure fractions of the SiC coating layer after the heat treatments remained within the fraction at the fuel production. And the failure behavior of the SiC layer did not depend on such heating conditions as the temperature and the duration in the present experiment. It was confirmed by scanning electron microscopy (SEM), X-ray diffraction, and laser Raman spectroscopy that a thin oxide film was formed on the SiC layer by the heat treatments.

  12. AIR COOLED NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1958-05-27

    A nuclear reactor of the air-cooled, graphite moderated type is described. The active core consists of a cubicle mass of graphite, approximately 25 feet in each dimension, having horizontal channels of square cross section extending between two of the opposite faces, a plurality of cylindrical uranium slugs disposed in end to end abutting relationship within said channels providing a space in the channels through which air may be circulated, and a cadmium control rod extending within a channel provided in the moderator. Suitable shielding is provlded around the core, as are also provided a fuel element loading and discharge means, and a means to circulate air through the coolant channels through the fuel charels to cool the reactor.

  13. Looking North at Reactor Number One and Air Vent on ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking North at Reactor Number One and Air Vent on Fourth Floor of Oxide Building - Hematite Fuel Fabrication Facility, Oxide Building & Oxide Loading Dock, 3300 State Road P, Festus, Jefferson County, MO

  14. Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area

    NASA Astrophysics Data System (ADS)

    Ortega, A. M.; Hayes, P. L.; Peng, Z.; Palm, B. B.; Hu, W.; Day, D. A.; Li, R.; Cubison, M. J.; Brune, W. H.; Graus, M.; Warneke, C.; Gilman, J. B.; Kuster, W. C.; de Gouw, J. A.; Jimenez, J. L.

    2015-08-01

    Field studies in polluted areas over the last decade have observed large formation of secondary organic aerosol (SOA) that is often poorly captured by models. The study of SOA formation using ambient data is often confounded by the effects of advection, vertical mixing, emissions, and variable degrees of photochemical aging. An Oxidation Flow Reactor (OFR) was deployed to study SOA formation in real-time during the CalNex campaign in Pasadena, CA, in 2010. A high-resolution aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS) alternated sampling ambient and reactor-aged air. The reactor produced OH concentrations up to 4 orders of magnitude higher than in ambient air, achieving equivalent atmospheric aging from hours up to several weeks in 3 min of processing. OH radical concentration was continuously stepped, obtaining measurements of real-time SOA formation and oxidation at multiple equivalent ages from 0.8 days-6.4 weeks. Enhancement of OA from aging showed a maximum net SOA production between 0.8-6 days of aging with net OA mass loss beyond 2 weeks. Reactor SOA mass peaked at night, in the absence of ambient photochemistry, and correlated with trimethylbenzene concentrations. Reactor SOA formation was inversely correlated with ambient SOA and Ox, which along with the short-lived VOC correlation, indicates the importance of relatively reactive (τOH ∼ 0.3 day) SOA precursors in the LA-Basin. Evolution of the elemental composition in the reactor was similar to trends observed in the atmosphere (O : C vs. H : C slope ∼ -0.65). Oxidation state of carbon (OSC) in reactor SOA increased steeply with age and remained elevated (OSC ∼ 2) at the highest photochemical ages probed. The ratio of OA in the reactor output to excess CO (ΔCO, ambient CO above regional background) vs. photochemical age is similar to previous studies at low to moderate ages and also extends to higher ages where OA loss dominates. The mass added at low

  15. Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area

    DOE PAGESBeta

    Ortega, Amber M.; Hayes, Patrick L.; Peng, Zhe; Palm, Brett B.; Hu, Weiwei; Day, Douglas A.; Li, Rui; Cubison, Michael J.; Brune, William H.; Graus, Martin; et al

    2016-06-15

    Field studies in polluted areas over the last decade have observed large formation of secondary organic aerosol (SOA) that is often poorly captured by models. The study of SOA formation using ambient data is often confounded by the effects of advection, vertical mixing, emissions, and variable degrees of photochemical aging. An oxidation flow reactor (OFR) was deployed to study SOA formation in real-time during the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign in Pasadena, CA, in 2010. A high-resolution aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS) alternated sampling ambient andmore » reactor-aged air. The reactor produced OH concentrations up to 4 orders of magnitude higher than in ambient air. OH radical concentration was continuously stepped, achieving equivalent atmospheric aging of 0.8 days–6.4 weeks in 3 min of processing every 2 h. Enhancement of organic aerosol (OA) from aging showed a maximum net SOA production between 0.8–6 days of aging with net OA mass loss beyond 2 weeks. Reactor SOA mass peaked at night, in the absence of ambient photochemistry and correlated with trimethylbenzene concentrations. Reactor SOA formation was inversely correlated with ambient SOA and Ox, which along with the short-lived volatile organic compound correlation, indicates the importance of very reactive (τOH ~ 0.3 day) SOA precursors (most likely semivolatile and intermediate volatility species, S/IVOCs) in the Greater Los Angeles Area. Evolution of the elemental composition in the reactor was similar to trends observed in the atmosphere (O : C vs. H : C slope ~ –0.65). Oxidation state of carbon (OSc) in reactor SOA increased steeply with age and remained elevated (OSC ~ 2) at the highest photochemical ages probed. The ratio of OA in the reactor output to excess CO (ΔCO, ambient CO above regional background) vs. photochemical age is similar to previous studies at low to moderate ages and

  16. Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area

    NASA Astrophysics Data System (ADS)

    Ortega, Amber M.; Hayes, Patrick L.; Peng, Zhe; Palm, Brett B.; Hu, Weiwei; Day, Douglas A.; Li, Rui; Cubison, Michael J.; Brune, William H.; Graus, Martin; Warneke, Carsten; Gilman, Jessica B.; Kuster, William C.; de Gouw, Joost; Gutiérrez-Montes, Cándido; Jimenez, Jose L.

    2016-06-01

    Field studies in polluted areas over the last decade have observed large formation of secondary organic aerosol (SOA) that is often poorly captured by models. The study of SOA formation using ambient data is often confounded by the effects of advection, vertical mixing, emissions, and variable degrees of photochemical aging. An oxidation flow reactor (OFR) was deployed to study SOA formation in real-time during the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign in Pasadena, CA, in 2010. A high-resolution aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS) alternated sampling ambient and reactor-aged air. The reactor produced OH concentrations up to 4 orders of magnitude higher than in ambient air. OH radical concentration was continuously stepped, achieving equivalent atmospheric aging of 0.8 days-6.4 weeks in 3 min of processing every 2 h. Enhancement of organic aerosol (OA) from aging showed a maximum net SOA production between 0.8-6 days of aging with net OA mass loss beyond 2 weeks. Reactor SOA mass peaked at night, in the absence of ambient photochemistry and correlated with trimethylbenzene concentrations. Reactor SOA formation was inversely correlated with ambient SOA and Ox, which along with the short-lived volatile organic compound correlation, indicates the importance of very reactive (τOH ˜ 0.3 day) SOA precursors (most likely semivolatile and intermediate volatility species, S/IVOCs) in the Greater Los Angeles Area. Evolution of the elemental composition in the reactor was similar to trends observed in the atmosphere (O : C vs. H : C slope ˜ -0.65). Oxidation state of carbon (OSc) in reactor SOA increased steeply with age and remained elevated (OSC ˜ 2) at the highest photochemical ages probed. The ratio of OA in the reactor output to excess CO (ΔCO, ambient CO above regional background) vs. photochemical age is similar to previous studies at low to moderate ages and also extends to

  17. An Innovative Reactor Technology to Improve Indoor Air Quality

    SciTech Connect

    Rempel, Jane

    2013-03-30

    As residential buildings achieve tighter envelopes in order to minimize energy used for space heating and cooling, accumulation of indoor air pollutants such as volatile organic compounds (VOCs), becomes a major concern causing poor air quality and increased health risks. Current VOC removal methods include sorbents, ultraviolet photocatalytic oxidation (UVPCO), and increased ventilation, but these methods do not capture or destroy all VOCs or are prohibitively expensive to implement. TIAX's objective in this program was to develop a new VOC removal technology for residential buildings. This novel air purification technology is based on an innovative reactor and light source design along with UVPCO properties of the chosen catalyst to purify indoor air and enhance indoor air quality (IAQ). During the program we designed, fabricated and tested a prototype air purifier to demonstrate its feasibility and effectiveness. We also measured kinetics of VOC destruction on photocatalysts, providing deep insight into reactor design.

  18. Solid oxide electrochemical reactor science.

    SciTech Connect

    Sullivan, Neal P.; Stechel, Ellen Beth; Moyer, Connor J.; Ambrosini, Andrea; Key, Robert J.

    2010-09-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

  19. Looking Northeast in Oxide Building at Reactors on Second Floor ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking Northeast in Oxide Building at Reactors on Second Floor Including Reactor One (Left) and Reactor Two (Right) - Hematite Fuel Fabrication Facility, Oxide Building & Oxide Loading Dock, 3300 State Road P, Festus, Jefferson County, MO

  20. Nuclear reactor shield including magnesium oxide

    DOEpatents

    Rouse, Carl A.; Simnad, Massoud T.

    1981-01-01

    An improvement in nuclear reactor shielding of a type used in reactor applications involving significant amounts of fast neutron flux, the reactor shielding including means providing structural support, neutron moderator material, neutron absorber material and other components as described below, wherein at least a portion of the neutron moderator material is magnesium in the form of magnesium oxide either alone or in combination with other moderator materials such as graphite and iron.

  1. Ammonia oxidizing bacteria and archaea in horizontal flow biofilm reactors treating ammonia-contaminated air at 10 °C.

    PubMed

    Gerrity, Seán; Clifford, Eoghan; Kennelly, Colm; Collins, Gavin

    2016-05-01

    The objective of this study was to demonstrate the feasibility of novel, Horizontal Flow Biofilm Reactor (HFBR) technology for the treatment of ammonia (NH3)-contaminated airstreams. Three laboratory-scale HFBRs were used for remediation of an NH3-containing airstream at 10 °C during a 90-d trial to test the efficacy of low-temperature treatment. Average ammonia removal efficiencies of 99.7 % were achieved at maximum loading rates of 4.8 g NH3 m(3) h(-1). Biological nitrification of ammonia to nitrite (NO2 (-)) and nitrate (NO3 (-)) was mediated by nitrifying bacterial and archaeal biofilm populations. Ammonia-oxidising bacteria (AOB) were significantly more abundant than ammonia-oxidising archaea (AOA) vertically at each of seven sampling zones along the vertical HFBRs. Nitrosomonas and Nitrosospira, were the two most dominant bacterial genera detected in the HFBRs, while an uncultured archaeal clone dominated the AOA community. The bacterial community composition across the three HFBRs was highly conserved, although variations occurred between HFBR zones and were driven by physicochemical variables. The study demonstrates the feasibility of HFBRs for the treatment of ammonia-contaminated airstreams at low temperatures; identifies key nitrifying microorganisms driving the removal process; and provides insights for process optimisation and control. The findings are significant for industrial applications of gas oxidation technology in temperate climates. PMID:26879980

  2. Staged membrane oxidation reactor system

    DOEpatents

    Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

    2014-05-20

    Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

  3. Staged membrane oxidation reactor system

    DOEpatents

    Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

    2013-04-16

    Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

  4. Staged membrane oxidation reactor system

    DOEpatents

    Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

    2012-09-11

    Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

  5. Multi-stage, isothermal CO preferential oxidation reactor

    DOEpatents

    Skala, Glenn William; Brundage, Mark A.; Borup, Rodney Lynn; Pettit, William Henry; Stukey, Kevin; Hart-Predmore, David James; Fairchok, Joel

    2000-01-01

    A multi-stage, isothermal, carbon monoxide preferential oxidation (PrOx) reactor comprising a plurality of serially arranged, catalyzed heat exchangers, each separated from the next by a mixing chamber for homogenizing the gases exiting one heat exchanger and entering the next. In a preferred embodiment, at least some of the air used in the PrOx reaction is injected directly into the mixing chamber between the catalyzed heat exchangers.

  6. DESTRUCTION OF AIR EMISSIONS USING CATALYTIC OXIDATION

    EPA Science Inventory

    The paper discusses key emission stream characteristics and hazardous air pollutant (HAP) characteristics that affect the applicability of catalytic oxidation as an air pollution control technique in which volatile organic compounds (VOCs) and vapor-phase air toxics in an air emi...

  7. Prototypical experiments relating to air oxidation of Zircaloy-4 at high temperatures

    NASA Astrophysics Data System (ADS)

    Steinbrück, Martin

    2009-08-01

    The mechanism of the reaction between Zircaloy-4 and air at temperatures from 800 to 1500 °C was studied. Air attack under prototypical conditions with air ingress during a hypothetic severe nuclear reactor accident was investigated. Oxidation in air and in air and nitrogen-containing atmospheres leads to a major degradation of the cladding material. The main mechanism is the formation of zirconium nitride and its re-oxidation. Pre-oxidation in steam prevents air attack as long as the oxide scale is intact. Under steam/oxygen starvation conditions, the oxide scale is reduced and significant external nitride formation takes place. When modeling air ingress in severe accident computer codes, parabolic correlations for oxidation in air may be applied only for high temperatures (>1400 °C) and for pre-oxidized cladding (⩾1100 °C). Under all other conditions, faster, rather linear reaction kinetics should be applied.

  8. Soot oxidation in a corona plasma-catalytic reactor

    NASA Astrophysics Data System (ADS)

    Ranji-Burachaloo, H.; Masoomi-Godarzi, S.; Khodadadi, A. A.; Vesali-Naseh, M.; Mortazavi, Y.

    2014-08-01

    Oxidation of soot by corona plasma was investigated at conditions of exhaust gases from diesel engines, both in the absence and presence of CoOx as a catalyst. The CoOx catalyst nanoparticles were synthesized by a precipitation method. The BET surface area of the catalyst was 50 m2/g, corresponding to 23 nm particles. An aluminum grid was sequentially dip-coated for several times by suspensions of the soot in toluene and/or fine catalyst powder in DI water. The grid was used as the plate of a pin-to-plate corona reactor. Air at 180 °C was passed through the corona reactor to oxidize the soot, oxidation products of which were analyzed by both gas chromatograph and FTIR with a gas cell. Soot oxidation rate linearly increased with an increase of input energy. When the soot was deposited on a layer of the CoOx catalyst, the soot oxidation rate increased up to 2 times. The only product of the plasma (catalytic) oxidation of soot was CO2 determined by FTIR. O produced in the plasma discharge oxidized the soot and the active surface oxygen enhanced its rate.

  9. Ozone/Ultraviolet-Photo-Oxidation Reactor

    NASA Technical Reports Server (NTRS)

    Swartz, Ari Ben; Agthe, Richard E.

    1989-01-01

    Experimental chemical-processing system destroys waste hydrazine in water by use of ozone in ultraviolet-photo-oxidation reactor. New process reduces concentrations of hydrazines and intermediate decomposition products in effluent liquid and gas to below limit of detectability. Liquid sprayed in reaction chamber past ultraviolet lamps, against flow of oxygen and ozone. Hydrazines and intermediate decomposition products oxidized to harmless substances. Effectiveness and speed of process depends on maintenance of circulating liquid at correct pH, determines lower limit of oxidation by ozone.

  10. AIR DUCTS STAND NEXT TO (AND OUTSIDE OF) REACTOR CABINET ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    AIR DUCTS STAND NEXT TO (AND OUTSIDE OF) REACTOR CABINET AT THE SOUTHWEST AND NORTHEAST CORNERS OF THE REACTOR'S THERMAL SHIELD. THEY WILL BE ENVELOPED IN BIOLOGICAL CONCRETE SHIELD. IN THE SUB-BASEMENT, THE TWO DUCTS WILL JOIN TOGETHER AND EXIT THE BUILDING TO THE FAN HOUSE. CAMERA FACING NORTH. INL NEGATIVE NO. 1625. Unknown Photographer, 3/6/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  11. Hypothetical air ingress scenarios in advanced modular high temperature gas cooled reactors

    SciTech Connect

    Kroeger, P.G.

    1988-01-01

    Considering an extremely hypothetical scenario of complete cross duct failure and unlimited air supply into the reactor vessel of a modular high temperature gas cooled ractor, it is found that the potential air inflow remains limited due to the high friction pressure drop through the active core. All incoming air will be oxidized to CO and some local external burning would be temporarily possible in such a scenario. The accident would have to continue with unlimited air supply for hundreds of hours before the core structural integrity would be jeopardized.

  12. 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.

  13. 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.

  14. 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.

  15. Oxidation and Volatilization from Tantalum Alloy During Air Exposure

    SciTech Connect

    Smolik, Galen Richard; Petti, David Andrew; Schuetz, Stanley Thomas

    2000-10-01

    Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but are oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200 degrees C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before the formation of an oxide scale impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m2-h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices.

  16. Catalytic Reactor For Oxidizing Mercury Vapor

    DOEpatents

    Helfritch, Dennis J.

    1998-07-28

    A catalytic reactor (10) for oxidizing elemental mercury contained in flue gas is provided. The catalyst reactor (10) comprises within a flue gas conduit a perforated corona discharge plate (30a, b) having a plurality of through openings (33) and a plurality of projecting corona discharge electrodes (31); a perforated electrode plate (40a, b, c) having a plurality of through openings (43) axially aligned with the through openings (33) of the perforated corona discharge plate (30a, b) displaced from and opposing the tips of the corona discharge electrodes (31); and a catalyst member (60a, b, c, d) overlaying that face of the perforated electrode plate (40a, b, c) opposing the tips of the corona discharge electrodes (31). A uniformly distributed corona discharge plasma (1000) is intermittently generated between the plurality of corona discharge electrode tips (31) and the catalyst member (60a, b, c, d) when a stream of flue gas is passed through the conduit. During those periods when corona discharge (1000) is not being generated, the catalyst molecules of the catalyst member (60a, b, c, d) adsorb mercury vapor contained in the passing flue gas. During those periods when corona discharge (1000) is being generated, ions and active radicals contained in the generated corona discharge plasma (1000) desorb the mercury from the catalyst molecules of the catalyst member (60a, b, c, d), oxidizing the mercury in virtually simultaneous manner. The desorption process regenerates and activates the catalyst member molecules.

  17. Kinetics and fixed-bed reactor modeling of butane oxidation to maleic anhydride

    SciTech Connect

    Sharma, R.K.; Cresswell, D.L. ); Newson, E.J. )

    1991-01-01

    This paper reports on selective oxidation kinetics of n-butane to maleic anhydride in air studied over a commercial, fixed-bed vanadium-phosphor oxide catalyst. The temperature range was 573-653 K with butane concentrations up to 3 mol % in the feed, which is within flammability limits but below ignition temperatures. The rate data were modeled using power law kinetics with product inhibition and included total oxidation and decomposition reactions. Kinetic parameters were estimated using a multiresponse, nonlinear regression algorithm showing intercorrelation effects. The kinetics were combined with independent measurements of catalyst diffusivity and reactor heat transfer using a one- dimensional heterogeneous reactor model.

  18. Implementation of model predictive control on a hydrothermal oxidation reactor

    SciTech Connect

    Muske, K.R.; Dell`Orco, P.C.; Le, L.A.; Flesner, R.L.

    1998-12-31

    This paper describes the model-based control algorithm developed for a hydrothermal oxidation reactor at the Pantex Department of Energy facility in Amarillo, Texas. The combination of base hydrolysis and hydrothermal oxidation is used for the disposal of PBX 9404 high explosive at Pantex. The reactor oxidizes the organic compounds in the hydrolysate solutions obtained from the base hydrolysis process. The objective of the model predictive controller is to minimize the total aqueous nitrogen compounds in the effluent of the reactor. The controller also maintains a desired excess oxygen concentration in the reactor effluent to ensure the complete destruction of the organic carbon compounds in the hydrolysate.

  19. WET OXIDATION OF MUNICIPAL SLUDGE BY THE VERTICAL TUBE REACTOR

    EPA Science Inventory

    A study was undertaken to assess the feasibility of carrying out oxidation of dilute sewage sludge by means of the vertical tube reactor (VTR) system. A pilot scale facility along with a laboratory reactor were used for this study. Dilute sewage sludge was oxidized in the laborat...

  20. Storage of LWR (light-water-reactor) spent fuel in air

    SciTech Connect

    Thomas, L.E.; Charlot, L.A.; Coleman, J.E. ); Knoll, R.W. )

    1989-12-01

    An experimental program is being conducted at Pacific Northwest Laboratory (PNL) to determine the oxidation response of light-water-reactor (LWR) spent fuels under conditions appropriate to fuel storage in air. The program is designed to investigate several independent variables that might affect the oxidation behavior of spent fuel. Included are temperature (135 to 230{degree}C), fuel burnup (to about 34 MWd/kgM), reactor type (pressurized and boiling water reactors), moisture level in the air, and the presence of a high gamma field. In continuing tests with declad spent fuel and nonirradiated UO{sub 2} specimens, oxidation rates were monitored by weight-gain measurements and the microstructures of subsamples taken during the weighing intervals were characterized by several analytical methods. The oxidation behavior indicated by weight gain and time to form powder will be reported in Volume III of this series. The characterization results obtained from x-ray diffractometry, transmission electron microscopy, scanning electron microscopy, and Auger electron spectrometry of oxidized fuel samples are presented in this report. 28 refs., 21 figs., 3 tabs.

  1. Liquid metal reactor air cooling baffle

    DOEpatents

    Hunsbedt, A.

    1994-08-16

    A baffle is provided between a relatively hot containment vessel and a relatively cold silo for enhancing air cooling performance. The baffle includes a perforate inner wall positionable outside the containment vessel to define an inner flow riser therebetween, and an imperforate outer wall positionable outside the inner wall to define an outer flow riser therebetween. Apertures in the inner wall allow thermal radiation to pass laterally therethrough to the outer wall, with cooling air flowing upwardly through the inner and outer risers for removing heat. 3 figs.

  2. STUDY ON AIR INGRESS MITIGATION METHODS IN THE VERY HIGH TEMPERATURE GAS COOLED REACTOR (VHTR)

    SciTech Connect

    Chang H. Oh

    2011-03-01

    An air-ingress accident followed by a pipe break is considered as a critical event for a very high temperature gas-cooled reactor (VHTR). Following helium depressurization, it is anticipated that unless countermeasures are taken, air will enter the core through the break leading to oxidation of the in-core graphite structure. Thus, without mitigation features, this accident might lead to severe exothermic chemical reactions of graphite and oxygen. Under extreme circumstances, a loss of core structural integrity may occur along with excessive release of radiological inventory. Idaho National Laboratory under the auspices of the U.S. Department of Energy is performing research and development (R&D) that focuses on key phenomena important during challenging scenarios that may occur in the VHTR. Phenomena Identification and Ranking Table (PIRT) studies to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important (Oh et al. 2006, Schultz et al. 2006). Consequently, the development of advanced air ingress-related models and verification and validation (V&V) requirements are part of the experimental validation plan. This paper discusses about various air-ingress mitigation concepts applicable for the VHTRs. The study begins with identifying important factors (or phenomena) associated with the air-ingress accident by using a root-cause analysis. By preventing main causes of the important events identified in the root-cause diagram, the basic air-ingress mitigation ideas can be conceptually derived. The main concepts include (1) preventing structural degradation of graphite supporters; (2) preventing local stress concentration in the supporter; (3) preventing graphite oxidation; (4) preventing air ingress; (5) preventing density gradient driven flow; (4) preventing fluid density gradient; (5) preventing fluid temperature gradient; (6) preventing high temperature. Based on the basic concepts listed above, various air

  3. Air Ingress Analyses on a High Temperature Gas-Cooled Reactor

    SciTech Connect

    Oh, Chang H; Moore, Richard Leroy; Merrill, Brad Johnson; Petti, David Andrew

    2001-11-01

    A primary-pipe break accident is one of the design-basis accidents of a high-temperature gas-cooled reactor (HTGR). When this accident occurs, air is anticipated to enter the reactor core from the break and oxidize the in-core graphite structure in the modular pebble bed reactor (MPBR). This paper presents the results of the graphite oxidation model developed as part of the Idaho National Engineering and Environmental Laboratory's Direct Research and Development effort. Although gas reactors have been tried in the past with limited success, the innovations of modularity and integrated state-ofart control systems coupled with improved fuel design and a pebble bed core make this design potentially very attractive from an economic and technical perspective. A schematic diagram on a reference design of the MPBR has been established on a major component level (INEEL & MIT, 1999). Steady-state and transient thermal hydraulics models will be produced with key parameters established for these conditions at all major components. Development of an integrated plant model to allow for transient analysis on a more sophisticated level is now being developed. In this paper, preliminary results of the hypothetical air ingress are presented. A graphite oxidation model was developed to determine temperature and the control mechanism in the spherical graphite geometry.

  4. Oxidative Stress and Air Pollution Exposure

    PubMed Central

    Lodovici, Maura; Bigagli, Elisabetta

    2011-01-01

    Air pollution is associated with increased cardiovascular and pulmonary morbidity and mortality. The mechanisms of air pollution-induced health effects involve oxidative stress and inflammation. As a matter of fact, particulate matter (PM), especially fine (PM2.5, PM < 2.5 μm) and ultrafine (PM0.1, PM < 0.1 μm) particles, ozone, nitrogen oxides, and transition metals, are potent oxidants or able to generate reactive oxygen species (ROS). Oxidative stress can trigger redox-sensitive pathways that lead to different biological processes such as inflammation and cell death. However, it does appear that the susceptibility of target organ to oxidative injury also depends upon its ability to upregulate protective scavenging systems. As vehicular traffic is known to importantly contribute to PM exposure, its intensity and quality must be strongly relevant determinants of the qualitative characteristics of PM spread in the atmosphere. Change in the composition of this PM is likely to modify its health impact. PMID:21860622

  5. Evaluation of a Combined Ultraviolet Photocatalytic Oxidation(UVPCO)/Chemisorbent Air Cleaner for Indoor Air Applications

    SciTech Connect

    Hodgson, Alfred T.; Destaillats, Hugo; Hotchi, Toshifumi; Fisk,William J.

    2007-02-01

    We previously reported that gas-phase byproducts of incomplete oxidation were generated when a prototype ultraviolet photocatalytic oxidation (UVPCO) air cleaner was operated in the laboratory with indoor-relevant mixtures of VOCs at realistic concentrations. Under these conditions, there was net production of formaldehyde and acetaldehyde, two important indoor air toxicants. Here, we further explore the issue of byproduct generation. Using the same UVPCO air cleaner, we conducted experiments to identify common VOCs that lead to the production of formaldehyde and acetaldehyde and to quantify their production rates. We sought to reduce the production of formaldehyde and acetaldehyde to acceptable levels by employing different chemisorbent scrubbers downstream of the UVPCO device. Additionally, we made preliminary measurements to estimate the capacity and expected lifetime of the chemisorbent media. For most experiments, the system was operated at 680-780 m{sup 3}/h (400-460 cfm). A set of experiments was conducted with common VOCs introduced into the UVPCO device individually and in mixture. Compound conversion efficiencies and the production of formaldehyde and acetaldehyde were determined by comparison of compound concentrations upstream and downstream of the reactor. There was general agreement between compound conversions efficiencies determined individually and in the mixture. This suggests that competition among compounds for active sites on the photocatalyst surface will not limit the performance of the UVPCO device when the total VOC concentration is low. A possible exception was the very volatile alcohols, for which there were some indications of competitive adsorption. The results also showed that formaldehyde was produced from many commonly encountered VOCs, while acetaldehyde was generated by specific VOCs, particularly ethanol. The implication is that formaldehyde concentrations are likely to increase when an effective UVPCO air cleaner is used in

  6. Photocatalyzed oxidation of ethanol and acetaldehyde in humidified air

    SciTech Connect

    Sauer, M.L.; Ollis, D.F.

    1996-02-01

    Photocatalysis is considered as a potential air treatment and purification technology. Photocatalyzed oxidation of ethanol and acetaldehyde in humidified air was carried out to establish a first complete kinetic model for a photocatalyzed multispecies network. Two photocatalysts were examined in a batch, recirculation reactor, near-UV illuminated TiO{sub 2} (anatase) coated (i) on the surface of a nonporous quartz glass plate and (ii) on a porous ceramic honeycomb monolith. The former contained only illuminated (active) surfaces, the latter consisted of substantial {open_quotes}dark{close_quotes} surfaces coated with a thin layer of illuminated (active) catalyst. Ethanol was photooxidized to acetaldehyde and formaldehyde intermediates, and eventually to carbon dioxide and water products. The catalyst and monolith surfaces adsorbed appreciable fractions of the trace ethanol, acetaldehyde, formaldehyde, carbon dioxide and water present. Ethanol, acetaldehyde, and carbon dioxide adsorption isotherms were measured on both catalysts; the formaldehyde adsorption isotherms were assumed identical to those of acetaldehyde. On the fully illuminated glass plate reactor, all four species were accounted for, and closure of a transient carbon mass balance was demonstrated. Completion of a transient carbon mass balance on the monolith reactor required inclusion of additional reaction intermediates (acetic and formic acids), which appear to reversibly accumulate on only the dark surfaces. The ethanol and acetaldehyde photocatalyzed oxidation kinetic networks were modeled using Langmuir-Hinshelwood rate forms combined with adsorption isotherms for reactant, intermediates, and product CO{sub 2}. For both the quartz plate and monolith catalysts, satisfactory kinetic models were developed to predict the entire time course of ethanol and acetaldehyde multicomponent batch conversions. 43 refs., 16 figs.

  7. Photocatalytic oxidation of methyl orange in a three-phase fluidized bed reactor.

    PubMed

    Nam, Wooseok; Kim, Jimin; Han, Guiyoung

    2002-06-01

    The photocatalytic oxidation of methyl orange under weak illumination conditions was carried out in two different types of fluidized bed reactors. TiO2 powder was employed as the photocatalysts and a 15 W low pressure mercury lamp was used as the light source and the reactor volume was 2.5 l. The parametric study of photocatalytic oxidation of methyl orange in two different types of fluidized beds was investigated; effect of catalyst loadings, pH, air flow rate, initial concentration and oxygen concentration on the oxidation reaction rate. The experimental results were analyzed in conjunction with the characteristics of fluidized bed and the reactor geometry effect on the reaction rate was analyzed. PMID:12108693

  8. Investigation of vessel exterior air cooling for a HLMC reactor

    SciTech Connect

    Sienicki, J. J.; Spencer, B. W.

    2000-01-13

    The Secure Transportable Autonomous Reactor (STAR) concept under development at Argonne National Laboratory provides a small (300 MWt) reactor module for steam supply that incorporates design features to attain proliferation resistance, heightened passive safety, and improved cost competitiveness through extreme simplification. Examples are the achievement of 100%+ natural circulation heat removal from the low power density/low pressure drop ultra-long lifetime core and utilization of lead-bismuth eutectic (LBE) coolant enabling elimination of main coolant pumps as well as the need for an intermediate heat transport circuit. It is required to provide a passive means of removing decay heat and effecting reactor cooldown in the event that the normal steam generator heat sink, including its normal shutdown heat removal mode, is postulated to be unavailable. In the present approach, denoted as the Reactor Exterior Cooling System (RECS), passive decay heat removal is provided by cooling the outside of the containment/guard vessel with air. RECS is similar to the Reactor Vessel Auxiliary Cooling System (RVACS) incorporated into the PRISM design. However, to enhance the heat removal, RECS incorporates fins on the containment vessel exterior to enhance heat transfer to air as well as removable steel venetian conductors that provide a conduction heat transfer path across the reactor vessel-containment vessel gap to enhance heat transfer between the vessels. The objective of the present work is to investigate the effectiveness of air cooling in removing heat from the vessel and limiting the coolant temperature increase following a sudden complete loss of the steam generator heat sink.

  9. Operation of staged membrane oxidation reactor systems

    DOEpatents

    Repasky, John Michael

    2012-10-16

    A method of operating a multi-stage ion transport membrane oxidation system. The method comprises providing a multi-stage ion transport membrane oxidation system with at least a first membrane oxidation stage and a second membrane oxidation stage, operating the ion transport membrane oxidation system at operating conditions including a characteristic temperature of the first membrane oxidation stage and a characteristic temperature of the second membrane oxidation stage; and controlling the production capacity and/or the product quality by changing the characteristic temperature of the first membrane oxidation stage and/or changing the characteristic temperature of the second membrane oxidation stage.

  10. Carbon monoxide oxidation rates computed for automobile thermal reactor conditions

    NASA Technical Reports Server (NTRS)

    Brokaw, R. S.; Bittker, D. A.

    1972-01-01

    Carbon monoxide oxidation rates in thermal reactors for exhaust manifolds are computed by integrating differential equations for system of twenty-nine reversible chemical reactions. Reactors are noncatalytic replacements for conventional exhaust manifolds and are a system for reducing carbon monoxide and hydrocarbons in automobile exhausts.

  11. 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.

  12. 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.

  13. Nitric oxide flow tagging in unseeded air.

    PubMed

    Dam, N; Klein-Douwel, R J; Sijtsema, N M; Meulen, J J

    2001-01-01

    A scheme for molecular tagging velocimetry is presented that can be used in air flows without any kind of seeding. The method is based on the local and instantaneous creation of nitric oxide (NO) molecules from N(2) and O(2) in the waist region of a focused ArF excimer laser beam. This NO distribution is advected by the flow and can be visualized any time later by laser-induced fluorescence in the gamma bands. The creation of NO is confirmed by use of an excitation spectrum. Two examples of the application of the new scheme for air-flow velocimetry are given in which single laser pulses are used for creation and visualization of NO. PMID:18033499

  14. Ethylene oxidation chemistry in a well-stirred reactor

    SciTech Connect

    Marinov, N.; Malte, P.

    1994-09-01

    Ethylene is an important intermediate in the combustion of methane, larger aliphatic hydrocarbons, and aromatics. Detailed fuel-lean C{sub 2}H{sub 4}H{sub 2}O/air well-stirred reactor data by Thornton were used to analyze reported combustion chemistry mechanisms and the development of this study`s ethylene oxidation mechanism. The data set had been obtained for the temperature range 1,003 to 1,253 K and ethylene-oxygen equivalence ratio range 0.086 to 0.103, at atmospheric pressure. Mechanisms were derived from reaction sets of Westbrook and Pitz, and Dagaut, Cathonnet and Boettner. Examination of each reported mechanism indicated unusually large kinetic rates for the vinyl decomposition reaction were used in order to obtain agreement with the Thornton data set. An ethylene oxidation model was developed in order to address the mechanistic problems of the previous models. This study`s mechanism well simulated the overall rate of ethylene oxidation and concentration profiles of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6}. Successful predictions by the model were dependent on a new high temperature vinyl oxidation reaction route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O with a branching ratio of 1.19--1.21 at 1,053 K to 1.63--2.47 at 1,253 K. The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction. 132 refs.

  15. Reactor modeling of the oxidative coupling of methane in membranes reactors

    SciTech Connect

    Lu, Y.; Ramachandra, A.; Ma, Y.H.

    1994-12-31

    A reactor model has been developed to analyze the performance of membrane reactors for the high temperature oxidative coupling of methane and to compare their operation with fixed bed reactors. Three reactor configurations of the shell and tube type were this study: a conventional fixed bed reactor, a tubular porous membrane reactor, dense membrane reactor. For the membrane reactors, oxygen is fed on the shell side and methane into the tube side, and the catalyst is present only inside the tube. Both streams are diluted with helium and the feed ratio is maintained at a methane to oxygen ratio of 2:1 for all three configurations. The ratio of the volumetric flow rate of each reactant to the amount of catalyst is kept the same for the three configurations. Kinetic equations for the oxidative coupling of methane have been taken from the simplified mechanism on Li/MgO proposed by Tung and Lobban, where C{sub 2}H{sub 6}, CO{sub 2} and H{sub 2}O are the reaction products considered. The modeling study indicates an improved performance of the membrane reactors over the conventional packed bed reactor. For the porous membrane reactor, a 4 angstrom pore size membrane gives higher C{sub 2}H{sub 6} selectivities and C{sub 2}H{sub 6} yields than a 40 Angstrom pore size membrane. For the dense membrane reactor, a lower oxygen permeability gives higher C{sub 2}H{sub 6} yield. Of the three types of reactors, the dense membrane reactor offers the highest C{sub 2}H{sub 6} yields but a longer reactor length is needed because of the lower permeation rate of oxygen from the shell to the tube side, and hence the lower oxygen partial pressure and lower reaction rate on the tube side.

  16. Oxidative coupling of methane using inorganic membrane reactor

    SciTech Connect

    Ma, Y.H.; Moser, W.R.; Dixon, A.G.

    1995-12-31

    The goal of this research is to improve the oxidative coupling of methane in a catalytic inorganic membrane reactor. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and relatively higher yields than in fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for formation of CO{sub x} products. Such gas phase reactions are a cause for decreased selectivity in oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Modeling work which aimed at predicting the observed experimental trends in porous membrane reactors was also undertaken in this research program.

  17. Cross-flow electrochemical reactor cells, cross-flow reactors, and use of cross-flow reactors for oxidation reactions

    DOEpatents

    Balachandran, Uthamalingam; Poeppel, Roger B.; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Udovich, Carl A.

    1994-01-01

    This invention discloses cross-flow electrochemical reactor cells containing oxygen permeable materials which have both electron conductivity and oxygen ion conductivity, cross-flow reactors, and electrochemical processes using cross-flow reactor cells having oxygen permeable monolithic cores to control and facilitate transport of oxygen from an oxygen-containing gas stream to oxidation reactions of organic compounds in another gas stream. These cross-flow electrochemical reactors comprise a hollow ceramic blade positioned across a gas stream flow or a stack of crossed hollow ceramic blades containing a channel or channels for flow of gas streams. Each channel has at least one channel wall disposed between a channel and a portion of an outer surface of the ceramic blade, or a common wall with adjacent blades in a stack comprising a gas-impervious mixed metal oxide material of a perovskite structure having electron conductivity and oxygen ion conductivity. The invention includes reactors comprising first and second zones seprated by gas-impervious mixed metal oxide material material having electron conductivity and oxygen ion conductivity. Prefered gas-impervious materials comprise at least one mixed metal oxide having a perovskite structure or perovskite-like structure. The invention includes, also, oxidation processes controlled by using these electrochemical reactors, and these reactions do not require an external source of electrical potential or any external electric circuit for oxidation to proceed.

  18. The study of leachate treatment by using three advanced oxidation process based wet air oxidation

    PubMed Central

    2013-01-01

    Wet air oxidation is regarded as appropriate options for wastewater treatment with average organic compounds. The general purpose of this research is to determine the efficiency of three wet air oxidation methods, wet oxidation with hydrogen peroxide and absorption with activated carbon in removing organic matter and nitrogenous compounds from Isfahan's urban leachate. A leachate sample with the volume of 1.5 liters entered into a steel reactor with the volume of three liters and was put under a 10-bar pressure, at temperatures of 100, 200, and 300° as well as three retention times of 30, 60, and 90 minutes. The sample was placed at 18 stages of leachate storage ponds in Isfahan Compost Plant with the volume of 20 liters, using three WPO, WAO methods and a combination of WAO/GAC for leachate pre-treatment. Thirty percent of pure oxygen and hydrogen peroxide were applied as oxidation agents. The COD removal efficiency in WAO method is 7.8-33.3%, in BOD is 14.7-50.6%, the maximum removal percentage (efficiency) for NH4-N is 53.3% and for NO3-N is 56.4-73.9%. The removal efficiency of COD and BOD5 is 4.6%-34 and 24%-50 respectively in WPO method. Adding GAC to the reactor, the removal efficiency of all parameters was improved. The maximum removal efficiency was increased 48% for COD, 31%-43.6 for BOD5 by a combinational method, and the ratio of BOD5/COD was also increased to 90%. In this paper, WAO and WPO process was used for Leachate pre-treatment and WAO/GAC combinational process was applied for improving the organic matter removal and leachate treatment; it was also determined that the recent process is much more efficient in removing resistant organic matter. PMID:23369258

  19. 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.

  20. OXIDATIVE COUPLING OF METHANE USING INORGANIC MEMBRANE REACTORS

    SciTech Connect

    Dr. Y.H. Ma; Dr. W.R. Moser; Dr. A.G. Dixon; Dr. A.M. Ramachandra; Dr. Y. Lu; C. Binkerd

    1998-04-01

    The objective of this research is to study the oxidative coupling of methane in catalytic inorganic membrane reactors. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and higher yields than in conventional non-porous, co-feed, fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for the formation of CO{sub x} products. Such gas phase reactions are a cause of decreased selectivity in the oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Membrane reactor technology also offers the potential for modifying the membranes both to improve catalytic properties as well as to regulate the rate of the permeation/diffusion of reactants through the membrane to minimize by-product generation. Other benefits also exist with membrane reactors, such as the mitigation of thermal hot-spots for highly exothermic reactions such as the oxidative coupling of methane. The application of catalytically active inorganic membranes has potential for drastically increasing the yield of reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity.

  1. Specific features of aluminum nanoparticle water and wet air oxidation

    SciTech Connect

    Lozhkomoev, Aleksandr S. Glazkova, Elena A. Svarovskaya, Natalia V. Bakina, Olga V. Kazantsev, Sergey O. Lerner, Marat I.

    2015-10-27

    The oxidation processes of the electrically exploded aluminum nanopowders in water and in wet air are examined in the paper. The morphology of the intermediate reaction products of aluminum oxidation has been studied using the transmission electron microscopy. It was shown that the aluminum nanopowder water oxidation causes the formation of the hollow spheres with mesoporous boehmite nanosheets coating. The wedge-like bayerite particles are formed during aluminum nanopowder wet air oxidation.

  2. Specific features of aluminum nanoparticle water and wet air oxidation

    NASA Astrophysics Data System (ADS)

    Lozhkomoev, Aleksandr S.; Glazkova, Elena A.; Svarovskaya, Natalia V.; Bakina, Olga V.; Kazantsev, Sergey O.; Lerner, Marat I.

    2015-10-01

    The oxidation processes of the electrically exploded aluminum nanopowders in water and in wet air are examined in the paper. The morphology of the intermediate reaction products of aluminum oxidation has been studied using the transmission electron microscopy. It was shown that the aluminum nanopowder water oxidation causes the formation of the hollow spheres with mesoporous boehmite nanosheets coating. The wedge-like bayerite particles are formed during aluminum nanopowder wet air oxidation.

  3. Interim results from UO/sub 2/ fuel oxidation tests in air

    SciTech Connect

    Campbell, T.K.; Gilbert, E.R.; Thornhill, C.K.; White, G.D.; Piepel, G.F.; Griffin, C.W.j

    1987-08-01

    An experimental program is being conducted at Pacific Northwest Laboratory (PNL) to extend the characterization of spent fuel oxidation in air. To characterize oxidation behavior of irradiated UO/sub 2/, fuel oxidation tests were performed on declad light-water reactor spent fuel and nonirradited UO/sub 2/ pellets in the temperature range of 135 to 250/sup 0/C. These tests were designed to determine the important independent variables that might affect spent fuel oxidation behavior. The data from this program, when combined with the test results from other programs, will be used to develop recommended spent fuel dry-storage temperature limits in air. This report describes interim test results. The initial PNL investigations of nonirradiated and spent fuels identified the important testing variables as temperature, fuel burnup, radiolysis of the air, fuel microstructure, and moisture in the air. Based on these initial results, a more extensive statistically designed test matrix was developed to study the effects of temperature, burnup, and moisture on the oxidation behavior of spent fuel. Oxidation tests were initiated using both boiling-water reactor and pressurized-water reactor fuels from several different reactors with burnups from 8 to 34 GWd/MTU. A 10/sup 5/ R/h gamma field was applied to the test ovens to simulate dry storage cask conditions. Nonirradiated fuel was included as a control. This report describes experimental results from the initial tests on both the spent and nonirradiated fuels and results to date on the tests in a 10/sup 5/ R/h gamma field. 33 refs., 51 figs., 6 tabs.

  4. Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents

    SciTech Connect

    Chang Ho Oh; Eung Soo Kim; Hee Cheon No; Nam Zin Cho

    2008-12-01

    The US Department of Energy is performing research and development (R&D) that focuses on key phenomena that are important during challenging scenarios that may occur in the Next Generation Nuclear Plant (NGNP) Program / GEN-IV Very High Temperature Reactor (VHTR). Phenomena identification and ranking studies (PIRT) to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important (Schultz et al., 2006). Consequently, the development of advanced air ingress-related models and verification and validation (V&V) are very high priority for the NGNP program. Following a loss of coolant and system depressurization, air will enter the core through the break. Air ingress leads to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heat-up of the bottom reflector and the reactor core and will cause the release of fission products eventually. The potential collapse of the bottom reflector because of burn-off and the release of CO lead to serious safety problems. For estimation of the proper safety margin we need experimental data and tools, including accurate multi-dimensional thermal-hydraulic and reactor physics models, a burn-off model, and a fracture model. We also need to develop effective strategies to mitigate the effects of oxidation. The results from this research will provide crucial inputs to the INL NGNP/VHTR Methods R&D project. This project is focused on (a) analytical and experimental study of air ingress caused by density-driven, stratified, countercurrent flow, (b) advanced graphite oxidation experiments, (c) experimental study of burn-off in the bottom reflector, (d) structural tests of the burnt-off bottom reflector, (e) implementation of advanced models developed during the previous tasks into the GAMMA code, (f) full air ingress and oxidation mitigation analyses, (g) development of core neutronic models, (h) coupling of the core neutronic and thermal hydraulic models, and (i

  5. ANALYSIS OF MODIFIED WET-AIR OXIDATION FOR SOIL DETOXIFICATION

    EPA Science Inventory

    The report presents the results of research on wet-air oxidation as a method for the destruction of hazardous wastes. For organics in the presence of large amounts of water, the water need not be vaporized during wet-air oxidation, an attractive characteristic for energy conserva...

  6. Characterizing the Amount and Chemistry of Biogenic SOA Formation from Pine Forest Air Using a Flow Reactor

    NASA Astrophysics Data System (ADS)

    Palm, B. B.; Ortega, A. M.; Campuzano Jost, P.; Day, D. A.; Fry, J.; Zarzana, K. J.; Draper, D. C.; Brown, S. S.; Kaser, L.; Karl, T.; Jud, W.; Hansel, A.; Hodzic, A.; Dube, W. P.; Wagner, N. L.; Brune, W. H.; Jimenez, J. L.

    2013-12-01

    The amount and chemistry of biogenic secondary organic aerosol (SOA) formation was characterized as a function of oxidant exposure using a Potential Aerosol Mass (PAM) oxidative flow reactor, sampling air in a terpene- and MBO-dominated pine forest during the 2011 BEACHON-RoMBAS field campaign at the U.S. Forest Service Manitou Forest Experimental Observatory in the Colorado Rocky Mountains. In the reactor, a chosen oxidant (OH, O3, or NO3) was generated and stepped over a range of values up to 10,000 times ambient levels, accelerating the gas-phase and heterogeneous oxidative aging of volatile organic compounds (VOCs), inorganic gases, and preexisting aerosol. The resulting SOA formation was measured using an Aerodyne HR-ToF-AMS, a TSI SMPS and a PTR-TOF-MS. Oxidative processing in the flow reactor was equivalent to a few hours up to ~20 days of atmospheric aging during the ~4-min reactor residence time. During BEACHON-RoMBAS, OH oxidation led to a net production of up to several μg/m3 of SOA at intermediate exposures (1-10 equivalent days) but resulted in net loss of OA mass (up to ~30%) at higher OH exposures (10-20 equivalent days), demonstrating the competing effects of functionalization/condensation vs. fragmentation/evaporation reactions as OH exposure increased. O3 and NO3 oxidation led to smaller (up to 0.5 μg/m3) SOA production, and loss of SOA mass due to fragmentation reactions was not observed. OH oxidation resulted in f44 vs. f43 and Van Krevelen diagram (H:C vs. O:C) slopes similar to ambient oxidation, suggesting the flow reactor oxidation pathways are similar to those in ambient air. Organic nitrate SOA production was observed from NO3 radical oxidation only. New particle formation was observed from OH oxidation, but not O3 or NO3 oxidation under our experimental conditions. An enhancement of SOA production under the influence of anthropogenic pollution (Denver) was also observed. High-resolution AMS measurements showed that the O:C and H

  7. AIR QUALITY CRITERIA FOR OZONE AND RELATED PHOTOCHEMICAL OXIDANTS

    EPA Science Inventory

    The Clean Air Act requires periodic (5-year) update revision of criteria and National Ambient Air Quality Standards (NAAQS) for Ozone. The previous revision of the criteria contained in the Air Quality Criteria Document (AQCD) for Ozone and Related Photochemical Oxidants was co...

  8. Effect of Gadolinium Doping on the Air Oxidation of Uranium Dioxide

    SciTech Connect

    Scheele, Randall D.; Hanson, Brady D.; Cumblidge, Stephen E.; Jenson, Evan D.; Kozelisky, Anne E.; Sell, Rachel L.; MacFarlan, Paul J.; Snow, Lanee A.

    2004-12-04

    Researchers at the Pacific Northwest National Laboratory (PNNL) investigated the effects of gadolinia concentration on the air oxidization of gadolinia-doped uranium dioxide using thermogravimetry and differential scanning calorimetry to determine if such doping could improve uranium dioxide's stability as a nuclear fuel during potential accident scenarios in a nuclear reactor or during long-term disposal. We undertook this study to determine whether the resistance of the uranium dioxide to oxidation to the orthorhombic U3O8 with its attendant crystal expansion could be prevented by addition of gadolinia. Our studies found that gadolinium has little effect on the thermal initiation of the first step of the reported two-step air oxidation of UO2; however, increasing gadolinia content does stabilize the initial tetragonal or cubic product allowing significant oxidation before the second expansive step to U3O8 begins.

  9. Oxide modified air electrode surface for high temperature electrochemical cells

    DOEpatents

    Singh, Prabhakar; Ruka, Roswell J.

    1992-01-01

    An electrochemical cell is made having a porous cermet electrode (16) and a porous lanthanum manganite electrode (14), with solid oxide electrolyte (15) between them, where the lanthanum manganite surface next to the electrolyte contains a thin discontinuous layer of high surface area cerium oxide and/or praseodymium oxide, preferably as discrete particles (30) in contact with the air electrode and electrolyte.

  10. Air pollution and circulating biomarkers of oxidative stress

    PubMed Central

    Staimer, Norbert; Vaziri, Nosratola D.

    2013-01-01

    Chemical components of air pollutant exposures that induce oxidative stress and subsequent inflammation may be partly responsible for associations of cardiovascular morbidity and mortality with airborne particulate matter and combustion-related pollutant gasses. However, epidemiologic evidence regarding this is limited. An exposure-assessment approach is to measure the oxidative potential of particle mixtures because it is likely that hundreds of correlated chemicals are involved in overall effects of air pollution on health. Oxidative potential likely depends on particle composition and size distribution, especially ultrafine particle concentration, and on transition metals and certain semivolatile and volatile organic chemicals. For health effects, measuring systemic oxidative stress in the blood is one feasible approach, but there is no universal biomarker of oxidative stress and there are many potential target molecules (lipids, proteins, DNA, nitric oxide, etc.), which may be more or less suitable for specific study goals. Concurrent with the measurement of oxidative stress, it is important to measure gene and/or protein expression of endogenous antioxidant enzymes because they can modify relations between oxidative stress biomarkers and air pollutants. Conversely, the expression and activities of these enzymes are modified by oxidative stress. This interplay will likely determine the observed effects of air pollutants on systemic inflammatory and thrombotic mediators and related clinical outcomes. Studies are needed to assess the reliability and validity of oxidative stress biomarkers, evaluate differences in associations between oxidative stress biomarkers and various pollutant measurements (mass, chemical components, and oxidative potential), and evaluate impacts of antioxidant responses on these relations. PMID:23626660

  11. The dynamics of packed bed reactors loaded with oxide catalysts

    SciTech Connect

    Arnold, E.W.; Sundaresan, S.

    1987-01-01

    The lattice of an oxide catalyst used for oxidation reactions can act as a reservoir for oxygen, storing and releasing it for reactions at the catalyst surface under appropriate conditions. The implication of this oxygen storage property on the dynamic response characteristics of oxide catalysts has been investigated through an experimental study of 2-butene oxidation over vanadium oxide as a model reaction. Isothermal reaction rate measurements in a differential reactor and nonisothermal studies in a single pellet reactor have been carried out. Following a step increase in the feed butene concentration, isothermal reaction rate overshoot and pellet temperature overshoot were observed. These observations could be modelled in a qualitatively correct way by a very simple model accounting for the dynamic participation of lattice oxygen in the catalytic reactions. It is demonstrated through model simulations that the ignition characteristics of a catalyst pellet are significantly affected by the participation of the lattice oxygen, when steady state multiplicity is present. The initiation of dynamic runaway of a wall-cooled packed reactor, upon start-up, owing to the participation of lattice, is illustrated through simulations.

  12. NEUTRONIC REACTOR POWER PLANT

    DOEpatents

    Metcalf, H.E.

    1962-12-25

    This patent relates to a nuclear reactor power plant incorporating an air-cooled, beryllium oxide-moderated, pebble bed reactor. According to the invention means are provided for circulating a flow of air through tubes in the reactor to a turbine and for directing a sidestream of the circu1ating air through the pebble bed to remove fission products therefrom as well as assist in cooling the reactor. (AEC)

  13. Wet-air oxidation cleans up black wastewater

    SciTech Connect

    Not Available

    1993-09-01

    Sterling Organics produces the analgesic paracetamol (acetaminophen) at its Dudley, England, plant. The wastewater from the batch process contains intermediates such as para-aminophenol (PAP) and byproducts such as thiosulfates, sulfites and sulfides. To stay ahead of increasingly strict environmental legislation, Sterling Organics installed a wet-air oxidation system at the Dudley facility in August 1992. The system is made by Zimpro Environmental Inc. (Rothschild, Wis.). Zimpro's wet-air oxidation system finds a way around the limitations of purely chemical or physical processes. In the process, compressed air at elevated temperature and pressure oxidizes the process intermediates and byproducts and removes the color from the wastewater.

  14. NEXAFS Study of Air Oxidation for Mg Nanoparticle Thin Film

    NASA Astrophysics Data System (ADS)

    Ogawa, S.; Murakami, S.; Shirai, K.; Nakanishi, K.; Ohta, T.; Yagi, S.

    2013-03-01

    The air oxidation reaction of Mg nanoparticle thin film has been investigated by Mg K-edge NEXAFS technique. It is revealed that MgO is formed on the Mg nanoparticle surfaces at the early stage of the air oxidation for Mg nanoparticle thin film. The simulation of NEXAFS spectrum using standard spectra indicates the existence of complex magnesium carbonates (x(MgCO3).yMg(OH2).z(H2O)) in addition to MgO at the early stage of the air oxidation.

  15. Validation of the RVACS (Reactor Vessel Auxiliary Cooling System)/RACS (Reactor Air Cooling System) model in SASSYS-1

    SciTech Connect

    Dunn, F.E.

    1987-01-01

    The SASSYS-1 LMR systems analysis code contains a model for transient analysis of heat removal by a RVACS (Reactor Vessel Auxiliary Cooling System) or a RACS (Reactor Air Cooling System) in an LMR (Liquid Metal Reactor). This model has been validated by comparisons of model predictions with experimental data from a large scale RVACS/RACS simulation experiment performed at Argonne National Laboratory. 4 refs., 1 fig.

  16. 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.

  17. Seismic analysis of reactor exhaust air filter compartment

    SciTech Connect

    Gong, Chung; Funderburk, E.L.; Jerrell, J.W.

    1990-09-24

    The Filter Compartment (FC) in this analysis is a generic reactor airborne activity confinement filter compartment which possesses all the essential physical and mechanical properties of the Savannah River Site (SRS) confinement filters of Reactor Buildings K, L, and P. The filters belong to the Airborne Activity Confinement System (AACS). These filters absorb a significant amount of radioactive effluents from the exhausting air. The seismic excitation is input indirectly from the output of the seismic analysis of the 105 exhaust stack building in the form of floor response spectra. However, the 105 exhaust stack building was analyzed for seismic motions defined by free-field ground response spectra with a ZPA (Zero Period Acceleration) of 0.2G for all three orthogonal components of ground motion and a shape consistent with USNRC Regulatory Guide 1.60. Based upon equivalent dynamic analysis of the FC, DuPont engineers suggested modifications on the existing FC with heavy I-section beams [1]. The scope of this ``phase I`` analysis, as requested by Seismic Engineering [2], is to carry out a ``scoping analysis`` of Frequency Analysis and Response Spectrum Analysis of the FC with DuPont suggested conceptual modifications. Our suggestion was that the existing FC without conceptual modifications be analyzed first. However, the schedule urgency of the project and with guidance from the previous seismic analysis established the priority to perform the analysis for the FC with modifications in the ``phase I`` calculations.

  18. Seismic analysis of reactor exhaust air filter compartment

    SciTech Connect

    Gong, Chung; Funderburk, E.L.; Jerrell, J.W.

    1990-09-24

    The Filter Compartment (FC) in this analysis is a generic reactor airborne activity confinement filter compartment which possesses all the essential physical and mechanical properties of the Savannah River Site (SRS) confinement filters of Reactor Buildings K, L, and P. The filters belong to the Airborne Activity Confinement System (AACS). These filters absorb a significant amount of radioactive effluents from the exhausting air. The seismic excitation is input indirectly from the output of the seismic analysis of the 105 exhaust stack building in the form of floor response spectra. However, the 105 exhaust stack building was analyzed for seismic motions defined by free-field ground response spectra with a ZPA (Zero Period Acceleration) of 0.2G for all three orthogonal components of ground motion and a shape consistent with USNRC Regulatory Guide 1.60. Based upon equivalent dynamic analysis of the FC, DuPont engineers suggested modifications on the existing FC with heavy I-section beams (1). The scope of this phase I'' analysis, as requested by Seismic Engineering (2), is to carry out a scoping analysis'' of Frequency Analysis and Response Spectrum Analysis of the FC with DuPont suggested conceptual modifications. Our suggestion was that the existing FC without conceptual modifications be analyzed first. However, the schedule urgency of the project and with guidance from the previous seismic analysis established the priority to perform the analysis for the FC with modifications in the phase I'' calculations.

  19. Air Quality Criteria for Sulfur Oxides.

    ERIC Educational Resources Information Center

    National Air Pollution Control Administration (DHEW), Washington, DC.

    Included is a literature review which comprehensively discusses knowledge of the sulfur oxides commonly found in the atmosphere. The subject content is represented by the 10 chapter titles: Physical and Chemical Properties and the Atmospheric Reactions of the Oxides of Sulfur; Sources and Methods of Measurements of Sulfur Oxides in the Atmosphere;…

  20. Reactor vessel using metal oxide ceramic membranes

    DOEpatents

    Anderson, Marc A.; Zeltner, Walter A.

    1992-08-11

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane.

  1. Simulation and optimization of an organic-impurity oxidization reactor with a fixed porous bed and an electric heating element

    NASA Astrophysics Data System (ADS)

    Gnezdilov, N. N.; Dobrego, K. V.; Kozlov, I. M.; Shmelev, E. S.

    2006-09-01

    A reactor for oxidization of low-caloric-value organic impurities contained in the air has been simulated. It comprises a tube with a recuperator, filled with a porous carcass mix, and includes a heating element. The influence of the heating-element placement, the heat losses through the upper cover of the reactor, the flow rate of a gas mixture, and the power of the heater on the maximum temperatures of the porous carcass and the gas and on the concentration of the incompletely oxidized organic impurity at the output of the reactor has been investigated. It is shown that, to burn an impurity completely, it will suffice to heat the gas δTe to 300 K. It has been established that it is best to place a heater at the level of the upper cut of the inner tube of the reactor.

  2. OXIDANT AIR POLLUTION AND WORK PERFORMANCE OF CITRUS HARVEST LABOR

    EPA Science Inventory

    The project assesses the effect of photochemical oxidants on the work performance of twelve individual citrus pickers in the South Coast Air Basin of southern California. A model of the picker's decision problem is constructed in which oxidants influence the individual's picking ...

  3. The Oxides of Nitrogen in Air Pollution.

    ERIC Educational Resources Information Center

    California State Air Resources Board, Sacramento.

    Research on the health effects of oxides of nitrogen and on the role of oxides of nitrogen in producing photochemical smog effects is presented in this report. Prepared by the California State Department of Public Health at the request of the State Legislature, it gives a comprehensive review of available information, as well as the need for air…

  4. AIR POLLUTION, OXIDATIVE STRESS AND NEUROTOXICITY.

    EPA Science Inventory

    Increased incidents of classic and variant forms of neurodegenerative diseases suggest that environmental chemicals and susceptibility factors (e.g., genetics, diseased states, obesity, etc.) may be contributory. Particulate matter (PM) is a type of air pollution that is associat...

  5. 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.

  6. Oxidation flow reactors (OFRs): overview of recent field and modeling studies

    NASA Astrophysics Data System (ADS)

    Jimenez, Jose-Luis; Palm, Brett B.; Peng, Zhe; Hu, Weiwei; Ortega, Amber M.; Li, Rui; Campuzano-Jost, Pedro; Day, Douglas A.; Stark, Harald; Brune, William H.; de Gouw, Joost; Schroder, Jason

    2016-04-01

    Oxidation flow reactors (OFRs) are popular tools for studying SOA formation and aging in both laboratory and field experiments. In an OFR, the concentration of an oxidant (OH, O3, or NO3) can be increased, leading to hours-months of equivalent atmospheric oxidation during the several-minute OFR residence time. Using gas- and particle-phase measurements from several recent field campaigns, we demonstrate SOA formation after oxidation of ambient air in an OFR. Typically, more SOA formation is observed from nighttime air than daytime air. This indicates that the concentration of SOA-forming gases in ambient air is relatively higher at night. Measured ambient VOCs are not able to explain the magnitude of SOA formation in the OFR, suggesting that typically unmeasured S/IVOCs (possibly VOC oxidation products or direct emissions) play a substantial intermediary role in ambient SOA formation. We also present highlights from recent OFR oxidant chemistry modeling studies. HOx, Ox, and photolysis chemistry was modeled for two common OH production methods (utilizing 185+254 nm UV light, or 254 nm only). OH exposure (OHexp) can be estimated within a factor of ~2 using model-derived equations, and can be verified in situ using VOC decay measurements. OHexp is strongly dependent on external OH reactivity, which may cause significant OH suppression in some circumstances (e.g., lab/source studies with high precursor concentrations). UV light photolysis and reaction with oxygen atoms are typically not major reaction pathways. Modeling the fate of condensable low-volatility organic gases (LVOCs) formed in an OFR suggests that LVOC fate is dependent on particle condensational sink. E.g., for the range of particle condensational sink at a remote pine forest, anywhere from 20-80% of produced LVOCs were predicted to condense onto aerosols for an OHexp of ~1 day, with the remainder lost to OFR or sampling line walls. Similar to large chamber wall loss corrections, a correction is needed

  7. Lithium oxides precipitation in nonaqueous Li-air batteries.

    PubMed

    Hou, Junbo; Yang, Min; Ellis, Michael W; Moore, Robert B; Yi, Baolian

    2012-10-21

    Lithium-air/oxygen battery is a rising star in the field of electrochemical energy storage as a promising alternative to lithium ion batteries. Nevertheless, this alluring system is still at its infant stage, and the breakthrough of lithium-air batteries into the energy market is currently constrained by a combination of scientific and technical challenges. Targeting at the air electrode in nonaqueous lithium-air batteries, this review attempts to summarize the knowledge about the fundamentals related to lithium oxides precipitation, which has been one of the vital and attractive aspects of the research communities of science and technology. PMID:22968061

  8. Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure

    SciTech Connect

    Smolik, G.R.; Petti, D.A.; Sharpe, J.P.; Schuetz, S.T.

    2000-10-31

    Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200 C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices.

  9. Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure

    SciTech Connect

    Smolik, Galen Richard; Petti, David Andrew; Sharpe, John Phillip; Schuetz, Stanley Thomas

    2000-10-01

    Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200°C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices

  10. Olefins by catalytic oxidation of alkanes in fluidized bed reactors

    SciTech Connect

    Bharadwaj, S.S.; Schmidt, L.D.

    1995-09-01

    The production of ethylene or syngas from ethane and olefins from propane, n-butane, and isobutane in the presence of air or O{sub 2} at atmospheric pressure has been examined over 100 {mu}m {alpha}-Al{sub 2}O{sub 3} beads coated with noble metals in a static fluidized bed reactor at contact times from 0.05 to 0.2 s. Variations in feed composition, preheating temperature, and flow rate were examined. 21 refs., 5 figs., 1 tab.

  11. Effect of fuel/air nonuniformity on nitric oxide emissions

    NASA Technical Reports Server (NTRS)

    Lyons, V. J.

    1979-01-01

    A flame tube combustor holding jet A fuel was used in experiments performed at a pressure of .3 Mpa and a reference velocity of 25 meters/second for three inlet air temperatures of 600, 700, and 800 K. The gas sample measurements were taken at locations 18 cm and 48 cm downstream of the perforated plate flameholder. Nonuniform fuel/air profiles were produced using a fuel injector by separately fueling the inner five fuel tubes and the outer ring of twelve fuel tubes. Six fuel/air profiles were produced for nominal overall equivalence ratios of .5 and .6. An example of three of three of these profiles and their resultant nitric oxide NOx emissions are presented. The uniform fuel/air profile cases produced uniform and relatively low profile levels. When the profiles were either center-peaked or edge-peaked, the overall mass-weighted nitric oxide levels increased.

  12. Practical Aspects for Characterizing Air Oxidation of Graphite

    SciTech Connect

    Contescu, Cristian I; Azad, Samina; Miller, Doug; Lance, Michael J; Baker, Frederick S; Burchell, Timothy D

    2008-01-01

    The efforts for designing of a meaningful and acceptable standard test method for characterization of kinetic parameters of air oxidation of graphite helped identify several practical issues that must be considered for the development of such a test. Using standard size (and shape) specimens, large enough in size to accommodate the inherent local microstructure differences between graphite samples, resulted in non-uniform oxidation profiles and preferential binder oxidation; this was not expected based on the linearity of Arrhenius plots and the (large) values of activation energy. It was found that the transition between the regimes 1 and 2 of graphite oxidation occurs gradually, depending both on the oxidation temperature and rate of oxygen supply. Nevertheless, measuring oxidation rates obtained on standard size samples provides a basis for a meaningful comparison among materials, which may serve as much needed information for predictive models.

  13. Oxidation of oleic acid monolayers at air/liquid interfaces

    NASA Astrophysics Data System (ADS)

    Voss, L. F.; Bazerbashi, M. F.; Beekman, C. P.; Hadad, C. M.; Allen, H. C.

    2006-12-01

    Field studies of marine and continental aerosols find that fatty acid films form on aqueous tropospheric aerosols. Oxidation of the acyl chains is thought to be key to aerosol growth. Oxidation of oleic acid monolayers by ozone was studied to understand the fate of fat-coated aerosols from both fresh and salt water sources. Using vibrational sum frequency generation spectroscopy and reflection absorption infrared spectroscopy, we present a molecular-level investigation of fatty acid monolayers at the air-water and air- sodium chloride solution interface and explore reactions with atmospheric oxidants by these model systems. Using sum frequency generation spectroscopy coupled with a Langmuir trough, concurrent spectroscopic and thermodynamic data were collected to obtain a molecular picture of the monolayers. No substantial difference was observed between oxidation of monolayers spread on water and on 0.6 molar sodium chloride solutions. Results indicate that depending on the size of the aerosol and the extent of oxidation, the subsequent oxidation products may not remain at the surface of these films, but instead be dissolved in the aqueous sub-phase of the aerosol particle. Results also indicate that oxidation of oleic acid could produce monolayers containing species that have no oxidized acyl chains.

  14. Ethylene oxidation in a well-stirred reactor

    SciTech Connect

    Marinov, N.M.; Malte, P.C.

    1994-10-01

    The detailed ethylene oxidation data set of Thornton, obtained for a well-stirred reactor operated fuel-lean at atmospheric pressure and for temperatures of 1003K to 1253K, is used as a basis for the comparison of chemical kinetic mechanisms reported in the literature and for the development of a new ethylene oxidation mechanism. The mechanisms examined are those of Westbrook and Pitz and Dagaut et al. These mechanisms indicated that unusually large rates for the vinyl decomposition reaction are required to obtain agreement with the Thornton data set. A new ethylene oxidation mechanism is developed in order to overcome some of the drawbacks of the previous mechanisms. The new mechanism closely simulates the overall rate of loss of ethylene, and the concentation of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6} measured for the stirred reactor. Predictions by this mechanism are dependent on a new high temperature vinyl oxidation route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O with a k{sub C2H3+O2=CH2CHO+O}/k{sub C2H3+O2=CH2O+HCO} branching ratio of 1.20 at 1053K to 2.05 at 1253K. The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction.

  15. 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.

  16. Effect of reactor heat transfer limitations on CO preferential oxidation

    NASA Astrophysics Data System (ADS)

    Ouyang, X.; Besser, R. S.

    Our recent studies of CO preferential oxidation (PrOx) identified systematic differences between the characteristic curves of CO conversion for a microchannel reactor with thin-film wall catalyst and conventional mini packed-bed lab reactors (m-PBR's). Strong evidence has suggested that the reverse water-gas-shift (r-WGS) side reaction activated by temperature gradients in m-PBR's is the source of these differences. In the present work, a quasi-3D tubular non-isothermal reactor model based on the finite difference method was constructed to quantitatively study the effect of heat transport resistance on PrOx reaction behavior. First, the kinetic expressions for the three principal reactions involved were formed based on the combination of experimental data and literature reports and their parameters were evaluated with a non-linear regression method. Based on the resulting kinetic model and an energy balance derived for PrOx, the finite difference method was then adopted for the quasi-3D model. This model was then used to simulate both the microreactor and m-PBR's and to gain insights into their different conversion behavior. Simulation showed that the temperature gradients in m-PBR's favor the reverse water-gas-shift (r-WGS) reaction, thus causing a much narrower range of permissible operating temperature compared to the microreactor. Accordingly, the extremely efficient heat removal of the microchannel/thin-film catalyst system eliminates temperature gradients and efficiently prevents the onset of the r-WGS reaction.

  17. Oxidation of oleic acid at air/liquid interfaces

    NASA Astrophysics Data System (ADS)

    Voss, Laura F.; Bazerbashi, Mohamad F.; Beekman, Christopher P.; Hadad, Christopher M.; Allen, Heather C.

    2007-03-01

    Oxidation of oleic acid monolayers by ozone was studied to understand the fate of fat-coated aerosols from both freshwater and saltwater sources. Oleic acid monolayers at the air/water interface and at the air/sodium chloride solution interface were investigated using surface-specific, broad-bandwidth, sum frequency generation spectroscopy. Complementary techniques of infrared reflection adsorption spectroscopy and surface pressure measurements taken during monolayer oxidation confirmed the sum frequency results. Using this nonlinear optical technique coupled with a Langmuir trough, concurrent spectroscopic and thermodynamic data were collected to obtain a molecular picture of the monolayers. No substantial difference was observed between oxidation of monolayers spread on water and on 0.6 M sodium chloride solutions. Results indicate that depending on the size of the aerosol and the extent of oxidation, the subsequent oxidation products may not remain at the surface of these films, but instead be dissolved in the aqueous subphase of the aerosol particle. Results also indicate that oxidation of oleic acid could produce monolayers containing species that have no oxidized acyl chains.

  18. Oxidation of oleic acid monolayers at air/liquid interfaces

    NASA Astrophysics Data System (ADS)

    Voss, Laura

    2008-03-01

    Field studies of marine and continental aerosols find that fatty acid films form on aqueous tropospheric aerosols. Oxidation of oleic acid monolayers by ozone was studied to understand the fate of fat-coated aerosols from both fresh and salt water sources. Using vibrational sum frequency generation spectroscopy and reflection absorption infrared spectroscopy, we present a molecular-level investigation of fatty acid monolayers at the air-water and air-sodium chloride solution interface and explore reactions with atmospheric oxidants by these model systems. Coupling sum frequency generation spectroscopy with a Langmuir trough, concurrent spectroscopic and thermodynamic data were collected to obtain a molecular picture of the monolayers. No substantial difference was observed between oxidation of monolayers spread on water and on 0.6 molar sodium chloride solutions. Results indicate that depending on the size of the aerosol and the extent of oxidation, the subsequent oxidation products may not remain at the surface of these films, but instead be dissolved in the aqueous sub-phase of the aerosol particle. Results also indicate that oxidation of oleic acid could produce monolayers containing species that have no oxidized acyl chains.

  19. HOMOGENEOUS AIR OXIDATION OF HYDROCARBONS UTILIZING MN AND CO CATALYSTS

    EPA Science Inventory

    Homogeneous Air Oxidation of Hydrocarbons Utilizing Mn and Co Catalysts

    Thomas M. Becker and Michael A. Gonzalez*, Sustainable Technology Division, Office of Research and Development; United States Environmental Protection Agency, 26 West Martin Luther King Drive, Mail Sto...

  20. AIR QUALITY CRITERIA FOR OXIDES OF NITROGEN (Final, 1982)

    EPA Science Inventory

    This document is an evaluation and assessment of scientific information relative to determining the health and welfare effects associated with exposure to various concentrations of nitrogen oxides in ambient air. The document is not intended as a complete, detailed literature rev...

  1. INTEGRATION OF PHOTOCATALYTIC OXIDATION WITH AIR STRIPPING OF CONTAMINATED AQUIFERS

    EPA Science Inventory

    Bench scale laboratory studies and pilot scale studies in a simulated field-test situation were performed to evaluate the integration of gas-solid ultaviolet (UV) photocatalytic oxidation (PCO) downstream if an air stripper unit as a technology for cost-effectively treating water...

  2. 75 FR 20595 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... for Oxides of Nitrogen and Oxides of Sulfur: First External Review Draft (75 FR 11877; March 12, 2010... AGENCY Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides... a proposal addressing the nitrogen oxides (NO X ) and sulfur oxides (SO X ) secondary...

  3. Passive air cooling of liquid metal-cooled reactor with double vessel leak accommodation capability

    DOEpatents

    Hunsbedt, Anstein; Boardman, Charles E.

    1995-01-01

    A passive and inherent shutdown heat removal method with a backup air flow path which allows decay heat removal following a postulated double vessel leak event in a liquid metal-cooled nuclear reactor. The improved reactor design incorporates the following features: (1) isolation capability of the reactor cavity environment in the event that simultaneous leaks develop in both the reactor and containment vessels; (2) a reactor silo liner tank which insulates the concrete silo from the leaked sodium, thereby preserving the silo's structural integrity; and (3) a second, independent air cooling flow path via tubes submerged in the leaked sodium which will maintain shutdown heat removal after the normal flow path has been isolated.

  4. Passive air cooling of liquid metal-cooled reactor with double vessel leak accommodation capability

    DOEpatents

    Hunsbedt, A.; Boardman, C.E.

    1995-04-11

    A passive and inherent shutdown heat removal method with a backup air flow path which allows decay heat removal following a postulated double vessel leak event in a liquid metal-cooled nuclear reactor is disclosed. The improved reactor design incorporates the following features: (1) isolation capability of the reactor cavity environment in the event that simultaneous leaks develop in both the reactor and containment vessels; (2) a reactor silo liner tank which insulates the concrete silo from the leaked sodium, thereby preserving the silo`s structural integrity; and (3) a second, independent air cooling flow path via tubes submerged in the leaked sodium which will maintain shutdown heat removal after the normal flow path has been isolated. 5 figures.

  5. Effects of different surfaces on the transport and deposition of ruthenium oxides in high temperature air

    NASA Astrophysics Data System (ADS)

    Vér, N.; Matus, L.; Pintér, A.; Osán, J.; Hózer, Z.

    2012-01-01

    In order to understand the behaviour of ruthenium oxides in the reactor coolant system during an air ingress accident, new tests were performed in the frame of the RUSET (RUthenium Separate Effect Test) experimental program. These aimed to ascertain the effects of different surfaces (quartz, stainless steel (SS), zirconium alloy, alumina, oxidised metal, and surfaces with Mo or Cs deposits) on the transport and decomposition of ruthenium oxides in air stream along the temperature gradient zone (1100-100 °C). The results demonstrated that the heterogeneous phase decomposition of RuO 3 and RuO 4 to RuO 2 is catalysed more efficiently by the quartz surface than by the SS or alumina surfaces. The presence of MoO 3 layers decreased the RuO x precipitation extent on all investigated surfaces. The trapping effect of Cs deposit on Ru in the temperature gradient zone was proved in the case of the SS surface. On the contrary, presence of Cs precipitate on alumina and especially on quartz surfaces was found to decrease their catalytic effect on the decomposition of ruthenium oxides, and thus increased the RuO 4 concentration in the outlet air. Similarly to the effect observed for Cs deposition, the presence of other fission products in the evaporation area (at 1100 °C) decreased the partial pressure of RuO 4 in the outlet air at the SS surface and increased it at quartz and alumina surfaces. When zirconium (E110) cladding material was placed in the temperature gradient zone, no Ru transmittance occurred until the high temperature end of the zirconium tube was completely oxidised. After the intense oxidation of E110, Ru release occurred only in the presence of other fission product species. Pre-oxidation of SS surfaces in steam had no significant effect on the Ru passage.

  6. Catalytic oxidative desulfurization of liquid hydrocarbon fuels using air

    NASA Astrophysics Data System (ADS)

    Sundararaman, Ramanathan

    Conventional approaches to oxidative desulfurization of liquid hydrocarbons involve use of high-purity, expensive water soluble peroxide for oxidation of sulfur compounds followed by post-treatment for removal of oxidized sulfones by extraction. Both are associated with higher cost due to handling, storage of oxidants and yield loss with extraction and water separation, making the whole process more expensive. This thesis explores an oxidative desulfurization process using air as an oxidant followed by catalytic decomposition of sulfones thereby eliminating the aforementioned issues. Oxidation of sulfur compounds was realized by a two step process in which peroxides were first generated in-situ by catalytic air oxidation, followed by catalytic oxidation of S compounds using the peroxides generated in-situ completing the two step approach. By this technique it was feasible to oxidize over 90% of sulfur compounds present in real jet (520 ppmw S) and diesel (41 ppmw S) fuels. Screening of bulk and supported CuO based catalysts for peroxide generation using model aromatic compound representing diesel fuel showed that bulk CuO catalyst was more effective in producing peroxides with high yield and selectivity. Testing of three real diesel fuels obtained from different sources for air oxidation over bulk CuO catalyst showed different level of effectiveness for generating peroxides in-situ which was consistent with air oxidation of representative model aromatic compounds. Peroxides generated in-situ was then used as an oxidant to oxidize sulfur compounds present in the fuel over MoO3/SiO2 catalyst. 81% selectivity of peroxides for oxidation of sulfur compounds was observed on MoO3/SiO2 catalyst at 40 °C and under similar conditions MoO3/Al2O3 gave only 41% selectivity. This difference in selectivity might be related to the difference in the nature of active sites of MoO3 on SiO2 and Al2O 3 supports as suggested by H2-TPR and XRD analyses. Testing of supported and bulk Mg

  7. Oxidation of nitrogen oxide in hybrid plasma-catalytic reactors based on DBD and Fe2O3

    NASA Astrophysics Data System (ADS)

    Jõgi, Indrek; Erme, Kalev; Haljaste, Ants; Laan, Matti

    2013-02-01

    In the present study, Fe2O3 was used as catalyst for the removal of NO in a hybrid plasma- catalytic reactor. The catalyst was located either directly inside the hybrid plasma-catalytic reactor or in a separate catalytic reactor, which followed ozone producing and injecting plasma reactor. Ozone production in such a reactor was dependent on the state of the electrode surface. The fresh catalyst ensured an order of magnitude smaller ozone concentration in the outlet of the hybrid reactor. After a short treatment of the catalyst with NO2, its ability to destroy ozone diminished but was regained after heating of the reactor up to 100 °C. Similarly to earlier results obtained with TiO2, the removal of NO in the hybrid reactor with Fe2O3 was enhanced compared to that in an ordinary plasma reactor. In the ozone injection reactor, oxidation of NO to NO2 took place with considerably higher efficiency compared to the hybrid reactor. The use of catalyst in the ozonation stage further improved the oxidation of NO2 to N2O5. The time-dependence effects of NO removal during plasma and ozone oxidation were explained by reactions between NO2 adsorbed on surface, with surface-bound NO3 and gas phase NO as the reaction product. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  8. FINAL REPORT on Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents

    SciTech Connect

    Chang H. Oh; Eung S. Kim; Hee C. NO; Nam Z. Cho

    2011-01-01

    The U.S. Department of Energy is performing research and development that focuses on key phenomena that are important during challenging scenarios that may occur in the Next Generation Nuclear Plant (NGNP)/Generation IV very high temperature reactor (VHTR). Phenomena Identification and Ranking studies to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important. Consequently, the development of advanced air ingress-related models and verification & validation are of very high priority for the NGNP Project. Following a loss of coolant and system depressurization incident, air ingress will occur through the break, leading to oxidation of the in-core graphite structure and fuel. This study indicates that depending on the location and the size of the pipe break, the air ingress phenomena are different. In an effort to estimate the proper safety margin, experimental data and tools, including accurate multidimensional thermal-hydraulic and reactor physics models, a burn-off model, and a fracture model are required. It will also require effective strategies to mitigate the effects of oxidation, eventually. This 3-year project (FY 2008–FY 2010) is focused on various issues related to the VHTR air-ingress accident, including (a) analytical and experimental study of air ingress caused by density-driven, stratified, countercurrent flow, (b) advanced graphite oxidation experiments, (c) experimental study of burn-off in the core bottom structures, (d) structural tests of the oxidized core bottom structures, (e) implementation of advanced models developed during the previous tasks into the GAMMA code, (f) full air ingress and oxidation mitigation analyses, (g) development of core neutronic models, (h) coupling of the core neutronic and thermal hydraulic models, and (i) verification and validation of the coupled models.

  9. Vitiated ethane oxidation in a high-pressure flow reactor

    SciTech Connect

    Walters, K.M.; Bowman, C.T.

    2009-10-15

    Vitiated combustion processes offer the potential to improve the thermodynamic efficiency in hydrocarbon-fueled combustion systems, providing a subsequent decrease in energy-specific CO{sub 2} emissions along with a decrease in the emission levels of nitrogen oxides (NO{sub x}) and particulate matter. The present work comprises an experimental and modeling study of vitiated ethane oxidation in a high-pressure flow reactor, with pressures of 1-6 bar, O{sub 2} mole fractions of 3.5-7.0%, temperatures of 1075-1100 K and 15-18 mole.% H{sub 2}O. Time-history measurements of species are used to characterize the overall rate of reaction and track the fuel-carbon through intermediate and product species. A one-dimensional mixing-reacting model that accounts for partial oxidation during reactant mixing is used in conjunction with a detailed kinetic mechanism. Changes in competing pathways due to variations in pressure and O{sub 2} mole fraction give rise to the complex pressure dependence seen in the experiments. (author)

  10. Oxidation rate of nuclear-grade graphite IG-110 in the kinetic regime for VHTR air ingress accident scenarios

    NASA Astrophysics Data System (ADS)

    Lee, Jo Jo; Ghosh, Tushar K.; Loyalka, Sudarshan K.

    2014-03-01

    The oxidation rates of nuclear-grade graphite IG-110 in the kinetically-controlled temperature regime of graphite oxidation were predicted and compared in Very High Temperature Reactor air ingress accident scenarios. The oxidative mass loss of graphite was measured thermogravimetrically from 873 to 1873 K in 100% air (21 mol%). The activation energy was found to be 222.07 kJ/mol, and the order of reaction with respect to oxygen concentration is 0.76. The surfaces of the samples were characterized by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Fourier Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy before and after oxidation. These results are compared with those available in the literature, and our recently reported results for NBG-18 nuclear-grade graphite using the same technique.

  11. Measurements of in-situ SOA Formation Using an Oxidation Flow Reactor at GoAmazon2014/5

    NASA Astrophysics Data System (ADS)

    Palm, B. B.; de Sá, S. S.; Campuzano Jost, P.; Day, D. A.; Hu, W.; Seco, R.; Park, J. H.; Guenther, A. B.; Kim, S.; Brito, J.; Wurm, F.; Artaxo, P.; Yee, L.; Isaacman-VanWertz, G. A.; Goldstein, A. H.; Souza, R. A. F. D.; Manzi, A. O.; Bustillos, J. O. V.; Tota, J.; Newburn, M. K.; Alexander, M. L. L.; Martin, S. T.; Brune, W. H.; Jimenez, J. L.

    2015-12-01

    During GoAmazon2014/5, ambient air was exposed to controlled concentrations of OH or O3 in-situ using an oxidation flow reactor (OFR). Oxidation ranged from hours-several weeks of aging. Oxidized air was sampled by several instruments (e.g., HR-AMS, ACSM, PTR-TOF-MS, SMPS, CCN) at both the T3 site (IOP1: Feb 1-Mar 31, 2014, and IOP2: Aug 15-Oct 15, 2014) and T2 site (between IOPs and into 2nd IOP). Oxidation of ambient air in the OFR led to significant and dynamic SOA formation. In general, more SOA was produced during the nighttime than daytime, and more in the dry season (IOP2) than wet season (IOP1). The maximum amount of SOA produced during nighttime from OH oxidation ranged from less than 1 µg/m3 to greater than 10 µg/m3. O3 oxidation of ambient air also led to SOA formation, although much less than from OH oxidation. Preliminary PMF factor analysis showed that the less-oxidized OOA (LO-OOA) factor was produced at up to several days OH aging, while at longer ages the more-oxidized OOA (MO-OOA) factor was formed and LO-OOA was depleted. HOA, BBOA, and IEPOX-SOA factors were not formed in the reactor, just depleted at high ages (though at different rates). More detailed PMF results will be presented. Variations in the amount of SOA formation often, but not always, correlated with measured gas-phase biogenic and/or anthropogenic SOA precursors (e.g., SV-TAG sesquiterpenes, PTR-TOFMS aromatics, isoprene, and monoterpenes). The SOA mass formed in the OFR was ~10x larger than could be explained by aerosol yields of measured primary VOCs, suggesting that most SOA was formed from intermediate sources such as S/IVOCs (e.g., VOC oxidation products or evaporated POA), consistent with previous OFR field and lab studies. To verify the SOA yields of VOCs under OFR experimental conditions, atmospherically-relevant concentrations of several VOCs were added individually into ambient air in the OFR and oxidized by OH or O3. SOA yields were similar to published chamber yields.

  12. [Experimental research on combined water and air backwashing reactor technology for biological activated carbon].

    PubMed

    Xie, Zhi-Gang; Qiu, Xue-Min; Zhao, Yan-Ling

    2012-01-01

    To proper control the backwashing process of biological activated carbon (BAC) reactor and improve the overall operation performance, the evaluative indexes such as backwashing wastewater turbidity, organic pollutants removal rate of pre and post-backwashing, and the variation of biomass and biological activity in carbon column are used to compare and analyze the effect of three different combined water and air backwashing methods on the operation of BAC reactor. The result shows that intermittent combined water and air backwashing method is most suitable to BAC reactor. The biological activaty obviously increases by 62.5% after intermittent combined water and air backwashing process. While, the biological activaty using the backwashing method of air plus water and the backwashing method of water and air compounded plus water washing increases by 55.6%, 38.5%, respectively. After backwashing 308h, the reactor recovered to its normal function after intermittent combined water and air backwashing process with the removal rate of UV254 reaching to 60.0%. The fulvic-like fluorescence peak of backwashing water are very weak, and are characterized by low-excitation wavelength tryptophan like (peak S) and high excitation wavelength of tryptophan (peak T), which are caused by the microbial debris washed down. The three-dimensional fluorescence spectra also show that microbial fragments are easy to be washed clean with intermittent combined water and air backwashing. PMID:22452199

  13. Initial oxidation of brass induced by humidified air

    PubMed Central

    Qiu, Ping; Leygraf, Christofer

    2011-01-01

    Complementary surface and near-surface analytical techniques have been used to explore a brass (Cu–20Zn) surface before, during, and after exposure in air at 90% relative humidity. Volta potential variations along the unexposed surface are attributed to variations in surface composition and resulted in an accelerated localized growth of ZnO and a retarded more uniform growth of an amorphous Cu2O-like oxide. After 3 days the duplex oxide has a total mass of 1.3 μg/cm2, with improved corrosion protective properties compared to the oxides grown on pure Cu or Zn. A schematic model for the duplex oxide growth on brass is presented. PMID:23471205

  14. Initial oxidation of brass induced by humidified air.

    PubMed

    Qiu, Ping; Leygraf, Christofer

    2011-11-15

    Complementary surface and near-surface analytical techniques have been used to explore a brass (Cu-20Zn) surface before, during, and after exposure in air at 90% relative humidity. Volta potential variations along the unexposed surface are attributed to variations in surface composition and resulted in an accelerated localized growth of ZnO and a retarded more uniform growth of an amorphous Cu2O-like oxide. After 3 days the duplex oxide has a total mass of 1.3 μg/cm(2), with improved corrosion protective properties compared to the oxides grown on pure Cu or Zn. A schematic model for the duplex oxide growth on brass is presented. PMID:23471205

  15. Air Ingress Accident in a High Temperature Reactor with Prismatic Fuel

    SciTech Connect

    Haque, H.; Brinkmann, G.

    2006-07-01

    In this paper, the safety behavior of the new generation high temperature reactors (HTRs) with prismatic fuels during air ingress accident conditions has been investigated. These reactors conceived primarily for the production of hydrogen, are characterized by their inherent safety features with respect to passive decay heat removal through conduction, radiation and natural convection. Air ingress is an HTR specific event. The potential threat posed by air ingress lies in the chemical reaction of oxygen with hot graphite at a temperature above 500 deg. C leading to reaction heat and graphite corrosion. A substantial amount of graphite burn-off can take place only if sufficient amount of air enters into the core. In order to better assess the phenomena of air ingress into the reactor, it is postulated that breaks are present above and below the reactor core and that unobstructed ingress of air through them is possible. It is obvious that the air ingress incident has to be preceded by a depressurization accident. For this hypothetical scenario the maximum possible air flow rate through the core resulting solely from the pressure losses in the core is determined as a function of the break cross sections exposed above and below the core. This paper demonstrates the thermal behavior of the ANTARES reactor (operating inlet/outlet temperatures 450/850 deg. C) for various air flow rates with respect to graphite burn-off and maximum temperatures of fuel and bottom reflector region. It indicates the limiting time at which the graphite layer of fuel will be completely burnt-off and the pellets exposed. (authors)

  16. Air quality impact analysis in support of the new production reactor environmental impact statement

    SciTech Connect

    Hadley, D L

    1991-04-01

    The Pacific Northwest Laboratory (PNL) conducted this air quality impact analysis for the US Department of Energy (DOE). The purpose of this work was to provide Argonne National Laboratory (ANL) with the required estimates of ground-level concentrations of five criteria air pollutants at the Hanford Site boundary from each of the stationary sources associated with the new production reactor (NPR) and its supporting facilities. The DOE proposes to provide new production capacity for the primary production of tritium and secondary production of plutonium to support the US nuclear weapons program. Three alternative reactor technologies are being considered by DOE: the light-water reactor, the low-temperature, heavy-water reactor, and the modular high-temperature, gas-cooled reactor. In this study, PNL provided estimates of the impacts of the proposed action on the ground-level concentration of the criteria air pollutants for each of the alternative technologies. The criteria pollutants were sulfur dioxide, nitrogen dioxide, carbon monoxide, total suspended particulates, and particulates with a diameter of less than 10 microns. Ground-level concentrations were estimated for the peak construction phase activities expected to occur in 1997 and for the operational phase activities beginning in the year 2000. Ground-level concentrations of the primary air pollutants were estimated to be well below any of the applicable national or state ambient air quality standards. 12 refs., 19 tabs.

  17. Surface-catalyzed air oxidation of hydrazines: Environmental chamber studies

    NASA Technical Reports Server (NTRS)

    Kilduff, Jan E.; Davis, Dennis D.; Koontz, Steven L.

    1988-01-01

    The surface-catalyzed air oxidation reactions of fuel hydrazines were studied in a 6500-liter fluorocarbon-film chamber at 80 to 100 ppm concentrations. First-order rate constants for the reactions catalyzed by aluminum, water-damaged aluminum (Al/Al2O3), stainless steel 304L, galvanized steel and titanium plates with surface areas of 2 to 24 sq m were determined. With 23.8 sq m of Al/Al2O3 the surface-catalyzed air oxidation of hydrazine had a half-life of 2 hours, diimide (N2H2) was observed as an intermediate and traces of ammonia were present in the final product mixture. The Al/Al2O3 catalyzed oxidation of monomethylhydrazine yielded methyldiazine (HN = NCH3) as an intermediate and traces of methanol. Unsymmetrical dimethylhydrazine gave no detectable products. The relative reactivities of hydrazine, MMH and UDMH were 130 : 7.3 : 1.0, respectively. The rate constants for Al/Al2O3-catalyzed oxidation of hydrazine and MMH were proportional to the square of the surface area of the plates. Mechanisms for the surface-catalyzed oxidation of hydrazine and diimide and the formation of ammonia are proposed.

  18. Controlled CO preferential oxidation

    DOEpatents

    Meltser, M.A.; Hoch, M.M.

    1997-06-10

    Method is described for controlling the supply of air to a PROX (PReferential OXidation for CO cleanup) reactor for the preferential oxidation in the presence of hydrogen wherein the concentration of the hydrogen entering and exiting the PROX reactor is monitored, the difference there between correlated to the amount of air needed to minimize such difference, and based thereon the air supply to the PROX reactor adjusted to provide such amount and minimize such difference. 2 figs.

  19. A long life zinc oxide-titanium oxide sorbent for moving bed reactors

    SciTech Connect

    Copeland, R.; Cesario, M.; Dubovik, M.; Feinberg, D.; Windecker, B.; Yang, J.

    1996-12-31

    Coal Fired Gasifier Combined Cycles (GCCs) have both high efficiency and very low emissions. GCCs are in critical need of a method to remove the H{sub 2}S produced from the sulfur in the coal from the hot gases. There has been extensive research on hot gas clean-up systems, focused on the use of a zinc oxide based sorbent (e.g., zinc titanate). However, the previous sorbents show significant losses in sulfur capacity with cycling. TDA Research, Inc. recently increased the zinc oxide content and sulfur loadings while simultaneously improving the attrition resistance. The improved fabrication method produces long life, low cost sorbent containing zinc oxide. The authors are currently testing sorbents at conditions simulating a moving bed reactor for GCC [i.e., 20 atm, 482 C (900 F) to 538 C (1,000 F), and 1% H{sub 2}S].

  20. Biodegradation of air-oxidized Illinois No. 6 coal

    SciTech Connect

    Linehan, J.C.; Fredrickson, J.K.; Wilson, B.W.; Bean, R.M.; Stewart, D.L.; Thomas, B.L.; Campbell, J.A.; Franz, J.A.

    1988-09-01

    We have found that Illinois No. 6 coal, after an air-oxidation pretreatment, can be substantially biodegraded by Penicillium sp. to a product largely soluble in dilute base. It is the purpose of this paper to describe the chemical nature of the biotreated Illinois No. 6 coal and to compare it with the corresponding material from leonardite biosolubilization. 12 refs., 7 figs., 3 tabs.

  1. Cyclic Oxidation of High-Temperature Alloy Wires in Air

    NASA Technical Reports Server (NTRS)

    Reigel, Marissa M.

    2004-01-01

    High-temperature alloy wires are proposed for use in seal applications for future re-useable space vehicles. These alloys offer the potential for improved wear resistance of the seals. The wires must withstand the high temperature environments the seals are subjected to as well as maintain their oxidation resistance during the heating and cooling cycles of vehicle re-entry. To model this, the wires were subjected to cyclic oxidation in stagnant air. of this layer formation is dependent on temperature. Slow growing oxides such as chromia and alumina are desirable. Once the oxide is formed it can prevent the metal from further reacting with its environment. Cyclic oxidation models the changes in temperature these wires will undergo in application. Cycling the temperature introduces thermal stresses which can cause the oxide layer to break off. Re-growth of the oxide layer consumes more metal and therefore reduces the properties and durability of the material. were used for cyclic oxidation testing. The baseline material, Haynes 188, has a Co base and is a chromia former while the other two alloys, Kanthal A1 and PM2000, both have a Fe base and are alumina formers. Haynes 188 and Kanthal A1 wires are 250 pm in diameter and PM2000 wires are 150 pm in diameter. The coiled wire has a total surface area of 3 to 5 sq cm. The wires were oxidized for 11 cycles at 1204 C, each cycle containing a 1 hour heating time and a minimum 20 minute cooling time. Weights were taken between cycles. After 11 cycles, one wire of each composition was removed for analysis. The other wire continued testing for 70 cycles. Post-test analysis includes X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) for phase identification and morphology.

  2. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, L.; Ruka, R.J.; Singhal, S.C.

    1999-08-03

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO{sub 3}. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell. 3 figs.

  3. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, Lewis; Ruka, Roswell J.; Singhal, Subhash C.

    1999-01-01

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell.

  4. Air Monitoring of Emissions from the Fukushima Daiichi Reactor

    SciTech Connect

    McNaughton, Michael; Allen, Shannon P.; Archuleta, Debra C.; Brock, Burgandy; Coronado, Melissa A.; Dewart, Jean M.; Eisele, William F. Jr.; Fuehne, David P.; Gadd, Milan S.; Green, Andrew A.; Lujan, Joan J.; MacDonell, Carolyn; Whicker, Jeffrey J.

    2012-06-12

    In response to the disasters in Japan on March 11, 2011, and the subsequent emissions from Fukushima-Daiichi, we monitored the air near Los Alamos using four air-monitoring systems: the standard AIRNET samplers, the standard rad-NESHAP samplers, the NEWNET system, and high-volume air samplers. Each of these systems has advantages and disadvantages. In combination, they provide a comprehensive set of measurements of airborne radionuclides near Los Alamos during the weeks following March 11. We report air-monitoring measurements of the fission products released from the Fukushima-Daiichi nuclear-power-plant accident in 2011. Clear gamma-spectrometry peaks were observed from Cs-134, Cs-136, Cs-137, I-131, I132, Te-132, and Te-129m. These data, together with measurements of other radionuclides, are adequate for an assessment and assure us that radionuclides from Fukushima Daiichi did not present a threat to human health at or near Los Alamos. The data demonstrate the capabilities of the Los Alamos air-monitoring systems.

  5. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed Reactor

    SciTech Connect

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-15

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  6. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: kinetics and biodegradability enhancement.

    PubMed

    Suárez-Ojeda, María Eugenia; Kim, Jungkwon; Carrera, Julián; Metcalfe, Ian S; Font, Josep

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15 bar of oxygen partial pressure (P(O2)) and at 180, 200 and 220 degrees C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P(O2) were 140-160 degrees C and 2-9 bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160 degrees C and 2 bar of P(O2), which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD(RB)) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture. PMID:17363148

  7. Supported noble metal catalysts in the catalytic wet air oxidation of industrial wastewaters and sewage sludges.

    PubMed

    Besson, M; Descorme, C; Bernardi, M; Gallezot, P; di Gregorio, F; Grosjean, N; Minh, D Pham; Pintar, A

    2010-12-01

    This paper reviews some catalytic wet air oxidation (CWAO) investigations of industrial wastewaters over platinum and ruthenium catalysts supported on TiO2 and ZrO2 formulated to be active and resistant to leaching, with particular focus on the stability of the catalyst. Catalyst recycling experiments were performed in batch reactors and long-term stability tests were conducted in trickle-bed reactors. The catalyst did not leach upon treatment of Kraft bleaching plant and olive oil mill effluents, and could be either recycled or used for long periods of time in continuous reactors. Conversely, these catalysts were rapidly leached when used to treat effluents from the production of polymeric membranes containing N,N-dimethylformamide. The intermediate formation of amines, such as dimethylamine and methylamine with a high complexing capacity for the metal, was shown to be responsible for the metal leaching. These heterogeneous catalysts also deactivated upon CWAO of sewage sludges due to the adsorption of the solid organic matter. Pre-sonication of the sludge to disintegrate the flocs and improve solubility was inefficient. PMID:21214003

  8. Use of Beryllium and Beryllium Oxide in Space Reactors

    SciTech Connect

    Snead, L. L.; Zinkle, S. J.

    2005-02-06

    Beryllium and beryllium oxide are attractive candidate materials for neutron reflector application in space reactors due to their beneficial combination of low density and high neutron moderation and reflection capabilities. Drawbacks to their use include the expense of working with toxic materials, a limited industrial infrastructure, and material properties that are challenging in the non-irradiated state and seriously degrade under neutron irradiation. As an example of neutron effects, mechanical properties degrade under relevant conditions to the point where encasement in structural alloys is necessary. Such measures are required if neutron fluence exceeds {approx}1x1024 n/m2 (E>0.1 MeV). At high temperatures (>500 deg. C for Be and >600 deg. C for BeO), irradiation-induced swelling may also limit the maximum allowable dose without additional engineering measures. Significant volumetric swelling (>5%) can occur in these materials during neutron irradiation at elevated temperatures for neutron fluences above 1x1025 n/m2. This paper will review Be and BeO fabrication considerations, and summarize the effects of neutron irradiation on material properties.

  9. PBF Reactor Building (PER620) basement. Camera facing north. Cooling air ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PBF Reactor Building (PER-620) basement. Camera facing north. Cooling air compressor for control rods; inner cooler and after cooler; associated piping. Photographer: John Capek. Date: August 21, 1970. INEEL negative no. 70-3493 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  10. Sulfide-oxidizing bacteria establishment in an innovative microaerobic reactor with an internal silicone membrane for sulfur recovery from wastewater.

    PubMed

    Valdés, F; Camiloti, P R; Rodriguez, R P; Delforno, T P; Carrillo-Reyes, J; Zaiat, M; Jeison, D

    2016-06-01

    A novel bioreactor, employing a silicone membrane for microaeration, was studied for partial sulfide oxidation to elemental sulfur. The objective of this study was to assess the feasibility of using an internal silicone membrane reactor (ISMR) to treat dissolved sulfide and to characterize its microbial community. The ISMR is an effective system to eliminate sulfide produced in anaerobic reactors. Sulfide removal efficiencies reached 96 % in a combined anaerobic/microaerobic reactor and significant sulfate production did not occur. The oxygen transfer was strongly influenced by air pressure and flow. Pyrosequencing analysis indicated various sulfide-oxidizing bacteria (SOB) affiliated to the species Acidithiobacillus thiooxidans, Sulfuricurvum kujiense and Pseudomonas stutzeri attached to the membrane and also indicated similarity between the biomass deposited on the membrane wall and the biomass drawn from the material support, supported the establishment of SOB in an anaerobic sludge under microaerobic conditions. Furthermore, these results showed that the reactor configuration can develop SOB under microaerobic conditions and can improve and reestablish the sulfide conversion to elemental sulfur. PMID:27003697

  11. FY-09 Report: Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents

    SciTech Connect

    Chang H. Oh; Eung S. Kim

    2009-12-01

    The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in the Next Generation Nuclear Plant (NGNP)/Gen-IV very high temperature reactor (VHTR). Phenomena Identification and Ranking Studies to date have identified that an air ingress event following on the heels of a VHTR depressurization is a very important incident. Consequently, the development of advanced air ingress-related models and verification and validation data are a very high priority for the NGNP Project. Following a loss of coolant and system depressurization incident, air will enter the core through the break, leading to oxidation of the in-core graphite structure and fuel. If this accident occurs, the oxidation will accelerate heat-up of the bottom reflector and the reactor core and will eventually cause the release of fission products. The potential collapse of the core bottom structures causing the release of CO and fission products is one of the concerns. Therefore, experimental validation with the analytical model and computational fluid dynamic (CFD) model developed in this study is very important. Estimating the proper safety margin will require experimental data and tools, including accurate multidimensional thermal-hydraulic and reactor physics models, a burn-off model, and a fracture model. It will also require effective strategies to mitigate the effects of oxidation. The results from this research will provide crucial inputs to the INL NGNP/VHTR Methods Research and Development project. The second year of this three-year project (FY-08 to FY-10) was focused on (a) the analytical, CFD, and experimental study of air ingress caused by density-driven, stratified, countercurrent flow; (b) advanced graphite oxidation experiments and modeling; (c) experimental study of burn-off in the core bottom structures, (d) implementation of advanced

  12. Exergy parametric study of carbon monoxide oxidation in moist air

    NASA Astrophysics Data System (ADS)

    Souidi, Ferhat; Benmalek, Toufik; Yesaad, Billel; Baik, Mouloud

    2015-12-01

    This study aims to analyze the oxidation of carbon monoxide in moist air from the second thermodynamic law aspect. A mathematical model of laminar premixed flame in a stagnation point flow has been achieved by numerical solution of the boundary layer equation using a self-made code. The chemical kinetic mechanism for flameless combustion of fuel, which is a mixture of carbon monoxide, oxygen, and water vapor, is modeled by 34 elementary reactions that incorporate (09) nine chemical species: CO, O, CO2, O2, H2O, H, H2, HO2, and OH. The salient point is that for all the parameters we considered, the exergy of the process is completely destroyed by irreversibilities. From the chemical viewpoint, the OH radical plays an essential role in CO oxidation. This latter point has already been mentioned by previous investigators.

  13. Air-lift reactor system for the treatment of waste-gas-containing monochlorobenzene.

    PubMed

    Joshi, Pradnya R; Deshmukh, Sharvari C; Morone, Amruta P; Kanade, Gajanan; Pandey, R A

    2013-01-01

    An air-lift bioreactor (ALR) system, applied for the treatment of waste-gas-containing monochlorobenzene (MCB) was seeded with pure culture of Acinetobacter calcoaceticus, isolated from soil as a starter seed. It was found that MCB was biologically converted to chloride as chloride was mineralized in the ALR. After the built up of the biomass in the ALR, the reactor parameters which have major influence on the removal efficiency and elimination capacity were studied using response surface methodology. The data generated by running the reactor for 150 days at varying conditions were fed to the model with a target to obtain the removal efficiency above 95% and the elimination capacity greater than 60%. The data analysis indicated that inlet loading was the major parameter affecting the elimination capacity and removal efficiency of >95%. The reactor when operated at optimized conditions resulted in enhanced performance of the reactor. PMID:24617061

  14. Electrocatalytic oxidation of n-propanol to produce propionic acid using an electrocatalytic membrane reactor.

    PubMed

    Li, Jiao; Li, Jianxin; Wang, Hong; Cheng, Bowen; He, Benqiao; Yan, Feng; Yang, Yang; Guo, Wenshan; Ngo, Huu Hao

    2013-05-18

    An electrocatalytic membrane reactor assembled using a nano-MnO2 loading microporous Ti membrane as an anode and a tubular stainless steel as a cathode was used to oxidize n-propanol to produce propionic acid. The high efficiency and selectivity obtained is related to the synergistic effect between the reaction and separation in the reactor. PMID:23572114

  15. Performance Characterization of a Prototype Ultra-Short Channel Monolith Catalytic Reactor for Air Quality Control Applications

    NASA Technical Reports Server (NTRS)

    Perry, J. L.; Tomes, K. M.; Roychoudhury, S.; Tatara, J. D.

    2005-01-01

    Contaminated air and process gases, whether in a crewed spacecraft cabin atmosphere, the working volume of a microgravity science or ground-based laboratory experiment facility, or the exhaust from an automobile, are pervasive problems that ultimately effect human health, performance, and well-being. The need for highly-effective, economical decontamination processes spans a wide range of terrestrial and space flight applications. Adsorption processes are used widely for process gas decontamination. Most industrial packed bed adsorption processes use activated carbon because it is cheap and highly effective. Once saturated, however, the adsorbent is a concentrated source of contaminants. Industrial applications either dump or regenerate the activated carbon. Regeneration may be accomplished in-situ or at an off-site location. In either case, concentrated contaminated waste streams must be handled appropriately to minimize environmental impact. As economic and regulatory forces drive toward minimizing waste and environmental impact, thermal catalytic oxidation is becoming more attractive. Through novel reactor and catalyst design, more complete contaminant destruction and greater resistance to poisoning can achieved leading to less waste handling, process down-time, and maintenance. Performance of a prototype thermal catalytic reactor, based on ultra-short channel monolith (USCM) catalyst substrate design, under a variety of process flow and contaminant loading conditions is discussed. The experimental results are evaluated against present and future air quality control and process gas purification processes used on board crewed spacecraft.

  16. Domestic wastewater treatment by a submerged MBR (membrane bio-reactor) with enhanced air sparging.

    PubMed

    Chang, I S; Judd, S J

    2003-01-01

    The air sparging technique has been recognised as an effective way to control membrane fouling. However, its application to a submerged MBR (Membrane Bio-Reactor) has not yet been reported. This paper deals with the performances of air sparging on a submerged MBR for wastewater treatment. Two kinds of air sparging techniques were used respectively. First, air is injected into the membrane tube channels so that mixed liquor can circulate in the bioreactor (air-lift mode). Second, a periodic air-jet into the membrane tube is introduced (air-jet mode). Their applicability was evaluated with a series of lab-scale experiments using domestic wastewater. The flux increased from 23 to 33 l m(-2) h(-1) (43% enhancement) when air was injected for the air-lift module. But further increase of flux was not observed as the gas flow increased. The Rc/(Rc+Rf), ratio of cake resistance (Rc) to sum of Rc and Rf (internal fouling resistance), was 23%, indicating that the Rc is not the predominant resistance unlike other MBR studies. It showed that the cake layer was removed sufficiently due to the air injection. Thus, an increase of airflow could not affect the flux performance. The air-jet module suffered from a clogging problem with accumulated sludge inside the lumen. Because the air-jet module has characteristics of dead end filtration, a periodic air-jet was not enough to blast all the accumulated sludge out. But flux was greater than in the air-lift module if the clogging was prevented by an appropriate cleaning regime such as periodical backwashing. PMID:12926682

  17. Ammonia-oxidizing microbial communities in reactors with efficient nitrification at low-dissolved oxygen

    PubMed Central

    Fitzgerald, Colin M.; Camejo, Pamela; Oshlag, J. Zachary; Noguera, Daniel R.

    2015-01-01

    Ammonia-oxidizing microbial communities involved in ammonia oxidation under low dissolved oxygen (DO) conditions (<0.3 mg/L) were investigated using chemostat reactors. One lab-scale reactor (NS_LowDO) was seeded with sludge from a full-scale wastewater treatment plant (WWTP) not adapted to low-DO nitrification, while a second reactor (JP_LowDO) was seeded with sludge from a full-scale WWTP already achieving low-DO nitrifiaction. The experimental evidence from quantitative PCR, rDNA tag pyrosequencing, and fluorescence in situ hybridization (FISH) suggested that ammonia-oxidizing bacteria (AOB) in the Nitrosomonas genus were responsible for low-DO nitrification in the NS_LowDO reactor, whereas in the JP_LowDO reactor nitrification was not associated with any known ammonia-oxidizing prokaryote. Neither reactor had a significant population of ammonia-oxidizing archaea (AOA) or anaerobic ammonium oxidation (anammox) organisms. Organisms isolated from JP_LowDO were capable of autotrophic and heterotrophic ammonia utilization, albeit without stoichiometric accumulation of nitrite or nitrate. Based on the experimental evidence we propose that Pseudomonas, Xanthomonadaceae, Rhodococcus, and Sphingomonas are involved in nitrification under low-DO conditions. PMID:25506762

  18. 40 CFR 50.17 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.17 Section 50.17 Protection of Environment ENVIRONMENTAL....17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75...

  19. 40 CFR 50.5 - National secondary ambient air quality standard for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... standard for sulfur oxides (sulfur dioxide). 50.5 Section 50.5 Protection of Environment ENVIRONMENTAL....5 National secondary ambient air quality standard for sulfur oxides (sulfur dioxide). (a) The level... than 0.05 ppm shall be rounded up). (b) Sulfur oxides shall be measured in the ambient air as...

  20. 40 CFR 50.4 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.4 Section 50.4 Protection of Environment ENVIRONMENTAL....4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level...). (c) Sulfur oxides shall be measured in the ambient air as sulfur dioxide by the reference...

  1. 40 CFR 50.17 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.17 Section 50.17 Protection of Environment ENVIRONMENTAL....17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75...

  2. 40 CFR 50.17 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.17 Section 50.17 Protection of Environment ENVIRONMENTAL....17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75...

  3. 40 CFR 50.17 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.17 Section 50.17 Protection of Environment ENVIRONMENTAL....17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75...

  4. 40 CFR 50.4 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.4 Section 50.4 Protection of Environment ENVIRONMENTAL....4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level...). (c) Sulfur oxides shall be measured in the ambient air as sulfur dioxide by the reference...

  5. 40 CFR 50.5 - National secondary ambient air quality standard for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... standard for sulfur oxides (sulfur dioxide). 50.5 Section 50.5 Protection of Environment ENVIRONMENTAL....5 National secondary ambient air quality standard for sulfur oxides (sulfur dioxide). (a) The level... than 0.05 ppm shall be rounded up). (b) Sulfur oxides shall be measured in the ambient air as...

  6. 40 CFR 50.5 - National secondary ambient air quality standard for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... standard for sulfur oxides (sulfur dioxide). 50.5 Section 50.5 Protection of Environment ENVIRONMENTAL....5 National secondary ambient air quality standard for sulfur oxides (sulfur dioxide). (a) The level... than 0.05 ppm shall be rounded up). (b) Sulfur oxides shall be measured in the ambient air as...

  7. 40 CFR 50.4 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.4 Section 50.4 Protection of Environment ENVIRONMENTAL....4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level...). (c) Sulfur oxides shall be measured in the ambient air as sulfur dioxide by the reference...

  8. 40 CFR 50.17 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.17 Section 50.17 Protection of Environment ENVIRONMENTAL....17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75...

  9. 40 CFR 50.5 - National secondary ambient air quality standard for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... standard for sulfur oxides (sulfur dioxide). 50.5 Section 50.5 Protection of Environment ENVIRONMENTAL....5 National secondary ambient air quality standard for sulfur oxides (sulfur dioxide). (a) The level... than 0.05 ppm shall be rounded up). (b) Sulfur oxides shall be measured in the ambient air as...

  10. 40 CFR 50.4 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.4 Section 50.4 Protection of Environment ENVIRONMENTAL....4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level...). (c) Sulfur oxides shall be measured in the ambient air as sulfur dioxide by the reference...

  11. USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE

    SciTech Connect

    Adu-Wusu, K; Daniel McCabe, D; Bill Wilmarth, B

    2007-04-04

    A bench-scale feasibility study on the use of a Wet Air Oxidation (WAO) process to destroy a slurry laden with tetraphenylborate (TPB) compounds has been undertaken. WAO is an aqueous phase process in which soluble and/or insoluble waste constituents are oxidized using oxygen or oxygen in air at elevated temperatures and pressures ranging from 150 C and 1 MPa to 320 C and 22 MPa. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). Test results indicate WAO is a feasible process for destroying TPB, its primary daughter products [triphenylborane (3PB), diphenylborinic acid (2PB), and phenylboronic acid (1PB)], phenol, and most of the biphenyl byproduct. The required conditions are a temperature of 300 C, a reaction time of 3 hours, 1:1 feed slurry dilution with 2M NaOH solution, the addition of CuSO{sub 4}.5H{sub 2}O solution (500 mg/L Cu) as catalyst, and the addition of 2000 mL/L of antifoam. However, for the destruction of TPB, its daughter compounds (3PB, 2PB, and 1PB), and phenol without consideration for biphenyl destruction, less severe conditions (280 C and 1-hour reaction time with similar remaining above conditions) are adequate.

  12. Oxidative Allylic Esterification of Alkenes by Cooperative Selenium-Catalysis Using Air as the Sole Oxidant.

    PubMed

    Ortgies, Stefan; Depken, Christian; Breder, Alexander

    2016-06-17

    A new metal-free catalysis protocol for the oxidative coupling of nonactivated alkenes with simple carboxylic acids has been established. This method is predicated on the cooperative interaction of a diselane and a photoredox catalyst, which allows for the use of ambient air or pure O2 as the terminal oxidant. Under the title conditions, a range of both functionalized and nonfunctionalized alkenes can be readily converted into the corresponding allylic ester products with good yields (up to 89%) and excellent regioselectivity as well as good functional group tolerance. PMID:27257803

  13. Alveolar macrophage cytokine response to air pollution particles: Oxidant mechanisms

    SciTech Connect

    Imrich, Amy; Ning Yaoyu; Lawrence, Joy; Coull, Brent; Gitin, Elena; Knutson, Mitchell; Kobzik, Lester . E-mail: lkobzik@hsph.harvard.edu

    2007-02-01

    Alveolar macrophages (AMs) primed with LPS and treated with concentrated ambient air particles (CAPs) showed enhanced release of tumor necrosis factor (TNF) and provide an in vitro model for the amplified effects of air pollution particles seen in people with preexisting lung disease. To investigate the mechanism(s) by which CAPs mediate TNF release in primed rat AMs, we first tested the effect of a panel of antioxidants. N-Acetyl-L-cysteine (20 mM), dimethyl thiourea (20 mM) and catalase (5 {mu}M) significantly inhibited TNF release by primed AMs incubated with CAPs. Conversely, when LPS-primed AMs were treated with CAPs in the presence of exogenous oxidants (H{sub 2}O{sub 2} generated by glucose oxidase, 10 {mu}M/h), TNF release and cell toxicity was significantly increased. The soluble fraction of CAPs suspensions caused most of the increased bioactivity in the presence of exogenous H{sub 2}O{sub 2}. The metal chelator deferoxamine (DFO) strongly inhibited the interaction of the soluble fraction with H{sub 2}O{sub 2} but had no effect on the bioactivity of the insoluble CAPs fraction. We conclude that CAPs can mediate their effects in primed AMs by acting on oxidant-sensitive cytokine release in at least two distinct ways. In the primed cell, insoluble components of PM mediate enhanced TNF production that is H{sub 2}O{sub 2}-dependent (catalase-sensitive) yet independent of iron (DFO-insensitive). In the presence of exogenous H{sub 2}O{sub 2} released by AMs, PMNs, or other lung cells within an inflamed alveolar milieu, soluble iron released from air particles can also mediate cytokine release and cell toxicity.

  14. Alveolar macrophage cytokine response to air pollution particles: oxidant mechanisms

    PubMed Central

    Imrich, Amy; Ning, YaoYu; Lawrence, Joy; Coull, Brent; Gitin, Elena; Knutson, Mitchell; Kobzik, Lester

    2007-01-01

    Alveolar macrophages (AMs) primed with LPS and treated with concentrated ambient air particles (CAPs) showed enhanced release of tumor necrosis factor (TNF) and provide an in vitro model for the amplified effects of air pollution particles seen in people with preexisting lung disease. To investigate the mechanism(s) by which CAPs mediate TNF release in primed rat AMs, we first tested the effect of a panel of antioxidants. N-acetyl cysteine (20mM), dimethyl thiourea (20 mM) and catalase (5 uM) significantly inhibited TNF release by primed AMs incubated with CAPs. Conversely, when LPS-primed AMs were treated with CAPs in the presence of exogenous oxidants (H2O2 generated by glucose oxidase, 10 uM/hr), TNF release and cell toxicity was significantly increased. The soluble fraction of CAPs suspensions caused most of the increased bioactivity in the presence of exogenous H2O2. The metal chelator deferoxamine (DFO) strongly inhibited the interaction of the soluble fraction with H2O2 but had no effect on the bioactivity of the insoluble CAPs fraction. We conclude that CAPs can mediate their effects in primed AMs by acting on oxidant-sensitive cytokine release in at least two distinct ways. In the primed cell, insoluble components of PM mediate enhanced TNF production that is H2O2-dependent (catalase-sensitive) yet independent of iron (DFO-insensitive). In the presence of exogenous H2O2 released by AMs, PMNs, or other lung cells within an inflamed alveolar milieu, soluble iron released from air particles can also mediate cytokine release and cell toxicity. PMID:17222881

  15. Modeling the radical chemistry in an oxidation flow reactor: radical formation and recycling, sensitivities, and the OH exposure estimation equation.

    PubMed

    Li, Rui; Palm, Brett B; Ortega, Amber M; Hlywiak, James; Hu, Weiwei; Peng, Zhe; Day, Douglas A; Knote, Christoph; Brune, William H; de Gouw, Joost A; Jimenez, Jose L

    2015-05-14

    Oxidation flow reactors (OFRs) containing low-pressure mercury (Hg) lamps that emit UV light at both 185 and 254 nm ("OFR185") to generate OH radicals and O3 are used in many areas of atmospheric science and in pollution control devices. The widely used potential aerosol mass (PAM) OFR was designed for studies on the formation and oxidation of secondary organic aerosols (SOA), allowing for a wide range of oxidant exposures and short experiment duration with reduced wall loss effects. Although fundamental photochemical and kinetic data applicable to these reactors are available, the radical chemistry and its sensitivities have not been modeled in detail before; thus, experimental verification of our understanding of this chemistry has been very limited. To better understand the chemistry in the OFR185, a model has been developed to simulate the formation, recycling, and destruction of radicals and to allow the quantification of OH exposure (OHexp) in the reactor and its sensitivities. The model outputs of OHexp were evaluated against laboratory calibration experiments by estimating OHexp from trace gas removal and were shown to agree within a factor of 2. A sensitivity study was performed to characterize the dependence of the OHexp, HO2/OH ratio, and O3 and H2O2 output concentrations on reactor parameters. OHexp is strongly affected by the UV photon flux, absolute humidity, reactor residence time, and the OH reactivity (OHR) of the sampled air, and more weakly by pressure and temperature. OHexp can be strongly suppressed by high OHR, especially under low UV light conditions. A OHexp estimation equation as a function of easily measurable quantities was shown to reproduce model results within 10% (average absolute value of the relative errors) over the whole operating range of the reactor. OHexp from the estimation equation was compared with measurements in several field campaigns and shows agreement within a factor of 3. The improved understanding of the OFR185 and

  16. Air Flow and Pressure Drop Measurements Across Porous Oxides

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.; Cuy, Michael D.; Werner, Roger A.

    2008-01-01

    This report summarizes the results of air flow tests across eight porous, open cell ceramic oxide samples. During ceramic specimen processing, the porosity was formed using the sacrificial template technique, with two different sizes of polystyrene beads used for the template. The samples were initially supplied with thicknesses ranging from 0.14 to 0.20 in. (0.35 to 0.50 cm) and nonuniform backside morphology (some areas dense, some porous). Samples were therefore ground to a thickness of 0.12 to 0.14 in. (0.30 to 0.35 cm) using dry 120 grit SiC paper. Pressure drop versus air flow is reported. Comparisons of samples with thickness variations are made, as are pressure drop estimates. As the density of the ceramic material increases the maximum corrected flow decreases rapidly. Future sample sets should be supplied with samples of similar thickness and having uniform surface morphology. This would allow a more consistent determination of air flow versus processing parameters and the resulting porosity size and distribution.

  17. Computational Fluid Dynamics Analyses on Very High Temperature Reactor Air Ingress

    SciTech Connect

    Chang H Oh; Eung S. Kim; Richard Schultz; David Petti; Hyung S. Kang

    2009-07-01

    A preliminary computational fluid dynamics (CFD) analysis was performed to understand density-gradient-induced stratified flow in a Very High Temperature Reactor (VHTR) air-ingress accident. Various parameters were taken into consideration, including turbulence model, core temperature, initial air mole-fraction, and flow resistance in the core. The gas turbine modular helium reactor (GT-MHR) 600 MWt was selected as the reference reactor and it was simplified to be 2-D geometry in modeling. The core and the lower plenum were assumed to be porous bodies. Following the preliminary CFD results, the analysis of the air-ingress accident has been performed by two different codes: GAMMA code (system analysis code, Oh et al. 2006) and FLUENT CFD code (Fluent 2007). Eventually, the analysis results showed that the actual onset time of natural convection (~160 sec) would be significantly earlier than the previous predictions (~150 hours) calculated based on the molecular diffusion air-ingress mechanism. This leads to the conclusion that the consequences of this accident will be much more serious than previously expected.

  18. A Theoretical Investigation of Oxidation Efficiency of a Volatile Removal Assembly Reactor Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Guo, Boyun

    2005-01-01

    Volatile Removal Assembly (VRA) is a subsystem of the Closed Environment Life Support System (CELSS) installed in the International Space Station. It is used for removing contaminants (volatile organics) in the wastewater produced by the space station crews. The major contaminants are formic acid, ethanol, and propylene glycol. The VRA contains a slim packbed reactor (3.5 cm diameter and four 28 cm long tubes in series) to perform catalyst oxidation of wastewater at elevated pressure and temperature under microgravity conditions. In the reactor, the contaminants are burned with oxygen gas (O2) to form water and carbon dioxide (CO2) that dissolves in the water stream. Optimal design of the reactor requires a thorough understanding about how the reactor performs under microgravity conditions. The objective of this study was to develop a mathematical model to interpret experimental data obtained from normal and microgravity conditions, and to predict the performance of VRA reactor under microgravity conditions. Catalyst oxidation kinetics and the total oxygen-water contact area control the efficiency of catalyst oxidation for mass transfer, which depends on oxygen gas holdup and distribution in the reactor. The process involves bubbly flow in porous media with chemical reactions in microgravity environment. This presents a unique problem in fluid dynamics that has not been studied. Guo et al. (2004) developed a mathematical model that predicts oxygen holdup in the VRA reactor. No mathematical model has been found in the literature that can be used to predict the efficiency of catalyst oxidation under microgravity conditions.

  19. Selective oxidation of n-butane to maleic anhydride; 4. Recycle reactor studies

    SciTech Connect

    Bej, S.K.; Rao, M.S. )

    1992-09-01

    This paper reports on the selective oxidation of n-butane to aleic anhydride which has been modeled using recycle reactor data. Two different types of models have been tested based on the concept that V[sup 5+] is the selective site and V[sup 4+] is the nonselective site and vice versa. Recycle reactor data support the model which assumes V[sup 5+] as the selective site as the selective site and V[sup 4+] as the nonselective site. The model has been used to predict the performance of an integral reactor and tested with experimental integral reactor data.

  20. OPERATION OF FUSION REACTORS IN ONE ATMOSPHERE OF AIR INSTEAD OF VACUUM SYSTEMS

    SciTech Connect

    Roth, J. Reece

    2009-07-26

    Engineering design studies of both magnetic and inertial fusion power plants have assumed that the plasma will undergo fusion reactions in a vacuum environment. Operation under vacuum requires an expensive additional major system for the reactor-a vacuum vessel with vacuum pumping, and raises the possibility of sudden unplanned outages if the vacuum containment is breached. It would be desirable in many respects if fusion reactors could be made to operate at one atmosphere with air surrounding the plasma, thus eliminating the requirement of a pressure vessel and vacuum pumping. This would have obvious economic, reliability, and engineering advantages for currently envisaged power plant reactors; it would make possible forms of reactor control not possible under vacuum conditions (i.e. adiabatic compression of the fusion plasma by increasing the pressure of surrounding gas); it would allow reactors used as aircraft engines to operate as turbojets or ramjets in the atmosphere, and it would allow reactors used as fusion rockets to take off from the surface of the earth instead of low earth orbit.

  1. Composition of air pollution particles modifies oxidative stress in cells, tissues, and living systems

    EPA Science Inventory

    Epidemiological studies demonstrate an association between increased levels of ambient air pollution particles and human morbidity and mortality. Production of oxidants, either directly by the air pollution particles or by the host response to the particles, appears to be fundame...

  2. 40 CFR 50.4 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 2 2010-07-01 2010-07-01 false National primary ambient air quality... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS § 50.4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). Link to...

  3. AIR QUALITY CRITERIA FOR PARTICULATE MATTER AND SULFUR OXIDES (Final, 1982)

    EPA Science Inventory

    Particulate matter and sulfur oxides are two of six major air pollutants regulated by National Ambient Air Quality Standards (NAAQS) under the U.S. Clean Air Act. As mandated by the Clean Air Act, the U.S. Environmental Protection Agency (EPA) must periodically review the scienti...

  4. In-Reactor Oxidation of Zircaloy-4 Under Low Water Vapor Pressures

    SciTech Connect

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin; Longhurst, Glen

    2015-01-01

    Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330° and 370°C). Data from these tests will be used to support fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr-4 over the specified range of test conditions. Comparisons between in- and ex- reactor test results were performed to evaluate the influence of irradiation.

  5. In-reactor oxidation of zircaloy-4 under low water vapor pressures

    SciTech Connect

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

    2015-01-01

    Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330 and 370 ºC). Data from these tests will be used to support the fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr- 4 over the specified range of test conditions. Comparisons between in- and ex-reactor test results were performed to evaluate the influence of irradiation.

  6. A Comparison of Photocatalytic Oxidation Reactor Performance for Spacecraft Cabin Trace Contaminant Control Applications

    NASA Technical Reports Server (NTRS)

    Perry, Jay L.; Frederick, Kenneth R.; Scott, Joseph P.; Reinermann, Dana N.

    2011-01-01

    Photocatalytic oxidation (PCO) is a maturing process technology that shows potential for spacecraft life support system application. Incorporating PCO into a spacecraft cabin atmosphere revitalization system requires an understanding of basic performance, particularly with regard to partial oxidation product production. Four PCO reactor design concepts have been evaluated for their effectiveness for mineralizing key trace volatile organic com-pounds (VOC) typically observed in crewed spacecraft cabin atmospheres. Mineralization efficiency and selectivity for partial oxidation products are compared for the reactor design concepts. The role of PCO in a spacecraft s life support system architecture is discussed.

  7. Real-Time Secondary Aerosol Formation Measurements using a Photooxidation Reactor (PAM) and AMS in Urban Air and Biomass Smoke

    NASA Astrophysics Data System (ADS)

    Ortega, A. M.; Cubison, M.; Hayes, P. L.; Brune, W. H.; Hu, W.; Flynn, J. H.; Grossberg, N.; Lefer, B. L.; Alvarez, S. L.; Rappenglueck, B.; Bon, D.; Graus, M.; Warneke, C.; Gilman, J. B.; Kuster, W. C.; De Gouw, J. A.; Sullivan, A. P.; Jimenez, J. L.

    2011-12-01

    Recent field studies reveal large formation of secondary organic aerosol (SOA) under urban polluted ambient conditions, while SOA formation in biomass burning smoke appears to be variable but sometimes substantial. To study this formation in real-time, a Potential Aerosol Mass (PAM) photooxidation reactor was deployed with submicron aerosol size and chemical composition measurements during two studies: FLAME-3, a biomass-burning study at USDA Fire Sciences Laboratory in Missoula in 2009, MT and CalNex-LA in Pasadena, CA in 2010. A high-resolution aerosol mass spectrometer (HR-AMS) and a scanning mobility particle sizer (SMPS) alternated sampling unprocessed and PAM-processed aerosol. The PAM reactor produces OH concentrations up to 4 orders of magnitude higher than in ambient air, achieving equivalent aging of ~2 weeks in 5 minutes of processing. The OH intensity was also scanned every 20 min. in both field studies. Results show the value of PAM-AMS as a tool for in-situ evaluation of changes in OA concentration and composition due to SOA formation and POA oxidation. In FLAME-3, net SOA formation was variable among smokes from different biomasses; however, OA oxidation was always observed. The average SOA enhancement factor was 1.7 +/- 0.5 of the initial POA. Reactive VOCs such as toluene, monoterpenes, and acetaldehyde, as measured from a PIT-MS, decreased with increased PAM processing; however, formic acid, acetone, and some unidentified OVOCs increased after significant exposure to high oxidant levels suggesting multigenerational chemistry. Results from CalNex-LA show enhancement of SOA and inorganic aerosol from gas-phase precursors. This enhanced OA mass increase from PAM processing is maximum at night and correlates with trimethylbenzene concentrations, which indicates the dominance of short-lived SOA precursors in the LA Basin. A traditional SOA model with mostly aromatic precursors underpredicts the amount of SOA formed by about an order-of-magnitude, which

  8. Energy-efficient wastewater treatment via the air-based, hybrid membrane biofilm reactor (hybrid MfBR).

    PubMed

    Aybar, M; Pizarro, G; Boltz, J P; Downing, L; Nerenberg, R

    2014-01-01

    We used modeling to predict the energy and cost savings associated with the air-based, hybrid membrane-biofilm reactor (hybrid MfBR). This process is obtained by replacing fine-bubble diffusers in conventional activated sludge with air-supplying, hollow-fiber membrane modules. Evaluated processes included removal of chemical oxygen demand (COD), combined COD and total nitrogen (TN) removal, and hybrid growth (biofilm and suspended). Target concentrations of COD and TN were based on high-stringency water reuse scenarios. Results showed reductions in power requirements as high as 86%. The decrease mainly resulted from the dramatically lower air flows for the MBfR, resulting from its higher oxygen-transfer efficiencies. When the MBfR was used for COD and TN removal, savings up to US$200/1,000 m(3) of treated water were predicted. Cost savings were highly sensitive to the costs of the membrane modules and electrical power. The costs were also very sensitive to membrane oxidation flux for ammonia, and the membrane life. These results suggest the hybrid MBfR may provide significant savings in energy and costs. Further research on the identified key parameters can help confirm these modeling predictions and facilitate scale-up. PMID:24759536

  9. Controlled CO preferential oxidation

    DOEpatents

    Meltser, Mark A.; Hoch, Martin M.

    1997-01-01

    Method for controlling the supply of air to a PROX reactor for the preferential oxidation in the presence of hydrogen wherein the concentration of the hydrogen entering and exiting the PROX reactor is monitored, the difference therebetween correlated to the amount of air needed to minimize such difference, and based thereon the air supply to the PROX reactor adjusted to provide such amount and minimize such difference.

  10. Wet air oxidation of solid waste made of polymers

    SciTech Connect

    Krisner, E.; Ambrosio, M.; Massiani, C.

    2000-03-01

    Wet air oxidation was attempted on synthetic (mixture of plastics of various compositions) and natural (cellulose substances) solid polymers. The temperature was maintained at 270 C and the oxygen pressure varied from 0 to 2 MPa (from understoichiometric conditions to oxygen excess). No valorizable compounds were found, even in runs carried out under an oxygen deficit. Suitable conditions for the total destruction of the initial polymers were temperatures above 270 C, an excess of oxygen, and a residence time of less than 1 h. Only such degradable compounds as acetic and benzoic acids are found at low concentrations. Formation of chlorine and gaseous hydrochloric acid can be limited by adding CaCO{sub 3} as a neutralizing agent.

  11. Destruction of hazardous air pollutants using a fast rise time pulsed corona reactor

    SciTech Connect

    Korzekwa, R.A.; Grothaus, M.G.; Hutcherson, R.K.; Roush, R.A.; Brown, R.

    1998-04-01

    Increasingly stringent environmental regulation imposed on both the military and civilian sectors has created a growing demand for alternative abatement methods for a variety of hazardous compounds. One alternative, the nonthermal plasma, shows promise of providing an efficient means for the destruction of dilute concentrations of hazardous air pollutants. The Dahlgren Laboratory of the Naval Surface Warfare Center has extensively investigated one type of nonthermal plasma discharge, the pulsed corona reactor, for the destruction of volatile organic compounds and chemical warfare agents. In this reactor, a fast rise time ({approximately}10ns), short duration ({lt}100ns), high-voltage pulse is repetitively delivered to a wire-cylinder electrode geometry, thereby producing a multitude of streamer discharges along its length. The resulting nonthermal plasma contains highly reactive chemical radicals which can interact with and destroy the hazardous molecules entrained in the ambient atmosphere flowing through the reactor volume. Increased electrical efficiency was obtained using a combination of high efficiency constant-current capacitor-charging, high repetition-rate spark gap switching, and resonant energy transfer to the reactor. Promising results have been obtained for toluene, methylene chloride, and dichlorodifluoromethane in air at concentrations of a few hundred parts per million. The device has been operated at voltages up to 30 kV, pulse repetition rates up to 1.4 kHz, and flow rates up to 60 scr(l)/min. Detailed electrical measurements have been made to properly characterize the electrical properties of the pulsed corona reactor and to validate subsequent improvements in the reactor energy efficiency. {copyright} {ital 1998 American Institute of Physics.}

  12. Research Reactor Preparations for the Air Shipment of Highly Enriched Uranium from Romania

    SciTech Connect

    K. J. Allen; I. Bolshinsky; L. L. Biro; M. E. Budu; N. V. Zamfir; M. Dragusin; C. Paunoiu; M. Ciocanescu

    2010-03-01

    In June 2009 two air shipments transported both unirradiated (fresh) and irradiated (spent) Russian-origin highly enriched uranium (HEU) nuclear fuel from two research reactors in Romania to the Russian Federation for conversion to low enriched uranium. The Institute for Nuclear Research at Pitesti (SCN Pitesti) shipped 30.1 kg of HEU fresh fuel pellets to Dimitrovgrad, Russia and the Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH) shipped 23.7 kilograms of HEU spent fuel assemblies from the VVR S research reactor at Magurele, Romania, to Chelyabinsk, Russia. Both HEU shipments were coordinated by the Russian Research Reactor Fuel Return Program (RRRFR) as part of the U.S. Department of Energy Global Threat Reduction Initiative (GTRI), were managed in Romania by the National Commission for Nuclear Activities Control (CNCAN), and were conducted in cooperation with the Russian Federation State Corporation Rosatom and the International Atomic Energy Agency. Both shipments were transported by truck to and from respective commercial airports in Romania and the Russian Federation and stored at secure nuclear facilities in Russia until the material is converted into low enriched uranium. These shipments resulted in Romania becoming the 3rd country under the RRRFR program and the 14th country under the GTRI program to remove all HEU. This paper describes the research reactor preparations and license approvals that were necessary to safely and securely complete these air shipments of nuclear fuel.

  13. Air contamination with nitric oxide: effect on exhaled nitric oxide response.

    PubMed

    Therminarias, A; Flore, P; Favre-Juvin, A; Oddou, M F; Delaire, M; Grimbert, F

    1998-03-01

    This study examines the response of exhaled nitric oxide (NO) concentration (ECNO) and quantity of exhaled NO over time (EVNO) in 10 healthy subjects breathing into five polyethylene bags, one in which synthetic air was free of NO and four in which NO was diluted to concentrations of 20 +/- 0.6, 49 +/- 0.8, 98 +/- 2, and 148 +/- 2 ppb, respectively. Each subject was connected to each bag for 10 min at random. Minute ventilation and ECNO were measured continuously, and EVNO was calculated continuously. ECNO and EVNO values were significantly higher for an inhaled NO concentration of 20 ppb than for NO-free air. Above 20 ppb, ECNO and EVNO increased linearly with inhaled NO concentration. It is reasonable to assume that a share of the quantity of inspired NO over time (InspVNO) because of air contamination by pollution is rejected by the ventilatory pathway. Insofar as InspVNO does not affect endogenous production or the metabolic fate of NO in the airway, this share may be estimated as being approximately one third of InspVNO, the remainder being taken by the endogenous pathway. Thus, air contamination by the NO resulting from pollution greatly increases the NO response in exhaled air. PMID:9517592

  14. Increased amount of nitric oxide in exhaled air of asthmatics.

    PubMed

    Alving, K; Weitzberg, E; Lundberg, J M

    1993-10-01

    The presence of nitric oxide (NO) in the exhaled air of humans has recently been described. We wanted to assess at what level exhaled NO originates in normal airways, and to determine whether airway inflammation induces changes in the levels of exhaled NO. Exhaled NO was continuously measured by chemiluminescence technique during normal tidal breathing through the nose or mouth, with a detection limit of 1 part per billion (ppb). Twelve control subjects were compared to eight patients with mild atopic asthma and rhinitis caused by occupational allergen. In control subjects, the major part of NO in exhaled air (up to 30 ppb) seemed to originate in the nasal airways, with only minor contribution from the lower airways and the oral cavity. However, in mild asthmatics, the level of exhaled NO during oral breathing, indicating the involvement of the lower airways, was increased 2-3 fold. Since increased production of NO in the lower airways may involve activated macrophages or neutrophils, we suggest that exhaled NO may be used to instantly monitor ongoing bronchial inflammation, at least when involving inducible NO synthase. PMID:7507065

  15. Treatment of hydraulic fracturing wastewater by wet air oxidation.

    PubMed

    Wang, Wei; Yan, Xiuyi; Zhou, Jinghui; Ma, Jiuli

    2016-01-01

    Wastewater produced by hydraulic fracturing for oil and gas production is characterized by high salinity and high chemical oxygen demand (COD). We applied a combination of flocculation and wet air oxidation technology to optimize the reduction of COD in the treatment of hydraulic fracturing wastewater. The experiments used different values of flocculant, coagulant, and oxidizing agent added to the wastewater, as well as different reaction times and treatment temperatures. The use of flocculants for the pretreatment of fracturing wastewater was shown to improve treatment efficiency. The addition of 500 mg/L of polyaluminum chloride (PAC) and 20 mg/L of anionic polyacrylamide (APAM) during pretreatment resulted in a COD removal ratio of 8.2% and reduced the suspended solid concentration of fracturing wastewater to 150 mg/L. For a solution of pretreated fracturing wastewater with 12 mL of added H2O2, the COD was reduced to 104 mg/L when reacted at 300 °C for 75 min, and reduced to 127 mg/L when reacted at the same temperature for 45 min while using a 1 L autoclave. An optimal combination of these parameters produced treated wastewater that met the GB 8978-1996 'Integrated Wastewater Discharge Standard' level I emission standard. PMID:26942530

  16. The burnup dependence of light water reactor spent fuel oxidation

    SciTech Connect

    Hanson, B.D.

    1998-07-01

    Over the temperature range of interest for dry storage or for placement of spent fuel in a permanent repository under the conditions now being considered, UO{sub 2} is thermodynamically unstable with respect to oxidation to higher oxides. The multiple valence states of uranium allow for the accommodation of interstitial oxygen atoms in the fuel matrix. A variety of stoichiometric and nonstoichiometric phases is therefore possible as the fuel oxidizers from UO{sub 2} to higher oxides. The oxidation of UO{sub 2} has been studied extensively for over 40 years. It has been shown that spent fuel and unirradiated UO{sub 2} oxidize via different mechanisms and at different rates. The oxidation of LWR spent fuel from UO{sub 2} to UO{sub 2.4} was studied previously and is reasonably well understood. The study presented here was initiated to determine the mechanism and rate of oxidation from UO{sub 2.4} to higher oxides. During the early stages of this work, a large variability in the oxidation behavior of samples oxidized under nearly identical conditions was found. Based on previous work on the effect of dopants on UO{sub 2} oxidation and this initial variability, it was hypothesized that the substitution of fission product and actinide impurities for uranium atoms in the spent fuel matrix was the cause of the variable oxidation behavior. Since the impurity concentration is roughly proportional to the burnup of a specimen, the oxidation behavior of spent fuel was expected to be a function of both temperature and burnup. This report (1) summarizes the previous oxidation work for both unirradiated UO{sub 2} and spent fuel (Section 2.2) and presents the theoretical basis for the burnup (i.e., impurity concentration) dependence of the rate of oxidation (Sections 2.3, 2.4, and 2.5), (2) describes the experimental approach (Section 3) and results (Section 4) for the current oxidation tests on spent fuel, and (3) establishes a simple model to determine the activation energies

  17. 76 FR 46083 - Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Sulfur

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-01

    ...This proposed rule is being issued as required by a consent decree governing the schedule for completion of this review of the air quality criteria and the secondary national ambient air quality standards (NAAQS) for oxides of nitrogen and oxides of sulfur. Based on its review, EPA proposes to retain the current nitrogen dioxide (NO2) and sulfur dioxide (SO2) secondary......

  18. Oxidation resistance of selected mechanical carbons at 650 deg C in dry flowing air

    NASA Technical Reports Server (NTRS)

    Allen, G. P.; Wisander, D. W.

    1973-01-01

    Oxidation experiments were conducted with several experimental mechanical carbons at 650 C in air flowing at 28 cu cm/sec (STP). Experiments indicate that boron carbide addition and zinc phosphate treatment definitely improved oxidation resistance. Impregnation with coal tar pitch before final graphitization had some beneficial effect on oxidation resistance and it markedly improved flexure strength and hardness. Graphitization temperature alone did not affect oxidation resistance, but with enough added boron carbide the oxidation resistance was increased although the hardness greatly decreased.

  19. 40 CFR 50.5 - National secondary ambient air quality standard for sulfur oxides (sulfur dioxide).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 2 2010-07-01 2010-07-01 false National secondary ambient air quality standard for sulfur oxides (sulfur dioxide). 50.5 Section 50.5 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS §...

  20. 78 FR 54813 - Approval and Promulgation of Air Quality Implementation Plans; Maine; Oxides of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-06

    ... AGENCY 40 CFR Parts 52 Approval and Promulgation of Air Quality Implementation Plans; Maine; Oxides of... comment period on our proposed Approval and Promulgation of Air Quality Implementation Plans; Maine... materials are available either electronically in www.regulations.gov or in hard copy at Air Quality...

  1. Catalytic air oxidation of biomass-derived carbohydrates to formic acid.

    PubMed

    Li, Jiang; Ding, Dao-Jun; Deng, Li; Guo, Qing-Xiang; Fu, Yao

    2012-07-01

    An efficient catalytic system for biomass oxidation to form formic acid was developed. The conversion of glucose to formic acid can reach up to 52% yield within 3 h when catalyzed by 5 mol% of H(5)PV(2)Mo(10)O(40) at only 373 K using air as the oxidant. Furthermore, the heteropolyacid can be used as a bifunctional catalyst in the conversion of cellulose to formic acid (yield=35%) with air as the oxidant. PMID:22499553

  2. Wet oxidation of an azo dye: Lumped kinetics in batch and mixed flow reactors

    SciTech Connect

    Donlagic, J.; Levec, J.

    1999-12-01

    Oxidation of a dilute aqueous solution of a model azo dye pollutant (Orange II) was studied in batch and continuous well-mixed (CSTR) reactors. Both reactors operate at 200--250 C, and total pressures up to 50 bar and at oxygen partial pressure from 10 to 30 bar. The model pollutant concentrations were in a range between 100 and 1,000 mg/L, which may be found in industrial wastewaters. The dye oxidation undergoes parallel-consecutive reaction pathways, in which it first decomposes thermally and oxidatively to aromatic intermediates and via organic acids to the final product carbon dioxide. To develop a kinetic equation capable of predicting organic carbon reduction, all organic species present in solution were lumped by total organic carbon (TOC). The lumped oxidation rate in batch reactor exhibited second-order behavior, whereas in the CSTR is was found linearly proportional to its TOC concentration. The lump behavior in batch reactor was dominated by the refractory low molecular mass aliphatic acids formed during the oxidation.

  3. Air feed tube support system for a solid oxide fuel cell generator

    DOEpatents

    Doshi, Vinod B.; Ruka, Roswell J.; Hager, Charles A.

    2002-01-01

    A solid oxide fuel cell generator (12), containing tubular fuel cells (36) with interior air electrodes (18), where a supporting member (82) containing a plurality of holes (26) supports oxidant feed tubes (51), which pass from an oxidant plenum (52") into the center of the fuel cells, through the holes (26) in the supporting member (82), where a compliant gasket (86) around the top of the oxidant feed tubes and on top (28) of the supporting member (82) helps support the oxidant feed tubes and center them within the fuel cells, and loosen the tolerance for centering the air feed tubes.

  4. A flow reactor study of the oxidation of n-octane and iso-octane

    SciTech Connect

    Dryer, F.L.; Brezinsky, K.

    1986-01-01

    An experimental study has been conducted in a flow reactor on the oxidation of n-octane and iso-octane at 1080 K, one atmosphere pressure and equivalence ratio equal to one. It was found that (despite similar ratios of initial fuel decay) the conversion of the reaction intermediates to CO and CO/sub 2/ is much slower during the oxidation of iso-octane than n-octane. Iso-octane produced primarily iso-butylene and propylene as intermediate hydrocarbons whereas n-octane oxidation resulted primarily in the formation of ethylene. Both the nature of the intermediates formed from each fuel and the relative rates of oxidation of the intermediates were shown to be related to the number of primary, secondary and tertiary H atoms present in the initial fuel. The basic chemistry revealed by the flow reactor experiments is suggestive of new insights into the chemical phenomena pertinent to knock in spark ignition engines.

  5. Thermal Catalytic Oxidation of Airborne Contaminants by a Reactor Using Ultra-Short Channel Length, Monolithic Catalyst Substrates

    NASA Technical Reports Server (NTRS)

    Perry, J. L.; Tomes, K. M.; Tatara, J. D.

    2005-01-01

    Contaminated air, whether in a crewed spacecraft cabin or terrestrial work and living spaces, is a pervasive problem affecting human health, performance, and well being. The need for highly effective, economical air quality processes spans a wide range of terrestrial and space flight applications. Typically, air quality control processes rely on absorption-based processes. Most industrial packed-bed adsorption processes use activated carbon. Once saturated, the carbon is either dumped or regenerated. In either case, the dumped carbon and concentrated waste streams constitute a hazardous waste that must be handled safely while minimizing environmental impact. Thermal catalytic oxidation processes designed to address waste handling issues are moving to the forefront of cleaner air quality control and process gas decontamination processes. Careful consideration in designing the catalyst substrate and reactor can lead to more complete contaminant destruction and poisoning resistance. Maintenance improvements leading to reduced waste handling and process downtime can also be realized. Performance of a prototype thermal catalytic reaction based on ultra-short waste channel, monolith catalyst substrate design, under a variety of process flow and contaminant loading conditions, is discussed.

  6. Controlling emissions from a black liquor fluidized bed evaporator (Copeland reactor) using a regenerative thermal oxidizer and a prefilter

    SciTech Connect

    Grzanka, R.

    1997-12-31

    This paper reports on an intriguing pilot project developed to control air emissions from a pulp mill. Testing is complete, and the results show favorable emissions reductions. Stone Container Corporation, REECO, NCASI, the Ohio DEP, and the US EPA, have all worked together and approved the installation of control equipment, for VOC and HAP emissions under Presumptive MACT, setting the standard for the Copeland Reactor process in a semi chem pulp mill. The equipment, once operational, will reduce VOC and CO emissions by greater than 90%. This installation will be done at one seventh the cost of the significant process modifications required to accomplish the same emission reduction. In addition, increased process operating efficiency will be achieved with the use of an energy recovery system. The process is a black liquor fluidized bed boiler, which is used to generate sodium carbonate from the black liquor. The vapor emissions were high in VOCs, CO and particulate. After much study and testing, a wet electrostatic precipitator was chosen as the filter system for particulate control, followed by a regenerative thermal oxidizer for VOC and HAP control, finally an air-to-air heat exchanger is being used to preheat the combustion air entering the process.

  7. An integrated approach for the verification of fresh mixed oxide fuel (MOX) assemblies at light water reactor MOX recycle reactors

    SciTech Connect

    Menlove, Howard O; Lee, Sang - Yoon

    2009-01-01

    This paper presents an integrated approach for the verification of mixed oxide (MOX) fuel assemblies prior to their being loaded into the reactor. There is a coupling of the verification approach that starts at the fuel fabrication plant and stops with the transfer of the assemblies into the thermal reactor. The key measurement points are at the output of the fuel fabrication plant, the receipt at the reactor site, and the storage in the water pool as fresh fuel. The IAEA currently has the capability to measure the MOX fuel assemblies at the output of the fuel fabrication plants using a passive neutron coincidence counting systems of the passive neutron collar (PNCL) type. Also. at the MOX reactor pool, the underwater coincidence counter (UWCC) has been developed to measure the MOX assemblies in the water. The UWCC measurement requires that the fuel assembly be lifted about two meters up in the storage rack to avoid interference from the fuel that is stored in the rack. This paper presents a new method to verify the MOX fuel assemblies that are in the storage rack without the necessity of moving the fuel. The detector system is called the Underwater MOX Verification System (UMVS). The integration and relationship of the three measurements systems is described.

  8. Oxidative cyclization of alkenols with Oxone using a miniflow reactor

    PubMed Central

    Yamada, Yoichi M A; Torii, Kaoru

    2009-01-01

    Summary A miniflow system for oxidative cyclization of alkenols with Oxone was developed. Thus, the oxidative cyclization of (Z)- and (E)-alkenols in i-PrOH with an aqueous solution of Oxone proceeded smoothly and safely in a PTFE tube without any exogenous catalytic species, and was subsequently quenched in a flow-reaction manner to afford the corresponding furanyl and pyranyl carbinols quantitatively within 5 or 10 min of residence time. PMID:19513188

  9. Calculated power distribution of a thermionic, beryllium oxide reflected, fast-spectrum reactor

    NASA Technical Reports Server (NTRS)

    Mayo, W.; Lantz, E.

    1973-01-01

    A procedure is developed and used to calculate the detailed power distribution in the fuel elements next to a beryllium oxide reflector of a fast-spectrum, thermionic reactor. The results of the calculations show that, although the average power density in these outer fuel elements is not far from the core average, the power density at the very edge of the fuel closest to the beryllium oxide is about 1.8 times the core avearge.

  10. Environmentally friendly efficient coupling of n-heptane by sulfated tri-component metal oxides in slurry bubble column reactor.

    PubMed

    Ma, Hongzhu; Xiao, Jing; Wang, Bo

    2009-07-30

    SO(4)(2-)/M(x)O(y) is of the greatest interest in solid catalysts and green catalysts. Slurry bubble column reactors are of considerable interest in industrial processes and various biochemical processes. The cetane number (CN) has widely used diesel fuel quality parameter related to the ignition delay time (and combustion quality) of a fuel. CN improvement of diesel fuels is a difficult task that refiners will face in the near future. For that purpose, the tests were designed in which n-heptane is used as the reactant in the air or ozone atmosphere at room temperature (RT) and local atmospheric pressure (LAP) using different catalysts of sulfated tri-component metal oxides SO(4)(2-)/Fe(2)O(3)-TiO2-SnO(2) (SFTSn) and SO(4)(2-)/MnO(2)-TiO2-SnO(2) (SMTSn) in slurry bubble column reactor. The products distribution was analyzed by gas chromatography-mass spectrometry (GC-MS) method and the results show that the relative selectivity of long linear alkane (C(12)-C(28)) reaches the maximum (87.330%) when SMTSn is used as catalyst in flow air at 60 min. Diesel fuel components with higher cetane numbers can be easily obtained from this study. PMID:19124196

  11. Laboratory flammability studies of mixtures of hydrogen, nitrous oxide, and air

    SciTech Connect

    Cashdollar, K L; Hertzberg, M; Zlochower, I A; Lucci, C E; Green, G M; Thomas, R A

    1992-06-26

    At the request of the Department of Energy and the Westinghouse Hanford Company, the Bureau of Mines has investigated the flammability of mixtures of hydrogen, nitrous oxide, and air. This work is relevant to the possible hazards of flammable gas generation from nuclear waste tanks at Hanford, WA. The tests were performed in a 120-L spherical chamber under both quiescent and turbulent conditions using both electric spark and pyrotechnic ignition sources. The data reported here for binary mixtures of hydrogen in air generally confirm the data of previous investigators, but they are more comprehensive than those reported previously. The results clarify to a greater extent the complications associated with buoyancy, turbulence, and selective diffusion. The data reported here for ternary mixtures of hydrogen and nitrous oxide in air indicate that small additions of nitrous oxide (relative to the amount of air) have little effect, but that higher concentrations of nitrous oxide (relative to air) significantly increase the explosion hazard.

  12. Cultivation of nitrite-dependent anaerobic methane-oxidizing bacteria: impact of reactor configuration.

    PubMed

    Hu, Baolan; He, Zhanfei; Geng, Sha; Cai, Chen; Lou, Liping; Zheng, Ping; Xu, Xinhua

    2014-09-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) is mediated by bacteria that anaerobically oxidize methane coupled with nitrite reduction and is a potential bioprocess for wastewater treatment. In this work, the effect of reactor configuration on n-damo bacterial cultivation was investigated. A magnetically stirred gas lift reactor (MSGLR), a sequencing batch reactor (SBR), and a continuously stirred tank reactor (CSTR) were selected to cultivate the bacteria. Microbial community was monitored by using quantitative PCR, 16S rRNA gene sequencing, pmoA gene sequencing, and fluorescence in situ hybridization (FISH). The effects of substrate inhibition, methane mass transfer, and biomass washout in the three reactors were focused on. The results indicated that the MSGLR had the best performance among the three reactor systems, with the highest total and specific n-damo activities. Its maximum volumetric nitrogen removal rate was up to 76.9 mg N L(-1) day(-1), which was higher than previously reported values (5.1-37.8 mg N L(-1) d(-1)). PMID:24880628

  13. Air-lift internal loop biofilm reactor for realized simultaneous nitrification and denitrification.

    PubMed

    Zhang, Cuiyi; Wang, Lu; Yan, Ning; Zhang, Yongming; Liu, Rui

    2013-05-01

    Simultaneous nitrification and denitrification (SND) was realized by means of a novel air-lift internal loop biofilm reactor, in which aeration was set in middle of the reactor. During operation, the aeration was adjusted to get appropriate dissolve oxygen (DO) in bulk solution and let aerobic and anoxic zone coexist in one reactor. When aeration was at 0.6 and 0.2 L/min, corresponding to DO of 5.8 and 2.5 mg/L in bulk solution, ammonia nitrogen removal percentage reached about 80 and 90 %, but total nitrogen removal percentage was lower than 25 %. While the aeration was reduced to 0.1 L/min, aerobic and anoxic zones existed simultaneously in one reactor to get 75 % of ammonia nitrogen and 50 % of total nitrogen removal percentage. Biofilms were, respectively, taken from aerobic and anoxic zone to verify their function of nitrification and denitrification in two flasks, in which ammonia nitrogen was transferred into nitrate completely by aerobic biofilm, and nitrate was removed more than 80 % by anoxic biofilm. Microelectrode was used to measure the DO distribution inside biofilms in anoxic zone corresponding to different aerations. When aeration was at 0.6 and 0.2 L/min, DO inside biofilm was more than 1.5 mg/L, but the DO inside biofilm decreased to anoxic status with depth of biofilm increasing corresponding to aeration of 0.1 L/min. The experimental results indicated that SND could be realized because of simultaneous existence of aerobic and anoxic biofilms in one reactor. PMID:23001679

  14. TRICHLOROETHYLENE SORPTION AND OXIDATION USING A DUAL FUNCTION SORBENT/CATALYST IN A FALLING FURNACE REACTOR

    EPA Science Inventory

    A dual function medium (Cr-ZSM-5), capable of physisorbing trichloroethylene (TCE) at ambient temperature and catalytically oxidizing it at elevated temperature (-350 degrees C) was utilized in a novel continuous falling furnace reactor system to store and periodically destroy t...

  15. Effects of substrates on N2O emissions in an anaerobic ammonium oxidation (anammox) reactor.

    PubMed

    Jin, Yue; Wang, Dunqiu; Zhang, Wenjie

    2016-01-01

    N2O emission in the anaerobic ammonium oxidation (anammox) process is of growing concern. In this study, effects of substrate concentrations on N2O emissions were investigated in an anammox reactor. Extremely high N2O emissions of 1.67 % were led by high NH4-N concentrations. Results showed that N2O emissions have a positive correlation with NH4-N concentrations in the anammox reactor. Reducing NH4-N concentrations by recycling pump resulted in decreasing N2O emissions. In addition, further studies were performed to identify a key biological process that is contributed to N2O emissions from the anammox reactor. Based on the results obtained, Nitrosomonas, which can oxidize ammonia to nitrite, was deemed as the main sources of N2O emissions. PMID:27376009

  16. Planar ceramic membrane assembly and oxidation reactor system

    DOEpatents

    Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohrn, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, Paul Nigel

    2009-04-07

    Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

  17. Planar ceramic membrane assembly and oxidation reactor system

    DOEpatents

    Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohm, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, deceased, Paul Nigel

    2007-10-09

    Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

  18. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2...

  19. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2...

  20. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2...

  1. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2...

  2. Leaf photosynthetic and water-relations responses for 'Valencia' orange trees exposed to oxidant air pollution

    SciTech Connect

    Olszyk, D.M.; Takemoto, B.K.; Poe, M.

    1991-01-01

    Leaf responses were measured to test a hypothesis that reduced photosynthetic capacity and/or altered water relations were associated with reductions in yield for 'Valencia' orange trees (Citrus sinensis (L.), Osbeck) exposed to ambient oxidant air pollution. Exposures were continuous for 4 years to three levels of oxidants (in charcoal-filtered, half-filtered, and non-filtered air). Oxidants had no effect on net leaf photosynthetic rates or on photosynthetic pigment concentrations. A single set of measurements indicated that oxidants increased leaf starch concentrations (24%) prior to flowering, suggesting a change in photosynthate allocation. Leaves exposed to oxidants had small, but consistent, changes in water relations over the summer growing season, compared to trees growing in filtered air. Other changes included decreased stomatal conductance (12%) and transpiration (9%) rates, and increased water pressure potentials (5%). While all responses were subtle, their cumulative impact over 4 years indicated that 'Valencia' orange trees were subject to increased ambient oxidant stress.

  3. Nitrogen removal from wastewater using simultaneous nitrate reduction and anaerobic ammonium oxidation in single reactor.

    PubMed

    Sumino, Tatsuo; Isaka, Kazuichi; Ikuta, Hajime; Saiki, Yuko; Yokota, Toyokazu

    2006-10-01

    The effects of C/N ratio and total organic carbon (TOC) loading on nitrogen removal through simultaneous nitrate reduction and anaerobic ammonium oxidation in a single reactor were examined. Granular sludge taken from a methane fermentation reactor was placed in an upflow reactor and supplied with synthetic wastewater containing nitrate at a C/N ratio of 1 to grow heterotrophic denitrifying bacteria. When nitrogen removal ratio reached 30%, anammox sludge attached to nonwoven-carrier was added into the same reactor and then ammonia was added to the synthetic wastewater. Nitrogen removal ratio was markedly increased to 80-94%. In this system, nitrogen removal ratio was affected by C/N ratio and TOC loading, not by the amount of granular sludge. A stable isotopic analysis using 15N-labeled nitrate showed that N2 gas was formed by anammox reaction. PMID:17116583

  4. Improving Corrosion Behavior in SCWR, LFR and VHTR Reactor Materials by Formation of a Stable Oxide

    SciTech Connect

    Arthur T. Motta; Robert Comstock; Ning Li; Todd Allen; Gary Was

    2009-12-21

    The objective of this study is to understand the influence of the alloy microstructure and composition on the formation of a stable, protective oxide in the environments relevant to the SCWR and LFR reactor concepts, as well as to the VHTR. It is proposed to use state-of-the art techniques to study the fine structure of these oxides to identify the structural differences between stable and unstable oxide layers. The techniques to be used are microbeam synchrotron radiation diffraction and fluorescence, and cross-sectional transmission electron microcopy on samples prepared using focused ion beam.

  5. Irradiation effects in oxide dispersion strengthened (ODS) Ni-base alloys for Gen. IV nuclear reactors

    NASA Astrophysics Data System (ADS)

    Oono, Naoko; Ukai, Shigeharu; Kondo, Sosuke; Hashitomi, Okinobu; Kimura, Akihiko

    2015-10-01

    Oxide particle dispersion strengthened (ODS) Ni-base alloys are irradiated by using simulation technique (Fe/He dual-ion irradiation) to investigate the reliability to Gen. IV high-temperature reactors. The fine oxide particles with less than 10 nm in average size and approximately 8.0 × 1022 m-3 in number density remained after 101 dpa irradiation. The tiny helium bubbles were inside grains, not at grain-boundaries; it is advantageous effect of oxide particles which trap the helium atoms at the particle-matrix interface. Ni-base ODS alloys demonstrated their great ability to overcome He embrittlement.

  6. Pressurized solid oxide fuel cell integral air accumular containment

    DOEpatents

    Gillett, James E.; Zafred, Paolo R.; Basel, Richard A.

    2004-02-10

    A fuel cell generator apparatus contains at least one fuel cell subassembly module in a module housing, where the housing is surrounded by a pressure vessel such that there is an air accumulator space, where the apparatus is associated with an air compressor of a turbine/generator/air compressor system, where pressurized air from the compressor passes into the space and occupies the space and then flows to the fuel cells in the subassembly module, where the air accumulation space provides an accumulator to control any unreacted fuel gas that might flow from the module.

  7. [Study on the start-up of anaerobic ammonium oxidation process in biological activated carbon reactor].

    PubMed

    Lai, Wei-Yi; Zhou, Wei-Li; He, Sheng-Bing

    2013-08-01

    In order to shorten the start-up time of anaerobic ammonium oxidation (ANAMMOX) reactor, biological activated cabon reactor was applied. Three lab scale UASB reactors were seeded with anaerobic sludge, fed with synthetic wastewater containing ammonia and nitrite, and supplemented with granular activated carbon on day 0, 33 and 56, respectively. The nitrogen removal performance of the first reactor, into which GAC was added on day 0, showed no significant improvement in 90 days. After being suspended for about one month, the secondary start-up of this reactor succeeded in another 33 days (totally 123 days). 49 d and 85 d were taken for the other two reactors started up by the addition of GAC on day 33 and 56, respectively. After the reactors were started up, the average removal rates of total nitrogen were 89.8%, 86.7% and 86.7%, respectively. The start-up process could be divided into four stages, namely, the bacterial autolysis phase, the lag phase, the improve phase and the stationary phase, and the best time for adding GAC carrier was right after the start of the lag phase. PMID:24191565

  8. Review of research results for the photocatalytic oxidation of hazardous wastes in air

    SciTech Connect

    Nimlos, M R; Wolfrum, E J; Gratson, D A; Watt, A S; Jacoby, W A; Turchi, C

    1995-01-01

    Laboratory experiments of gas-phase photocatalytic oxidation (PCO) at NREL have focused on measurements that can help commercialize this technology for treating gaseous air streams. This effort proceeds earlier NREL work and studies conducted elsewhere which demonstrated the general applicability of PCO. The more recent work has concentrated on: (1) the kinetics of the PCO process; (2) the formation and destruction of intermediates; and (3) possible enhancements to improve the destruction rates. The results from these studies will be used to help design large scale PCO equipment and they will be used to evaluate the economics of the PCO process. For trichloroethylene and ethanol, extensive studies of the rates of destruction have yielded kinetic parameters for the destruction of intermediates as well as the substrate. The kinetics of intermediates is essential for sizing a large scale reactor, as complete conversion to carbon dioxide is often desired. The kinetic data from these laboratory studies has been used for analyzing IT`s pilot PCO reactor and has been used to suggest modifications to this unit. For compounds that are more difficult to destroy (such as the components of BTEX), rate enhancement experiments have been conducted. These compounds represent a very large market for this technology and improvement of the rate of the process should make it competitive. Towards this goal, the enhancement of the destruction of BTEX components have been studied. Experiments have demonstrated that there is a significant increase in the rates of destruction of BTEX with the addition of ozone. Preliminary economic assessments have shown that PCO with ozone may be cost competitive. Future laboratory experiments of PCO will focus on refinements of what has been learned. Rate measurements will also be expanded to include other compounds representing significant markets for the PCO technology.

  9. Experimental Study on Ash-Returned Reactor of CFB Atmospheric Air Gasifier

    NASA Astrophysics Data System (ADS)

    Shihong, Zhang; Luning, Tian; Xianrong, Zhou; Hanping, Chen; Haiping, Yang; Xianhua, Wang

    In an attempt to improve the gasification efficiency and decrease the carbon content in fly ash of atmospheric air CFB gasifiers, an innovatory equipment by name ash-returned reactor is put forward by SKLCC. Ash-returned reactor is an ash-returned apparatus on line of ash circulation, typically like "U" type valve in CFB boilers, with additional function of some extent combustion of residual carbon and increase the furnace inlet temperature of returning ash, and hence the coal conversion of gasifiers is enhanced. As to its configuration compared to conventional "U" type valve, ash-returned rector has two distinguished features of several times of height scale of fluidizing transportation region to meet the combustion reaction time need and appropriate heat transfer tube bundles arranged in the region to moderate the local temperature so as to avoid slagging. And hence, corresponding to the structure renovation, the material transportation and regulation performance of ash-returned reactor is primarily investigated through a series of experiments in a cold lab-scale facility in this paper. The heat transfer characteristic of the tube bundles is then researched and its influential factors are further discussed. These works lay a foundation on the following study of hot state experiments and industrial applications.

  10. Protected air-cooled condenser for the Clinch River Breeder Reactor Plant

    SciTech Connect

    Louison, R.; Boardman, C.E.

    1981-05-29

    The long term residual heat removal for the Clinch River Breeder Reactor Plant (CRBRP) is accomplished through the use of three protected air-cooled condensers (PACC's) each rated at 15M/sub t/ following a normal or emergency shutdown of the reactor. Steam is condensed by forcing air over the finned and coiled condenser tubes located above the steam drums. The steam flow is by natural convection. It is drawn to the PACC tube bundle for the steam drum by the lower pressure region in the tube bundle created from the condensing action. The concept of the tube bundle employs a unique patented configuration which has been commercially available through CONSECO Inc. of Medfore, Wisconsin. The concept provides semi-parallel flow that minimizes subcooling and reduces steam/condensate flow instabilities that have been observed on other similar heat transfer equipment such as moisture separator reheaters (MSRS). The improved flow stability will reduce temperature cycling and associated mechanical fatigue. The PACC is being designed to operate during and following the design basis earthquake, depressurization from the design basis tornado and is housed in protective building enclosure which is also designed to withstand the above mentioned events.

  11. An evaluation of the performance and optimization of a new wastewater treatment technology: the air suction flow-biofilm reactor.

    PubMed

    Forde, P; Kennelly, C; Gerrity, S; Collins, G; Clifford, Eoghan

    2015-01-01

    In this laboratory study, a novel wastewater treatment technology, the air suction flow-biofilm reactor (ASF-BR) - a sequencing batch biofilm reactor technology with a passive aeration mechanism - was investigated for its efficiency in removing organic carbon, nitrogen and phosphorus, from high-strength synthetic wastewaters. A laboratory-scale ASF-BR comprising 2 reactors, 350 mm in diameter and 450 mm in height, was investigated over 2 studies (Studies 1 and 2) for a total of 430 days. Study 1 lasted a total of 166 days and involved a 9-step sequence alternating between aeration, anoxic treatment and settlement. The cycle time was 12.1 h and the reactors were operated at a substrate loading rate of 3.60 g filtered chemical oxygen demand (CODf)/m2 media/d, 0.28 g filtered total nitrogen (TNf)/m2 media/d, 0.24 g ammonium-nitrogen (NH4-N)/m2 media/d and 0.07 g ortho-phosphate (PO4-P)/m2 media/d. The average removal rates achieved during Study 1 were 98% CODf, 88% TNf, 97% NH4-N and 35% PO4-P. During Study 2 (264 days), the unit was operated at a loading rate of 2.49 g CODf/m2 media/d, 0.24 g TNf/m2 media/d, 0.20 g NH4-N/m2 media/d and 0.06 PO4-P/m2 media/d. The energy requirement during this study was reduced by modifying the treatment cycle in include fewer pumping cycles. Removal rates in Study 2 averaged 97% CODf, 86% TNf, 99% NH4-N and 76% PO4-P. The excess sludge production of the system was evaluated and detailed analyses of the treatment cycles were carried out. Biomass yields were estimated at 0.09 g SS/g CODf, removed and 0.21 g SS/g CODf, removed for Studies 1 and 2, respectively. Gene analysis showed that the use of a partial vacuum did not affect the growth of ammonia-oxidizing bacteria. The results indicate that the ASF-BR and passive aeration technologies can offer efficient alternatives to existing technologies. PMID:25413003

  12. Effect of inlet temperature on the performance of a catalytic reactor. [air pollution control

    NASA Technical Reports Server (NTRS)

    Anderson, D. N.

    1978-01-01

    A 12 cm diameter by 15 cm long catalytic reactor was tested with No. 2 diesel fuel in a combustion test rig at inlet temperatures of 700, 800, 900, and 1000 K. Other test conditions included pressures of 3 and 6 x 10 to the 5th power Pa, reference velocities of 10, 15, and 20 m/s, and adiabatic combustion temperatures in the range 1100 to 1400 K. The combustion efficiency was calculated from measurements of carbon monoxide and unburned hydrocarbon emissions. Nitrogen oxide emissions and reactor pressure drop were also measured. At a reference velocity of 10 m/s, the CO and unburned hydrocarbons emissions, and, therefore, the combustion efficiency, were independent of inlet temperature. At an inlet temperature of 1000 K, they were independent of reference velocity. Nitrogen oxides emissions resulted from conversion of the small amount (135 ppm) of fuel-bound nitrogen in the fuel. Up to 90 percent conversion was observed with no apparent effect of any of the test variables. For typical gas turbine operating conditions, all three pollutants were below levels which would permit the most stringent proposed automotive emissions standards to be met.

  13. A preliminary assessment of beryllium dust oxidation during a wet bypass accident in a fusion reactor

    SciTech Connect

    Brad J. Merrill; Richard L. Moore; J. Phillip Sharp

    2008-09-01

    A beryllium dust oxidation model has been developed at the Idaho National Laboratory (INL) by the Fusion Safety Program (FSP) for the MELCOR safety computer code. The purpose of this model is to investigate hydrogen production from beryllium dust layers on hot surfaces inside a fusion reactor vacuum vessel (VV) during in-vessel loss-of-cooling accidents (LOCAs). This beryllium dust oxidation model accounts for the diffusion of steam into a beryllium dust layer, the oxidation of the dust particles inside this layer based on the beryllium-steam oxidation equations developed at the INL, and the effective thermal conductivity of this beryllium dust layer. This paper details this oxidation model and presents the results of the application of this model to a wet bypass accident scenario in the ITER device.

  14. PHOTOCHEMICAL OXIDANT AIR POLLUTION EFFECTS ON A MIXED CONIFER FOREST FOREST ECOSYSTEM - A PROGRESS REPORT

    EPA Science Inventory

    Since 1972, twelve scientists representing several research disciplines have collaborated in integrated studies to determine the chronic effects of photochemical oxidant air pollutants on a western mixed conifer forest ecosystem. An enormous amount of data has been collected, des...

  15. The effect of clay particles on the activity of suspended autotrophic nitrifying bacteria and on the performance of an air-lift reactor.

    PubMed

    Vieira, M J; Pacheco, A P; Pinho, I A; Melo, L F

    2001-02-01

    Clay minerals have some properties, namely a high surface area and the ability of ion exchange that may exert some effects on microbial systems. It is often difficult to know the way the clay is exerting its influence and whether its presence improves a given metabolic process. The present work concerns the study of the effect of the addition of powdered kaolin to autotrophic nitrification systems, and includes the study of the effects of the particles on the activity of a suspended nitrifying bacteria consortium and on the performance of an air-lift biofilm reactor used for tertiary nitrification. Concerning the suspended culture, kaolin particles produced stimulation on the specific endogenous and exogenous respiration rates of the bacteria, probably due to a nutritional effect supplied by the clay. This effect was more pronounced for the ammonia oxidation rates, although nitrite oxidation was also enhanced but to a lesser extent. In respect to the presence of kaolin particles in the air-lift reactor, the results obtained indicate that the clay particles become incorporated in the biofilm pellets, but do not change significantly their thickness or their shape. However, nitrate production decreased when the concentration of particles increased. The low adsorption of ammonia by the kaolin indicated that the clay particles embedded in the biofilm did not probably retain the ions. Although it was not proved, precipitation of salts may have occurred. PMID:11349371

  16. Oxidation behavior of ammonium in a 3-dimensional biofilm-electrode reactor.

    PubMed

    Tang, Jinjing; Guo, Jinsong; Fang, Fang; Chen, Youpeng; Lei, Lijing; Yang, Lin

    2013-12-01

    Excess nitrogenous compounds are detrimental to natural water systems and to human health. To completely realize autohydrogenotrophic nitrogen removal, a novel 3-dimensional biofilm-electrode reactor was designed. Titanium was electroplated with ruthenium and used as the anode. Activated carbon fiber felt was used as the cathode. The reactor was separated into two chambers by a permeable membrane. The cathode chamber was filled with granular graphite and glass beads. The cathode and cathode chamber were inhabited with domesticated biofilm. In the absence of organic substances, a nitrogen removal efficiency of up to 91% was achieved at DO levels of 3.42 +/- 0.37 mg/L when the applied current density was only 0.02 mA/cm2. The oxidation of ammonium in biofilm-electrode reactors was also investigated. It was found that ammonium could be oxidized not only on the anode but also on particle electrodes in the cathode chamber of the biofilm-electrode reactor. Oxidation rates of ammonium and nitrogen removal efficiency were found to be affected by the electric current loading on the biofilm-electrode reactor. The kinetic model of ammonium at different electric currents was analyzed by a first-order reaction kinetics equation. The regression analysis implied that when the current density was less than 0.02 mA/cm2, ammonium removal was positively correlated to the current density. However, when the current density was more than 0.02 mA/cm2, the electric current became a limiting factor for the oxidation rate of ammonium and nitrogen removal efficiency. PMID:24649670

  17. Reaction rate constant for dry air oxidation of K Basin fuel

    SciTech Connect

    Trimble, D.J.

    1998-04-29

    The rate of oxidation of spent nuclear fuel stored in the K Basin water is an important parameter when assessing the processes and accident scenarios for preparing the fuel for dry storage. The literature provides data and rate laws for the oxidation of unirradiated uranium in various environments. Measurement data for the dry air oxidation of K Basin fuel is compared to the literature data for linear oxidation in dry air. Equations for the correlations and statistical bounds to the K Basin fuel data and the literature data are selected for predicting nominal and bounding rates for the dry air oxidation of the K Basin fuel. These rate equations are intended for use in the Spent Nuclear Fuel Project Technical Data book.

  18. Bioaugmentation of Syntrophic Acetate-Oxidizing Culture in Biogas Reactors Exposed to Increasing Levels of Ammonia

    PubMed Central

    Westerholm, Maria; Levén, Lotta

    2012-01-01

    The importance of syntrophic acetate oxidation for process stability in methanogenic systems operating at high ammonia concentrations has previously been emphasized. In this study we investigated bioaugmentation of syntrophic acetate-oxidizing (SAO) cultures as a possible method for decreasing the adaptation period of biogas reactors operating at gradually increased ammonia concentrations (1.5 to 11 g NH4+-N/liter). Whole stillage and cattle manure were codigested semicontinuously for about 460 days in four mesophilic anaerobic laboratory-scale reactors, and a fixed volume of SAO culture was added daily to two of the reactors. Reactor performance was evaluated in terms of biogas productivity, methane content, pH, alkalinity, and volatile fatty acid (VFA) content. The decomposition pathway of acetate was analyzed by isotopic tracer experiments, and population dynamics were monitored by quantitative PCR analyses. A shift in dominance from aceticlastic methanogenesis to SAO occurred simultaneously in all reactors, indicating no influence by bioaugmentation on the prevailing pathway. Higher abundances of Clostridium ultunense and Tepidanaerobacter acetatoxydans were associated with bioaugmentation, but no influence on Syntrophaceticus schinkii or the methanogenic population was distinguished. Overloading or accumulation of VFA did not cause notable dynamic effects on the population. Instead, the ammonia concentration had a substantial impact on the abundance level of the microorganisms surveyed. The addition of SAO culture did not affect process performance or stability against ammonia inhibition, and all four reactors deteriorated at high ammonia concentrations. Consequently, these findings further demonstrate the strong influence of ammonia on the methane-producing consortia and on the representative methanization pathway in mesophilic biogas reactors. PMID:22923397

  19. Material unaccounted for at the Southwest Experimental Fast Oxide Reactor: The SEFOR MUF

    SciTech Connect

    Higinbotham, W.A.

    1994-11-07

    The U.S. Atomic Energy Commission contracted with the General Electric Company to design, construct, and operate the Southwest Experimental Fast Oxide Reactor (SEFOR) to measure the Doppler effect for fast neutron breeder reactors. It contracted with Nuclear Fuel Services to fabricate the fuel rods for the reactor. When the reactor went critical in May, 1969, it appeared that some of the mixed uranium-plutonium oxide (MOX) fuel rods did not contain the specified quantity of plutonium. The SEFOR operators soon found several fuel rods which appeared to be low in plutonium. The safeguards group at Brookhaven was asked to look into the problem and, if possible, determine how much plutonium was missing from the unirradiated rods and from the larger number which had been slightly irradiated in the reactor. It was decided that the plutonium content of the unirradiated and irradiated rods could be measured relative to a reference rod using a high resolution gamma-ray detector and also by neutron measurements using an auto-correlation circuit recently developed at the Naval Research Laboratory (NRL). During the next two years, Brookhaven personnel and C.V. Strain of NRL made several trips to the SEFOR reactor. About 250 of the 775 rods were measured by two or more methods, using a sodium-iodide detector, a high-resolution germanium detector, a neutron detector, or the reactor (to measure reactivity). The research team concluded that 4.6 {+-} 0.46 kg of plutonium was missing out of the 433 kg that the rods should have contained. This report describes the SEFOR experiment and the procedures used to determine the material unaccounted for, or MUF.

  20. Warm Water Oxidation Verification - Scoping and Stirred Reactor Tests

    SciTech Connect

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

    2011-06-15

    Scoping tests to evaluate the effects of agitation and pH adjustment on simulant sludge agglomeration and uranium metal oxidation at {approx}95 C were performed under Test Instructions(a,b) and as per sections 5.1 and 5.2 of this Test Plan prepared by AREVA. (c) The thermal testing occurred during the week of October 4-9, 2010. The results are reported here. For this testing, two uranium-containing simulant sludge types were evaluated: (1) a full uranium-containing K West (KW) container sludge simulant consisting of nine predominant sludge components; (2) a 50:50 uranium-mole basis mixture of uraninite [U(IV)] and metaschoepite [U(VI)]. This scoping study was conducted in support of the Sludge Treatment Project (STP) Phase 2 technology evaluation for the treatment and packaging of K-Basin sludge. The STP is managed by CH2M Hill Plateau Remediation Company (CHPRC) for the U.S. Department of Energy. Warm water ({approx}95 C) oxidation of sludge, followed by immobilization, has been proposed by AREVA and is one of the alternative flowsheets being considered to convert uranium metal to UO{sub 2} and eliminate H{sub 2} generation during final sludge disposition. Preliminary assessments of warm water oxidation have been conducted, and several issues have been identified that can best be evaluated through laboratory testing. The scoping evaluation documented here was specifically focused on the issue of the potential formation of high strength sludge agglomerates at the proposed 95 C process operating temperature. Prior hydrothermal tests conducted at 185 C produced significant physiochemical changes to genuine sludge, including the formation of monolithic concretions/agglomerates that exhibited shear strengths in excess of 100 kPa (Delegard et al. 2007).

  1. Constraining Predicted Secondary Organic Aerosol Formation and Processing Using Real-Time Observations of Aging Urban Emissions in an Oxidation Flow Reactor

    NASA Astrophysics Data System (ADS)

    Ortega, A. M.; Palm, B. B.; Hayes, P. L.; Day, D. A.; Cubison, M.; Brune, W. H.; Hu, W.; Graus, M.; Warneke, C.; Gilman, J.; De Gouw, J. A.; Jimenez, J. L.

    2014-12-01

    To investigate atmospheric processing of urban emissions, we deployed an oxidation flow reactor with measurements of size-resolved chemical composition of submicron aerosol during CalNex-LA, a field study investigating air quality and climate change at a receptor site in the Los Angeles Basin. The reactor produces OH concentrations up to 4 orders of magnitude higher than in ambient air, achieving equivalent atmospheric aging of hours to ~2 weeks in 5 minutes of processing. The OH exposure (OHexp) was stepped every 20 min to survey the effects of a range of oxidation exposures on gases and aerosols. This approach is a valuable tool for in-situ evaluation of changes in organic aerosol (OA) concentration and composition due to photochemical processing over a range of ambient atmospheric conditions and composition. Combined with collocated gas-phase measurements of volatile organic compounds, this novel approach enables the comparison of measured SOA to predicted SOA formation from a prescribed set of precursors. Results from CalNex-LA show enhancements of OA and inorganic aerosol from gas-phase precursors. The OA mass enhancement from aging was highest at night and correlated with trimethylbenzene, indicating the importance of relatively short-lived VOC (OH lifetime of ~12 hrs or less) as SOA precursors in the LA Basin. Maximum net SOA production is observed between 3-6 days of aging and decreases at higher exposures. Aging in the reactor shows similar behavior to atmospheric processing; the elemental composition of ambient and reactor measurements follow similar slopes when plotted in a Van Krevelen diagram. Additionally, for air processed in the reactor, oxygen-to-carbon ratios (O/C) of aerosol extended over a larger range compared to ambient aerosol observed in the LA Basin. While reactor aging always increases O/C, often beyond maximum observed ambient levels, a transition from net OA production to destruction occurs at intermediate OHexp, suggesting a transition

  2. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor

    SciTech Connect

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-01

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  3. Comparison of dissolved-organic-carbon residuals from air- and pure-oxygen-activated-sludge sequencing-batch reactors.

    PubMed

    Esparza-Soto, Mario; Fox, Peter; Westerhoff, Paul

    2006-03-01

    Literature shows that full-scale pure-oxygen activated sludge (O2-AS) wastewater treatment plants (WWTPs) generate effluents with higher dissolved-organic carbon (DOC) concentrations and larger high-molecular-weight fractions compared to air-activated-sludge (Air-AS) WWTP effluents. The purpose of this paper was to evaluate how gas supplied (air vs. pure oxygen) to sequencing-batch reactors affected DOC transformations. The main conclusions of this paper are (a) O2-AS effluent DOC is more refractory than air-AS effluent DOC; and (b) O2-AS systems may have higher five-day biochemical oxygen demand removals than air-AS systems; however, in terms of COD and DOC removal, air-AS systems are better than O2-AS systems. Analysis of a database from side-by-side O2- and air-AS pilot tests from literature supported these observations. PMID:16629273

  4. Investigation of oxidation resistance of carbon based first-wall liner materials of fusion reactors

    NASA Astrophysics Data System (ADS)

    Moormann, R.; Hinssen, H. K.; Krüssenberg, A.-K.; Stauch, B.; Wu, C. H.

    1994-09-01

    One important aspect in selection of carbon based first-wall liner materials in fusion reactors is a sufficient oxidation resistance against steam and oxygen; this is because during accidents like loss of coolant into vacuum or loss of vacuum these oxidizing media can enter the vacuum vessel and may cause some corrosion of carbon followed by release of adsorbed tritium; in addition other consequences of oxidation like formation of burnable gases and their explosions have to be examined. Based on extensive experience on nuclear graphite oxidation in HTRs KFA has started in cooperation with NET some experimental investigations on oxidation of fusion reactor carbons. Results of first experiments on CFCs, Ti- and Si-doped carbons and graphites in steam (1273-1423 K) and oxygen (973 K) are reported. It was found that most materials have a similar reactivity as HTR nuclear graphites (which is much smaller than those of usual technical carbons); Si-doped CFCs however have a remarkably better oxidation resistance than those, which is probably due to the formation of a protecting layer of SiO 2. The measured kinetic data will be used in safety analyses for above mentioned accidents.

  5. Bacterial reductive dissolution of crystalline Fe(III) oxide in continuous-flow column reactors

    SciTech Connect

    Roden, E.E.; Urrutia, M.M.; Mann, C.J.

    2000-03-01

    Bacterial reductive dissolution of synthetic crystalline Fe(III) oxide-coated sand was studied in continuous-flow column reactors in comparison with parallel batch cultures. The cumulative amount of aqueous Fe(II) exported from the columns over a 6-month incubation period corresponded to (95.0 {+-} 3.7)% (n = 3) of their original Fe(III) content. Wet-chemical analysis revealed that only (6.5 {+-} 3.2)% of the initial Fe(III) content remained in the columns at the end of the experiment. The near-quantitative removal of Fe was visibly evidenced by extensive bleaching of color from the sand in the columns. In contrast to the column reactors, Fe(II) production quickly reached an asymptote in batch cultures, and only (13.0 {+-} 2.2)% (n = 3) of the Fe(III) oxide content was reduced. Sustained bacterial-cell growth occurred in the column reactors, leading to the production and export of a quantity of cells 100-fold greater than that added during inoculation. Indirect estimates of cell growth, based on the quantity of Fe(III) reduced, suggest that only an approximate doubling of initial cell abundance was likely to have occurred in the batch cultures. Their results indicate that removal of biogenic Fe(II) via aqueous-phase transport in the column reactors decreased the passivating influence of surface-bound Fe(II) on oxide reduction activity, thereby allowing a dramatic increase in the extent of Fe(III) oxide reduction and associated bacterial growth. These findings have important implications for understanding the fate of organic and inorganic contaminants whose geochemical behavior is linked to Fe(III) oxide reduction.

  6. Air Quality Criteria for Ozone and Related Photochemical Oxidants (Second External Review Draft)

    EPA Science Inventory

    This second external review draft of the Air Quality Criteria for Ozone and Related Photochemical Oxidants, Volumes I-III (Ozone Criteria Document) is being released for public comment and for review by EPA's Clean Air Scientific Advisory Committee (CASAC) r...

  7. AIR QUALITY CRITERIA FOR OXIDES OF NITROGEN (External Review Draft, 1991)

    EPA Science Inventory

    The revised air quality criteria document for oxides of nitrogen (NOx) reviews and evaluates the scientific information on the health and welfare effects associated with exposure to concentrations of NO2 found in ambient air. Although the document is not intended to be an exhaust...

  8. Effect of fuel-air-ratio nonuniformity on emissions of nitrogen oxides

    NASA Technical Reports Server (NTRS)

    Lyons, V. J.

    1981-01-01

    The inlet fuel-air ratio nonuniformity is studied to deterine how nitrogen oxide (NOx) emissions are affected. An increase in NOx emissions with increased fuel-air ratio nonuniformity for average equivalence ratios less than 0.7 and a decrease in NOx emissions for average equivalence ratios near stoichiometric is predicted. The degree of uniformityy of fuel-air ratio profiles that is necessary to achieve NOx emissions goals for actual engines that use lean, premixed, prevaporized combustion systems is determined.

  9. Oxidation rate of graphitic matrix material in the kinetic regime for VHTR air ingress accident scenarios

    NASA Astrophysics Data System (ADS)

    Lee, Jo Jo; Ghosh, Tushar K.; Loyalka, Sudarshan K.

    2014-08-01

    Data on oxidation rates of matrix-grade graphite in the kinetically-controlled temperature regime of graphite oxidation are needed for safety analysis of High Temperature Gas Cooled Reactors and Very High Temperature Reactors. In this work, the oxidation rate of graphitic matrix material GKrS was measured thermogravimetrically for various oxygen concentrations and with temperatures from 873 to 1873 K. A semi-empirical Arrhenius rate equation was also developed for this temperature range. The activation energy of the graphitic material is found to be about 111.5 kJ/mol. The order of reaction was found to be about 0.89. The surface of oxidized GKrS was characterized by Scanning Electron Microscopy, Electron Dispersive Spectroscopy, Fourier Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy.

  10. DEVELOPMENT OF TRANSITION METAL OXIDE-ZEOLITE CATALYSTS TO CONTROL CHLORINATED VOC AIR EMISSIONS

    EPA Science Inventory

    The paper discusses the development of transition metal oxide (TMO)-zeolite oxidation catalysts to control chlorinated volatile organic compound (CVOC) air emissions. esearch has been initiated to enhance the utility of these catalysts by the development of a sorption-catalyst sy...

  11. Heterogeneous photochemical reactions of a propylene-nitrogen dioxide-metal oxide-dry air system

    NASA Astrophysics Data System (ADS)

    Takeuchi, Koji; Ibusuki, Takashi

    Photochemical reactions of a C 3H 6-NO 2-air system in the presence of metal oxide were investigated. The metal oxides showing strong photooxidation activity were found to be n-type semiconductor oxides with the energy band gap around 3 eV. Formation of cyano-compounds (HCN and CH 3CN) was also observed and the activity can be explained in terms of the adsorptivity of NO onto metal oxides. Coalfired fly ash as a model of mixed metal oxides was also examined and their photocatalytic action was discussed.

  12. Hydrodynamic effects of air sparging on hollow fiber membranes in a bubble column reactor.

    PubMed

    Xia, Lijun; Law, Adrian Wing-Keung; Fane, Anthony G

    2013-07-01

    Air sparging is now a standard approach to reduce concentration polarization and fouling of membrane modules in membrane bioreactors (MBRs). The hydrodynamic shear stresses, bubble-induced turbulence and cross flows scour the membrane surfaces and help reduce the deposit of foulants onto the membrane surface. However, the detailed quantitative knowledge on the effect of air sparging remains lacking in the literature due to the complex hydrodynamics generated by the gas-liquid flows. To date, there is no valid model that describes the relationship between the membrane fouling performance and the flow hydrodynamics. The present study aims to examine the impact of hydrodynamics induced by air sparging on the membrane fouling mitigation in a quantitative manner. A modelled hollow fiber module was placed in a cylindrical bubble column reactor at different axial heights with the trans-membrane pressure (TMP) monitored under constant flux conditions. The configuration of bubble column without the membrane module immersed was identical to that studied by Gan et al. (2011) using Phase Doppler Anemometry (PDA), to ensure a good quantitative understanding of turbulent flow conditions along the column height. The experimental results showed that the meandering flow regime which exhibits high flow instability at the 0.3 m is more beneficial to fouling alleviation compared with the steady flow circulation regime at the 0.6 m. The filtration tests also confirmed the existence of an optimal superficial air velocity beyond which a further increase is of no significant benefit on the membrane fouling reduction. In addition, the alternate aeration provided by two air stones mounted at the opposite end of the diameter of the bubble column was also studied to investigate the associated flow dynamics and its influence on the membrane filtration performance. It was found that with a proper switching interval and membrane module orientation, the membrane fouling can be effectively

  13. AIR QUALITY CRITERIA FOR OXIDES OF NITROGEN (Final, 1993)

    EPA Science Inventory

    This criteria document focuses on a review and assessment of the effects on human health and welfare of the nitrogen oxides, nitric oxide (NO) and nitrogen dioxide (NO2), and the related compounds, nitrites, nitrates, nitrogenous acids, and nitrosamines. Although the emphasis is ...

  14. CONCENTRATED AMBIENT AIR POLLUTION CREATES OXIDATIVE STRESS IN CNS MICROGLIA.

    EPA Science Inventory

    Nanometer size particles carry free radical activity on their surface and can produce oxidative stress (OS)-mediated damage upon impact to target cells. The initiating event of phage cell activation (i.e., the oxidative burst) is unknown, although many proximal events have been i...

  15. Development of an emergency air-cleaning system for liquid-metal reactors

    SciTech Connect

    Owen, R.K.

    1980-11-01

    A novel air cleaning concept has been developed for potential use in venting future commercial liquid metal fast breeder reactor containment buildings in the unlikely event of postulated core disruptive accidents. The passive concept consists of a submerged gravel bed to collect the bulk of particulate contaminates carried by the vented gas. A fibrous scrubber could be combined with the submerged gravel scrubber to enhance collection efficiencies for the smaller sized particles. The submerged gravel scrubber is unique in that water flow through the packed bed is induced by the gas flow, eliminating the need for an active liquid pump. In addition, design gas velocities through the packed bed are 10 to 20 times higher than for a conventional sand bed filter.

  16. Development of a Catalytic Wet Air Oxidation Method to Produce Feedstock Gases from Waste Polymers

    NASA Technical Reports Server (NTRS)

    Kulis, Michael J.; Guerrero-Medina, Karen J.; Hepp, Aloysius F.

    2012-01-01

    Given the high cost of space launch, the repurposing of biological and plastic wastes to reduce the need for logistical support during long distance and long duration space missions has long been recognized as a high priority. Described in this paper are the preliminary efforts to develop a wet air oxidation system in order to produce fuels from waste polymers. Preliminary results of partial oxidation in near supercritical water conditions are presented. Inherent corrosion and salt precipitation are discussed as system design issues for a thorough assessment of a second generation wet air oxidation system. This work is currently being supported by the In-Situ Resource Utilization Project.

  17. Enhanced c2 yields from methane oxidative coupling by means of a separative chemical reactor.

    PubMed

    Tonkovich, A L; Carr, R W; Aris, R

    1993-10-01

    Of the processes for converting natural gas into a more useful chemical feedstock, the oxidative coupling of methane to form ethane and ethylene (C(2)) has perhaps been the most intensively investigated in recent years, but it has proved extremely difficult to obtain C(2) yields in excess of 20 to 25%. Methane oxidative coupling was carried out in a separative chemical reactor that simulated a countercurrent chromatographic moving-bed. This reaction gives 65% methane conversion, 80% C(2) selectivity, and a C(2) yield slightly better than 50% with Sm(2)O(3) catalyst at approximately 1000 K. PMID:17841868

  18. Hydrogen sulfide oxidation in novel Horizontal-Flow Biofilm Reactors dominated by an Acidithiobacillus and a Thiobacillus species.

    PubMed

    Gerrity, S; Kennelly, C; Clifford, E; Collins, G

    2016-09-01

    Hydrogen Sulfide (H2S) is an odourous, highly toxic gas commonly encountered in various commercial and municipal sectors. Three novel, laboratory-scale, Horizontal-Flow Biofilm Reactors (HFBRs) were tested for the removal of H2S gas from air streams over a 178-day trial at 10°C. Removal rates of up to 15.1 g [H2S] m(-3) h(-1) were achieved, demonstrating the HFBRs as a feasible technology for the treatment of H2S-contaminated airstreams at low temperatures. Bio-oxidation of H2S in the reactors led to the production of H(+) and sulfate (SO(2-)4) ions, resulting in the acidification of the liquid phase. Reduced removal efficiency was observed at loading rates of 15.1 g [H2S] m(-3) h(-1). NaHCO3 addition to the liquid nutrient feed (synthetic wastewater (SWW)) resulted in improved H2S removal. Bacterial diversity, which was investigated by sequencing and fingerprinting 16S rRNA genes, was low, likely due to the harsh conditions prevailing in the systems. The HFBRs were dominated by two species from the genus Acidithiobacillus and Thiobacillus. Nonetheless, there were significant differences in microbial community structure between distinct HFBR zones due to the influence of alkalinity, pH and SO4 concentrations. Despite the low temperature, this study indicates HFBRs have an excellent potential to biologically treat H2S-contaminated airstreams. PMID:26829048

  19. Development of DIPRES feed for the fabrication of mixed-oxide fuels for fast breeder reactors

    SciTech Connect

    Griffin, C W; Rasmussen, D E; Lloyd, M H

    1983-01-01

    The DIrect PREss Spheroidized feed process combines the conversion of uranium-plutonium solutions into spheres by internal gelation with conventional pellet fabrication techniques. In this manner, gel spheres could replace conventional powders as the feed material for pellet fabrication of nuclear fuels. Objective of the DIPRES feed program is to develop and qualify a process to produce mixed-oxide fuel pellets from gel spheres for fast breeder reactors. This process development includes both conversion and fabrication activities.

  20. Isotopic evidence for nitrous oxide production pathways in a partial nitritation-anammox reactor.

    PubMed

    Harris, Eliza; Joss, Adriano; Emmenegger, Lukas; Kipf, Marco; Wolf, Benjamin; Mohn, Joachim; Wunderlin, Pascal

    2015-10-15

    Nitrous oxide (N2O) production pathways in a single stage, continuously fed partial nitritation-anammox reactor were investigated using online isotopic analysis of offgas N2O with quantum cascade laser absorption spectroscopy (QCLAS). N2O emissions increased when reactor operating conditions were not optimal, for example, high dissolved oxygen concentration. SP measurements indicated that the increase in N2O was due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor. The results of this study confirm that process control via online N2O monitoring is an ideal method to detect imbalances in reactor operation and regulate aeration, to ensure optimal reactor conditions and minimise N2O emissions. Under normal operating conditions, the N2O isotopic site preference (SP) was much higher than expected - up to 40‰ - which could not be explained within the current understanding of N2O production pathways. Various targeted experiments were conducted to investigate the characteristics of N2O formation in the reactor. The high SP measurements during both normal operating and experimental conditions could potentially be explained by a number of hypotheses: i) unexpectedly strong heterotrophic N2O reduction, ii) unknown inorganic or anammox-associated N2O production pathway, iii) previous underestimation of SP fractionation during N2O production from NH2OH, or strong variations in SP from this pathway depending on reactor conditions. The second hypothesis - an unknown or incompletely characterised production pathway - was most consistent with results, however the other possibilities cannot be discounted. Further experiments are needed to distinguish between these hypotheses and fully resolve N2O production pathways in PN-anammox systems. PMID:26164660

  1. Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

    NASA Astrophysics Data System (ADS)

    Uddi, M.; Jiang, N.; Adamovich, I. V.; Lempert, W. R.

    2009-04-01

    Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ~8 × 1012 cm-3 (~4.14 ppm) occurring at ~250 µs after the pulse, with decay time of ~16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of phiv = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of phiv = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N2(C 3Π) and NO(A 2Σ) in air at P = 60 Torr decay within ~20 ns and ~1 µs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (~100 µs) metastable states, such as N2(X 1Σ,v) and O2(b 1Σ), formed by quenching of the metastable N2(A 3Σ) state by ground electronic state O2, may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O2, as well as by conversion into NO2 in a reaction of NO with ozone.

  2. Oxidation mechanisms of CF2Br2 and CH2Br2 induced by air nonthermal plasma.

    PubMed

    Schiorlin, Milko; Marotta, Ester; Dal Molin, Marta; Paradisi, Cristina

    2013-01-01

    Oxidation mechanisms in air nonthermal plasma (NTP) at room temperature and atmospheric pressure were investigated in a corona reactor energized by +dc, -dc, or +pulsed high voltage.. The two bromomethanes CF(2)Br(2) and CH(2)Br(2) were chosen as model organic pollutants because of their very different reactivities with OH radicals. Thus, they served as useful mechanistic probes: they respond differently to the presence of humidity in the air and give different products. By FT-IR analysis of the postdischarge gas the following products were detected and quantified: CO(2) and CO in the case of CH(2)Br(2), CO(2) and F(2)C ═ O in the case of CF(2)Br(2). F(2)C ═ O is a long-lived oxidation intermediate due to its low reactivity with atmospheric radicals. It is however removed from the NTP processed gas by passage through a water scrubber resulting in hydrolysis to CO(2) and HF. Other noncarbon containing products of the discharge were also monitored by FT-IR analysis, including HNO(3) and N(2)O. Ozone, an important product of air NTP, was never detected in experiments with CF(2)Br(2) and CH(2)Br(2) because of the highly efficient ozone depleting cycles catalyzed by BrOx species formed from the bromomethanes. It is concluded that, regardless of the type of corona applied, CF(2)Br(2) reacts in air NTP via a common intermediate, the CF(2)Br radical. The possible reactions leading to this radical are discussed, including, for -dc activation, charge exchange with O(2)(-), a species detected by APCI mass spectrometry. PMID:23190335

  3. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  4. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  5. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  6. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  7. Air Oxidation of Activated Carbon to Synthesize a Biomimetic Catalyst for Hydrolysis of Cellulose.

    PubMed

    Shrotri, Abhijit; Kobayashi, Hirokazu; Fukuoka, Atsushi

    2016-06-01

    Oxygenated carbon catalyzes the hydrolysis of cellulose present in lignocellulosic biomass by utilizing the weakly acidic functional groups on its surface. Here we report the synthesis of a biomimetic carbon catalyst by simple and economical air-oxidation of a commercially available activated carbon. Air- oxidation at 450-500 °C introduced 2000-2400 μmol g(-1) of oxygenated functional groups on the material with minor changes in the textural properties. Selectivity towards the formation of carboxylic groups on the catalyst surface increased with the increase in oxidation temperature. The degree of oxidation on carbon catalyst was found to be proportional to its activity for hydrolysis of cellulose. The hydrolysis of eucalyptus in the presence of carbon oxidized at 475 °C afforded glucose yield of 77 % and xylose yield of 67 %. PMID:27115288

  8. A review of wet air oxidation and Thermal Hydrolysis technologies in sludge treatment.

    PubMed

    Hii, Kevin; Baroutian, Saeid; Parthasarathy, Raj; Gapes, Daniel J; Eshtiaghi, Nicky

    2014-03-01

    With rapid world population growth and strict environmental regulations, increasingly large volumes of sludge are being produced in today's wastewater treatment plants (WWTP) with limited disposal routes. Sludge treatment has become an essential process in WWTP, representing 50% of operational costs. Sludge destruction and resource recovery technologies are therefore of great ongoing interest. Hydrothermal processing uses unique characteristics of water at elevated temperatures and pressures to deconstruct organic and inorganic components of sludge. It can be broadly categorized into wet oxidation (oxidative) and thermal hydrolysis (non-oxidative). While wet air oxidation (WAO) can be used for the final sludge destruction and also potentially producing industrially useful by-products such as acetic acid, thermal hydrolysis (TH) is mainly used as a pre-treatment method to improve the efficiency of anaerobic digestion. This paper reviews current hydrothermal technologies, roles of wet air oxidation and thermal hydrolysis in sludge treatment, and challenges faced by these technologies. PMID:24457302

  9. Quantitative Analysis of Major Phytochemicals in Orthodox tea (Camellia sinensis), Oxidized under Compressed Air Environment.

    PubMed

    Panda, Brajesh Kumar; Datta, Ashis Kumar

    2016-04-01

    This study describes major changes in phytochemical composition of orthodox tea (Camellia sinensis var. Assamica) oxidized under compressed air (CA). The experiments for oxidation were conducted under air pressure (101, 202, and 303 kPa) for 150 min. Relative change in the concentrations of caffeine, catechins, theaflavins (TF), and thearubigins (TR) were analyzed. Effect of CA pressure was found to be nonsignificant in regulating caffeine concentration during oxidation. But degradation in different catechins as well as formation of different TF was significantly affected by CA pressure. At high CA pressure, TF showed highest peak value. TR was found to have slower rate of formation during initial phase of oxidation than TF. Even though the rate of TR formation was significantly influenced by CA, a portion of catechins remained unoxidized at end of oxidation. Except caffeine, the percent change in rate of formation or degradation were more prominent at 202 kPa. PMID:26970442

  10. Microlith-Based Catalytic Reactor for Air Quality and Trace Contaminant Control Applications

    NASA Technical Reports Server (NTRS)

    Vilekar, Saurabh; Hawley, Kyle; Junaedi, Christian; Crowder, Bruce; Prada, Julian; Mastanduno, Richard; Perry, Jay L.; Kayatin, Matthew J.

    2015-01-01

    Traditionally, gaseous compounds such as methane, carbon monoxide, and trace contaminants have posed challenges for maintaining clean air in enclosed spaces such as crewed spacecraft cabins as they are hazardous to humans and are often difficult to remove by conventional adsorption technology. Catalytic oxidizers have provided a reliable and robust means of disposing of even trace levels of these compounds by converting them into carbon dioxide and water. Precision Combustion, Inc. (PCI) and NASA - Marshall (MSFC) have been developing, characterizing, and optimizing high temperature catalytic oxidizers (HTCO) based on PCI's patented Microlith® technology to meet the requirements of future extended human spaceflight explorations. Current efforts have focused on integrating the HTCO unit with a compact, simple recuperative heat exchanger to reduce the overall system size and weight while also reducing its energy requirements. Previous efforts relied on external heat exchangers to recover the waste heat and recycle it to the oxidizer to minimize the system's power requirements; however, these units contribute weight and volume burdens to the overall system. They also result in excess heat loss due to the separation of the HTCO and the heat recuperator, resulting in lower overall efficiency. Improvements in the recuperative efficiency and close coupling of HTCO and heat recuperator lead to reductions in system energy requirements and startup time. Results from testing HTCO units integrated with heat recuperators at a variety of scales for cabin air quality control and heat melt compactor applications are reported and their benefits over previous iterations of the HTCO and heat recuperator assembly are quantified in this paper.

  11. NUCLEAR REACTOR

    DOEpatents

    Christy, R.F.

    1958-07-15

    A nuclear reactor of the homogeneous liquid fuel type is described wherein the fissionable isotope is suspended or dissolved in a liquid moderator such as water. The reactor core is comprised essentially of a spherical vessel for containing the reactive composition surrounded by a reflector, preferably of beryllium oxide. The reactive composition may be an ordinary water solution of a soluble salt of uranium, the quantity of fissionable isotope in solution being sufficient to provide a critical mass in the vessel. The liquid fuel is stored in a tank of non-crtttcal geometry below the reactor vessel and outside of the reflector and is passed from the tank to the vessel through a pipe connecting the two by air pressure means. Neutron absorbing control and safety rods are operated within slots in the reflector adjacent to the vessel.

  12. Investigating the air oxidation of V(II) ions in a vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Ngamsai, Kittima; Arpornwichanop, Amornchai

    2015-11-01

    The air oxidation of vanadium (V(II)) ions in a negative electrolyte reservoir is a major side reaction in a vanadium redox flow battery (VRB), which leads to electrolyte imbalance and self-discharge of the system during long-term operation. In this study, an 80% charged negative electrolyte solution is employed to investigate the mechanism and influential factors of the reaction in a negative-electrolyte reservoir. The results show that the air oxidation of V(II) ions occurs at the air-electrolyte solution interface area and leads to a concentration gradient of vanadium ions in the electrolyte solution and to the diffusion of V(II) and V(III) ions. The effect of the ratio of the electrolyte volume to the air-electrolyte solution interface area and the concentrations of vanadium and sulfuric acid in an electrolyte solution is investigated. A higher ratio of electrolyte volume to the air-electrolyte solution interface area results in a slower oxidation reaction rate. The high concentrations of vanadium and sulfuric acid solution also retard the air oxidation of V(II) ions. This information can be utilized to design an appropriate electrolyte reservoir for the VRB system and to prepare suitable ingredients for the electrolyte solution.

  13. TASK TECHNICAL AND QUALITY ASSURANCE PLAN FOR OUT-OF-TANK DESTRUCTION OF TETRAPHENYLBORATE VIA WET AIR OXIDATION TECHNOLOGY: PHASE I - BENCH SCALE TESTS

    SciTech Connect

    Adu-Wusu, K

    2006-03-31

    injected into the pressurized waste stream, and the air/liquid mixture is preheated to the required reactor inlet temperature. The reactor provides sufficient retention time to allow the oxidation to approach the desired level of organic decomposition. Typical reaction time is about 30-120 minutes. Heat exchangers are routinely employed to recover energy contained in the reactor effluent to preheat the waste feed/air entering the reactor. Auxiliary energy, usually steam, is necessary for startup and can provide trim heat if required. Since the oxidation reactions are exothermic, sufficient energy may be released in the reactor to allow the WAO system to operate without any additional heat input. After cooling, the oxidized reactor effluent passes through a pressure control valve where the pressure is reduced. A separator downstream of the pressure control valve allows the depressurized and cooled vapor to separate from the liquid. Typical industrial WAO applications have a feed flow rate of 1 to 220 gallons per minute (gpm) per train, with a chemical oxygen demand (COD) from 10,000 to 150,000 mg/L (higher CODs with dilution). Note that catalysts, such as homogeneous copper and iron, their heterogeneous counterparts, or precious metals can be used to enhance the effectiveness (i.e., to lower temperature, pressure, and residence time as well as increase oxidation efficiencies) of the WAO reaction if deemed necessary.

  14. Influence of fission products on ruthenium oxidation and transport in air ingress nuclear accidents

    NASA Astrophysics Data System (ADS)

    Vér, N.; Matus, L.; Kunstár, M.; Osán, J.; Hózer, Z.; Pintér, A.

    2010-01-01

    In separate effect tests at 1000-1200 °C Ru oxidation rate and content of Ru in escaping air flow have been studied with special emphasis on effects of other fission product elements on the Ru oxidation and transport. The results showed that in the decreasing temperature section (1100-600 °C) most of the RuO3 and RuO4 (≈95%) decomposed and formed RuO2 crystals; while the partial pressure of RuO4 in the escaping air was in the range of 10-6 bar. The re-evaporation of deposited RuO2 resulted in about 10-6 bar partial pressure in the outlet gas as well. Measurements demonstrated the importance of surface quality in the decreasing temperature area on the heterogeneous phase decomposition of ruthenium oxides to RuO2. On the other hand water or molybdenum oxide vapour in air appears to decrease the surface catalyzed decomposition of RuOx to RuO2 and increases RuO4 concentration in the escaping air. High temperature reaction with caesium changed the form of the released ruthenium and caused a time delay in appearance of maximum concentration of ruthenium oxides in the ambient temperature escaping gas, while reaction with barium and rare earth oxides extended Ru escape from the high temperature area.

  15. Differences between the oxidation behaviour of A3 fuel element matrix graphites in air and in steam and its relevance on accident progress in HTRs

    SciTech Connect

    Kuehn, K.; Hinssen, H-K.; Moormann, R.

    2004-07-01

    The fuel element matrix graphites A3-3 and A3-27 were used in High Temperature Reactor fuel pebbles for many years. However, these materials show as other graphites a limited oxidation resistance in contact to oxidising gases (air and steam), which even decreases with increasing temperatures: In HTRs, having in normal operation a non-oxidising environment, an ingress of air or steam leads to corrosion of graphite with the potential of enhanced fission product release Matrix graphites differ by its coked binder content from standard nuclear graphites (e.g. V483T, ASR-1RG, IG110, H-451), where both filler and binder are completely graphitized. The influence of this coked binder content on the oxidation behaviour will be discussed in this paper. Experimental investigations with A3-3 and A3-27 were done in oxygen (air) at temperatures between 673 - 1023 K and in steam between 1173 - 1253 K. These experiments took place under isothermal conditions in the chemical regime, where the chemical reaction itself is the rate limiting step and a homogeneous oxidation inside of the sample occurs. The experiments reveal different oxidation behaviour as well between binder and filler component as between oxidation behaviour in oxygen (air) and steam. In air at low temperatures two rate maxima are observed: The first maximum attend in all experiments at {approx} 5 % burn off, a second one at higher burn off values (35 - 45 % burn off). These rate maxima can be explained by a selective binder-filler oxidation: The first peak at 5 % burn off is due to the oxidation of the binder, the second peak at higher burn off values is caused by the oxidation of the remaining filler. At higher temperatures in air the filler peak becomes more pronounced and the binder peak vanishes, which is due to the lower activation energy of binder oxidation compared to the filler. In steam this behaviour appears contrary: A maximum at 5 % burn off, which is probably also connected to the binder, is observed

  16. Sulfidation of mixed metal oxides in a fluidized-bed reactor

    SciTech Connect

    Christoforou, S.C.; Efthimiadis, E.A.; Vasalos, I.A. )

    1995-01-01

    Mixed metal oxides were used for the removal of hydrogen sulfide from a hot gas stream. Sorbents were prepared according to the dry and wet impregnation techniques. The desulfurization performance of the metal oxide sorbents was experimentally tested in a fluidized-bed reactor system. Sulfidation experiments performed under reaction conditions similar to those at the exit of a coal gasifier showed that the preparation procedure and technique, the type and the amount of the impregnated metal oxide, the type of the solid carrier, and the size of the solid reactant affect the H[sub 2]S removal capacity of the sorbents. The pore structure of fresh and sulfided sorbents was analyzed using mercury porosimetry, nitrogen adsorption, and scanning electron microscopy.

  17. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    PubMed

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance. PMID:26393523

  18. The behaviour of transuranic mixed oxide fuel in a Candu-900 reactor

    SciTech Connect

    Morreale, A. C.; Ball, M. R.; Novog, D. R.; Luxat, J. C.

    2012-07-01

    The production of transuranic actinide fuels for use in current thermal reactors provides a useful intermediary step in closing the nuclear fuel cycle. Extraction of actinides reduces the longevity, radiation and heat loads of spent material. The burning of transuranic fuels in current reactors for a limited amount of cycles reduces the infrastructure demand for fast reactors and provides an effective synergy that can result in a reduction of as much as 95% of spent fuel waste while reducing the fast reactor infrastructure needed by a factor of almost 13.5 [1]. This paper examines the features of actinide mixed oxide fuel, TRUMOX, in a CANDU{sup R}* nuclear reactor. The actinide concentrations used were based on extraction from 30 year cooled spent fuel and mixed with natural uranium in 3.1 wt% actinide MOX fuel. Full lattice cell modeling was performed using the WIMS-AECL code, super-cell calculations were analyzed in DRAGON and full core analysis was executed in the RFSP 2-group diffusion code. A time-average full core model was produced and analyzed for reactor coefficients, reactivity device worth and online fuelling impacts. The standard CANDU operational limits were maintained throughout operations. The TRUMOX fuel design achieved a burnup of 27.36 MWd/kg HE. A full TRUMOX fuelled CANDU was shown to operate within acceptable limits and provided a viable intermediary step for burning actinides. The recycling, reprocessing and reuse of spent fuels produces a much more sustainable and efficient nuclear fuel cycle. (authors)

  19. 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.

  20. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  1. Ozone generation by negative direct current corona discharges in dry air fed coaxial wire-cylinder reactors

    SciTech Connect

    Yehia, Ashraf; Mizuno, Akira

    2013-05-14

    An analytical study was made in this paper for calculating the ozone generation by negative dc corona discharges. The corona discharges were formed in a coaxial wire-cylinder reactor. The reactor was fed by dry air flowing with constant rates at atmospheric pressure and room temperature, and stressed by a negative dc voltage. The current-voltage characteristics of the negative dc corona discharges formed inside the reactor were measured in parallel with concentration of the generated ozone under different operating conditions. An empirical equation was derived from the experimental results for calculating the ozone concentration generated inside the reactor. The results, that have been recalculated by using the derived equation, have agreed with the experimental results over the whole range of the investigated parameters, except in the saturation range for the ozone concentration. Therefore, the derived equation represents a suitable criterion for expecting the ozone concentration generated by negative dc corona discharges in dry air fed coaxial wire-cylinder reactors under any operating conditions in range of the investigated parameters.

  2. Nano-textured copper oxide nanofibers for efficient air cooling

    NASA Astrophysics Data System (ADS)

    An, Seongpil; Jo, Hong Seok; Al-Deyab, Salem S.; Yarin, Alexander L.; Yoon, Sam S.

    2016-02-01

    Ever decreasing of microelectronics devices is challenged by overheating and demands an increase in heat removal rate. Herein, we fabricated highly efficient heat-removal coatings comprised of copper oxide-plated polymer nanofiber layers (thorny devil nanofibers) with high surface-to-volume ratio, which facilitate heat removal from the underlying hot surfaces. The electroplating time and voltage were optimized to form fiber layers with maximal heat removal rate. The copper oxide nanofibers with the thorny devil morphology yielded a superior cooling rate compared to the pure copper nanofibers with the smooth surface morphology. This superior cooling performance is attributed to the enhanced surface area of the thorny devil nanofibers. These nanofibers were characterized with scanning electron microscopy, X-ray diffraction, atomic force microscopy, and a thermographic camera.

  3. Stability and nitrite-oxidizing bacteria community structure in different high-rate CANON reactors.

    PubMed

    Liang, Yuhai; Li, Dong; Zhang, Xiaojing; Zeng, Huiping; Yang, Zhuo; Cui, Shaoming; Zhang, Jie

    2015-01-01

    In completely autotrophic nitrogen removal over nitrite (CANON) process, the bioactivity of nitrite-oxidizing bacteria (NOB) should be effectively inhibited. In this study, the stability of four high-rate CANON reactors and the effect of free ammonia (FA) and organic material on NOB community structure were investigated using DGGE. Results suggested that with the increasing of FA, the ratio of total nitrogen removal to nitrate production went up gradually, while the biodiversity of Nitrobacter-like NOB and Nitrospira-like NOB both decreased. When the CANON reactor was transformed to simultaneous partial nitrification, anammox and denitrification (SNAD) reactor by introducing organic material, the denitrifiers and aerobic heterotrophic bacteria would compete nitrite or oxygen with NOB, which then led to the biodiversity decreasing of both Nitrobacter-like NOB and Nitrospira-like NOB. The distribution of Nitrobacter-like NOB and Nitrospira-like NOB were evaluated, and finally effective strategies for suppressing NOB in CANON reactors were proposed. PMID:25459821

  4. Air oxidation of d-limonene (the citrus solvent) creates potent allergens.

    PubMed

    Karlberg, A T; Magnusson, K; Nilsson, U

    1992-05-01

    Products containing as much as 95% of d-limonene are used for, e.g., degreasing metal before industrial painting and for cleaning assemblies. Experimental studies on the sensitizing potential of limonene show diverging results. In a previous study, we found that the sensitizing potential of d-limonene increased with prolonged air exposure. The aim of this study was to make further chemical analyses, to identify compounds formed by air exposure of d-limonene and to study their allergenic potential. d-limonene was found to be a sensitizer after prolonged exposure to air according to 2 Freund's complete adjuvant test (FCAT) experiments and 1 guinea pig maximization test (GPMT) study. No significant response was obtained to d-limonene not air exposed, even if the animals were sensitized to oxidized d-limonene. 5 main oxidation products of d-limonene were identified. (R)-(-)-carvone and a mixture of cis and trans isomers of (+)-limonene oxide were found to be potent sensitizers, while no significant reactions were obtained in the animals induced with a mixture of cis and trans isomers of (-)-carveol. It can be concluded that air oxidation of d-limonene is essential for its sensitizing potential, and that potent allergens are created. PMID:1395597

  5. Mild and selective vanadium-catalyzed oxidation of benzylic, allylic, and propargylic alcohols using air.

    PubMed

    Hanson, Susan K; Wu, Ruilian; Silks, L A Pete

    2011-04-15

    Transition metal-catalyzed aerobic alcohol oxidation is an attractive method for the synthesis of carbonyl compounds, but most catalytic systems feature precious metals and require pure oxygen. The vanadium complex (HQ)(2)V(V)(O)(O(i)Pr) (2 mol %, HQ = 8-quinolinate) and NEt(3) (10 mol %) catalyze the oxidation of benzylic, allylic, and propargylic alcohols with air. The catalyst can be easily prepared under air using commercially available reagents and is effective for a wide range of primary and secondary alcohols. PMID:21434606

  6. Modeling Geometric Arrangements of TiO2-Based Catalyst Substrates and Isotropic Light Sources to Enhance the Efficiency of a Photocatalystic Oxidation (PCO) Reactor

    NASA Technical Reports Server (NTRS)

    Richards, Jeffrey T.; Levine, Lanfang H.; Husk, Geoffrey K.

    2011-01-01

    The closed confined environments of the ISS, as well as in future spacecraft for exploration beyond LEO, provide many challenges to crew health. One such challenge is the availability of a robust, energy efficient, and re-generable air revitalization system that controls trace volatile organic contaminants (VOCs) to levels below a specified spacecraft maximum allowable concentration (SMAC). Photocatalytic oxidation (PCO), which is capable of mineralizing VOCs at room temperature and of accommodating a high volumetric flow, is being evaluated as an alternative trace contaminant control technology. In an architecture of a combined air and water management system, placing a PCO unit before a condensing heat exchanger for humidity control will greatly reduce the organic load into the humidity condensate loop ofthe water processing assembly (WPA) thereby enhancing the life cycle economics ofthe WPA. This targeted application dictates a single pass efficiency of greater than 90% for polar VOCs. Although this target was met in laboratory bench-scaled reactors, no commercial or SBIR-developed prototype PCO units examined to date have achieved this goal. Furthermore, the formation of partial oxidation products (e.g., acetaldehyde) was not eliminated. It is known that single pass efficiency and partial oxidation are strongly dependent upon the contact time and catalyst illumination, hence the requirement for an efficient reactor design. The objective of this study is to maximize the apparent contact time and illuminated catalyst surface area at a given reactor volume and volumetric flow. In this study, a Ti02-based photocatalyst is assumed to be immobilized on porous substrate panels and illumination derived from linear isotropic light sources. Mathematical modeling using computational fluid dynamics (CFD) analyses were performed to investigate the effect of: 1) the geometry and configuration of catalyst-coated substrate panels, 2) porosity of the supporting substrate, and 3

  7. Studies on the regeneration of sulfided iron oxide sorbent with steam-air mixtures. Final technical report

    SciTech Connect

    Tamhankar, S.S.

    1982-10-01

    The work reported here was performed as a continuation of studies conducted previously at West Virginia University (WVU), Department of Chemical Engineering on a hot-fuel-gas desulfurization process using a regenerable iron oxide-silica sorbent. The overall process consists of two stages: the absorption or the H/sub 2/S removal stage and the sorbent regeneration stage. In the absorption stage the iron oxide reacts with H/sub 2/S to form iron sulfide. For regeneration of the sulfided sorbent, various schemes have been proposed. Studies at WVU have been aimed at identifying the important reactions involved in absorption and regeneration stages, elucidating their mechanisms and investigating detailed kinetics. In the first two phases of the study, reactions in H/sub 2/S absorption and in sorbent regeneration by air/SO/sub 2/ were investigated. This report addresses regeneration of the sulfided sorbent using steam-air mixtures. Experiments were conducted in a thermo-gravimetric analyzer (TGA) apparatus. The weight changes were recorded as a function of time during the reactions of iron sulfide (in the presulfided sorbent) with nitrogen-stream and air-steam mixtures. In addition, several solid samples at different conversion levels were anlayzed by LECO sulfur anlaysis technique and by Mossbauer spectroscopy. Based on these results, a reaction mechanism has been postulated. Additional work is necessary to investigate the gas-phase reactions which may be taking place simultaneously in a fixed - or a fluidized-bed reactor, and to formulate the overall reaction scheme. 14 figures, 3 tables.

  8. Nano-Fenton Reactors as a New Class of Oxidative Stress Amplifying Anticancer Therapeutic Agents.

    PubMed

    Kwon, Byeongsu; Han, Eunji; Yang, Wonseok; Cho, Wooram; Yoo, Wooyoung; Hwang, Junyeon; Kwon, Byoung-Mog; Lee, Dongwon

    2016-03-01

    Cancer cells, compared to normal cells, are under oxidative stress associated with an elevated level of reactive oxygen species (ROS) and are more vulnerable to oxidative stress induced by ROS generating agents. Thus, manipulation of the ROS level provides a logical approach to kill cancer cells preferentially, without significant toxicity to normal cells, and great efforts have been dedicated to the development of strategies to induce cytotoxic oxidative stress for cancer treatment. Fenton reaction is an important biological reaction in which irons convert hydrogen peroxide (H2O2) to highly toxic hydroxyl radicals that escalate ROS stress. Here, we report Fenton reaction-performing polymer (PolyCAFe) micelles as a new class of ROS-manipulating anticancer therapeutic agents. Amphiphilic PolyCAFe incorporates H2O2-generating benzoyloxycinnamaldehyde and iron-containing compounds in its backbone and self-assembles to form micelles that serve as Nano-Fenton reactors to generate cytotoxic hydroxyl radicals, killing cancer cells preferentially. When intravenously injected, PolyCAFe micelles could accumulate in tumors preferentially to remarkably suppress tumor growth, without toxicity to normal tissues. This study demonstrates the tremendous translatable potential of Nano-Fenton reactors as a new class of anticancer drugs. PMID:26888039

  9. Cr(VI) reduction coupled with anaerobic oxidation of methane in a laboratory reactor.

    PubMed

    Lu, Yong-Ze; Fu, Liang; Ding, Jing; Ding, Zhao-Wei; Li, Na; Zeng, Raymond J

    2016-10-01

    The process of anaerobic oxidation of methane (AOM) is globally important because of its contribution to the carbon cycle in the environment. Besides, microorganisms play important roles in the environmental fate of chromium. However, there have been no studies to date on the interaction between methane and chromium in batch reactor systems. In this study, biological Cr(VI) reduction was investigated using methane as the sole electron donor. Isotopic (13)CH4 in the batch experiments and long-term performance in the reactor demonstrated that Cr(VI) reduction is coupled with methane oxidation. High-throughput sequencing of the 16S rRNA genes demonstrated that the microbial community had changed substantially after Cr(VI) reduction. The populations of ANME-2d archaea were enhanced, and they became the only predominant AOM-related microbe. Interestingly, other bacteria with significant increases in abundance were not reported as having the ability to reduce Cr(VI). According to these results, two mechanisms were proposed: 1) Cr(VI) is reduced by ANME-2d alone; 2) Cr(VI) is reduced by unknown Cr(VI)-reducing microbes coupled with ANME-2d. This study revealed the potential relationship between Cr(VI) reduction and CH4 oxidation, and extended our knowledge of the relationship between the AOM process and biogeochemical cycles. PMID:27395029

  10. High temperature CO2 capture using calcium oxide sorbent in a fixed-bed reactor.

    PubMed

    Dou, Binlin; Song, Yongchen; Liu, Yingguang; Feng, Cong

    2010-11-15

    The gas-solid reaction and breakthrough curve of CO(2) capture using calcium oxide sorbent at high temperature in a fixed-bed reactor are of great importance, and being influenced by a number of factors makes the characterization and prediction of these a difficult problem. In this study, the operating parameters on reaction between solid sorbent and CO(2) gas at high temperature were investigated. The results of the breakthrough curves showed that calcium oxide sorbent in the fixed-bed reactor was capable of reducing the CO(2) level to near zero level with the steam of 10 vol%, and the sorbent in CaO mixed with MgO of 40 wt% had extremely low capacity for CO(2) capture at 550°C. Calcium oxide sorbent after reaction can be easily regenerated at 900°C by pure N(2) flow. The experimental data were analyzed by shrinking core model, and the results showed reaction rates of both fresh and regeneration sorbents with CO(2) were controlled by a combination of the surface chemical reaction and diffusion of product layer. PMID:20724072

  11. Effects of ambient oxidant air pollution in the San Joaquin Valley on Thompson seedless grapes

    SciTech Connect

    Brewer, R.F.; Ashcroft, R.

    1984-01-01

    Mature Thompson seedless grape vines were enclosed in specially constructed plastic covered chambers supplied with carbon filtered and non-filtered (ambient) air from time of bud break through leaf drop. Effects on vegetative growth and fruiting were determined for three seasons. No effects on fruit production were measured the first season after covering but vegetative growth increased 12% in chambers supplied with filtered air. By the third season fruit yields were 27.5% higher in the filtered as compared with ambient chambers. The only visible symptoms associated with exposure to the oxidants was accelerated senescence which appeared 3 weeks to 1 month earlier on vines receiving ambient or nonfiltered air.

  12. Development of the Monolith Froth Reactor for Catalytic Wet Oxidation of CELSS Model Wastes

    NASA Technical Reports Server (NTRS)

    Abraham, Martin; Fisher, John W.

    1995-01-01

    The aqueous phase oxidation of acetic acid, used as a model compound for the treatment of CELSS (Controlled Ecological Life Support System) waste, was carried out in the monolith froth reactor which utilizes two-phase flow in the monolith channels. The catalytic oxidation of acetic acid was carried out over a Pt/Al2O3 catalyst, prepared at The University of Tulsa, at temperatures and pressures below the critical point of water. The effect of externally controllable parameters (temperature, liquid flow rate, distributor plate orifice size, pitch, and catalyst distance from the distributor plate) on the rate of acetic acid oxidation was investigated. Results indicate reaction rate increased with increasing temperature and exhibited a maximum with respect to liquid flow rate. The apparent activation energy calculated from reaction rate data was 99.7 kJ/mol. This value is similar to values reported for the oxidation of acetic acid in other systems and is comparable to intrinsic values calculated for oxidation reactions. The kinetic data were modeled using simple power law kinetics. The effect of "froth" feed system characteristics was also investigated. Results indicate that the reaction rate exhibits a maximum with respect to distributor plate orifice size, pitch, and catalyst distance from the distributor plate. Fundamental results obtained were used to extrapolate where the complete removal of acetic acid would be obtained and for the design and operation of a full scale CELSS treatment system.

  13. Development of the Monolith Froth Reactor for Catalytic Wet Oxidation of CELSS Model Wastes

    NASA Technical Reports Server (NTRS)

    Fisher, John W.; Abraham, Martin

    1993-01-01

    The aqueous phase oxidation of acetic acid, used as a model compound for the treatment of CELSS (Controlled Ecological Life Support System) waste, was carried out in the monolith froth reactor which utilizes two-phase flow in the monolith channels. The catalytic oxidation of acetic acid was carried out over a Pt/Al2O3 catalyst at temperatures and pressures below the critical point of water. The effect of externally controllable parameters (temperature, liquid flow rate, distributor plate orifice size, pitch, and catalyst distance from the distributor plate) on the rate of acetic acid oxidation was investigated. Results indicate reaction rate increased with increasing temperature and exhibited a maximum with respect to liquid flow rate. The apparent activation energy calculated from reaction rate data was 99.7 kJ/mol. This value is similar to values reported for the oxidation of acetic acid in other systems and is comparable to intrinsic values calculated for oxidation reactions. The kinetic data were modeled using simple power law kinetics. The effect of "froth" feed system characteristics was also investigated. Results indicate that the reaction rate exhibits a maximum with respect to distributor plate orifice size, pitch, and catalyst distance from the distributor plate. Fundamental results obtained were used to extrapolate where the complete removal of acetic acid would be obtained and for the design and operation of a full scale CELSS treatment system.

  14. [Removal of Cr from tannery sludge by bioleaching in air-lift reactor: a pilot study].

    PubMed

    Chen, Hao; Zhou, Li-xiang; Li, Chao

    2007-09-01

    A bioleaching process performed in 280 L air-lift reactor was developed for extracting Cr from tannery sludge. Cr removal efficiency under different aeration amount with a range from 1.0 m3/h to 3.0 m3/h was investigated. The results showed that the sludge could be homogeneous quickly for different aeration treatment even if aeration amount was as low as 1.0 m3/h. But the obvious effect of aeration amount on pH decrease and subsequent Cr dissolution in tannery sludge during bioleaching was observed. If the aeration amount was below 1.5 m3/h, it at least took 90 h to reach 80% Cr removal efficiency. In the light of Cr removal efficiency and energy consume, the aeration amount of 2.0 m3/h was considered as an optimum one for bioleaching in this trial. Cr removal efficiency could reach above 92.5% at 72 h. In the sludge bioleaching system dissolved oxygen increased obviously with the decrease of pH. Eventually, dissolved oxygen rised to 5 mg/L or more when aeration amount was maintained at 2.0 m3/h or more. Therefore, it was suggested that the aeration amount in ALR could be adjusted to a lower level in the late stage of tannery sludge bioleaching in order to save operation cost. PMID:17990555

  15. Synthesis and characterization of carbon black/manganese oxide air cathodes for zinc-air batteries

    NASA Astrophysics Data System (ADS)

    Li, Po-Chieh; Hu, Chi-Chang; Lee, Tai-Chou; Chang, Wen-Sheng; Wang, Tsin Hai

    2014-12-01

    Due to the poor electric conductivity but the excellent catalytic ability for the oxygen reduction reaction (ORR), manganese dioxide in the α phase (denoted as α-MnO2) anchored onto carbon black powders (XC72) has been synthesized by the reflux method. The specific surface area and electric conductivity of the composites are generally enhanced by increasing the XC72 content while the high XC72 content will induce the formation of MnOOH which shows a worse ORR catalytic ability than α-MnO2. The ORR activity of such air cathodes have been optimized at the XC72/α-MnO2 ratio equal to 1 determined by the thermogravimetric analysis. By using this optimized cathode under the air atmosphere, the quasi-steady-state full-cell discharge voltages are equal to 1.353 and 1.178 V at 2 and 20 mA cm-2, respectively. Due to the usage of ambient air rather than pure oxygen, this Zn-air battery shows a modestly high discharge peak power density (67.51 mW cm-2) meanwhile the power density is equal to 47.22 mW cm-2 and the specific capacity is more than 750 mAh g-1 when this cell is operated at 1 V.

  16. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-11-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality.

  17. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region.

    PubMed

    Oikawa, P Y; Ge, C; Wang, J; Eberwein, J R; Liang, L L; Allsman, L A; Grantz, D A; Jenerette, G D

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality. PMID:26556236

  18. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    PubMed Central

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality. PMID:26556236

  19. Soot Surface Oxidation in Laminar Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix I

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Kim, C. H.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2003-01-01

    Soot surface oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round fuel jets burning in coflowing dry air considering acetylene-nitrogen, ethylene, propyiene-nitrogen, propane and acetylene-benzene-nitrogen in the fuel stream. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of major stable gas species (N2, H2O, H2, O2, CO, CO2, CH4, C2H2, C2H6, C3H6, C3H8, and C6H6) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by deconvoluted Li/LiOH atomic absorption and flow velocities by laser velocimetry. For present test conditions, it was found that soot surface oxidation rates were not affected by fuel type, that direct rates of soot surface oxidation by O2 estimated from Nagle and Strickland-Constable (1962) were small compared to observed soot surface oxidation rates because soot surface oxidation was completed near the flame sheet where O2 concentrations were less than 3% by volume, and that soot surface oxidation rates were described by the OH soot surface oxidation mechanism with a collision efficiency of 0.14 and an uncertainty (95% confidence) of +/- 0.04 when allowing for direct soot surface oxidation by O2, which is in reasonably good agreement with earlier observations of soot surface oxidation rates in both premixed and diffusion flames at atmospheric pressure.

  20. Processing of uranium oxide powders in a fluidized-bed reactor. I. Experimental

    NASA Astrophysics Data System (ADS)

    Cho, W. D.; Han, Man-Hee; Bronson, Mark C.; Zundelevich, Yury

    2002-10-01

    The oxidation of UN powders was carried out in a spout-type fluidized-bed reactor in gas mixtures of oxygen and argon, and over the temperature range of 200-500 °C. The rate of the conversion from UN to U 3O 8 powders was measured using gas chromatography and found to be dependent on temperature, partial pressure of oxygen and gas flowrate. The solid reactants and products were analyzed using SEM and XRD. Based on the experimental results, the conversion process was explained by the crackling core model.

  1. Temperature dependence of catalytic cyclohexane partial oxidation in a polytetrafluoroethylene reactor

    NASA Astrophysics Data System (ADS)

    Lončarević, D.; Krstić, J.; Banković, P.; Anić, S.; Čupić, Ž.

    2007-09-01

    Polymer-supported Co(II) catalyst was prepared and its activity and selectivity in the partial oxidation of cyclohexane was determined at several temperatures in a polytetrafluoroethylene reactor (PTFE). The catalyst was characterized by means of SEM-EDX, FTIR, diffuse reflectance UV-Vis, N2 sorption, and mecury porosimetry. Activation energies were determined under steady state conditions for the net production of cyclohexanone and cyclohexanol and for cyclohexane and oxygen net consumption. Some activation energies were lower than the ones reported for the uncatalyzed process, indicating that the catalyst played an important role in the initiation of the free-radical reaction.

  2. Catalytic oxidation of trace levels of methane in oxygen in a tubular reactor

    NASA Technical Reports Server (NTRS)

    Warshay, M.; Caenepeel, C. L.

    1974-01-01

    An experimental investigation of catalytic oxidation of trace levels of methane in oxygen was conducted in a tubular reactor. Two noble metal solid catalysts were explored: a 1-percent platinum on gamma alumina and a 0.5-percent rhodium on gamma alumina. For each catalyst the activity was determined as a function of temperature, pressure, space velocity, and methane concentration. The rhodium catalyst was considerably more active than the platinum catalyst. For each catalyst mass transfer had a pronounced effect upon activity at low space velocity.

  3. Isothermal and cyclic oxidation of an air plasma-sprayed thermal barrier coating system

    SciTech Connect

    Haynes, J.A.; Ferber, M.K.; Porter, W.D.; Rigney, E.D.

    1996-08-01

    Thermogravimetric methods for evaluating bond coat oxidation in plasma-sprayed thermal barrier coating (TBC) systems were assessed by high-temperature testing of TBC systems with air plasma-sprayed (APS) Ni-22Cr-10Al-1Y bond coatings and yttria-stabilized zirconia top coatings. High-mass thermogravimetric analysis (at 1150{sup degrees}C) was used to measure bond coat oxidation kinetics. Furnace cycling was used to evaluate APS TBC durability. This paper describes the experimental methods and relative oxidation kinetics of the various specimen types. Characterization of the APS TBCs and their reaction products is discussed.

  4. Air-Driven Potassium Iodide-Mediated Oxidative Photocyclization of Stilbene Derivatives.

    PubMed

    Matsushima, Tomoya; Kobayashi, Sayaka; Watanabe, Soichiro

    2016-09-01

    A new method has been developed for the potassium iodide-mediated oxidative photocyclization of stilbene derivatives. Compared with conventional iodine-mediated oxidative photocyclization reactions, this new method requires shorter reaction times and affords cyclized products in yields of 45-97%. This reaction proceeds with a catalytic amount of potassium iodide and works in an air-driven manner without the addition of an external scavenger. The radical-mediated oxidative photocyclization of stilbene derivatives using TEMPO was also investigated. PMID:27508401

  5. Solid oxide fuel cell power plant having a fixed contact oxidation catalyzed section of a multi-section cathode air heat exchanger

    DOEpatents

    Saito, Kazuo; Lin, Yao

    2015-02-17

    The multi-section cathode air heat exchanger (102) includes at least a first heat exchanger section (104), and a fixed contact oxidation catalyzed section (126) secured adjacent each other in a stack association. Cool cathode inlet air flows through cool air channels (110) of the at least first (104) and oxidation catalyzed sections (126). Hot anode exhaust flows through hot air channels (124) of the oxidation catalyzed section (126) and is combusted therein. The combusted anode exhaust then flows through hot air channels (112) of the first section (104) of the cathode air heat exchanger (102). The cool and hot air channels (110, 112) are secured in direct heat exchange relationship with each other so that temperatures of the heat exchanger (102) do not exceed 800.degree. C. to minimize requirements for using expensive, high-temperature alloys.

  6. REACTOR

    DOEpatents

    Szilard, L.

    1963-09-10

    A breeder reactor is described, including a mass of fissionable material that is less than critical with respect to unmoderated neutrons and greater than critical with respect to neutrons of average energies substantially greater than thermal, a coolant selected from sodium or sodium--potassium alloys, a control liquid selected from lead or lead--bismuth alloys, and means for varying the quantity of control liquid in the reactor. (AEC)

  7. REACTOR

    DOEpatents

    Christy, R.F.

    1961-07-25

    A means is described for co-relating the essential physical requirements of a fission chain reaction in order that practical, compact, and easily controllable reactors can be built. These objects are obtained by employing a composition of fissionsble isotope and moderator in fluid form in which the amount of fissionsble isotcpe present governs the reaction. The size of the reactor is no longer a critical factor, the new criterion being the concentration of the fissionable isotope.

  8. AIR PARTICULATE POLLUTION EXPOSURE INDUCES SYSTEMIC OXIDATIVE STRESS IN HEALTHY MICE

    EPA Science Inventory

    Air particulate pollution exposure induces systemic oxidative stress in healthy mice

    Elizabeth S Roberts1 and Kevin L Dreher2. 1 College or Veterinary Medicine, NC State University, Raleigh, NC , 2US Environmental Protection Agency, NHEERL, RTP, NC

    Epidemiological s...

  9. IN VITRO CARDIOTOXICITY OF AIR POLLUTION PARTICLES: ROLE OF BIOAVAILABLE CONSTITUENTS, OXIDATIVE STRESS AND TYROSINE PHOSPHORYLATION

    EPA Science Inventory

    IN VITRO CARDIOTOXICITY OF AIR POLLUTION PARTICLES: ROLE OF BIOAVAILABLE CONSTITUENTS, OXIDATIVE STRESS AND TYROSINE PHOSPHORYLATION.

    T. L. Knuckles1 R. Jaskot2, J. Richards2, and K.Dreher2.
    1Department of Molecular and Biomedical Sciences, College of Veterinary Medicin...

  10. PHOTOCHEMICAL OXIDANT AIR POLLUTION EFFECTS ON A MIXED CONIFER FOREST ECOSYSTEM

    EPA Science Inventory

    EPA contract 68-03-2442 provided support for three years of the studies to determine the chronic effects of photochemical oxidant air pollutants on a western mixed conifer forest ecosystem. This report deals with the year 1976-77 and is the final publication on EPA contract 68-03...

  11. COST ANALYSIS OF ACTIVATED CARBON VERSUS PHOTOCATALYTIC OXIDATION FOR REMOVING ORGANIC COMPOUNDS FROM INDOOR AIR

    EPA Science Inventory

    A cost comparison has been conducted of 1 m3/s indoor air cleaners using granular activated carbon (GAC) vs. photocatalytic oxidation (PCO) for treating a steady-state inlet volatile organic compound (VOC) concentration of 0.3 mg/m3. The commercial GAC unit was costed assuming t...

  12. Air Quality Criteria for Ozone and Related Photochemical Oxidants (First External Review Draft)

    EPA Science Inventory

    This first external review draft of the Air Quality Criteria for Ozone and Related Photochemical Oxidants (Ozone Criteria Document) is being released in January 2005 for public comment and for review by EPA's Clean A...

  13. Spectroscopic Studies On Powdered CeNi5 Oxidized In Air

    SciTech Connect

    Coldea, M.; Pacurariu, R.; Pascut, L. G.; Rednic, V.; Neumann, M.

    2007-04-23

    The synthesis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) of Ni isolated single domain particles, obtained from powdered CeNi5 oxidized in air at different temperatures up to 800 deg. C, are reported.

  14. LEAF PHOTOSYNTHETIC AND WATER RELATIONS RESPONSES FOR "VALENCIA" ORANGE TREES EXPOSED TO OXIDANT AIR POLLUTION

    EPA Science Inventory

    Leaf responses were measured to test a hypothesis that reduced photosynthetic capacity and/or altered water relations were associated with reductions in yield for "Valencia" orange trees exposed to ambient oxidant air pollution. xposures were continuous for four years to three le...

  15. OXIDANT AIR POLLUTANT EFFECTS ON A WESTERN CONIFEROUS FOREST ECOSYSTEM: TASK A, PLANNING CONFERENCE

    EPA Science Inventory

    This is a report on a planning conference to develop a protocol for a study on the impact of oxidant air pollution from an urban area on a forest ecosystem and recreational area. The conference was held July 21-23, 1971 at the Arrowhead Conference Center in California to discuss ...

  16. THE EFFECTS OF OXIDANT AIR POLLUTANTS ON SOYBEANS, SNAP BEANS AND POTATOES

    EPA Science Inventory

    During the past 5 years the impact of photochemical oxidants on soybeans and snap beans in Maryland and on potatoes in Virginia and Delaware was assessed with open-top chambers. The mean yields of four selected soybean varieties grown in open-top chambers with carbon-filtered air...

  17. OXIDATION OF CYCLOHEXANE WITH AIR CATALYZED BY A STERICALLY HINDERED IRON (II) COMPLEX

    EPA Science Inventory

    Oxidation of Cyclohexane with Air Catalyzed by a Sterically Hindered Iron(II) Complex.


    Thomas M. Becker, Michael A. Gonzalez*

    United States Environmental Protection Agency; National Risk Management Research Laboratory; Sustainable Technology Division; Clean Pr...

  18. Effects of air oxidation on the dissolution rate of LWR spent fuel

    SciTech Connect

    Gray, W.J.; Thomas, L.E.; Einziger, R.E.

    1993-12-31

    Dissolution rates for air-oxidized spent fuel were measured in flowthrough tests where U concentrations were kept well below the solubility limit. Results from two types of specimens, separated grains and coarse particles, both in oxidized (U{sub 4}O{sub 9+x}) and unoxidized (UO{sub 2}) conditions indicated only minor effects of oxidation on the surface-area-normalized rates. Similar results were obtained for unirradiated specimens in three different oxidation states (UO{sub 2}, U{sub 3}O{sub 7}, and U{sub 3}O{sub 8}). These observations have important practical implications for disposal of spent fuel in a geologic repository as well as implications regarding the oxidative dissolution mechanism of UO{sub 2} fuel.

  19. CFD Modeling of Sodium-Oxide Deposition in Sodium-Cooled Fast Reactor Compact Heat Exchangers

    SciTech Connect

    Tatli, Emre; Ferroni, Paolo; Mazzoccoli, Jason

    2015-09-02

    The possible use of compact heat exchangers (HXs) in sodium-cooled fast reactors (SFR) employing a Brayton cycle is promising due to their high power density and resulting small volume in comparison with conventional shell-and-tube HXs. However, the small diameter of their channels makes them more susceptible to plugging due to Na2O deposition during accident conditions. Although cold traps are designed to reduce oxygen impurity levels in the sodium coolant, their failure, in conjunction with accidental air ingress into the sodium boundary, could result in coolant oxygen levels that are above the saturation limit in the cooler parts of the HX channels. This can result in Na2O crystallization and the formation of solid deposits on cooled channel surfaces, limiting or even blocking coolant flow. The development of analysis tools capable of modeling the formation of these deposits in the presence of sodium flow will allow designers of SFRs to properly size the HX channels so that, in the scenario mentioned above, the reactor operator has sufficient time to detect and react to the affected HX. Until now, analytical methodologies to predict the formation of these deposits have been developed, but never implemented in a high-fidelity computational tool suited to modern reactor design techniques. This paper summarizes the challenges and the current status in the development of a Computational Fluid Dynamics (CFD) methodology to predict deposit formation, with particular emphasis on sensitivity studies on some parameters affecting deposition.

  20. OXIDANT AIR POLLUTION IN REMOTE FORESTED AREAS OF SOUTHWESTERN VIRGINIA. OXIDANT EFFECT ON EASTERN WHITE PINE

    EPA Science Inventory

    Total oxidants and associated oxidant injury to white pine were determined at three rural sites in Virginia: (1) Salt Pond Mountain, Giles County; (2) Rocky Knob Mountain, Floyd County; and, (3) Shenandoah Valley, Rockingham County, at 945 m, 945 m, and 426 m elevation, respectiv...

  1. Microalgae cultivation in air-lift reactors: modeling biomass yield and growth rate as a function of mixing frequency.

    PubMed

    Barbosa, Maria J; Janssen, Marcel; Ham, Nienke; Tramper, Johannes; Wijffels, René H

    2003-04-20

    The slow development of microalgal biotechnology stems from the failure in the design of large-scale photobioreactors where light energy is efficiently utilized. Due to the light gradient inside the reactor and depending on the mixing properties, algae are subjected to certain light/dark cycles where the light period is characterized by a light gradient. These light/dark cycles will determine productivity and biomass yield on light energy. Air-lift reactors can be used for microalgae cultivation and medium-frequency light/dark cycles will be found in these systems. Light/dark cycles are associated with two basic parameters: first, the light fraction, i.e., the ratio between the light period and the cycle time and second, the frequency of the light/dark cycle. In the present work, light/dark cycles found in air-lift reactors were simulated taking into account the light gradient during the light period. The effect of medium-frequency cycle time (10-100 s) and light fraction (0.1-1) on growth rate and biomass yield on light energy of the microalgae Dunaliella tertiolecta was studied. The biomass yield and growth rates were mainly affected by the light fraction, while cycle time had little influence. Response surface methodology was used and a statistical model describing the effect of light fraction and cycle time on growth rate and biomass yield on light energy was developed. The use of the model as a reactor design criterion is discussed. PMID:12584758

  2. Startup of reactors for anoxic ammonium oxidation: experiences from the first full-scale anammox reactor in Rotterdam.

    PubMed

    van der Star, Wouter R L; Abma, Wiebe R; Blommers, Dennis; Mulder, Jan-Willem; Tokutomi, Takaaki; Strous, Marc; Picioreanu, Cristian; van Loosdrecht, Mark C M

    2007-10-01

    The first full-scale anammox reactor in the world was started in Rotterdam (NL). The reactor was scaled-up directly from laboratory-scale to full-scale and treats up to 750 kg-N/d. In the initial phase of the startup, anammox conversions could not be identified by traditional methods, but quantitative PCR proved to be a reliable indicator for growth of the anammox population, indicating an anammox doubling time of 10-12 days. The experience gained during this first startup in combination with the availability of seed sludge from this reactor, will lead to a faster startup of anammox reactors in the future. The anammox reactor type employed in Rotterdam was compared to other reactor types for the anammox process. Reactors with a high specific surface area like the granular sludge reactor employed in Rotterdam provide the highest volumetric loading rates. Mass transfer of nitrite into the biofilm is limiting the conversion of those reactor types that have a lower specific surface area. Now the first full-scale commercial anammox reactor is in operation, a consistent and descriptive nomenclature is suggested for reactors in which the anammox process is employed. PMID:17583763

  3. Treatment of high-strength industrial wastewater by wet air oxidation--A case study

    SciTech Connect

    Lin, S.H.; Ho, S.J.

    1997-12-31

    Treatment of high concentration chemical wastewater obtained from a petrochemical company by wet air oxidation (WAO) is studied. Experiments were conducted to investigate the effects of the mixer speed, operating pressure, initial pH of wastewater and temperature on the pollutant (chemical oxygen demand or COD) removal. Both air and oxygen were tested to determine their respective effect on the COD removal. Results showed that over 50% of COD removal can be easily realized in an hour of WAO treatment. Also considered in the present study was the catalytic WAO treatment of the high concentration wastewater. Copper sulfate (CuSO{sub 4}), cobalt oxide (Co{sub 2}O{sub 3}) and zinc oxide (ZnO) were employed as the catalysts. The COD removal efficiency of the catalytic WAO process was found to vary significantly with the catalyst utilized with CuSO{sub 4} being the most effective.

  4. Impact of Air Pollutants on Oxidative Stress in Common Autophagy-Mediated Aging Diseases

    PubMed Central

    Numan, Mohamed Saber; Brown, Jacques P.; Michou, Laëtitia

    2015-01-01

    Atmospheric pollution-induced cellular oxidative stress is probably one of the pathogenic mechanisms involved in most of the common autophagy-mediated aging diseases, including neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer’s, disease, as well as Paget’s disease of bone with or without frontotemporal dementia and inclusion body myopathy. Oxidative stress has serious damaging effects on the cellular contents: DNA, RNA, cellular proteins, and cellular organelles. Autophagy has a pivotal role in recycling these damaged non-functional organelles and misfolded or unfolded proteins. In this paper, we highlight, through a narrative review of the literature, that when autophagy processes are impaired during aging, in presence of cumulative air pollution-induced cellular oxidative stress and due to a direct effect on air pollutant, autophagy-mediated aging diseases may occur. PMID:25690002

  5. INVESTIGATION OF A NOVEL AIR BRAZING COMPOSITION FOR HIGH-TEMPERATURE, OXIDATION-RESISTANT CERAMIC JOINING

    SciTech Connect

    Weil, K. Scott; Hardy, John S.; Darsell, Jens T.

    2004-01-30

    One of the challenges in developing a useful ceramic joining technique is in producing a joint that offers good strength under high temperature and highly oxidizing operating conditions. Unfortunately many of the commercially available active metal ceramic brazing alloys exhibit oxidation behaviors which are unacceptable for use in a high temperature application. We have developed a new approach to ceramic brazing, referred to as air brazing, that employs an oxide wetting agent dissolved in a molten noble metal solvent, in this case CuO in Ag, such that acceptable wetting behavior occurs on a number of ceramic substrates. In an effort to explore how to increase the operating temperature of this type of braze, we have investigated the effect of ternary palladium additions on the wetting characteristics of our standard Ag-CuO air braze composition

  6. Survey of Worldwide Light Water Reactor Experience with Mixed Uranium-Plutonium Oxide Fuel

    SciTech Connect

    Cowell, B.S.; Fisher, S.E.

    1999-02-01

    The US and the Former Soviet Union (FSU) have recently declared quantities of weapons materials, including weapons-grade (WG) plutonium, excess to strategic requirements. One of the leading candidates for the disposition of excess WG plutonium is irradiation in light water reactors (LWRs) as mixed uranium-plutonium oxide (MOX) fuel. A description of the MOX fuel fabrication techniques in worldwide use is presented. A comprehensive examination of the domestic MOX experience in US reactors obtained during the 1960s, 1970s, and early 1980s is also presented. This experience is described by manufacturer and is also categorized by the reactor facility that irradiated the MOX fuel. A limited summary of the international experience with MOX fuels is also presented. A review of MOX fuel and its performance is conducted in view of the special considerations associated with the disposition of WG plutonium. Based on the available information, it appears that adoption of foreign commercial MOX technology from one of the successful MOX fuel vendors will minimize the technical risks to the overall mission. The conclusion is made that the existing MOX fuel experience base suggests that disposition of excess weapons plutonium through irradiation in LWRs is a technically attractive option.

  7. Nitric oxide reduction in BioDeNOx reactors: kinetics and mechanism.

    PubMed

    van der Maas, Peter; Manconi, Isabella; Klapwijk, Bram; Lens, Piet

    2008-08-15

    Biological reduction of nitric oxide (NO) to di-nitrogen (N(2)) gas in aqueous Fe(II)EDTA(2-) solutions is a key reaction in BioDeNOx, a novel process for NOx removal from flue gases. The mechanism and kinetics of the first step of NO reduction, that is, the conversion of NO to N(2)O, was determined in batch experiments using various types of inocula. Experiments were performed in Fe(II)EDTA(2-) medium (5-25 mM) under BioDeNOx reactor conditions (55 degrees C, pH 7.2 +/- 0.2) with ethanol as external electron donor. BioDeNOx reactor mixed liquor gave the highest NO reduction rates (+/-0.34 nmol s(-1) mg(prot)(-1)) with an estimated K(m) value for NO lower than 10 nM. The specific NO (to N(2)O) reduction rate depended on the NO (aq) and Fe(II)EDTA(2-) concentration as well as the temperature. The experimental results, complemented with kinetic and thermodynamic considerations, show that Fe(II)EDTA(2-), and not ethanol, is the primary electron donor for NO reduction, that is, the BioDeNOx reactor medium (the redox system Fe(II)EDTA(2-)/Fe(III)EDTA(-)) interferes with the NO reduction electron transfer chain and thus enhances the NO denitrification rate. PMID:18553393

  8. Nitrous oxide production from sequencing batch reactor sludge under nitrifying conditions: effect of nitrite concentrations.

    PubMed

    Gong, Youkui; Wang, Shuying; Wang, Sai; Peng, Yongzhen

    2012-01-01

    Nitrous oxide (N2O), a greenhouse gas which contributes to the destruction of the stratospheric ozone layer, can be emitted from nitrifying processes during wastewater treatment. The pathway of N2O production was studied using a lab-scale nitrifying reactor. Allylthiourea was used to inhibit NH4+ oxidation and provide information on processes that happen under nitrifying condition. Our study confirmed that besides heterotrophic bacteria, ammonium-oxidizing bacteria could perform denitrification processes, during which NO2- was the electron acceptor and NH4+ was the electron donor, with N2 and N2O as final products. The relative contribution of the heterotrophic denitrification process to total N2O emissions varied from 46.1% to 60.4% depending on NO2(-)-N addition. Correspondingly, 21.8% to 51.5% of total N2O emissions can be attributed to nitrifier denitrification. Little N2O is emitted during the NO2- oxidation process. PMID:22629611

  9. Diversity Profile of Microbes Associated with Anaerobic Sulfur Oxidation in an Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Sewage

    PubMed Central

    Aida, Azrina A.; Kuroda, Kyohei; Yamamoto, Masamitsu; Nakamura, Akinobu; Hatamoto, Masashi; Yamaguchi, Takashi

    2015-01-01

    We herein analyzed the diversity of microbes involved in anaerobic sulfur oxidation in an upflow anaerobic sludge blanket (UASB) reactor used for treating municipal sewage under low-temperature conditions. Anaerobic sulfur oxidation occurred in the absence of oxygen, with nitrite and nitrate as electron acceptors; however, reactor performance parameters demonstrated that anaerobic conditions were maintained. In order to gain insights into the underlying basis of anaerobic sulfur oxidation, the microbial diversity that exists in the UASB sludge was analyzed comprehensively to determine their identities and contribution to sulfur oxidation. Sludge samples were collected from the UASB reactor over a period of 2 years and used for bacterial 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) and next-generation sequencing analyses. T-RFLP and sequencing results both showed that microbial community patterns changed markedly from day 537 onwards. Bacteria belonging to the genus Desulforhabdus within the phylum Proteobacteria and uncultured bacteria within the phylum Fusobacteria were the main groups observed during the period of anaerobic sulfur oxidation. Their abundance correlated with temperature, suggesting that these bacterial groups played roles in anaerobic sulfur oxidation in UASB reactors. PMID:25817585

  10. Effect of inorganic carbon on anaerobic ammonium oxidation enriched in sequencing batch reactor.

    PubMed

    Liao, Dexiang; Li, Xiaoming; Yang, Qi; Zeng, Guangming; Guo, Liang; Yue, Xiu

    2008-01-01

    The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon (sodium bicarbonate) on anaerobic ammonium oxidation. The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor (SBR) and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR. Research results, especially the biomass, showed first signs of anammox activity after 54 d cultivation with synthetic wastewater, when the pH was controlled between 7.5 and 8.3, the temperature was 35 degrees C. The anammox activity increased as the influent bicarbonate concentration increased from 1.0 to 1.5 g/L, and then, was inhibited as the bicarbonate concentration approached 2.0 g/L. However, the activity could be restored by the reduction of bicarbonate concentration to 1.0 g/L, as shown by rapid conversion of ammonium, and nitrite and nitrate production with normal stoichiometry. The optimization of the bicarbonate concentration in the reactor could increase the anammox rate up to 66.4 mgN/(L x d). PMID:18817072

  11. Continuous Polyol Synthesis of Metal and Metal Oxide Nanoparticles Using a Segmented Flow Tubular Reactor (SFTR).

    PubMed

    Testino, Andrea; Pilger, Frank; Lucchini, Mattia Alberto; Quinsaat, Jose Enrico Q; Stähli, Christoph; Bowen, Paul

    2015-01-01

    Over the last years a new type of tubular plug flow reactor, the segmented flow tubular reactor (SFTR), has proven its versatility and robustness through the water-based synthesis of precipitates as varied as CaCO3, BaTiO3, Mn(1-x)NixC2O4·2H2O, YBa oxalates, copper oxalate, ZnS, ZnO, iron oxides, and TiO2 produced with a high powder quality (phase composition, particle size, and shape) and high reproducibility. The SFTR has been developed to overcome the classical problems of powder production scale-up from batch processes, which are mainly linked with mass and heat transfer. Recently, the SFTR concept has been further developed and applied for the synthesis of metals, metal oxides, and salts in form of nano- or micro-particles in organic solvents. This has been done by increasing the working temperature and modifying the particle carrying solvent. In this paper we summarize the experimental results for four materials prepared according to the polyol synthesis route combined with the SFTR. CeO2, Ni, Ag, and Ca3(PO4)2 nanoparticles (NPs) can be obtained with a production rate of about 1-10 g per h. The production was carried out for several hours with constant product quality. These findings further corroborate the reliability and versatility of the SFTR for high throughput powder production. PMID:26060919

  12. Modeling of thermo-mechanical and irradiation behavior of mixed oxide fuel for sodium fast reactors

    NASA Astrophysics Data System (ADS)

    Karahan, Aydın; Buongiorno, Jacopo

    2010-01-01

    An engineering code to model the irradiation behavior of UO2-PuO2 mixed oxide fuel pins in sodium-cooled fast reactors was developed. The code was named fuel engineering and structural analysis tool (FEAST-OXIDE). FEAST-OXIDE has several modules working in coupled form with an explicit numerical algorithm. These modules describe: (1) fission gas release and swelling, (2) fuel chemistry and restructuring, (3) temperature distribution, (4) fuel-clad chemical interaction and (5) fuel-clad mechanical analysis. Given the fuel pin geometry, composition and irradiation history, FEAST-OXIDE can analyze fuel and cladding thermo-mechanical behavior at both steady-state and design-basis transient scenarios. The code was written in FORTRAN-90 program language. The mechanical analysis module implements the LIFE algorithm. Fission gas release and swelling behavior is described by the OGRES and NEFIG models. However, the original OGRES model has been extended to include the effects of joint oxide gain (JOG) formation on fission gas release and swelling. A detailed fuel chemistry model has been included to describe the cesium radial migration and JOG formation, oxygen and plutonium radial distribution and the axial migration of cesium. The fuel restructuring model includes the effects of as-fabricated porosity migration, irradiation-induced fuel densification, grain growth, hot pressing and fuel cracking and relocation. Finally, a kinetics model is included to predict the clad wastage formation. FEAST-OXIDE predictions have been compared to the available FFTF, EBR-II and JOYO databases, as well as the LIFE-4 code predictions. The agreement was found to be satisfactory for steady-state and slow-ramp over-power accidents.

  13. Applicability of fluidized bed reactor in recalcitrant compound degradation through advanced oxidation processes: a review.

    PubMed

    Tisa, Farhana; Abdul Raman, Abdul Aziz; Wan Daud, Wan Mohd Ashri

    2014-12-15

    Treatment of industrial waste water (e.g. textile waste water, phenol waste water, pharmaceutical etc) faces limitation in conventional treatment procedures. Advanced oxidation processes (AOPs) do not suffer from the limits of conventional treatment processes and consequently degrade toxic pollutants more efficiently. Complexity is faced in eradicating the restrictions of AOPs such as sludge formation, toxic intermediates formation and high requirement for oxidants. Increased mass-transfer in AOPs is an alternate solution to this problem. AOPs combined with Fluidized bed reactor (FBR) can be a potential choice compared to fixed bed or moving bed reactor, as AOP catalysts life-span last for only maximum of 5-10 cycles. Hence, FBR-AOPs require lesser operational and maintenance cost by reducing material resources. The time required for AOP can be minimized using FBR and also treatable working volume can be increased. FBR-AOP can process from 1 to 10 L of volume which is 10 times more than simple batch reaction. The mass transfer is higher thus the reaction time is lesser. For having increased mass transfer sludge production can be successfully avoided. The review study suggests that, optimum particle size, catalyst to reactor volume ratio, catalyst diameter and liquid or gas velocity is required for efficient FBR-AOP systems. However, FBR-AOPs are still under lab-scale investigation and for industrial application cost study is needed. Cost of FBR-AOPs highly depends on energy density needed and the mechanism of degradation of the pollutant. The cost of waste water treatment containing azo dyes was found to be US$ 50 to US$ 500 per 1000 gallons where, the cost for treating phenol water was US$ 50 to US$ 800 per 1000 gallons. The analysis for FBR-AOP costs has been found to depend on the targeted pollutant, degradation mechanism (zero order, 1st order and 2nd order) and energy consumptions by the AOPs. PMID:25190594

  14. Flow reactor studies of non-equilibrium plasma-assisted oxidation of n-alkanes.

    PubMed

    Tsolas, Nicholas; Lee, Jong Guen; Yetter, Richard A

    2015-08-13

    The oxidation of n-alkanes (C1-C7) has been studied with and without the effects of a nanosecond, non-equilibrium plasma discharge at 1 atm pressure from 420 to 1250 K. Experiments have been performed under nearly isothermal conditions in a flow reactor, where reactive mixtures are diluted in Ar to minimize temperature changes from chemical reactions. Sample extraction performed at the exit of the reactor captures product and intermediate species and stores them in a multi-position valve for subsequent identification and quantification using gas chromatography. By fixing the flow rate in the reactor and varying the temperature, reactivity maps for the oxidation of fuels are achieved. Considering all the fuels studied, fuel consumption under the effects of the plasma is shown to have been enhanced significantly, particularly for the low-temperature regime (T<800 K). In fact, multiple transitions in the rates of fuel consumption are observed depending on fuel with the emergence of a negative-temperature-coefficient regime. For all fuels, the temperature for the transition into the high-temperature chemistry is lowered as a consequence of the plasma being able to increase the rate of fuel consumption. Using a phenomenological interpretation of the intermediate species formed, it can be shown that the active particles produced from the plasma enhance alkyl radical formation at all temperatures and enable low-temperature chain branching for fuels C3 and greater. The significance of this result demonstrates that the plasma provides an opportunity for low-temperature chain branching to occur at reduced pressures, which is typically observed at elevated pressures in thermal induced systems. PMID:26170423

  15. Synthesis and characterization of carbon black/manganese oxide air cathodes for zinc-air batteries: Effects of the crystalline structure of manganese oxides

    NASA Astrophysics Data System (ADS)

    Li, Po-Chieh; Hu, Chi-Chang; Noda, Hiroyuki; Habazaki, Hiroki

    2015-12-01

    Manganese oxides (MnOx) in α-, β-, γ-, δ-MnO2 phases, Mn3O4, Mn2O3, and MnOOH are synthesized for systematically comparing their electrocatalytic activity of the oxygen reduction reaction (ORR) in the Zn-air battery application. The optimal MnOx/XC-72 mass ratio for the ORR is equal to 1 and the oxide crystalline structure effect on the ORR is compared. The order of composites with respect to decreasing the ORR activity is: α-MnO2/XC-72 > γ-MnO2/XC-72 > β-MnO2/XC-72 > δ-MnO2/XC-72 > Mn2O3/XC-72 > Mn3O4/XC-72 > MnOOH/XC-72. The textural properties of MnOx are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption isotherms with Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Electrochemical studies include linear sweep voltammetry (LSV), rotating ring-disk electrode (RRDE) voltammetry, and the full-cell discharge test. The discharge peak power density of Zn-air batteries varies from 61.5 mW cm-2 (α-MnO2/XC-72) to 47.1 mW cm-2 (Mn3O4/XC-72). The maximum peak power density is 102 mW cm-2 for the Zn-air battery with an air cathode containing α-MnO2/XC-72 under an oxygen atmosphere when the carbon paper is 10AA. The specific capacity of all full-cell tests is higher than 750 mAh g-1 at all discharge current densities.

  16. Soot Oxidation in Laminar Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix D

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Faeth, G. M.

    2000-01-01

    Soot oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round jets burning in coflowing air considering acetylene, ethylene, proplyene and propane as fuels. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation mainly occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of stable major gas species (N2, H2O, H2, 02, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H6, and C3H8) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by the deconvoluted Li/LiOH atomic absorption technique and flow velocities by laser velocimetry. It was found that soot surface oxidation rates are not particularly affected by fuel type for laminar diffusion flames and are described reasonably well by the OH surface oxidation mechanism with a collision efficiency of 0.10, (standard deviation of 0.07) with no significant effect of fuel type in this behavior; these findings are in good agreement with the classical laminar premixed flame measurements of Neoh et al. Finally, direct rates of surface oxidation by O2 were small compared to OH oxidation for present conditions, based on estimated O2 oxidation rates due to Nagle and Strickland-Constable, because soot oxidation was completed near the flame sheet where O2 concentrations were less than 1.2% by volume.

  17. Soot Oxidation in Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix K

    NASA Technical Reports Server (NTRS)

    Xu, F.; El-Leathy, A. M.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    Soot oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round jets burning in coflowing air considering acetylene, ethylene, propylene and propane as fuels. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation mainly occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of stable major gas species (N2, H2O, H2, O2, CO, CO2, CH4, C2H2,C2H4, C2H6, C3H6, and C3H8) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by the deconvoluted Li/LiOH atomic absorption technique and flow velocities by laser velocimetry. It was found that soot surface oxidation rates are not particularly affected by fuel type for laminar diffusion flames and are described reasonably well by the OH surface oxidation mechanism with a collision efficiency of 0.10, (standard deviation of 0.07) with no significant effect of fuel type in this behavior; these findings are in good agreement with the classical laminar premixed flame measurements of Neoh et al. Finally, direct rates of surface oxidation by O2 were small compared to OH oxidation for present conditions, based on estimated O2 oxidation rates due to Nagle and Strickland-Constable (1962), because soot oxidation was completed near the flame sheet where O2 concentrations were less than 1.2% by volume.

  18. Development of a Prototype Algal Reactor for Removing CO2 from Cabin Air

    NASA Technical Reports Server (NTRS)

    Patel, Vrajen; Monje, Oscar

    2013-01-01

    Controlling carbon dioxide in spacecraft cabin air may be accomplished using algal photobioreactors (PBRs). The purpose of this project was to evaluate the use of a commercial microcontroller, the Arduino Mega 2560, for measuring key photioreactor variables: dissolved oxygen, pH, temperature, light, and carbon dioxide. The Arduino platform is an opensource physical computing platform composed of a compact microcontroller board and a C++/C computer language (Arduino 1.0.5). The functionality of the Arduino platform can be expanded by the use of numerous add-ons or 'shields'. The Arduino Mega 2560 was equipped with the following shields: datalogger, BNC shield for reading pH sensor, a Mega Moto shield for controlling CO2 addition, as well as multiple sensors. The dissolved oxygen (DO) probe was calibrated using a nitrogen bubbling technique and the pH probe was calibrated via an Omega pH simulator. The PBR was constructed using a 2 L beaker, a 66 L box for addition of CO2, a micro porous membrane, a diaphragm pump, four 25 watt light bulbs, a MasterFiex speed controller, and a fan. The algae (wild type Synechocystis PCC6803) was grown in an aerated flask until the algae was dense enough to used in the main reactor. After the algae was grown, it was transferred to the 2 L beaker where CO2 consumption and O2 production was measured using the microcontroller sensor suite. The data was recorded via the datalogger and transferred to a computer for analysis.

  19. Oxidation kinetics of some nickel-based superalloy foils and electronic resistance of the oxide scale formed in air. Part 1

    SciTech Connect

    England, D.M.; Virkar, A.V.

    1999-09-01

    Haynes 230, Inconel 625, Inconel 718, and Hastelloy X foil specimens were oxidized in air for several thousand hours in the temperature range of 800--1,100 C. The oxidation kinetics of alloys studied obeyed the parabolic rate law. Haynes 230 exhibited the slowest oxidation kinetics of the alloys studied. X-ray diffraction, scanning electron microscopy, and electron probe microanalysis (EPMA) were the principal characterization tools employed. Chromium oxide, Cr{sub 2}O{sub 3}, was the predominant oxide phase in the oxide scale of all alloys studied. Manganese chromate was also detected in the oxide scales of Haynes 230, Hastelloy X, and Inconel 625. EPMA showed that the concentration of Mn in the oxide scale was much higher than in the alloy, indicating selective oxidation of Mn. The electronic resistance of the oxide scale was measured in air at temperatures up to 800 C on samples oxidized in air for up to several thousand hours. The oxide scale on Haynes 230 exhibited the lowest area-specific resistance, consistent with its slower oxidation kinetics.

  20. REACTOR

    DOEpatents

    Roman, W.G.

    1961-06-27

    A pressurized water reactor in which automatic control is achieved by varying the average density of the liquid moderator-cooiant is patented. Density is controlled by the temperature and power level of the reactor ftself. This control can be effected by the use of either plate, pellet, or tubular fuel elements. The fuel elements are disposed between upper and lower coolant plenum chambers and are designed to permit unrestricted coolant flow. The control chamber has an inlet opening communicating with the lower coolant plenum chamber and a restricted vapor vent communicating with the upper coolant plenum chamber. Thus, a variation in temperature of the fuel elements will cause a variation in the average moderator density in the chamber which directly affects the power level of the reactor.

  1. Investigation of low temperature solid oxide fuel cells for air-independent UUV applications

    NASA Astrophysics Data System (ADS)

    Moton, Jennie Mariko

    Unmanned underwater vehicles (UUVs) will benefit greatly from high energy density (> 500 Wh/L) power systems utilizing high-energy-density fuels and air-independent oxidizers. Current battery-based systems have limited energy densities (< 400 Wh/L), which motivate development of alternative power systems such as solid oxide fuel cells (SOFCs). SOFC-based power systems have the potential to achieve the required UUV energy densities, and the current study explores how SOFCs based on gadolinia-doped ceria (GDC) electrolytes with operating temperatures of 650°C and lower may operate in the unique environments of a promising UUV power plant. The plant would contain a H 2O2 decomposition reactor to supply humidified O2 to the SOFC cathode and exothermic aluminum/H2O combustor to provide heated humidified H2 fuel to the anode. To characterize low-temperature SOFC performance with these unique O2 and H2 source, SOFC button cells based on nickel/GDC (Gd0.1Ce0.9O 1.95) anodes, GDC electrolytes, and lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3-δ or LSCF)/GDC cathodes were fabricated and tested for performance and stability with humidity on both the anode and the cathode. Cells were also tested with various reactant concentrations of H2 and O2 to simulate gas depletion down the channel of an SOFC stack. Results showed that anode performance depended primarily on fuel concentration and less on the concentration of the associated increase in product H2O. O 2 depletion with humidified cathode flows also caused significant loss in cell current density at a given voltage. With the humidified flows in either the anode or cathode, stability tests of the button cells at 650 °C showed stable voltage is maintained at low operating current (0.17 A/cm2) at up to 50 % by mole H2O, but at higher current densities (0.34 A/cm2), irreversible voltage degradation occurred at rates of 0.8-3.7 mV/hour depending on exposure time. From these button cell results, estimated average

  2. Model-based evaluation of ferrous iron oxidation by acidophilic bacteria in chemostat and biofilm airlift reactors.

    PubMed

    Ebrahimi, Sirous; Faraghi, Neda; Hosseini, Maryam

    2015-10-01

    This article presents a model-based evaluation of ferrous iron oxidation in chemostat and biofilm airlift reactors inoculated with a mixed culture of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans bacteria. The competition between the two types of bacteria in the chemostat and in the biofilm airlift reactors together with the distribution of both bacteria along the biofilm thickness at different time sections has been studied. The bacterial distribution profiles along the biofilm in the airlift reactor at different time scales show that in the beginning A. ferrooxidans bacteria are dominant, but when the reactor operates for a long time the desirable L. ferrooxidans species outcompete A. ferrooxidans as a result of the low Fe(2+) and high Fe(3+) concentrations. The results obtained from the simulation were compared with the experimental data of continuously operated internal loop airlift biofilm reactor. The model results are in good agreement with the experimental results. PMID:26264929

  3. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 2 2010-07-01 2010-07-01 false National primary and secondary ambient... PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS § 50.11 National primary and secondary ambient air... national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  4. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... SECONDARY AMBIENT AIR QUALITY STANDARDS Pt. 50, App. S Appendix S to Part 50—Interpretation of the Primary... be submitted to EPA's Air Quality System (AQS), or otherwise available to EPA, meeting...

  5. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Zinn, W.H.; Anderson, H.L.

    1958-09-16

    Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

  6. 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.

  7. REACTORS

    DOEpatents

    Spitzer, L. Jr.

    1961-10-01

    Thermonuclear reactors, methods, and apparatus are described for controlling and confining high temperature plasma. Main axial confining coils in combination with helical windings provide a rotational transform that avoids the necessity of a figure-eight shaped reactor tube. The helical windings provide a multipolar helical magnetic field transverse to the axis of the main axial confining coils so as to improve the effectiveness of the confining field by counteracting the tendency of the more central lines of force in the stellarator tube to exchange positions with the magnetic lines of force nearer the walls of the tube. (AEC)

  8. Design considerations and experimental observations for the TAMU air-cooled reactor cavity cooling system for the VHTR

    SciTech Connect

    Sulaiman, S. A. Dominguez-Ontiveros, E. E. Alhashimi, T. Budd, J. L. Matos, M. D. Hassan, Y. A.

    2015-04-29

    The Reactor Cavity Cooling System (RCCS) is a promising passive decay heat removal system for the Very High Temperature Reactor (VHTR) to ensure reliability of the transfer of the core residual and decay heat to the environment under all off-normal circumstances. A small scale experimental test facility was constructed at Texas A and M University (TAMU) to study pertinent multifaceted thermal hydraulic phenomena in the air-cooled reactor cavity cooling system (RCCS) design based on the General Atomics (GA) concept for the Modular High Temperature Gas-Cooled Reactor (MHTGR). The TAMU Air-Cooled Experimental Test Facility is ⅛ scale from the proposed GA-MHTGR design. Groundwork for experimental investigations focusing into the complex turbulence mixing flow behavior inside the upper plenum is currently underway. The following paper illustrates some of the chief design considerations used in construction of the experimental test facility, complete with an outline of the planned instrumentation and data acquisition methods. Computational Fluid Dynamics (CFD) simulations were carried out to furnish some insights on the overall behavior of the air flow in the system. CFD simulations assisted the placement of the flow measurement sensors location. Preliminary experimental observations of experiments at 120oC inlet temperature suggested the presence of flow reversal for cases involving single active riser at both 5 m/s and 2.25 m/s, respectively and four active risers at 2.25 m/s. Flow reversal may lead to thermal stratification inside the upper plenum by means of steady state temperature measurements. A Particle Image Velocimetry (PIV) experiment was carried out to furnish some insight on flow patterns and directions.

  9. Design considerations and experimental observations for the TAMU air-cooled reactor cavity cooling system for the VHTR

    NASA Astrophysics Data System (ADS)

    Sulaiman, S. A.; Dominguez-Ontiveros, E. E.; Alhashimi, T.; Budd, J. L.; Matos, M. D.; Hassan, Y. A.

    2015-04-01

    The Reactor Cavity Cooling System (RCCS) is a promising passive decay heat removal system for the Very High Temperature Reactor (VHTR) to ensure reliability of the transfer of the core residual and decay heat to the environment under all off-normal circumstances. A small scale experimental test facility was constructed at Texas A&M University (TAMU) to study pertinent multifaceted thermal hydraulic phenomena in the air-cooled reactor cavity cooling system (RCCS) design based on the General Atomics (GA) concept for the Modular High Temperature Gas-Cooled Reactor (MHTGR). The TAMU Air-Cooled Experimental Test Facility is ⅛ scale from the proposed GA-MHTGR design. Groundwork for experimental investigations focusing into the complex turbulence mixing flow behavior inside the upper plenum is currently underway. The following paper illustrates some of the chief design considerations used in construction of the experimental test facility, complete with an outline of the planned instrumentation and data acquisition methods. Computational Fluid Dynamics (CFD) simulations were carried out to furnish some insights on the overall behavior of the air flow in the system. CFD simulations assisted the placement of the flow measurement sensors location. Preliminary experimental observations of experiments at 120oC inlet temperature suggested the presence of flow reversal for cases involving single active riser at both 5 m/s and 2.25 m/s, respectively and four active risers at 2.25 m/s. Flow reversal may lead to thermal stratification inside the upper plenum by means of steady state temperature measurements. A Particle Image Velocimetry (PIV) experiment was carried out to furnish some insight on flow patterns and directions.

  10. Lichen communities on conifers in Southern California mountains: an ecological survey relative to oxidant air pollution

    SciTech Connect

    Sigal, L.L.; Nash, T.H. III

    1983-01-01

    In comparison with collections from the early 1900's when oxidant air pollution was essentially absent, 50% fewer lichen species were found on conifers during 3 yr (1976-1979) of collecting and sampling in the mountains of Southern California. Among the five mountain ranges studied, the San Bernardino Mountains, the region with the highest oxidant levels, had lower lichen frequency and cover values. Within the San Bernardino study sites, lichen cover was inversely related to estimated oxidant doses. Furthermore, at sites with high oxidant levels, marked morphological deterioration of the common species Hypogymnia enteromorpha was documented. Transplants of this species from the relatively unpolluted Cuyamaca Rancho State Park into the San Bernardino Mountains exhibited similar deterioration after a year's exposure. 4 figures, 9 tables.

  11. Lichen communities on conifers in Southern California mountains: an ecological survey relative to oxidant air pollution

    SciTech Connect

    Sigal, L.L.; Nash T.H. III

    1983-01-01

    In comparison with collections from the early 1900's when oxidant air pollution was essentially absent, 50% fewer lichen species were found on conifers during 3 yr (1976-1979) of collecting and sampling in the mountains of Southern California. Among the five mountain ranges studied, the San Bernardino Mountains, the region with the highest oxidant levels, had lower lichen frequency and cover values. Within the San Bernardino study sites, lichen cover was inversely related to estimated oxidant doses. Furthermore, at sites with high oxidant levels, marked morphological deterioration of the common species Hypogymnia enteromorpha was documented. Transplants of this species from the relatively unpolluted Cuyamaca Rancho State Park in the San Bernardino Mountains exhibited similar deterioration after a year's exposure.

  12. Air Oxidation Behavior of Two Ti-Base Alloys Synthesized by HIP

    NASA Astrophysics Data System (ADS)

    Liu, S.; Guo, Q. Q.; Liu, L. L.; Xu, L.; Liu, Y. Y.

    2016-04-01

    The oxidation behavior of Ti-5Al-2.5Sn and Ti-6Al-4V produced by hot isostatic pressing (HIP) has been studied at 650-850°C in air for 24 h. The oxidation kinetics of both alloys followed the parabolic law with good approximation, except for Ti-5Al-2.5Sn oxidized at 850°C. Multi-layered scales formed on both alloys at 750°C and 850°C. Ternary additions of Sn and V accounted for the different morphology of the scales formed on these two alloys. In addition, the oxidation behavior of HIP alloys is compared with that of the corresponding cast alloys and the scaling mechanism is discussed.

  13. The Measurement of Fuel-Air Ratio by Analysis for the Oxidized Exhaust Gas

    NASA Technical Reports Server (NTRS)

    Gerrish, Harold C.; Meem, J. Lawrence, Jr.

    1943-01-01

    An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy fuel Specification No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-air ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust gas and the use of graphs for the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-air ratios from 0.047 to 0.124.

  14. The Measurement of Fuel-air Ratio by Analysis of the Oxidized Exhaust Gas

    NASA Technical Reports Server (NTRS)

    Memm, J. Lawrence, Jr.

    1943-01-01

    An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy Fuel Specification, No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-air ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust gas and the use of graphs or the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-air ratios from 0.047 to 0.124

  15. Treatment of aniline by catalytic wet air oxidation: comparative study over CuO/CeO2 and NiO/Al2O3.

    PubMed

    Ersöz, Gülin; Atalay, Süheyda

    2012-12-30

    The treatment of aniline by catalytic wet air oxidation (CWAO) was studied in a bubble reactor. The experiments were performed to investigate the effects of catalyst loading, temperature, reaction time, air flow rate, and pressure on aniline removal. The catalytic effects of the prepared nanostructured catalysts, CuO/CeO(2) (10% wt) and NiO/Al(2)O(3) (10% wt), on the CWAO treatment efficiency were also examined and compared. The prepared catalysts seem to be active having an aniline removal of 45.7% with CuO/CeO(2) and 41.9% with NiO/Al(2)O(3). The amount of N(2) formed was approximately the same for both of the catalysts. PMID:23041516

  16. Prevention of clogging in a biological trickle-bed reactor removing toluene from contaminated air

    SciTech Connect

    Weber, F.J.; Hartmans, S.

    1996-04-05

    Removal of organic compounds like toluene from waste gases with a trickle-bed reactor can result in clogging of the reactor due to the formation of an excessive amount of biomass. The authors therefore limited the amount of nutrients available for growth, to prevent clogging of the reactor. As a consequence of this nutrient limitations a lower removal rate was observed. However, when a fungal culture was used to inoculate the reactor, the toluene removal rate under nutrient limiting conditions was higher. Over a period of 375 days, an average removal rate of 27 g C/(m{sup 3} h) was obtained with the reactor inoculated with the fungal culture. From the carbon balance over the reactor and the nitrogen availability it was concluded that, under these nutrient-limited conditions, large amounts of carbohydrates are probably formed. The authors also studied the application of a NaOH wash to remove excess biomass, as a method to prevent clogging. Under these conditions an average toluene removal rate of 35 g C/(m{sup 3} h) was obtained. After about 50 days there was no net increase in the biomass content of the reactor. The amount of biomass which was formed in the reactor equaled the amount removed by the NaOH wash.

  17. Oxidation of spent fuel in air at 175 degree to 195 degree C

    SciTech Connect

    Einziger, R.E.; Buchanan, H.C.; Thomas, L.E. ); Stout, R.B. )

    1992-04-01

    Oxidation tests in dry air were conducted on four LWR spent fuels at 175{degrees} and 195{degrees}C to determine the effect of the fuel characteristics on the oxidation state likely to exist at the time leaching occurs in a potential repository. Weight changes were measured and samples were examined by XRD, ceramography, TEM, and TGA. Despite local variations in the grain boundary susceptibility to oxidation, all four fuels progressed toward an apparent endpoint at an oxygen-to-metal (O/M) ratio of 2.4. The sole oxidation product was U{sub 4}O{sub 9+x,} a cubic phase structurally related to UO{sub 2} but with a slightly smaller lattice constant. The growth of the U{sub 4}O{sub 9+x} from the grain boundaries into the UO{sub 2} grains followed parabolic kinetics and had an activation energy of 26.6 kcal/mol. Based on the kinetics, the time required at 95{degrees}C to completely oxidize LWR spent fuel to U{sub 4}O{sub 9+x} would be at least 2000 yr. The next oxidation product to form after the U{sub 4}O{sub 9+x} phase may be U{sub 3}O{sub 8,} but no U{sub 3}O{sub 8} or other dilatational oxidation product has been detected in these accelerated tests conducted up to 25,000 h.

  18. Oxidation of spent fuel in air at 175{degree} to 195{degree}C

    SciTech Connect

    Einziger, R.E.; Buchanan, H.C.; Thomas, L.E.; Stout, R.B.

    1992-04-01

    Oxidation tests in dry air were conducted on four LWR spent fuels at 175{degrees} and 195{degrees}C to determine the effect of the fuel characteristics on the oxidation state likely to exist at the time leaching occurs in a potential repository. Weight changes were measured and samples were examined by XRD, ceramography, TEM, and TGA. Despite local variations in the grain boundary susceptibility to oxidation, all four fuels progressed toward an apparent endpoint at an oxygen-to-metal (O/M) ratio of 2.4. The sole oxidation product was U{sub 4}O{sub 9+x,} a cubic phase structurally related to UO{sub 2} but with a slightly smaller lattice constant. The growth of the U{sub 4}O{sub 9+x} from the grain boundaries into the UO{sub 2} grains followed parabolic kinetics and had an activation energy of 26.6 kcal/mol. Based on the kinetics, the time required at 95{degrees}C to completely oxidize LWR spent fuel to U{sub 4}O{sub 9+x} would be at least 2000 yr. The next oxidation product to form after the U{sub 4}O{sub 9+x} phase may be U{sub 3}O{sub 8,} but no U{sub 3}O{sub 8} or other dilatational oxidation product has been detected in these accelerated tests conducted up to 25,000 h.

  19. Oxidation Behavior and Mechanism of Pentlandite at 973 K (700 °C) in Air

    NASA Astrophysics Data System (ADS)

    Zhu, Huihui; Chen, Jun; Deng, Jinxia; Yu, Ranbo; Xing, Xianran

    2012-06-01

    The oxidation behavior of synthetic pentlandite at 973 K (700 °C) under isothermal conditions was investigated. The pentlandite sample (Ni,Fe)9S8 was synthesized from pure components and oxidized at 973 K (700 °C) in air in a muffle furnace. The phase identification and components analysis of the oxidation products were performed by using the Rietveld quantitative analysis method based on the powder X-ray diffraction (XRD) profiles and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The magnetic hysteresis loops were determined by a vibrating sample magnetometer. Fe2O3, Ni x Fe3- x O4, and NiO were dominant oxidation products, and their weight fractions changed in different ways along with the oxidation time. The nickel-rich phase and sulfur-rich phase were observed as intermediate phases in unreacted cores during oxidation, which led to the formation of gaps and holes. The oxidation reaction rate was rapid in the first 2 hours, and then it slowed down sharply.

  20. In situ characterization of Zircaloy-4 oxidation at 500 °C in dry air

    NASA Astrophysics Data System (ADS)

    Vermoyal, J. J.; Dessemond, L.; Hammou, A.; Frichet, A.

    2001-10-01

    The in situ oxidation of Zircaloy-4 at 500 °C in dry air was investigated by thermogravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS). The coating of the alloy by a platinum film as electrode material was observed as not to modify the oxidation kinetic properties. After an initial cubic rate law, a transition to a quasi-linear curve occurs. The independence of the oxidation behavior to the Pt coupling is compatible with oxygen diffusion as the rate-determining step. During the pre-transition step, the rest potential of the cell Pt/oxide/Zy-4, the color of the oxide and the modulus of the single EIS signature indicate the high non-stoichiometry of the oxide. The kinetic transition was proposed to be correlated to the degradation of the film into a partially porous layer. This alteration of the oxide is associated to the appearance of a 1.2 V constant rest potential and the modification of the impedance diagrams in two high modulus contributions. The Cole-Cole representation has been used to demonstrate that the time variation of impedance spectra is related to the oxide growth. An equivalent circuit including two RC loops in series, whose capacitances are frequency dispersed, was proposed to be related to the film structure. Fitted data show that the thickness of the assumed protective layer of the film, close to the metal-oxide interface, is time independent in agreement with a constant oxidation rate. Finally, electrical properties of this inner layer were found to be quite different in pre- and post-transition stage.

  1. Laser Cladding to Improve Oxidation Behavior of Air Plasma-Sprayed Ni-20Cr Coating on Stainless Steel Substrate

    NASA Astrophysics Data System (ADS)

    Rauf, M. Mudassar; Shahid, Muhammad; Nusair Khan, A.; Mehmood, K.

    2015-09-01

    Air plasma-sprayed Ni-20Cr coating on stainless steel (AISI-304) substrate was re-melted using CO2 laser to remove the inherent defects, i.e., porosity, splat boundaries, and oxides of air plasma-sprayed coating. The (1) uncoated, (2) air plasma-sprayed, and (3) laser-re-melted specimens were exposed to cyclic oxidation at 900 °C for a hundred cycles run. The oxidation products were characterized using XRD and SEM. Weight changes were determined after every 4th cycle; Uncoated samples showed severe oxidation indicated by substantial weight loss, whereas air plasma-coated samples demonstrated noticeable weight gain. However, oxidation resistance of laser-cladded samples was found to be significantly improved as the samples showed negligible weight change; porosity within the coating was minimized with an improvement in interface quality causing reduction in delamination damage.

  2. Parametric Evaluation of an Innovative Ultra-Violet PhotocatalyticOxidation (UVPCO) Air Cleaning Technology for Indoor Applications

    SciTech Connect

    Hodgson, Alfred T.; Sullivan, Douglas P.; Fisk, William J.

    2005-10-31

    An innovative Ultra-Violet Photocatalytic Oxidation (UVPCO) air cleaning technology employing a semitransparent catalyst coated on a semitransparent polymer substrate was evaluated to determine its effectiveness for treating mixtures of volatile organic compounds (VOCs) representative of indoor environments at low, indoor-relevant concentration levels. The experimental UVPCO contained four 30 by 30-cm honeycomb monoliths irradiated with nine UVA lamps arranged in three banks. A parametric evaluation of the effects of monolith thickness, air flow rate through the device, UV power, and reactant concentrations in inlet air was conducted for the purpose of suggesting design improvements. The UVPCO was challenged with three mixtures of VOCs. A synthetic office mixture contained 27 VOCs commonly measured in office buildings. A building product mixture was created by combining sources including painted wallboard, composite wood products, carpet systems, and vinyl flooring. The third mixture contained formaldehyde and acetaldehyde. Steady state concentrations were produced in a classroom laboratory or a 20-m{sup 3} chamber. Air was drawn through the UVPCO, and single-pass conversion efficiencies were measured from replicate samples collected upstream and downstream of the reactor. Thirteen experiments were conducted in total. In this UVPCO employing a semitransparent monolith design, an increase in monolith thickness is expected to result in general increases in both reaction efficiencies and absolute reaction rates for VOCs oxidized by photocatalysis. The thickness of individual monolith panels was varied between 1.2 and 5 cm (5 to 20 cm total thickness) in experiments with the office mixture. VOC reaction efficiencies and rates increased with monolith thickness. However, the analysis of the relationship was confounded by high reaction efficiencies in all configurations for a number of compounds. These reaction efficiencies approached or exceeded 90% for alcohols, glycol

  3. A cost benefit approach to reactor sizing and nutrient supply for biotrickling filters for air pollution control

    SciTech Connect

    Deshusses, M.A.; Cox, H.H.J.

    1999-07-01

    In the present paper, a general model was developed that allows the selection of the most cost-effective operation of biotrickling filters for air pollution control. The model was demonstrated for a typical case of industrial pollution: 10,000 m{sup 3} h{sup {minus}1} airstream contaminated with 1.5 g m{sup {minus}3} toluene. The reactor design and operation were optimized with respect to the nutrient (nitrate) loading, which influenced the pollutant elimination capacity and the rate of reactor clogging by biomass. Integration of all pertinent costs and experimental data into the model demonstrated that biotrickling filtration was very competitive compared to conventional treatment technologies. For the case studied, a treatment cost optimum was obtained at a nutrient loading of 8 g N-nitrate per cubic meter bed volume per day. The range of cost effective treatment was 4 to 30 g N-nitrate m{sup {minus}3} d{sup {minus}1}. Overall, the general approach presented herein is widely applicable for the determination of the best reactor design and the optimum reactor operating conditions.

  4. Highly enantioselective oxidative couplings of 2-naphthols catalyzed by chiral bimetallic oxovanadium complexes with either oxygen or air as oxidant.

    PubMed

    Guo, Qi-Xiang; Wu, Zhi-Jun; Luo, Zhi-Bin; Liu, Quan-Zhong; Ye, Jian-Liang; Luo, Shi-Wei; Cun, Lin-Feng; Gong, Liu-Zhu

    2007-11-14

    The chiral bimetallic oxovanadium complexes have been designed for the enantioselective oxidative coupling of 2-naphthols bearing various substituents at C6 and/or C7. The chirality transferring from the amino acid to the axis of the biphenyl in oxovanadium complexes 2 was found to occur with the use of UV and CD spectra and DFT calculation. The homo-coupling reaction with oxygen as the oxidant was promoted by 5 mol % of an oxovanadium complex derived from L-isoleucine and achiral biphenol to afford binaphthols in nearly quantitative yields with high enantioselectivities of up to 98% ee. An oxovanadium complex derived from L-isoleucine and H8-binaphthol is highly efficient at catalyzing the air-oxidized coupling of 2-naphthols with excellent enantioselectivities of up to 97% ee. 51V NMR study shows that the oxovanadium complexes have two vanadium(V) species. Kinetic studies, the cross-coupling reaction, and HRMS spectral studies on the reaction have been carried out and illustrate that two vanadium(V) species are both involved in catalysis and that the coupling reaction undergoes a radical-radical mechanism in an intramolecular manner. Quantum mechanical calculations rationalize the importance of the cooperative effects of the axial chirality matching S-amino acids on the stereocontrol of the oxidative coupling reaction. The application of the transformation in the preparation of chiral ligands and conjugated polymers confirms the importance of the current process in organic synthesis. PMID:17956093

  5. REACTOR

    DOEpatents

    Spitzer, L. Jr.

    1962-01-01

    The system conteraplates ohmically heating a gas to high temperatures such as are useful in thermonuclear reactors of the stellarator class. To this end the gas is ionized and an electric current is applied to the ionized gas ohmically to heat the gas while the ionized gas is confined to a central portion of a reaction chamber. Additionally, means are provided for pumping impurities from the gas and for further heating the gas. (AEC)

  6. 40 CFR Appendix T to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Sulfur (Sulfur...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) T Appendix T to Part 50 Protection of... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) 1. General (a) This appendix explains... ambient air quality standards for Oxides of Sulfur as measured by Sulfur Dioxide (“SO2 NAAQS”)...

  7. 40 CFR Appendix T to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Sulfur (Sulfur...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) T Appendix T to Part 50 Protection of... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) 1. General (a) This appendix explains... ambient air quality standards for Oxides of Sulfur as measured by Sulfur Dioxide (“SO2 NAAQS”)...

  8. 40 CFR Appendix T to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Sulfur (Sulfur...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) T Appendix T to Part 50 Protection of... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) 1. General (a) This appendix explains... ambient air quality standards for Oxides of Sulfur as measured by Sulfur Dioxide (“SO2 NAAQS”)...

  9. 40 CFR Appendix T to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Sulfur (Sulfur...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) T Appendix T to Part 50 Protection of... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) 1. General (a) This appendix explains... ambient air quality standards for Oxides of Sulfur as measured by Sulfur Dioxide (“SO2 NAAQS”)...

  10. Pyrrhotite Oxidation as an Indicator of Air Entrainment into Eruption Columns

    NASA Astrophysics Data System (ADS)

    Matsumoto, K.; Nakamura, M.

    2015-12-01

    Fragmented magmas in eruption columns obtain buoyancy by entrainment and heating of cold air. Theoretically, the proportion of the entrained air and temperature change of the magma fragments can be calculated through rigorous fluid dynamics, but these factors have not been evaluated from natural pyroclasts. In this study, we developed a new method for quantifying the degree of air entrainment based on pyrrhotite (Po) oxidation reactions, whose time scale corresponds to the typical duration of (sub-) Plinian eruptions (i.e., tens of seconds to a few hours). We examined pumice clasts and lava flows from the 1914-15 eruption of Sakurajima. During this event, various types of eruption were observed: Plinian eruptions with intermittent generation of clastogenic lava flow, followed by voluminous effusive lava flow. The products of Po oxidation consisted of magnetite (Mt), hematite (Hm), and their composites. The occurrence of Po and the oxides were systematically correlated with the types of eruption. In Plinian pumices, unreacted Po ± porous Mt-Hm composite reaction rims were dominant, whereas in the clastogenic lava, porous Hm occurred predominantly with scarce unreacted Po and porous Mt. In the effusive lava, a variety of Po, Mt, and Hm assemblage was observed, but Po did not coexist with Hm-rims. The porous Mt crystals in the pumice clasts were found to be Ti-free, whereas those in the effusive lava had Ti-enriched rims. These correlations were explained by considering two factors: the achieved fO2, which was controlled by the extent of fragmentation (i.e., surface area exposed to air), and duration of the maintenance of a high-T and high-fO2 condition. This study has demonstrated that the cooling timescale of pumice clasts in eruption columns can be estimated through the rate of Po oxidation reactions Po→Mt and Mt→Hm. Lavas of clastogenic origin may also be recognized from the reaction.

  11. Resistance Measurements and Activation Energies Calculations of Pure and Platinum Doped Stannic Oxide Ceramics in Air

    SciTech Connect

    Ibrahim, Zuhairi; Othman, Zulkafli; Karim, Mohd Mustamam Abd; Holland, Diane

    2007-05-09

    Pure SnO2 and Pt-SnO2 ceramics were fabricated by the dry pressing method using a pressure of 40 Mpa and sintered at 1000 deg. C. Electrical resistance measurements were made using an impedance analyzer, in air and temperatures between 25 deg. C and 450 deg. C. The change in resistance in both pure and platinum-doped stannic oxide ceramics was discussed.

  12. Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates.

    PubMed

    Naganuma, Tamaki; Traversa, Enrico

    2014-06-21

    Abundant oxygen vacancies coexisting with Ce(3+) ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce(3+) ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce(3+) ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce(3+) and Ce(4+) ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce(3+) ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce(3+) ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce(3+) ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce(3+) to Ce(4+) occurred at 350 °C in air. Highly concentrated Ce(3+) ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce(3+) stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce(3+) sites. This study also illuminates the potential interaction mechanisms of stable Ce(3+) ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. PMID:24812662

  13. Amine-Oxide Hybrid Materials for CO2 Capture from Ambient Air.

    PubMed

    Didas, Stephanie A; Choi, Sunho; Chaikittisilp, Watcharop; Jones, Christopher W

    2015-10-20

    Oxide supports functionalized with amine moieties have been used for decades as catalysts and chromatographic media. Owing to the recognized impact of atmospheric CO2 on global climate change, the study of the use of amine-oxide hybrid materials as CO2 sorbents has exploded in the past decade. While the majority of the work has concerned separation of CO2 from dilute mixtures such as flue gas from coal-fired power plants, it has been recognized by us and others that such supported amine materials are also perhaps uniquely suited to extract CO2 from ultradilute gas mixtures, such as ambient air. As unique, low temperature chemisorbents, they can operate under ambient conditions, spontaneously extracting CO2 from ambient air, while being regenerated under mild conditions using heat or the combination of heat and vacuum. This Account describes the evolution of our activities on the design of amine-functionalized silica materials for catalysis to the design, characterization, and utilization of these materials in CO2 separations. New materials developed in our laboratory, such as hyperbranched aminosilica materials, and previously known amine-oxide hybrid compositions, have been extensively studied for CO2 extraction from simulated ambient air (400 ppm of CO2). The role of amine type and structure (molecular, polymeric), support type and structure, the stability of the various compositions under simulated operating conditions, and the nature of the adsorbed CO2 have been investigated in detail. The requirements for an effective, practical air capture process have been outlined and the ability of amine-oxide hybrid materials to meet these needs has been discussed. Ultimately, the practicality of such a "direct air capture" process is predicated not only on the physicochemical properties of the sorbent, but also how the sorbent operates in a practical process that offers a scalable gas-solid contacting strategy. In this regard, the utility of low pressure drop monolith

  14. A study of mercuric oxide and zinc-air battery life in hearing aids.

    PubMed

    Sparkes, C; Lacey, N K

    1997-09-01

    The requirement to phase out mercuric oxide (mercury) batteries on environmental grounds has led to the widespread introduction of zinc-air technology. The possibility arises that high drain hearing aids may not be adequately catered for by zinc-air cells, leading to poor performance. This study investigated the hearing aid user's ability to perceive differences between zinc-air and mercury cells in normal everyday usage. The data was collected for 100 experienced hearing aid users in field trials. Users report 50 per cent greater life for zinc-air cells in high power aids and 28 per cent in low power aids. The average life of the zinc-air cells range from 15 days in high power to 34 days in low power aids. Users are able to perceive a difference in sound quality in favour of zinc-air cells for low and medium power aids. The hearing aid population is not disadvantaged by phasing out mercury cells. PMID:9373545

  15. Using advanced oxidation treatment for biofilm inactivation by varying water vapor content in air plasma

    NASA Astrophysics Data System (ADS)

    Ryota, Suganuma; Koichi, Yasuoka

    2015-09-01

    Biofilms are caused by environmental degradation in food factories and medical facilities. The inactivation of biofilms involves making them react with chemicals including chlorine, hydrogen peroxide, and ozone, although inactivation using chemicals has a potential problem because of the hazardous properties of the residual substance and hydrogen peroxide, which have slow reaction velocity. We successfully performed an advanced oxidation process (AOP) using air plasma. Hydrogen peroxide and ozone, which were used for the formation of OH radicals in our experiment, were generated by varying the amount of water vapor supplied to the plasma. By varying the content of the water included in the air, the main product was changed from air plasma. When we increased the water content in the air, hydrogen peroxide was produced, while ozone peroxide was produced when we decreased the water content in the air. By varying the amount of water vapor, we realized a 99.9% reduction in the amount of bacteria in the biofilm when we discharged humidified air only. This work was supported by JSPS KAKENHI Grant Number 25630104.

  16. Method and apparatus for enhancing reactor air-cooling system performance

    DOEpatents

    Hunsbedt, Anstein

    1996-01-01

    An enhanced decay heat removal system for removing heat from the inert gas-filled gap space between the reactor vessel and the containment vessel of a liquid metal-cooled nuclear reactor. Multiple cooling ducts in flow communication with the inert gas-filled gap space are incorporated to provide multiple flow paths for the inert gas to circulate to heat exchangers which remove heat from the inert gas, thereby introducing natural convection flows in the inert gas. The inert gas in turn absorbs heat directly from the reactor vessel by natural convection heat transfer.

  17. Method and apparatus for enhancing reactor air-cooling system performance

    DOEpatents

    Hunsbedt, A.

    1996-03-12

    An enhanced decay heat removal system is disclosed for removing heat from the inert gas-filled gap space between the reactor vessel and the containment vessel of a liquid metal-cooled nuclear reactor. Multiple cooling ducts in flow communication with the inert gas-filled gap space are incorporated to provide multiple flow paths for the inert gas to circulate to heat exchangers which remove heat from the inert gas, thereby introducing natural convection flows in the inert gas. The inert gas in turn absorbs heat directly from the reactor vessel by natural convection heat transfer. 6 figs.

  18. Modeling of simultaneous anaerobic methane and ammonium oxidation in a membrane biofilm reactor.

    PubMed

    Chen, Xueming; Guo, Jianhua; Shi, Ying; Hu, Shihu; Yuan, Zhiguo; Ni, Bing-Jie

    2014-08-19

    Nitrogen removal by using the synergy of denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (Anammox) microorganisms in a membrane biofilm reactor (MBfR) has previously been demonstrated experimentally. In this work, a mathematical model is developed to describe the simultaneous anaerobic methane and ammonium oxidation by DAMO and Anammox microorganisms in an MBfR for the first time. In this model, DAMO archaea convert nitrate, both externally fed and/or produced by Anammox, to nitrite, with methane as the electron donor. Anammox and DAMO bacteria jointly remove the nitrite fed/produced, with ammonium and methane as the electron donor, respectively. The model is successfully calibrated and validated using the long-term (over 400 days) dynamic experimental data from the MBfR, as well as two independent batch tests at different operational stages of the MBfR. The model satisfactorily describes the methane oxidation and nitrogen conversion data from the system. Modeling results show the concentration gradients of methane and nitrogen would cause stratification of the biofilm, where Anammox bacteria mainly grow in the biofilm layer close to the bulk liquid and DAMO organisms attach close to the membrane surface. The low surface methane loadings result in a low fraction of DAMO microorganisms, but the high surface methane loadings would lead to overgrowth of DAMO bacteria, which would compete with Anammox for nitrite and decrease the fraction of Anammox bacteria. The results suggest an optimal methane supply under the given condition should be applied not only to benefit the nitrogen removal but also to avoid potential methane emissions. PMID:25055054

  19. Experimental study of the oxidation of methyl oleate in a jet-stirred reactor

    SciTech Connect

    Bax, Sarah; Hakka, Mohammed Hichem; Glaude, Pierre-Alexandre; Herbinet, Olivier; Battin-Leclerc, Frederique

    2010-06-15

    The experimental study of the oxidation of a blend containing n-decane and a large unsaturated ester, methyl oleate, was performed in a jet-stirred reactor over a wide range of temperature covering both low and high temperature regions (550-1100 K), at a residence time of 1.5 s, at quasi atmospheric pressure with high dilution in helium (n-decane and methyl oleate inlet mole fractions of 1.48 x 10{sup -3} and 5.2 x 10{sup -4}) and under stoichiometric conditions. The formation of numerous reaction products was observed. At low and intermediate temperatures, the oxidation of the blend led to the formation of species containing oxygen atoms like cyclic ethers, aldehydes and ketones deriving from n-decane and methyl oleate. At higher temperature, these species were not formed anymore and the presence of unsaturated species was observed. Because of the presence of the double bond in the middle of the alkyl chain of methyl oleate, the formation of some specific products was observed. These species are dienes and esters with two double bonds produced from the decomposition paths of methyl oleate and some species obtained from the addition of H-atoms, OH and HO{sub 2} radicals to the double bond. Experimental results were compared with former results of the oxidation of a blend of n-decane and methyl palmitate performed under similar conditions. This comparison allowed highlighting the similarities and the differences in the reactivity and in the distribution of the reaction products for the oxidation of large saturated and unsaturated esters. (author)

  20. Experimental study of the oxidation of methyl oleate in a jet-stirred reactor

    PubMed Central

    Bax, Sarah; Hakka, Mohammed Hichem; Glaude, Pierre-Alexandre; Herbinet, Olivier; Battin-Leclerc, Frédérique

    2013-01-01

    The experimental study of the oxidation of a blend containing n-decane and a large unsaturated ester, methyl oleate, was performed in a jet-stirred reactor over a wide range of temperature covering both low and high temperature regions (550–1100 K), at a residence time of 1.5 s, at quasi atmospheric pressure with high dilution in helium (n-decane and methyl oleate inlet mole fractions of 1.48 × 10−3 and 5.2 × 10−4) and under stoichiometric conditions. The formation of numerous reaction products was observed. At low and intermediate temperatures, the oxidation of the blend led to the formation of species containing oxygen atoms like cyclic ethers, aldehydes and ketones deriving from n-decane and methyl oleate. At higher temperature, these species were not formed anymore and the presence of unsaturated species was observed. Because of the presence of the double bond in the middle of the alkyl chain of methyl oleate, the formation of some specific products was observed. These species are dienes and esters with two double bonds produced from the decomposition paths of methyl oleate and some species obtained from the addition of H-atoms, OH and HO2 radicals to the double bond. Experimental results were compared with former results of the oxidation of a blend of n-decane and methyl palmitate performed under similar conditions. This comparison allowed highlighting the similarities and the differences in the reactivity and in the distribution of the reaction products for the oxidation of large saturated and unsaturated esters. PMID:23710077

  1. Simulation for supporting scale-up of a fluidized bed reactor for advanced water oxidation.

    PubMed

    Tisa, Farhana; Raman, Abdul Aziz Abdul; Daud, Wan Mohd Ashri Wan

    2014-01-01

    Simulation of fluidized bed reactor (FBR) was accomplished for treating wastewater using Fenton reaction, which is an advanced oxidation process (AOP). The simulation was performed to determine characteristics of FBR performance, concentration profile of the contaminants, and various prominent hydrodynamic properties (e.g., Reynolds number, velocity, and pressure) in the reactor. Simulation was implemented for 2.8 L working volume using hydrodynamic correlations, continuous equation, and simplified kinetic information for phenols degradation as a model. The simulation shows that, by using Fe(3+) and Fe(2+) mixtures as catalyst, TOC degradation up to 45% was achieved for contaminant range of 40-90 mg/L within 60 min. The concentration profiles and hydrodynamic characteristics were also generated. A subsequent scale-up study was also conducted using similitude method. The analysis shows that up to 10 L working volume, the models developed are applicable. The study proves that, using appropriate modeling and simulation, data can be predicted for designing and operating FBR for wastewater treatment. PMID:25309949

  2. A flow reactor study of neopentane oxidation at 8 atmospheres: Experiments and modeling

    SciTech Connect

    Wang, S.; Miller, D.L.; Cernansky, N.P.; Curran, H.J.; Pitz, W.J.; Westbrook, C.K.

    1999-08-01

    An existing detailed chemical kinetic reaction mechanism for neopentane oxidation is applied to new experimental measurements, taken in a flow reactor operating at a pressure of 8 atm. The reactor temperature ranged from 620 K to 810 K and flow rates of the reactant gases neopentane, oxygen, and nitrogen were 0.285, 7.6, and 137.1 standard liter per minute (SLM), respectively, producing an equivalence ratio of 0.3. Initial simulations identified some deficiencies in the existing model and the paper presents modifications which included upgrading the thermodynamic parameters of alkyl radical and alkylperoxy radical species, adding an alternative isomerization reaction of hydroperoxy-neopentyl-peroxy, and a multistep reaction sequence for 2-methylpropan-2-yl radical with molecular oxygen. These changes improved the calculation for the overall reactivity and the concentration profiles of the following primary products: formaldehyde, acetone, isobutene; 3,3-dimethyloxetane, methacrolein, carbon monoxide, carbon dioxide, and water. Experiments indicate that neopentane shows negative temperature coefficient behavior similar to other alkanes, though it is not as pronounced as that shown by n-pentane for example. Modeling results indicate that this behavior is caused by the {beta}-scission of the neopentyl radical and the chain propagation reactions of the hydroperoxyl-neopentyl radical.

  3. Simulation for Supporting Scale-Up of a Fluidized Bed Reactor for Advanced Water Oxidation

    PubMed Central

    Abdul Raman, Abdul Aziz; Daud, Wan Mohd Ashri Wan

    2014-01-01

    Simulation of fluidized bed reactor (FBR) was accomplished for treating wastewater using Fenton reaction, which is an advanced oxidation process (AOP). The simulation was performed to determine characteristics of FBR performance, concentration profile of the contaminants, and various prominent hydrodynamic properties (e.g., Reynolds number, velocity, and pressure) in the reactor. Simulation was implemented for 2.8 L working volume using hydrodynamic correlations, continuous equation, and simplified kinetic information for phenols degradation as a model. The simulation shows that, by using Fe3+ and Fe2+ mixtures as catalyst, TOC degradation up to 45% was achieved for contaminant range of 40–90 mg/L within 60 min. The concentration profiles and hydrodynamic characteristics were also generated. A subsequent scale-up study was also conducted using similitude method. The analysis shows that up to 10 L working volume, the models developed are applicable. The study proves that, using appropriate modeling and simulation, data can be predicted for designing and operating FBR for wastewater treatment. PMID:25309949

  4. Analysis of a gas-liquid film plasma reactor for organic compound oxidation.

    PubMed

    Hsieh, Kevin; Wang, Huijuan; Locke, Bruce R

    2016-11-01

    A pulsed electrical discharge plasma formed in a tubular reactor with flowing argon carrier gas and a liquid water film was analyzed using methylene blue as a liquid phase hydroxyl radical scavenger and simultaneous measurements of hydrogen peroxide formation. The effects of liquid flow rate, liquid conductivity, concentration of dye, and the addition of ferrous ion on dye decoloration and degradation were determined. Higher liquid flow rates and concentrations of dye resulted in less decoloration percentages and hydrogen peroxide formation due to initial liquid conductivity effects and lower residence times in the reactor. The highest decoloration energy yield of dye found in these studies was 5.2g/kWh when using the higher liquid flow rate and adding the catalyst. The non-homogeneous nature of the plasma discharge favors the production of hydrogen peroxide in the plasma-liquid interface over the chemical oxidation of the organic in the bulk liquid phase and post-plasma reactions with the Fenton catalyst lead to complete utilization of the plasma-formed hydrogen peroxide. PMID:27267693

  5. Treatment of municipal landfill leachate by catalytic wet air oxidation: Assessment of the role of operating parameters by factorial design

    SciTech Connect

    Anglada, Angela; Urtiaga, Ane; Ortiz, Inmaculada; Diamadopoulos, Evan

    2011-08-15

    Highlights: > Landfill leachates can be treated effectively by catalytic wet oxidation. > Addition of H{sub 2}O{sub 2} in the presence of transition metals promotes degradation. > Factorial design evaluates the statistically significant operating conditions. > H{sub 2}O{sub 2}, reaction time and temperature are critical in determining performance. - Abstract: The wet air oxidation (WAO) of municipal landfill leachate catalyzed by cupric ions and promoted by hydrogen peroxide was investigated. The effect of operating conditions such as WAO treatment time (15-30 min), temperature (160-200 deg. C), Cu{sup 2+} concentration (250-750 mg L{sup -1}) and H{sub 2}O{sub 2} concentration (0-1500 mg L{sup -1}) on chemical oxygen demand (COD) removal was investigated by factorial design considering a two-stage, sequential process comprising the heating-up of the reactor and the actual WAO. The leachate, at an initial COD of 4920 mg L{sup -1}, was acidified to pH 3 leading to 31% COD decrease presumably due to the coagulation/precipitation of colloidal and other organic matter. During the 45 min long heating-up period of the WAO reactor under an inert atmosphere, COD removal values up to 35% (based on the initial COD value) were recorded as a result of the catalytic decomposition of H{sub 2}O{sub 2} to reactive hydroxyl radicals. WAO at 2.5 MPa oxygen partial pressure advanced treatment further; for example, 22 min of oxidation at 200 deg. C, 250 mg L{sup -1} Cu{sup 2+} and 0-1500 mg L{sup -1} H{sub 2}O{sub 2} resulted in an overall (i.e. including acidification and heating-up) COD reduction of 78%. Amongst the operating variables in question, temperature had the strongest influence on both the heating-up and WAO stages, while H{sub 2}O{sub 2} concentration strongly affected the former and reaction time the latter. Nonetheless, the effects of temperature and H{sub 2}O{sub 2} concentration were found to depend on the concentration levels of catalyst as suggested by the

  6. Formation and growth of indoor air aerosol particles as a result of D-limonene oxidation

    NASA Astrophysics Data System (ADS)

    Vartiainen, E.; Kulmala, M.; Ruuskanen, T. M.; Taipale, R.; Rinne, J.; Vehkamäki, H.

    Oxidation of D-limonene, which is a common monoterpene, can lead to new aerosol particle formation in indoor environments. Thus, products containing D-limonene, such as citrus fruits, air refresheners, household cleaning agents, and waxes, can act as indoor air aerosol particle sources. We released D-limonene into the room air by peeling oranges and measured the concentration of aerosol particles of three different size ranges. In addition, we measured the concentration of D-limonene, the oxidant, and the concentration of ozone, the oxidizing gas. Based on the measurements we calculated the growth rate of the small aerosol particles, which were 3-10 nm in diameter, to be about 6300nmh-1, and the losses of the aerosol particles that were due to the coagulation and condensation processes. From these, we further approximated the concentration of the condensable vapour and its source rate and then calculated the formation rate of the small aerosol particles. For the final result, we calculated the nucleation rate and the maximum number of molecules in a critical cluster. The nucleation rate was in the order of 105cm-3s-1 and the number of molecules in a critical-sized cluster became 1.2. The results were in agreement with the activation theory.

  7. Solid oxide fuel cells, and air electrode and electrical interconnection materials therefor

    DOEpatents

    Bates, J.L.

    1992-09-01

    In one aspect of the invention, an air electrode material for a solid oxide fuel cell comprises Y[sub 1[minus]a]Q[sub a]MnO[sub 3], where Q is selected from the group consisting of Ca and Sr or mixtures thereof and a' is from 0.1 to 0.8. Preferably, a' is from 0.4 to 0.7. In another aspect of the invention, an electrical interconnection material for a solid oxide fuel cell comprises Y[sub 1[minus]b]Ca[sub b]Cr[sub 1[minus]c]Al[sub c]O[sub 3], where b' is from 0.1 to 0.6 and c' is from 0 to 9.3. Preferably, b' is from 0.3 to 0.5 and c' is from 0.05 to 0.1. A composite solid oxide electrochemical fuel cell incorporating these materials comprises: a solid oxide air electrode and an adjacent solid oxide electrical interconnection which commonly include the cation Y, the air electrode comprising Y[sub 1[minus]a]Q[sub a]MnO[sub 3], where Q is selected from the group consisting of Ca and Sr or mixtures thereof and a' is from 0.1 to 0.8, the electrical interconnection comprising Y[sub 1[minus]b]Ca[sub b]Cr[sub 1[minus]c]Al[sub c]O[sub 3], where b' is from 0.1 to 0.6 and c' is from 0.0 to 0.3; a yttrium stabilized solid electrolyte comprising (1[minus]d)ZrO[sub 2]-(d)Y[sub 2]O[sub 3] where d' is from 0.06 to 0.5; and a solid fuel electrode comprising X-ZrO[sub 2], where X' is an elemental metal. 5 figs.

  8. Solid oxide fuel cells, and air electrode and electrical interconnection materials therefor

    DOEpatents

    Bates, J. Lambert

    1992-01-01

    In one aspect of the invention, an air electrode material for a solid oxide fuel cell comprises Y.sub.1-a Q.sub.a MnO.sub.3, where "Q" is selected from the group consisting of Ca and Sr or mixtures thereof and "a" is from 0.1 to 0.8. Preferably, "a" is from 0.4 to 0.7. In another aspect of the invention, an electrical interconnection material for a solid oxide fuel cell comprises Y.sub.1-b Ca.sub.b Cr.sub.1-c Al.sub.c O.sub.3, where "b" is from 0.1 to 0.6 and "c" is from 0 to 9.3. Preferably, "b" is from 0.3 to 0.5 and "c" is from 0.05 to 0.1. A composite solid oxide electrochemical fuel cell incorporating these materials comprises: a solid oxide air electrode and an adjacent solid oxide electrical interconnection which commonly include the cation Y, the air electrode comprising Y.sub.1-a Q.sub.a MnO.sub.3, where "Q" is selected from the group consisting of Ca and Sr or mixtures thereof and "a" is from 0.1 to 0.8, the electrical interconnection comprising Y.sub.1-b Ca.sub.b Cr.sub.1-c Al.sub.c O.sub.3, where "b" is from 0.1 to 0.6 and "c" is from 0.0 to 0.3; a yttrium stabilized solid electrolyte comprising (1-d)ZrO.sub.2 -(d)Y.sub.2 O.sub.3 where "d" is from 0.06 to 0.5; and a solid fuel electrode comprising X-ZrO.sub.2, where "X" is an elemental metal.

  9. STUDY OF MERCURY OXIDATION BY SCR CATALYST IN AN ENTRAINED-FLOW REACTOR UNDER SIMULATED PRB CONDITIONS

    EPA Science Inventory

    A bench-scale entrained-flow reactor system was constructed for studying elemental mercury oxidation under selective catalytic reduction (SCR) reaction conditions. Simulated flue gas was doped with fly ash collected from a subbituminous Powder River Basin (PRB) coal-fired boiler ...

  10. THE PHOTOCATALYTIC OXIDATION OF LOW CONCENTRATION MTBE ON TITANIUM DIOXIDE FROM GROUNDWATER IN A FALLING FILM REACTOR

    EPA Science Inventory

    This study focuses on three objectives: 1) to determine the feasibility of using a falling-film slurry photocatalytic reactor for the degradation of MTBE in water, 2) to assess the feasibility of MTBE photo-oxidation on TiO2 at low initial MTBE concentrations (<10 mg/L), and 3) t...

  11. Mortality from asthma and chronic bronchitis associated with changes in sulfur oxides air pollution

    SciTech Connect

    Imai, M.; Yoshida, K.; Kitabatake, M.

    1986-01-01

    Death certificates issued in Yokkaichi, Japan, during the 21 yr from 1963 until 1983 were surveyed to determine the relationship between changes in air pollution and mortality due to bronchial asthma and chronic bronchitis. The following results were obtained. In response to worsening air pollution, mortality for bronchial asthma and chronic bronchitis began to increase. Mortality due to bronchial asthma decreased immediately in response to improvement of pollution, whereas mortality due to chronic bronchitis decreased to the level in the control area 4 to 5 yr after the concentration of sulfur dioxide (SO/sub 2/) began to satisfy the ambient air quality standard. In the polluted area, mortality due to bronchial asthma in subjects who were 20 yr of age was higher during the period in which higher concentrations of sulfur oxides were prevalent.

  12. Evaluation of Ultra-Violet Photocatalytic Oxidation for Indoor AirApplications

    SciTech Connect

    Hodgson, A.T.; Sullivan, D.P.; Fisk, W.J.

    2006-02-01

    Acceptable indoor air quality in office buildings may be achieved with less energy by combining effective air cleaning systems for volatile organic compounds (VOCs) with particle filtration then by relying solely on ventilation. For such applications, ultraviolet photocatalytic oxidation (UVPCO) systems are being developed for VOC destruction. An experimental evaluation of a UVPCO system is reported. The evaluation was unique in that it employed complex mixtures of VOCs commonly found in office buildings at realistically low concentrations. VOC conversion efficiencies varied over a broad range, usually exceeded 20%, and were as high as {approx}80%. Conversion efficiency generally diminished with increased air flow rate. Significant amounts of formaldehyde and acetaldehyde were produced due to incomplete mineralization. The results indicate that formaldehyde and acetaldehyde production rates may need to be reduced before such UVPCO systems can be deployed safely in occupied buildings.

  13. Low cost stable air electrode material for high temperature solid oxide electrolyte electrochemical cells

    DOEpatents

    Kuo, L.J.H.; Singh, P.; Ruka, R.J.; Vasilow, T.R.; Bratton, R.J.

    1997-11-11

    A low cost, lanthanide-substituted, dimensionally and thermally stable, gas permeable, electrically conductive, porous ceramic air electrode composition of lanthanide-substituted doped lanthanum manganite is provided which is used as the cathode in high temperature, solid oxide electrolyte fuel cells and generators. The air electrode composition of this invention has a much lower fabrication cost as a result of using a lower cost lanthanide mixture, either a natural mixture or an unfinished lanthanide concentrate obtained from a natural mixture subjected to incomplete purification, as the raw material in place of part or all of the higher cost individual lanthanum. The mixed lanthanide primarily contains a mixture of at least La, Ce, Pr, and Nd, or at least La, Ce, Pr, Nd and Sm in its lanthanide content, but can also include minor amounts of other lanthanides and trace impurities. The use of lanthanides in place of some or all of the lanthanum also increases the dimensional stability of the air electrode. This low cost air electrode can be fabricated as a cathode for use in high temperature, solid oxide fuel cells and generators. 4 figs.

  14. Low cost stable air electrode material for high temperature solid oxide electrolyte electrochemical cells

    DOEpatents

    Kuo, Lewis J. H.; Singh, Prabhakar; Ruka, Roswell J.; Vasilow, Theodore R.; Bratton, Raymond J.

    1997-01-01

    A low cost, lanthanide-substituted, dimensionally and thermally stable, gas permeable, electrically conductive, porous ceramic air electrode composition of lanthanide-substituted doped lanthanum manganite is provided which is used as the cathode in high temperature, solid oxide electrolyte fuel cells and generators. The air electrode composition of this invention has a much lower fabrication cost as a result of using a lower cost lanthanide mixture, either a natural mixture or an unfinished lanthanide concentrate obtained from a natural mixture subjected to incomplete purification, as the raw material in place of part or all of the higher cost individual lanthanum. The mixed lanthanide primarily contains a mixture of at least La, Ce, Pr, and Nd, or at least La, Ce, Pr, Nd and Sm in its lanthanide content, but can also include minor amounts of other lanthanides and trace impurities. The use of lanthanides in place of some or all of the lanthanum also increases the dimensional stability of the air electrode. This low cost air electrode can be fabricated as a cathode for use in high temperature, solid oxide fuel cells and generators.

  15. Impact of clay mineral on air oxidation of PAH-contaminated soils.

    PubMed

    Biache, Coralie; Kouadio, Olivier; Lorgeoux, Catherine; Faure, Pierre

    2014-09-01

    This work investigated the impact of a clay mineral (bentonite) on the air oxidation of the solvent extractable organic matters (EOMs) and the PAHs from contaminated soils. EOMs were isolated from two coking plant soils and mixed with silica sand or bentonite. These samples, as well as raw soils and bentonite/soil mixtures, were oxidized in air at 60 and 100 °C for 160 days. Mineralization was followed by measuring the CO2 produced over the experiments. EOM, polycyclic aromatic compound (PAC), including PAH, contents were also determined. Oxidation led to a decrease in EOM contents and PAH concentrations, these diminutions were enhanced by the presence of bentonite. Transfer of carbon from EOM to insoluble organic matter pointed out a condensation phenomenon leading to a stabilization of the contamination. Higher mineralization rates, observed during the oxidation of the soil/bentonite mixtures, seem to indicate that this clay mineral had a positive influence on the transformation of PAC into CO2. PMID:24816462

  16. Removal of ammonia from air on molybdenum and tungsten oxide modified activated carbons.

    PubMed

    Petit, Camille; Bandosz, Teresa J

    2008-04-15

    Microporous coconut-based activated carbon was impregnated with solutions of ammonium metatungstate or ammonium molybdate and then calcined in air in order to convert the salts into their corresponding oxides. The surface of those materials was characterized using adsorption of nitrogen, potentiometric titration, Fourier-transform infrared spectroscopy, X-ray diffraction, and thermal analysis. The results indicated a significant increase in surface acidity related to the presence of tungsten or molybdenum oxides. On the materials obtained, adsorption of ammonia from either dry or moist air was carried out. The oxides distributed on the surface provided Lewis and/or Brønsted centers for interactions with ammonia molecules or ammonium ions. Water on the surface of carbon or in the gas phase increased the amount of ammonia adsorbed via involvement of Brønsted-type interactions and/or by leading to the formation of molybdate or tungstate salts on the surface. Although the amount of ammonia adsorbed is closely related to the number of moles of oxides and their acidic centers, the carbon surface also contributes to the adsorption via providing small pores where ammonia can be dissolved in the water film. PMID:18497162

  17. Investigation of Room Temperature Oxidation of Cu in Air by Yoneda-XAFS

    SciTech Connect

    Keil, P.; Luetzenkirchen-Hecht, D.; Frahm, R.

    2007-02-02

    The structure of thin copper oxide layers which are formed on metallic Cu due to the exposure to air are investigated with Yoneda-XAFS and ReflEXAFS. The measured Yoneda-XAFS data were compared to quantitative model calculations in the framework of the distorted wave Born approximation (DWBA) assuming different model structures for the oxide layer. Yoneda-XAFS fine structure spectra measured for various different grazing angles show that the experimental data are best described by a model structure consisting of a duplex type oxide layer with an outer layer of CuO (tenorite) in direct contact with the gas atmosphere and an inner Cu2O (cuprite) layer at the interface to the underlying Cu metal.

  18. Carbon catalysis in the aqueous oxidation of SO2 by NO2 and air

    NASA Technical Reports Server (NTRS)

    Schryer, D. R.; Schryer, J.; Cofer, W. R., III; Vay, S. A.

    1984-01-01

    Sulfur dioxide and an oxidant gas (air or NO2) were bubbled through aqueous suspensions of both washed and unwashed carbon black as well as through samples of wash water, which contained whatever soluble species were originally present on the carbon, and high-purity water. The sulfate yields obtained showed the washed and unwashed carbon to be equally catalytic for the oxidation of SO2 to sulfate by both oxidants, whereas little sulfate was generated in either the wash water or high-purity water in the absence of carbon. These results indicate that the sulfate yields produced in aqueous suspensions of the carbon studied are due to catalysis by the carbon particles rather than by soluble species dissolved from them.

  19. Validations of CFD Code for Density-Gradient Driven Air Ingress Stratified Flow

    SciTech Connect

    Chang H. Oh; Eung S. Kim; Richard Schultz; David Petti

    2010-05-01

    Air ingress into a very high temperature gas-cooled reactor (VHTR) is an important phenomena to consider because the air oxidizes the reactor core and lower plenum where the graphite structure supports the core region in the gas turbine modular helium reactor (GTMHR) design, thus jeopardizing the reactor’s safety. Validating the computational fluid dynamics (CFD) code used to analyze the air ingress phenomena is therefore an essential part of the safety analysis and the ultimate computation required for licensing

  20. Comparison of measured and calculated air-transported radiation from a fast unshielded nuclear reactor. Technical report

    SciTech Connect

    Robitaille, H.A.; Hoffarth, B.E.

    1980-12-01

    Neutron and gamma-ray spectra have been measured at various distances up to 1100 metres from the fast-neutron reactor of the U.S. Army Pulse Radiation Division (Materiel Testing Directorate, Aberdeen Proving Ground, Md.) The spectra were obtained at a height of two metres above the air-ground interface and are compared to previous measurements performed by two other research laboratories, and also to the results of theoretical predictions based on two-dimensional discrete-ordinates transport theory. Integral quantities such as partial and total radiation kermas are generally in good agreement, however the theoretical calculations tend to predict somewhat softer neutron spectra than are observed experimentally.

  1. Laboratory validation and field verification of a new passive air monitoring badge for sampling ethylene oxide in air.

    PubMed

    Kring, E V; Damrell, D J; Basilio, A N; McGibney, P D; Douglas, J J; Henry, T J; Ansul, G R

    1984-10-01

    A new diffusion colorimetric air monitoring badge for sampling ethylene oxide is described. The Du Pont Pro-Tek C-70 badge has been laboratory validated over the range of 4-375 ppm-hours (0.5-47 ppm on an 8-hour TWA) using standard spectrophotometer readout in 1 centimeter (10 mm) cells. The lower range can be extended to 2 ppm-hours (0.25 ppm) by using 4 cm (40 mm) cells. The badge has an overall sampling and analytical method accuracy of +/- 13.5%. It meets NIOSH accuracy criteria and has a mean coefficient of variation CVT = 0.059. The badge has no temperature, pressure, relative humidity or face velocity effects over practical ranges. The response time is adequate to sample peak concentrations over short time periods. The badge may be used to determine ambient formaldehyde levels if suspected to be present along with ethylene oxide. Badges are shown to agree very well with the industry accepted and proposed ASTM pump/charcoal tube method in three extensive plant field tests. Badges were more precise than the charcoal tube/pump method in all field tests conducted. PMID:6496316

  2. Cast Stone Oxidation Front Evaluation: Preliminary Results For Samples Exposed To Moist Air

    SciTech Connect

    Langton, C. A.; Almond, P. M.

    2013-11-26

    The rate of oxidation is important to the long-term performance of reducing salt waste forms because the solubility of some contaminants, e.g., technetium, is a function of oxidation state. TcO{sub 4}{sup -} in the salt solution is reduced to Tc(IV) and has been shown to react with ingredients in the waste form to precipitate low solubility sulfide and/or oxide phases. Upon exposure to oxygen, the compounds containing Tc(IV) oxidize to the pertechnetate ion, Tc(VII)O{sub 4}{sup -}, which is very soluble. Consequently the rate of technetium oxidation front advancement into a monolith and the technetium leaching profile as a function of depth from an exposed surface are important to waste form performance and ground water concentration predictions. An approach for measuring contaminant oxidation rate (effective contaminant specific oxidation rate) based on leaching of select contaminants of concern is described in this report. In addition, the relationship between reduction capacity and contaminant oxidation is addressed. Chromate (Cr(VI) was used as a non-radioactive surrogate for pertechnetate, Tc(VII), in Cast Stone samples prepared with 5 M Simulant. Cast Stone spiked with pertechnetate was also prepared and tested. Depth discrete subsamples spiked with Cr were cut from Cast Stone exposed to Savannah River Site (SRS) outdoor ambient temperature fluctuations and moist air. Depth discrete subsamples spiked with Tc-99 were cut from Cast Stone exposed to laboratory ambient temperature fluctuations and moist air. Similar conditions are expected to be encountered in the Cast Stone curing container. The leachability of Cr and Tc-99 and the reduction capacities, measured by the Angus-Glasser method, were determined for each subsample as a function of depth from the exposed surface. The results obtained to date were focused on continued method development and are preliminary and apply to the sample composition and curing / exposure conditions described in this report. The

  3. Improving the oxidation resistance of 316L stainless steel in simulated pressurized water reactor primary water by electropolishing treatment

    NASA Astrophysics Data System (ADS)

    Han, Guangdong; Lu, Zhanpeng; Ru, Xiangkun; Chen, Junjie; Xiao, Qian; Tian, Yongwu

    2015-12-01

    The oxidation behavior of 316L stainless steel specimens after emery paper grounding, mechanical polishing, and electropolishing were investigated in simulated pressurized water reactor primary water at 310 °C for 120 and 500 h. Electropolishing afforded improved oxidation resistance especially during the early immersion stages. Duplex oxide films comprising a coarse Fe-rich outer layer and a fine Cr-rich inner layer formed on all specimens after 500 h of immersion. Only a compact layer was observed on the electropolished specimen after 120 h of immersion. The enrichment of chromium in the electropolished layer contributed to the passivity and protectiveness of the specimen.

  4. Post-treatment of anaerobic reactor effluent using coagulation/oxidation followed by double filtration.

    PubMed

    Cavallini, Grasiele Soares; de Sousa Vidal, Carlos Magno; de Souza, Jeanette Beber; de Campos, Sandro Xavier

    2016-04-01

    This study evaluates the efficacy of a sanitary sewage treatment system, proposing post-treatment of the effluent generated by the upflow anaerobic sludge blanket UASB reactor, through a Fenton coagulation/oxidation ((ferric chloride (FC) or ferrous sulfate (FS) and peracetic acid (PAA)), followed by a double filtration system, composed of a gravel ascending drainage filter and a sand descending filter. Following the assessment of treatability, the system efficiency was evaluated using physicochemical and microbiological parameters. In all treatments performed in the pilot unit, total suspended solids (TSS) were completely removed, leading to a decrease in turbidity greater than 90% and close to 100% removal of total phosphorous. In the FC and PAA combination, the effluent was oxygenated prior to filtration, enabling a more significant removal of biochemical oxygen demand (BOD), which characterizes aerobic degradation even in a quick sand filter. The treatments carried out in the presence of the PAA oxidizing agent showed a more significant bleaching of the effluent. Concerning the microbiological parameters, the simultaneous use of PAA and FC contributed to the partial inactivation of the assessed microorganisms. A 65% recovery of the effluent was obtained with the proposed treatment system, considering the volume employed in filter backwashing. PMID:26611629

  5. Thermochemical Analysis of Gas-Cooled Reactor Fuels Containing Am and Pu Oxides

    SciTech Connect

    Lindemer, T.B.

    2002-09-05

    Literature values and estimated data for the thermodynamics of the actinide oxides and fission products are applied to explain the chemical behavior in gas-cooled-reactor fuels. Emphasis is placed on the Am-O-C and Pu-O-C systems and the data are used to plot the oxygen chemical potential versus temperature of solid-solid and solid-gas equilibria. These results help explain observations of vaporization in Am oxides, nitrides, and carbides and provide guidance for the ceramic processing of the fuels. The thermodynamic analysis is then extended to the fission product systems and the Si-C-O system. Existing data on oxygen release (primarily as CO) as a function of burnup in the thoria-urania fuel system is reviewed and compared to values calculated from thermodynamic data. The calculations of oxygen release are then extended to the plutonia and americia fuels. Use of ZrC not only as a particle coating that may be more resistant to corrosion by Pd and other noble-metal fission products, but also as a means to getter oxygen released by fission is discussed.

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

    PubMed

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

    2011-04-01

    The hydrothermal flame is a new method of combustion that takes place in supercritical water oxidation reactions when the temperature is higher than the autoignition temperature. In these conditions, waste can be completely mineralized in residence times of milliseconds without the formation of by-products typical of conventional combustion. The object of this work is to study the hydrothermal flame formation in aqueous streams with high concentrations of recalcitrant compounds: an industrial waste with a high concentration of acetic acid and various concentrated solutions of ammonia. A tubular reactor with a residence time of 0.7 s was used. Oxygen was used as the oxidant and isopropyl alcohol (IPA) as co-fuel to reach the operation temperature required. The increase of IPA concentrations in the feeds resulted in a better TOC removal. For mixtures containing acetic acid, 99% elimination of TOC was achieved at temperatures higher than 750 °C. In the case of mixtures containing ammonia, TOC removals reached 99% while maximum total nitrogen removals were never higher than 94%, even for reaction temperatures higher than 710 °C. Ignition was observed at concentrations as high as 6% wt NH(3) with 2% wt IPA while at IPA concentrations below 2% wt IPA, the ammonia did not ignite. PMID:21420141

  7. Nitrous oxide production pathways in a partial nitritation-anammox reactor: Isotopic evidence for nitrous oxide production associated anaerobic ammonium oxidation?

    NASA Astrophysics Data System (ADS)

    Wunderlin, P.; Harris, E. J.; Joss, A.; Emmenegger, L.; Kipf, M.; Mohn, J.; Siegrist, H.

    2014-12-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment N2O can be produced via several pathways. This study investigates the dynamics of N2O emissions from a nitritation-anammox reactor, and links its interpretation to the nitrogen and oxygen isotopic signature of the emitted N2O. A 400-litre single-stage nitritation-anammox reactor was operated and continuously fed with digester liquid. The isotopic composition of N2O emissions was monitored online with quantum cascade laser absorption spectroscopy (QCLAS; Aerodyne Research, Inc.; Waechter et al., 2008). Dissolved ammonium and nitrate were monitored online (ISEmax, Endress + Hauser), while nitrite was measured with test strips (Nitrite-test 0-24mgN/l, Merck). Table 1. Summary of experiments conducted to understand N2O emissions Experimental conditions O2[mgO2/L] NO2-[mgN/L] NH4+[mgN/L] N2O/NH4+[%] Normal operation <0.1 <0.5 10 0.6 Normal operation, high NH4+ <0.1 <0.5 100 6.1 High aeration 0.5 to 1.5 up to 50 10 and 50 4.9 NO2- addition (oxic) <0.1 <0.5 to 4 10 5.8 NO2- addition (anoxic) 0 <0.5 to 4 10 3.2 NH2OH addition <0.1 <0.5 10 2.5 Results showed that under normal operating conditions, the N2O isotopic site preference (SP = d15Nα - d15Nβ) was much higher than expected - up to 41‰ - strongly suggesting an unknown N2O production pathway, which is hypothesized to be mediated by anammox activity (Figure 1). A less likely explanation is that the SP of N2O was increased by partial N2O reduction by heterotrophic denitrification. Various experiments were conducted to further investigate N2O formation pathways in the reactor. Our data reveal that N2O emissions increased when reactor operation was not ideal, for example when dissolved oxygen was too high (Table 1). SP measurements confirmed that these N2O peaks were due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor (Figure 1; Table 1). Overall

  8. Active carbon-ceramic sphere as support of ruthenium catalysts for catalytic wet air oxidation (CWAO) of resin effluent.

    PubMed

    Liu, Wei-Min; Hu, Yi-Qiang; Tu, Shan-Tung

    2010-07-15

    Active carbon-ceramic sphere as support of ruthenium catalysts were evaluated through the catalytic wet air oxidation (CWAO) of resin effluent in a packed-bed reactor. Active carbon-ceramic sphere and ruthenium catalysts were characterized by N(2) adsorption and chemisorption measurements. BET surface area and total pore volume of active carbon (AC) in the active carbon-ceramic sphere increase with increasing KOH-to-carbon ratio, and AC in the sample KC-120 possesses values as high as 1100 m(2) g(-1) and 0.69 cm(3) g(-1) (carbon percentage: 4.73 wt.%), especially. Active carbon-ceramic sphere supported ruthenium catalysts were prepared using the RuCl(3) solution impregnation onto these supports, the ruthenium loading was fixed at 1-5 wt.% of AC in the support. The catalytic activity varies according to the following order: Ru/KC-120>Ru/KC-80>Ru/KC-60>KC-120>without catalysts. It is found that the 3 wt.% Ru/KC-120 catalyst displays highest stability in the CWAO of resin effluent during 30 days. Chemical oxygen demand (COD) and phenol removal were about 92% and 96%, respectively at the reaction temperature of 200 degrees C, oxygen pressure of 1.5 MPa, the water flow rate of 0.75 L h(-1) and the oxygen flow rate of 13.5 L h(-1). PMID:20362394

  9. Flow mechanism for the long-range transport of air pollutants by the sea breeze causing inland nighttime high oxidants

    SciTech Connect

    Ueda, H.; Mitsumoto, S.; Kurita, H.

    1988-02-01

    Flow mechanism causing nightttime smog was investigated by analyzing 1) continuous records of meteorological data and concentration of oxidants (Ox) for 15 days and 2) aircraft data along the transportation route of a polluted air mass.

  10. DETECTION AND MOLECULAR ANALYSIS OF PARTICULATE AIR POLLUTION INDUCED CARDIOPULMONARY OXIDATIVE STRESS USING A TRANSGENIC MOUSE MODEL AND EMERGING TECHNOLOGIES

    EPA Science Inventory


    Identification of particle characteristics and biological mechanism(s) responsible for the adverse pulmonary and cardiovascular responses associated with particulate air pollution exposure remains a critical research activity. We have employed an oxidative stress sensitive an...

  11. Planar solid oxide fuel cell with staged indirect-internal air and fuel preheating and reformation

    DOEpatents

    Geisbrecht, Rodney A; Williams, Mark C

    2003-10-21

    A solid oxide fuel cell arrangement and method of use that provides internal preheating of both fuel and air in order to maintain the optimum operating temperature for the production of energy. The internal preheat passes are created by the addition of two plates, one on either side of the bipolar plate, such that these plates create additional passes through the fuel cell. This internal preheat fuel cell configuration and method reduce the requirements for external heat exchanger units and air compressors. Air or fuel may be added to the fuel cell as required to maintain the optimum operating temperature through a cathode control valve or an anode control valve, respectively. A control loop comprises a temperature sensing means within the preheat air and fuel passes, a means to compare the measured temperature to a set point temperature and a determination based on the comparison as to whether the control valves should allow additional air or fuel into the preheat or bypass manifolds of the fuel cell.

  12. Determination of hexavalent chromium in ambient air: A story of method induced Cr(III) oxidation

    NASA Astrophysics Data System (ADS)

    Tirez, Kristof; Silversmit, Geert; Bleux, Nico; Adriaensens, Elke; Roekens, Edward; Servaes, Kelly; Vanhoof, Chris; Vincze, Laszlo; Berghmans, Patrick

    2011-09-01

    The accuracy of the determination of Cr(VI) in ambient particulate matter remains a challenge from the point of view of minimal Cr species interconversion. Knowledge of this method induced oxidation and reduction is particularly relevant for the determination of Cr(VI) in ambient particulate matter, as the level of observed Cr(III) oxidation (average of 1.7% in this study) can contribute significantly to the monitored range of measured Cr(VI) in PM 10. For Cr concentrations in PM 10 > 10 ng Cr m -3, this method induced oxidation could lead to false positive exceeding of an air quality guideline value of 0.2 ng Cr(VI) m -3 in PM 10. The median daily Cr(VI) concentration in PM 10 measured over a monitoring period of more than 2 months at two locations close to a stainless steel factory amounted to 0.9 ng Cr(VI) m -3 and 0.27 ng Cr(VI) m -3. Average daily Cr(VI)/Cr ratios in PM 10 of 3.5% and 2.6% were measured at these locations. The described monitoring for the determination of Cr(VI) in ambient air via alkaline impregnated filters is sensitive (method detection limit of 0.015 ng Cr(VI) m -3) and reproducible (precision of the method ˜25%). The average Cr(VI) recovery of 75% strongly indicates the effects of ambient sampling conditions and ambient particles on the Cr(VI) recoveries. The stability of the Cr(VI) and the Cr(III) spike on 0.12 M NaHCO 3 impregnated filters observed with XANES, indicates that the alkaline extraction of the filter in combination with the sampled air matrix is likely to induce the Cr conversions. The XANES spectra shows further that a Cr-spinel is the predominant component of Cr in ambient air PM 10 at the monitored locations.

  13. OXIDATION OF INCONEL 718 IN AIR AT TEMPERATURES FROM 973K TO 1620K.

    SciTech Connect

    GREENE,G.A.; FINFROCK,C.C.

    2000-10-01

    As part of the APT project, it was necessary to quantify the release of tungsten from the APT spallation target during postulated accident conditions in order to develop accident source terms for accident consequence characterization. Experiments with tungsten rods at high temperatures in a flowing steam environment characteristic of postulated accidents revealed that considerable vaporization of the tungsten occurred as a result of reactions with the steam and that the aerosols which formed were readily transported away from the tungsten surfaces, thus exposing fresh tungsten to react with more steam. The resulting tungsten release fractions and source terms were undesirable and it was decided to clad the tungsten target with Inconel 718 in order to protect it from contact with steam during an accident and mitigate the accident source term and the consequences. As part of the material selection criteria, experiments were conducted with Inconel 718 at high temperatures to evaluate the rate of oxidation of the proposed clad material over as wide a temperature range as possible, as well as to determine the high-temperature failure limit of the material. Samples of Inconel 718 were inserted into a preheated furnace at temperatures ranging from 973 K to 1620 K and oxidized in air for varying periods of time. After oxidizing in air at a constant temperature for the prescribed time and then being allowed to cool, the samples would be reweighed to determine their weight gain due to the uptake of oxygen. From these weight gain measurements, it was possible to identify three regimes of oxidation for Inconel 718: a low-temperature regime in which the samples became passivated after the initial oxidation, an intermediate-temperature regime in which the rate of oxidation was limited by diffusion and exhibited a constant parabolic rate dependence, and a high-temperature regime in which material deformation and damage accompanied an accelerated oxidation rate above the parabolic

  14. Anaerobic ammonium oxidation by Nitrosomonas spp. and anammox bacteria in a sequencing batch reactor.

    PubMed

    Lek Noophan, Pongsak; Sripiboon, Siriporn; Damrongsri, Mongkol; Munakata-Marr, Junko

    2009-02-01

    A sequencing batch reactor (SBR) was inoculated with mixed nitrifying bacteria from an anoxic tank at the conventional activated sludge wastewater treatment plant in Nongkhaem, Bangkok, Thailand. This enriched nitrifying culture was maintained under anaerobic conditions using ammonium (NH(4)(+)) as an electron donor and nitrite (NO(2)(-)) as an electron acceptor. Autotrophic ammonium oxidizing bacteria survived under these conditions. The enrichment period for anammox culture was over 100 days. Both ammonium and nitrite conversion rates were proportional to the biomass of ammonium oxidizing bacteria; rates were 0.08 g N/gV SS/d and 0.05 g N/g VSS/d for ammonium and nitrite, respectively, in a culture maintained for 3 months at 42 mg N/L ammonium. The nitrogen transformation rate at a ratio of NH(4)(+)-N to NO(2)(-)-N of 1:1.38 was faster, and effluent nitrogen levels were lower, than at ratios of 1:0.671, 1:2.18, and 1:3.05. Fluorescent in situ hybridization (FISH) was used to identify specific autotrophic ammonium oxidizing bacteria (Nitrosomonas spp., Candidatus Brocadia anammoxidans, and Candidatus Kuenenia stuttgartiensis). The ammonium oxidizing culture maintained at 42 mg N/L ammonium was enriched for Nitrosomonas spp. (30%) over Candidati B. anammoxidans and K. stuttgartiensis (2.1%) while the culture maintained at 210 mg N/L ammonium was dominated by Candidati B. anammoxidans and K. stuttgartiensis (85.6%). The specific nitrogen removal rate of anammox bacteria (0.6 g N/g anammox VSS/d) was significantly higher than that of ammonium oxidizing bacteria (0.4 g N/g Nitrosomonas VSS/d). Anammox bacteria removed up to 979 mg N/L/d of total nitrogen (ammonium:nitrite concentrations, 397:582 mg N/L). These results suggest significant promise of this approach for application to wastewater with high nitrogen but low carbon content, such as that found in Bangkok. PMID:18423965

  15. Simultaneous Oxidization of NOx and SO2 by a New Non-thermal Plasma Reactor Enhanced by Catalyst and Additive

    NASA Astrophysics Data System (ADS)

    Kim, Heejoon; Jun, Han; Sakaguchi, Yuhei; Minami, Wataru

    2008-02-01

    The non-thermal plasma as one of the most promising technologies for removing NOx and SO2 has attracted much attention. In this study, a new plasma reactor combined with catalyst and additive was developed to effectively oxidize and remove NOx and SO2 in the flue gas. The experimental results showed that TiO2 could improve the oxidation efficiency of SO2 in the case of applying plasma while having a negative effect on the oxidation process of NO and NOx. With the addition of NH3, the oxidation rates of NOx, NO and SO2 were slightly increased. However, the effect of adding NH3 on NOx oxidation was negative when the temperature was above 200°C.

  16. Toxicity to Daphnia magna and Vibrio fischeri of Kraft bleach plant effluents treated by catalytic wet-air oxidation.

    PubMed

    Pintar, Albin; Besson, Michèle; Gallezot, Pierre; Gibert, Janine; Martin, Dominique

    2004-01-01

    Two Kraft-pulp bleaching effluents from a sequence of treatments which include chlorine dioxide and caustic soda were treated by catalytic wet-air oxidation (CWAO) at T=463 K in trickle-bed and batch-recycle reactors packed with either TiO2 extrudates or Ru(3 wt%)/TiO2 catalyst. Chemical analyses (TOC removal, color, HPLC) and bioassays (48-h and 30-min acute toxicity tests using Daphnia magna and Vibrio fischeri, respectively) were used to get information about the toxicity impact of the starting effluents and of the treated solutions. Under the operating conditions, complex organic compounds are mostly oxidized into carbon dioxide and water, along with short-chain carboxylic acids. Bioassays were found as a complement to chemical analyses for ensuring the toxicological impact on the ecosystem. In spite of a large decrease of TOC, the solutions of end products were all more toxic to Daphnia magna than the starting effluents by factors ranging from 2 to 33. This observation is attributed to the synergistic effects of acetic acid and salts present in the solutions. On the other hand, toxicity reduction with respect to Vibrio fischeri was achieved: detoxification factors greater than unity were measured for end-product solutions treated in the presence of the Ru(3 wt%)/TiO2 catalyst, suggesting the absence of cumulative effect for this bacteria, or a lower sensitivity to the organic acids and salts. Bleach plant effluents treated by the CWAO process over the Ru/TiO2 catalyst were completely biodegradable. PMID:14675640

  17. Effect of inlet-air humidity on the formation of oxides of nitrogen in a gas-turbine combustor

    NASA Technical Reports Server (NTRS)

    Marchionna, N. R.

    1973-01-01

    Tests were conducted to determine the effect of inlet-air humidity on the formation of oxides of nitrogen from a gas-turbine combustor. Combustor inlet-air temperature ranged from 450 F to 1050 F. The tests were run at a constant pressure of 6 atmospheres and reference Mach number of 0.065. The NO sub x emission index was found to decrease with increasing inlet-air humidity at a constant exponential rate of 19 percent per mass percent water vapor in the air. This decrease of NO sub x emission index with increasing humidity was found to be independent of inlet-air temperature.

  18. Final report on international comparison CCQM-K68: Nitrous oxide in synthetic air

    NASA Astrophysics Data System (ADS)

    Lee, Jinbok; Lee, Jeongsoon; Moon, Dongmin; Seog Kim, Jin; Wessel, Rob; Aoki, Nobuyuki; Kato, Kenji; Guenther, Frank; Rhoderick, George; Konopelko, L. A.; Han, Qiao; Hall, Brad

    2011-01-01

    Nitrous oxide (N2O) is one of six greenhouse gases that are regulated by the Kyoto Protocol and has a Global Warming Potential (GWP) that is 296 times that of carbon dioxide. Global levels of nitrous oxide have increased at a rate of 0.25%/yr (0.8 ppb/yr) during the last ten years. In order to monitor levels of nitrous oxide in the atmosphere, it is necessary to use measurement standards with demonstrated equivalence at the highest level of accuracy. This report describes the results of a key comparison of standard gas mixtures of nitrous oxide in synthetic air at an amount fraction of 320 nmol/mol. This key comparison is part of the programme of the Gas Analysis Working Group (GAWG) of the CCQM to demonstrate the equivalence of the standards and measurement capabilities of the NMIs for greenhouse gases. It will support the development of measurement capability at the NMIs for nitrous oxide with uncertainties within the target set by the Global Atmospheric Watch (GAW) programme of the WMO for its global monitoring networks. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  19. High-Temperature Jet Spray Reactor for the Preparation of Rare Earth Oxides by Pyrolysis: Computer Simulation

    NASA Astrophysics Data System (ADS)

    Zhao, Qiu-yue; Lv, Chao; Zhang, Zi-mu; Dou, Zhi-he; Zhang, Ting-an; Liu, Yan; Lv, Guo-zhi

    2014-09-01

    A new type of high-temperature jet spray pyrolysis (SP) reactor is investigated in this article as part of studies on the preparation of rare earth oxides at Northeastern University (NEU), Shenyang, China. The jet spray reactor examined here is a horizontal, tubular reactor conveying the hot products of the combustion of methane and oxygen with a converging-diverging jet section in an arrangement that provides for inspiration of LaCl3 solution to pyrolyze to La2O3 with the hot gas. The present article is concerned with a computer simulation using a computational fluid dynamic model to develop the velocity, temperature, and pressure profiles in the jet reactor since direct measurement is difficult. The article includes brief comments on a room-temperature model designed to examine the flow characteristics of the jet SP reactor. It was found that the velocity decreased at first, and then it increased near the jet throat. The highest velocity occurred at the throat of jet SP reactor where the LaCl3 enters the unit. Along the reactor axis, the temperature decreases with distance from the gas inlet. The lowest temperature zone was near the wall before the throat of the reactor due to wall heat losses. The temperature was estimated to be close to 1700 K at the throat of the reactor, and it was about 1300 K toward the exit of the reactor. It was shown that a reaction would take place mainly in the throat and in the vicinity of first contact between gas and induced spray. A negative pressure was produced as gas passes through the converging-diverging throat of the jet SP reactor that causes the LaCl3 solution to enter the throat of the reactor. While the investigations of this type of reactor are at an early stage, the results look promising. NEU continues to investigate this approach for the preparation of La2O3 based on high-temperature testwork and physical modeling techniques.

  20. High-Temperature Jet Spray Reactor for the Preparation of Rare Earth Oxides by Pyrolysis: Computer Simulation

    NASA Astrophysics Data System (ADS)

    Zhao, Qiu-yue; Lv, Chao; Zhang, Zi-mu; Dou, Zhi-he; Zhang, Ting-an; Liu, Yan; Lv, Guo-zhi

    2014-08-01

    A new type of high-temperature jet spray pyrolysis (SP) reactor is investigated in this article as part of studies on the preparation of rare earth oxides at Northeastern University (NEU), Shenyang, China. The jet spray reactor examined here is a horizontal, tubular reactor conveying the hot products of the combustion of methane and oxygen with a converging-diverging jet section in an arrangement that provides for inspiration of LaCl3 solution to pyrolyze to La2O3 with the hot gas. The present article is concerned with a computer simulation using a computational fluid dynamic model to develop the velocity, temperature, and pressure profiles in the jet reactor since direct measurement is difficult. The article includes brief comments on a room-temperature model designed to examine the flow characteristics of the jet SP reactor. It was found that the velocity decreased at first, and then it increased near the jet throat. The highest velocity occurred at the throat of jet SP reactor where the LaCl3 enters the unit. Along the reactor axis, the temperature decreases with distance from the gas inlet. The lowest temperature zone was near the wall before the throat of the reactor due to wall heat losses. The temperature was estimated to be close to 1700 K at the throat of the reactor, and it was about 1300 K toward the exit of the reactor. It was shown that a reaction would take place mainly in the throat and in the vicinity of first contact between gas and induced spray. A negative pressure was produced as gas passes through the converging-diverging throat of the jet SP reactor that causes the LaCl3 solution to enter the throat of the reactor. While the investigations of this type of reactor are at an early stage, the results look promising. NEU continues to investigate this approach for the preparation of La2O3 based on high-temperature testwork and physical modeling techniques.

  1. Reactor

    DOEpatents

    Evans, Robert M.

    1976-10-05

    1. A neutronic reactor having a moderator, coolant tubes traversing the moderator from an inlet end to an outlet end, bodies of material fissionable by neutrons of thermal energy disposed within the coolant tubes, and means for circulating water through said coolant tubes characterized by the improved construction wherein the coolant tubes are constructed of aluminum having an outer diameter of 1.729 inches and a wall thickness of 0.059 inch, and the means for circulating a liquid coolant through the tubes includes a source of water at a pressure of approximately 350 pounds per square inch connected to the inlet end of the tubes, and said construction including a pressure reducing orifice disposed at the inlet ends of the tubes reducing the pressure of the water by approximately 150 pounds per square inch.

  2. Exposure to Ultrafine Particles from Ambient Air and Oxidative Stress–Induced DNA Damage

    PubMed Central

    Bräuner, Elvira Vaclavik; Forchhammer, Lykke; Møller, Peter; Simonsen, Jacob; Glasius, Marianne; Wåhlin, Peter; Raaschou-Nielsen, Ole; Loft, Steffen

    2007-01-01

    Background Particulate matter, especially ultrafine particles (UFPs), may cause health effects through generation of oxidative stress, with resulting damage to DNA and other macromolecules. Objective We investigated oxidative damage to DNA and related repair capacity in peripheral blood mononuclear cells (PBMCs) during controlled exposure to urban air particles with assignment of number concentration (NC) to four size modes with average diameters of 12, 23, 57, and 212 nm. Design Twenty-nine healthy adults participated in a randomized, two-factor cross-over study with or without biking exercise for 180 min and with exposure to particles (NC 6169-15362/cm3) or filtered air (NC 91-542/cm3) for 24 hr. Methods The levels of DNA strand breaks (SBs), oxidized purines as formamidopyrimidine DNA glycolase (FPG) sites, and activity of 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1) in PBMCs were measured by the Comet assay. mRNA levels of OGG1, nucleoside diphosphate linked moiety X-type motif 1 (NUDT1), and heme oxygenase-1 (HO1) were determined by real-time reverse transcriptase–polymerase chain reaction. Results Exposure to UFPs for 6 and 24 hr significantly increased the levels of SBs and FPG sites, with a further insignificant increase after physical exercise. The OGG1 activity and expression of OGG1, NUDT1, and HO1 were unaltered. There was a significant dose–response relationship between NC and DNA damage, with the 57-nm mode as the major contributor to effects. Concomitant exposure to ozone, nitrogen oxides, and carbon monoxide had no influence. Conclusion Our results indicate that UFPs, especially the 57-nm soot fraction from vehicle emissions, causes systemic oxidative stress with damage to DNA and no apparent compensatory up-regulation of DNA repair within 24 hr. PMID:17687444

  3. Impact of air pollution on oxidative DNA damage and lipid peroxidation in mothers and their newborns.

    PubMed

    Ambroz, Antonin; Vlkova, Veronika; Rossner, Pavel; Rossnerova, Andrea; Svecova, Vlasta; Milcova, Alena; Pulkrabova, Jana; Hajslova, Jana; Veleminsky, Milos; Solansky, Ivo; Sram, Radim J

    2016-08-01

    Ambient air particulate matter (PM) represents a class of heterogeneous substances that form one component of air pollution. Oxidative stress has been implicated as an important action mechanism for PM on the human organism. Oxidative damage induced by reactive oxygen species (ROS) may affect any cellular macromolecule. The aim of our study was to investigate the impact of air pollution on oxidative DNA damage [8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG)] and lipid peroxidation [15-F2t-isoprostane (15-F2t-IsoP)] in the urine and blood from mothers and newborns from two localities with different levels of air pollution: Ceske Budejovice (CB), a locality with a clean air, and Karvina, a locality with high air pollution. The samples from normal deliveries (38-41 week+) of nonsmoking mothers and their newborns were collected in the summer and winter seasons. Higher PM2.5 concentrations were found in Karvina than in CB in the summer 2013 (mean±SD: 20.41±6.28 vs. 9.45±3.62μg/m(3), P<0.001), and in the winter 2014 (mean±SD: 53.67±19.76 vs. 27.96±12.34μg/m(3), P<0.001). We observed significant differences in 15-F2t-IsoP levels between the summer and winter seasons in Karvina for newborns (mean±SD: 64.24±26.75 vs. 104.26±38.18pg/ml plasma, respectively) (P<0.001). Levels of 8-oxodG differed only in the winter season between localities, they were significantly higher (P<0.001) in newborns from Karvina in comparison with CB (mean±SD: 5.70±2.94 vs. 4.23±1.51 nmol/mmol creatinine, respectively). The results of multivariate regression analysis in newborns from Karvina showed PM2.5 concentrations to be a significant predictor for 8-oxodG excretion, PM2.5 and B[a]P (benzo[a]pyrene) concentrations to be a significant predictor for 15-F2t-IsoP levels. The results of multivariate regression analysis in mothers showed PM2.5 concentrations to be a significant predictor of 8-oxodG levels. PMID:27321041

  4. Airway inflammation and oxidative potential of air pollutant particles in a pediatric asthma panel

    PubMed Central

    Delfino, Ralph J.; Staimer, Norbert; Tjoa, Thomas; Gillen, Daniel L.; Schauer, James J.; Shafer, Martin M.

    2014-01-01

    Airborne particulate matter (PM) components from fossil fuel combustion can induce oxidative stress initiated by reactive oxygen species (ROS). Reported associations between worsening asthma and PM2.5 mass could be related to PM oxidative potential to induce airway oxidative stress and inflammation (hallmarks of asthma pathology). We followed 45 schoolchildren with persistent asthma in their southern California homes daily over 10 days with offline fractional exhaled nitric oxide (FENO), a biomarker of airway inflammation. Ambient exposures included daily average PM2.5, PM2.5 elemental and organic carbon (EC, OC), NO2, O3, and endotoxin. We assessed PM2.5 oxidative potential using both an abiotic and an in vitro bioassay on aqueous extracts of daily particle filters: (1) dithiothreitol (DTT) assay (abiotic), representing chemically produced ROS; and (2) ROS generated intracellularly in a rat alveolar macrophage model using the fluorescent probe 2′7′-dicholorohidroflourescin diacetate. We analyzed relations of FENO to air pollutants in mixed linear regression models. FENO was significantly positively associated with lag 1-day and 2-day averages of traffic-related markers (EC, OC, and NO2), DTT and macrophage ROS, but not PM2.5 mass. DTT associations were nearly twice as strong as other exposures per interquartile range: median FENO increased 8.7–9.9% per 0.43 nmole/min/m3 DTT. Findings suggest that future research in oxidative stress-related illnesses such as asthma and PM exposure would benefit from assessments of PM oxidative potential and composition. PMID:23673461

  5. Gas chromatograph analysis on closed air and nitrogen oxide storage atmospheres of recalcitrant seeds of Quercus Alba

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Storage of recalcitrant seeds remains an unsolved problem. This study investigated the quantitative gas analysis of nitrous oxide (N2O) and air atmospheres on the recalcitrant seeds of Quercus alba by using gas chromatograph. Ten seeds were placed in each sealed atmospheric system of air and 98/2% N...

  6. 77 FR 63827 - Request for Nominations of Experts for the Clean Air Scientific Advisory Committee (CASAC) Oxides...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-17

    ... of Nitrogen Primary National Ambient Air Quality Standards (NAAQS) Review Panel AGENCY: Environmental... the chartered CASAC on primary (human health-based) air quality standards for oxides of nitrogen (NO X... panel membership include: (a) Scientific and/or technical expertise, knowledge, and experience...

  7. Ruthenium-based electrocatalysts supported on reduced graphene oxide for lithium-air batteries.

    PubMed

    Jung, Hun-Gi; Jeong, Yo Sub; Park, Jin-Bum; Sun, Yang-Kook; Scrosati, Bruno; Lee, Yun Jung

    2013-04-23

    Ruthenium-based nanomaterials supported on reduced graphene oxide (rGO) have been investigated as air cathodes in non-aqueous electrolyte Li-air cells using a TEGDME-LiCF3SO3 electrolyte. Homogeneously distributed metallic ruthenium and hydrated ruthenium oxide (RuO2·0.64H2O), deposited exclusively on rGO, have been synthesized with average size below 2.5 nm. The synthesized hybrid materials of Ru-based nanoparticles supported on rGO efficiently functioned as electrocatalysts for Li2O2 oxidation reactions, maintaining cycling stability for 30 cycles without sign of TEGDME-LiCF3SO3 electrolyte decomposition. Specifically, RuO2·0.64H2O-rGO hybrids were superior to Ru-rGO hybrids in catalyzing the OER reaction, significantly reducing the average charge potential to ∼3.7 V at the high current density of 500 mA g(-1) and high specific capacity of 5000 mAh g(-1). PMID:23540570

  8. Mixed oxide fuels testing in the advanced test reactor to support plutonium disposition

    SciTech Connect

    Ryskamp, J.M.; Sterbentz, J.W.; Chang, G.S.

    1995-09-01

    An intense worldwide effort is now under way to find means of reducing the stockpile of weapons-grade plutonium. One of the most attractive solutions would be to use WGPu as fuel in existing light water reactors (LWRs) in the form of mixed oxide (MOX) fuel - i.e., plutonia (PUO{sub 2}) mixed with urania (UO{sub 2}). Before U.S. reactors could be used for this purpose, their operating licenses would have to be amended. Numerous technical issues must be resolved before LWR operating licenses can be amended to allow the use of MOX fuel. These issues include the following: (1) MOX fuel fabrication process verification, (2) Whether and how to use burnable poisons to depress MOX fuel initial reactivity, which is higher than that of urania, (3) The effects of WGPu isotopic composition, (4) The feasibility of loading MOX fuel with plutonia content up to 7% by weight, (5) The effects of americium and gallium in WGPu, (6) Fission gas release from MOX fuel pellets made from WGPu, (7) Fuel/cladding gap closure, (8) The effects of power cycling and off-normal events on fuel integrity, (9) Development of radial distributions of burnup and fission products, (10) Power spiking near the interfaces of MOX and urania fuel assemblies, and (11) Fuel performance code validation. We have performed calculations to show that the use of hafnium shrouds can produce spectrum adjustments that will bring the flux spectrum in ATR test loops into a good approximation to the spectrum anticipated in a commercial LWR containing MOX fuel while allowing operation of the test fuel assemblies near their optimum values of linear heat generation rate. The ATR would be a nearly ideal test bed for developing data needed to support applications to license LWRs for operation with MOX fuel made from weapons-grade plutonium. The requirements for planning and implementing a test program in the ATR have been identified.

  9. Impact of free ammonia on anammox rates (anoxic ammonium oxidation) in a moving bed biofilm reactor.

    PubMed

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2012-06-01

    Using a bench scale moving bed bioreactor (MBBR), the effect of free ammonia (FA, NH(3), the un-ionized form of ammonium NH(4)(+)) concentration on anoxic ammonium oxidation (anammox) was evaluated based on the volumetric nitrogen removal rate (NRR). Although, a detailed microbial analysis was not conducted, the major NRR observed was assumed to be by anammox, based on the nitrogen conversion ratios of nitrite to ammonium and nitrate to ammonium. Since the concentration of free ammonia as a proportion of the total ammonia concentration is pH-dependent, the impact of changing the operating pH from 6.9 to 8.2, was investigated under constant nitrogen loading conditions during continuous reactor operation. Furthermore, the effect of sudden nitrogen load changes was investigated under constant pH conditions. Batch tests were conducted to determine the immediate response of the anammox consortium to shifts in pH and FA concentrations. It was found that FA was inhibiting NRR at concentrations exceeding 2 mg N L(-1). In the pH range 7-8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 120 mg N L(-1) did not negatively affect NRR for up to 3.5 h. It was concluded that a stable NRR in a moving bed biofilm reactor depended on maintaining FA concentrations below 2 mg N L(-1) when the pH was maintained between 7 and 8. PMID:22483855

  10. Thermal-Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Air. Part I: Experiments; Part II: Separate Effects Tests and Modeling

    SciTech Connect

    Corradin, Michael; Anderson, M.; Muci, M.; Hassan, Yassin; Dominguez, A.; Tokuhiro, Akira; Hamman, K.

    2014-10-15

    This experimental study investigates the thermal hydraulic behavior and the heat removal performance for a scaled Reactor Cavity Cooling System (RCCS) with air. A quarter-scale RCCS facility was designed and built based on a full-scale General Atomics (GA) RCCS design concept for the Modular High Temperature Gas Reactor (MHTGR). The GA RCCS is a passive cooling system that draws in air to use as the cooling fluid to remove heat radiated from the reactor pressure vessel to the air-cooled riser tubes and discharged the heated air into the atmosphere. Scaling laws were used to preserve key aspects and to maintain similarity. The scaled air RCCS facility at UW-Madison is a quarter-scale reduced length experiment housing six riser ducts that represent a 9.5° sector slice of the full-scale GA air RCCS concept. Radiant heaters were used to simulate the heat radiation from the reactor pressure vessel. The maximum power that can be achieved with the radiant heaters is 40 kW with a peak heat flux of 25 kW per meter squared. The quarter-scale RCCS was run under different heat loading cases and operated successfully. Instabilities were observed in some experiments in which one of the two exhaust ducts experienced a flow reversal for a period of time. The data and analysis presented show that the RCCS has promising potential to be a decay heat removal system during an accident scenario.

  11. Microbial and Physicochemical Characteristics of Compact Anaerobic Ammonium-Oxidizing Granules in an Upflow Anaerobic Sludge Blanket Reactor

    PubMed Central

    Ni, Bing-Jie; Hu, Bao-Lan; Fang, Fang; Xie, Wen-Ming; Kartal, Boran; Liu, Xian-Wei; Sheng, Guo-Ping; Jetten, Mike; Zheng, Ping; Yu, Han-Qing

    2010-01-01

    Anaerobic ammonium oxidation (anammox) is a promising new process to treat high-strength nitrogenous wastewater. Due to the low growth rate of anaerobic ammonium-oxidizing bacteria, efficient biomass retention is essential for reactor operation. Therefore, we studied the settling ability and community composition of the anaerobic ammonium-oxidizing granules, which were cultivated in an upflow anaerobic sludge blanket (UASB) reactor seeded with aerobic granules. With this seed, the start-up period was less than 160 days at a NH4+-N removal efficiency of 94% and a loading rate of 0.064 kg N per kg volatile suspended solids per day. The formed granules were bright red and had a high settling velocity (41 to 79 m h−1). Cells and extracellular polymeric substances were evenly distributed over the anaerobic ammonium-oxidizing granules. The high percentage of anaerobic ammonium-oxidizing bacteria in the granules could be visualized by fluorescent in situ hybridization and electron microscopy. The copy numbers of 16S rRNA genes of anaerobic ammonium-oxidizing bacteria in the granules were determined to be 4.6 × 108 copies ml−1. The results of this study could be used for a better design, shorter start-up time, and more stable operation of anammox systems for the treatment of nitrogen-rich wastewaters. PMID:20190088

  12. Experience in the reprocessing of mixed-oxide fuels at PNC (Power Reactor and Nuclear Fuel Development Corporation)

    SciTech Connect

    Komatsu, Hisato; Onishi, Moichi; Araya, Sadao; Fukushima, Misao

    1989-01-01

    The Power Reactor and Nuclear Fuel Development Corporation (PNC) in Japan has experience in reprocessing mixed-oxide (MOX) fuels for the advanced thermal reactor (ATR) Fugen at the Tokai Reprocessing Plant (TRP) and for fast breeder reactors (FBRs) at the Chemical Processing Facility (CPF). The TRP was originally designed and constructed as the first reprocessing plant for light water reactor fuels in Japan. It has processed {approximately}400 t of spent fuels since 1977. To utilize recovered plutonium, PNC has developed the prototype ATR Fugen. This reactor has been operated using MOX fuel since 1978. In parallel, utilities are promoting a plutonium thermal project. Several MOX assemblies have already been loaded in a boiling water and a pressurized water reactor. To facilitate the operation of Fugen and promote research and development for the reprocessing of MOX fuels in Japan, PNC obtained a license for reprocessing fuels for Fugen at TRP in 1985. PNC has designed and constructed the CPF at Tokai Works to conduct basic research on the reprocessing of FBR fuels. The Recycle Equipment Test Facility, an engineering scale hot facility, is now being designed for further R and D in this field. It will start hot operation in the mid-1990s.

  13. Modeling of the simulated countercurrent moving-bed chromatographic reactor used for the oxidative coupling of methane

    SciTech Connect

    Tonkovich, A.L.Y.; Carr, R.W.

    1994-09-01

    The oxidative coupling reaction of methane (OCM) is a potential industrial reaction for the efficient production of ethylene. Replacement of current technologies requires significant product yield improvements. An experimental novel reactor design, the modified simulated countercurrent moving-bed chromatographic reactor (SCMCR), has reported improved ethane and ethylene product yields over other reported values. An understanding of the reactor operation is aided by concurrent mathematical modeling. The model mimics the exact experimental reactor configuration. Four sections are used; each section contains a reaction column and two separation columns connected in series. The feed is switched from section to section at discrete intervals. Reaction occurs in the first column and is followed by product and reactant separation in the ensuing section columns. Langmuir adsorption isotherms are used. The model does not incorporate the realistic and complex kinetics rising, from the OCM, rather a simplified reaction term is used to qualitatively gain insight into the operation of the modified SCMCR. A unimolecular reaction network is used in the model. The rate constants are set to permit a small fractional conversion, 5% per pass, at the concentrations during the first cycle. Similarly to the experimental reactor, the model adds a make-up feed (defined as percentage of the original feed, where excess methane is fed during the first cycle of the experimental reactor) to augment lost reactants.

  14. Study of the oxide layer formed on stainless steel exposed to boiling water reactor conditions by ion beam techniques

    NASA Astrophysics Data System (ADS)

    Degueldre, C.; Buckley, D.; Dran, J. C.; Schenker, E.

    1998-01-01

    The build-up of the oxide layer on austenitic steel under boiling water reactor (BWR) conditions was studied by macro- and micro-Rutherford backscattering spectrometry (RBS) and sputtered neutral mass spectroscopy (SNMS). RBS is applicable when the oxide thickness is larger than 20 nm and yields both the layer thickness and its stoichiometry. SNMS provides elemental depth profiles and the oxide thickness when combined with profilometry. Stainless steel strip samples pre-treated (electro- or mechanically polished) or not, exposed in a loop simulating the BWR-conditions for periods ranging from 31 to 291 days and with a low water flow velocity show oxide layers with a thickness of about 300 to 600 nm. There is no significant increase of the oxide layer thickness after 31 days of exposure. The paper confirms the presence of inner and outer oxide layers and also confirms the stoichiometry M 2O 3 in the external part in contact with the oxygenated water. The oxide layer consists not only of an outer layer and an inner layer but also of a deep apparent oxide/metal interface that is attributed to oxide formation through the steel grain boundaries.

  15. Alternative materials for solid oxide fuel cells: Factors affecting air-sintering of chromite interconnections

    SciTech Connect

    Chick, L.A.; Bates, J.L.

    1992-07-01

    The purpose of this research is to develop alternative materials for solid oxide fuel cell (SOFC) interconnections and electrodes with improved electrical, thermal and electrochemical properties. Another objective is to develop synthesis and fabrication processes for these materials whereby they can be consolidated in air into SOFCs. The approach is to (1) develop modifications of the current, state-of-the-art materials used in SOFCs, (2) minimize the number of cations used in the SOFC materials to reduce potential deleterious interactions, (3) improve thermal, electrical, and electrochemical properties, (4) develop methods to synthesize both state-of-the-art and alternative materials for the simultaneous fabrication and consolidation in air of the interconnections and electrodes with the solid electrolyte, and (5) understand electrochemical reactions at materials interfaces and the effects of component compositions and processing on those reactions.

  16. Retrieval of the Nitrous Oxide Profiles using the AIRS Data in China

    NASA Astrophysics Data System (ADS)

    Chen, L.; Ma, P.; Tao, J.; Li, X.; Zhang, Y.; Wang, Z.; Li, S.; Xiong, X.

    2014-12-01

    As an important greenhouse gas and ozone-depleting substance, the 100-year global warming potential of Nitrous Oxide (N2O) is almost 300 times higher than that of carbon dioxide. However, there are still large uncertainties about the quantitative N2O emission and its feedback to climate change due to the coarse ground-based network. This approach attempts to retrieve the N2O profiles from the Atmospheric InfraRed Sounder (AIRS) data. First, the sensitivity of atmospheric temperature and humidity profiles and surface parameters between two spectral absorption bands were simulated by using the radiative transfer model. Second, the eigenvector regression algorithm is used to construct a priori state. Third, an optimal estimate method was developed based on the band selection of N2O. Finally, we compared our retrieved AIRS profiles with HIPPO data, and analyzed the seasonal and annual N2O distribution in China from 2004 to 2013.

  17. Thin porous indium tin oxide nanoparticle films: effects of annealing in vacuum and air

    NASA Astrophysics Data System (ADS)

    Ederth, J.; Hultåker, A.; Niklasson, G. A.; Heszler, P.; van Doorn, A. R.; Jongerius, M. J.; Burgard, D.; Granqvist, C. G.

    2005-11-01

    Electrical and optical properties were investigated in porous thin films consisting of In2O3:Sn (indium tin oxide; ITO) nanoparticles. The temperature-dependent resistivity was successfully described by a fluctuation-induced tunneling model, indicating a sample morphology dominated by clusters of ITO nanoparticles separated by insulating barriers. An effective-medium model, including the effect of ionized impurity scattering, was successfully fitted to measured reflectance and transmittance. Post-deposition treatments were carried out at 773 K for 2 h in both air and vacuum. It is shown that vacuum annealing increases either the barrier width or the area between two conducting clusters in the samples and, furthermore, an extra optical absorption occurs close to the band gap. A subsequent air annealing then reduces the effect of the barriers on the electrical properties and diminishes the absorption close to the band gap.

  18. Microleakage on Class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion.

    PubMed

    Corona, Silmara Aparecida Milori; Borsatto, Maria Cristina; Rocha, Renata Andréa Salvitti de Sá; Palma-Dibb, Regina Guenka

    2005-01-01

    This in vitro study assessed the marginal microleakage on class V cavities prepared with aluminum oxide air abrasion and restored with different glass ionomer cements. The cavities were prepared on the buccal and lingual surfaces of 15 sound third molars with an air- abrasion device (Kreativ Mach 4.1; New Image) using a 27.5-microm aluminum oxide particle stream, and were assigned to 3 groups of 10 cavities each. The restorative materials were: group I, a conventional glass ionomer cement (Ketac-Fil); groups II and III, resin-modified glass ionomer cements (Vitremer R and Fuji II LC, respectively). After placement of the restorations, the teeth were stored in distilled water at 37 degrees C for 24 h, polished and then submitted to a thermocycling regimen of 500 cycles, isolated, immersed in 0.2% Rhodamine B solution for 24 h, included and serially sectioned. Microleakage was assessed by viewing the specimens under an optical microscope connected to a color video camera and a computer. The images obtained were digitized and analyzed for microleakage using software that allows for a standard quantitative assessment of dye penetration in millimeters. Statistical analysis was done using the Kruskall-Wallis and Wilcoxon tests. Means of dye penetration (%) were: occlusal - I: 25.76 +/- 34.35, II: 20.00 +/- 42.16, III: 28.25 +/- 41.67; cervical - I: 23.72 +/- 41.84; II: 44.22 +/- 49.69, III: 39.27 +/- 50.74. No statistically significant differences (p>0.05) were observed among either the glass ionomer cements or the margins. In conclusion, class V cavities restored with either conventional or resin-modified glass ionomer cements after preparation with aluminum oxide air abrasion did not show complete sealing at the enamel and dentin/cementum margins. PMID:16113931

  19. Lanthanum manganite-based air electrode for solid oxide fuel cells

    DOEpatents

    Ruka, Roswell J.; Kuo, Lewis; Li, Baozhen

    1999-01-01

    An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La.sub.w Ca.sub.x Ln.sub.y Ce.sub.z MnO.sub.3, wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics.

  20. Lanthanum manganite-based air electrode for solid oxide fuel cells

    DOEpatents

    Ruka, R.J.; Kuo, L.; Li, B.

    1999-06-29

    An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO[sub 3]. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La[sub w]Ca[sub x]Ln[sub y]Ce[sub z]MnO[sub 3], wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics. 10 figs.

  1. Incipient oxidation kinetics of alloy 617 and residual stress of the oxide scale formed in air at temperatures between 850 and 1000 °C

    NASA Astrophysics Data System (ADS)

    Tung, Hsiao-Ming; Stubbins, James F.

    2012-05-01

    The purpose of this study was to investigate incipient oxidation of alloy 617 in air in the temperature range of 850-1000 °C. Alloy 617 exhibited a two-stage oxidation kinetics and followed Wagner's parabolic law. The activation energy for the first stage and the second stage are 271.2 and 318 kJ/mol, respectively. The transition time between the two stages decreased as the oxidation temperature increased. X-ray diffraction (XRD) revealed that the oxide phase is chromium oxide, Cr2O3, over the entire temperature range. The results of residual stress measurements showed that the grown-in stresses of the scale are tensile in nature. This may be due to the crystallite coalescence during the growth of the oxide. The measured residual stress of the substrate decreases with increasing oxidation temperature which may be attributed to the formation of pores or voids within the substrate after exposure to high temperatures.

  2. Oxidation of Zircaloy Fuel Cladding in Water-Cooled Nuclear Reactors

    SciTech Connect

    Macdonald, Digby; Urquidi-Macdonald, Mirna; Chen, Yingzi; Ai, Jiahe; Park, Pilyeon; Kim, Han-Sang

    2006-12-12

    Our work involved the continued development of the theory of passivity and passivity breakdown, in the form of the Point Defect Model, with emphasis on zirconium and zirconium alloys in reactor coolant environments, the measurement of critically-important parameters, and the development of a code that can be used by reactor operators to actively manage the accumulation of corrosion damage to the fuel cladding and other components in the heat transport circuits in both BWRs and PWRs. In addition, the modified boiling crevice model has been further developed to describe the accumulation of solutes in porous deposits (CRUD) on fuel under boiling (BWRs) and nucleate boiling (PWRs) conditions, in order to accurately describe the environment that is contact with the Zircaloy cladding. In the current report, we have derived expressions for the total steady-state current density and the partial anodic and cathodic current densities to establish a deterministic basis for describing Zircaloy oxidation. The models are “deterministic” because the relevant natural laws are satisfied explicitly, most importantly the conversation of mass and charge and the equivalence of mass and charge (Faraday’s law). Cathodic reactions (oxygen reduction and hydrogen evolution) are also included in the models, because there is evidence that they control the rate of the overall passive film formation process. Under open circuit conditions, the cathodic reactions, which must occur at the same rate as the zirconium oxidation reaction, are instrumental in determining the corrosion potential and hence the thickness of the barrier and outer layers of the passive film. Controlled hydrodynamic methods have been used to measure important parameters in the modified Point Defect Model (PDM), which is now being used to describe the growth and breakdown of the passive film on zirconium and on Zircaloy fuel sheathing in BWRs and PWRs coolant environments. The modified PDMs recognize the existence of a

  3. SPONTANEOUS CATALYTIC WET AIR OXIDATION DURING PRE-TREATMENT OF HIGH-LEVEL RADIOACTIVE WASTE SLUDGE

    SciTech Connect

    Koopman, D.; Herman, C.; Pareizs, J.; Bannochie, C.; Best, D.; Bibler, N.; Fellinger, T.

    2009-10-01

    Savannah River Remediation, LLC (SRR) operates the Defense Waste Processing Facility for the U.S. Department of Energy at the Savannah River Site. This facility immobilizes high-level radioactive waste through vitrification following chemical pretreatment. Catalytic destruction of formate and oxalate ions to carbon dioxide has been observed during qualification testing of non-radioactive analog systems. Carbon dioxide production greatly exceeded hydrogen production, indicating the occurrence of a process other than the catalytic decomposition of formic acid. Statistical modeling was used to relate the new reaction chemistry to partial catalytic wet air oxidation of both formate and oxalate ions driven by the low concentrations of palladium, rhodium, and/or ruthenium in the waste. Variations in process conditions led to increases or decreases in the total oxidative destruction, as well as partially shifting the preferred species undergoing destruction from oxalate ion to formate ion.

  4. Carbon-catalyzed oxidation of SO2 by NO2 and air

    NASA Technical Reports Server (NTRS)

    Rogowski, R. S.; Schryer, D. R.; Cofer, W. R., III; Edahl, R. A., Jr.; Munavalli, S.

    1982-01-01

    A series of experiments was performed using carbon particles (commercial furnace black) as a surrogate for soot particles. Carbon particles were suspended in water, and gas mixtures were bubbled into the suspensions to observe the effect of carbon particles on the oxidation of SO2 by air and NO2. Identical gas mixtures were bubbled into a blank containing only pure water. After exposure each solution was analyzed for pH and sulfate. It was found that NO2 greatly enhances the oxidation of SO2 to sulfate in the presence of carbon particles. The amount of sulfate found in the blanks was significantly less. Under the conditions of these experiments no saturation of the reaction was observed and SO2 was converted to sulfate even in a highly acid medium (pH or = 1.5).

  5. Oxidation of SO2 by NO2 and air in an aqueous suspension of carbon

    NASA Technical Reports Server (NTRS)

    Rogowski, R. S.; Schryer, D. R.; Cofer, W. R., III; Edahl, R. A., Jr.; Munavalli, S.

    1982-01-01

    A series of experiments has been performed using carbon black as a surrogate for soot particles. Carbon black was suspended in water and gas mixtures were bubbled into the suspensions to observe the effect of carbon particles on the oxidation of SO2 by air and NO2. Identical gas mixtures were bubbled into a black containing only pure water. After exposure each solution was analyzed for pH and sulfate. It was found that NO2 greatly enhances the oxidation of SO2 to sulfate in the presence of carbon black. The amount of sulfate in the blanks was significantly less. Under the conditions of the experiments no saturation of the reaction was observed and SO2 was converted to sulfate even in a highly acid medium (pH not less than 1.5).

  6. Oxidative Nitration of Styrenes for the Recycling of Low-Concentrated Nitrogen Dioxide in Air.

    PubMed

    Hofmann, Dagmar; de Salas, Cristina; Heinrich, Markus R

    2015-09-21

    The oxidative nitration of styrenes in ethyl acetate represents a metal-free, environmentally friendly, and sustainable technique to recover even low concentrations of NO2 in air. Favorable features are that the product mixture comprising nitroalcohols, nitroketones, and nitro nitrates simplifies at lower concentrations of NO2 . Experiments in a miniplant-type 10 L wet scrubber demonstrated that the recycling technique is well applicable on larger scales at which initial NO2 concentrations of >10 000 ppm were reliably reduced to less than 40 ppm. PMID:26284827

  7. Budgets for nocturnal VOC oxidation by nitrate radicals aloft during the 2006 Texas Air Quality Study

    NASA Astrophysics Data System (ADS)

    Brown, Steven S.; Dubé, William P.; Peischl, Jeff; Ryerson, Thomas B.; Atlas, Elliot; Warneke, Carsten; de Gouw, Joost A.; Te Lintel Hekkert, Sacco; Brock, Charles A.; Flocke, Frank; Trainer, Michael; Parrish, David D.; Feshenfeld, Frederick C.; Ravishankara, A. R.

    2011-12-01

    Industrial emissions in Houston, Texas, and along the U.S. Gulf Coast are a large source of highly reactive anthropogenic volatile organic compounds (VOCs), principally alkenes, that affect air quality in that region. Nighttime oxidation by either O3 or NO3 removes these VOCs. This paper presents a regional analysis of nighttime P-3 flights during the 2006 Texas Air Quality Study (TexAQS) to quantify the loss rates and budgets for both NO3 and highly reactive VOC. Mixing ratios and production rates of NO3 were large, up to 400 parts per trillion by volume (pptv) and 1-2 parts per billion by volume (ppbv) per hour, respectively. Budgets for NO3 show that it was lost primarily to reaction with VOCs, with the sum of anthropogenic VOCs (30-54%) and isoprene (10-50%) being the largest contributors. Indirect loss of NO3 to N2O5 hydrolysis was of lesser importance (14-28%) but was the least certain due to uncertainty in the aerosol uptake coefficient for N2O5. Reaction of NO3 with peroxy radicals was a small but nonzero contribution to NO3 loss but was also uncertain because there were no direct measurements of peroxy radicals. Net VOC oxidation rates were rapid (up to 2 ppbv VOC h-1 in industrial plumes) and were dominated by NO3, which was 3-5 times more important as an oxidant than O3. Plumes of high NO3 reactivity (i.e., short steady state lifetimes, on the order of 1 min) identified the presence of concentrated emissions of highly reactive VOCs from the Houston Ship Channel (HSC), which, depending on the particular VOC, may be efficiently oxidized during overnight transport.

  8. Air oxidation of Zircaloy-4 in the 600-1000 °C temperature range: Modeling for ASTEC code application

    NASA Astrophysics Data System (ADS)

    Coindreau, O.; Duriez, C.; Ederli, S.

    2010-10-01

    Progress in the treatment of air oxidation of zirconium in severe accident (SA) codes are required for a reliable analysis of severe accidents involving air ingress. Air oxidation of zirconium can actually lead to accelerated core degradation and increased fission product release, especially for the highly-radiotoxic ruthenium. This paper presents a model to simulate air oxidation kinetics of Zircaloy-4 in the 600-1000 °C temperature range. It is based on available experimental data, including separate-effect experiments performed at IRSN and at Forschungszentrum Karlsruhe. The kinetic transition, named "breakaway", from a diffusion-controlled regime to an accelerated oxidation is taken into account in the modeling via a critical mass gain parameter. The progressive propagation of the locally initiated breakaway is modeled by a linear increase in oxidation rate with time. Finally, when breakaway propagation is completed, the oxidation rate stabilizes and the kinetics is modeled by a linear law. This new modeling is integrated in the severe accident code ASTEC, jointly developed by IRSN and GRS. Model predictions and experimental data from thermogravimetric results show good agreement for different air flow rates and for slow temperature transient conditions.

  9. Raman spectroscopy analysis of air grown oxide scale developed on pure zirconium substrate

    NASA Astrophysics Data System (ADS)

    Kurpaska, L.; Favergeon, J.; Lahoche, L.; El-Marssi, M.; Grosseau Poussard, J.-L.; Moulin, G.; Roelandt, J.-M.

    2015-11-01

    Using Raman spectroscopy technique, external and internal parts of zirconia oxide films developed at 500 °C and 600 °C on pure zirconium substrate under air at normal atmospheric pressure have been examined. Comparison of Raman peak positions of tetragonal and monoclinic zirconia phases, recorded during the oxide growth at elevated temperature, and after cooling at room temperature have been presented. Subsequently, Raman peak positions (or shifts) were interpreted in relation with the stress evolution in the growing zirconia scale, especially closed to the metal/oxide interface, where the influence of compressive stress in the oxide is the biggest. Reported results, for the first time show the presence of a continuous layer of tetragonal zirconia phase developed in the proximity of pure zirconium substrate. Based on the Raman peak positions we prove that this tetragonal layer is stabilized by the high compressive stress and sub-stoichiometry level. Presence of the tetragonal phase located in the outer part of the scale have been confirmed, yet its Raman characteristics suggest a stress-free tetragonal phase, therefore different type of stabilization mechanism. Presented study suggest that its stabilization could be related to the lattice defects introduced by highstoichiometry of zirconia or presence of heterovalent cations.

  10. Evaluation of Fe(II) oxidation at an acid mine drainage site using laboratory-scale reactors

    NASA Astrophysics Data System (ADS)

    Brown, Juliana; Burgos, William

    2010-05-01

    Acid mine drainage (AMD) is a severe environmental threat to the Appalachian region of the Eastern United States. The Susquehanna and Potomac River basins of Pennsylvania drain to the Chesapeake Bay, which is heavily polluted by acidity and metals from AMD. This study attempted to unravel the complex relationships between AMD geochemistry, microbial communities, hydrodynamic conditions, and the mineral precipitates for low-pH Fe mounds formed downstream of deep mine discharges, such as Lower Red Eyes in Somerset County, PA, USA. This site is contaminated with high concentrations of Fe (550 mg/L), Mn (115 mg/L), and other trace metals. At the site 95% of dissolved Fe(II) and 56% of total dissolved Fe is removed without treatment, across the mound, but there is no change in the concentration of trace metals. Fe(III) oxides were collected across the Red Eyes Fe mound and precipitates were analyzed by X-ray diffraction, electron microscopy and elemental analysis. Schwertmannite was the dominant mineral phase with traces of goethite. The precipitates also contained minor amounts of Al2O3, MgO,and P2O5. Laboratory flow-through reactors were constructed to quantify Fe(II) oxidation and Fe removal over time at terrace and pool depositional facies. Conditions such as residence time, number of reactors in sequence and water column height were varied to determine optimal conditions for Fe removal. Reactors with sediments collected from an upstream terrace oxidized more than 50% of dissolved Fe(II) at a ten hour residence time, while upstream pool sediments only oxidized 40% of dissolved Fe(II). Downstream terrace and pool sediments were only capable of oxidizing 25% and 20% of Fe(II), respectively. Fe(II) oxidation rates measured in the reactors were determined to be between 3.99 x 10-8and 1.94 x 10-7mol L-1s-1. The sediments were not as efficient for total dissolved Fe removal and only 25% was removed under optimal conditions. The removal efficiency for all sediments

  11. Effects of hydraulic retention time and nitrobenzene concentration on the performance of sequential upflow anaerobic filter and air lift reactors in treating nitrobenzene-containing wastewater.

    PubMed

    Wu, Jinhua; Chen, Guocai; Gu, Jingjing; Yin, Weizhao; Lu, Mengxiong; Li, Ping; Yang, Bo

    2014-11-01

    Sequential upflow anaerobic filter (UAF)/air lift (ALR) reactors were employed to investigate the effects of hydraulic retention time (HRT) and nitrobenzene (NB) concentration on treatment of NB-containing wastewater. The results showed that NB was effectively reduced to aniline (AN) with glucose as co-substrate in the UAF reactor. The AN and the remaining intermediates after the UAF reactor were then efficiently degraded in the ALR reactor. A removal efficiency of 100% and 96% was obtained for NB and chemical oxygen demand (COD), respectively, using sequential UAF/ALR reactors with an HRT of 8-72 h in the UAF reactor and 2-18 h in the ALR reactor. The corresponding optimal influent NB concentration varied between 100 and 400 mg l(-1) to achieve the optimal NB and COD removal. The NB removal efficiency decreased to 90% and to 97% if the HRT in the UAF reactor decreased from 8 to 2 h and the influent NB concentration increased from 400 to 800 mg l(-1), respectively. The results showed that sequential UAF/ALR system can be operated at low HRTs and high NB concentrations without significantly affecting the removal efficiency of NB in the reactor system. The UAF/ALR system can provide an effective yet low cost method for treatment of NB-containing industrial wastewater. PMID:24969431

  12. Composite polymer/oxide hollow fiber contactors: versatile and scalable flow reactors for heterogeneous catalytic reactions in organic synthesis.

    PubMed

    Moschetta, Eric G; Negretti, Solymar; Chepiga, Kathryn M; Brunelli, Nicholas A; Labreche, Ying; Feng, Yan; Rezaei, Fateme; Lively, Ryan P; Koros, William J; Davies, Huw M L; Jones, Christopher W

    2015-05-26

    Flexible composite polymer/oxide hollow fibers are used as flow reactors for heterogeneously catalyzed reactions in organic synthesis. The fiber synthesis allows for a variety of supported catalysts to be embedded in the walls of the fibers, thus leading to a diverse set of reactions that can be catalyzed in flow. Additionally, the fiber synthesis is scalable (e.g. several reactor beds containing many fibers in a module may be used) and thus they could potentially be used for the large-scale production of organic compounds. Incorporating heterogeneous catalysts in the walls of the fibers presents an alternative to a traditional packed-bed reactor and avoids large pressure drops, which is a crucial challenge when employing microreactors. PMID:25865826

  13. One-dimensional manganese-cobalt oxide nanofibres as bi-functional cathode catalysts for rechargeable metal-air batteries

    PubMed Central

    Jung, Kyu-Nam; Hwang, Soo Min; Park, Min-Sik; Kim, Ki Jae; Kim, Jae-Geun; Dou, Shi Xue; Kim, Jung Ho; Lee, Jong-Won

    2015-01-01

    Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type manganese-cobalt oxide nanofibres fabricated by an electrospinning technique. The spinel oxide nanofibres exhibit high catalytic activity towards both oxygen reduction and evolution in an alkaline electrolyte. When incorporated as cathode catalysts in Zn-air batteries, the fibrous spinel oxides considerably reduce the discharge-charge voltage gaps (improve the round-trip efficiency) in comparison to the catalyst-free cathode. Moreover, the nanofibre catalysts remain stable over the course of repeated discharge-charge cycling; however, carbon corrosion in the catalyst/carbon composite cathode degrades the cycling performance of the batteries. PMID:25563733

  14. One-dimensional manganese-cobalt oxide nanofibres as bi-functional cathode catalysts for rechargeable metal-air batteries.

    PubMed

    Jung, Kyu-Nam; Hwang, Soo Min; Park, Min-Sik; Kim, Ki Jae; Kim, Jae-Geun; Dou, Shi Xue; Kim, Jung Ho; Lee, Jong-Won

    2015-01-01

    Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type manganese-cobalt oxide nanofibres fabricated by an electrospinning technique. The spinel oxide nanofibres exhibit high catalytic activity towards both oxygen reduction and evolution in an alkaline electrolyte. When incorporated as cathode catalysts in Zn-air batteries, the fibrous spinel oxides considerably reduce the discharge-charge voltage gaps (improve the round-trip efficiency) in comparison to the catalyst-free cathode. Moreover, the nanofibre catalysts remain stable over the course of repeated discharge-charge cycling; however, carbon corrosion in the catalyst/carbon composite cathode degrades the cycling performance of the batteries. PMID:25563733

  15. One-dimensional manganese-cobalt oxide nanofibres as bi-functional cathode catalysts for rechargeable metal-air batteries

    NASA Astrophysics Data System (ADS)

    Jung, Kyu-Nam; Hwang, Soo Min; Park, Min-Sik; Kim, Ki Jae; Kim, Jae-Geun; Dou, Shi Xue; Kim, Jung Ho; Lee, Jong-Won

    2015-01-01

    Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type manganese-cobalt oxide nanofibres fabricated by an electrospinning technique. The spinel oxide nanofibres exhibit high catalytic activity towards both oxygen reduction and evolution in an alkaline electrolyte. When incorporated as cathode catalysts in Zn-air batteries, the fibrous spinel oxides considerably reduce the discharge-charge voltage gaps (improve the round-trip efficiency) in comparison to the catalyst-free cathode. Moreover, the nanofibre catalysts remain stable over the course of repeated discharge-charge cycling; however, carbon corrosion in the catalyst/carbon composite cathode degrades the cycling performance of the batteries.

  16. Influence of the biogas reburning for reducing nitric oxide emissions in an alundum-tube reactor

    NASA Astrophysics Data System (ADS)

    Zhao, Jie; Wang, Qingcheng; Yu, Lihui; Wu, Liyan

    2016-05-01

    The experimental study on reburning reduction reaction between biogas and NO is very important in de-NOx technology. The reburning experiments by the simulated biogas with different operation variables have been performed in an alundum-tube reactor. Results showed that the uppermost constituent in NO-reduction was CH4, H2 second, and NO-reduction by CO in biogas reburning was negligible at the same conditions. In the condition of oxygen-poor, H2 could promote CH4 oxidation and enhance the concentration of CH3 radicals, thereby increasing the reduction efficiency of NO accordingly. At the same temperature, with the increase of stoichiometric ratio, it would increase O radicals and decrease NO reduction efficiency. With the increase of reaction temperature, the reduction efficiency behaved a trend of first increased then decreased at the same stoichiometric ratio, and obtained the maximum value 51.38% at the condition of 1200 °C and λ = 0.6. Additionally, increasing the NO input concentration also could improve the reduction efficiency under the condition of fuel-rich.

  17. Hot gas cleanup for molten carbonate fuel cells. A zinc oxide reactor model, Final report

    SciTech Connect

    Steinfeld, G.

    1980-09-16

    Utilization of coal gasifiers to power MCFC requires a cleanup system to remove sulfur and particulates. Of the two near term options available for desulfurization of gasifier effluent, namely low temperature cleanup utilizing absorber/stripper technology, and hot gas cleanup utilizing metal oxides, there is a clear advantage to using hot gas cleanup. Since the MCFC will operate at 1200/sup 0/F, and the gasifier effluent could be between 1200 to 1900/sup 0/F, a hot gas cleanup system will require little or no change in process gas temperature, thereby contributing to a high overall system efficiency. A hot gas cleanup system will consist of FeO for bulk H/sub 2/S removal and ZnO for reduction of H/sub 2/S to sub ppM levels. Hot gas cleanup systems at present are not available commercially, and therefore it is the objective of this project to model the components of the system in order to help bring this technology closer to commercialization, by providing simulated operating characteristics to aid in system design, and system simulations of gasifier/MCFC systems. The modeling of the ZnO reactor is presented.

  18. Influence of the biogas reburning for reducing nitric oxide emissions in an alundum-tube reactor

    NASA Astrophysics Data System (ADS)

    Zhao, Jie; Wang, Qingcheng; Yu, Lihui; Wu, Liyan

    2016-05-01

    The experimental study on reburning reduction reaction between biogas and NO is very important in de-NOx technology. The reburning experiments by the simulated biogas with different operation variables have been performed in an alundum-tube reactor. Results showed that the uppermost constituent in NO-reduction was CH4, H2 second, and NO-reduction by CO in biogas reburning was negligible at the same conditions. In the condition of oxygen-poor, H2 could promote CH4 oxidation and enhance the concentration of CH3 radicals, thereby increasing the reduction efficiency of NO accordingly. At the same temperature, with the increase of stoichiometric ratio, it would increase O radicals and decrease NO reduction efficiency. With the increase of reaction temperature, the reduction efficiency behaved a trend of first increased then decreased at the same stoichiometric ratio, and obtained the maximum value 51.38% at the condition of 1200 °C and λ = 0.6. Additionally, increasing the NO input concentration also could improve the reduction efficiency under the condition of fuel-rich.

  19. Enhancement of the inherent self-protection of the fast sodium reactor cores with oxide fuel

    SciTech Connect

    Eliseev, V.A.; Malisheva, I.V.; Matveev, V.I.; Egorov, A.V.; Maslov, P.A.

    2013-07-01

    With the development and research into the generation IV fast sodium reactors, great attention is paid to the enhancement of the core inherent self-protection characteristics. One of the problems dealt here is connected with the reduction of the reactivity margin so that the control rods running should not result in the core overheating and melting. In this paper we consider the possibilities of improving the core of BN-1200 with oxide fuel by a known method of introducing an axial fertile layer into the core. But unlike earlier studies this paper looks at the possibility of using such a layer not only for improving breeding, but also for reducing sodium void reactivity effect (SVRE). This proposed improvement of the BN-1200 core does not solve the problem of strong interference in control and protection system (CPS) rods of BN-1200, but they reduce significantly the reactivity margin for burn-up compensation. This helps compensate all the reactivity balances in the improved core configurations without violating constraints on SVRE value.

  20. Modeling of Nitrous Oxide Production from Nitritation Reactors Treating Real Anaerobic Digestion Liquor.

    PubMed

    Wang, Qilin; Ni, Bing-Jie; Lemaire, Romain; Hao, Xiaodi; Yuan, Zhiguo

    2016-01-01

    In this work, a mathematical model including both ammonium oxidizing bacteria (AOB) and heterotrophic bacteria (HB) is constructed to predict N2O production from the nitritation systems receiving the real anaerobic digestion liquor. This is for the first time that N2O production from such systems was modeled considering both AOB and HB. The model was calibrated and validated using experimental data from both lab- and pilot-scale nitritation reactors. The model predictions matched the dynamic N2O, ammonium, nitrite and chemical oxygen demand data well, supporting the capability of the model. Modeling results indicated that HB are the dominant contributor to N2O production in the above systems with the dissolved oxygen (DO) concentration of 0.5-1.0 mg O2/L, accounting for approximately 75% of N2O production. The modeling results also suggested that the contribution of HB to N2O production decreased with the increasing DO concentrations, from 75% at DO = 0.5 mg O2/L to 25% at DO = 7.0 mg O2/L, with a corresponding increase of the AOB contribution (from 25% to 75%). Similar to HB, the total N2O production rate also decreased dramatically from 0.65 to 0.25 mg N/L/h when DO concentration increased from 0.5 to 7.0 mg O2/L. PMID:27125491

  1. Evaluation of Residence Time on Nitrogen Oxides Removal in Non-Thermal Plasma Reactor.

    PubMed

    Talebizadeh, Pouyan; Rahimzadeh, Hassan; Babaie, Meisam; Javadi Anaghizi, Saeed; Ghomi, Hamidreza; Ahmadi, Goodarz; Brown, Richard

    2015-01-01

    Non-thermal plasma (NTP) has been introduced over the last few years as a promising after- treatment system for nitrogen oxides and particulate matter removal from diesel exhaust. NTP technology has not been commercialised as yet, due to its high rate of energy consumption. Therefore, it is important to seek out new methods to improve NTP performance. Residence time is a crucial parameter in engine exhaust emissions treatment. In this paper, different electrode shapes are analysed and the corresponding residence time and NOx removal efficiency are studied. An axisymmetric laminar model is used for obtaining residence time distribution numerically using FLUENT software. If the mean residence time in a NTP plasma reactor increases, there will be a corresponding increase in the reaction time and consequently the pollutant removal efficiency increases. Three different screw thread electrodes and a rod electrode are examined. The results show the advantage of screw thread electrodes in comparison with the rod electrode. Furthermore, between the screw thread electrodes, the electrode with the thread width of 1 mm has the highest NOx removal due to higher residence time and a greater number of micro-discharges. The results show that the residence time of the screw thread electrode with a thread width of 1 mm is 21% more than for the rod electrode. PMID:26496630

  2. Evaluation of Residence Time on Nitrogen Oxides Removal in Non-Thermal Plasma Reactor

    PubMed Central

    Talebizadeh, Pouyan; Rahimzadeh, Hassan; Babaie, Meisam; Javadi Anaghizi, Saeed; Ghomi, Hamidreza; Ahmadi, Goodarz; Brown, Richard

    2015-01-01

    Non-thermal plasma (NTP) has been introduced over the last few years as a promising after- treatment system for nitrogen oxides and particulate matter removal from diesel exhaust. NTP technology has not been commercialised as yet, due to its high rate of energy consumption. Therefore, it is important to seek out new methods to improve NTP performance. Residence time is a crucial parameter in engine exhaust emissions treatment. In this paper, different electrode shapes are analysed and the corresponding residence time and NOx removal efficiency are studied. An axisymmetric laminar model is used for obtaining residence time distribution numerically using FLUENT software. If the mean residence time in a NTP plasma reactor increases, there will be a corresponding increase in the reaction time and consequently the pollutant removal efficiency increases. Three different screw thread electrodes and a rod electrode are examined. The results show the advantage of screw thread electrodes in comparison with the rod electrode. Furthermore, between the screw thread electrodes, the electrode with the thread width of 1 mm has the highest NOx removal due to higher residence time and a greater number of micro-discharges. The results show that the residence time of the screw thread electrode with a thread width of 1 mm is 21% more than for the rod electrode. PMID:26496630

  3. Modeling of Nitrous Oxide Production from Nitritation Reactors Treating Real Anaerobic Digestion Liquor

    PubMed Central

    Wang, Qilin; Ni, Bing-Jie; Lemaire, Romain; Hao, Xiaodi; Yuan, Zhiguo

    2016-01-01

    In this work, a mathematical model including both ammonium oxidizing bacteria (AOB) and heterotrophic bacteria (HB) is constructed to predict N2O production from the nitritation systems receiving the real anaerobic digestion liquor. This is for the first time that N2O production from such systems was modeled considering both AOB and HB. The model was calibrated and validated using experimental data from both lab- and pilot-scale nitritation reactors. The model predictions matched the dynamic N2O, ammonium, nitrite and chemical oxygen demand data well, supporting the capability of the model. Modeling results indicated that HB are the dominant contributor to N2O production in the above systems with the dissolved oxygen (DO) concentration of 0.5–1.0 mg O2/L, accounting for approximately 75% of N2O production. The modeling results also suggested that the contribution of HB to N2O production decreased with the increasing DO concentrations, from 75% at DO = 0.5 mg O2/L to 25% at DO = 7.0 mg O2/L, with a corresponding increase of the AOB contribution (from 25% to 75%). Similar to HB, the total N2O production rate also decreased dramatically from 0.65 to 0.25 mg N/L/h when DO concentration increased from 0.5 to 7.0 mg O2/L. PMID:27125491

  4. Fast start-up reactor for partial oxidation of methane with electrically-heated metallic monolith catalyst

    NASA Astrophysics Data System (ADS)

    Jung, Heon; Yoon, Wang Lai; Lee, Hotae; Park, Jong Soo; Shin, Jang Sik; La, Howon; Lee, Jong Dae

    A palladium-washcoated metallic monolith catalyst is applied to the partial oxidation of methane to syngas. This catalyst is highly active at a gas hourly space velocity (GHSV) of 100,000 h -1. The compact partial oxidation (POX) reactor equipped with both 96 cc of the metallic monolith catalyst and an electrically-heated catalyst (EHC) has a start-up time of less than 1.5 min and a syngas generation capacity of 9.5 Nm 3 h -1. The POX reaction is sustained without the need for an external heater. With the stand-alone POX reactor, the methane conversion can be increased either by preheating the reactant mixture heat-exchanged with the product gas, or by supplying a larger amount of oxygen than is necessary for the reaction stoichiometry.

  5. The role of intergranular chromium carbides on intergranular oxidation of nickel based alloys in pressurized water reactors primary water

    NASA Astrophysics Data System (ADS)

    Gaslain, F. O. M.; Le, H. T.; Duhamel, C.; Guerre, C.; Laghoutaris, P.

    2016-02-01

    Alloy 600 is used in pressurized water reactors (PWRs) but is susceptible to primary water stress corrosion cracking (PWSCC). Intergranular chromium carbides have been found beneficial to reduce PWSCC. Focussed ion beam coupled with scanning electron microscopy (FIB/SEM) 3D tomography has been used to reconstruct the morphology of grain boundary oxide penetrations and their interaction with intergranular Cr carbides in Alloy 600 subjected to a PWR environment. In presence of intergranular Cr carbides, the intergranular oxide penetrations are less deep but larger than without carbide. However, the intergranular oxide volumes normalized by the grain boundary length for both samples are similar, which suggest that intergranular oxidation growth rate is not affected by carbides. Analytical transmission electron microscopy (TEM) shows that the intergranular oxide consists mainly in a spinel-type oxide containing nickel and chromium, except in the vicinity of Cr carbides where Cr2O3 was evidenced. The formation of chromium oxide may explain the lower intergranular oxide depth observed in grain boundaries containing Cr carbides.

  6. A pilot study on lignocelluloses to ethanol and fish feed using NMMO pretreatment and cultivation with zygomycetes in an air-lift reactor.

    PubMed

    Lennartsson, Patrik R; Niklasson, Claes; Taherzadeh, Mohammad J

    2011-03-01

    A complete process for the production of bioethanol and fungal biomass from spruce and birch was investigated. The process included milling, pretreatment with N-methylmorpholine-N-oxide (NMMO), washing of the pretreated wood, enzymatic hydrolysis, and cultivation of the zygomycetes fungi Mucor indicus. Investigated factors included wood chip size (0.5-16 mm), pretreatment time (1-5h), and scale of the process from bench-scale to 2m high air-lift reactor. Best hydrolysis yields were achieved from wood chips below 2mm after 5h of pretreatment. Ethanol yields (mg/g wood) of 195 and 128 for spruce, and 175 and 136 for birch were achieved from bench-scale and airlift, respectively. Fungal biomass yields (mg/g wood) of 103 and 70 for spruce, and 86 and 66 for birch from bench scale and airlift respectively were simultaneously achieved. NMMO pretreatment and cultivation with M. indicus appear to be a good alternative for ethanol production from birch and spruce. PMID:21247759

  7. Dose rate estimates from irradiated light-water-reactor fuel assemblies in air

    SciTech Connect

    Lloyd, W.R.; Sheaffer, M.K.; Sutcliffe, W.G.

    1994-01-31

    It is generally considered that irradiated spent fuel is so radioactive (self-protecting) that it can only be moved and processed with specialized equipment and facilities. However, a small, possibly subnational, group acting in secret with no concern for the environment (other than the reduction of signatures) and willing to incur substantial but not lethal radiation doses, could obtain plutonium by stealing and processing irradiated spent fuel that has cooled for several years. In this paper, we estimate the dose rate at various distances and directions from typical pressurized-water reactor (PWR) and boiling-water reactor (BWR) spent-fuel assemblies as a function of cooling time. Our results show that the dose rate is reduced rapidly for the first ten years after exposure in the reactor, and that it is reduced by a factor of {approx}10 (from the one year dose rate) after 15 years. Even for fuel that has cooled for 15 years, a lethal dose (LD50) of 450 rem would be received at 1 m from the center of the fuel assembly after several minutes. However, moving from 1 to 5 m reduces the dose rate by over a factor of 10, and moving from 1 to 10 m reduces the dose rate by about a factor of 50. The dose rates 1 m from the top or bottom of the assembly are considerably less (about 10 and 22%, respectively) than 1 m from the center of the assembly, which is the direction of the maximum dose rate.

  8. Catalytic Chan–Lam coupling using a ‘tube-in-tube’ reactor to deliver molecular oxygen as an oxidant

    PubMed Central

    Mallia, Carl J; Burton, Paul M; Smith, Alexander M R; Walter, Gary C

    2016-01-01

    Summary A flow system to perform Chan–Lam coupling reactions of various amines and arylboronic acids has been realised employing molecular oxygen as an oxidant for the re-oxidation of the copper catalyst enabling a catalytic process. A tube-in-tube gas reactor has been used to simplify the delivery of the oxygen accelerating the optimisation phase and allowing easy access to elevated pressures. A small exemplification library of heteroaromatic products has been prepared and the process has been shown to be robust over extended reaction times. PMID:27559412

  9. Catalytic Chan-Lam coupling using a 'tube-in-tube' reactor to deliver molecular oxygen as an oxidant.

    PubMed

    Mallia, Carl J; Burton, Paul M; Smith, Alexander M R; Walter, Gary C; Baxendale, Ian R

    2016-01-01

    A flow system to perform Chan-Lam coupling reactions of various amines and arylboronic acids has been realised employing molecular oxygen as an oxidant for the re-oxidation of the copper catalyst enabling a catalytic process. A tube-in-tube gas reactor has been used to simplify the delivery of the oxygen accelerating the optimisation phase and allowing easy access to elevated pressures. A small exemplification library of heteroaromatic products has been prepared and the process has been shown to be robust over extended reaction times. PMID:27559412

  10. Effect of surface oxidation on the onset of nucleate boiling in a materials test reactor coolant channel

    DOE PAGESBeta

    Forrest, Eric C.; Don, Sarah M.; Hu, Lin -Wen; Buongiorno, Jacopo; McKrell, Thomas J.

    2016-02-29

    The onset of nucleate boiling (ONB) serves as the thermal-hydraulic operating limit for many research and test reactors. However, boiling incipience under forced convection has not been well-characterized in narrow channel geometries or for oxidized surface conditions. This study presents experimental data for the ONB in vertical upflow of deionized (DI) water in a simulated materials test reactor (MTR) coolant channel. The channel gap thickness and aspect ratio were 1.96 mm and 29:1, respectively. Boiling surface conditions were carefully controlled and characterized, with both heavily oxidized and native oxide surfaces tested. Measurements were performed for mass fluxes ranging from 750more » to 3000 kg/m2s and for subcoolings ranging from 10 to 45°C. ONB was identified using a combination of high-speed visual observation, surface temperature measurements, and channel pressure drop measurements. Surface temperature measurements were found to be most reliable in identifying the ONB. For the nominal (native oxide) surface, results indicate that the correlation of Bergles and Rohsenow, when paired with the appropriate single-phase heat transfer correlation, adequately predicts the ONB heat flux. Furthermore, incipience on the oxidized surface occurred at a higher heat flux and superheat than on the plain surface.« less

  11. Bioleaching of heavy metals from contaminated sediment by indigenous sulfur-oxidizing bacteria in an air-lift bioreactor: effects of sulfur concentration.

    PubMed

    Chen, Shen-Yi; Lin, Jih-Gaw

    2004-01-01

    The effects of sulfur concentration on the bioleaching of heavy metals from the sediment by indigenous sulfur-oxidizing bacteria were investigated in an air-lift reactor. Increasing the sulfur concentration from 0.5 to 5 g/l enhanced the rates of pH reduction, sulfate production and metal solubilization. A Michaelis-Menten type equation was used to explain the relationships between sulfur concentration, sulfate production and metal solubilization in the bioleaching process. After 8 days of bioleaching, 97-99% of Cu, 96-98% of Zn, 62-68% of Mn, 73-87% of Ni and 31-50% of Pb were solubilized from the sediment, respectively. The efficiency of metal solubilization was found to be related to the speciation of metal in the sediment. From economical consideration, the recommended sulfur dosage for the bioleaching of metals from the sediment is 3g/l. PMID:15276736

  12. AIR SHIPMENT OF SPENT NUCLEAR FUEL FROM THE BUDAPEST RESEARCH REACTOR

    SciTech Connect

    Dewes, J.

    2014-02-24

    The shipment of spent nuclear fuel is usually done by a combination of rail, road or sea, as the high activity of the SNF needs heavy shielding. Air shipment has advantages, e.g. it is much faster than any other shipment and therefore minimizes the transit time as well as attention of the public. Up to now only very few and very special SNF shipments were done by air, as the available container (TUK6) had a very limited capacity. Recently Sosny developed a Type C overpack, the TUK-145/C, compliant with IAEA Standard TS-R-1 for the VPVR/M type Skoda container. The TUK-145/C was first used in Vietnam in July 2013 for a single cask. In October and November 2013 a total of six casks were successfully shipped from Hungary in three air shipments using the TUK-145/C. The present paper describes the details of these shipments and formulates the lessons learned.

  13. Removal of organic pollutants from 2,2',5,5'-tetrachlorobenzidine (TCB) industrial wastewater by micro-electrochemical oxidation and air-stripping.

    PubMed

    Shibin, Xia; Shuichun, Xia; Changqing, Zhu

    2007-06-01

    A feasible method for treatment of the wastewater from the two-staged neutralization in 2,2',5,5'-tetrachlorobenzidine (TCB) manufacturing processes, a refractory dye intermediate effluents, based on combined micro-electrochemical oxidation or iron-chipping filtration (ICF) and air-stripping reactor (ASR), was developed. On conditions of HRT 1h, pH 3.0 in ICF and HRT 38 h, gas-liquid ratio 15, pH 6.0-8.65, temperature 26 degrees C in ASR, the overall COD, color, TCB and NH(4)(+)-N removal were 96.8%, 91%, 87.61% and 62%, respectively, during the treatment of TCB wastewater from the two-staged neutralization dissolved by methanol. The averaged 18.3%, 81.7% of the total degraded COD, 35.2%, 64.8% of TCB were carried out in ICF and ASR, respectively. NH(4)(+)-N removal was finished mainly in ASR. The experimental results indicated that the combined micro-electrochemical oxidation and air-stripping process performed good treatment of COD, color, TCB and NH(4)(+)-N removal in TCB wastewater from the two-staged neutralization dissolved by ethanol or acetone, came up the discharge standard in China. But the TCB wastewater from the two-staged neutralization dissolved by methanol should be deeply treated before discharged. PMID:17118553

  14. A method of examining iron oxides speciation and transport to steam generators during nuclear power reactor startups

    NASA Astrophysics Data System (ADS)

    Sawicki, Jerzy A.; Sawicka, Barbara D.; Price, James E.

    2010-12-01

    Secondary side corrosion products (sludge) collected during one of CANDU1 reactor startups from wet layup have been examined by X-ray fluorescence and Mössbauer spectroscopy. The transport and chemical form of iron oxides and oxyhydroxides were determined in condensate, feedwater and preheater outlet as a function of temperature and time. The sludge burst and oxidation states of iron oxides were correlated with the rise of reactor power and corresponding changes in temperature, condensate vacuum and water flow rate. In particular, a sharp γ-FeOOH to Fe 3O 4 switch was observed that coincided in time with the onset of condensate vacuum. Also, it was found that the startup after wet layup is characterized by only brief and fairly small sludge burst at about 30% reactor power and which contributes only a small amount of undesirable α-Fe 2O 3 to total iron transport to steam generator. Thus, sludge burden to steam generators can be minimized with proper layup and startup practices. ™ Trademark of Atomic Energy of Canada Limited.

  15. Characterization and kinetics of sulfide-oxidizing autotrophic denitrification in batch reactors containing suspended and immobilized cells.

    PubMed

    Moraes, B S; Souza, T S O; Foresti, E

    2011-01-01

    Sulfide-oxidizing autotrophic denitrification is an advantageous alternative over heterotrophic denitrification, and may have potential for nitrogen removal of low-strength wastewaters, such as anaerobically pre-treated domestic sewage. This study evaluated the fundamentals and kinetics of this process in batch reactors containing suspended and immobilized cells. Batch tests were performed for different NOx-/S2- ratios and using nitrate and nitrite as electron acceptors. Autotrophic denitrification was observed for both electron acceptors, and NOx-/S2- ratios defined whether sulfide oxidation was complete or not. Kinetic parameter values obtained for nitrate were higher than for nitrite as electron acceptor. Zero-order models were better adjusted to profiles obtained for suspended cell reactors, whereas first-order models were more adequate for immobilized cell reactors. However, in the latter, mass transfer physical phenomena had a significant effect on kinetics based on biochemical reactions. Results showed that sulfide-oxidizing autotrophic denitrification can be successfully established for low-strength wastewaters and have potential for nitrogen removal from anaerobically pre-treated domestic sewage. PMID:22097054

  16. Los Alamos Air Monitoring Data Related to the Fukushima Daiichi Reactor

    SciTech Connect

    McNaughton, Michael

    2011-01-01

    In response to the disasters in Japan on March 11, 2011, Los Alamos National Laboratory (LANL) is collecting air data and analyzing the data for fission products. At present, we report preliminary data from three high-volume air samplers and one stack sampler. Iodine-131 (I-131) is not optimally measured by our standard polypropylene filters. In addition to the filter data, we have one measurement obtained from a charcoal cartridge. These data, together with measurements of other radionuclides are adequate for a preliminary assessment and assure us that radionuclides from Fukushima Daiichi do not present a threat to human health at or near Los Alamos.

  17. Traffic-related air pollution and alveolar nitric oxide in southern California children.

    PubMed

    Eckel, Sandrah P; Zhang, Zilu; Habre, Rima; Rappaport, Edward B; Linn, William S; Berhane, Kiros; Zhang, Yue; Bastain, Theresa M; Gilliland, Frank D

    2016-05-01

    Mechanisms for the adverse respiratory effects of traffic-related air pollution (TRAP) have yet to be established. We evaluated the acute effects of TRAP exposure on proximal and distal airway inflammation by relating indoor nitric oxide (NO), a marker of TRAP exposure in the indoor microenvironment, to airway and alveolar sources of exhaled nitric oxide (FeNO).FeNO was collected online at four flow rates in 1635 schoolchildren (aged 12-15 years) in southern California (USA) breathing NO-free air. Indoor NO was sampled hourly and linearly interpolated to the time of the FeNO test. Estimated parameters quantifying airway wall diffusivity (DawNO) and flux (J'awNO) and alveolar concentration (CANO) sources of FeNO were related to exposure using linear regression to adjust for potential confounders.We found that TRAP exposure indoors was associated with elevated alveolar NO. A 10 ppb higher indoor NO concentration at the time of the FeNO test was associated with 0.10 ppb higher average CANO (95% CI 0.04-0.16) (equivalent to a 7.1% increase from the mean), 4.0% higher J'awNO (95% CI -2.8-11.3) and 0.2% lower DawNO (95% CI -4.8-4.6).These findings are consistent with an airway response to TRAP exposure that was most marked in the distal airways. PMID:26797034

  18. Oxidation, volatilization, and redistribution of molybdenum from TZM alloy in air

    SciTech Connect

    Smolik, G.R.; Petti, D.A.; McCarthy, K.A.; Schuetz, S.T.

    2000-01-01

    The excellent high temperature strength and thermal conductivity of molybdenum-base alloys provide attractive features for components in advanced magnetic and inertial fusion devices. Refractory metal alloys react readily with oxygen and other gases. Oxidized molybdenum in turn is susceptible to losses from volatile molybdenum trioxide species, MoO{sub 3}(m), in air and the hydroxide, MoO{sub 2}(OH){sub 2}, formed from water vapor. Transport of radioactivity by the volatilization, migration, and re-deposition of these volatile species during a potential accident involving a loss of vacuum or inert environment represents a safety issue. In this report the authors present experimental results on the oxidation, volatilization and re-deposition of molybdenum from TZM in flowing air between 400 and 800 C. These results are compared with calculations obtained from a vaporization mass transfer model using chemical thermodynamic data for vapor pressures of MoO{sub 3}(g) over pure solid MoO{sub 3} and an expression for the vapor pressures of MoO{sub 2}(OH){sub 2} from the literature. Calculations correlate well with experimental data.

  19. Oxidation, Volatilization, and Redistribution of Molybdenum from TZM Alloy in Air

    SciTech Connect

    Smolik, Galen Richard; Petti, David Andrew; Mccarthy, Kathryn Ann; Schuetz, Stanley Thomas

    2000-01-01

    The excellent high temperature strength and thermal conductivity of molybdenum-base alloys provide attractive features for components in advanced magnetic and inertial fusion devices. Refractory metal alloys react readily with oxygen and other gases. Oxidized molybdenum in turn is susceptible to losses from volatile molybdenum trioxide species, (MoO3)m, in air and the hydroxide, MoO2(OH)2, formed from water vapor. Transport of radioactivity by the volatilization, migration, and re-deposition of these volatile species during a potential accident involving a loss of vacuum or inert environment represents a safety issue. In this report we present experimental results on the oxidation, volatilization and re-deposition of molybdenum from TZM in flowing air between 400 and 800°C. These results are compared with calculations obtained from a vaporization mass transfer model using chemical thermodynamic data for vapor pressures of MoO3(g) over pure solid MoO3 and an expression for the vapor pressures of MoO2(OH)2 from the literature. Calculations correlate well with experimental data.

  20. Novel Molten Oxide Membrane for Ultrahigh Purity Oxygen Separation from Air.

    PubMed

    Belousov, Valery V; Kulbakin, Igor V; Fedorov, Sergey V; Klimashin, Anton A

    2016-08-31

    We present a novel solid/liquid Co3O4-36 wt % Bi2O3 composite that can be used as molten oxide membrane, MOM ( Belousov, V. V. Electrical and Mass Transport Processes in Molten Oxide Membranes. Ionics 22 , 2016 , 451 - 469 ), for ultrahigh purity oxygen separation from air. This membrane material consists of Co3O4 solid grains and intergranular liquid channels (mainly molten Bi2O3). The solid grains conduct electrons, and the intergranular liquid channels predominantly conduct oxygen ions. The liquid channels also provide the membrane material gas tightness and ductility. This last property allows us to deal successfully with the problem of thermal incompatibility. Oxygen and nitrogen permeation fluxes, oxygen ion transport number, and conductivity of the composite were measured by the gas flow, volumetric measurements of the faradaic efficiency, and four-probe dc techniques, accordingly. The membrane material showed the highest oxygen selectivity jO2/jN2 > 10(5) and sufficient oxygen permeability 2.5 × 10(-8) mol cm(-1) s(-1) at 850 °C. In the range of membrane thicknesses 1.5-3.3 mm, the oxygen permeation rate was controlled by chemical diffusion. The ease of the MOM fabrication, combined with superior oxygen selectivity and competitive oxygen permeability, shows the promise of the membrane material for ultrahigh purity oxygen separation from air. PMID:27482771

  1. Physics and thermal hydraulics design of a small water cooled reactor fuelled with plutonium in rock-like oxide (ROX) form

    SciTech Connect

    Gaultier, M.; Danguy, G.; Perry, A.; Williams, A.; Brushwood, J.; Thompson, A.; Beeley, P. A.

    2006-07-01

    This paper describes the Physics and Thermal Hydraulics areas of a design study for a small water-cooled reactor. The aim was to design a Pressurised Water Reactor (PWR) of maximum power 80 MWt, using a dispersed layout, capable of maximising primary natural circulation flow. The reactor fuel consists of plutonium contained in granular form within a Rock-like Oxide (ROX) pellet structure. (authors)

  2. Increasing the Upper Temperature Oxidation Limit of Alumina Forming Austenitic Stainless Steels in Air with Water Vapor

    SciTech Connect

    Brady, Michael P; Unocic, Kinga A; Lance, Michael J; Santella, Michael L; Yamamoto, Yukinori; Walker, Larry R

    2011-01-01

    A family of alumina-forming austenitic (AFA) stainless steels is under development for use in aggressive oxidizing conditions from {approx}600-900 C. These alloys exhibit promising mechanical properties but oxidation resistance in air with water vapor environments is currently limited to {approx}800 C due to a transition from external protective alumina scale formation to internal oxidation of aluminum with increasing temperature. The oxidation behavior of a series of AFA alloys was systematically studied as a function of Cr, Si, Al, C, and B additions in an effort to provide a basis to increase the upper-temperature oxidation limit. Oxidation exposures were conducted in air with 10% water vapor environments from 800-1000 C, with post oxidation characterization of the 900 C exposed samples by electron probe microanalysis (EPMA), scanning and transmission electron microscopy, and photo-stimulated luminescence spectroscopy (PSLS). Increased levels of Al, C, and B additions were found to increase the upper-temperature oxidation limit in air with water vapor to between 950 and 1000 C. These findings are discussed in terms of alloy microstructure and possible gettering of hydrogen from water vapor at second phase carbide and boride precipitates.

  3. Vacuum-arc chromium-based coatings for protection of zirconium alloys from the high-temperature oxidation in air

    NASA Astrophysics Data System (ADS)

    Kuprin, A. S.; Belous, V. A.; Voyevodin, V. N.; Bryk, V. V.; Vasilenko, R. L.; Ovcharenko, V. D.; Reshetnyak, E. N.; Tolmachova, G. N.; V'yugov, P. N.

    2015-10-01

    Multilayer Cr-Zr/Cr/Cr-N coatings for protection of zirconium alloys from the high-temperature oxidation in air have been obtained by the vacuum-arc evaporation technique with application of filters for plasma cleaning from macroparticles. The effect of the coatings on the corrosion resistance of zirconium alloys at test temperatures between 660 and 1100 °C for 3600 s has been investigated. The thickness, structure, phase composition, mechanical properties of the coatings and oxide layers before and after oxidation tests were examined by scanning electron microscopy, X-ray diffraction analysis and nanoindentation technique. It is shown that the hard multilayer coating effectively protects zirconium from the oxidation in air for 1 h at test temperatures. As a result of the oxidation in the coating the CrO and Cr2O3 oxides are formed which reduce the oxygen penetration through the coating. At maximum test temperature of 1100 °C the oxide layer thickness in the coating is about 5 μm. The tube shape remains unchanged independent of alloy type. It has been found that uncoated zirconium oxidizes rapidly throughout the temperature range under study. At 1100 °C a porous monoclinic ZrO2 oxide layer of ≥120 μm is formed that leads to the deformation of the samples, cracking and spalling of the oxide layer.

  4. Azo dye removal in a membrane-free up-flow biocatalyzed electrolysis reactor coupled with an aerobic bio-contact oxidation reactor.

    PubMed

    Cui, Dan; Guo, Yu-Qi; Cheng, Hao-Yi; Liang, Bin; Kong, Fan-Ying; Lee, Hyung-Sool; Wang, Ai-Jie

    2012-11-15

    Azo dyes that consist of a large quantity of dye wastewater are toxic and persistent to biodegradation, while they should be removed before being discharged to water body. In this study, Alizarin Yellow R (AYR) as a model azo dye was decolorized in a combined bio-system of membrane-free, continuous up-flow bio-catalyzed electrolysis reactor (UBER) and subsequent aerobic bio-contact oxidation reactor (ABOR). With the supply of external power source 0.5 V in the UBER, AYR decolorization efficiency increased up to 94.8±1.5%. Products formation efficiencies of p-phenylenediamine (PPD) and 5-aminosalicylic acid (5-ASA) were above 90% and 60%, respectively. Electron recovery efficiency based on AYR removal in cathode zone was nearly 100% at HRTs longer than 6 h. Relatively high concentration of AYR accumulated at higher AYR loading rates (>780 gm(-3) d(-1)) likely inhibited acetate oxidation of anode-respiring bacteria on the anode, which decreased current density in the UBER; optimal AYR loading rate for the UBER was 680 gm(-3) d(-1) (HRT 2.5 h). The subsequent ABOR further improved effluent quality. Overall the Chroma decreased from 320 times to 80 times in the combined bio-system to meet the textile wastewater discharge standard II in China. PMID:23009797

  5. Characterization study and five-cycle tests in a fixed-bed reactor of titania-supported nickel oxide as oxygen carriers for the chemical-looping combustion of methane.

    PubMed

    Corbella, Beatriz M; de Diego, Luis F; García-Labiano, Francisco; Adánez, Juan; Palaciost, José M

    2005-08-01

    Recent investigations have shown that in the combustion of carbonaceous compounds CO2 and NOx emissions to the atmosphere can be substantially reduced by using a two stage chemical-looping process. In this process, the reduction stage is undertaken in a first reactor in which the framework oxygen of a reducible inorganic oxide is used, instead of the usual atmospheric oxygen, for the combustion of a carbonaceous compound, for instance, methane. The outlet gas from this reactor is mostly composed of CO2 and steam as reaction products and further separation of these two components can be carried out easily by simple condensation of steam. Then, the oxygen carrier found in a reduced state is transported to a second reactor in which carrier regeneration with air takes place at relatively low temperatures, consequently preventing the formation of thermal NOx. Afterward, the regenerated carrier is carried to the first reactor to reinitiate a new cycle and so on for a number of repetitive cycles, while the carrier is able to withstand the severe chemical and thermal stresses involved in every cycle. In this paper, the performance of titania-supported nickel oxides has been investigated in a fixed-bed reactor as oxygen carriers for chemical-looping combustion of methane. Samples with different nickel oxide contents were prepared by successive incipient wet impregnations, and their performance as oxygen carriers was investigated at 900 degrees C and atmospheric pressure in five-cycle fixed-bed reactor tests using pure methane and pure air for the respective reduction and regeneration stages. The evolution of the outlet gas composition in each stage was followed by gas chromatography, and the involved chemical, structural, and textural changes of the carrier in the reactor bed were studied by using different characterization techniques. From the study, it is deduced that the reactivity of these nickel-based oxygen carriers is in the two involved stages and almost independent

  6. Biocatalytic desulfurization of diesel oil in an air-lift reactor with immobilized Gordonia nitida CYKS1 cells.

    PubMed

    Lee, In Su; Bae, Hee-Sung; Ryu, Hee Wook; Cho, Kyung-Suk; Chang, Yong Keun

    2005-01-01

    A new type of air-lift reactor with immobilized Gordonia nitida CYKS1 cells on a fibrous support was designed and used for the biocatalytic desulfurization (BDS) of diesel oil. Its performance was evaluated at different phase ratios of the oil to the aqueous medium (or oil phase fractions) and different sucrose concentrations. When the reaction mixture contained 10% diesel oil (v/v), 61-67% of sulfur was removed as the sulfur content decreased from 202-250 to 76-90 mg L(-1) in 72 h. The sulfur content did not decrease any further because the remaining sulfur compounds were recalcitrant to BDS. During the desulfurization, the strain CYKS1 consumed hydrocarbons in the diesel oil, mainly n-alkanes with 10-26 carbons, as carbon source even though an easily available carbon source, sucrose, was supplied. PMID:15932256

  7. Fabrication technological development of the oxide dispersion strengthened alloy MA957 for fast reactor applications

    SciTech Connect

    ML Hamilton; DS Gelles; RJ Lobsinger; GD Johnson; WF Brown; MM Paxton; RJ Puigh; CR Eiholzer; C Martinez; MA Blotter

    2000-03-27

    A significant amount of effort has been devoted to determining the properties and understanding the behavior of the alloy MA957 to define its potential usefulness as a cladding material, in the fast breeder reactor program. The numerous characterization and fabrication studies that were conducted are documented in this report. The alloy is a ferritic stainless steel developed by International Nickel Company specifically for structural reactor applications. It is strengthened by a very fine, uniformly distributed yttria dispersoid. Its fabrication involves a mechanical alloying process and subsequent extrusion, which ultimately results in a highly elongated grain structure. While the presence of the dispersoid produces a material with excellent strength, the body centered cubic structure inherent to the material coupled with the high aspect ratio that results from processing operations produces some difficulties with ductility. The alloy is very sensitive to variations in a number of processing parameters, and if the high strength is once lost during fabrication, it cannot be recovered. The microstructural evolution of the alloy under irradiation falls into two regimes. Below about 550 C, dislocation development, {alpha}{prime} precipitation and void evolution in the matrix are observed, while above about 550 C damage appears to be restricted to cavity formation within oxide particles. The thermal expansion of the alloy is very similar to that of HT9 up to the temperature where HT9 undergoes a phase transition to austenitic. Pulse magnetic welding of end caps onto MA957 tubing can be accomplished in a manner similar to that in which it is performed on HT9, although the welding parameters appear to be very sensitive to variations in the tubing that result from small changes in fabrication conditions. The tensile and stress rupture behavior of the alloy are acceptable in the unirradiated condition, being comparable to HT9 below about 700 C and exceeding those of HT9

  8. Nanoscale metal oxide and supported metal catalysts for Li-air battery

    NASA Astrophysics Data System (ADS)

    Huang, Kan

    The dissertation work focuses on research and development of durable nanoscale catalysts and supports for rechargeable Li-air batteries that use aqueous catholytes. Transition metal oxides, TiO2 and Nb2 O5 in particular, were prepared from a sol-gel process in the form of nanocoatings (5˜50 nm) on carbon nanotubes (CNTs) and studied as catalyst supports. Carbon doping in the oxides and post annealing significantly increased their electronic conductivity. Pt catalyst on the support with TiO 2 (Pt/c-TiO2/CNTs) showed a much better oxygen reduction reaction (ORR) activity than a commercial Pt on carbon black (Pt/C). Negligible loss (< 3%) in ORR activity was found in Pt/c-TiO2/CNTs as compared to more than 50% loss in Pt/C, demonstrating a significantly improved durability in the developed catalysts. However, Pt/c-Nb2O5/CNTs was found to be worse in ORR activity and durability, suggesting that c-Nb 2O5/CNTs may not be a good support. CNTs have fibrous shape and would provide a unique porous structure as electrode. Their buckypapers were made and used to support catalysts of Pt and IrO2 in the cathodes of Li-air batteries with sulfuric acid catholyte. At low Pt loading (5 wt.%) without IrO2 on the buckypaper cathode, the Li-air cell achieved a discharging capacity of 306 mAh/g and a specific energy of 1067 Wh/kg at 0.2 mA/cm2. A significant charge overpotential reduction (˜ 0.3 V) was achieved when IrO2 was also used to form a bifunctional catalyst with Pt on the buckypapers. The round trip efficiency was increased from 72% to 81% with the bifunctional cathode, demonstrating a higher energy conversion efficiency.

  9. Soil air carbon dioxide and nitrous oxide concentrations in profiles under tallgrass prairie and cultivation

    SciTech Connect

    Sotomayor, D.; Rice, C.W.

    1999-05-01

    Assessing the dynamics of gaseous production in soils is of interest because they are important sources and sinks of greenhouse gases. Changes in soil air carbon dioxide (CO{sub 2}) and nitrous oxide (N{sub 2}O) concentrations were studied in a Reading silt loam under prairie and cultivation. Concentrations were measured in situ over a 17-mo period to a depth of 3 m. Multilevel samples permitted collection of gases with subsequent measurement by gas chromatography in the laboratory. Soil air N{sub 2}O concentrations were near atmospheric levels for a majority of the study period in the prairie site but were significantly higher in the cultivated site. Annual mean N{sub 2}O concentrations were 0.403 and 1.09 {micro}L L{sup {minus}1} in the prairie and cultivated sites, respectively. Soil air CO{sub 2} annual mean concentrations were 1.56 {times} 10{sup 4} and 1.10 {times} 10{sup 4} {micro}L L{sup {minus}1} and ranged from 0.096 {times} 10{sup 4} to 6.45 {times} 10{sup 4} {micro}L L{sup {minus}1} and 0.087 {times} 10{sup 4} to 3.59 {times} 10{sup 4} {micro}L L{sup {minus}1} in the prairie and cultivated sites, respectively. Concentrations generally increased with depth, with maximum soil air N{sub 2}O and CO{sub 2} concentrations at 1.0 m in the prairie site and 0.5 m in the cultivated site. Nitrous oxide in the cultivated site and CO{sub 2} at both sites did not change markedly over winter months, but CO{sub 2} and N{sub 2}O concentrations reached maximums during the summer months and decreased as the year progressed. Although soil air concentrations peaked and decreased faster at shallower depths, deeper depths exhibited relative maximum concentrations for longer time periods.

  10. Preparation, characterization, and photocatalytic studies on anatase nano-TiO{sub 2} at internal air lift circulating photocatalytic reactor

    SciTech Connect

    Xu, Hang Li, Mei; Jun, Zhang

    2013-09-01

    Graphical abstract: The micro morphological structure of the nano-TiO{sub 2} particles was also observed with TEM, as shown in figure. The TEM images clearly exhibited the homogeneous microstructure of particles with a size of around 10–15 nm. - Highlights: • Nano-TiO{sub 2} was prepared by complex techniques of sol–gel, micro-emulsion and solvent thermal. • The size of TiO{sub 2} was nano level and uniformity. • Nano-TiO{sub 2} exhibited high photo-catalytic activity at internal air lift circulating reactor. • The best nano-TiO{sub 2} dosage was obtained. - Abstract: Anatase nano-titania (TiO{sub 2}) powder was prepared by using a sol–gel process mediated in reverse microemulsion combined with a solvent thermal technique. The structures of the obtained TiO{sub 2} were characterized by TG-DSC, XRD, TEM. The photocatalytic decomposition of methylene blue (MB) on nano-TiO{sub 2} was studied by using an internal air lift circulating photocatalytic reactor. The results show that the anatase structure appears in the calcination temperature range of 400–510 °C, while the transformation of anatase into rutile takes place above 510 °C. The homogeneous microstructure of nano-TiO{sub 2} particles was obtained with a size of around 10–15 nm. In the photocatalytic performance, degradation process follows pseudo first order kinetics with different dosages of photocatalyst and initial MB concentrations and optimal TiO{sub 2} dosage is 0.1 g/L with neutral medium.

  11. The Low Temperature Oxidation of 2,7-Dimethyloctane in a Pressurized Flow Reactor

    NASA Astrophysics Data System (ADS)

    Farid, Farinaz

    The complexity of real fuels has fostered the use of simple mixtures of hydrocarbons whose combustion behavior approximates that of real fuels in both experimental and computational studies to develop models of the combustion of the real fuel. These simple mixtures have been called surrogates. Lightly branched paraffins are an important class of constituents in gasoline, diesel and aviation turbine fuels and therefore are primary candidates for use as a component in a surrogate. Unfortunately, fundamental studies on combustion characteristics of high molecular weight mono- and di-methylated iso-paraffins are scarce. Therefore, this study was designed to investigate the low-temperature oxidation of 2,7-dimethyloctane (2,7-DMO) (C10H22), a lightly branched isomer of decane. Replicate 2,7-DMO oxidation experiments were conducted in a pressurized flow reactor (PFR) over the temperature range of 550 -- 850 K, at a pressure of 8 atm and an equivalence ratio of 0.3 in 4.21% oxygen / nitrogen. The reactivity was mapped by continuous monitoring of CO, CO 2, and O2 using a non-dispersive infrared (NDIR) carbon monoxide / carbon dioxide analyzer and an electrochemical oxygen sensor. For examining the underlying reaction chemistry, detailed speciation of samples was performed at selected temperatures using a gas chromatograph with a flame ionization detector coupled to a mass spectrometer. Comparable oxidation experiments for n-decane were carried out to examine the unique effects of branching on fuel reactivity and distribution of major stable intermediates. For both isomers, the onset of negative temperature coefficient (NTC) region was observed near 700 K, with the reactivity decreasing with increasing the temperature. The flow reactor study of n-decane oxidation confirmed that the isomerization reduces the amount of CO produced at peak reactivity. In addition to reaction inhibition, branching affected the distribution of C2-C 4 olefin intermediates. While the oxidation of

  12. Oxidation of ammonium sulfite by a multi-needle-to-plate gas phase pulsed corona discharge reactor

    NASA Astrophysics Data System (ADS)

    Ren, Hua; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

    2013-03-01

    The oxidation of ammonium sulfite in the ammonia-based flue gas desulfurization (FGD) process was investigated in a multi-needle-to-plate gas phase pulsed corona discharge reactor in this paper. The effect of several parameters, including capacitance and peak pulse voltage of discharge system, electrode gap and bubbling gas flow rate on the oxidation rate of ammonium sulfite was reviewed. The oxidation rate of ammonium sulfite could reach 47.2% at the capacitance, the peak pulse voltage, electrode gap and bubbling gas flow rate equal to 2 nF, -24.6 k V, 35 mm and 4 L min-1 within treatment time of 40 min The experimental results indicate that the gas phase pulsed discharge system with a multi-needle-to-plate electrode can oxide the ammonium sulfite. The oxidation rate increased with the applied capacitance and peak pulse voltage and decreased with the electrode gap. As the bubbling gas flow rate increased, the oxidation rate increased first and then tended to reach a stationary value. These results would be important for the process optimization of the (NH4)2SO3 to (NH4)2SO4 oxidation.

  13. Treatment of biomass gasification wastewater using a combined wet air oxidation/activated sludge process

    SciTech Connect

    English, C.J.; Petty, S.E.; Sklarew, D.S.

    1983-02-01

    A lab-scale treatability study for using thermal and biological oxidation to treat a biomass gasification wastewater (BGW) having a chemical oxygen demand (COD) of 46,000 mg/l is described. Wet air oxidation (WA0) at 300/sup 0/C and 13.8 MPa (2000 psi) was used to initially treat the BGW and resulted in a COD reduction of 74%. This was followed by conventional activated sludge treatment using operating conditions typical of municipal sewage treatment plants. This resulted in an additional 95% COD removal. Overall COD reduction for the combined process was 99%. A detailed chemical analysis of the raw BGW and thermal and biological effluents was performed using gas chromatography/mass spectrometry (GC/MS). These results showed a 97% decrease in total extractable organics with WA0 and a 99.6% decrease for combined WA0 and activated sludge treatment. Components of the treated waters tended to be fewer in number and more highly oxidized. An experiment was conducted to determine the amount of COD reduction caused by volatilization during biological treatment. Unfortunately, this did not yield conclusive results. Treatment of BGW using WA0 followed by activated sludge appears to be very effective and investigations at a larger scale are recommended.

  14. Treatment of desizing wastewater containing poly(vinyl alcohol) by wet air oxidation

    SciTech Connect

    Chen, G.; Lei, L.; Yue, P.L.; Cen, P.

    2000-05-01

    The effectiveness of wet air oxidation (WAO) is studied in a 2-L autoclave for the treatment of desizing wastewater from man-made fiber textile plants. At an oxygen pressure of less than 2 MPa, over 30-min, chemical oxygen demand (COD) removal was found to increase from 15 to 65% when the temperature was raised from 150 to 250 C. The biodegradability of the wastewater was also simultaneously increased. Up to 90% of the COD could be removed within 120 min. A simplified reaction mechanism is proposed which involves a direct mineralization step in parallel with a step in which an intermediate is formed prior to mineralization. A kinetic model for COD removal was developed based on this reaction mechanism. The model was tested with experimental COD results over the temperature range of the experiments. The dependence of the specific reaction rate constants was found to follow the Arrhenius type of equation. The direct oxidation of poly(vinyl alcohol) (PVA) to carbon dioxide and water is the dominant reaction step. The intermediates formed are not likely to be the acetic acid but may be short segments of PVA that are easily oxidized.

  15. Effect of Key Parameters on the Photocatalytic Oxidation of Toluene at Low Concentrations in Air under 254 + 185 nm UV Irradiation

    SciTech Connect

    Quici, Natalia; Vera, Maria L.; Choi, Hyeok; Puma, Gianluca Li; Dionysiou, Dionysios D.; Litter, Marta I.; Destaillats, Hugo

    2009-07-01

    The effect of key experimental parameters on the removal of toluene under 254 + 185 nm irradiation was investigated using a benchtop photocatalytic flow reactor. Toluenewas introduced at low concentrations between 10 and 500 ppbv, typical of indoorenvironments, and reacted on TiO2-coated Raschig rings. Two different TiO2-coated rings were prepared: in one case, by dip-coating using a P25 aqueous suspension and, on the other, using an organic/inorganic sol-gel method that produced thin films of mesoporous anatase. Flow rates in the photoreactor varied between 4 L min-1 and 125 mL min-1, leading to residence times in the range 100 ms< tau< 2 s. For these conditions, toluene removal efficiencies were between 30 and 90percent, indicating that the system did not achieve total conversion in any case. For each air flow rate, the conversion oftoluene was significantly higher when the reactor length was 10 cm, as compared with 5 cm; however, only marginal increases in conversions were achieved in the two reactor lengths at equal residence time and different concentration of toluene, suggesting that that the reactor is effectively behaving as an ideal reactor and that the reaction is first-order in the concentration of toluene. Experiments were carried out between 0 and 66percent relative humidity (RH), the fastest reaction rate being observed at moderately low humidity conditions (10percent RH), with respect to both dry air and higher humidity levels. Formaldehyde was formed as a partial oxidation byproduct at low and at high residence times (240 and 960 ms), although higher formaldehyde molar yields (up to 20percent) were observed at low tau (240 ms) and moderate humidity conditions (10 and 33percent), suggesting that both tau and RH can be optimized toreduce the formation of harmful intermediates. Toluene removal efficiency increased with the TiO2 thickness (i.e., mass) until a maximum value of 500 nm, beyond which the removal efficiency decreased. This should be

  16. Simplified Two-Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydorgen/Oxygen

    NASA Technical Reports Server (NTRS)

    Molnar, Melissa; Marek, C. John

    2005-01-01

    A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two-time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (> 1 x 10(exp -20) moles/cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T4). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/air fuel and for the H2/O2. A similar correlation is also developed using data from NASA s Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T4) as a function of overall fuel/air ratio, pressure and initial temperature (T3). High values of the regression coefficient R2 are obtained.

  17. Summary of Simplified Two Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydrogen/Oxygen

    NASA Technical Reports Server (NTRS)

    Marek, C. John; Molnar, Melissa

    2005-01-01

    A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (greater than l x 10(exp -20)) moles per cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T(sub 4)). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/Air fuel and for H2/O2. A similar correlation is also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T(sub 4)) as a function of overall fuel/air ratio, pressure and initial temperature (T(sub 3)). High values of the regression coefficient R squared are obtained.

  18. Development and numerical/experimental characterization of a lab-scale flat flame reactor allowing the analysis of pulverized solid fuel devolatilization and oxidation at high heating rates.

    PubMed

    Lemaire, R; Menanteau, S

    2016-01-01

    This paper deals with the thorough characterization of a new experimental test bench designed to study the devolatilization and oxidation of pulverized fuel particles in a wide range of operating conditions. This lab-scale facility is composed of a fuel feeding system, the functioning of which has been optimized by computational fluid dynamics. It allows delivering a constant and time-independent mass flow rate of fuel particles which are pneumatically transported to the central injector of a hybrid McKenna burner using a carrier gas stream that can be inert or oxidant depending on the targeted application. A premixed propane/air laminar flat flame stabilized on the porous part of the burner is used to generate the hot gases insuring the heating of the central coal/carrier-gas jet with a thermal gradient similar to those found in industrial combustors (>10(5) K/s). In the present work, results issued from numerical simulations performed a priori to characterize the velocity and temperature fields in the reaction chamber have been analyzed and confronted with experimental measurements carried out by coupling particle image velocimetry, thermocouple and two-color pyrometry measurements so as to validate the order of magnitude of the heating rate delivered by such a new test bench. Finally, the main features of the flat flame reactor we developed have been discussed with respect to those of another laboratory-scale system designed to study coal devolatilization at a high heating rate. PMID:26827350

  19. Development and numerical/experimental characterization of a lab-scale flat flame reactor allowing the analysis of pulverized solid fuel devolatilization and oxidation at high heating rates

    NASA Astrophysics Data System (ADS)

    Lemaire, R.; Menanteau, S.

    2016-01-01

    This paper deals with the thorough characterization of a new experimental test bench designed to study the devolatilization and oxidation of pulverized fuel particles in a wide range of operating conditions. This lab-scale facility is composed of a fuel feeding system, the functioning of which has been optimized by computational fluid dynamics. It allows delivering a constant and time-independent mass flow rate of fuel particles which are pneumatically transported to the central injector of a hybrid McKenna burner using a carrier gas stream that can be inert or oxidant depending on the targeted application. A premixed propane/air laminar flat flame stabilized on the porous part of the burner is used to generate the hot gases insuring the heating of the central coal/carrier-gas jet with a thermal gradient similar to those found in industrial combustors (>105 K/s). In the present work, results issued from numerical simulations performed a priori to characterize the velocity and temperature fields in the reaction chamber have been analyzed and confronted with experimental measurements carried out by coupling particle image velocimetry, thermocouple and two-color pyrometry measurements so as to validate the order of magnitude of the heating rate delivered by such a new test bench. Finally, the main features of the flat flame reactor we developed have been discussed with respect to those of another laboratory-scale system designed to study coal devolatilization at a high heating rate.

  20. FEASIBILITY ANALYSIS REPORT FOR HYBRID NON-THERMAL PLASMA REACTORS

    EPA Science Inventory

    The purpose of SERDP project CP-1038 is to evaluate and develop non-thermal plasma (NTP) reactor technology for DoD air emissions control applications. The primary focus is on oxides of nitrogen (NOx) and a secondary focus on hazardous air pollutants (HAPs), especially volatile o...

  1. Oxidation Resistance of Materials Based on Ti3AlC2 Nanolaminate at 600 °C in Air

    NASA Astrophysics Data System (ADS)

    Ivasyshyn, Andrij; Ostash, Orest; Prikhna, Tatiana; Podhurska, Viktoriya; Basyuk, Tatiana

    2016-08-01

    The oxidation behavior of Ti3AlC2-based materials had been investigated at 600 °C in static air for 1000 h. It was shown that the intense increase of weight gain per unit surface area for sintered material with porosity of 22 % attributed to oxidation of the outer surface of the specimen and surfaces of pores in the bulk material. The oxidation kinetics of the hot-pressed Ti3AlC2-based material with 1 % porosity remarkably increased for the first 15 h and then slowly decreased. The weight gain per unit surface area for this material was 1.0 mg/cm2 after exposition for 1000 h. The intense initial oxidation of Ti3AlC2-based materials can be eliminated by pre-oxidation treatment at 1200 °C in air for 2 h. As a result, the weight gain per unit surface area for the pre-oxidized material did not exceed 0.11 mg/cm2 after 1000 h of exposition at 600 °C in air. It was demonstrated that the oxidation resistance of Ti3AlC2-based materials can be significantly improved by niobium addition.

  2. CFD analyses of natural circulation in the air-cooled reactor cavity cooling system

    SciTech Connect

    Hu, R.; Pointer, W. D.

    2013-07-01

    The Natural Convection Shutdown Heat Removal Test Facility (NSTF) is currently being built at Argonne National Laboratory, to evaluate the feasibility of the passive Reactor Cavity Cooling System (RCCS) for Next Generation Nuclear Plant (NGNP). CFD simulations have been applied to evaluate the NSTF and NGNP RCCS designs. However, previous simulations found that convergence was very difficult to achieve in simulating the complex natural circulation. To resolve the convergence issue and increase the confidence of the CFD simulation results, additional CFD simulations were conducted using a more detailed mesh and a different solution scheme. It is found that, with the use of coupled flow and coupled energy models, the convergence can be greatly improved. Furthermore, the effects of convection in the cavity and the effects of the uncertainty in solid surface emissivity are also investigated. (authors)

  3. High temperature silver-palladium-copper oxide air braze filler metal

    NASA Astrophysics Data System (ADS)

    Darsell, Jens Tommy

    The Ag-CuO system is currently being investigated as the basis for an air braze filler metal alloy to be used in SOFC components. The system is of interest because unlike most braze alloys, it is capable of wetting a variety of ceramic materials while being applied in an air. This thesis work examined modification of Ag-CuO filler metal system by alloying with palladium to increase the use temperature of the resulting air braze alloy. Thermal analysis was performed to track changes in the solidus and liquidus temperatures for these alloys and determine equilibrium phase present as a function of temperature and composition. Sessile drop experiments were performed to investigate the effect of palladium addition on braze wetability. The influence of copper-oxide and palladium contents on brazed joint strength was characterized by a combination of four-point bend testing and fractography. From combined thermal analysis and quenched data it was found that both the liquidus and solidus increase with increasing palladium content, and the silver-rich miscibility gap boundary could be shifted by the addition of palladium. This was employed as a tool to study the effects of two-liquid phase formation on wetting behavior. In addition, a mass loss likely attributable to silver volatilization is observed in the Pd-modified filler metals when heated over ˜1100°C. As volatilization should be avoided, the ternary alloys should be limited to 15mol% Pd. It was found by sessile drop wetting experiments that there is a definitive change in wetting behavior that corresponds directly to the miscibility gap boundary for the Pd-Ag-CuO system. The first order transition tracks with changes in the miscibility gap boundary that can be induced by increasing palladium content. This is the first experimental evidence of critical point wetting behavior reported for a metal-oxide system and further confirms that critical point wetting theory is universal. Four-point bend testing and

  4. A method for growing a biofilm under low shear at the air-liquid interface using the drip flow biofilm reactor.

    PubMed

    Goeres, Darla M; Hamilton, Martin A; Beck, Nicholas A; Buckingham-Meyer, Kelli; Hilyard, Jackie D; Loetterle, Linda R; Lorenz, Lindsey A; Walker, Diane K; Stewart, Philip S

    2009-01-01

    This protocol describes how to grow a Pseudomonas aeruginosa biofilm under low fluid shear close to the air-liquid interface using the drip flow reactor (DFR). The DFR can model environments such as food-processing conveyor belts, catheters, lungs with cystic fibrosis and the oral cavity. The biofilm is established by operating the reactor in batch mode for 6 h. A mature biofilm forms as the reactor operates for an additional 48 h with a continuous flow of nutrients. During continuous flow, the biofilm experiences a low shear as the media drips onto a surface set at a 10 degrees angle. At the end of 54 h, biofilm accumulation is quantified by removing coupons from the reactor channels, rinsing the coupons to remove planktonic cells, scraping the biofilm from the coupon surface, disaggregating the clumps, then diluting and plating for viable cell enumeration. The entire procedure takes 13 h of active time that is distributed over 5 d. PMID:19528953

  5. Decomposition of nitric oxide in a hot nitrogen stream to synthesize air for hypersonic wind tunnel combustion testing

    NASA Technical Reports Server (NTRS)

    Zumdieck, J. F.; Zlatarich, S. A.

    1974-01-01

    A clean source of high enthalpy air was obtained from the exothermic decomposition of nitric oxide in the presence of strongly heated nitrogen. A nitric oxide jet was introduced into a confined coaxial nitrogen stream. Measurements were made of the extent of mixing and reaction. Experimental results are compared with one- and two-dimensional chemical kinetics computations. Both analyses predict much lower reactivity than was observed experimentally. Inlet nitrogen temperatures above 2400 K were sufficient to produce experimentally a completely reacted gas stream of synthetic air.

  6. The NASA Lightning Nitrogen Oxides Model (LNOM): Application to Air Quality Modeling

    NASA Technical Reports Server (NTRS)

    Koshak, William; Peterson, Harold; Khan, Maudood; Biazar, Arastoo; Wang, Lihua

    2011-01-01

    Recent improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are discussed. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(TradeMark)(NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NO(x) (= NO + NO2). The latest LNOM estimates of lightning channel length distributions, lightning 1-m segment altitude distributions, and the vertical profile of lightning NO(x) are presented. The primary improvement to the LNOM is the inclusion of non-return stroke lightning NOx production due to: (1) hot core stepped and dart leaders, (2) stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NO(x) for an August 2006 run of CMAQ is discussed.

  7. Wear and friction of oxidation-resistant mechanical carbon graphites at 650 C in air

    NASA Technical Reports Server (NTRS)

    Allen, G. P.; Wisnader, D. W.

    1975-01-01

    Studies were conducted to determine the friction and wear properties of experimental carbon-graphites. Hemispherically tipped carbon-graphite rider specimens were tested in sliding contact with rotating Inconel X-750 disks in air. A surface speed of 1.33 m/sec, a load of 500 g, and a specimen temperature of 650 C were used. Results indicate: (1) hardness is not a major factor in determining friction and wear under the conditions of these studies. (2) Friction and wear as low as or lower than those observed for a good commercial seal material were attained with some of the experimental materials studied. (3) The inclusion of boron carbide (as an oxidation inhibitor) has a strong influence on wear rate. (4) Phosphate treatment reduces the friction coefficient when boron carbide is not present in the base material.

  8. Investigation of hydrogen-air ignition sensitized by nitric oxide and by nitrogen dioxide

    NASA Technical Reports Server (NTRS)

    Slack, M.; Grillo, A.

    1977-01-01

    The sensitization of stoichiometric hydrogen-air ignition by NO, NO2 and a mixture of NO and NO2 was investigated behind reflected shock waves in a shock tube. Induction times were measured in pressure range 0.27 to 2.0 atm, temperature range 800 to 1500 K, and for NO or NO2 mole percent between 0.0 and 4.5. Addition of both NO and NO2 reduced the measured induction times. The experimental data are interpreted in terms of H2-O2-NO(x) oxidation reaction mechanisms. The influence of NO(x) upon a supersonic combustion ramjet combustor test, conducted in an arc-heated facility, is assessed.

  9. Homogeneous catalytic wet-air oxidation for the treatment of textile wastewater

    SciTech Connect

    Lei, L. Chen, G.; Hu, X.; Yue, P.L.

    2000-04-01

    An extensive series of experiments was performed to identify suitable catalysts to increase the reaction rate of wet-air oxidation of textile wastewater t relatively mild temperatures an pressures. Wastewater types treated included natural-fiber desizing wastewater, synthetic-fiber desizing wastewater, and printing and dyeing wastewater. Experimental results indicated that all catalysts tested in this investigation significantly increased the chemical oxygen demand (COD) and total organic carbon (TOC) removal rates and total COD and TOC removals. Of all catalysts tested, copper salts were the most effective. Anions in the slat solutions played a role in the catalytic process. Nitrate ions were more effective than sulfate ions. Similarly, copper nitrates were more effective than copper sulfates. A mixture of salts containing different metals performed better than any single salt.

  10. Performance of a pilot-scale packed bed reactor for perchlorate reduction using a sulfur oxidizing bacterial consortium.

    PubMed

    Boles, Amber R; Conneely, Teresa; McKeever, Robert; Nixon, Paul; Nüsslein, Klaus R; Ergas, Sarina J

    2012-03-01

    A novel sulfur-utilizing perchlorate reducing bacterial consortium successfully treated perchlorate (ClO₄⁻) in prior batch and bench-scale packed bed reactor (PBR) studies. This study examined the scale up of this process for treatment of water from a ClO ₄⁻ and RDX contaminated aquifer in Cape Cod Massachusetts. A pilot-scale upflow PBR (∼250-L) was constructed with elemental sulfur and crushed oyster shell packing media. The reactor was inoculated with sulfur oxidizing ClO₄⁻ reducing cultures enriched from a wastewater seed. Sodium sulfite provided a good method of dissolved oxygen removal in batch cultures, but was found to promote the growth of bacteria that carry out sulfur disproportionation and sulfate reduction, which inhibited ClO₄⁻ reduction in the pilot system. After terminating sulfite addition, the PBR successfully removed 96% of the influent ClO₄⁻ in the groundwater at an empty bed contact time (EBCT) of 12 h (effluent ClO₄⁻ of 4.2 µg L(-1)). Simultaneous ClO₄⁻ and NO₃⁻ reduction was observed in the lower half of the reactor before reactions shifted to sulfur disproportionation and sulfate reduction. Analyses of water quality profiles were supported by molecular analysis, which showed distinct groupings of ClO₄⁻ and NO₃⁻ degrading organisms at the inlet of the PBR, while sulfur disproportionation was the primary biological process occurring in the top potion of the reactor. PMID:22015922

  11. Air/water oxidative desulfurization of coal and sulfur-containing compounds

    NASA Astrophysics Data System (ADS)

    Warzinski, R. P.; Freidman, S.; LaCount, R. B.

    1981-02-01

    Air/water Oxydesulfurization has been demonstrated in autoclave experiments at the Pittsburgh Energy Technology Center for various coals representative of the major U. S. coal basins. The applicability at present of this treatment for producing an environmentally acceptable coal has been restricted by recently proposed SO2 emission standards for utility boilers. The product would, however, be attractive to the many smaller industrial coal users who cannot afford to operate and maintain flue gas desulfurization systems. It is also possible that the utility industry could realize a benefit by using chemically cleaned coal with partial flue gas scrubbing. The higher cost of the cleaned coal would be offset by the reduction in capital and operating costs resulting from decreased FGD requirements. The susceptibility of sulfur in coal to oxidative removal varies with the nature of the sulfur-containing species. The inorganic sulfur compounds, primarily pyrite, marcasite, and iron sulfate, are more amenable to treatment than the organically bound sulfur which exhibits varying degrees of resistance depending on its chemical environment. Air/water Oxydesulfurization consistently removes in excess of 90 percent of the pyritic sulfur; the extent and efficiency of organic sulfur removal however, depends on the type of coal and severity of treatment used. In general, the organic sulfur of the higher rank coals exhibits more resistance to treatment than that of the lower rank coals; however, the accompanying heating value is greater for the latter. Similar treatment of sulfur-containing model compounds further illustrates the relative susceptibilities of different chemical species to oxidation. Application of these data to the understanding of the complex chemistry involved in the treatment of coal is a preliminary step toward improving the efficiency of Oxydesulfurization.

  12. Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal.

    PubMed

    Makwana, J P; Joshi, Asim Kumar; Athawale, Gaurav; Singh, Dharminder; Mohanty, Pravakar

    2015-02-01

    An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210 mm diameter and 1600 mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750-850 °C, 25-31.3 kg/h, and 0.3-0.38, respectively. Flow rate of air was kept constant (37 m(3)/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ∼45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field. PMID:25446789

  13. Nitrous oxide supersaturation at the liquid/air interface of animal waste.

    PubMed

    Makris, Konstantinos C; Andra, Syam S; Hardy, Michael; Sarkar, Dibyendu; Datta, Rupali; Bach, Stephan B H; Mullens, Conor P

    2009-12-01

    Concentrated animal feeding operations around the globe generate large amounts of nitrous oxide (N(2)O) in the surrounding atmosphere. Liquid animal waste systems have received little attention with respect to N(2)O emissions. We hypothesized that the solution chemistry of animal waste aqueous suspensions would promote conditions that lead to N(2)O supersaturation at the liquid/air interface. The concentration of dissolved N(2)O in poultry litter (PL) aqueous suspensions at 25 degrees C was 0.36 microg N(2)O mL(-1), at least an order of magnitude greater than that measured in water in equilibrium with ambient air, suggesting N(2)O supersaturation. There was a nonlinear increase in the N(2)O Henry constants of PL from 2810 atm/mole fraction at 35 degrees C to 17 300 atm/mole fraction at 41 degrees C. The extremely high N(2)O Henry constants were partially ascribed to N(2)O complexation with aromatic moieties. Complexed N(2)O structures were unstable at temperatures > 35 degrees C, supplying the headspace with additional free N(2)O concentrations. PMID:19573962

  14. A new class of solid oxide metal-air redox batteries for advanced stationary energy storage

    NASA Astrophysics Data System (ADS)

    Zhao, Xuan

    Cost-effective and large-scale energy storage technologies are a key enabler of grid modernization. Among energy storage technologies currently being researched, developed and deployed, rechargeable batteries are unique and important that can offer a myriad of advantages over the conventional large scale siting- and geography- constrained pumped-hydro and compressed-air energy storage systems. However, current rechargeable batteries still need many breakthroughs in material optimization and system design to become commercially viable for stationary energy storage. This PhD research project investigates the energy storage characteristics of a new class of rechargeable solid oxide metal-air redox batteries (SOMARBs) that combines a regenerative solid oxide fuel cell (RSOFC) and hydrogen chemical-looping component. The RSOFC serves as the "electrical functioning unit", alternating between the fuel cell and electrolysis mode to realize discharge and charge cycles, respectively, while the hydrogen chemical-looping component functions as an energy storage unit (ESU), performing electrical-chemical energy conversion in situ via a H2/H2O-mediated metal/metal oxide redox reaction. One of the distinctive features of the new battery from conventional storage batteries is the ESU that is physically separated from the electrodes of RSOFC, allowing it to freely expand and contract without impacting the mechanical integrity of the entire battery structure. This feature also allows an easy switch in the chemistry of this battery. The materials selection for ESU is critical to energy capacity, round-trip efficiency and cost effectiveness of the new battery. Me-MeOx redox couples with favorable thermodynamics and kinetics are highly preferable. The preliminary theoretical analysis suggests that Fe-based redox couples can be a promising candidate for operating at both high and low temperatures. Therefore, the Fe-based redox-couple systems have been selected as the baseline for this

  15. Intrinsic catalytic properties of extruded clay honeycomb monolith toward complete oxidation of air pollutants.

    PubMed

    Assebban, Mhamed; El Kasmi, Achraf; Harti, Sanae; Chafik, Tarik

    2015-12-30

    The present work highlights the intrinsic catalytic properties of extruded clay honeycomb monolith toward complete oxidation of various air pollutants namely CO, methane, propane, acetylene, propene, n-butene, methanol, ethanol, n-propanol, n-butanol, acetone, dimethyl ether, benzene, toluene, o-xylene, monochlorobenzene and 1,2-dichlorobenzene. Total catalytic conversion was achieved for all tested compounds with different behaviors depending on pollutants' structural and chemical nature. The comparison of T50 values obtained from light-off curves allowed the establishment of the following reactivity sequence: ketone>alcohol>ether>CO>alkyne>aromatic>alkene>chlorinated aromatic>alkane. The intrinsic catalytic performances of the natural clay was ascribed to the implication of a quite complex mixture constituted by OH groups (Brønsted acids) and coordinately-unsaturated cations, such as Al(3+), Fe(3+) and Fe(2+) (Lewis acids). Hence, the combination of the clay's intrinsic catalytic performances and easier extrudability suggests a promissory potential for application in air pollution control. PMID:26259164

  16. Adaptive control of a packedbed reactor for the partial oxidation of n-butane to maleic anhydride; I. unsteady-state model and dynamics of the reactor

    SciTech Connect

    Not Available

    1984-01-01

    A nonadiabatic, fixed-bed catalytic reactor is analyzed on the basis of data for the highly exothermic partial oxidation of n-butane to maleic anhydride, in order to study multivariable adaptive control. The nonlinear partial differential equations describing the axial and radial gradients of concentration and temperature are converted into a set of nonlinear, ordinary differential and algebraic equations using orthogonal collocation, preserving the nonlinearity of the reaction term. These equations describe satisfactorily the steady state and dynamic behavior. This two-dimensional model enables the relationship between the time and temperature of reaction, and between the concentration of maleic anhydride and the hot-spot temperature to be expressed adequately by seconddegree, low-order transfer functions. This technique is applicable for any process of reaction in a packed bed.

  17. Disrupted Nitric Oxide Metabolism from Type II Diabetes and Acute Exposure to Particulate Air Pollution

    PubMed Central

    Pettit, Ashley P.; Kipen, Howard; Laumbach, Robert; Ohman-Strickland, Pamela; Kelly-McNeill, Kathleen; Cepeda, Clarimel; Fan, Zhi-Hua; Amorosa, Louis; Lubitz, Sara; Schneider, Stephen; Gow, Andrew

    2015-01-01

    Type II diabetes is an established cause of vascular impairment. Particulate air pollution is known to exacerbate cardiovascular and respiratory conditions, particularly in susceptible populations. This study set out to determine the impact of exposure to traffic pollution, with and without particle filtration, on vascular endothelial function in Type II diabetes. Endothelial production of nitric oxide (NO) has previously been linked to vascular health. Reactive hyperemia induces a significant increase in plasma nitrite, the proximal metabolite of NO, in healthy subjects, while diabetics have a lower and more variable level of response. Twenty type II diabetics and 20 controls (ages 46–70 years) were taken on a 1.5hr roadway traffic air pollution exposure as passengers. We analyzed plasma nitrite, as a measure of vascular function, using forearm ischemia to elicit a reactive hyperemic response before and after exposure to one ride with and one without filtration of the particle components of pollution. Control subjects displayed a significant increase in plasma nitrite levels during reactive hyperemia. This response was no longer present following exposure to traffic air pollution, but did not vary with whether or not the particle phase was filtered out. Diabetics did not display an increase in nitrite levels following reactive hyperemia. This response was not altered following pollution exposure. These data suggest that components of acute traffic pollution exposure diminish vascular reactivity in non-diabetic individuals. It also confirms that type II diabetics have a preexisting diminished ability to appropriately respond to a vascular challenge, and that traffic pollution exposure does not cause a further measureable acute change in plasma nitrite levels in Type II diabetics. PMID:26656561

  18. Producing nitric oxide by pulsed electrical discharge in air for portable inhalation therapy.

    PubMed

    Yu, Binglan; Muenster, Stefan; Blaesi, Aron H; Bloch, Donald B; Zapol, Warren M

    2015-07-01

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation and is an effective therapy for treating pulmonary hypertension in adults and children. In the United States, the average cost of 5 days of inhaled NO for persistent pulmonary hypertension of the newborn is about $14,000. NO therapy involves gas cylinders and distribution, a complex delivery device, gas monitoring and calibration equipment, and a trained respiratory therapy staff. The objective of this study was to develop a lightweight, portable device to serve as a simple and economical method of producing pure NO from air for bedside or portable use. Two NO generators were designed and tested: an offline NO generator and an inline NO generator placed directly within the inspiratory line. Both generators use pulsed electrical discharges to produce therapeutic range NO (5 to 80 parts per million) at gas flow rates of 0.5 to 5 liters/min. NO was produced from air, as well as gas mixtures containing up to 90% O2 and 10% N2. Potentially toxic gases produced in the plasma, including nitrogen dioxide (NO2) and ozone (O3), were removed using a calcium hydroxide scavenger. An iridium spark electrode produced the lowest ratio of NO2/NO. In lambs with acute pulmonary hypertension, breathing electrically generated NO produced pulmonary vasodilation and reduced pulmonary arterial pressure and pulmonary vascular resistance index. In conclusion, electrical plasma NO generation produces therapeutic levels of NO from air. After scavenging to remove NO2 and O3 and filtration to remove particles, electrically produced NO can provide safe and effective treatment of pulmonary hypertension. PMID:26136478

  19. Adsorption of hexavalent chromium by crosslinked chitosan-iron(III) in an air-lift reactor.

    PubMed

    Demarchi, Carla Albertina; Rodrigues, Clóvis Antonio

    2016-01-01

    Column experiments were conducted in an airlift reactor containing a certain amount of crosslinked chitosan-iron(III) (Ch-Fe), to examine the effects of adsorbent mass, flow rate, and influent concentrations on Cr(VI) removal. The breakthrough time increased with an increase in Ch-Fe mass, but decreased with an increase in initial Cr(VI) concentration. The exhaustion time decreased with an increase in initial Cr(VI) concentration. The capacity at the breakthrough point increased with an increase in Ch-Fe mass, flow rate, and initial Cr(VI) concentration. The capacity at the exhaustion point increased with an increase in flow rate, but showed no specific trend with an increase in initial Cr(VI) concentration. The bed volumes at breakthrough point increased with an increase in Ch-Fe, flow rate and Cr(VI) concentration. The adsorbent exhaustion decreased with an increase in flow rate and Ch-Fe, but increased with an increase in initial Cr(VI) concentration. Columns with large amounts of Ch-Fe are preferable for obtaining optimal results during the adsorption process. The higher the flow velocity, the better the column performance. The Thomas, Clark and Yoon-Nelson models were applied to the experimental results. Good agreement was observed between the predicted theoretical breakthrough curves and the experimental results. PMID:26901729

  20. A summary and assessment of oxidation driven volatility experiments at the INEL and their application to fusion reactor safety assessments

    SciTech Connect

    McCarthy, K.A.; Smolik, G.R.; Harms, S.L.

    1994-09-01

    This report contains a summary and assessment of oxidation-driven volatility tests through March 1994 at the Idaho National Engineering Laboratory. Materials tested include a Cu alloy in air and steam, PCA stainless steel (similar to 316SS) in air and steam, AMCR-033 steel in air, HT-9 steel in air and steam, a Nb alloy in air and steam, a W alloy in air and steam, and two V alloys in air with a limited number of tests in steam. We give a brief description of the tests, including alloy compositions and test temperatures. For many materials, our results indicate that both volatility and oxide spalling are responsible for mobilizing mass, thus we refer to our measurements as mass flux or mobility flux. We plot mobility data for each element and present curve fits to the data. We include a section on how the mobility information is used in safety assessments. We calculate the early dose inventory of a first wall made of each material tested (the early dose to the maximum exposed individual that would result if all the material were mobilized and transported to the site boundary), and the early dose that would result when mobility fractions are considered in the calculation. We use this information to assess the data by determining which elements are the most important and concentrating on providing the mobility data for those elements. We discuss where more data are needed, and our plans for obtaining that data. Additionally, we discuss what must be done to produce a database that will withstand regulatory scrutiny.