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03992 Combustion characteristics of refuse-derived fuel (RDF)
09
Upper furnace deposition and plugging 97103981 Tran, H. Kraft Recovery Boilers, 1997, 245-282. Edited by Adams, T. N., TAPPI Press, Atlanta, GA. The author discusses the principles of deposition, deposit chemistry and characteristics, and the important factors that govern the rates of formation and removal of fly ash deposits in black liquor recovery boilers. Plugging of boilers is also discussed, as arc the possible measures for minimizing plugging. Utilization of coal-water fuels in fire-tube boilers 97103982 Morrison, D. K. et al. Proc. lnt. Tech. Conf: Coal Util. Fuel Syst., 1993, 18, 335-347. In co-operation with the University of Alabama and Jim Walter Resources, the Energy and Environmental Research Corporation (EER) was awarded a DOE contract to retrofit an existing fire-tube boiler with a coal-water slurry (CWS) firing system. Recognizing that combustion efficiency is the principle concern when firing slurry in fire-tube boilers, EER has targeted innovative approaches for improving carbon burnout without major boiler modifications. The boiler was successfully operated on coal-water slurry for 800 h. Carbon conversion was 90%. Further data evaluation, a market analysis, and final report preparation remain to be completed.
09
COMBUSTION Burners,
Combustion
Systems
97163983 Application study of rich/lean stability combustion technology of pulverized coal Zhou, J. et al. Proc. lnt. Tech. Conf Coal Util. Fuel Syst., 1997, 22, 47-57. Growing difference between peak load and valley load of electrical networks, necessitates the operation of many boilers at low load. Many power plants require that the boiler can operate steadily at low load without support oil to improve the economy and the safety of power plant. To meet these requirements a stability combustion technology named rich/lean combustion of pulverized coal was developed by ITPE of Zhejiang University. The pulverized coal in primary air is separated into two streams of air-coal flow; one is the rich pulverized coal stream and other is the lean pulverized coal stream. The rich pulverized coal stream is guided to the high temperature area facing the flame which contributes to ignition and flame stability of pulverized coal. The lean pulverized coal stream is guided to low temperature area located behind the flame and forms an air film near the furnace wall that reduces the slagging. This paper describes the design, construction and operation of a large gas-solid phase flow test facility to test separate efficiency of a specially designed guiding-separate equipment. 97103984 Ash behavior in coal combustion Campisi, A. et al. Chem. Aust., 1997, 64, (S), 8-11. Some aspects of ash behaviour are outlined along with the approaches to minimize operational problems in power plants.
used
97163985 Catalytic combustion in a reactor with periodic flow reversal. Part 1. Experimental results Ziifle, H. and Turek, T. Chemical Engineering and Processing, 1997, 36, (5), 327-340.
An experiment was carried out to investigate the use of a reactor with periodic flow reversal for catalytic incineration of the model pollutants carbon monoxide and propane. The most important parameters influencing the reactor operation were found to the catalytic activity, adiabatic temperature rise and heat transfer properties of the fixed bed. Higher catalytic activity leads to a decrease of the maximum temperature profile. Increasing reactant concentrations cause higher values of maximum temperature, temperature gradient in the reactor ends and mean temperature at reactor inlet outlet. A higher number of heat transfer units give rise to higher maximum temperature and higher temperature gradient in the reactor ends. The mean temperature at the reactor inlet/outlet, however, remains constant. Investigation of the ignition and extinction behaviour of the reactor has shown that a fixed bed with a lower number of heat transfer units requires higher reactant concentrations to maintain stable operation in the ignited state. 97103986 Catalytic combustion in a reactor with periodic flow reversal Part 2. Steady-state reactor model Ztifle, H. and Turek, T. Chemical Engineering and Processing, 1997, 36, (5), 341-352.
A reverse-flow reactor was analysed and compared to a conventional adiabatic fixed bed reactor with external heat exchanger. Both systems were found to be closely related. An additional system parameter, the centre of gravity of energy release caused by exothermic chemical reaction, is necessary. This can also be rationalized as the mean fraction of the reverse-
Combustion
(burners, combustion
systems)
flow reactor acting as a regenerative heat exchanger. A simple steady-state countercurrent reactor model is proposed. This model is capable of describing the influence of adiabatic temperature rise and heat transfer properties of the fixed bed of catalyst on mean reactant conversion and temperature profile in cycle steady state. Satisfactory agreement was generally observed between calculated and experimentally determined parameters. While discrepancies occur in the case of carbon monoxide oxidation, reactant conversion, maximum temperature and minimum concentration for stable operation in cycle steady state were accurately predicted for the propane oxidation. 97103987 Characteristics of pulverized-coal combustion in the system of oxygen/recycled flue gas combustion Kiga, T. et al. Energy Convers. Manage., 1997, 38, (Suppl., Proceedings of the Third International Conference on Carbon Dioxide Removal, 1996) S129-S134. The system of oxygen/recycled flue gas combustion for the removal of carbon dioxide from pulverized-coal firing power plants, combustion characteristics of pulverized coal and the heat absorption performance of boiler furnace were studied. To determine the ignition characteristics in the COs-rich atmosphere, the flame propagation speed of pulverized-coal cloud was measured in a microgravity combustion chamber. The results revealed that the flame propagation speed in an Oz/COz atmosphere was markedly low compared with that in Oz/Nz and OziAr. It was improved by increasing the Oz concentration. NO, and SOz emissions from the system were investigated in the industrial-scale combustion test facilities. NO, emission was not so greatly decreased by staging as air-blown combustion, while a considerable part of sulfur was absorbed in ash in the system. As for the heat absorption performance of the boiler furnace, a three-dimensional numerical analysis was applied to a large utility boiler furnace. A furnace designed for normal air-blown combustion was just large enough for the oxygen/recycled flue gas combustion with a realizable ratio of flue gas recycling. 97163988 Characterization of fiuidized bed combustion based on chaotic time series analysis of acoustic signals Tang, X. et al. Ranshao Kexue Yu lishu, 1997, 3, (1). 63-69. (In Chinese) Chaotic theory was used to study acoustic signals of fluidized bed combustion. The results reveal that the acoustic signals contain rich information of the fluidized-bed combustor (FBC). The FBC is a non-linear chaotic system. The attractor constructed from acoustic signals can be used to distinguish the behaviour patterns of different regimes such as coal sorts, fluidized air rate, and combustion zones. 97t63989 Coal testing for NO. and char burnout prediction in pulverized fuel combustion Gibbins, J. R. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1994, 19, 683-94.
A bench-scale test was developed from the wire-mesh apparatus. Heating rates and peak temperature comparable to those occurring during coal devolatilization in power plants can be achieved. In conjunction with standard micro-elemental analysis and TGA, measurements of char N content and reactivity can be obtained. This has the potential to assist in predicting the behaviour of coal in the utility plant. 97103990 Coal testing for NO, and char burnout prediction in pulverized fuel combustion Gibbins, J. R. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1994, 19, 683-694. A bench-scale test was developed from the wire-mesh apparatus. The test can apply heating rates and peak temperature comparable to those that occur during coal devolatilization in power plants. In conjunction with standard micro-elemental analysis and TGA, measurements of char N content and reactivity can be obtained with the potential to assist in predicting coal behaviour in the utility plant. 97103991 Combustion and inorganic emissions of ground waste tires Levendis, Y. et al. Proc. Int. Tech. Conf Coal Util. Fuel Syst., 1995, 20, 477-488.
The combustion characteristics and emissions of SO?, NO, and CO* gases from ground waste tires were experimentally investigated and results were compared with those obtained from burning pulverized coal. Laboratory bench-scale experiments were conducted in a drop-tube, laminar-flaw furnace, in air at fuel-lean conditions, at gas temperature ranging from 1300 K to 1600 K. Two particle size cuts were burned from both materials, 75-90 /Am and 180-212 pm. Blends of coal and tyre particles, at equal weight ratios, were also burned. A detailed presentation and analysis of the results can be found in this paper. 97103992 Combustion characteristics of refuse-derived fuel (PUP) Urabe, T. et al. Tokyo-to Seiso Kenkyusho Kenkyu Hokoku, 1995 (Pub. 1997), 142-148. (In Japanese) A batchwise burning test was carried out on extrusion-moulded RDF with O-10% Ca(OH)z and their starting powdered plastic wastes. The RDF with -5% Ca(OH)z was satisfactory in lowering CO and HCI concentrations in the burning gas and lengthening the time required for burning.
Fuel and Energy Abstracts
September
1997
335
Upper furnace deposition and plugging 97103981 Tran, H. Kraft Recovery Boilers, 1997, 245-282. Edited by Adams, T. N., TAPPI Press, Atlanta, GA. The author discusses the principles of deposition, deposit chemistry and characteristics, and the important factors that govern the rates of formation and removal of fly ash deposits in black liquor recovery boilers. Plugging of boilers is also discussed, as arc the possible measures for minimizing plugging. Utilization of coal-water fuels in fire-tube boilers 97103982 Morrison, D. K. et al. Proc. lnt. Tech. Conf: Coal Util. Fuel Syst., 1993, 18, 335-347. In co-operation with the University of Alabama and Jim Walter Resources, the Energy and Environmental Research Corporation (EER) was awarded a DOE contract to retrofit an existing fire-tube boiler with a coal-water slurry (CWS) firing system. Recognizing that combustion efficiency is the principle concern when firing slurry in fire-tube boilers, EER has targeted innovative approaches for improving carbon burnout without major boiler modifications. The boiler was successfully operated on coal-water slurry for 800 h. Carbon conversion was 90%. Further data evaluation, a market analysis, and final report preparation remain to be completed.
09
COMBUSTION Burners,
Combustion
Systems
97163983 Application study of rich/lean stability combustion technology of pulverized coal Zhou, J. et al. Proc. lnt. Tech. Conf Coal Util. Fuel Syst., 1997, 22, 47-57. Growing difference between peak load and valley load of electrical networks, necessitates the operation of many boilers at low load. Many power plants require that the boiler can operate steadily at low load without support oil to improve the economy and the safety of power plant. To meet these requirements a stability combustion technology named rich/lean combustion of pulverized coal was developed by ITPE of Zhejiang University. The pulverized coal in primary air is separated into two streams of air-coal flow; one is the rich pulverized coal stream and other is the lean pulverized coal stream. The rich pulverized coal stream is guided to the high temperature area facing the flame which contributes to ignition and flame stability of pulverized coal. The lean pulverized coal stream is guided to low temperature area located behind the flame and forms an air film near the furnace wall that reduces the slagging. This paper describes the design, construction and operation of a large gas-solid phase flow test facility to test separate efficiency of a specially designed guiding-separate equipment. 97103984 Ash behavior in coal combustion Campisi, A. et al. Chem. Aust., 1997, 64, (S), 8-11. Some aspects of ash behaviour are outlined along with the approaches to minimize operational problems in power plants.
used
97163985 Catalytic combustion in a reactor with periodic flow reversal. Part 1. Experimental results Ziifle, H. and Turek, T. Chemical Engineering and Processing, 1997, 36, (5), 327-340.
An experiment was carried out to investigate the use of a reactor with periodic flow reversal for catalytic incineration of the model pollutants carbon monoxide and propane. The most important parameters influencing the reactor operation were found to the catalytic activity, adiabatic temperature rise and heat transfer properties of the fixed bed. Higher catalytic activity leads to a decrease of the maximum temperature profile. Increasing reactant concentrations cause higher values of maximum temperature, temperature gradient in the reactor ends and mean temperature at reactor inlet outlet. A higher number of heat transfer units give rise to higher maximum temperature and higher temperature gradient in the reactor ends. The mean temperature at the reactor inlet/outlet, however, remains constant. Investigation of the ignition and extinction behaviour of the reactor has shown that a fixed bed with a lower number of heat transfer units requires higher reactant concentrations to maintain stable operation in the ignited state. 97103986 Catalytic combustion in a reactor with periodic flow reversal Part 2. Steady-state reactor model Ztifle, H. and Turek, T. Chemical Engineering and Processing, 1997, 36, (5), 341-352.
A reverse-flow reactor was analysed and compared to a conventional adiabatic fixed bed reactor with external heat exchanger. Both systems were found to be closely related. An additional system parameter, the centre of gravity of energy release caused by exothermic chemical reaction, is necessary. This can also be rationalized as the mean fraction of the reverse-
Combustion
(burners, combustion
systems)
flow reactor acting as a regenerative heat exchanger. A simple steady-state countercurrent reactor model is proposed. This model is capable of describing the influence of adiabatic temperature rise and heat transfer properties of the fixed bed of catalyst on mean reactant conversion and temperature profile in cycle steady state. Satisfactory agreement was generally observed between calculated and experimentally determined parameters. While discrepancies occur in the case of carbon monoxide oxidation, reactant conversion, maximum temperature and minimum concentration for stable operation in cycle steady state were accurately predicted for the propane oxidation. 97103987 Characteristics of pulverized-coal combustion in the system of oxygen/recycled flue gas combustion Kiga, T. et al. Energy Convers. Manage., 1997, 38, (Suppl., Proceedings of the Third International Conference on Carbon Dioxide Removal, 1996) S129-S134. The system of oxygen/recycled flue gas combustion for the removal of carbon dioxide from pulverized-coal firing power plants, combustion characteristics of pulverized coal and the heat absorption performance of boiler furnace were studied. To determine the ignition characteristics in the COs-rich atmosphere, the flame propagation speed of pulverized-coal cloud was measured in a microgravity combustion chamber. The results revealed that the flame propagation speed in an Oz/COz atmosphere was markedly low compared with that in Oz/Nz and OziAr. It was improved by increasing the Oz concentration. NO, and SOz emissions from the system were investigated in the industrial-scale combustion test facilities. NO, emission was not so greatly decreased by staging as air-blown combustion, while a considerable part of sulfur was absorbed in ash in the system. As for the heat absorption performance of the boiler furnace, a three-dimensional numerical analysis was applied to a large utility boiler furnace. A furnace designed for normal air-blown combustion was just large enough for the oxygen/recycled flue gas combustion with a realizable ratio of flue gas recycling. 97163988 Characterization of fiuidized bed combustion based on chaotic time series analysis of acoustic signals Tang, X. et al. Ranshao Kexue Yu lishu, 1997, 3, (1). 63-69. (In Chinese) Chaotic theory was used to study acoustic signals of fluidized bed combustion. The results reveal that the acoustic signals contain rich information of the fluidized-bed combustor (FBC). The FBC is a non-linear chaotic system. The attractor constructed from acoustic signals can be used to distinguish the behaviour patterns of different regimes such as coal sorts, fluidized air rate, and combustion zones. 97t63989 Coal testing for NO. and char burnout prediction in pulverized fuel combustion Gibbins, J. R. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1994, 19, 683-94.
A bench-scale test was developed from the wire-mesh apparatus. Heating rates and peak temperature comparable to those occurring during coal devolatilization in power plants can be achieved. In conjunction with standard micro-elemental analysis and TGA, measurements of char N content and reactivity can be obtained. This has the potential to assist in predicting the behaviour of coal in the utility plant. 97103990 Coal testing for NO, and char burnout prediction in pulverized fuel combustion Gibbins, J. R. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1994, 19, 683-694. A bench-scale test was developed from the wire-mesh apparatus. The test can apply heating rates and peak temperature comparable to those that occur during coal devolatilization in power plants. In conjunction with standard micro-elemental analysis and TGA, measurements of char N content and reactivity can be obtained with the potential to assist in predicting coal behaviour in the utility plant. 97103991 Combustion and inorganic emissions of ground waste tires Levendis, Y. et al. Proc. Int. Tech. Conf Coal Util. Fuel Syst., 1995, 20, 477-488.
The combustion characteristics and emissions of SO?, NO, and CO* gases from ground waste tires were experimentally investigated and results were compared with those obtained from burning pulverized coal. Laboratory bench-scale experiments were conducted in a drop-tube, laminar-flaw furnace, in air at fuel-lean conditions, at gas temperature ranging from 1300 K to 1600 K. Two particle size cuts were burned from both materials, 75-90 /Am and 180-212 pm. Blends of coal and tyre particles, at equal weight ratios, were also burned. A detailed presentation and analysis of the results can be found in this paper. 97103992 Combustion characteristics of refuse-derived fuel (PUP) Urabe, T. et al. Tokyo-to Seiso Kenkyusho Kenkyu Hokoku, 1995 (Pub. 1997), 142-148. (In Japanese) A batchwise burning test was carried out on extrusion-moulded RDF with O-10% Ca(OH)z and their starting powdered plastic wastes. The RDF with -5% Ca(OH)z was satisfactory in lowering CO and HCI concentrations in the burning gas and lengthening the time required for burning.
Fuel and Energy Abstracts
September
1997
335