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Geothermal direct-contact heat exchange. Final report

Description: A glass direct contact heat exchange column was operated in the laboratory at atmospheric pressure using hot water and normal hexane. Column internals tested included an empty column, sieve trays, disk-and-doughnut trays, and two types of packing. Operation was very smooth in all cases and the minimum temperature approaches varied from less than 1{sup 0}C for packing to 13{sup 0}C for the empty column. High heat transfer rates were obtained in all cases, however, columns should be sized on the basis of liquid and vapor traffic. The solubilities of hydrocarbons were determined for normal hexane, pentane and butane in water and sodium chloride and calcium chloride brines at various temperatures. The values seem to be internally consistent and salt content was found to depress hydrocabon solubility. Laboratory stripping tests showed that gas stripping can be used to remove hydrocarbon from reject hot water from the direct contact heat exchange column. Although the gas volumes required are small, stripping gas requirements cannot be accurately predicted without testing. A computer program was used to study the effect of operating variables on thermodynamic cycle efficiencies. Optimum efficiencies for the moderate brine conditions studied were obtained with isopentane as working fluid and relatively low operating pressure. A preliminary design for a 50 MWe plant was prepared and plant capital cost and operating cost were estimated. These costs were combined with previously developed brine production and power transmission costs to provide an estimate of the cost of delivered power for a geothermal field at Heber, California. A pilot plant program is described that would be suitable for continuing the investigation of the direct contact process in the field. The program includes a suggested schedule and the estimated cost.
Date: June 10, 1976
Creator: Sims, A.V.
Partner: UNT Libraries Government Documents Department

Geothermal direct contact heat exchange. Final report

Description: A glass direct contact heat exchange column was operated in the laboratory. The column was operated at atmospheric pressure using hot water and normal hexane. Column internals testing included an empty column, sieve trays, disk-and-doughnut trays, and two types of packing. Operation was very smooth in all cases and the minimum temperature approaches varied from less than 1/sup 0/C for packing to 13/sup 0/C for the empty column. High heat transfer rates were obtained in all cases, however, columns should be sized on the basis of liquid and vapor traffic. The solubilities of hydrocarbons were determined for normal hexane, pentane and butane in water and sodium chloride and calcium chloride brines at various temperatures. The values seem to be internally consistent and salt content was found to depress hydrocarbon solubility. Laboratory stripping tests showed that gas stripping can be used to remove hydrocarbon from reject hot water from the direct contact heat exchange column. Although the gas volumes required are small, stripping gas requirements cannot be accurately predicted without testing. A computer program was used to study the effect of operating variables on the thermodynamic cycle efficiencies. Optimum efficiencies for the moderate brine conditions studied were obtained with isopentane as working fluid and relatively low operating pressure. A preliminary design for a 50 MWe plant was prepared and plant capital cost and operating cost were estimated. These costs were combined with previously developed brine production and power transmission costs to provide an estimate of the cost of delivered power for a geothermal field at Heber, California. A pilot plant program is described that would be suitable for continuing the investigation of the direct contact process in the field. The program includes a suggested schedule and the estimated cost.
Date: June 10, 1977
Creator: Sims, A. V.
Partner: UNT Libraries Government Documents Department

A Rapid Compression Machine Modelling Study of the Heptane Isomers

Description: Previously we have reported on the combustion behavior of all nine isomers of heptane in a rapid compression machine (RCM) with stoichiometric fuel and ''air'' mixtures at a compressed gas pressure of 15 atm. The dependence of autoignition delay times on molecular structure was illustrated. Here, we report some additional experimental work that was performed in order to address unusual results regarding significant differences in the ignition delay times recorded at the same fuel and oxygen composition, but with different fractions of nitrogen and argon diluent gases. Moreover, we have begun to simulate these experiments with detailed chemical kinetic mechanisms. These mechanisms are based on previous studies of other alkane molecules, in particular, n-heptane and iso-octane. We have focused our attention on n-heptane in order to systematically redevelop the chemistry and thermochemistry for this C{sub 7} isomer with the intention of extending our greater knowledge gained to the other eight isomers. The addition of new reaction types, that were not included previously, has had a significant impact on the simulations, particularly at low temperatures.
Date: May 10, 2005
Creator: Silke, E J; Curran, H J; Simmie, J M; Pitz, W J & Westbrook, C K
Partner: UNT Libraries Government Documents Department

Calculated photon KERMA factors based on the LLNL EGDL (Evaluated Gamma-Ray Data Library) data file

Description: Photon (Gamma-Ray) KERMA factors calculated from the LLNL EGDL (Evaluated Gamma-Ray Data Library) file are tabulated for the elements from Z=1 to Z=30 and for 15 composite materials. The KERMA factors are presented for 191 energy groups over the incident photon energy range from 100 eV to 100 MeV. 3 refs.
Date: October 10, 1986
Creator: Howerton, R.J.
Partner: UNT Libraries Government Documents Department

Methyl chloride via oxyhydrochlorination of methane

Description: Purpose of this contract is to develop a process for converting light alkane gases to methyl chloride via oxyhydrochlorination using highly selective, stable catalysts (Cu) in either fixed-bed or fluid-bed reactors. Catalyst development and micro-packed bed screening studies are underway. Engineering support for pre-design on the miniplant is struggling with the unit operations problem associated with separation of products from unreacted methane.
Date: February 10, 1992
Creator: Naasz, B.
Partner: UNT Libraries Government Documents Department

Winter fuels report, week ending January 4, 1991. [Contains glossary]

Description: The Winter Fuels Report is intended to provide concise, timely information on the following: distillate fuel oil net production, imports and stocks for all PADD's and product supplied on a US level; propane net production, imports and stocks for Petroleum Administration for Defense Districts (PADD), I, II, and III; natural gas supply and disposition and underground storage for the United States and consumption for all PADD's; residential and wholesale pricing data for propane and heating oil for those States participating in the joint Energy Information Administration (EIA)/State Heating Oil and Propane Program; crude oil and petroleum price comparisons for the United States and selected cities; and US total heating degree-days by city. 34 figs., 12 tabs.
Date: January 10, 1991
Partner: UNT Libraries Government Documents Department

Winter fuels report, week ending October 4, 1991. [CONTAINS GLOSSARY]

Description: This report is intended to provide concise, timely information to the industry, the press, policymakers, consumers, analysts, and State and local governments on the following topics: distillate fuel oil net production, imports and stocks for all Petroleum Administration for Defense Districts (PADD) and product supplied on a US level; propane net production, imports and stocks for PADD's 1, 2, and 3; natural gas supply and disposition and underground storage for the United States and consumption for all PADD's; residential and wholesale pricing data for propane and heating oil for those States participating in the joint Energy Information Administration (EIA)/State Heating Oil and Propane Program; crude oil and petroleum price comparisons for the United States and selected cities; and US total heating degree-days by city. 37 figs., 13 tabs.
Date: October 10, 1991
Partner: UNT Libraries Government Documents Department

Synthesis of octane enhancers during slurry-phase Fischer-Tropsch

Description: The objective of this project is to investigate three possible routes to the formation of ethers, in particular methyl tert-butyl ether (MTBE), during slurry phase Fischer-Tropsch reaction. The three reaction schemes to be investigated are: Addition of isobutylene during the formation of methanol and/or higher alcohols directly from CO and H{sub 2} during slurry-phase Fischer-Tropsch. Addition of isobutylene to FT liquid products including alcohols in a slurry-phase reactor containing an MTBE or other acid catalyst. Addition of methanol to slurry phase FT synthesis making iso-olefins.
Date: June 10, 1992
Creator: Marcelin, G.
Partner: UNT Libraries Government Documents Department

Heavy recycle solvent studies in two-stage coal liquefaction. Final technical report, September 1, 1982-December 30, 1983

Description: The objective of this program has been to study the chemistry of the components with high boiling points in a direct coal liquefaction recycle solvent and to identify those components which lead to higher overall yields and improved product stability in the initial coal dissolution step of direct coal liquefaction processes. The major conclusions are: -454 C recycle solvent is primarily aromatic hydrocarbons (73%) and contains almost no asphaltenes; +454 C recycle solvent is primarily asphaltenes and aromatic hydrocarbons; recycle solvent also contains aliphatic hydrocarbons, N-containing aromatics and O-containing aromatics; heteroatoms in coal derived materials seem to be grouped by type, i.e. acidic O and basic N and sulfur occur together; under helium a small net amount of hydrogen and more CO and CO/sub 2/ are produced than under hydrogen; under hydrogen the amounts of H/sub 2/S and hydrocarbon gases are increased and a small amount of hydrogen gas is usually consumed; overall coal conversions to THF solubles are improved by adding more -454 C solvent but decreased by adding +454 C solvent; for added fractions of -454 C solvent the pecent conversion to THF solubles increases in the order aromatic hydrocarbons (+7.2) > aliphatic hydrocarbons (+0.8) > no added solvent (0.0) > N-containing aromatics (-0.9) > O-containing aromatics (-22.1); percent conversion to THF solubles using -454 C solvent with +454 C solvent fractions added decrease in the order aliphatics (+3.7) > aromatic hydrocarbons (+3.0) > no added solvent (0.0) > O-containing aromatics (-9.3) > N-containing aromatics (-13.3); of the +454 C solvent components, aromatic hydrocarbons and aliphatic hydrocarbons are beneficial but total only approx. 25% of the +454 C recycle solvent; and steric effects may be important in determining the effectiveness of the heavier solvent components as liquefaction solvents. 28 references, 25 figures, 31 tables.
Date: January 10, 1984
Creator: Longanbach, J. R.
Partner: UNT Libraries Government Documents Department

Enhancement of methane production in the anaerobic digestion of sewage sludges

Description: The effect of powdered activated carbon on stressed anaerobic digesters utilizing a sewage sludge substrate was evaluated. The addition of carbon resulted in increased methanee production and greater process stability. The degree of enhancement appeared to be proportional to carbon concentration over the dose range studied (500-10,000 mg/l). A maximum increase in methane production of about 150% was observed at the highest carbon dose. The effect of 1500 mg/l carbon, 4000 mg/l coal, and 4000 mg/l flyash on relatively unstressed digesters was also examined. Units using a sewage sludge substrate were operated at 10 and 20 day SRT's. A 12% increase in methane production was observed in a carbon dosed digester functioning at a 10 day detention time. Enhancement was not evident with carbon at a 20 day SRT. No significant improvement in methane production was obtained in any of the digesters using coal or flyash as additives. Using the experimental data, a technique was developed for estimating the efficiencies of the methane forming and acid forming steps in the anaerobic digestion process. The results indicated that in stressed systems both stages of the digestion process were enhanced by the addition of powdered carbon. In the relatively unstressed systems, when enhancement did occur, only the scid forming step was affected. This information will supplement current research at determining the mechanism(s) by which carbon enhances the digestion process.Based on the results of this study, it appears that the benefits of carbon addition are greatest in stressed systems. Only very moderate increases in methane production would probably be attainable in well operating digesters. Coal and flyash do not seem to be effective in enhancing gas production in unstressed systems. However, their effectiveness has not been tested in stressed situations.
Date: May 10, 1978
Creator: Spencer, R.R.
Partner: UNT Libraries Government Documents Department

Mild Catalytic methods for Alkyl-Alkyl Bond Formation

Description: Overview of Research Goals and Accomplishments for the Period 07/01/06 – 06/30/07: Our overall research goal is to transform the rapidly emerging synthetic chemistry involving alkyl-alkyl cross-couplings into more of a mechanism-based field so that that new, rationally-designed catalysts can be performed under energy efficient conditions. Our specific objectives for the previous year were 1) to obtain a proper electronic description of an active catalyst for alkyl-alkyl cross-coupling reactions and 2) to determine the effect of ligand structure on the rate, scope, selectivity, and functional group compatibility of C(sp3)-C(sp3) cross-coupling catalysis. We have completed both of these initial objectives and established a firm base for further studies. The specific significant achievements of the current grant period include: 1) we have performed magnetic and computational studies on (terpyridine)NiMe, an active catalyst for alkyl-alkyl cross couplings, and have discovered that the unpaired electron resides heavily on the terpyridine ligand and that the proper electronic description of this nickel complex is a Ni(II)-methyl cation bound to a reduced terpyridine ligand; 2) we have for the first time shown that alkyl halide reduction by terpyridyl nickel catalysts is substantially ligand based; 3) we have shown by isotopic labeling studies that the active catalyst (terpyridine)NiMe is not produced via a mechanism that involves the formation of methyl radicals when (TMEDA)NiMe2 is used as the catalyst precursor; 4) we have performed an extensive ligand survey for the alkyl-alkyl cross-coupling reactions and have found that electronic factors only moderately influence reactivity in the terpyridine-based catalysis and that the most dramatic effects arise from steric and solubility factors; 5) we have found that the use of bis(dialkylphosphino)methanes as ligands for nickel does not produce active catalysts for cross-coupling but rather leads to bridging hydride complexes of varying geometries; 6) we have determined that the geometry of aforementioned bridging ...
Date: August 10, 2009
Creator: Vicic, David A
Partner: UNT Libraries Government Documents Department

Gallium Zeolites for Light Paraffin Aromatization

Description: The primary original goal of this project was to investigate the active state of gallium-containing MFI catalysts for light paraffin aromatization, in particular the state of gallium in the active material. Our original hypothesis was that the most active and selective materials were those which contained gallium zeolitic cations, and that previously reported conditions for the activation of gallium-containing catalysts served to create these active centers. We believed that in high silica materials such as MFI, ion-exchange is most effectively accomplished with metals in their 1+ oxidation state, both because of the sparsity of the anionic ion-exchange sites associated with the zeolite, and because the large hydration shells associated with aqueous 3+ cations hinder transport. Metals such as Ga which commonly exist in higher oxidation states need to be reduced to promote ion-exchange and this is the reason that reduction of gallium-containing catalysts for light paraffin aromatization often yields a dramatic enhancement in catalytic activity. We have effectively combined reduction with ion-exchange and we term this combined process ''reductive solid-state ion-exchange''. Our hypothesis has largely been proven true, and a number of the papers we have published directly address this hypothesis.
Date: February 10, 1999
Creator: Price, G.L. & Dooley, K.M.
Partner: UNT Libraries Government Documents Department