Durable Zinc Oxide-Based Regenerable Sorbents for Desulfurization of Syngas in a Fixed-Bed Reactor PDF Download
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Languages : en
Pages : 13
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A fixed-bed regenerable desulfurization sorbent, identified as RVS-1 and developed by researchers at the U.S. Department of Energy's National Energy Technology Laboratory, was awarded the R & D 100 award in 2000 and is currently offered as a commercial product by Sued- Chemie Inc. An extensive testing program for this sorbent was undertaken which included tests at a wide range of temperatures, pressures and gas compositions both simulated and generated in an actual gasifier for sulfidation and regeneration. During these desulfurization tests, the RVS-1 sorbent maintained an effluent H2S concentration of 5 ppmv at temperatures from 260 to 600 C (500-1100 F) and pressures of 203-2026 kPa(2 to 20 atm) with a feed containing 1.2 vol% H2S. The types of syngas tested ranged from an oxygen-blown Texaco gasifier to biomass-generated syngas. The RVS-1 sorbent has demonstrated high crush strength and attrition resistance, which, unlike past sorbent formulations, does not decrease with extended testing at actual operating conditions. The sulfur capacity of the sorbent is roughly 17 to 20 wt.% which has been shown to remain constant during extended testing (25 cycles). In addition to H2S, the RVS-1 sorbent has also demonstrated the ability to remove dimethyl sulfide and carbonyl sulfide from syngas. It was also possible to obtain sulfur levels in the parts per billion by volume range with the modified RVS-1 sorbent. During regeneration, the RVS-1 sorbent has been regenerated with dilute oxygen streams (1 to 7 vol% O2) at temperatures as low as 370 C (700 F) and pressures of 304-709 kPa(3 to 7 atm). Although regeneration can be initiated at 370 C (700 F), regeneration temperatures in excess of 538 C (1000 F) were found to be optimal. The presence of steam, carbon dioxide or sulfur dioxide (up to 6 vol%) did not have any visible effect on regeneration or sorbent performance during either sulfidation or regeneration.
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Languages : en
Pages : 13
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Book Description
A fixed-bed regenerable desulfurization sorbent, identified as RVS-1 and developed by researchers at the U.S. Department of Energy's National Energy Technology Laboratory, was awarded the R & D 100 award in 2000 and is currently offered as a commercial product by Sued- Chemie Inc. An extensive testing program for this sorbent was undertaken which included tests at a wide range of temperatures, pressures and gas compositions both simulated and generated in an actual gasifier for sulfidation and regeneration. During these desulfurization tests, the RVS-1 sorbent maintained an effluent H2S concentration of 5 ppmv at temperatures from 260 to 600 C (500-1100 F) and pressures of 203-2026 kPa(2 to 20 atm) with a feed containing 1.2 vol% H2S. The types of syngas tested ranged from an oxygen-blown Texaco gasifier to biomass-generated syngas. The RVS-1 sorbent has demonstrated high crush strength and attrition resistance, which, unlike past sorbent formulations, does not decrease with extended testing at actual operating conditions. The sulfur capacity of the sorbent is roughly 17 to 20 wt.% which has been shown to remain constant during extended testing (25 cycles). In addition to H2S, the RVS-1 sorbent has also demonstrated the ability to remove dimethyl sulfide and carbonyl sulfide from syngas. It was also possible to obtain sulfur levels in the parts per billion by volume range with the modified RVS-1 sorbent. During regeneration, the RVS-1 sorbent has been regenerated with dilute oxygen streams (1 to 7 vol% O2) at temperatures as low as 370 C (700 F) and pressures of 304-709 kPa(3 to 7 atm). Although regeneration can be initiated at 370 C (700 F), regeneration temperatures in excess of 538 C (1000 F) were found to be optimal. The presence of steam, carbon dioxide or sulfur dioxide (up to 6 vol%) did not have any visible effect on regeneration or sorbent performance during either sulfidation or regeneration.
Author: Ranjani V. Siriwardane
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Category : Chemical engineering
Languages : en
Pages : 9
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Category :
Languages : en
Pages : 75
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Category :
Languages : en
Pages : 10
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The US Department of Energy is currently developing Integrated Gasification combined Cycle (IGCC) systems for electrical power generation. It has been predicted that IGCC plants with hot gas cleanup will be superior to conventional pulverized coal-fired power plants in overall plant efficiency and environmental performance. Development of a suitable regenerable sorbent is a major barrier issue in the hot gas cleanup program for IGCC systems. This has been a challenging problem during the last 20 years, since many of the sorbents developed in the program could not retain their reactivity and physical integrity during repeated cycles of sulfidation and regeneration reactions. Two promising sorbents and (METC6), which were capable of sustaining their reactivity and physical integrity during repeated sulfidation/regeneration cycles, have been developed at the Morgantown Energy Technology Center (METC) during the past year. These sorbents were tested (sulfided) both in low-pressure (260 kPa/37.7 psia) and high-pressure (1034 kPa/150 psia) fixed-bed reactors at 538°C (1000°F) with simulated KRW coal gas. High-pressure testing was continued for 20 cycles with steam regeneration. There were no appreciable changes in sulfidation capacity of the sorbents during the 20-cycle testing. The crush strength of the sorbent actually improved after 20 cycles and there were no indications of spalling or any other physical deterioration of the sorbents. In testing to date, these sorbents exhibit better overall sulfur capture performance than the conventional sorbents.
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Category :
Languages : en
Pages : 5
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The objective of this study is to develop hot-gas cleanup sorbents for relatively lower temperature application, with emphasis on the temperature applications, with emphasis on the temperature range from 343--538 C.A number of formulations will be prepared and screened for testing 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 C to 538 C. Each formulation will be tested for up to 5 cycles of absorption and regeneration. To prevent sulfation, catalyst additives will be investigated, which would promote a lower ignition of the regeneration. Selected superior formulation will be tested for long term (up to at least 30 cycles) durability and chemical reactivity in the reactor. Zinc oxide based sorbents were prepared and characterized as fresh, sulfided, and regenerated sorbents. Results are presented.
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Category :
Languages : en
Pages : 5
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Primary issues for the fluidized-bed/transport reactor process are high attrition resistant sorbent, its high sorption capacity and regenerability, durability, and cost. The overall objective of this project is the development of a superior attrition resistant zinc oxide-based sorbent for hot gas cleanup in integrated coal gasification combined cycle (IGCC). Sorbents applicable to a fluidized-bed hot gas desulfurization process must have a high attrition resistance to withstand the fast solid circulation between a desulfurizer and a regenerator, fast kinetic reactions, and high sulfur sorption capacity. The oxidative regeneration of zinc-based sorbent usually initiated at greater than 600 C with highly exothermic nature causing deactivation of sorbent as well as complication of sulfidation process by side reaction. Focusing on solving the sorbent attrition and regenerability of zinc oxide-based sorbent, we have adapted multi-binder matrices and direct incorporation of regeneration promoter. The sorbent forming was done with a spray drying technique that is easily scalable to commercial quantity.
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Category :
Languages : en
Pages : 10
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The objectives of this project are to identify and demonstrate methods for enhancing long-term chemical reactivity and attrition resistance of zinc oxide-based mixed metal-oxide sorbents for desulfurization of hot coal-derived gases in a high-temperature, high-pressure (HTHP) fluidized-bed reactor. In this program, regenerable ZnO-based mixed metal-oxide sorbents are being developed and tested. These include zinc ferrite, zinc titanate, and Z-SORB sorbents. The Z-SORB sorbent is a proprietary sorbent developed by Phillips Petroleum Company (PPCo).
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Category :
Languages : en
Pages : 8
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The overall objective of this project is to develop regenerable sorbents for hot gas desulfurization in IGCC systems. The major criteria for the development of novel sorbents included reasonable chemical reactivity and physical durability during repeated sulfidation and regeneration cycles. Various formulations of zinc ferrite and zinc titanate in the form of extrudates and spherical pellets have been studied at the Morgantown Energy Technology Center (METC) for removal of sulfurous gases from coal gasification gas streams. Problems of decrepitation and spalling have occurred after sulfidation and regeneration of these sorbents. Z-Sorb, a proprietary sorbent developed at Phillips Petroleum Company, showed good physical durability during testing at METC, but there was a continuous decrease in reactivity during multiple cycle tests due to steam regeneration. A series of novel sorbents containing zinc oxide have been developed at METC to address these problems. These METC-developed sorbents showed superior performance during a 20-cycle, high-pressure, fixed-bed test with steam regeneration conducted at METC. Nine sorbents were prepared, but results are given for only three.
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Category :
Languages : en
Pages : 8
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Integrated gasification combined cycle (IGCC) power systems are being advanced worldwide for generating electricity from coal due to their superior environmental performance, economics, and efficiency in comparison to conventional coal-based power plants. Hot gas cleanup offers the potential for higher plant thermal efficiencies and lower cost. A key subsystem of hot-gas cleanup is hot-gas desulfurization using regenerable sorbents. Sorbents based on zinc oxide are currently the leading candidates and are being developed for moving- and fluidized- bed reactor applications. Zinc oxide sorbents can effectively reduce the H2S in coal gas to around 10 ppm levels and can be regenerated for multicycle operation. However, all current first-generation leading sorbents undergo significant loss of reactivity with cycling, as much as 50% or greater loss in only 25-50 cycles. Stability of the hot-gas desulfurization sorbent over 100's of cycles is essential for improved IGCC economics over conventional power plants. This project aims to develop hot-gas cleanup sorbents for relatively lower temperature applications, 343 to 538°C with emphasis on the temperature range from 400 to 500°. Recent economic evaluations have indicated that the thermal efficiency of IGCC systems increases rapidly with the temperature of hot-gas cleanup up to 350°C and then very slowly as the temperature is increased further. This suggests that the temperature severity of the hot-gas cleanup devices can be reduced without significant loss of thermal efficiency. The objective of this study is to develop attrition-resistant advanced hot-gas desulfurization sorbents which show stable and high sulfidation reactivity at 343°C (650°F) to 538°C(1OOO°F) and regenerability at lower temperatures than leading first generation sorbents.
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Category : Power resources
Languages : en
Pages : 544
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