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Fischer-Tropsch synthesis in supercritical fluids. Final report

Description: The objective of this study was to investigate Fischer-Tropsch Synthesis (FTS) in the supercritical phase employing a commercial precipitated iron catalysts. As the supercritical fluid the authors used propane and n-hexane. The catalyst had a nominal composition of 100 Fe/5 Cu/4.2 K/25 SiO{sub 2} on mass basis and was used in a fixed bed reactor under both normal (conventional) and supercritical conditions. Experimental data were obtained at different temperatures (235 C, 250 C, and 260 C) and synthesis gas feed compositions (H{sub 2}/CO molar feed ratio of 0.67, 1.0 and 2.0) in both modes of operation under steady state conditions. The authors compared the performance of the precipitated iron catalyst in the supercritical phase, with the data obtained in gas phase (fixed bed reactor) and slurry phase (STS reactor). Comparisons were made in terms of bulk catalyst activity and various aspects of product selectivity (e.g. lumped hydrocarbon distribution and olefin content as a function of carbon number). In order to gain better understanding of the role of intraparticle mass transfer during FTS under conventional or supercritical conditions, the authors have measured diffusivities of representative hydrocarbon products in supercritical fluids, as well as their effective diffusion rates into the pores of catalyst at the reaction conditions. They constructed a Taylor dispersion apparatus to measure diffusion coefficients of hydrocarbon products of FTS in sub and supercritical ethane, propane, and hexane. In addition, they developed a tracer response technique to measure the effective diffusivities in the catalyst pores at the same conditions. Based on these results they have developed an equation for prediction of diffusion in supercritical fluids, which is based on the rough hard sphere theory.
Date: December 31, 1998
Creator: Akgerman, A. & Bukur, D.B.
Partner: UNT Libraries Government Documents Department

Separation of Fischer-Tropsch wax from catalyst by supercritical extraction. Quarterly progress report, October 1, 1996--December 31, 1996

Description: One of the major objectives of this research project is to predict the phase behavior of model wax compounds in dense supercritical fluids such as hexane. Because initial results with the SAFT equation have been less promising than expected, the group at North Carolina State University has focused their recent attention on cubic equations of state, in particular the Peng-Robinson and Soave-Redlich-Kwong versions. The focus of this work has been on developing correlations that can be used to predict binary interaction parameters (i.e., k{sub ij}s) for a given binary wax-solvent system. As a first step, k{sub ij}s were first calculated from experimental data on systems containing alkanes between nC{sub 4} and nC{sub 23} at temperatures between 25 and 357{degrees} C. Attempts were then made to correlate these parameters with specific pure component properties of the alkanes of interest. Reasonably good agreement between experimental and predicted k{sub ij}s was found using a correlation that incorporates both temperature and the molecular size of the alkanes. As phase equilibrium data becomes available for higher molecular weight model wax compounds, the ability of the correlation to handle such systems will need to be tested. The phase equilibrium apparatus is currently undergoing modifications that will allow the system to run components that are solids at ambient temperatures. Some problems are still being resolved, as the heavy component tends to precipitate in the sample lines. Modifications have been made that should allow the system to operate reliably.
Date: January 1, 1997
Creator: Joyce, P.C. & Thies, M.C.
Partner: UNT Libraries Government Documents Department

Catalytic steam gasification of carbon

Description: Unsupported carbide powders with high specific surface area, namely {alpha}-WC (35 m{sup 2}/g, hexagonal), {beta}-WC{sub 0.61} (100 m{sup 2}/g, cubic face centered) and {beta}-WC{sub 0.5} (15 m{sup 2}/g, hexagonal) have been prepared. The key element in this preparation is the successful removal of surface polymeric carbon by careful gasification to methane by means of dihydrogen. These tungsten carbide powders have been used in catalytic reactions of oxidation of H{sub 2} and hydrogenolysis of alkanes, such as butane, hexane, and neopentane.
Date: December 31, 1990
Creator: Boudart, M.
Partner: UNT Libraries Government Documents Department

Separation of Fischer-Tropsch wax from catalyst using supercritical fluid extraction. Quarterly technical progress report, 1 October 1995--31 December 1995

Description: The objective of this research project is to evaluate the potential of supercritical fluid (SCF) extraction for separating the catalyst slurry of a Fischer-Tropsch slurry bubble column (SBC) reactor into two fractions: (1) a catalyst-free wax containing less than 10 ppm particulate matter and (2) a concentrated catalyst slurry that is ready for recycle or regeneration. The wax will be extracted with a hydrocarbon solvent that has a critical temperature near the operating temperature of the SBC reactor, i.e., 200-300{degrees}C. Initial work is being performed using n-hexane as the solvent. During the reporting period, work on the small-scale, continuous-flow apparatus continued. Initial experiments have been performed on a binary mixture of n-hexane (solvent) and squalane (model compound) at 200{degrees}C. A total of fifteen samples were collected at 135, 160, and 208 psig, with pressures being controlled to within {plus_minus}2 psi. Results indicate that the equilibrium phase compositions can in principle be measured to a reproducibility of {plus_minus}0.5% in the squalane-rich bottomphase and {plus_minus}2% in the hexane-rich top phase, with respect to the minor component. However, other data measured at these same conditions at another time exhibited scatter that was as much as 5 times greater. We believe that improvements in (1) the method of preheating the feed to the view cell/phase separator and to (2) the sample collection technique are required before data of high accuracy can consistently be generated. The apparatus modifications required to effect these improvements are currently underway and should be completed by the middle of February.
Date: June 1, 1996
Creator: Thies, M.C. & Joyce, P.C.
Partner: UNT Libraries Government Documents Department

Refining of fossil resin flotation concentrate from western coal. Final report

Description: During the past several years, significant research efforts have been made to develop process technology for the selective flotation of fossil resin from western coals. As a result of these efforts, several new flotation technologies have been developed. Operation of a proof-of-concept continuous flotation circuit showed the selective flotation process to be sufficiently profitable to justify the development of a fossil resin industry. However, little attention has been given to the refining of the fossil resin flotation concentrate although solvent refining is a critical step for the fossil resin to become a marketable product. In view of this situation, DOE funded this two-year project to evaluate the following aspects of the fossil resin refining technology: 1) Characterization of the fossil resin flotation concentrate and its refined products; 2) Kinetics of fossil resin extraction; 3) Effects of operating variables on solvent extraction; 4) Extraction solvents; 5) Proof-of-concept continuous refining tests; and 6) Technical and economic analysis. The results from this research effort have led to the following conclusions: Hexane- or heptane-refined fossil resin has a light-yellow color, a melting point of 140 - 142{degrees}C, a density of 1.034 gram/cm, and good solubility in nonpolar solvents. Among the four solvents evaluated (hexane, heptane, toluene and ethyl acetate), hexane is the most appropriate solvent based on overall technical and economic considerations. Batch extraction tests and kinetic studies suggest that the main interaction between the resin and the solvent is expected to be the forces associated with solvation phenomena. Temperature has the most significant effect on extraction rate. With hexane as the solvent, a recovery of 90% cam be achieved at 50{degrees}C and 10% solids concentration with moderate agitation for 1 hour.
Date: February 16, 1995
Creator: Jensen, G.F. & Miller, J.D.
Partner: UNT Libraries Government Documents Department

Fischer-tropsch synthesis in supercritical fluids. Quarterly technical progress report, October 1, 1994--December 21, 1994

Description: Progress reports are presented for the following two tasks: (1) diffusion coefficients of F-T products in supercritical fluids; and (2) Fischer-Tropsch reaction related studies. The objectives for this quarter for task 1 were to measure molecular diffusion coefficients and effective diffusivities at the same conditions. The objectives for task 2 were to conduct two additional tests with the Ruhrchemie catalyst and a catalyst synthesized in our laboratory under supercritical conditions.
Date: January 31, 1995
Creator: Akgerman, A. & Bukur, D.B.
Partner: UNT Libraries Government Documents Department

A GELATIN-FILTRATION HEADEND FOR FUEL REPROCESSING SOLUTIONS FROM SILICON- CONTAINING ALUMINUM ALLOYS

Description: A laboratory study of a gelatin headend process for feed from silicon- containing aluminum fuels and plant salvage solutions is described. The optimum conditions for the gelatin treatment of fuel solutions were to boil a 0.1 to 0.5N nitric acid solution with 100 milligrams of gelatin per liter for 30 minutes. This treatment improved filtration rates and decreased the surface activity of the filtrate for TBP extraction. A number of possible flowsheets for fuel solutions are presented using gelatin treatment and filtration. An adequate treatment was not found for salvage solutions of unknown composition because a gelatin dosage which was satisfactory for all solutions could not be selected. The optimum treatment for a salvage solution which was grossly contaminated with zirconium, soluble and colloidal silica, and dibutyl phosphate was to boil a 1N acid deficient solution with 600 milligrams of gelatin per liter, filter, and use a Hexone extraction system. A silicic colloid in fuel processing solutions was characterized as a surface active material by this study. (auth)
Date: February 1, 1959
Creator: Newby, B.J. & Paige, B.E.
Partner: UNT Libraries Government Documents Department

HYBRID SULFUR RECOVERY PROCESS FOR NATURAL GAS UPGRADING

Description: This first quarter report of 2001 describes progress on a project funded by the U.S. Department of Energy (DOE) to test a hybrid sulfur recovery process for natural gas upgrading. The process concept represents a low cost option for direct treatment of natural gas streams to remove H{sub 2}S in quantities equivalent to 0.2-25 metric tons (LT) of sulfur per day. This process is projected to have lower capital and operating costs than the competing technologies, amine/aqueous iron liquid redox and amine/Claus/tail gas treating, and have a smaller plant footprint, making it well suited to both on-shore and offshore applications. CrystaSulf (service mark of Gas Research Institute) is a new nonaqueous sulfur recovery process that removes hydrogen sulfide (H{sub 2}S) from gas streams and converts it into elemental sulfur. CrystaSulf features high sulfur recovery similar to aqueous-iron liquid redox sulfur recovery processes, but differs from the aqueous processes in that CrystaSulf controls the location where elemental sulfur particles are formed. In the hybrid process, approximately 1/3 of the total H{sub 2}S in the natural gas is first oxidized to SO{sub 2} at low temperatures over a heterogeneous catalyst. Low temperature oxidation is done so that the H{sub 2}S can be oxidized in the presence of methane and other hydrocarbons without oxidation of the hydrocarbons. The project involves the development of a catalyst using laboratory/bench-scale catalyst testing, and then demonstration of the catalyst at CrystaTech's pilot plant in west Texas. During this reporting period tests were done to determine the effect of hydrocarbons such as n-hexane on catalyst performance with and without H{sub 2}S present. The experiments showed that hexane oxidation is suppressed when H{sub 2}S is present. Hexane represents the most reactive of the C1 to C6 series of alkanes. Since hexane exhibits low reactivity under H{sub 2}S oxidation conditions, ...
Date: August 1, 2001
Creator: Srinivas, Girish; Gebhard, Steven C. & DeBerry, David W.
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

Description: The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Various chemicals that inhibit the growth and/or the metabolism of corrosion-associated microbes such as sulfate reducing bacteria, denitrifying bacteria, and methanogenic bacteria were evaluated to determine their ability to inhibit corrosion in experiments utilizing pure and mixed bacterial cultures, and planktonic cultures as well as mature biofilms. Planktonic cultures are easier to inhibit than mature biofilms but several compounds were shown to be effective in decreasing the amount of metal corrosion. Of the compounds tested hexane extracts of Capsicum pepper plants and molybdate were the most effective inhibitors of sulfate reducing bacteria, bismuth nitrate was the most effective inhibitor of nitrate reducing bacteria, and 4-((pyridine-2-yl)methylamino)benzoic acid (PMBA) was the most effective inhibitor of methanogenic bacteria. All of these compounds were demonstrated to minimize corrosion due to MIC, at least in some circumstances. The results obtained in this project are consistent with the hypothesis that any compound that disrupts the metabolism of any of the major microbial groups present in corrosion-associated biofilms shows promise in limiting the amount/rate of corrosion. This approach of controlling MIC by controlling the metabolism of biofilms is more environmentally benign than the current approach involving the use of potent biocides, and warrants further investigation.
Date: December 1, 2004
Creator: Bogan, Bill W.; Lamb, Brigid M.; Husmillo, Gemma; Lowe, Kristine; Paterek, J. Robert & II, John J. Kilbane
Partner: UNT Libraries Government Documents Department

AN ORIFICE PLATE PULSE COLUMN FOR LIQUID-LIQUID EXTRACTION (thesis)

Description: A study was made of the performance of an orifice plate pulse column which is essentially a spray column containing internal constrictions in the form of orifices. The chemical system studied was acetic acid-waterhexone, and the variables considered were pulse frequency, throughput, phase continuity, and direction of solute transfer. For comparison purposes, several runs were made with a conventional spray column. Curves are presented showing the effect of the column variables on the column efficiency (HTU). The trends observed are explained as being due principally to the competing effects of the area for mass transfer and back-mixing. Photographs of a typical column section show qualitatively the effect of the important column variables. (auth)
Date: August 23, 1954
Creator: O'Brien, D.C.
Partner: UNT Libraries Government Documents Department

PROCESS DEVELOPMENT QUARTERLY REPORT. II. PILOT PLANT WORK

Description: Progress is reported on the gross solubility of U in digestions of Mallinokrodt feed materials, studies of variables affecting U purity in a TBP hexane extraction cycle, low-acid flowsheet for TBP--hexane extraction process based on a 440 g U/liter in lM HNO/sub 3/ digest liquor, hacking studies in the pilot plant pumperdecanter system, recovery of U from residues from the dingot process, lowering the H level in dingot metal, forging of dingot bar stock, dingot extrusion, fubrication of UO/sub 2/ fuel elements, and the determination of H content of derby and ingot metal. (W.L.H.)
Date: May 1, 1957
Creator: Kuhlman, N. ed.
Partner: UNT Libraries Government Documents Department

Potential VOC Deflagrations in a Vented TRU Drum

Description: The objective of the analysis is to examine the potential for lid ejection from a vented transuranic (TRU) waste drum due to pressure buildup caused by the deflagration of hydrogen and volatile organic compounds (VOCs) inside the drum. In this analysis, the AICC pressure for a stoichiometric mixture of VOCs is calculated and then compared against the experimental peak pressure of stoichiometric combustion of propane and hexane in a combustion chamber. The experimental peak pressures of propane and hexane are about 12 percent lower than the calculated AICC pressure. Additional losses in the drum are calculated due to venting of the gases, drum bulging, waste compaction, and heat losses from the presence of waste in the drum. After accounting for these losses, the final pressures are compared to the minimum observed pressure that ejects the lid from a TRU drum. The ejection pressure of 105 psig is derived from data that was recorded for a series of tests where hydrogen-air mixtures were ignited inside sealed TRU drums. Since the calculated pressures are below the minimum lid ejection pressure, none of the VOCs and the hydrogen (up to 4 percent) mixtures present in the TRU waste drum is expected to cause lid ejection if ignited. The analysis of potential VOC deflagrations in a vented TRU drum can be applied across the DOE-Complex since TRU waste is stored in drums throughout the complex.
Date: April 7, 2005
Creator: Mukesh, GUPTA
Partner: UNT Libraries Government Documents Department

Solution Effects on Cesium Complexation with Calixarene - Crown Ethers from Liquid to Supercritical Fluids

Description: Supercritical fluid CO2 is an alternative solvent for extraction of metals. The solubility parameter of supercritical CO2 varies with density resembling that of liquid hexane at moderate pressures in the supercritical region to those of chlorinated solvents at very high pressures. By changing density of supercritical CO2, the solvation environment of a metal chelate system can vary continuously and resembles over a wide range of solvents. Thus, supercritical CO2 provides a unique system for studying solvation effects on metal chelation. This project is designed to investigate the solvation effects on cesium complexation with macrocyclic compounds including crown ethers and calixarene-crown ethers in CO2 from liquid to supercritical region at high pressures. A powerful spectroscopic technique for studying cesium chelation is nuclear magnetic resonance (NMR). Cesium has only one isotope, 133Cs, with a nuclear spin I = 7/2. Popov et al. used NMR to study cesium complexation with crown ethers and cryptand.
Date: June 1, 1999
Creator: Wai, Chien M. & Yonker,Clem
Partner: UNT Libraries Government Documents Department

Sensing liquid properties with shear-mode resonator sensors

Description: Liquid properties are measured from the changes they induce in the resonant frequency and damping of thicknessshear mode quartz resonators. A smooth-surfaced resonator viscously entrains the contacting fluid and responds to the density-viscosity product. Separation of density and viscosity is accomplished using two devices: one with a smooth surface and one with a corrugated surface that traps fluid. By observing the difference in stored and dissipated energies in the contacting fluid, its non-Newtonian characteristics can also be determined.
Date: June 1, 1995
Creator: Martin, S.J.; Cernosek, R.W. & Spates, J.J.
Partner: UNT Libraries Government Documents Department

Separation of Fischer-Tropsch wax from catalyst using supercritical fluid extraction. Quarterly technical progress report, April 1, 1996--June 30, 1996

Description: The objective of this research project is to evaluate the potential of SCF extraction for separating the catalyst slurry of a Fischer- Tropsch (F-T) slurry bubble column (SBC) reactor into two fractions: (1) a catalyst-free wax containing less than 10 ppm particulate matter and (2) a concentrated catalyst slurry that is ready for recycle or regeneration. The wax will be extracted with a hydrocarbon solvent that has a critical temperature near the operating temperature of the SBC reactor, i.e., 200-300{degrees}C. Initial work is being performed using n-hexane as the solvent. The success of the project depends on two major factors. First, the supercritical solvent must be able to dissolve the F-T wax; furthermore, this must be accomplished without entraining the solid catalyst. Second, the extraction must be controlled so as not to favor the removal of the low molecular weight wax compounds, i.e., a constant carbon-number distribution of the alkanes in the wax slurry must be maintained at steady-state column operation. To implement our objectives, the following task structure is being implemented: Task 1 equilibrium solubility measurements; Task 2 thermodynamic modeling; and Task 3 process design studies. Progress reports are presented for each task.
Date: November 1, 1996
Creator: Joyce, P.C. & Thies, M.C.
Partner: UNT Libraries Government Documents Department

Separation of Fischer-Tropsch wax from catalyst using supercritical fluid extraction. Quarterly technical progress report, 1 January 1996--31 March 1996

Description: The objective of this research project is to evaluate the potential of supercritical fluid extraction for separating the catalyst slurry of a Fischer-Tropsch (F-T) slurry bubble column (SBC) reactor into two fractions: (1) a catalyst-free wax containing less than 10 ppm particulate matter and (2) a concentrated catalyst slurry that is ready for recycle or regeneration. The wax will be extracted with a hydrocarbon solvent that has a critical temperature near the operating temperature of the SBC reactor, i.e., 200--300 {degrees}C. Initial work is being performed using n-hexane as the solvent. The success of the project depends on two major factors. First, the supercritical solvent must be able to dissolve the F-T wax; furthermore, this must be accomplished without entraining the solid catalyst. Second, the extraction must be controlled so as not to favor the removal of the low molecular weight wax compounds, i.e., a constant carbon-number distribution of the alkanes in the wax slurry must be maintained at steady-state column operation. During this quarter work focused on task 1b, experimental measurement of selected model systems. Vapor-liquid equilibrium experiments for the n- hexane/squalane system, which we initiated in the previous quarter, were continued and results are discussed in this report.
Date: September 1, 1996
Creator: Joyce, P.C. & Thies, M.C.
Partner: UNT Libraries Government Documents Department

Fischer Tropsch synthesis in supercritical fluids. Quarterly technical progress report, October 1--December 31, 1995

Description: Objectives for this quarter were to attempt to develop a model to predict the molecular diffusion coefficients to a high degree of accuracy so the authors may be able to predict both the molecular diffusion coefficient and thus the effective diffusivity a priori. They are working on a semi-empirical equation based on the rough hard sphere theory to predict diffusion coefficients in supercritical fluids. In addition, they planned to take additional data in order to extend the database available for development of the predictive equation. The paper discusses accomplishments and problems related to the diffusion coefficients of F-T products in supercritical fluids. Data are presented on the diffusion coefficients of 1-octene in ethane, propane, and hexane.
Date: June 1, 1996
Creator: Akgerman, A. & Bukur, D.B.
Partner: UNT Libraries Government Documents Department

Separation of Fischer-Tropsch wax from catalyst by supercritical extraction. Quarterly report, July 1, 1996 - September 30, 1996

Description: The objective of this research projects is to evaluate the potential of SCF extraction for separating the catalyst slurry of a Fischer- Tropsch (F-T) slurry bubble column (SBC) reactor into two fractions: (1) a catalyst-free wax containing less than 10 ppm particulate matter and (2) a concentrated catalyst slurry that is ready for recycle or regeneration. The wax will be extracted with a hydrocarbon solvent that has a critical temperature near the operating temperature of the SBC reactor, i.e. 200-300{degrees}C. Initial work is being performed using n-hexane as the solvent. The success of the projects depends on two major factors. First, the supercritical solvent must be able to dissolve the F-T wax; furthermore, the must be accomplished without entraining the solid catalyst. Second, the extraction must be controlled so as not to favor the removal of the low molecular weight wax compounds, i.e., a constant carbon-number distribution of the alkanes in the wax slurry must be maintained at steady-state column operation. The project includes three tasks (1) equilibrium solubility measurements, (2) thermodynamic modeling, and (3) process design studies.
Date: December 31, 1996
Creator: Joyce, P.C.; Thies, M.C.; Sherrard, D.; Biales, J.; Kilpatrick, P. & Roberts, G.
Partner: UNT Libraries Government Documents Department

IMPROVED ANTIFOAM AGENT STUDY END OF YEAR REPORT, EM PROJECT 3.2.3

Description: Antifoam 747 is added to minimize foam produced by process gases and water vapor during chemical processing of sludge in the Defense Waste Processing Facility (DWPF). This allows DWPF to maximize acid addition and evaporation rates to minimize the cycle time in the Chemical Processing Cell (CPC). Improvements in DWPF melt rate due to the addition of bubblers in the melter have resulted in the need for further reductions in cycle time in the CPC. This can only be accomplished with an effective antifoam agent. DWPF production was suspended on March 22, 2011 as the result of a Flammable Gas New Information/(NI) Potential Inadequacy in the Safety Analysis (PISA). The issue was that the DWPF melter offgas flammability strategy did not take into account the H and C in the antifoam, potentially flammable components, in the melter feed. It was also determined the DWPF was using much more antifoam than anticipated due to a combination of longer processing in the CPC due to high Hg, longer processing due to Actinide Removal Process (ARP)/Modular Caustic Side Solvent Extraction Unit (MCU) additions, and adding more antifoam than recommended. The resolution to the PISA involved and assessment of the impact of the antifoam on melter flammability and the implementation of a strategy to control additions within acceptable levels. This led to the need to minimize the use of Antifoam 747 in processing beginning in May 2011. DWPF has had limited success in using Antifoam 747 in caustic processing. Since starting up the ARP facility, the ARP product (similar chemically to caustic sludge) is added to the Sludge Receipt and Adjustment Tank (SRAT) at boiling and evaporated to maintain a constant SRAT volume. Although there is very little offgas generated during caustic boiling, there is a large volume of water vapor produced which can ...
Date: September 30, 2011
Creator: Lambert, D.; Koopman, D. & Newell, J.
Partner: UNT Libraries Government Documents Department