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mixed-feedstock gasification for syngas production
08 Steam raising (boiler operation~design) 02/02101 Removal of organic chlorine compounds by catalytic dehydrochlorination for the refinement of municipal waste plastic derived oil Lingaiah, N. et al. Fuel, 2001, 80, (13), 1901-1905. Municipal waste plastic derived oil was prepared by thermal degradation of municipal waste plastics at 410°C. During the degradation of these waste plastics containing polyvinyl chloride, organic chlorine compounds were produced in the oil. The chloro-organic compounds were dehydrochlorinated by using various catalysts such as iron oxide, iron oxide-carbon composite, ZnO, MgO and Redmud. The catalysts were characterized by N2 adsorption and X-ray diffraction. The iron oxide catalysts were effective in removing the chloro-organic compounds. MgO and ZnO catalysts were deactivated during the reaction by HCI, which is produced by the dehydrochlorination of chloroorganic compounds. Iron oxide and its carbon composite were found to be stable in the dehydrochlorination of municipal waste plastic derived oil.
02/02102 The renewable portfolio standard: design considerations and an implementation survey Berry, T. and Jaccard, M. Energy Policy, 2001, 29, (4), 263-277. Renewables have social and environmental benefits compared to conventional electricity sources, but are rarely competitive on a strict financial cost basis. This is because conventional sources are sometimes subsidized, their full pollution costs are ignored, and renewables involve newer, higher-cost technologies whose relative costs will fall with commercialization. Governments use several mechanisms to support renewables, including direct financial support (grants, loans), indirect support (R&D, demonstrations), reform of financial costs of conventional sources (subsidy removal, pollution taxes), and the Renewable Portfolio Standard (RPS). The RPS requires a minimum share of electricity from renewable energy sources. Its use is spreading because it maintains an incentive for renewable producers to reduce cost, links the regulated market outcome to an environmental target, and reduces government involvement. Although it is too early to evaluate fully its effectiveness, the survey for this study explored implementation issues in three European countries, nine US states, and Australia, and found the following. The RPS target is usually set to have environmental benefits without causing significant price increases (cost caps are sometimes used). Most jurisdictions limit eligibility to grid-connected, domestic renewables. The RPS is usually applied to producers rather than consumers, and to energy output not capacity. Flexibility mechanisms are desired but a challenge to implement. Administration in the US an Australia is by government with delegation to independent utility regulators, while in Europe it is more the responsibility of government. Everywhere, the RPS is applied alongside other mechanisms of renewables support.
02/02103 Whole tires/mixed-feedstock gasification for syngas production Phillips, B. D. Proceedings - Annual International Pittsburgh Coal Conference, 2000, (17), 150-156. Emery Recycling Corporatio n (ERC) developed a fixed-bed, slagging gasification technology capable of converting whole scrap tires into a syngas. ERC has 1 pilot-plant built in Utah, USA where all testing and operations were made. For a period of 90 operating days within a 20mo staffed period, ERC operated the gasifier and converted solid fuels (primarily scrap tires and some wood waste) to gas at efficiencies of 92% at relatively low throughout (5-16 tons/day), while not producing tars or oils. Due to the pilot-plant limited throughput and with currently no local end-use for the gaseous fuel (with the exception of the possibility of power generation to the grid), E R C does not operate the pilot-plant at this time. ERC conducted extensive market research on scrap tire availability and prepared financial models and pro-formas that show profitable plant operations. Individual plant economics for commercial facilities depend on availability (volume and price) of feedstock and valuation of the gaseous fuel to specific industries. ERC also prepared detailed financial models that can input specific plant configurations including feedstock mix ratios and market conditions to determine plant costs and return on investment. ERC is seeking capital monies to further develop the technology by building a new gasifier with higher throughput capacities that will specifically process coal and whole scrap tires. Products obtained from this 1st demo/com, plant will be a syngas high in H and CO that will provide process heat for industry. ERC plans to incorporate the use of O and steam to increase process control and decrease facility size while increasing product output flexibility, including the production of medium and high Btu gases and possible liquid derivatives such as MeOH. On completion of successful demonstration, ERC wishes to deploy the technology to other suitable locations in the US and foreign markets.
272
Fuel and Energy Abstracts July 2002
08
STEAM RAISING Boiler operation/design
02/02104 An investigation of carbon loss in CFB boilers burning hard coals Li, Y. et al. Proceedings of the International Conference on Fluidized Bed Combustion, 2001, (16), 108-113. The reported carbon loss for CFB boilers, most of which are burning reactive fuels, such as lignite, peat etc., is typically very low. However, most Chinese CFB boilers must burn hard coals, such as anthracite, bituminous and coal wastes etc., and for these CFBC boilers, the carbon content in fly ash was higher than expected. The present paper provides information carbon loss in Chinese CFB boilers burning hard coals. A series of field-tests and laboratory investigations were carried out to determine the mechanisms for carbon burnout in CFB. The behaviour of char during combustion such as fragmentation, attrition, etc., are strongly related to the parent coal, and powerfully influence the carbon burn out in a CFB boiler. The present research also provides information on the char deactivation that occurs during char burnout in fluidized bed combustion, especially for large particles from low rank coal. Also, uneven mixing of solids and gas in the core region of the furnace play a central role in causing poor burnout of carbon in CFB fly ashes. Several suggestions are made for the CFB boiler design to improve the carbon loss of the boiler.
02/02105 Application of membrane technology for oxygen enrichment in coal-fired boiler Fang, S. Mo Kexue Yu Jishu, 2001, 21, (3), 46-49. (In Chinese) The technology and installation of membrane oxygen-enriched air used in the coal-fired boiler for the first time is introduced in this paper. The technological process, equipment, the condition of installation and trial run are described as well. The energy-saving result and economic benefit are also discussed.
02/02106 Babcock & Wilcox CFB boilers - design and experience Belin, E. et al. Proceedings of the International Conference on Fluidized Bed Combustion, 2001, (16), 784-792. The distinctive feature of Babcock & Wilcox (B&W) CFB boilers is a two-stage solids separation system consisting of the impact-type primary solids separator (U-beams) and the secondary multi-cyclone dust collector. Lessons learned from 15 years of B&W's CFB technological application have been used to develop a reliable, low cost boiler design. Advantages of boilers with a two-stage solids separation system are described. Operation of B&W coal-fired CFB boilers over the last 10 years has demonstrated high reliability of the two-stage solids separator. Superior solids collection efficiency of the two-stage separator provides higher furnace heat-transfer rate, ability to better control furnace temperature, and increased residence time of fine carbon and sorbent particles. As a result, the required boiler performance is achieved with lower furnace height and smaller boiler footprint. The current B&W IR-CFB boiler design is described. Compactness of the IR-CFB makes it especially attractive for PC boiler retrofit applications. Considerations for IR-CFB scale-up are provided.
02/02107 Co-firing of coal and feedlot biomass (FB) in a laboratory scale boiler burner Annamalai, K. et al. Proceedings - Annual International Pittsburgh Coal Conference, 2000, (17), 1200-1221. The use of biomass as a fuel source has the potential to both solve biomass disposal problems, and reduce emissions. Previous attempts to utilize biomass as a sole fuel source met with only limited success due to the higher ash and moisture of biomass and inconsistent properties. Thus, cofiring technology is proposed where cattle manure (henceforth called feedlot biomass, FB) is ground, mixed with coal, and then fired in existing pulverized coal fired boiler burner facilities. The coal having higher BTU content enables the low quality FB to burn. Thermogravimetric analyses (TGA) were performed on coal, FB, and 90:10 coal: FB blend. The TGA studies found that biomass will release volatiles at a lower temperature, about 100 K lower than that of coal, and more rapidly than coal. While the single parallel reaction model seems to fit the pyrolysis of coal, a bimodal parallel reaction model appears to fit the pyrolysis curve of biomass. Coal and coal: FB blends were first fired in a stainless steel eombustor unit and by using gas analyses, transient combustion and pollutant emission characteristics were obtained. Subsequently, the combustor unit was modified with a cast ceramic liner and a combustion feeding system for firing coal and then blends. The boiler burner experiments revealed that the 90:10-blend burns
02/02102 The renewable portfolio standard: design considerations and an implementation survey Berry, T. and Jaccard, M. Energy Policy, 2001, 29, (4), 263-277. Renewables have social and environmental benefits compared to conventional electricity sources, but are rarely competitive on a strict financial cost basis. This is because conventional sources are sometimes subsidized, their full pollution costs are ignored, and renewables involve newer, higher-cost technologies whose relative costs will fall with commercialization. Governments use several mechanisms to support renewables, including direct financial support (grants, loans), indirect support (R&D, demonstrations), reform of financial costs of conventional sources (subsidy removal, pollution taxes), and the Renewable Portfolio Standard (RPS). The RPS requires a minimum share of electricity from renewable energy sources. Its use is spreading because it maintains an incentive for renewable producers to reduce cost, links the regulated market outcome to an environmental target, and reduces government involvement. Although it is too early to evaluate fully its effectiveness, the survey for this study explored implementation issues in three European countries, nine US states, and Australia, and found the following. The RPS target is usually set to have environmental benefits without causing significant price increases (cost caps are sometimes used). Most jurisdictions limit eligibility to grid-connected, domestic renewables. The RPS is usually applied to producers rather than consumers, and to energy output not capacity. Flexibility mechanisms are desired but a challenge to implement. Administration in the US an Australia is by government with delegation to independent utility regulators, while in Europe it is more the responsibility of government. Everywhere, the RPS is applied alongside other mechanisms of renewables support.
02/02103 Whole tires/mixed-feedstock gasification for syngas production Phillips, B. D. Proceedings - Annual International Pittsburgh Coal Conference, 2000, (17), 150-156. Emery Recycling Corporatio n (ERC) developed a fixed-bed, slagging gasification technology capable of converting whole scrap tires into a syngas. ERC has 1 pilot-plant built in Utah, USA where all testing and operations were made. For a period of 90 operating days within a 20mo staffed period, ERC operated the gasifier and converted solid fuels (primarily scrap tires and some wood waste) to gas at efficiencies of 92% at relatively low throughout (5-16 tons/day), while not producing tars or oils. Due to the pilot-plant limited throughput and with currently no local end-use for the gaseous fuel (with the exception of the possibility of power generation to the grid), E R C does not operate the pilot-plant at this time. ERC conducted extensive market research on scrap tire availability and prepared financial models and pro-formas that show profitable plant operations. Individual plant economics for commercial facilities depend on availability (volume and price) of feedstock and valuation of the gaseous fuel to specific industries. ERC also prepared detailed financial models that can input specific plant configurations including feedstock mix ratios and market conditions to determine plant costs and return on investment. ERC is seeking capital monies to further develop the technology by building a new gasifier with higher throughput capacities that will specifically process coal and whole scrap tires. Products obtained from this 1st demo/com, plant will be a syngas high in H and CO that will provide process heat for industry. ERC plans to incorporate the use of O and steam to increase process control and decrease facility size while increasing product output flexibility, including the production of medium and high Btu gases and possible liquid derivatives such as MeOH. On completion of successful demonstration, ERC wishes to deploy the technology to other suitable locations in the US and foreign markets.
272
Fuel and Energy Abstracts July 2002
08
STEAM RAISING Boiler operation/design
02/02104 An investigation of carbon loss in CFB boilers burning hard coals Li, Y. et al. Proceedings of the International Conference on Fluidized Bed Combustion, 2001, (16), 108-113. The reported carbon loss for CFB boilers, most of which are burning reactive fuels, such as lignite, peat etc., is typically very low. However, most Chinese CFB boilers must burn hard coals, such as anthracite, bituminous and coal wastes etc., and for these CFBC boilers, the carbon content in fly ash was higher than expected. The present paper provides information carbon loss in Chinese CFB boilers burning hard coals. A series of field-tests and laboratory investigations were carried out to determine the mechanisms for carbon burnout in CFB. The behaviour of char during combustion such as fragmentation, attrition, etc., are strongly related to the parent coal, and powerfully influence the carbon burn out in a CFB boiler. The present research also provides information on the char deactivation that occurs during char burnout in fluidized bed combustion, especially for large particles from low rank coal. Also, uneven mixing of solids and gas in the core region of the furnace play a central role in causing poor burnout of carbon in CFB fly ashes. Several suggestions are made for the CFB boiler design to improve the carbon loss of the boiler.
02/02105 Application of membrane technology for oxygen enrichment in coal-fired boiler Fang, S. Mo Kexue Yu Jishu, 2001, 21, (3), 46-49. (In Chinese) The technology and installation of membrane oxygen-enriched air used in the coal-fired boiler for the first time is introduced in this paper. The technological process, equipment, the condition of installation and trial run are described as well. The energy-saving result and economic benefit are also discussed.
02/02106 Babcock & Wilcox CFB boilers - design and experience Belin, E. et al. Proceedings of the International Conference on Fluidized Bed Combustion, 2001, (16), 784-792. The distinctive feature of Babcock & Wilcox (B&W) CFB boilers is a two-stage solids separation system consisting of the impact-type primary solids separator (U-beams) and the secondary multi-cyclone dust collector. Lessons learned from 15 years of B&W's CFB technological application have been used to develop a reliable, low cost boiler design. Advantages of boilers with a two-stage solids separation system are described. Operation of B&W coal-fired CFB boilers over the last 10 years has demonstrated high reliability of the two-stage solids separator. Superior solids collection efficiency of the two-stage separator provides higher furnace heat-transfer rate, ability to better control furnace temperature, and increased residence time of fine carbon and sorbent particles. As a result, the required boiler performance is achieved with lower furnace height and smaller boiler footprint. The current B&W IR-CFB boiler design is described. Compactness of the IR-CFB makes it especially attractive for PC boiler retrofit applications. Considerations for IR-CFB scale-up are provided.
02/02107 Co-firing of coal and feedlot biomass (FB) in a laboratory scale boiler burner Annamalai, K. et al. Proceedings - Annual International Pittsburgh Coal Conference, 2000, (17), 1200-1221. The use of biomass as a fuel source has the potential to both solve biomass disposal problems, and reduce emissions. Previous attempts to utilize biomass as a sole fuel source met with only limited success due to the higher ash and moisture of biomass and inconsistent properties. Thus, cofiring technology is proposed where cattle manure (henceforth called feedlot biomass, FB) is ground, mixed with coal, and then fired in existing pulverized coal fired boiler burner facilities. The coal having higher BTU content enables the low quality FB to burn. Thermogravimetric analyses (TGA) were performed on coal, FB, and 90:10 coal: FB blend. The TGA studies found that biomass will release volatiles at a lower temperature, about 100 K lower than that of coal, and more rapidly than coal. While the single parallel reaction model seems to fit the pyrolysis of coal, a bimodal parallel reaction model appears to fit the pyrolysis curve of biomass. Coal and coal: FB blends were first fired in a stainless steel eombustor unit and by using gas analyses, transient combustion and pollutant emission characteristics were obtained. Subsequently, the combustor unit was modified with a cast ceramic liner and a combustion feeding system for firing coal and then blends. The boiler burner experiments revealed that the 90:10-blend burns