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Languages : en
Pages : 12
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The objective of this investigation is to determine the effects of SO2 partial pressure and reaction temperature on the conversion of sulfide containing solid wastes from coal gasifiers to stable and environmentally acceptable calcium-sulfate, while preventing the release of sulfur dioxide through undesirable side reactions during the stabilization step. An additional objective of this program is to investigate the use of the Spent Sorbent Regeneration Process (SSRP) to regenerate spent limestone, from a fluidized-bed gasifier with in-bed sulfur capture, for recycling to the gasifier. To achieve these objectives, selected samples of partially sulfided sorbents will be reacted with oxygen at a variety of operating conditions under sufficient SO2 partial pressure to prevent release of sulfur from the solids during stabilization that reduces the overall sorbent utilization. Partially sulfided limestone will also be regenerated with water to produce calcium hydroxide and release sulfur as H2S. The regenerated sorbent will be dewatered, dried and pelletized. The reactivity of the regenerated sorbent toward H2S will also be determined. During this quarter sulfidation tests were conducted in a quartz fluidized-bed reactor in which the selected calcium-based sorbents were first calcined and then were reacted with hydrogen sulfide at ambient pressure and 1650°F. These tests were conducted with each sorbent in two particle sizes. Chemical analyses of the partially sulfided sorbents indicate that the extent of sulfidation was in the range of 40--50%. The partially sulfided material will be reacted with oxygen to determine the effects of temperature and SO2 partial pressure on the stabilization of the calcium sulfide in solid waste materials. 23 refs., 1 fig., 2 tabs.
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Languages : en
Pages : 12
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The objective of this investigation is to determine the effects of SO2 partial pressure and reaction temperature on the conversion of sulfide containing solid wastes from coal gasifiers to stable and environmentally acceptable calcium-sulfate, while preventing the release of sulfur dioxide through undesirable side reactions during the stabilization step. An additional objective of this program is to investigate the use of the Spent Sorbent Regeneration Process (SSRP) to regenerate spent limestone, from a fluidized-bed gasifier with in-bed sulfur capture, for recycling to the gasifier. To achieve these objectives, selected samples of partially sulfided sorbents will be reacted with oxygen at a variety of operating conditions under sufficient SO2 partial pressure to prevent release of sulfur from the solids during stabilization that reduces the overall sorbent utilization. Partially sulfided limestone will also be regenerated with water to produce calcium hydroxide and release sulfur as H2S. The regenerated sorbent will be dewatered, dried and pelletized. The reactivity of the regenerated sorbent toward H2S will also be determined. During this quarter sulfidation tests were conducted in a quartz fluidized-bed reactor in which the selected calcium-based sorbents were first calcined and then were reacted with hydrogen sulfide at ambient pressure and 1650°F. These tests were conducted with each sorbent in two particle sizes. Chemical analyses of the partially sulfided sorbents indicate that the extent of sulfidation was in the range of 40--50%. The partially sulfided material will be reacted with oxygen to determine the effects of temperature and SO2 partial pressure on the stabilization of the calcium sulfide in solid waste materials. 23 refs., 1 fig., 2 tabs.
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Languages : en
Pages : 34
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The objective of this investigation was to determine the effects of SO2 partial pressure and reaction temperature on the conversion of sulfide containing solid wastes from coal gasifiers to stable and environmentally acceptable calcium sulfate, while preventing the release of sulfur dioxide during the stabilization step. An additional objective of this study was to investigate the use of the Spent Sorbent Regeneration Process (SSRP) to regenerate spent Ca-based sorbent, from a fluidized-bed gasifier with in-bed sulfur capture, for recycling to the gasifier. To achieve these objectives, selected samples of partially sulfided sorbents were reacted with oxygen and SO2 at various operating conditions and the extent of CaS and CaO conversion were determined. Partially sulfided dolomite was used in sulfidation/regeneration over several cycles and the regeneration efficiency and sorbent reactivity were determined after each cycle. The results of the stabilization tests show that partially sulfided Ca-based sorbents (both limestone and dolomite) can be sulfated at temperatures above 1500°F resulting in high CaS conversion without release of SO2 producing environmentally acceptable material for disposal in landfills. The results also indicate that spent dolomite can be regenerated in the SSRP process, in successive cycles, with high regeneration efficiency without loss of reactivity toward hydrogen sulfide.
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Languages : en
Pages : 18
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The overall objective of this study is to determine the effect of implementation of the new and more stringent EPA Protocol Test Method involving sulfide containing waste, on the suitability of the oxidized spent sorbents from gasification of of high sulfur coals for disposal in landfills, and to determine the optimum operating conditions in a ''final'' hydrolysis stage for conversion of the residual calcium sulfide in these wastes to materials that are suitable for disposal in landfills. An additional objective is to study the effect of ash on the regeneration and ash-sorbent separation steps in the Spent Sorbent Regeneration Process (SSRP). To achieve these objectives, a large set of oxidized samples of sulfided calcium-based sorbents (produced in earlier ICCI-funded programs) as well as oxidized samples of gasifier discharge (containing ash and spent sorbent) are tested according to the new EPA test protocol. Samples of the oxidized spent sorbents that do not pass the EPA procedure are reacted with water and carbon dioxide to convert the residual calcium sulfide to calcium carbonate. During this quarter, samples of oxidized sulfided calcium-based sorbents, including untreated calcium sulfide-containing feed materials, were analyzed using both weak acid and more stringent strong acid tests. Preliminary analysis of the H2S leachability test results indicate that all samples (including those that were not oxidized) pass the EPA requirement of 500 mg H2S per kg of solid waste. However, under the strong acid test procedure, samples containing more than 2.5% calcium sulfide fail the EPA requirement.
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Languages : en
Pages : 32
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The objective of this investigation was to determine the rates of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. To achieve this objective, samples of partially sulfided dolomite were reacted with oxygen at a variety of operating conditions in a fluidized-bed reactor. The effect of external diffusion was eliminated by using small quantities of the sorbent and maintaining a high flow rate of the reactant gas. The reacted sorbents were analyzed to determine the extent of conversion as a function of operating variables including sorbent particle size, reaction temperature and pressure, and oxygen concentration. The results of sulfation tests indicate that the rate of reaction increases with increasing temperature, increasing oxygen partial pressure, and decreasing sorbent particle size. The rate of the sulfation reaction can be described by a diffuse interface model where both chemical reaction and intraparticle diffusion control the reaction rate. The kinetic model of the sulfation reaction was used to determine the requirements for the reactor system, i.e., reactor size and operating conditions, for successful stabilization of sulfide-containing solid wastes from gasification of high sulfur coals (with in-bed desulfurization using calcium based sorbents). The results indicate that the rate of reaction is fast enough to allow essentially complete sulfation in reactors with acceptable dimensions. The optimum sulfation temperature appears to be around 800°C for high pressure as well as atmospheric stabilization of the spent sorbents.
![Stabilization of Spent Sorbents from Coal Gasification. [Quarterly] Technical Report, March 1--May 31, 1993 PDF](https://books.google.com/books/content/images/frontcover/uNSVAQAACAAJ?fife=w80-h100)
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Languages : en
Pages : 19
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The objective of this investigation is to determine the kinetics of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. During this quarter, samples of the partially sulfided dolomite were reacted with oxygen in the fluidized-bed reactor at different operating conditions. The test parameters included the effects of solid residence time, sorbent particle size, and reaction pressure. The reacted solids were analyzed to determine the extent of CaS conversion to CASO4. The results of these tests indicate that the rate of sulfation reaction increases with decreasing sorbent particle diameter and increasing pressure. Classical gas/solid reaction models, including the shrinking core model, the uniform conversion model, and the grainy pellet model, were applied to the experimental data of CaS sulfation. However, none of these models appears to be capable of predicting the measured CaS conversion with acceptable accuracy, indicating that these classical models should be modified to obtain better agreement between experimental and theoretical results.
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Languages : en
Pages : 15
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The objective of this investigation is to determine the kinetics of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. To achieve this objective, samples of partially sulfided dolomite are reacted with oxygen at a variety of operating conditions in a fluidized-bed reactor, where external diffusion limitations are avoided by using small quantities of the sorbent and maintaining a high flow rate of the reactant gas. The reacted sorbents are analyzed to determine the extent of conversion as a function of operating variables including sorbent particle size, reaction temperature and pressure, and oxygen concentration. Samples of the partially sulfided dolomite were reacted with oxygen in the fluidized-bed rector at different operating conditions. The test parameters included the effects of solid residence time, oxygen concentration, and reaction temperature. The reacted solids were analyzed to determine the extent of CaS conversion to CaSO4. The results of the tests conducted so far in the project indicate that the extent of conversion increase with increasing oxygen concentration and the solid residence time. The rate of reaction appears to be very sensitive to the reaction temperature.
Author: Aysel T. Atimtay
Publisher: Springer Science & Business Media
ISBN: 3642589774
Category : Technology & Engineering
Languages : en
Pages : 409
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Economic and environmental requirements for advanced power generating systems demand the removal of corrosive and other sulfurous compounds from hot coal gas. After a brief account of the world energy resources and an overview of clean coal technologies, a review of regenerable metal oxide sorbents for cleaning the hot gas is provided. Zinc oxide, copper oxide, calcium oxide, manganese oxide based as well as supported and mixed metal oxide sorbents are treated. Performance analysis of these sorbents, effects of various parameters on the desulfurization efficiency, kinetics of sulfidation and regeneration reactions, sulfiding and regeneration mechanisms are discussed. Two chapters present recent results in the direct production of elemental sulfur from regeneration or SO2-rich gases.
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Category : Power resources
Languages : en
Pages : 526
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Category :
Languages : en
Pages : 13
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The overall objective of this project is to obtain experimental data on the reactions of calcium-based sorbents applicable to both air-blown coal gasification systems and second generation fluid bed coal combustion systems (partial gasification). The project is a 40-month effort. A key technical issue for the utilization of calcium sorbents in advanced coal technologies is the subsequent stabilization of the solid wastes (calcium sulfide/ash) produced by such systems.
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Category :
Languages : en
Pages : 1738
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