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Irradiation-assisted stress corrosion cracking behavior of austenitic stainless steels applicable to LWR core internals.

Description: This report summarizes work performed at Argonne National Laboratory on irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels that were irradiated in the Halden reactor in simulation of irradiation-induced degradation of boiling water reactor (BWR) core internal components. Slow-strain-rate tensile tests in BWR-like oxidizing water were conducted on 27 austenitic stainless steel alloys that were irradiated at 288 C in helium to 0.4, 1.3, and 3.0 dpa. Fractographic analysis was conducted to determine the fracture surface morphology. Microchemical analysis by Auger electron spectroscopy was performed on BWR neutron absorber tubes to characterize grain-boundary segregation of important elements under BWR conditions. At 0.4 and 1.4 dpa, transgranular fracture was mixed with intergranular fracture. At 3 dpa, transgranular cracking was negligible, and fracture surface was either dominantly intergranular, as in field-cracked core internals, or dominantly ductile or mixed. This behavior indicates that percent intergranular stress corrosion cracking determined at {approx}3 dpa is a good measure of IASCC susceptibility. At {approx}1.4 dpa, a beneficial effect of a high concentration of Si (0.8-1.5 wt.%) was observed. At {approx}3 dpa, however, such effect was obscured by a deleterious effect of S. Excellent resistance to IASCC was observed up to {approx}3 dpa for eight heats of Types 304, 316, and 348 steel that contain very low concentrations of S. Susceptibility of Types 304 and 316 steels that contain >0.003 wt.% S increased drastically. This indicates that a sulfur related critical phenomenon plays an important role in IASCC. A sulfur content of <0.002 wt.% is the primary material factor necessary to ensure good resistance to IASCC. However, for Types 304L and 316L steel and their high-purity counterparts, a sulfur content of <0.002 wt.% alone is not a sufficient condition to ensure good resistance to IASCC. This is in distinct contrast to the behavior of their high-C ...
Date: January 31, 2006
Creator: Chung, H. M.; Shack, W. J. & Technology, Energy
Partner: UNT Libraries Government Documents Department

A modified release analysis procedure using advanced froth flotation mechanisms. Final technical report, September 1, 1995--August 31, 1996

Description: Recent studies indicate that the optimum separation performances achieved by multiple stage cleaning using various column flotation technologies and single stage cleaning using a Packed-Flotation Column are superior to the performance achieved by the traditional release procedure, especially in terms of pyritic sulfur rejection. This superior performance is believed to be the result of the advanced flotation mechanisms provided by column flotation technologies. Thus, the objective of this study was to develop a suitable process utilizing the advanced froth flotation mechanisms to characterize the true flotation response of a coal sample. This investigation resulted in the development of a modified coal flotation characterization procedure, termed as the Advanced Flotation Washability (AFW) technique. The apparatus used for this procedure is a batch operated Packed-Column device which provides enhanced selectivity due to a plug-flow environment and a deep froth zone. The separation performance achieved by the AFW procedure was found to be superior to those produced by the conventional tree and release procedures for three nominally -100 mesh coal samples and two micronized samples. The largest difference in separation performance was obtained on the basis of product pyritic sulfur content. A comparison conducted between the AFW and the release procedures at an 80% recovery value showed that the AFW technique provided a 19% improvement in the reduction of pyritic sulfur. For an Illinois No. 5 coal sample, this improvement corresponded to a reduction in pyritic sulfur content from 1.38% to 0.70% or a total rejection of 66%. Micronization of the sample improved the pyritic sulfur rejection to 85% while rejecting 92% of the ash-bearing material. In addition, the separation performance provided by the AFW procedure was superior to that obtained from multiple cleaning stages using a continuous Packed-Column under both kinetic and carrying-capacity limiting conditions.
Date: May 1, 1997
Creator: Honaker, R.Q. & Mohanty, M.K.
Partner: UNT Libraries Government Documents Department

The effect of potential upon the high-temperature fatigue crack growth response of low-alloy steels. Part 1: Crack growth results

Description: Corrosion-fatigue crack propagation experiments were conducted on several low-alloy steels in elevated temperature aqueous environments, and experimental parameters included temperature, sulfur content of the steel, applied potential level, and dissolved hydrogen (and in one case, dissolved oxygen) concentration in the water. Specimen potentials were controlled potentiostatically, and the observation (or non-observation) of accelerated fatigue crack growth rates was a complex function of the above parameters. Electrochemical results and the postulated explanation for the complex behavior are given in Part II.
Date: April 1, 1997
Creator: James, L.A. & Moshier, W.C.
Partner: UNT Libraries Government Documents Department

Back Contact Effects on the Electro-Optical Properties of CdTe/CdS Solar Cells

Description: Studies of junction photoluminescence (PL) in CdTe/CdS solar cells reveal that back-contact application produces a dramatic qualitative change in the junction picosecond-PL spectrum. Prior to contact application, the spectrum has two peaks at energies of 1.501 eV and 1.457 eV, corresponding to recombination in regions of CdTeS alloy with 2% and 12% sulfur content, respectively. After contact application, the spectrum consists of a single broad peak at 1.48 eV. Previous studies have shown that the nitric-phosphoric (NP) etch used in the contact procedure produces a layer of elemental tellurium (Te) on the CdTe surface. We postulate that the change in the near-junction PL spectrum is caused by a grain-boundary field effect due to perturbations of the grain-boundary conductivity and Fermi level.
Date: October 15, 1998
Creator: Levi, D. H.; Albin, D. S.; Gessert, T. A. (National Renewable Energy Laboratory) & Woods, L. M. (Department of Electrical Engineering, Colorado State University, Ft. Collins, CO)
Partner: UNT Libraries Government Documents Department

Reactive plasma upgrade of squalane - a heavy oil simulant

Description: U.S. light crude oil production has steadily declined over the last two decades. However, huge known heavy oil deposits in the North American continent remain largely untapped. In the past 10 years, the API gravity of crude oils has been decreasing by about 0.17% per year, and the sulfur content has been increasing by about 0.027% per year. As the API gravity of crude oil decreases, there will be an urgent need for economically viable new technologies to upgrade the heavy oil to a high API gravity feed stock for the refineries. The Idaho National Engineering Laboratory is investigating an innovative plasma process to upgrade heavy oil and refinery residuum. This paper will present some of the results and the implications of this technology for heavy oil upgrade and conversion.
Date: October 1, 1995
Creator: Kong, P.C.; Watkins, A.D.; Detering, B.A. & Thomas, C.P.
Partner: UNT Libraries Government Documents Department

Temperature and environmentally assisted cracking in low alloy steel

Description: Environmental assisted cracking (EAC) can be defined as the propagation of fatigue cracks in water at rates from 3 to over 40 times the growth rates in air. For low alloy steels with sulfur contents > 0.0125% by weight, EAC is normal behavior in the 240 to 290C range. However, literature yields mixed results for low alloy steels with compositions just below this sulfur level; some reports indicate EAC while others do not. Also, several authors have reported an increased tendency toward EAC when the water temperatures were lowered. In the present work, five ASTM A 508 Class 2 forgings with ladle and check analyses that ranged from 0.010 to 0.019 wt% S were tested in high purity deaerated water in the temperature range of 93 to 260C. At 260C these forgings did not exhibit EAC, reinforcing earlier results for two similar forgings. This broad sampling indicates strong resistance to EAC for this class of forging at 260C. On the other hand, EAC occurred consistently in the three of these forgings that were tested below 204C, provided the test conditions (loading frequency, {Delta}K, and R) were high enough to produce a high baseline fatigue crack growth rate (FCGR), where the baseline FCGR is that expected in air. At 149C, EAC occurred at test conditions that combined to yield a baseline FCGR greater than {approx}2E-6 mm/s. At 204, 121, and 93C, this critical crack growth rate appeared to shift to lower baseline values. The EAC that occurred at lower temperatures was a factor of 3 to 12 times higher than baseline air rates, which was not as strong as the effect for higher sulfur steels at 240 to 290C. Also, no plateau in the growth rates occurred as it does with the higher sulfur steels. In another approach, EAC was induced ...
Date: April 1, 1995
Creator: Auten, T.A. & Monter, J.V.
Partner: UNT Libraries Government Documents Department


Description: The technical objectives of this project are: (a) To identify the effect of the mode-of-occurrence of toxic elements in coal on the partitioning of these elements among vapor, submicron fume, and fly ash during the combustion of pulverized coal, (b) To identify the mechanisms governing the post-vaporization interaction of toxic elements and major minerals or unburnt char, (c) To determine the effect of combustion environment (i.e., fuel rich or fuel lean) on the partitioning of trace elements among vapor, submicron fume, and fly ash during the combustion of pulverized coal, (d) To model the partitioning of toxic elements among various chemical species in the vapor phase and between the vapor phase and complex aluminosilicate melts, (e) To develop the new Toxics Partitioning Engineering Model (ToPEM), applicable to all combustion conditions including new fuels and coal blends, low-NO{sub x} combustion systems, and new power generation plants. A description of the work plan for accomplishing these objectives is presented in Section 2.1 of this report. The work discussed in this report covers the reporting period from 1 October 1998 to 31 December 1998. During this quarter, basic coal testing at USGS was completed. Total sulfur contents range from 0.43 wt-% in the Wyodak to 2.68 wt-% in the Ohio sample. In the North Dakota and Ohio samples, about half of the total sulfur is pyritic and half is organic. The North Dakota sample also contains a minor amount of sulfate, consistent with the presence of barite in this sample. In the Wyodak sample, the majority of the sulfur is organic. Preliminary mineralogy of the three Phase II coals was determined by SEM/EDX. The Ohio coal contains all of the five most common major phases: quartz, illitic clay, kaolinitic clay, pyrite and calcite. Based on this preliminary work, the North Dakota sample appears ...
Date: January 28, 1999
Partner: UNT Libraries Government Documents Department

Bench-scale testing of the micronized magnetite process. Second quarterly technical progress report, October 1994--December 1994

Description: This document contains the Quarterly Technical Progress Report for the Micronized Magnetite Testing Project being performed at PETC`s Process Research Facility (PRF). This second quarterly report covers the period from October, 1994 through December, 1994. The main accomplishments of Custom Coals and the project subcontractors, during this period, included: (1) Submitted all overdue project documents and kept up with routine reporting requirements; (2) Worked with CLI Corporation, the design subcontractor, and completed the circuit design and finalized all design drawings; (3) Specified and procured all of the process equipment for the circuit, as well as a number of ancillary equipment, instruments, and supplies; (4) Assisted Vangura Iron Inc. in detailing and constructing the structural and platework steel; (5) Subcontracted Rizzo & Sons to perform the circuit mechanical and electrical installation, and prepared for January 23rd installation start date; (6) Organized and prepared for coal and magnetite procurement; (7) Specified and organized an operating personnel plan for the commissioning and testing tasks in the project; (8) Assessed analytical challenges for project, and began to research problem areas. This report contains a short discussion of the project description, objectives, budget, schedule, and teaming arrangement. It also includes a detailed discussion of the abovementioned project accomplishments and plans, organized by the various task series within the project work plan. The final section contains an outline of the specific project goals for the next quarterly reporting period.
Date: January 19, 1995
Partner: UNT Libraries Government Documents Department

Electrostatic beneficiation of coal. Quarterly technical progress report, April 1, 1996--June 30, 1996

Description: Progress reports are presented for the following: modification to the electrostatic separator; review of DOE specifications for minimum beneficiation and calculations of grinding requirements based on washability; two-pass beneficiation; analysis of different sieve fractions; measurement of charge to mass ratio as a function of height of deposition; and charging of coal against different materials.
Date: July 1, 1996
Creator: Mazumder, M.K.; Lindquist, D. & Tennal, K.B.
Partner: UNT Libraries Government Documents Department

Fouling formation of an olefin in the presence of oxygen and thiophenol

Description: A kinetic model was developed to predict the fouling rate for autoxidation of indene in the presence of thiophenol. The kinetic constants were determined by analyzing the fouling data obtained with and without thiophenol. An initial rapid formation of hydroperoxide was observed in the presence of thiophenol; however, the product(s) formed by thiophenol was found to inhibit further formation of hydroperoxide. The maximum concentration of hydroperoxide and gum were about the same for experiments with and without thiophenol; however, the maximum was reached faster for runs with thiophenol. The effects of bulk temperature, and concentration of thiophenol and oxygen on the fouling rate were analyzed using the fouling model developed previously.
Date: December 31, 1995
Creator: Yap, S.; Dranoff, J. & Panchal, C.B.
Partner: UNT Libraries Government Documents Department

Development of enhanced sulfur rejection processes. Final technical progress report, third quarter (8. quarterly report), July 1--September 30, 1994

Description: Pyrite becomes hydrophobic upon superficial oxidation and floats without a collector. The flotation begins to occur at potentials above the stable potentials identified by the chronoamperometry experiments conducted with freshly fractured pyrite. This finding suggests that iron polysulfide, formed during the initial stages of oxidation, is responsible for the flotation. The collectorless flotation is suppressed above the potential where the mineral is aggressively oxidized, forming iron hydroxide and soluble sulfoxy species. The collectorless flotation is less significant at pH 9.2 than at pH 4.6, possibly due to the formation of iron hydroxide. At pH 9.2, the collectorless flotation increases in the presence of EDTA and hydrocarbon oil. The collectorless flotation of pyrite can be suppressed by galvanically coupling the mineral with reactive metals such as aluminum, manganese, and zinc. This effectively prevents the mineral from oxidation. The microflotation tests conducted with mono-sized pyrite samples show that the collectorless flotation can be suppressed effectively in the presence of metal powders. Bench-scale flotation experiments conducted using Denver laboratory flotation cell and a 2-inch diameter Microcel flotation column, also demonstrates that the collectorless flotation can be suppressed in the presence of the reactive metals. It has been established that the most important parameters determining the effectiveness of suppressing pyrite flotation by the galvanic coupling technique are the surface area of the galvanic contractors and the solids concentration of the slurry during conditioning.
Date: March 20, 1996
Creator: Yoon, R.H.; Luttrell, G.H.; Tao, D.P.; Lu, M.X. & Richardson, P.E.
Partner: UNT Libraries Government Documents Department

Pilot scale single stage fine coal dewatering and briquetting process. Final technical report, September 1, 1995--August 31, 1996

Description: The primary goal of the ongoing ICCI coal preparation research project is to reduce ash and sulfur content in coal by using fine grinding and other coal cleaning processes. The ultrafine coal particles that result from the grinding and cleaning operations are difficult to dewater, and create problems in their storage, handling and transportation. The objective of this research is to combine the dewatering and briquetting processes of fine coal preparation into a single stage operation, thereby enhancing the economic viability of utilizing fine coal. A bitumen based emulsion, Orimulsion, has proven to be an effective hydrophobic binder, which helps not only with the briquetting process but also in the expulsion of water from the coal. Encouraging results from the use of a ram extruder briquetting device led to experimentation in the production of briquettes using a lab scale roll briquetting device. In the first quarter of this reporting year, a commercially available lab scale roll briquetting machine was employed (Komarek B-100). Further testing was conducted for the rest of the year with the use of a pilot scale model (Komarek B220-A). Briquettes were produced and evaluated by comparing results developed by adjusting various parameters of the briquetting machines and feed material. Results further substantiate previous findings that curing time dictates both moisture content and strengths of briquettes, and slower roll speeds produce more robust briquettes. A statistical model was set up to determine the optimal range of operating parameters. The statistical model generated from these results provided basic relationships between the roll speed and briquette form pressure.
Date: May 1, 1997
Creator: Wilson, J.W.; Honaker, R.Q. & Ding, Y.
Partner: UNT Libraries Government Documents Department

Task 4.4 - development of supercritical fluid extraction methods for the quantitation of sulfur forms in coal

Description: Development of advanced fuel forms depends on having reliable quantitative methods for their analysis. Determination of the true chemical forms of sulfur in coal is necessary to develop more effective methods to reduce sulfur content. Past work at the Energy & Environmental Research Center (EERC) indicates that sulfur chemistry has broad implications in combustion, gasification, pyrolysis, liquefaction, and coal-cleaning processes. Current analytical methods are inadequate for accurately measuring sulfur forms in coal. This task was concerned with developing methods to quantitate and identify major sulfur forms in coal based on direct measurement (as opposed to present techniques based on indirect measurement and difference values). The focus was on the forms that were least understood and for which the analytical methods have been the poorest, i.e., organic and elemental sulfur. Improved measurement techniques for sulfatic and pyritic sulfur also need to be developed. A secondary goal was to understand the interconversion of sulfur forms in coal during thermal processing. EERC has developed the first reliable analytical method for extracting and quantitating elemental sulfur from coal (1). This method has demonstrated that elemental sulfur can account for very little or as much as one-third of the so-called organic sulfur fraction. This method has disproved the generally accepted idea that elemental sulfur is associated with the organic fraction. A paper reporting the results obtained on this subject entitled {open_quote}Determination of Elemental Sulfur in Coal by Supercritical Fluid Extraction and Gas Chromatography with Atomic Emission Detection{close_quote} was published in Fuel (A).
Date: April 1, 1995
Creator: Timpe, R.C.
Partner: UNT Libraries Government Documents Department

Engineering development of advanced physical fine coal cleaning technologies - froth flotation. Quarterly technical progress report No. 23, April 1, 1994--June 30, 1994

Description: A study conducted by Pittsburgh Energy Technology Center of sulfur emissions from about 1,300 United States coal-fired utility boilers indicated that half of the emissions were the result of burning coals having greater than 1.2 pounds of SO{sub 2} per million BTU. This was mainly attributed to the high pyritic sulfur content of the boiler fuel. A significant reduction in SO{sub 2} emissions could be accomplished by removing the pyrite from the coals by advanced physical fine coal cleaning. An engineering development project was prepared to build upon the basic research effort conducted under a solicitation for research into Fine Coal Surface Control. The engineering development project is intended to use general plant design knowledge and conceptualize a plant to utilize advanced froth flotation technology to process coal and produce a product having maximum practical pyritic sulfur reduction consistent with maximum practical BTU recovery.
Date: April 1, 1995
Partner: UNT Libraries Government Documents Department

Tribological behavior of near-frictionless carbon coatings in high- and low-sulfur diesel fuels.

Description: The sulfur content in diesel fuel has a significant effect on diesel engine emissions, which are currently subject to environmental regulations. It has been observed that engine particulate and gaseous emissions are directly proportional to fuel sulfur content. With the introduction of low-sulfur fuels, significant reductions in emissions are expected. The process of sulfur reduction in petroleum-based diesel fuels also reduces the lubricity of the fuel, resulting in premature failure of fuel injectors. Thus, another means of preventing injector failures is needed for engines operating with low-sulfur diesel fuels. In this study, the authors evaluated a near-frictionless carbon (NFC) coating (developed at Argonne National Laboratory) as a possible solution to the problems associated with fuel injector failures in low-lubricity fuels. Tribological tests were conducted with NFC-coated and uncoated H13 and 52100 steels lubricated with high- and low- sulfur diesel fuels in a high-frequency reciprocating test machine. The test results showed that the NFC coatings reduced wear rates by a factor of 10 over those of uncoated steel surfaces. In low-sulfur diesel fuel, the reduction in wear rate was even greater (i.e., by a factor of 12 compared to that of uncoated test pairs), indicating that the NFC coating holds promise as a potential solution to wear problems associated with the use of low-lubricity diesel fuels.
Date: January 19, 2000
Creator: Alzoubi, M. F.; Ajayi, O. O.; Eryilmaz, O. L.; Ozturk, O.; Erdemir, A. & Fenske, G.
Partner: UNT Libraries Government Documents Department

Evaluation, engineering and development of advanced cyclone processes. Final separating media evaluation and test report (FSMER)

Description: {open_quotes}Evaluation Engineering and Development of Advanced Cyclone Processes{close_quotes} is one of the DOE-PETC sponsored advanced coal cleaning projects, which share a number of specific goals. These goals are to produce a 6% ash product, reject 85% of the parent coal`s pyritic sulfur, recover 85% of the parent coal`s Btu value, and provide products that are less than 30% moisture. The process in this project, as the name implies, relies on a cyclone or cyclonic separator to achieve physical beneficiation based on the gravimetric differences between clean coal and its impurities. Just as important as the cyclonic separator, if not more so, is the selection of a parting liquid or medium for use in the separator. Selection of a separating medium is regarded as a significant portion of the project because it has a profound impact on the required unit operations, the performance of the separator, and economics of the process. The choice of medium especially influences selection of media recovery system(s), and the characteristics of clean coal and refuse products. Since medium selection is such an important aspect of the project, portions of the project are dedicated to the study, evaluation, and selection of the most desirable medium. Though separators are an important component, this project initially focused on media study, rather than the separators themselves. In coal processing, discussion of media requires description of the handling and recovery system(s), separation performance, interaction with coal, cost, and health, environmental and safety issues. In order to be effective, a candidate must perform well in all of these categories.
Date: May 19, 1995
Partner: UNT Libraries Government Documents Department

Development of a Coal Quality Expert

Description: ABB Power Plant Laboratories Combustion Engineering, Inc., (ABB CE) and CQ Inc. completed a broad, comprehensive program to demonstrate the economic and environmental benefits of using higher quality U.S. coals for electrical power generation and developed state-of-the-art user-friendly software--Coal Quality Expert (CQE)-to reliably predict/estimate these benefits in a consistent manner. The program was an essential extension and integration of R and D projects performed in the past under U.S. DOE and EPRI sponsorship and it expanded the available database of coal quality and power plant performance information. This software will permit utilities to purchase the lowest cost clean coals tailored to their specific requirements. Based on common interest and mutual benefit, the subject program was cosponsored by the U.S. DOE, EPRI, and eight U.S. coal-burning utilities. In addition to cosponsoring this program, EPN contributed its background research, data, and computer models, and managed some other supporting contracts under the terms of a project agreement established between CQ Inc. and EPRI. The essential work of the proposed project was performed under separate contracts to CQ Inc. by Electric Power Technologies (El?'T), Black and Veatch (B and V), ABB Combustion Engineering, Babcock and Wilcox (B and W), and Decision Focus, Inc. Although a significant quantity of the coals tied in the United States are now cleaned to some degree before firing, for many of these coals the residual sulfur content requires users to install expensive sulfur removal systems and the residual ash causes boilers to operate inefficiently and to require frequent maintenance. Disposal of the large quantities of slag and ash at utility plant sites can also be problematic and expensive. Improved and advanced coal cleaning processes can reduce the sulfur content of many coals to levels conforming to environmental standards without requiring post-combustion desulfurization systems. Also, some coals may be beneficiated ...
Date: June 20, 1998
Partner: UNT Libraries Government Documents Department

Molten-Caustic-Leaching (Gravimelt) System Integration Project. Quarterly report, July--September 1989

Description: Operation of the Gravimelt Integrated Test Circuit for desulfurization and demineralization of coal has been completed. A 48-test process matrix was performed over 750 hours of operational time resulting in production of 3,000 pounds of treated coal suitable for further test and evaluation. Analysis of the several thousand data is underway. Assessment of coal material balance data shows an average 98% closure with 2% conversion of coal to humics and phenolics, 3% conversion to hydrogen and methane and 3 1/2% loss as carbonate. Assessment of sulfur forms data shows a mean residual pyritic sulfur of 0.022% for Pittsburgh No. 8 seam coal and 0.01% for Kentucky No. 9. Organic sulfur removal was dependent on conditions with lowest at 0.08% after processing in the plant. The mean sulfate sulfur level was 0.28% with a standard deviation of only 0.06%.
Date: October 10, 1989
Partner: UNT Libraries Government Documents Department

Ohio Coal Testing and Development Facility - Construction and operation. Final report

Description: On June 14, 1987, the Ohio Coal Development Office (OCDO) executed a grant agreement with ICF Kaiser Engineers (ICF Kaiser) for the planning and design (Phase I) of a Demonstration Advanced Technology Coal Preparation Facility. Subsequently, on December 1, 1990, OCDO executed a grant agreement with the American Electric Power Service Corporation (AEPSC) through its subsidiary, the Ohio Power Company, for the final design and construction (Phase II), testing and operation (Phase III), and marketing and future operation (Phase IV) of the facility. These phases were subcontracted to ICF Kaiser. AEPSC co-sponsored the project and donated a site at the Central Ohio Coal Company`s Unionville Coal Preparation Plant for locating the test plant. Central Ohio Coal supplied coal handling services, waste-product disposal, and water. The Ohio Power Company provided project oversight, electric power, and the test coals. The test results from the operation of the 30 tph advanced coal cleaning plant demonstrated that combining conventional physical coal cleaning with emerging advanced physical coal cleaning technologies was a cost-effective method to reduce sulfur emissions of Ohio coals. The following is a summary of the key findings of this project.
Date: March 1, 1996
Creator: Ferris, D.D.
Partner: UNT Libraries Government Documents Department


Description: Calcium oxide injected in a slagging combustor reacts with the sulfur from coal combustion to form sulfur-bearing particles. They are deposited on the liquid slag layer on the combustor wall. Due to the low solubility of sulfur in slag, slag must be rapidly drained from the combustor to limit sulfur gas re-evolution. Analysis indicated that slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 42-month project was to perform a series of tests to determine the factors that control the retention of the sulfur in the slag. 36 days of testing on the combustor were completed prior to the end of this reporting period, 12/31/98. This compares with 16 tests required in the original project plan. Combustor tests in early 1997 with high (37%) ash, Indian coal confirmed that high slag mass flow rates of about 500 lb/hr resulted in retention in the slag of up to 20% of the injected sulfur content mineral matter. To further increase the slag flow rate, rice husks, which contain 20% ash, and rice husk char, which contain 70% ash, were co-fired with coal in the combustor. A series of 13 combustor tests were performed in fourth quarter of 1997 and a further 6 tests were performed in January 1998 and in the summer of 1998. The test objective was to achieve slag flow rates between 500 and 1,000 lb/hr. Due to the very low bulk density of rice husk, compared to pulverized coal, almost the entire test effort focused on developing methods for feeding the rice husks into combustor. In the last test of December 1997, a peak mineral matter, injection rate of 592 lb/hr was briefly achieved by injection of coal, rice husk char, gypsum, and limestone into the combustor. However, no significant sulfur ...
Date: March 15, 1999
Creator: Zauderer, Dr. Bert
Partner: UNT Libraries Government Documents Department

Production Scale-Up or Activated Carbons for Ultracapacitors

Description: Transportation use accounts for 67% of the petroleum consumption in the US. Electric and hybrid vehicles are promising technologies for decreasing our dependence on petroleum, and this is the objective of the FreedomCAR & Vehicle Technologies Program. Inexpensive and efficient energy storage devices are needed for electric and hybrid vehicle to be economically viable, and ultracapacitors are a leading energy storage technology being investigated by the FreedomCAR program. The most important parameter in determining the power and energy density of a carbon-based ultracapacitor is the amount of surface area accessible to the electrolyte, which is primarily determined by the pore size distribution. The major problems with current carbons are that their pore size distribution is not optimized for liquid electrolytes and the best carbons are very expensive. TDA Research, Inc. (TDA) has developed methods to prepare porous carbons with tunable pore size distributions from inexpensive carbohydrate based precursors. The use of low-cost feedstocks and processing steps greatly lowers the production costs. During this project with the assistance of Maxwell Technologies, we found that an impurity was limiting the performance of our carbon and the major impurity found was sulfur. A new carbon with low sulfur content was made and found that the performance of the carbon was greatly improved. We also scaled-up the process to pre-production levels and we are currently able to produce 0.25 tons/year of activated carbon. We could easily double this amount by purchasing a second rotary kiln. More importantly, we are working with MeadWestvaco on a Joint Development Agreement to scale-up the process to produce hundreds of tons of high quality, inexpensive carbon per year based on our processes.
Date: January 10, 2007
Creator: Dietz, Dr. Steven D.
Partner: UNT Libraries Government Documents Department

Comments on cathode contaminants and the LBNL test stand

Description: This report collects information on cathode contaminants we have gathered in the process of operating the LBNL DARHT cathode test stand. Information on contaminants is compiled from several sources. The attachment, ''Practical Aspects of Modern Dispenser Cathodes'', is from Heat Wave Corp. (TB-134) and was originally published in Microwave Journal, September 1979. Cathode contamination depends on both material choices and residual gases. Table 1 of TB-134 lists materials that can poison dispenser cathodes. These include reactive residual gases or vapors such as oxygen, water vapor, benzene, chlorine, fluorine, sulfur, silicon, and most metals other than molybdenum, rhenium, tungsten, and copper. The metals interact with the cathode surface through their vapor pressure. A paper by Nexsen and Turner, J. Appl. Phys. 68, 298-303 (1990) shows the threshold effects of some common residual gases or vapors on cathode performance. The book by Walter H. Kohl, Handbook of Materials and Techniques for Vacuum Devices, also contains useful information on cathodes and poisoning agents. A plot of the vapor pressures and poisoning effect of certain metals (from Kohl) is shown below. Note that the vapor pressure of zinc is 1.1 x 10{sup -8} Torr at 400 K = 127 C, and 2.7 x 10{sup -5} at 500 K = 227 C. By contrast iron reaches a vapor pressure 1 x 10{sup -8} between 800 and 900 C. Therefore it is important to eliminate any brass parts that could exceed a temperature of 100 C. Many structural components of the cathode assembly contain steel. At 500-600 C in an oxygen atmosphere chromium oxide may outgas from the steel. [Cho, et.al., J. Vac. Sci. Technol. A 19, p. 998 (2001)]. Steel may also contain silicon, and sulfur at low concentrations. Therefore use of steel should be limited or avoided at high temperature near the cathode. Materials ...
Date: November 13, 2006
Creator: Bieniosek, F.; Baca, D.; Greenway, W.; Leitner, M. & Kwan, J.W.
Partner: UNT Libraries Government Documents Department