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03998 Coal combustion furnace having fluidized bed using natural mineral as catalyst to improve combustion and flue gas discharge
09
Combustion
(burners, combustion
systems)
Using CQIM to evaluate the performance and economic impacts of gas co-firing at Conesville Unit 3 Arroyo, J. A. et al. FACT, 1996, 21, (Proceedings of the International
9w3993
Joint Power Generation Conference, Volume 1: Environmental Control/ Fuels and Combustion Technologies, 1996) 265-271. A case study on the performance and economic impacts of natural gas cofiring at American Electric Power’s Conesville Unit 3, originally designed to burn coal, was performed using the Coal Quality Impact Model (CQIM). Gas co-firing proved to be economically advantageous over coal firing. The design coal was evaluated at 0, 10, 25,50, and 75% gas co-firing at full-load conditions. Increased gas co-firing decreased the auxiliary power requirements and boiler efficiency. Due to boiler efficiency reduction, the net unit heat rate increased with increased gas co-firing. The worsening of the net unit heat rate was offset by improved availability, auxiliary power, and decreased SO2 emissions with increased gas co-firing. Based on the performance improvements and penalties predicted by CQIM, the total fuel-related costs were reduced with increasing gas co-firing. The annual fuel cost component increased as a result of slightly higher natural gas prices and an increase in the net unit heat rate; however, waste disposal, operation and maintenance costs, and replacement energy costs decreased with increased percentage of gas co-firing. The annual cost benefits associated with gas co-firing would have been much greater if (1) unit derates were experienced when 100% coal was burned, (2) the coal inventory, start-up, and turndown cost elements had been applicable, and (3) the cost of replacement energy had been higher. Therefore, co-firing natural gas can still offer potential benefits when the full benefits of gas cofiring are not applied.
09
Coal combustion furnace having fluidized bed using natural mineral as catalyst to improve combustion and flue gas discharge 90l03990
Ihashi, W. et al. Jpn. Kokai Tokkyo Koho JP 10 43,551 [98 43,551] (Cl. BOlD53/94), 17 Feb 1998, JP Appl. 961100,159, 22 Apr 1996, 6 pp. (In Japanese) The fluidized bed material includes acidic clays, activated clays, bauxite and/or activated bauxite to improve decomposition of NzO and hydrocarbons generated in the furnace during combustion.
Coal combustion in fluidized beds. Fluid-dynamic
98/03999
aspects Villaflor, G. V. et al. Inf. Tecnol., 1998, 9, (l), 19-24. (In Spanish) This paper presents a study into the applicability of combustion in fluidized beds for coal from Rio Turbio in Argentina. The flow dynamic aspects of the process have been considered, and fluidization curves for particles of different size were obtained. The minimum fluidization curves for particles of different size were thus obtained and from these curves, it is possible to find the minimum fluidization velocities. The use of Ergun’s equation to determine the minimum fluidization velocity for conditions different from the experimental ones is discussed. Some preliminary experiments to determined the fluidization conditions in mixed beds of coal and sand are also reported.
Cocombustion of sewage sludge in an industrial
9QlQ4QQQ
COMBUSTION Burners, Combustion
kinetic data of the fuel by special batch-tests in the bubbling fluidized bed. The influence of the biomass mixing rate and of the process parameters on the combustion and emission behaviour in the CFBC were also examined. The results of the investigations are presented and can find application in biomass co-combustion in industrial units.
power plant
Systems
Applications of combustion technologies of micropulverized coal
Thomas, G. Wasser, Abwasser Abfall, 1997, 18, 227-237. (In German) The paper examines the co-combustion of mechanical dehydrated sewage sludge in an industrial brown coal-fired plant in a circulating fluidized-bed firing (ZWS process). A brief report concerning the German regulations for the combustion of sewage sludge, with special emphasis on mercury removal. The resultant steam was used for power generation and process steam. Economical and ecological balances showed the advantages of the co-combustion of sewage sludge in a brown coal-fired plant.
98lQ3994
Nakamura, M. et al. Ishikawajima-Harima Giho, 1998, 38, (2), 124-129. (In Japanese) Combustion of micro-pulverized-coal of -20 pm (as opposed to 40-50 pm) mean particle size achieves decreased NO, emissions and unburnt combustibles, also making lower excess air ratio operation possible. The Hekinan Thermal Power Station No. 3 Unit of Chubu Electric Power Co. Inc., has confirmed such effects of micro-pulverized coal combustion. An economic estimation verified that micro-pulverized coal combustion also reduced unit running costs. For micro-pulverized coal in a domestic industrial boiler, good performance regarding pulverized coal fineness and capacity has been achieved.
Applied laser spectroscopy in combustion devices 98103995 Sick, V. and Wolfrum, J. Lecf. Notes Phys., 1997, 499, 271-281. Active control of industrial combustion systems is possible with laser spectroscopy. Examples are given. A case study of fluidlzed-bed combustion of wood/ coal mixtures. Part A. The effect of wood particle size
98/03996
Helmer, W. A. et al. For. Prod. J., 1998, 48, (3) 46-49. Firing of wood/coal mixtures offers many advantages over the burning of each fuel individually. The effect of co-firing these fuels has not been adequately studied. Supplied from a short-rotation biomass farm, debarked silver maple wood was simultaneously burned with high sulfur (3%) Illinois bituminous coal in a small-diameter fluidized bed combustor. With an increasing percentage of wood in the mixture, SOz emissions were slightly reduced. Wood particle size difference, on the other hand, had little effect on NO, emissions. With respect to the generated SOz and NO, emissions, combustion temperature and excess air were probably more crucial combustion parameters.
Circulatln fluidized bed combustion (CFBC) of brown coal during mixBng up biomass
99iQ4QQl
Cocombustion of sewage sludge
Thome-Kozmiensky, K. J. Ber. Wasserguete Abfallwirtsch., Tech. Univ. Muenchen, 1998, 137, 321-369. (In German) Examples are provided for the co-combustion of sewage sludge in waste incinerators, circulating fluidized-bed firing of lignite-fired power stations, slag tap firing of coal-fired power stations and in cement, brick, and asphalt manufacture. For the different process variants, process engineering, operation, energy balances, emissions and costs are outlined.
Cofiring waste biofuels and coal for emissions
9QlQ4QQ2
reduction Brouwer, 2nd,
1995,
J. ef
al.
Proc. Biomass
Conf. Am.: Energy, Environ.,
Agric. Ind.,
390-399.
In order to evaluate the emissions reduction possible while firing coal blended with several different biofuels, combustion tests were performed in two pilot-scale combustion facilities. Pulverized coal fired boilers and stoker coal fired boilers were simulated. The pulverized coal-fired studies investigated the use of waste hardwood and softwood with pulverized coal or the use of the biofuels as potential reburning fuels. The use of these wood wastes is attractive because: wood contains little nitrogen and virtually no sulfur; wood is a regenerable biofuel; and wood utilization results in a net reduction in COz emissions. The wood reburning results indicate a reduction of 50-60% NO with -10% wood heat input. Co-firing of wood with pulverized coal, however, did not lead to significant NO reductions with the current low NO, burner configuration. The stoker programme investigated barriers for the successful blending of coal with waste railroad ties. The results demonstrate that NO emissions can be reduced by >50% without any significant increase in CO or THC emissions by the proper use of zoned reburning. Both programmes demonstrated several benefits of biofuel co-firing: lower operating costs due to reduced fuel prices, reduced waste disposal, reduced maintenance costs, reduced environmental costs and extension of the useful life of existing equipment.
98/03997
Neidel, W. et al. Dev. Thermochem. Biomass Convers., 1997, 2, 1358-1367. Edited by Bridgwater, A. V. and Boocock, D. G. B., Blackie, London, UK. It is possible to employ only the co-firing of biomass due to logistic problems, particularly in large CFBCs. So it is interesting to get knowledge about burnout and emission behaviour, as well as best working parameters to use biomass as co-combustion fuel in already existing units. Therefore the co-combustion of coal/biomass were investigated in bubbling and circulating fluidized beds. The experimental investigations has been realized by two test fluidized bed units, bubbling fluidized bed (diameter 100 mm, height 4000 mm) and circulating fluidized bed (diameter 100 mm, height 8000 mm) at the combustion laboratory of the University of Magdeburg. Biomass-wood, straw and a fast growing species (china reed)-were mixed with brown coal. The theoretical and experimental investigations attempted to determine the burnout characteristics and the
374
Fuel and Energy Abstracts
September 1998
Combustion and emission characteristics of a Thai lignite with a bubbling fluidized bed
9QlQ4QQ3
Wisut, W. et al.
Hokkaido
Kogvo Gijutsu Kenkyusho
Hokoku,
1998, 70, 14-
20.
A Thai lignite’s was investigated with a bench-scale fluidized-bed combustor to study the characteristics of combustion and emissions of NG,, NzO, and SOz. The bed temperature and fluidizing gas velocity were mamtained at 1070-1120 K and 1 m/s. Silica sand particles were used as a fluidized medium and Thai limestone was also used as an absorbent in the experiments for in situ SO2 removal. The measured combustion efficiency was >99% at the above bed temperature range. at different bed temperatures, the total conversion of fuel-nitrogen into NO, and NzO was almost constant, but individual emission levels were affected by bed temperature; as bed temperature increased, so did NO, emissions whereas NzO emissions decreased. Two-stage combustion was highly effective for
Combustion
(burners, combustion
systems)
Using CQIM to evaluate the performance and economic impacts of gas co-firing at Conesville Unit 3 Arroyo, J. A. et al. FACT, 1996, 21, (Proceedings of the International
9w3993
Joint Power Generation Conference, Volume 1: Environmental Control/ Fuels and Combustion Technologies, 1996) 265-271. A case study on the performance and economic impacts of natural gas cofiring at American Electric Power’s Conesville Unit 3, originally designed to burn coal, was performed using the Coal Quality Impact Model (CQIM). Gas co-firing proved to be economically advantageous over coal firing. The design coal was evaluated at 0, 10, 25,50, and 75% gas co-firing at full-load conditions. Increased gas co-firing decreased the auxiliary power requirements and boiler efficiency. Due to boiler efficiency reduction, the net unit heat rate increased with increased gas co-firing. The worsening of the net unit heat rate was offset by improved availability, auxiliary power, and decreased SO2 emissions with increased gas co-firing. Based on the performance improvements and penalties predicted by CQIM, the total fuel-related costs were reduced with increasing gas co-firing. The annual fuel cost component increased as a result of slightly higher natural gas prices and an increase in the net unit heat rate; however, waste disposal, operation and maintenance costs, and replacement energy costs decreased with increased percentage of gas co-firing. The annual cost benefits associated with gas co-firing would have been much greater if (1) unit derates were experienced when 100% coal was burned, (2) the coal inventory, start-up, and turndown cost elements had been applicable, and (3) the cost of replacement energy had been higher. Therefore, co-firing natural gas can still offer potential benefits when the full benefits of gas cofiring are not applied.
09
Coal combustion furnace having fluidized bed using natural mineral as catalyst to improve combustion and flue gas discharge 90l03990
Ihashi, W. et al. Jpn. Kokai Tokkyo Koho JP 10 43,551 [98 43,551] (Cl. BOlD53/94), 17 Feb 1998, JP Appl. 961100,159, 22 Apr 1996, 6 pp. (In Japanese) The fluidized bed material includes acidic clays, activated clays, bauxite and/or activated bauxite to improve decomposition of NzO and hydrocarbons generated in the furnace during combustion.
Coal combustion in fluidized beds. Fluid-dynamic
98/03999
aspects Villaflor, G. V. et al. Inf. Tecnol., 1998, 9, (l), 19-24. (In Spanish) This paper presents a study into the applicability of combustion in fluidized beds for coal from Rio Turbio in Argentina. The flow dynamic aspects of the process have been considered, and fluidization curves for particles of different size were obtained. The minimum fluidization curves for particles of different size were thus obtained and from these curves, it is possible to find the minimum fluidization velocities. The use of Ergun’s equation to determine the minimum fluidization velocity for conditions different from the experimental ones is discussed. Some preliminary experiments to determined the fluidization conditions in mixed beds of coal and sand are also reported.
Cocombustion of sewage sludge in an industrial
9QlQ4QQQ
COMBUSTION Burners, Combustion
kinetic data of the fuel by special batch-tests in the bubbling fluidized bed. The influence of the biomass mixing rate and of the process parameters on the combustion and emission behaviour in the CFBC were also examined. The results of the investigations are presented and can find application in biomass co-combustion in industrial units.
power plant
Systems
Applications of combustion technologies of micropulverized coal
Thomas, G. Wasser, Abwasser Abfall, 1997, 18, 227-237. (In German) The paper examines the co-combustion of mechanical dehydrated sewage sludge in an industrial brown coal-fired plant in a circulating fluidized-bed firing (ZWS process). A brief report concerning the German regulations for the combustion of sewage sludge, with special emphasis on mercury removal. The resultant steam was used for power generation and process steam. Economical and ecological balances showed the advantages of the co-combustion of sewage sludge in a brown coal-fired plant.
98lQ3994
Nakamura, M. et al. Ishikawajima-Harima Giho, 1998, 38, (2), 124-129. (In Japanese) Combustion of micro-pulverized-coal of -20 pm (as opposed to 40-50 pm) mean particle size achieves decreased NO, emissions and unburnt combustibles, also making lower excess air ratio operation possible. The Hekinan Thermal Power Station No. 3 Unit of Chubu Electric Power Co. Inc., has confirmed such effects of micro-pulverized coal combustion. An economic estimation verified that micro-pulverized coal combustion also reduced unit running costs. For micro-pulverized coal in a domestic industrial boiler, good performance regarding pulverized coal fineness and capacity has been achieved.
Applied laser spectroscopy in combustion devices 98103995 Sick, V. and Wolfrum, J. Lecf. Notes Phys., 1997, 499, 271-281. Active control of industrial combustion systems is possible with laser spectroscopy. Examples are given. A case study of fluidlzed-bed combustion of wood/ coal mixtures. Part A. The effect of wood particle size
98/03996
Helmer, W. A. et al. For. Prod. J., 1998, 48, (3) 46-49. Firing of wood/coal mixtures offers many advantages over the burning of each fuel individually. The effect of co-firing these fuels has not been adequately studied. Supplied from a short-rotation biomass farm, debarked silver maple wood was simultaneously burned with high sulfur (3%) Illinois bituminous coal in a small-diameter fluidized bed combustor. With an increasing percentage of wood in the mixture, SOz emissions were slightly reduced. Wood particle size difference, on the other hand, had little effect on NO, emissions. With respect to the generated SOz and NO, emissions, combustion temperature and excess air were probably more crucial combustion parameters.
Circulatln fluidized bed combustion (CFBC) of brown coal during mixBng up biomass
99iQ4QQl
Cocombustion of sewage sludge
Thome-Kozmiensky, K. J. Ber. Wasserguete Abfallwirtsch., Tech. Univ. Muenchen, 1998, 137, 321-369. (In German) Examples are provided for the co-combustion of sewage sludge in waste incinerators, circulating fluidized-bed firing of lignite-fired power stations, slag tap firing of coal-fired power stations and in cement, brick, and asphalt manufacture. For the different process variants, process engineering, operation, energy balances, emissions and costs are outlined.
Cofiring waste biofuels and coal for emissions
9QlQ4QQ2
reduction Brouwer, 2nd,
1995,
J. ef
al.
Proc. Biomass
Conf. Am.: Energy, Environ.,
Agric. Ind.,
390-399.
In order to evaluate the emissions reduction possible while firing coal blended with several different biofuels, combustion tests were performed in two pilot-scale combustion facilities. Pulverized coal fired boilers and stoker coal fired boilers were simulated. The pulverized coal-fired studies investigated the use of waste hardwood and softwood with pulverized coal or the use of the biofuels as potential reburning fuels. The use of these wood wastes is attractive because: wood contains little nitrogen and virtually no sulfur; wood is a regenerable biofuel; and wood utilization results in a net reduction in COz emissions. The wood reburning results indicate a reduction of 50-60% NO with -10% wood heat input. Co-firing of wood with pulverized coal, however, did not lead to significant NO reductions with the current low NO, burner configuration. The stoker programme investigated barriers for the successful blending of coal with waste railroad ties. The results demonstrate that NO emissions can be reduced by >50% without any significant increase in CO or THC emissions by the proper use of zoned reburning. Both programmes demonstrated several benefits of biofuel co-firing: lower operating costs due to reduced fuel prices, reduced waste disposal, reduced maintenance costs, reduced environmental costs and extension of the useful life of existing equipment.
98/03997
Neidel, W. et al. Dev. Thermochem. Biomass Convers., 1997, 2, 1358-1367. Edited by Bridgwater, A. V. and Boocock, D. G. B., Blackie, London, UK. It is possible to employ only the co-firing of biomass due to logistic problems, particularly in large CFBCs. So it is interesting to get knowledge about burnout and emission behaviour, as well as best working parameters to use biomass as co-combustion fuel in already existing units. Therefore the co-combustion of coal/biomass were investigated in bubbling and circulating fluidized beds. The experimental investigations has been realized by two test fluidized bed units, bubbling fluidized bed (diameter 100 mm, height 4000 mm) and circulating fluidized bed (diameter 100 mm, height 8000 mm) at the combustion laboratory of the University of Magdeburg. Biomass-wood, straw and a fast growing species (china reed)-were mixed with brown coal. The theoretical and experimental investigations attempted to determine the burnout characteristics and the
374
Fuel and Energy Abstracts
September 1998
Combustion and emission characteristics of a Thai lignite with a bubbling fluidized bed
9QlQ4QQ3
Wisut, W. et al.
Hokkaido
Kogvo Gijutsu Kenkyusho
Hokoku,
1998, 70, 14-
20.
A Thai lignite’s was investigated with a bench-scale fluidized-bed combustor to study the characteristics of combustion and emissions of NG,, NzO, and SOz. The bed temperature and fluidizing gas velocity were mamtained at 1070-1120 K and 1 m/s. Silica sand particles were used as a fluidized medium and Thai limestone was also used as an absorbent in the experiments for in situ SO2 removal. The measured combustion efficiency was >99% at the above bed temperature range. at different bed temperatures, the total conversion of fuel-nitrogen into NO, and NzO was almost constant, but individual emission levels were affected by bed temperature; as bed temperature increased, so did NO, emissions whereas NzO emissions decreased. Two-stage combustion was highly effective for