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Modeling fluidized bed combustion of high-volatile solid fuels
11 Process heating, power and incineration (energy applications in industry) introduces the design features of the 12 MW multi-generation system in detail. A simplified model developed for the multi-generation system is used to predict the performance parameters.
03/00755 Development of RTP for industrial solar cell processing Horzel, J. et al. Solar Energy Materials and Solar Cells, 2002, 72, (1 4), 263-269. Rapid thermal processing (RTP), originally developed for processing microelectronic devices has been investigated in the recent decade for its potential in the production of Si solar cells. This paper will discuss the use of RTP for industrial Si solar cells with screen-printed contacts. Printed metal contacts require adapted emitters when good fill factors should be achieved. Multi-crystalline Si substrates are required to adapt the temperature ramps of RTP to avoid minority carrier lifetime degradation from activated defect centres. Finally, industrial processing requires high throughput that cannot be achieved with conventional RTP equipment. This paper will present an advanced selective emitter process and a recently developed continuous RTP system that meets for the first time the requirements to make RTP compatible with industrial solar cell processing. The limits of industrial RTP solar cell processing will be discussed.
03/00756 Dynamic mathematical model of pressurized fluidized bed combustor Li, Z. et al. Huagong Xuebao, 2002, 53, (4), 349-354. (In Chinese) The dynamic model of a pressurized fluidized bed combustor was studied. In order to reflect the distribution of temperature along the axial direction as well as to increase the speed of model calculation, a combined discretization strategy was applied, which divided the combustor into a certain number of cells for hydrodynamic and heat transfer calculations and further grouped some neighbouring cells into a smaller number of sections for mass and energy balance calculations. By dividing the dense bed into three different phase and considering the bubble behaviour and gas mass transfer between the adjacent phases, the model was able to simulate the bypassing of oxygen from bottom to the freeboard as well as the difference of oxygen concentration in different phases. The dynamic model was set up based on the dynamic balance equations of solid mass, oxygen mass, carbon mass and total energy in each section. The static balance calculation results of the model were compared with the experimental data from a real 60th 1 PFBC boiler and agreement was found to some extent. Finally, the fast bottom ash draining process was simulated with the model, which showed that the model indeed had the ability to describe this unique load changing operation of PFBC correctly and reflected the combustion mechanism of fluidized bed essentially.
03/00757 Efficient operation of blast furnaces under low fuel consumption Orimoto, T. and Koizumi, F. Jpn. Kokai Tokkyo Koho JP 2002 146,414 (CI. C21B5/00), 22 May 2002, Appl. 2000/337,367, 6 Nov 2000. 4. (In Japanese) On operation of blast furnace by using Fe raw materials containing > 1.8 weight% A1203 with blowing of _>150 kg/ton pulverized carbon from tuyere, the amount of H charged into the furnace is limited to 610 kg/ton. Blast furnace operation is carried out under high efficiency even under use of low-cost high-AlzO3 ores.
03/00758 devices
Fuel composition for cement manufacturing
Takemoto, T. and Ochi, Y. Jpn. Kokai Tokkyo Koho JP 2002 180,073 (CI. C10L5/48), 26 Jun 2002,.Appl. 2000/379,287, 13 Dec 2000. 6. (In Japanese) The fuel composition comprises 100 weight parts crushed fibrereinforced plastics having an average length < 10 mm and 1-200 weight parts a combustible liquid having a vapour pressure of <2.3 kPa and viscosity of <5000 mPa s at 20 °. The fuel composition is easily fed to the cement manufacturing devices without dusting.
03/00759 Hydrogen fuel from synthesis gas production used for electric power generation Holling, B. Get. Offen. De 10.057,960 (CI. H0IM8/00), 29 May 2002, Appi. 10,057960, 22 Nov 2000. 4. (In German) This paper looks at a procedure for the generation of electricity from H2, produced as waste product by the CO synthesis gas production. The thermal energy of Ha is released, and converted in electric energy by using a fuel cell element.
03/00760 Magnetically stabilized fluidized beds for fine coal separation Fan, M. et al. Powder Technology, 2002, 123, (2-3), 208-211.
Based on a prior study on air-fluidized dense media for 6-50-ram coal preparation, this paper presents results on magnetically stabilized fluidized beds (MSFB) on fine 1-6-mm coal preparation. Magnetic stabilization improves separation by lowering the lower size limit of separation and by preventing back mixing of the separated solids. This work addresses the fluidization media characteristics, the experimental system and separation results.
03/00761 plants
Materials for ultra supercritical coal-fired power
Viswanathan, R. et al. Proceedings of the International Technical Conference on Coal Utilization & Fuel Systems, 2002, 1, (27), 257-272. The US Department of Energy and the Ohio Coal Development Office have recently initiated a project aimed at identifying, evaluating, and qualifying the materials needed for the construction of the critical components of coal-fired power plants capable of operating at 50-55% efficiency (based on the higher heating value of the fuel). This increased efficiency compared to current coal-fired power plants is achieved principally through the use of ultra-supercritical steam conditions (USC), which implies operation at higher steam temperatures and pressures. The project goal is to increase the operating temperature to 760 ° t.1400°F), while attention also is given to identifying the materials issues involved in service at temperatures up to 870 ° (1600°F). The programme is intended to complement alloy development programmes now being carried out in Japan and Europe. Those programmes have identified ferritic steels capable of meeting the strength requirements of USC plants to approx. 620 °, but it is not clear if such alloys would be capable of further development. In this programme, the maximum temperature capabilities of these and other available high-temperature alloys are being assessed to provide a basis for materials selection and application, and to allow confidence in their use. The programme approach makes use of developments in understanding and modelling of alloy structure-property relationships to guide the mechanical property measurements needed to evaluate the fabrication issues and long-term microstructural stability issues of concern and is also addressing concerns about long-term durability in both the anticipated fireside and steam-side environments. Feedback from these various analyses is being used as input to considerations of the viability of alternative paths to alloy modification or new alloy development, should these be needed.
03/00762 Method of operating a furnace Hilton, M. and Kippax, J. W. PCT Int. Appl. WO 02 40,396 (CI. C01B3/ 38), 23 May 2002, GB Appl. 2000/28,108, 17 Nov 2000. 26. This method uses a H-rich gas as furnace fuel and many burners to burn the fuel. A means to ignite a flame for at least one of the burners is provided. An O-containing gas and a combustion hydrocarbon gas are supplied to each of the burners as an ignitable mixture. A flame is ignited at a predetected burner which is then allowed to propagate to the other burners. The composition of the feed gas is then altered over a period of time to replace a major part of the hydrocarbon gas by a Hrich gas until a H flame is established at each of the burners.
03/00763 Modeling fluidized bed combustion of highvolatile solid fuels Scala, F. and Salatino, P. Chemical Engineering Science, 2002, 57, (7), 1175-1 t96. A model of an atmospheric bubbling fluidized bed combustor operated with high-volatile solid fuel feedings is presented. It aims at the assessment of axial burning profiles along the reactor and of the associated temperature profiles, relevant to combustor performance and operability. The combustor is divided into three sections: the dense bed, the splashing region and the freeboard. Three combustible phases are considered: volatile matter, relatively large non-elutriable char particles and fine char particles of elutriable size. The model takes into account phenomena that assume particular importance with highvolatile solid fuels, namely fuel particle fragmentation and attrition in the bed and volatile matter segregation and post-combustion above the bed. An energy balance on the splashing zone is set up, taking into account volatile matter elutriated fines post-combustion and radiative and convective heat fluxes to the bed and the freeboard. Results from calculations with a high-volatile biomass fuel indicate that combustion occurs to comparable extents in the bed and in the splashing region of the combustor. Due to volatile matter segregation with respect to the bed, a significant fraction of the heat is released into the splashing region of the combustor and this results in an increase of the temperature in this region. Extensive bed solids recirculation associated to solids ejection/falling back due to bubbles bursting at bed surface promotes thermal feedback from this region to the bed of as much as 80-90% of the heat released by afterburning of volatile matter and elutriated fines. Depending on the operating conditions a significant fraction of the volatile matter may burn in the freeboard or in the cyclone.
Fuel and Energy Abstracts
March 2003
101
03/00755 Development of RTP for industrial solar cell processing Horzel, J. et al. Solar Energy Materials and Solar Cells, 2002, 72, (1 4), 263-269. Rapid thermal processing (RTP), originally developed for processing microelectronic devices has been investigated in the recent decade for its potential in the production of Si solar cells. This paper will discuss the use of RTP for industrial Si solar cells with screen-printed contacts. Printed metal contacts require adapted emitters when good fill factors should be achieved. Multi-crystalline Si substrates are required to adapt the temperature ramps of RTP to avoid minority carrier lifetime degradation from activated defect centres. Finally, industrial processing requires high throughput that cannot be achieved with conventional RTP equipment. This paper will present an advanced selective emitter process and a recently developed continuous RTP system that meets for the first time the requirements to make RTP compatible with industrial solar cell processing. The limits of industrial RTP solar cell processing will be discussed.
03/00756 Dynamic mathematical model of pressurized fluidized bed combustor Li, Z. et al. Huagong Xuebao, 2002, 53, (4), 349-354. (In Chinese) The dynamic model of a pressurized fluidized bed combustor was studied. In order to reflect the distribution of temperature along the axial direction as well as to increase the speed of model calculation, a combined discretization strategy was applied, which divided the combustor into a certain number of cells for hydrodynamic and heat transfer calculations and further grouped some neighbouring cells into a smaller number of sections for mass and energy balance calculations. By dividing the dense bed into three different phase and considering the bubble behaviour and gas mass transfer between the adjacent phases, the model was able to simulate the bypassing of oxygen from bottom to the freeboard as well as the difference of oxygen concentration in different phases. The dynamic model was set up based on the dynamic balance equations of solid mass, oxygen mass, carbon mass and total energy in each section. The static balance calculation results of the model were compared with the experimental data from a real 60th 1 PFBC boiler and agreement was found to some extent. Finally, the fast bottom ash draining process was simulated with the model, which showed that the model indeed had the ability to describe this unique load changing operation of PFBC correctly and reflected the combustion mechanism of fluidized bed essentially.
03/00757 Efficient operation of blast furnaces under low fuel consumption Orimoto, T. and Koizumi, F. Jpn. Kokai Tokkyo Koho JP 2002 146,414 (CI. C21B5/00), 22 May 2002, Appl. 2000/337,367, 6 Nov 2000. 4. (In Japanese) On operation of blast furnace by using Fe raw materials containing > 1.8 weight% A1203 with blowing of _>150 kg/ton pulverized carbon from tuyere, the amount of H charged into the furnace is limited to 610 kg/ton. Blast furnace operation is carried out under high efficiency even under use of low-cost high-AlzO3 ores.
03/00758 devices
Fuel composition for cement manufacturing
Takemoto, T. and Ochi, Y. Jpn. Kokai Tokkyo Koho JP 2002 180,073 (CI. C10L5/48), 26 Jun 2002,.Appl. 2000/379,287, 13 Dec 2000. 6. (In Japanese) The fuel composition comprises 100 weight parts crushed fibrereinforced plastics having an average length < 10 mm and 1-200 weight parts a combustible liquid having a vapour pressure of <2.3 kPa and viscosity of <5000 mPa s at 20 °. The fuel composition is easily fed to the cement manufacturing devices without dusting.
03/00759 Hydrogen fuel from synthesis gas production used for electric power generation Holling, B. Get. Offen. De 10.057,960 (CI. H0IM8/00), 29 May 2002, Appi. 10,057960, 22 Nov 2000. 4. (In German) This paper looks at a procedure for the generation of electricity from H2, produced as waste product by the CO synthesis gas production. The thermal energy of Ha is released, and converted in electric energy by using a fuel cell element.
03/00760 Magnetically stabilized fluidized beds for fine coal separation Fan, M. et al. Powder Technology, 2002, 123, (2-3), 208-211.
Based on a prior study on air-fluidized dense media for 6-50-ram coal preparation, this paper presents results on magnetically stabilized fluidized beds (MSFB) on fine 1-6-mm coal preparation. Magnetic stabilization improves separation by lowering the lower size limit of separation and by preventing back mixing of the separated solids. This work addresses the fluidization media characteristics, the experimental system and separation results.
03/00761 plants
Materials for ultra supercritical coal-fired power
Viswanathan, R. et al. Proceedings of the International Technical Conference on Coal Utilization & Fuel Systems, 2002, 1, (27), 257-272. The US Department of Energy and the Ohio Coal Development Office have recently initiated a project aimed at identifying, evaluating, and qualifying the materials needed for the construction of the critical components of coal-fired power plants capable of operating at 50-55% efficiency (based on the higher heating value of the fuel). This increased efficiency compared to current coal-fired power plants is achieved principally through the use of ultra-supercritical steam conditions (USC), which implies operation at higher steam temperatures and pressures. The project goal is to increase the operating temperature to 760 ° t.1400°F), while attention also is given to identifying the materials issues involved in service at temperatures up to 870 ° (1600°F). The programme is intended to complement alloy development programmes now being carried out in Japan and Europe. Those programmes have identified ferritic steels capable of meeting the strength requirements of USC plants to approx. 620 °, but it is not clear if such alloys would be capable of further development. In this programme, the maximum temperature capabilities of these and other available high-temperature alloys are being assessed to provide a basis for materials selection and application, and to allow confidence in their use. The programme approach makes use of developments in understanding and modelling of alloy structure-property relationships to guide the mechanical property measurements needed to evaluate the fabrication issues and long-term microstructural stability issues of concern and is also addressing concerns about long-term durability in both the anticipated fireside and steam-side environments. Feedback from these various analyses is being used as input to considerations of the viability of alternative paths to alloy modification or new alloy development, should these be needed.
03/00762 Method of operating a furnace Hilton, M. and Kippax, J. W. PCT Int. Appl. WO 02 40,396 (CI. C01B3/ 38), 23 May 2002, GB Appl. 2000/28,108, 17 Nov 2000. 26. This method uses a H-rich gas as furnace fuel and many burners to burn the fuel. A means to ignite a flame for at least one of the burners is provided. An O-containing gas and a combustion hydrocarbon gas are supplied to each of the burners as an ignitable mixture. A flame is ignited at a predetected burner which is then allowed to propagate to the other burners. The composition of the feed gas is then altered over a period of time to replace a major part of the hydrocarbon gas by a Hrich gas until a H flame is established at each of the burners.
03/00763 Modeling fluidized bed combustion of highvolatile solid fuels Scala, F. and Salatino, P. Chemical Engineering Science, 2002, 57, (7), 1175-1 t96. A model of an atmospheric bubbling fluidized bed combustor operated with high-volatile solid fuel feedings is presented. It aims at the assessment of axial burning profiles along the reactor and of the associated temperature profiles, relevant to combustor performance and operability. The combustor is divided into three sections: the dense bed, the splashing region and the freeboard. Three combustible phases are considered: volatile matter, relatively large non-elutriable char particles and fine char particles of elutriable size. The model takes into account phenomena that assume particular importance with highvolatile solid fuels, namely fuel particle fragmentation and attrition in the bed and volatile matter segregation and post-combustion above the bed. An energy balance on the splashing zone is set up, taking into account volatile matter elutriated fines post-combustion and radiative and convective heat fluxes to the bed and the freeboard. Results from calculations with a high-volatile biomass fuel indicate that combustion occurs to comparable extents in the bed and in the splashing region of the combustor. Due to volatile matter segregation with respect to the bed, a significant fraction of the heat is released into the splashing region of the combustor and this results in an increase of the temperature in this region. Extensive bed solids recirculation associated to solids ejection/falling back due to bubbles bursting at bed surface promotes thermal feedback from this region to the bed of as much as 80-90% of the heat released by afterburning of volatile matter and elutriated fines. Depending on the operating conditions a significant fraction of the volatile matter may burn in the freeboard or in the cyclone.
Fuel and Energy Abstracts
March 2003
101