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Description: The objective of this project is to develop a hot-gas desulfurization process scheme for control of H<sub>2</sub>S in HTHP coal gas that can be more simply and economically integrated with known regenerable sorbents in DOE/METC-sponsored work than current leading hot-gas desulfurization technologies. In addition to being more economical, the process scheme to be developed must yield an elemental sulfur byproduct. The Direct Sulfur Recovery Process (DSRP), a leading process for producing an elemental sulfur byproduct in hot-gas desulfurization systems, incurs a coal gas use penalty, because coal gas is required to reduce the SO<sub>2</sub> in regeneration off-gas to elemental sulfur. Alternative regeneration schemes, which avoid coal gas use and produce elemental sulfur, will be evaluated. These include (i) regeneration of sulfided sorbent using SO<sub>2</sub> ; (ii) partial oxidation of sulfided sorbent in an O<sub>2</sub> starved environment; and (iii) regeneration of sulfided sorbent using steam to produce H<sub>2</sub>S followed by direct oxidation of H<sub>2</sub>S to elemental sulfur. Known regenerable sorbents will be modified to improve the feasibility of the above alternative regeneration approaches. Performance characteristics of the modified sorbents and processes will be obtained through lab- and bench-scale testing. Technical and economic evaluation of the most promising processes concept(s) will be carried out.
Date: September 30, 1998
Partner: UNT Libraries Government Documents Department


Description: This research project examined the feasibility of a second generation high-temperature coal gas desulfurization process in which elemental sulfur is produced directly during the sorbent regeneration phase. Two concepts were evaluated experimentally. In the first, FeS was regenerated in a H2O-O2 mixture. Large fractions of the sulfur were liberated in elemental form when the H2O-O2 ratio was large. However, the mole percent of elemental sulfur in the product was always quite small (<<1%) and a process based on this concept was judged to be impractical because of the low temperature and high energy requirements associated with condensing the sulfur. The second concept involved desulfurization using CeO2 and regeneration of the sulfided sorbent, Ce2O2S, using SO2 to produce elemental sulfur directly. No significant side reactions were observed and the reaction was found to be quite rapid over the temperature range of 500°C to 700°C. Elemental sulfur concentrations (as S2) as large as 20 mol% were produced. Limitations associated with the cerium sorbent process are concentrated in the desulfurization phase. High temperature and highly reducing coal gas such as produced in the Shell gasification process are required if high sulfur removal efficiencies are to be achieved. For example, the equilibrium H2S concentration at 800°C from a Shell gas in contact with CeO2 is about 300 ppmv, well above the allowable IGCC specification. In this case, a two-stage desulfurization process using CeO2 for bulk H2S removal following by a zinc sorbent polishing step would be required. Under appropriate conditions, however, CeO2 can be reduced to non-stoichiometric CeOn (n<2) which has significantly greater affinity for H2S. Pre-breakthrough H2S concentrations in the range of 1 ppmv to 5 ppmv were measured in sulfidation tests using CeOn at 700°C in highly reducing gases, as measured by equilibrium O2 concentration, comparable to the Shell gas. Good sorbent ...
Date: October 31, 1998
Partner: UNT Libraries Government Documents Department

Bench-Scale Demonstration of Hot-Gas Desulfurization Technology

Description: The U.S. Department of Energy (DOE), Federal Energy Technology Center (FETC), is sponsoring research in advanced methods for controlling contaminants in hot coal gasifier gas (coal-derived fuel-gas) streams of integrated gasification combined-cycle (IGCC) power systems. The hot gas cleanup work seeks to eliminate the need for expensive heat recovery equipment, reduce efficiency losses due to quenching, and minimize wastewater treatment costs.
Date: December 1, 1998
Creator: Portzer, Jeffrey W. & Gangwal, Santosh K.
Partner: UNT Libraries Government Documents Department

Particulate Hot Gas Stream Cleanup Technical Issues

Description: This is the fifteenth quarterly report describing the activities performed under Contract No. DE-AC21-94MC31160. The analyses of Hot Gas Stream Cleanup (HGCU) ashes and descriptions of filter performance studied under this contract are designed to address problems with filter operation that are apparently linked to characteristics of the collected ash. Task 1 is designed to generate a data bank of the key characteristics of ashes collected from operating advanced particle filters (APFs) and to relate these ash properties to the operation and performance of these filters and their components. APF operations have also been limited by the strength and durability of the ceramic materials that have served as barrier filters for the capture of entrained HGCU ashes. Task 2 concerns testing and failure analyses of ceramic filter elements currently used in operating APFs and the characterization and evaluation of new ceramic materials. Task 1 research activities during the past quarter included characterizations of samples collected during a site visit on May 18 to the Department of Energy / Southern Company Services Power Systems Development Facility (PSDF) and a particulate sample collected in the Westinghouse filter at Sierra Pacific Power Company�s Piñon Pine Power Project. Analysis of this Piñon Pine sample is ongoing: however, this report contains the results of analyses completed to date. Significant accomplishments were achieved on the HGCU data bank during this reporting quarter. The data bank was prepared for presentation at the Advanced Coal-Based Power and Environmental Systems �98 Conference scheduled for July, 1998. Task 2 work during the past quarter consisted of testing two Dupont PRD-66C candle filters, one McDermott ceramic composite candle filter, one Blasch 4-270 candle filter, and one Specific Surface cordierite candle filter. Tensile and thermal expansion testing is complete and the rest of the testing is in progress. Also, some 20-inch long ...
Date: August 31, 1998
Partner: UNT Libraries Government Documents Department

Carbon Formation and Metal Dusting in Hot-Gas Cleanup Systems of Coal Gasifiers

Description: There are several possible materials/systems degradation modes that result from gasification environments with appreciable carbon activities. These processes, which are not necessarily mutually exclusive, include carbon deposition, carburization, metal dusting, and CO disintegration of refractories. Carbon formation on solid surfaces occurs by deposition from gases in which the carbon activity (a sub C) exceeds unity. The presence of a carbon layer CO can directly affect gasifier performance by restricting gas flow, particularly in the hot gas filter, creating debris (that may be deposited elsewhere in the system or that may cause erosive damage of downstream components), and/or changing the catalytic activity of surfaces.
Date: December 31, 1995
Creator: Tortorelli, Peter F.; Judkins, Roddie R.; DeVan, Jackson H. & Wright, Ian G.
Partner: UNT Libraries Government Documents Department

Fracture behavior of advanced ceramic hot-gas filters

Description: Microstructural, mechanical, and thermal-shock behavior of hot-gas candle filters obtained from different manufacturers have been evaluated. These filters include both monolithic ceramic and composite materials. Based on the results obtained so far, composite filters perform better than monolithic ceramic filters in a thermal-shock environment. During thermal-shock testing, the monolithic ceramic filters failed in a brittle (catastrophic) mode while composite filters showed a noncatastrophic mode of failure and very little degradation in ultimate strength. Fractographic evaluations were performed to identify and characterize critical flaws in Nextel fibers for the determination of in-situ fiber strength in Nextel/SiC filters. Average in--situ fiber strength was determined to be 1.7 GPa.
Date: May 1995
Creator: Singh, J. P.; Singh, D.; Smith, J. & Volz, H.
Partner: UNT Libraries Government Documents Department


Description: The overall objective of this project is the engineering development of a reusable calcium-based sorbent for desulfurizing hot coal gas. A two-step pelletization method has been employed to produce relatively strong, ''core-in-shell,'' spherical pellets. Each pellet consists of a highly reactive core surrounded by a strong, inert, porous shell. A suitable core is composed largely of CaO which reacts with H{sub 2}S to form CaS. Pellet cores have been prepared by pelletizing either pulverized limestone or plaster of Paris, and shells have been made of various materials. The most suitable shell material has been formed from a mixture of alumina and limestone particles. The core-in-shell pellets require treatment at high temperature to convert the core material to CaO and to partially sinter the shell material. Pellet cores derived from plaster of Paris have proved superior to those derived from limestone because they react more rapidly with H{sub 2}S and their reactivity does not seem to decline with repeated loading and regeneration. The rate of reaction of H{sub 2}S with CaO derived from either material is directly proportional to H{sub 2}S concentration. The rate of reaction does not appear to be affected significantly by temperature in the range of 1113 K (840 C) to 1193 K (920 C) but decreases markedly at 1233 K (960 C). The rate is not affected by shell thickness within the range tested, which also provides adequate compressive strength.
Date: June 30, 2001
Creator: Wheelock, T.D.; Doraiswamy, L.K. & Constant, K.
Partner: UNT Libraries Government Documents Department

Task 3.13 -- Hot-gas filter testing. Semi-annual report, January 1--June 30, 1995

Description: The objectives of the hot-gas cleanup (HGC) work on the transport reactor demonstration unit (TRDU) located at the Energy and Environmental Research Center (EERC) is to demonstrate acceptable performance of hot-gas filter elements in a pilot-scale system prior to long-term demonstration tests. The primary focus of the experimental effort in the 2-year project is the testing of hot-gas filter element performance (particulate collection efficiency, filter pressure differential, filter cleanability, and durability) as a function of temperature and filter face velocity during short-term operation (100--200 hours). This filter vessel is used in combination with the TRDU to evaluate the performance of selected hot-gas filter elements under gasification operating conditions. This work directly supports the power systems development facility (PSDF) utilizing the M.W. Kellogg transport reactor located at Wilsonville, Alabama and, indirectly, the Foster Wheeler advanced pressurized fluid-bed combustor, also located at Wilsonville.
Date: August 1, 1997
Creator: Mann, M.D.
Partner: UNT Libraries Government Documents Department


Description: This quarterly report describes technical activities performed under Contract No. DE-AC21-94MC31160. The analyses of hot gas stream cleanup (HGCU) ashes and descriptions of filter performance studied under Task 1 of this contract are designed to address problems with filter operation that are apparently linked to characteristics of the collected ash. This report reviews the status of the HGCU data bank of ash and char characteristics, including the interactive querying of measured particulate properties. Task 1 plans for the remainder of the project include completion and delivery of the HGCU data bank, and issuance of a comprehensive final report on activities conducted under Task 1. Task 2 of this project concerns the testing and failure analyses of new and used filter elements and filter materials. Task 2 work during the past quarter included preliminary testing of two materials. One material tested was the soft candle filter manufactured by CGC and supplied by ABB. The other material was N610/mullite manufactured by Albany International (AIT).
Date: August 30, 1999
Creator: Pontius, D.H.
Partner: UNT Libraries Government Documents Department

Particulate hot gas stream cleanup technical issues

Description: The analyses of hot gas stream cleanup particulate samples and descriptions of filter performance studied under this contract were designed to address problems with filter operation that have been linked to characteristics of the collected particulate matter. One objective of this work was to generate an interactive, computerized data bank of the key physical and chemical characteristics of ash and char collected from operating advanced particle filters and to relate these characteristics to the operation and performance of these filters. The interactive data bank summarizes analyses of over 160 ash and char samples from fifteen pressurized fluidized-bed combustion and gasification facilities utilizing high-temperature, high pressure barrier filters.
Date: September 30, 1999
Creator: Pontius, D.H. & Snyder, T.R.
Partner: UNT Libraries Government Documents Department

Engineering a new material for hot gas cleanup

Description: The engineering development of a promising sorbent for desulfurizing hot coal gas was initiated and preliminary results are presented. The sorbent is calcium-based and is designed to be regenerated and reused repeatedly. It is prepared by pelletizing powdered limestone in a rotating drum pelletizer followed by the application of a coating which becomes a strong, porous shell upon further treatment. The resulting spherical pellets combine the high reactivity of lime with the strength of an inert protective shell. Preliminary work indicates that a satisfactory shell material is comprised of a mixture of ultrafine alumina powder, somewhat coarser alumina particles, and pulverized limestone which upon heating to 1,373 K (1,100 C) becomes a coherent solid through the mechanism of particle sintering. Several batches of core-in-shell pellets were prepared and tested with encouraging results.
Date: March 1, 2000
Creator: Wheelock, T.D.; Doraiswamy, L.K. & Constant, K.
Partner: UNT Libraries Government Documents Department

Strength testing of hot gas filters: Volume 6. Final report

Description: The strength of various ceramic hot gas filter materials has been evaluated by four laboratories: Argonne National Laboratory, DuPont Lanxide, Southern Research Institute and Babcock and Wilcox. The filter materials under study include (a) a Nextel{trademark}/SiC composite filter (from 3M), (b) PRD-66, an all oxide layered microstructure of alumina, mullite, cordierite and some amorphous material by DuPont Lanxide, (c) a Babcock and Wilcox material consisting of an oxide composite of chopped fibers (Saffil) and continuous Nextel fibers, (d-f) monolithic and recrystallized SiC materials and an alumino/aluminosilicate material by IFPM, and (g) a monolithic SiC by the Pall Corporation. Not all four organizations tested each of the materials. PRD-66 was tested by three of the four. Four tests were used to evaluate properties of the candle filter materials. They included (a) the C-ring test, (b) the O-ring test, (c) the burst test and (d) the axial compression test. Each organization identified above did not perform all four tests. The objective of the study described here was to (a) provide an evaluation of the test methods used for hot gas filters to determine which is best for hot gas filter evaluation and (b) evaluate the discrepancies in results from tests run at different laboratories. No material ranking was made here, nor requested.
Date: June 9, 1998
Creator: Faber, K.T.
Partner: UNT Libraries Government Documents Department

Scale-Up of Advanced Hot-Gas Desulfurization Sorbents

Description: The overall objective of this project is to develop regenerable sorbents for hot gas desulfurization in IGCC systems. The specific objective of the project is to develop durable advanced sorbents that demonstrate a strong resistance to attrition and chemical deactivation, and high activity at temperatures as low as 343{degrees}C (650{degrees}F). A number of formulations will be prepared and screened in a 1/2-inch fixed bed reactor at high pressure (1 to 20 atm) and high temperatures using simulated coal-derived fuel-gases. Screening criteria will include, chemical reactivity, stability, and regenerability over the temperature range of 343{degrees}C to 650{degrees}C. After initial screening, at least 3 promising formulations will be tested for 25-30 cycles of absorption and regeneration. One of the superior formulations with the best cyclic performance will be selected for investigating scale up parameters. The scaled-up formulation will be tested for long term durability and chemical reactivity.
Date: April 21, 1997
Creator: Jothimurugesan, K. & Gangwal, S.K.
Partner: UNT Libraries Government Documents Department

Hot-gas filter manufacturing assessments: Volume 5. Final report, April 15, 1997

Description: The development of advanced filtration media for advanced fossil-fueled power generating systems is a critical step in meeting the performance and emissions requirements for these systems. While porous metal and ceramic candle-filters have been available for some time, the next generation of filters will include ceramic-matrix composites (CMCs), intermetallic alloys, and alternate filter geometries. The goal of this effort was to perform a cursory review of the manufacturing processes used by 5 companies developing advanced filters from the perspective of process repeatability and the ability for their processes to be scale-up to production volumes. It was found that all of the filter manufacturers had a solid understanding of the product development path. Given that these filters are largely developmental, significant additional work is necessary to understand the process-performance relationships and projecting manufacturing costs. While each organization had specific needs, some common among all of the filter manufacturers were access to performance testing of the filters to aide process/product development, a better understanding of the stresses the filters will see in service for use in structural design of the components, and a strong process sensitivity study to allow optimization of processing.
Date: December 31, 1997
Creator: Boss, D.E.
Partner: UNT Libraries Government Documents Department

Granular filtration in a fluidized bed

Description: Successful development of advanced coal-fired power conversion system often requires reliable and efficient cleanup devices that can remove particulate and gaseous pollutants from high-temperature, high- pressure gas streams. A novel filtration concept for particulate cleanup has been developed at the U.S. Department of Energy`s Morgantown Energy Technology Center (METC). The filtration system consists of a fine metal screen filter immersed in a fluidized bed of granular material. As the gas stream passes through the fluidized bed, a layer of the bed granular material is entrained and deposited at the screen surface. This material provides a natural granular filter to separate fine particles from the gas stream passing through the bed. Since the filtering media is the granular material supplied by the fluidized bed, the filter is not subjected to blinding like candle filters. Because only the in-flowing gas, not fine particle cohesive forces, maintains the granular layer at the screen surface, once the thickness and permeability of the granular layer are stabilized, it remains unchanged as long as the in-flowing gas flow rate remains constant. The weight of the particles and the turbulent nature of the fluidized bed limits the thickness of the granular layer on the filter leading to a self-cleaning attribute of the filter. The granular filtration testing system consisted of a filter, a two-dimensional fluidized bed, a continuous powder feeder, a laser-based, in-line particle counting, sizing, and velocimeter (PCSV), and a continuous solid feeding/bed material withdrawal system. The two-dimensional, transparent fluidized bed allowed clear observation of the general fluidized state of the granular material and the conditions under which fines are captured by the granular layer.
Date: December 31, 1996
Creator: Mei, J.S. & Yue, P.C.
Partner: UNT Libraries Government Documents Department

Advanced hot-gas filter development

Description: Coal is the most abundant fossil-fuel resource in the United States. `Clean coal` technologies, such as pressurized fluidized-bed combustion (PFBC) and integrated gasification combined-cycle (IGCC), require a hot gas filter to remove the corrosive and erosive coal ash entrained in the combustion gas stream. These hot gas filters, or candle filters, must be cost-effective while able to withstand the effects of corrosion, elevated temperature, thermal shock, and temperature transients. Ash loadings may range from 500 to 10,000 ppm by weight, and may contain particles as fine as 0.008 mils. The operating environment for the hot gas filter can range in pressure from 10 to 20 atm, in temperatures from 700 to 1750{degrees}F, and can be oxidizing or reducing. In addition, the process gases may contain volatile chloride, sulfur, and alkali species. Field testing of various commercially available, porous, ceramic filter matrices has demonstrated a loss of up to 50 percent of as-manufactured strength after 1,000 to 2,000 hours of exposure to these operating conditions, although full-scale elements have remained intact during normal process operations. Ultramet, a small business specializing in advanced materials R&D, has developed a new class of hot gas filter materials that offers lower back-pressure, higher permeability, longer life, and high filtration efficiency in the PFBC and IGCC environments. Subscale Ultrafoam Duplex Filter elements have undergone accelerated corrosion testing at temperatures of up to 2370{degrees}F (at Ultramet), and have been subjected to over 2,800 hours of exposure to hot PFBC gases (in the Westinghouse Advanced Particulate Filtration System at Brilliant, OH) without any loss in strength in either case. The Ultrafoam Duplex Filter matrix demonstrated 100 percent particle- capture efficiency of coal ash, and had an initial pressure drop of 0.1 to 0.6 in-wc/fpm. The Ultrafoam Duplex Filter is composed of a chemical vapor deposition (CVD), silicon carbide ...
Date: December 31, 1997
Creator: Stankiewicz, E.P.; Sherman, A.J. & Zinn, A.A.
Partner: UNT Libraries Government Documents Department

A new hot gas cleanup filter design methodology

Description: The fluid dynamics of Hot Gas Cleanup (HGCU) systems having complex geometrical configurations are typically analyzed using computational fluid dynamics codes (CFD) or bench-scale laboratory test facilities called cold-flow models (CFM). At the present time, both CFD and CFM can be effectively used for simple flows limited to one or two characteristic length scales with well defined boundary conditions. This is not the situation with HGCU devices. These devices have very complex geometries, low Reynolds number, multi-phase flows that operate on multiple-length scales. For this reason, both CFD and CFM analysis cannot yet be considered as a practical engineering analysis tool for modeling the entire flow field inside HGCU systems. The thrust of this work is to provide an aerodynamic analysis methodology that can be easily applied to the complex geometries characteristic of HGCU filter vessels, but would not require the tedious numerical solution to the entire set of transport equations. The analysis methodology performs the following tasks: Predicts problem areas where ash deposition will most likely occur; Predicts residence times for particles at various locations inside the filter vessel; Lends itself quickly to major design changes; Provides a sound technical basis for more appropriate use of CFD and CFM analysis; and Provides CFD and CFM analysis in a more focused way where if is needed.
Date: December 31, 1996
Creator: VanOsdol, J.G.; Dennis, R.A. & Shaffer, F.D.
Partner: UNT Libraries Government Documents Department


Description: Mixed manganese oxide sorbents have been investigated for high-temperature removal of hydrogen sulfide (the primary sulfur bearing compound) from hot coal gases. The sorbents were screened by thermodynamic equilibrium considerations for sulfidation. Preliminary experimental work using thermogravimetric analysis (TGA) indicated titania to be a superior substrate than alumina. Four formulations showing superior reactivity in a TGA were then tested in an ambient pressure fixed-bed reactor to determine steady state H 2 S concentrations, breakthrough times and effectiveness of the sorbent when subjected to cyclic sulfidation and regeneration testing. Eight tests were conducted with each test consisting of five cycles of sulfidation and regeneration. Sulfidation occurred at 600 o C using a simulated coal gas at an empty-bed space velocity of approximately 12,000 per hour. Manganese-based sorbents with molar ratios > 1:1 Mn:Substrate were effective in reducing the H 2 S concentration in simulated coal gases to less than 100 ppmv over five cycles. Actual breakthrough time for formulation C6-2-1100 was as high as 73% of breakthrough time based on wt% Mn in sorbent at 600 o C. Regeneration tests determined that loaded pellets can be essentially completely regenerated in an air/steam mixture at 750 o C with minimal sulfate formation. The leading formulation (designated C6-2) from the fixed-bed tests was then further tested under varying sorbent induration temperature, sulfidation temperature and superficial gas velocity. Four tests were conducted with each test consisting of four cycles of sulfidation and regeneration. Results showed that the induration temperature of the sorbent and the reaction temperature greatly affected the H 2 S removal capacity of the sorbent while the superficial gas velocity between 1090 and 1635 cm/min had minimal affect on the sorbent's breakthrough capacity. Testing showed that the sorbent's strength was a strong function of the sorbent induration temperature. Sorbent also showed 30 ...
Date: September 15, 1997
Partner: UNT Libraries Government Documents Department

Preliminary Strength Measurements of High Temperature Ash Filter Deposits

Description: The objective of this study is to develop and evaluate preliminary strength measurement techniques for high temperature candle filter ash deposits. The efficient performance of a high temperature gas filtering system is essential for many of the new thermal cycles being proposed for power plants of the future. These new cycles hold the promise of higher thermal efficiency and lower emissions of pollutants. Many of these cycles involve the combustion or gasification of coal to produce high temperature gases to eventually be used in gas turbines. These high temperature gases must be relatively free of particulates. Today, the candle filter appears to be the leading candidate for high temperature particulate removal. The performance of a candle filter depends on the ash deposits shattering into relatively large particles during the pulse cleaning (back flushing) of the filters. These relatively large particles fall into the ash hopper and are removed from the system. Therefore, these 1247 particles must be sufficiently large so that they will not be re-entrained by the gas flow. The shattering process is dictated by the strength characteristics of the ash deposits. Consequently, the objective of this research is to develop measurements for the desired strength characteristics of the ash deposits. Experimental procedures were developed to measure Young`s modulus of the ash deposit at room temperature and the failure tensile strain of ash deposits from room temperature to elevated temperatures. Preliminary data has been obtained for both soft and hard ash deposits. The qualifier ``preliminary`` is used to indicate that these measurements are a first for this material, and consequently, the measurement techniques are not perfected. In addition, the ash deposits tested are not necessarily uniform and further tests are needed in order to obtain meaningful average data.
Date: December 31, 1996
Creator: Kang, B.S.; Johnson, E.K.; Mallela, R. & Barberio, J.F.
Partner: UNT Libraries Government Documents Department

Advanced sulfur control concepts for hot gas desulfurization technology

Description: The objective of this project is to develop a hot-gas desulfurization process scheme for control of H{sub 2}S in HTHP coal gas that can be more simply and economically integrated with known regenerable sorbents in DOE/METC-sponsored work than current leading hot-gas desulfurization technologies. In addition to being more economical, the process scheme to be developed must yield an elemental sulfur byproduct.
Date: September 1, 1998
Partner: UNT Libraries Government Documents Department