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02031 Release of alkali salts and coal volatiles affecting internal components in fluidized bed combustion systems
11 Process heating, power and incineration (energy applications in industry) A pneumatically conveyed flow of solids is continuously introduced into a pressure vessel in which a fluidized bed is maintained by adding a fluidization gas. The fluidized bed is heated by heat exchange with a heat-transfer medium. The solid-gas mixture is continuously withdrawn from the fluidized bed and divided into a lean gas phase and a highly compressed solid-gas mixture by gravitational or centrifugal separation. The highly compressed solid-gas mixture is then continuously discharged into a pneumatic transport line and conveyed pneumatically. The solid content of the pressure vessel is continuously monitored. The continuous discharge of the highly compressed solid/ gas mixture into the pneumatic transport line is controlled via a controlled gas withdrawal from the lean gas phase in such a manner that the solid content of the pressure vessel remains substantially constant.
calculations were carried out for conventional and bathtub gas inlet chambers. Results show that in the bathtub cooler the mean residence time of the gas and coke particle can be reduced to > 50% of the residence time of the gas and coke particles in the conventional TLE. Protective grids, which main purpose is to protect the oval-header tubesheet from erosion have also positive effect on the gas flow distribution into the individual tubes. Pressure and gas velocity profiles shown on the diagrams demonstrate the advantages and specific differences between both types of coolers. Results from theory calculations are confirmed in actual operation on both type of coolers.
04/02028 NxO emission from industrial fluidized-bed combustion chambers
Dhingra, S. et al. Biomass and Bioenergy, 2004, 26, (2), 195-203. The Energy and Resources Institute (TERI) has been actively involved in the development of biomass gasifler system for thermal and power generation use. Though the basic science of gasification is well established, there have not many efforts in the past on product development. By continuous interaction with users, silk experts and consultants, TERI could able to develop a gasifier based silk reeling oven. A major thrust on this development work was to evolve marketable product by continued efforts to gain an insight of the actual process and user feedback through an extended presence and interaction at field level, and then translating this experience in product design. The present paper gives a summary of design, development and testing of gasifier based cottage basin system for cocoon cooking in silk reeling industry in order to achieve higher fuel efficiency and increase productivity of the process. The paper describes in detail the approach of different technology development stages, its testing both at laboratory and field and economic viability of the system.
Tomeczek, J. et al. Gospodarka Paliwami i Energia, 2003, 51, (3), 5-8. (In Polish) Contrary to NOx emission, N20 emission from circulating fluidized bed combustion of coal decreases with increasing temperature. At 800-850 ° the emission of NzO from the combustion of Upper Silesian coal is in the range of 110-140 mg/MJ. Dosing a reducing gas to flue gases exiting the cyclone is a technically proven way to decrease N2O emission from fluidized bed combustion chambers.
04/02029 On the fouling mechanism of non-bounded oil shale ash deposits on boiler heat-transfer surfaces Ots, A. and Tiikma, T. Oil Shale, 2003, 20, (l), 3-13. As shown by preliminary pilot-scale experiments on oil shale combustion in circulating fluidized bed, deposition of very fine particles in the convective part of boiler takes place. Assuming a quite complete binding of sulfur in circulating fluidized bed combustor and taking into account low-temperature level of this combustion process, there will not be adequate conditions for formation of bounded deposits on convective boiler surfaces and the fouling process will be controlled mainly by thermophoretic, diffusion and adhesion forces. That might invoke a forced increase in deposits with high thermal resistance. The prognosis of that process is presented in the paper.
04/02030 Oxygen blast furnace and combined cycle (OBFCC). An efficient iron-making and power generation process Jianwei, Y. et al. Energy, 2003, 28, (8), 825-835. A new iron and power generating process, oxygen blast furnace and combined cycle (OBF-CC), is presented. The features of the oxygen blast furnace and integrated coal gasification and combined cycle (IGCC) are summarized. The relation between the blasting parameters and the output gas quantity, as well as caloric value is calculated based on mass and energy balance. The OBF-CC will be an efficient ironmaking and power generation process with higher energy efficiency and less pollution.
04/02033 Technology intervention to improve the energy efficiency and productivity of silk reeling sector
04/02034 Texturing industrial multicrystalline silicon solar cells Macdonald, D. H. et al, Solar Energy, 2004, 76, (1-3), 277-283. Three potential techniques for texturing commercial multicrystalline silicon solar cells are compared on the basis of reflectance measurements. Wet acidic texturing, which would be the least costly to implement, produces a modest improvement in reflection before antireflection coating and encapsulation, whereas maskless reactiveion etching texturing, and especially masked reactive-ion etched 'pyramids', generate a larger gain in absorption. After antireflection coating and encapsulation however, the differences between the methods are reduced. Short-circuit current measurements on wet acidic textured cells reveal that there is a significant additional current gain above that expected from the reduced reflection. This is attributed to both light-trapping and oblique coupling of incident light into the cell, resulting in generation closer to the junction.
04/02031 Release of alkali salts and coal volatiles affecting internal components in fluidized bed combustion systems del Campo, E. A.. et al. Revista de Metalurgia, 2003, 15-22. In spite of the potential advantages of atmospheric fluidized bed systems, experience has proved that, under certain environments and operating conditions, a given material employed for internal components could lead to catastrophic events. In this study, an attempt is made to establish material selection and operational criteria that optimize performance and availability based on theory considerations of the bed hydrodynamics, thermodynamic and combustion process. The theory results may indicate that, for high-volatile coals with particle diameters (de) of 1-3 m m and sand particle size (d~) of 0.674 ram, a considerable proportion of alkali chlorides may be transferred into the freeboard region of fluidized bed combustors as vapour phase, at bed temperatures (Tb) < 840°C, excess air (XSA) < 20%, static bed height (Hg) < 0.2 m and fluidizing velocity (Uo) < 1 m/s. Under these operating conditions, a high alkali deposition may be expected to occur in heat exchange tubes located above the bed. Conversely, when the combustors operate at Tb > 890°C and XSA > 30%, a high oxidation rate of the in-bed tubes may be present. Nevertheless, for these higher Tb value sand XSA < 10%, corrosion attack of metallic components, via sulfidation, would occur since the excessive gas-phase combustion within the bed induced a local oxygen depletion.
04/02032 Simulation of the gas flow distribution in the inlet chamber of the conventional and bathtub TLE Jekerle, J. American Institute of Chemical Engineers, 2003, 1394~1420. The bathtub transfer line exchanger differs from the conventional transfer line exchanger (TLE) in the arrangement of the tubes and the shape of the gas inlet chamber. Multiple gas inlet nozzles, reduced volume and an optimized internal shape of the gas inlet chamber have a favourable effect on the gas velocity profile, residence time of gas and deposits of coke. Numerous computational f u i d dynamic (CFD)
280 Fuel and Energy Abstracts July 2004
04/02035 The fiber optic system detecting the type of burned fuel in power boilers Wojcik, W. et al. Proceedings of SPIE - The International Society for Optical Engineering, 2003, 5028, (8), 131-135. The study presents the method of detecting the type of burned fuel in industrial conditions. Wavelet transforms were applied for th e signals corresponding to pulsation of chosen flame zone.
04/02036 Trace elements in circulating fluidized bed combustion of coal Zhang, J. et al. Ranshao Kexue Yu Jishu, 2003, 9, (1), 64-67. (In Chinese) For the better understanding of the partitioning behaviours of trace elements and their emissions with or without additive during circulating fluidized bed (CFB) combustion of coal, the coal was burned in a small CFB combustor. Coal samples, including CFB ash, magnetic ash in CFB ash, ash from chimney after dust remover and spraying water from chimney, were collected and analysed using ICP-AES, AFS, INAA, ICS and CV-AAS. The experimental result shows that the trace elements (As, Sb, Pb, Cu, Be, Zn) are enriched substantially in the fine particles of CFB ash, and Pb, As, Sb, Se, Th, Ni, Cr are enriched in the magnetic ash in CFB ash. In the ash from the chimney after dust removal, Zn, As, P, Ni, Cr, Mo, Be, Pb, Th, Hg, F are enriched while Nb, Rb, Zr are obviously deficient. With sulfur capture additive, the contents of As, Se, Sb, Zn in the fine particles of CFB ash decrease, and the contents of As, Se, Li, Be, Mo, Cr, Co, Ni in the ash from chimney after dust remover and the contents of Cu, Zn, Cr, Pb, Co, Ni, F, and Se in the spraying water from chimney decrease. Additives can control the emission of some potentially hazardous trace elements.
calculations were carried out for conventional and bathtub gas inlet chambers. Results show that in the bathtub cooler the mean residence time of the gas and coke particle can be reduced to > 50% of the residence time of the gas and coke particles in the conventional TLE. Protective grids, which main purpose is to protect the oval-header tubesheet from erosion have also positive effect on the gas flow distribution into the individual tubes. Pressure and gas velocity profiles shown on the diagrams demonstrate the advantages and specific differences between both types of coolers. Results from theory calculations are confirmed in actual operation on both type of coolers.
04/02028 NxO emission from industrial fluidized-bed combustion chambers
Dhingra, S. et al. Biomass and Bioenergy, 2004, 26, (2), 195-203. The Energy and Resources Institute (TERI) has been actively involved in the development of biomass gasifler system for thermal and power generation use. Though the basic science of gasification is well established, there have not many efforts in the past on product development. By continuous interaction with users, silk experts and consultants, TERI could able to develop a gasifier based silk reeling oven. A major thrust on this development work was to evolve marketable product by continued efforts to gain an insight of the actual process and user feedback through an extended presence and interaction at field level, and then translating this experience in product design. The present paper gives a summary of design, development and testing of gasifier based cottage basin system for cocoon cooking in silk reeling industry in order to achieve higher fuel efficiency and increase productivity of the process. The paper describes in detail the approach of different technology development stages, its testing both at laboratory and field and economic viability of the system.
Tomeczek, J. et al. Gospodarka Paliwami i Energia, 2003, 51, (3), 5-8. (In Polish) Contrary to NOx emission, N20 emission from circulating fluidized bed combustion of coal decreases with increasing temperature. At 800-850 ° the emission of NzO from the combustion of Upper Silesian coal is in the range of 110-140 mg/MJ. Dosing a reducing gas to flue gases exiting the cyclone is a technically proven way to decrease N2O emission from fluidized bed combustion chambers.
04/02029 On the fouling mechanism of non-bounded oil shale ash deposits on boiler heat-transfer surfaces Ots, A. and Tiikma, T. Oil Shale, 2003, 20, (l), 3-13. As shown by preliminary pilot-scale experiments on oil shale combustion in circulating fluidized bed, deposition of very fine particles in the convective part of boiler takes place. Assuming a quite complete binding of sulfur in circulating fluidized bed combustor and taking into account low-temperature level of this combustion process, there will not be adequate conditions for formation of bounded deposits on convective boiler surfaces and the fouling process will be controlled mainly by thermophoretic, diffusion and adhesion forces. That might invoke a forced increase in deposits with high thermal resistance. The prognosis of that process is presented in the paper.
04/02030 Oxygen blast furnace and combined cycle (OBFCC). An efficient iron-making and power generation process Jianwei, Y. et al. Energy, 2003, 28, (8), 825-835. A new iron and power generating process, oxygen blast furnace and combined cycle (OBF-CC), is presented. The features of the oxygen blast furnace and integrated coal gasification and combined cycle (IGCC) are summarized. The relation between the blasting parameters and the output gas quantity, as well as caloric value is calculated based on mass and energy balance. The OBF-CC will be an efficient ironmaking and power generation process with higher energy efficiency and less pollution.
04/02033 Technology intervention to improve the energy efficiency and productivity of silk reeling sector
04/02034 Texturing industrial multicrystalline silicon solar cells Macdonald, D. H. et al, Solar Energy, 2004, 76, (1-3), 277-283. Three potential techniques for texturing commercial multicrystalline silicon solar cells are compared on the basis of reflectance measurements. Wet acidic texturing, which would be the least costly to implement, produces a modest improvement in reflection before antireflection coating and encapsulation, whereas maskless reactiveion etching texturing, and especially masked reactive-ion etched 'pyramids', generate a larger gain in absorption. After antireflection coating and encapsulation however, the differences between the methods are reduced. Short-circuit current measurements on wet acidic textured cells reveal that there is a significant additional current gain above that expected from the reduced reflection. This is attributed to both light-trapping and oblique coupling of incident light into the cell, resulting in generation closer to the junction.
04/02031 Release of alkali salts and coal volatiles affecting internal components in fluidized bed combustion systems del Campo, E. A.. et al. Revista de Metalurgia, 2003, 15-22. In spite of the potential advantages of atmospheric fluidized bed systems, experience has proved that, under certain environments and operating conditions, a given material employed for internal components could lead to catastrophic events. In this study, an attempt is made to establish material selection and operational criteria that optimize performance and availability based on theory considerations of the bed hydrodynamics, thermodynamic and combustion process. The theory results may indicate that, for high-volatile coals with particle diameters (de) of 1-3 m m and sand particle size (d~) of 0.674 ram, a considerable proportion of alkali chlorides may be transferred into the freeboard region of fluidized bed combustors as vapour phase, at bed temperatures (Tb) < 840°C, excess air (XSA) < 20%, static bed height (Hg) < 0.2 m and fluidizing velocity (Uo) < 1 m/s. Under these operating conditions, a high alkali deposition may be expected to occur in heat exchange tubes located above the bed. Conversely, when the combustors operate at Tb > 890°C and XSA > 30%, a high oxidation rate of the in-bed tubes may be present. Nevertheless, for these higher Tb value sand XSA < 10%, corrosion attack of metallic components, via sulfidation, would occur since the excessive gas-phase combustion within the bed induced a local oxygen depletion.
04/02032 Simulation of the gas flow distribution in the inlet chamber of the conventional and bathtub TLE Jekerle, J. American Institute of Chemical Engineers, 2003, 1394~1420. The bathtub transfer line exchanger differs from the conventional transfer line exchanger (TLE) in the arrangement of the tubes and the shape of the gas inlet chamber. Multiple gas inlet nozzles, reduced volume and an optimized internal shape of the gas inlet chamber have a favourable effect on the gas velocity profile, residence time of gas and deposits of coke. Numerous computational f u i d dynamic (CFD)
280 Fuel and Energy Abstracts July 2004
04/02035 The fiber optic system detecting the type of burned fuel in power boilers Wojcik, W. et al. Proceedings of SPIE - The International Society for Optical Engineering, 2003, 5028, (8), 131-135. The study presents the method of detecting the type of burned fuel in industrial conditions. Wavelet transforms were applied for th e signals corresponding to pulsation of chosen flame zone.
04/02036 Trace elements in circulating fluidized bed combustion of coal Zhang, J. et al. Ranshao Kexue Yu Jishu, 2003, 9, (1), 64-67. (In Chinese) For the better understanding of the partitioning behaviours of trace elements and their emissions with or without additive during circulating fluidized bed (CFB) combustion of coal, the coal was burned in a small CFB combustor. Coal samples, including CFB ash, magnetic ash in CFB ash, ash from chimney after dust remover and spraying water from chimney, were collected and analysed using ICP-AES, AFS, INAA, ICS and CV-AAS. The experimental result shows that the trace elements (As, Sb, Pb, Cu, Be, Zn) are enriched substantially in the fine particles of CFB ash, and Pb, As, Sb, Se, Th, Ni, Cr are enriched in the magnetic ash in CFB ash. In the ash from the chimney after dust removal, Zn, As, P, Ni, Cr, Mo, Be, Pb, Th, Hg, F are enriched while Nb, Rb, Zr are obviously deficient. With sulfur capture additive, the contents of As, Se, Sb, Zn in the fine particles of CFB ash decrease, and the contents of As, Se, Li, Be, Mo, Cr, Co, Ni in the ash from chimney after dust remover and the contents of Cu, Zn, Cr, Pb, Co, Ni, F, and Se in the spraying water from chimney decrease. Additives can control the emission of some potentially hazardous trace elements.