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New resistor voltage grading system at the Oak Ridge National Laboratory 25URC tandem accelerator; installation and first experience

Description: On June 27,1994, installation work was completed on a new resistor-based voltage grading system for the Holifield facility tandem accelerator. This new system replaces the original point-plane corona-discharge system which had inherent disadvantages. Perhaps the worst disadvantages of corona-discharge systems are poor gap-to-gap voltage homogeneity and very low grading currents. It is believed that the resistor-based system will reduce or eliminate these disadvantages as well as some others.
Date: December 31, 1994
Creator: Meigs, M.J.; Haynes, D.L.; Jones, C.M. & Juras, R.C.
Partner: UNT Libraries Government Documents Department

Nonthermal plasma technology for organic destruction

Description: Pacific Northwest Laboratory (PNL) is investigating the use of nonthermal, electrically driven plasmas for destroying organic contaminants near ambient temperatures and pressures. Three different plasma systems have been developed to treat organics in air, water, and soil. These systems are the Gas-Phase Corona Reactor (GPCR)III for treating air, the Liquid-Phase Corona Reactor for treating water, and In Situ Corona for treating soils. This presentation focuses on recent technical developments, commercial status, and project costs of OPCR as a cost-effective alternative to other air-purification technologies that are now in use to treat off-gases from site-remediation efforts as well as industrial emissions.
Date: June 1, 1995
Creator: Heath, W. O. & Birmingham, J. G.
Partner: UNT Libraries Government Documents Department

Technical Progress Report

Description: An ignition source was constructed that is capable of producing a pulsed corona discharge for the purpose of igniting mixtures in a test chamber. The corona generator can also be used as the ignition source for one cylinder on a test engine. The first tests were performed in a cylindrical shaped chamber to study the characteristics of the corona and analyze various electrode geometries. Next a test chamber was constructed that closely represented the dimensions of the combustion chamber of the test engine at USC. Combustion tests were performed in this chamber and various electrode diameters and geometries were tested. Higher peak pressures and faster pressure rise times were realized consistently in all test chambers versus standard spark plug ignition. A test engine was purchased for the project that has two spark plug ports per cylinder to The data acquisition and control system hardware for the USC engine lab was updated with new equipment. New software was also developed to perform the engine control and data acquisition functions including cylinder pressure monitoring. A ceramic corona electrode has been designed that fits in the new test engine and is capable of withstanding the pressures and temperatures encountered inside the combustion chamber. The corona ignition system was tested on the engine and an increase in both peak pressure and IMEP were seen in the initial test. There are issues that must be addressed before on-engine testing can continue such as EMF interference from the corona generator and electrical insulation on portions of the piston and cylinder head to prevent arcing. The EMF issue can be solved with proper shielding and grounding and various ceramic coatings are being researched for electrical insulation.
Date: August 26, 2004
Creator: Ronney, Paul D.
Partner: UNT Libraries Government Documents Department

Corona processing of insulating oil

Description: It is well known that sustained corona discharge in insulating oil lowers its dielectric strength and simultaneously reduces its corona resistance. Therefore, for operating stresses in the corona regime, activity typically increases with time and, if allowed to continue, eventually leads to breakdown of the oil and failure of the component or system. It is, therefore, common practice to periodically replace oil in devices such as large power transformers and switch gear before breakdown occurs. Sealed components such as capacitors are typically replaced. Recent experiments have demonstrated that the dielectric properties of corona weakened oil can not only be restored, but actually improved by a simple regeneration process. These experiments were carried out on high voltage pulse transformer windings which were operated at high rep rates until partial discharges formed. Reprocessing the oil after each operating cycle resulted in successively longer operational periods before partial discharges appeared. In a separate experiment, a process was developed to precondition transformer oil to raise its corona inception voltage before using it to insulate a high voltage component, thus giving it a longer initial service life for a given operating stress or permitting higher stress operation for limited operating times.
Date: July 1, 1996
Creator: Rohwein, G.J.
Partner: UNT Libraries Government Documents Department

Initial field test of High-Energy Corona process for treating a contaminated soil-offgas stream

Description: The High-Energy Corona (HEC) technology for treating process offgases has been under development at Pacific Northwest Laboratory (PNL) since 1991. The HEC process uses high-voltage electrical discharges in air to ionize the air, forming a low-temperature plasma that would be expected to destroy a wide variety of organic compounds in air. The plasma contains strong oxidants, possibly including hydroxyl radicals, hydroperoxy radicals, superoxide radicals, various excited as well as ionized forms of oxygen, high-energy electrons, and ultraviolet (UV) light. Because the high-voltage plasma is produced near ambient temperatures and pressures, yet exhibits extremely rapid destruction kinetics with relatively low power requirements, the HEC technique appears promising as a low-cost treatment technique (Virden et al. 1992). As part of the Volatile Organic Compound (VOC) Nonarid Integrated Demonstration (ID) at the DOE Savannah River Site, research activities were initiated in December 1991 to develop a prototype HEC process for a small-scale field demonstration to treat a soil-offgas stream contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) at varying concentrations. Over an 18-month period, the HEC technology was developed on a fast track, through bench and pilot scales into a trailer-mounted system that was tested at the Nonarid ID. Other national laboratories, universities, and private companies have also participated at the Nonarid ID to demonstrate a number of conventional, emerging and innovative approaches for treating the same soil-offgas stream.
Date: April 1, 1995
Creator: Shah, R R; Garcia, R E; Jeffs, J T; Virden, J W & Heath, W O
Partner: UNT Libraries Government Documents Department

Charging and corona modifications to the ORNL 25URC accelerator

Description: A chain-charge monitoring system was first installed in the 25URC accelerator in October 1982, and has provided valuable information about the charging system. Additions to the system during the past year have significantly increased the amount of information provided by the monitor. Cables connecting pickoff wheels and inductors in the terminal were improved to provide higher reliability of the charging system. The tube corona points supplied with the 25URC accelerator had a point-to-plane spacing of 0.175 inches. Our operating experience indicated that the corona currents for the normal gas pressure and voltage range of the accelerator were lower than optimum. Current-voltage characteristics of a three-needle point set were measured at several spacings and gas pressures to provide criteria for ordering new points.
Date: November 1, 1986
Creator: Ziegler, N.F. & McPherson, R.L.
Partner: UNT Libraries Government Documents Department

Erace--an integrated system for treating organic-contaminated sites

Description: The U.S. Department of Energy`s (DOE) Pacific Northwest Laboratory (PNL) is developing a suite of electrical technologies for treating sites contaminated with hazardous organic compounds. These include: (1) Six-Phase Soil Heating (SPSH) to remove volatile and semi-volatile organic compounds from soils; (2) In Situ Corona (ISC) to decompose nonvolatile and bound organic contaminants in soils; (3) High-Energy Corona (HEC) to treat contaminated off-gases; and (4) Liquid Corona (LC) to treat contaminated liquids. These four technologies comprise ERACE (Electrical Remediation at Contaminated Environments), an integrated system for accomplishing site remediation with little or no secondary wastes produced that would require off-site treatment or disposal. Each ERACE technology can be employed individually as a stand-alone treatment process, or combined as a system for total site remediation. For example, an ERACE system for treating sites contaminated with volatile organics would integrate SPSH to remove the contaminants from the soil, LC to continuously treat an aqueous stream condensed out of the soil off-gas, and HEC to treat non-condensibles remaining in the off-gas, before atmospheric release.
Date: November 1, 1994
Creator: Caley, S. M.; Heath, W. O.; Bergsman, T. M.; Gauglitz, P. A.; Pillay, C.; Moss, R. W. et al.
Partner: UNT Libraries Government Documents Department

OZONE TREATMENT OF SOLUBLE ORGANICS IN PRODUCED WATER (FEAC307)

Description: Oil production is shifting from ''shallow'' wells (0-650 ft water depth) to off-shore, deep-water operations (>2,600 ft.). Production from these operations is now approaching 20%. By 2007, it is projected that as much as 70% of the U.S. oil production will be from deep-water operations. The crude oil from these deep wells is more polar, thus increasing the amount of dissolved hydrocarbons in the produced water. Early data from Gulf of Mexico (GOM) wells indicate that the problem with soluble organics will increase significantly as deep-water production increases. Existing physical/chemical treatment technologies used to remove dispersed oil from produced water will not remove dissolved organics. GOM operations are rapidly moving toward design of high-capacity platforms that will require compact, low-cost, efficient treatment processes to comply with current and future water quality regulations. This project is an extension of previous research to improve the applicability of ozonation and will help address the petroleum industry-wide problem of treating water containing soluble organics. The goal of this project is to maximize oxidation of water-soluble organics during a single-pass operation. The project investigates: (1) oxidant production by electrochemical and sonochemical methods, (2) increasing the mass transfer rate in the reactor by forming microbubbles during ozone injection into the produced water, and (3) using ultraviolet irradiation to enhance the reaction if needed. Industrial collaborators include Chevron, Shell, Phillips, BP Amoco, Statoil, and Marathon Oil through a joint project with the Petroleum Environmental Research Forum (PERF). The research and demonstration program consists of three phases: (1) Laboratory testing in batch reactors to compare effectiveness of organics destruction using corona discharge ozone generation methods with hydrogen peroxide generated sonochemically and to evaluate the enhancement of destruction by UV light and micro-bubble spraying. (2) Continuous-flow studies to determine the efficacy of various contactors, the dependency of organics destruction ...
Date: March 20, 2001
Creator: Klasson, KT
Partner: UNT Libraries Government Documents Department

No-thermal plasma processing of VOCs and NO{sub x} at LLNL

Description: For the past few years, Lawrence Livermore National Laboratory has been conducting a comprehensive research program on the application of non-thermal plasmas for air pollution control and abatement. This program combines an extensive modeling effort with an experimental facility and test program. We believe that there are two major issues to be addressed in order to apply non-thermal plasma processing to air pollution control; these are electrical energy consumption and byproduct identification. The thrust of our work has been to understand the scalability of the non-thermal process by focusing on the energy efficiency of the non-thermal process and to identify the byproducts to ensure that effluent gases from a non-thermal processor are benign. We have compared different types of electrical discharge reactors both theoretically and experimentally. Our interests in the application of non-thermal plasmas vary from the destruction of volatile organic compounds (VOCs) to NO{sub x} reduction for mobile applications. This paper will discuss the processing of both NO{sub x} and VOCs by non-thermal plasmas at LLNL.
Date: February 15, 1995
Creator: Merritt, B.T.; Hsiao, M.C.; Penetrante, B.M.; Vogtlin, G.E. & Wallman, P.H.
Partner: UNT Libraries Government Documents Department

Enhancement of methane conversion using electric fields. Quarterly report, April--June 1995

Description: The goal of this project is the development of novel, economical processes for the conversion of natural gas to more valuable products such as methanol, ethylene, and other organic oxygenates or higher hydrocarbons. The methodologies of the project are to investigate and develop low temperature electric discharges and electric field- enhanced catalysis for carrying out these conversions. In the case of low temperature discharges, the conversion is carried out at ambient temperature which in effect trades high temperature thermal energy for electric energy as the driving force for conversion. The low operating temperatures relax the thermodynamic constraints on the product distribution found at high temperatures and also remove the requirements of large thermal masses required for current technologies. With the electric field-enhanced conversion, the operating temperatures are expected to be below those currently required for such processes as oxidative coupling, thereby allowing for a higher degree of catalytic selectivity while maintaining high activity.
Date: July 1, 1995
Creator: Mallinson, R.G. & Lobban, L.L.
Partner: UNT Libraries Government Documents Department

CORONA DISCHARGE IGNITION FOR ADVANCED STATIONARY NATURAL GAS ENGINES

Description: An ignition source was constructed that is capable of producing a pulsed corona discharge for the purpose of igniting mixtures in a test chamber. This corona generator is adaptable for use as the ignition source for one cylinder on a test engine. The first tests were performed in a cylindrical shaped chamber to study the characteristics of the corona and analyze various electrode geometries. Next a test chamber was constructed that closely represented the dimensions of the combustion chamber of the test engine at USC. Combustion tests were performed in this chamber and various electrode diameters and geometries were tested. The data acquisition and control system hardware for the USC engine lab was updated with new equipment. New software was also developed to perform the engine control and data acquisition functions. Work is underway to design a corona electrode that will fit in the new test engine and be capable igniting the mixture in one cylinder at first and eventually in all four cylinders. A test engine was purchased for the project that has two spark plug ports per cylinder. With this configuration it will be possible to switch between corona ignition and conventional spark plug ignition without making any mechanical modifications.
Date: September 12, 2003
Creator: Ronney, Dr. Paul D.
Partner: UNT Libraries Government Documents Department

FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

Description: Western Research Institute (WRI) initiated exploratory work towards the development of new field screening methodology and a test kit to measure halogenated volatile organic compounds (VOCs) in the field. Heated diode and corona discharge sensors are commonly used to detect leaks of refrigerants from air conditioners, freezers, and refrigerators. They are both selective to the presence of carbon-halogen bonds. Commercially available heated diode and corona discharge leak detectors were procured and evaluated for halogenated VOC response. The units were modified to provide a digital readout of signal related to VOC concentration. Sensor response was evaluated with carbon tetrachloride and tetrachloroethylene (perchloroethylene, PCE), which represent halogenated VOCs with and without double bonds. The response characteristics were determined for the VOCs directly in headspace in Tedlar bag containers. Quantitation limits in air were estimated. Potential interferences from volatile hydrocarbons, such as toluene and heptane, were evaluated. The effect of humidity was studied also. The performance of the new devices was evaluated in the laboratory by spiking soil samples and monitoring headspace for halogenated VOCs. A draft concept of the steps for a new analytical method was outlined. The results of the first year effort show that both devices show potential utility for future analytical method development work towards the goal of developing a portable test kit for screening halogenated VOCs in the field.
Date: June 1, 2002
Creator: Schabron, John F.; Jr., Joseph F. Rovani & Bomstad, Theresa M.
Partner: UNT Libraries Government Documents Department

FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

Description: Western Research Institute (WRI) is continuing work toward the development of new screening methodology and a test kit to measure halogenated volatile organic compounds (VOCs) in the field. Heated diode and corona discharge sensors are commonly used to detect leaks of refrigerants from air conditioners, freezers, and refrigerators. They are both selective to the presence of halogens. In prior work, the devices were tested for response to carbon tetrachloride, heptane, toluene, and water vapors. In the current work, sensor response was evaluated with sixteen halogenated VOCs relative to carbon tetrachloride. The results show that the response of the various chlorinated VOCs is within an order of magnitude of the response to carbon tetrachloride for each of the sensors. Thus, for field screening a single response factor can be used. Both types of leak detectors are being further modified to provide an on-board LCD signal readout, which is related to VOC concentration. The units will be fully portable and will operate with 115-V line or battery power. Signal background, noise level, and response data on the Bacharach heated diode detector and the TIF corona discharge detector show that when the response curves are plotted against the log of concentration, the plot is linear to the upper limit for the particular unit, with some curvature at lower levels. When response is plotted directly against concentration, the response is linear at the low end and is curved at the high end. The dynamic ranges for carbon tetrachloride of the two devices from the lower detection limit (S/N=2) to signal saturation are 4-850 vapor parts per million (vppm) for the corona discharge unit and 0.01-70 vppm for the heated diode unit. Additional circuit modifications are being made to lower the detection limit and increase the dynamic response range of the corona discharge unit. The ...
Date: July 1, 2003
Creator: Schabron, John F.; Joseph F. Rovani, Jr. & Bomstad, Theresa M.
Partner: UNT Libraries Government Documents Department

A COMPACT CORONA DISCHARGE DEVICE (CDD{trademark}) FOR NON-THERMAL PLASMA GENERATION IN GASOLINE OR DIESEL ENGINE EXHAUST

Description: Higher fuel economy targets and hybrid vehicles are increasing the marketability of diesel engines. But in order to implement the growth of diesels to achieve the fuel economy benefits, all emission regulation issues must be met. To do this traps and catalysts are being utilized. One of the main problems is finding a technology that enables the exhaust emission system to not only meet the emission requirements when new, but also to meet them at the regulated intermediate and full life requirements. Work is being done that enables catalysts to remain highly efficient throughout their full life. It is done by using a corona discharge device (CDD{trademark}) that introduces non-thermal plasma into the exhaust ahead of the converter. This low power device creates radicals that alter the chemistry of the exhaust so as to limit the poisoning of the catalyst. This can be done without so called ''purge'' cycles that lower fuel economy and degrade catalyst long-term durability. This device has been developed, not as a laboratory tool, but as a production ready product and is the first of its kind that is commercially available for testing. It is this product, the Corona Discharge Device, CDD{trademark}, which will be described.
Date: August 20, 2000
Creator: Nowak,Victor J.
Partner: UNT Libraries Government Documents Department

Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

Description: The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Several pulsed corona discharge (PCD) reactors have been fabricated and used to dissociate H{sub 2}S into hydrogen and sulfur. Visual observation shows that the corona is not uniform throughout the reactor. The corona is stronger near the top of the reactor in argon, while nitrogen and mixtures of argon or nitrogen with H{sub 2}S produce stronger coronas near the bottom of the reactor. Both of these effects appear to be explainable base on the different electron collision interactions with monatomic versus polyatomic gases. A series of experiments varying reactor operating parameters, including discharge capacitance, pulse frequency, and discharge voltage were performed while maintaining constant power input to the reactor. At constant reactor power input, low capacitance, high pulse frequency, and high voltage operation appear to provide the highest conversion and the highest energy efficiency for H{sub 2}S decomposition. Reaction rates and energy efficiency per H{sub 2}S molecule increase with increasing flow rate, although overall H{sub 2}S conversion decreases at constant power input. Voltage and current waveform analysis is ongoing to determine the fundamental operating characteristics of the reactors. A metal infiltrated porous ceramic membrane was prepared using vanadium as the metal and an alumina tube. Experiments with this type of membrane are continuing, but the results thus far have been consistent with those obtained in previous project years: plasma driven permeation or superpermeability has not been observed. A ...
Date: September 30, 2006
Creator: Argyle, Morris D.; Ackerman, John F.; Muknahallipatna, Suresh; Hamann, Jerry C.; Legowski, Stanislaw; Zhao, Guibing et al.
Partner: UNT Libraries Government Documents Department

Personal overview of solar wind 6

Description: The author reviews papers presented at the Solar Wind 6 Proceedings. The particular topics discussed are solar wind acceleration theory, heliosphere production of solar winds, coronal mass ejections, interplanetary shock disturbance, and solar wind ionic composition. A concern for the steady decline in solar wind observations is expressed. (LSP)
Date: January 1, 1987
Creator: Gosling, J.T.
Partner: UNT Libraries Government Documents Department

High-Energy Corona for destruction of volatile organic contaminants in process off-gases

Description: A small (2 scfm) High-Energy Corona (HEC) reactor was developed to produce a non-equilibrium plasma in a concentric-cylinder geometry. A volume-filling plasma was produced in a packed bed, and initial tests have demonstrated the ability to destroy up to 1500 ppM trichloroethylene at a flow rate of 1.4 scfm, with greater than 99% destruction observed. Destruction efficiency is examined as a function of inlet TCE concentration, bed height (residence time) and applied voltage. Hydrochloric acid appears to be the primary chlorinated byproduct, and can be removed by conventional wet or dry scrubbing.
Date: August 1, 1992
Creator: Virden, J. W.; Heath, W. O.; Goheen, S. C.; Miller, M. C.; Mong, G. M. & Richardson, R. L.
Partner: UNT Libraries Government Documents Department

Separations techniques for recovery and/or removal of toxic metals from spent textile dyebaths

Description: The Textile Resource Conservation Project (TReC) is a major initiative of the American Textile Partnership (AMTEX) focusing on energy and the environment. The largest proposed project in the TReC is Raw Material Recovery and Reuse. The main task within the Raw Material Recovery and Reuse Project is Textile Chemical Recovery. The initial focus of this task is the separation/removal of colorants from solution. Screening studies were performed at a number of US Department of Energy National Laboratories to identify promising technologies for the treatment and recovery of dyes containing toxic metals. These dyes were chosen because of the environmental concern associated with their disposal. The research group at Pacific Northwest Laboratory (PNL) took two approaches to the removal and recovery of the toxic metals in the dyes. One approach was to react or destroy the organic fraction of the dye, releasing the metals for conventional separation such as ion exchange. PNL evaluated the Rapid Thermal Decomposition of precursors in Solution (RTDS) and Corona Discharge processes for metal release. The other approach was to separate and concentrate the dye, metal-complex intact, from the bulk of the spent solution. Membrane separation was evaluated for recovery of the dyes with the metals left intact. The RTDS process was found to be effective for destroying color and releasing or precipitating metals for recovery. Corona Discharge was effective at selectively destroying color, but the metals were not sufficiently released to allow recovery with a chelating resin. Ultrafiltration membranes were effective for separating and recovering the metal-containing dye as a potentially reusable concentrated stream.
Date: February 1, 1994
Creator: Babocsi, E. E. & Hallen, R. T.
Partner: UNT Libraries Government Documents Department

Basic energy efficiency of plasma production in electrical discharge and electron beam reactors

Description: Non-thermal plasma processing is an emerging technology for the abatement of volatile organic compounds (VOCs) and nitrogen oxides (NO{sub x}) in atmospheric pressure gas streams. Either electrical discharge of electron beam methods can produce these plasmas. This paper presents a comparative assessment of various non-thermal plasma reactors. The goal of our project is two-fold: (1) to understand the feasibility and scalability of various non-thermal plasma reactors by focusing on the energy efficiency of the electron and chemical kinetics, and (2) to optimize process parameters and provide performance and economic data. Experimental results using a compact electron beam reactor, pulsed corona reactor and dielectric-barrier discharge will be presented. These reactors have been used to study the removal of NO{sub x} and a wide variety of VOCs. The effects of background gas decomposition and gas temperature on the decomposition chemistry have been studied. The decomposition mechanisms are discussed to illustrate how the chemistry could strongly affect the economics of the process. An analysis of the electron kinetics show that electrical discharge reactors are the most suitable only for processes requiring O radicals. For pollution control applications requiring copious amounts of electrons, ions, N atoms or OH radicals, the sue of electron beam reactors is generally the best way of minimizing the electrical power consumption.
Date: November 1, 1996
Creator: Penetrante, B.M.; Hsiao, M.C.; Bardsley, J.N.; Merritt, B.T.; Vogtlin, G.E.; Kuthi, A. et al.
Partner: UNT Libraries Government Documents Department

Combined removal of SO{sub x} and NO{sub x} from flue gas using non-thermal plasma. Technical report, March 1--May 31, 1995

Description: A model has been developed to predict the performance of a dielectric-barrier discharge for various parameters. The model calculations have been compared with experimental results and are in close agreement for both SO{sub 2}/NO removal. The reaction scheme shows that OH is the most important radical for SO{sub 2} removal with the final product being H{sub 2}SO{sub 4}. Whereas for NO removal both oxidation by OH to form HNO{sub 3} and reduction by N to form N{sub 2} are important channels.
Date: December 31, 1995
Creator: Dhali, S.K.
Partner: UNT Libraries Government Documents Department

Alternative Ionization Methods for Particle Mass Spectrometry

Description: The objective of this project is to enhance the capabilities of a real-time airborne particle mass spectrometer by implementing matrix-independent methods for sample ionization. The enhancements should result in improved sensitivity for trace substances and, more importantly, permit quantitative determination of the presence of target species in microparticle samples on an individual particle basis. We have used two different approaches to eliminate matrix effects on quantitative accuracy. Both rely on delayed ionization of ablated/desorbed neutral species so that ionization of target substances occurs after most of the expansion collisions have taken place. Resonance ionization by a tunable pulsed laser permits selective ionization of target species, with the laser tuned to a resonance transition from the ground state to an excited state of the target. Additional photons of the same (when possible) or different energy make up the energy required for ionization. The other approach is to perform the laser ablation step within a discharge so that desorbed neutrals are ionized by reactions with the plasma. Electron capture generates negative ions of substances with high electron affinity while electron impact ionization, associative ionization, and Penning ionization from excited metastable species produce positive ions in the discharge. Both atmospheric pressure Corona discharge ionization and glow discharge ionization at reduced pressure are being explored. Discharge ionization is relatively nonselective so that target specificity must be obtained through the mass spectral or MS/MS results.
Date: June 1, 2004
Creator: Whitten, William & Reilly, Peter T.
Partner: UNT Libraries Government Documents Department

NOVEL COMPOSITE HYDROGEN-PERMEABLE MEMBRANES FOR NON-THERMAL PLASMA REACTORS FOR THE DECOMPOSITION OF HYDROGEN SULFIDE

Description: The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Experiments involving methane conversion reactions were conducted with a preliminary pulsed corona discharge reactor design in order to test and improve the reactor and membrane designs using a non-toxic reactant. This report details the direct methane conversion experiments to produce hydrogen, acetylene, and higher hydrocarbons utilizing a co-axial cylinder (CAC) corona discharge reactor, pulsed with a thyratron switch. The reactor was designed to accommodate relatively high flow rates (655 x 10{sup -6} m{sup 3}/s) representing a pilot scale easily converted to commercial scale. Parameters expected to influence methane conversion including pulse frequency, charge voltage, capacitance, residence time, and electrode material were investigated. Conversion, selectivity and energy consumption were measured or estimated. C{sub 2} and C{sub 3} hydrocarbon products were analyzed with a residual gas analyzer (RGA). In order to obtain quantitative results, the complex sample spectra were de-convoluted via a linear least squares method. Methane conversion as high as 51% was achieved. The products are typically 50%-60% acetylene, 20% propane, 10% ethane and ethylene, and 5% propylene. First Law thermodynamic energy efficiencies for the system (electrical and reactor) were estimated to range from 38% to 6%, with the highest efficiencies occurring at short residence time and low power input (low specific energy) where conversion is the lowest (less than 5%). The highest methane conversion of 51% occurred at a residence time of 18.8 s with a flow rate ...
Date: July 1, 2004
Creator: Argyle, Morris D.; Ackerman, John F.; Muknahallipatna, Suresh; Hamann, Jerry C.; Legowski, Stanislaw; Zhang, Ji-Jun et al.
Partner: UNT Libraries Government Documents Department

OH generation in steam-air pulsed corona

Description: The measurement of OH concentration in a pulsed corona discharge through a steam-air mixture is compared with a chemical kinetics model. The original motivation was to develop a technological hydroxilizer for oxidizing gas pollutants to acids. Time dependent measurements of the 3,064 {angstrom} emission of OH indicate a production of nearly 4 ppm within a spark. This measurement was accomplished by a 1 ns resolution photomultiplier with a 100 {angstrom} filter centered at 3080 {angstrom}. The discharge occurs across a 1 cm coaxial gap between a central anode tube and an outer cylindrical cathode cased in glass and at ground potential. The water-air mixture is of equal proportions and at 1 atmosphere. Pulsed voltage of 38 kV and 60 ns risetime produces a 60 A, 20 ns spark. The model predicts comparable OH production by dissociation in the air-water mixture after 100 ns of 10{sup 12} electrons/cm{sup 3}. The electron density is set to zero during the subsequent 100 {mu}s in the model, and thereafter OH is seen as a short-lived reaction product of HO{sub 2} with O and N atoms. The sequence of reaction is: 100 ns of dissociation to peak OH concentration, 0.2 {mu}s for hydrogen atom loss and HO{sub 2} formation, 20 {mu}s for O atom loss and O{sub 3} formation, beyond 20 {mu}s NO formation from N atoms with OH and HO{sub 2}. In the model HO{sub 2} ultimately decays by slowly forming H{sub 2}O{sub 2}, so it may be viewed as a stable fuel which produces OH when combined with atomic oxygen or nitrogen.
Date: May 1, 1995
Creator: Garcia, M. & Chang, B.
Partner: UNT Libraries Government Documents Department