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04029 Trace element behavior during combustion of different coals in an experimental furnace
10
Thermogravimetric study of the pyrolysis of two Chinese coals under pressure
97lO4026
Sun, C. L. et al. Fuel, 1997, 76, (7), 639-644. Four size fractions of two Chinese coals, Hanqiao bituminous and Yuanquan anthracite, were used in a thermogravimetric study under pressure. The experimental results show that coal pyrolysis at elevated pressure occurs in two stages. In the first stage pressure has almost no effect on product yields. Obvious effect, however, was witnessed in the second stage, whereas the temperature effect can be negligible. The influence of particle size and heating rate under pressure was also studied and a mathematical model for large coal particles, which considers the temperature gradients within the particles and pressure effects, is proposed. The model predicts the experimental results with sufficient accuracy.
Trace element behavior during combustion 9?/04029 different coals in an experimental furnace
Trace metal capture by various sorbents during 97m403a fluidized-bed coal combustion Ho, T. C. et al. Proc. Int, Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 877888. The potential for employing suitable sorbents to capture toxic trace metallic substances during fluidized-bed coal combustion was explored. Metal capture experiments were carried out in a 25.4 mm quartz fluidized-bed combustor enclosed in an electric furnace. Cadmium, lead, chromium, arsenic and selenium were used, and the sorbents tested included bauxite, zeolite and lime. Possible metal-sorbent reactions were also identified through chemical equilibrium calculations, based on the minimization of system free energy. The observed experimental results indicated that metal capture by sorbents can be as high as 88% depending on the metal species and sorbent involved. Results from thermodynamic equilibrium simulations suggested the formation of metal-sorbent compounds such as Pb,SiOl(s) and CdSiOJ(s) under the combustion conditions.
Using low cost staged combustion to fire coal fines 97104031 co-fire coal/waste ‘a low cost fuel and technology strategy’ Murrell, F. _I. and Ashworth, R. A. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22. 617-626. When fired as a coal-water slurry fuel in wall-fired boilers, coal pond fines utilization is economically advantageous with staged combustor technology. The price differential between raw pond coal fines and processed fines offsets the increased capital cost for the staged combustion system. The CMRETM combustor technology also provides the added potential for SO* emissions reduction through the addition of hydrated lime or limestone to capture sulfur under the reducing condition of the first stage of combustion.
model of coal
Radomiak, H. Gospod. Paliwami Energ., 1996, 44, (8), 8-10. (In Polish) Distributions of 0, CO, COz, and temperature were calculated for combustion of a single coal particle in a circulating fluidized bed for gas phase velocity l-8 m/s. A model was used and the calculation results compared with measured values.
The Volvo high speed generation hybrid drive and 97104033 associated combustion system Sjiiblom, B. and Rehn, J. Energy Convers. Mgmt, 1997, 38, (lo-13), 12251235. As yet, attempts to find an alternative automotive power source to the Otto and Diesel engines have been largely unsuccessful. One alternative which has long been considered is the gas turbine; another is electric drive. The combination of these two in a hybrid system presents new opportunities and drives of this type are currently under trial in vehicles such as the Volvo Environmental Concept Car. The development of high-speed generators and efficient electric motors has played a decisive role in the success of this new concept. The Volvo hybrid drive and its characteristics are described along with another unique key component: the combustion system. A unique low-emission design has been developed for minimum emission levels. The combustion chamber employs the lean-premixed-pre-vaporized technique: the fuel is vaporized and mixed intimately with air prior to combustion, lowering the flame temperature and minimizing NO, forma-
and propulsion,
electrical vehicles)
tion. The gas turbine emission levels are so low that it will be possible to build a high speed generation drive with lower emission levels than the ULEV limits applicable in the USA.
10
ENGINES Power Generation and Propulsion, Electrical Vehicles
of
Baldacci. A. et ul. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1995, 20, 1 I22. The ENEL experimental programme (CATOCA project) aims to investigate the relationship between the coal characteristics and its behaviour during combustion. The experiments have been carried out in a 50 kWt vertical furnace equipped with a pulverized coal burner. The operating conditions of the plant were optimized in order to reach the best practical combustion efficiency and maintained as steady as possible for all the tests. Over 60 elements in fuels and related particulate matter were analysed by ICP/MS and IC for seven coals of different geographical origin and rank. Fourteen elements characterized by a tendency to transfer into stack gas as vapour phase, were sampled. A dedicated system named TRIS (TRace Inorganic Sampler), mainly consisting of a cooled train of solid adsorbers, was adopted. The analyses were performed by INAA. The concentrations of the elements in the stack gas, both in the particulate matter and in the vapour phase, are reported for all types of coal. The volatilization degree and the distribution between solid and vapour phase for each different coal are also included.
97104032 Verification of a mathematical combustion in a circulating fluidized bed
Engines (power generation
97lQ4034
Coal-fired
advanced
gas turbine
systems
for
repowering Robson, F. L. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1996, 21, 427-438. A team led by United Technologies Research Center has been investigating High Performance Power Systems (HIPPS) under sponsorship of the DOE Pittsburgh Energy Technology Center. The prime objective of these investigations has been green field designs of highly efficient coal-fired power plants using High Temperature Advanced Furnaces (HITAF) to preheat combustion air for gas turbines. Much of the efficiency advantage of the HITAF approach can be realized in the repowering of older steam plants. The preliminary investigations of repowering coal-fired stations using the next generation aero-derivative gas turbine in combined cycle and Humid Air Turbine (HAT) configurations. An 100 MW + industrialised version of the Pratt & Whitney 4000 aero engine is the basis of intercooled gas turbine cycles which use both coal and natural gas to heat the gas turbine combustion air. How the heat from the intercooler and the turbine exhaust is used in repowering depends on the desired steam conditions and power level. 97lO4035 50,000 Hp coal slurry diesel engine Crippa, E. R. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1994, 19, 821-828. Two power strokes per cylinder per cycle are efficiently produced by the novel two-cycle design compared to a single power stroke of the current large stationary two and four-cycle diesel engines.
Control of blowby emissions and lubricating oil consumption in I.C. engines
97104036
Dhariwal, H. C. Energy Convers. Mgmt, 1997, 38, (IO-13), 1267-1274. A significant part of total hydrocarbon emission by an automobile arise from blowby emissions, but no effort has so far been made in Britain to control the same. Investigations in this field have been neglected to date and the literature available on blowby emissions investigation is very scarce. This paper deals with investigations on the control of blowby emissions in high power turbocharged diesel engines by positive crank case ventilation (PCV) system installation. The lubricating oil mist escaping with blowby gases is also quite significant. Feasibility of recovering this mist by installing a lubricating oil mist separator in the PCV system has been established. The results clearly show the blowby emissions can be effectively controlled with the help of PCV system. However, the cross-section area of the PCV pipe has to be adjusted according to the amount of blowby gases and the inflow of ventilating air through the breather. The lubricating oil mist in the blowby gases could be separated and the lubricating oil returned back to sump with the use of a mist separator installed in the PCV system. Retrofitting of the PCV system and lubricating oil mist separator, even on engines in service, is possible. 97m4037 Economic scales for first-generation biomass gasifier/gas turbine combined cycles fueled from energy plantations Larson, E. D. and Marrison, C. I. J. Eng. Gas Turbines Power, 1997, 119, (2), 285-290. The scales at which commercial, first-generation biomass integratedgasifierigas turbine combine cycle (BIGIGTCC) technology is likely to be most economic when fuelled by plantation-derived biomass are evaluated. First-generation BIGiGTCC systems are likely to be commercially available around the year 2000 and will be based on either pressurized or atmospheric-pressure gasification. The paper considers both plant configurations, with estimates of capital and operating costs drawn from published and other sources. Prospective costs of a farm-grown energy crop (switchgrass) delivered to a power plant are developed with the aid of a geographical information system (GIS) for agricultural regions in the North Central and Southeast US in the year 2000 and 2020. A simplified approach is applied to estimate the cost of delivering chipped eucalyptus from an existing plantation in Northeast Brazil. The ‘optimum’ capacity (MW,,,), defined as that which yields the minimum calculated cost of electricity (COE,), varies by region, due to differences in delivered biomass costs. With pressurized BlGiGTCC plants, MW,,, is in the range of 230320 MW for the sites considered.
Fuel and Energy Abstracts
September 1997 339
Thermogravimetric study of the pyrolysis of two Chinese coals under pressure
97lO4026
Sun, C. L. et al. Fuel, 1997, 76, (7), 639-644. Four size fractions of two Chinese coals, Hanqiao bituminous and Yuanquan anthracite, were used in a thermogravimetric study under pressure. The experimental results show that coal pyrolysis at elevated pressure occurs in two stages. In the first stage pressure has almost no effect on product yields. Obvious effect, however, was witnessed in the second stage, whereas the temperature effect can be negligible. The influence of particle size and heating rate under pressure was also studied and a mathematical model for large coal particles, which considers the temperature gradients within the particles and pressure effects, is proposed. The model predicts the experimental results with sufficient accuracy.
Trace element behavior during combustion 9?/04029 different coals in an experimental furnace
Trace metal capture by various sorbents during 97m403a fluidized-bed coal combustion Ho, T. C. et al. Proc. Int, Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 877888. The potential for employing suitable sorbents to capture toxic trace metallic substances during fluidized-bed coal combustion was explored. Metal capture experiments were carried out in a 25.4 mm quartz fluidized-bed combustor enclosed in an electric furnace. Cadmium, lead, chromium, arsenic and selenium were used, and the sorbents tested included bauxite, zeolite and lime. Possible metal-sorbent reactions were also identified through chemical equilibrium calculations, based on the minimization of system free energy. The observed experimental results indicated that metal capture by sorbents can be as high as 88% depending on the metal species and sorbent involved. Results from thermodynamic equilibrium simulations suggested the formation of metal-sorbent compounds such as Pb,SiOl(s) and CdSiOJ(s) under the combustion conditions.
Using low cost staged combustion to fire coal fines 97104031 co-fire coal/waste ‘a low cost fuel and technology strategy’ Murrell, F. _I. and Ashworth, R. A. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22. 617-626. When fired as a coal-water slurry fuel in wall-fired boilers, coal pond fines utilization is economically advantageous with staged combustor technology. The price differential between raw pond coal fines and processed fines offsets the increased capital cost for the staged combustion system. The CMRETM combustor technology also provides the added potential for SO* emissions reduction through the addition of hydrated lime or limestone to capture sulfur under the reducing condition of the first stage of combustion.
model of coal
Radomiak, H. Gospod. Paliwami Energ., 1996, 44, (8), 8-10. (In Polish) Distributions of 0, CO, COz, and temperature were calculated for combustion of a single coal particle in a circulating fluidized bed for gas phase velocity l-8 m/s. A model was used and the calculation results compared with measured values.
The Volvo high speed generation hybrid drive and 97104033 associated combustion system Sjiiblom, B. and Rehn, J. Energy Convers. Mgmt, 1997, 38, (lo-13), 12251235. As yet, attempts to find an alternative automotive power source to the Otto and Diesel engines have been largely unsuccessful. One alternative which has long been considered is the gas turbine; another is electric drive. The combination of these two in a hybrid system presents new opportunities and drives of this type are currently under trial in vehicles such as the Volvo Environmental Concept Car. The development of high-speed generators and efficient electric motors has played a decisive role in the success of this new concept. The Volvo hybrid drive and its characteristics are described along with another unique key component: the combustion system. A unique low-emission design has been developed for minimum emission levels. The combustion chamber employs the lean-premixed-pre-vaporized technique: the fuel is vaporized and mixed intimately with air prior to combustion, lowering the flame temperature and minimizing NO, forma-
and propulsion,
electrical vehicles)
tion. The gas turbine emission levels are so low that it will be possible to build a high speed generation drive with lower emission levels than the ULEV limits applicable in the USA.
10
ENGINES Power Generation and Propulsion, Electrical Vehicles
of
Baldacci. A. et ul. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1995, 20, 1 I22. The ENEL experimental programme (CATOCA project) aims to investigate the relationship between the coal characteristics and its behaviour during combustion. The experiments have been carried out in a 50 kWt vertical furnace equipped with a pulverized coal burner. The operating conditions of the plant were optimized in order to reach the best practical combustion efficiency and maintained as steady as possible for all the tests. Over 60 elements in fuels and related particulate matter were analysed by ICP/MS and IC for seven coals of different geographical origin and rank. Fourteen elements characterized by a tendency to transfer into stack gas as vapour phase, were sampled. A dedicated system named TRIS (TRace Inorganic Sampler), mainly consisting of a cooled train of solid adsorbers, was adopted. The analyses were performed by INAA. The concentrations of the elements in the stack gas, both in the particulate matter and in the vapour phase, are reported for all types of coal. The volatilization degree and the distribution between solid and vapour phase for each different coal are also included.
97104032 Verification of a mathematical combustion in a circulating fluidized bed
Engines (power generation
97lQ4034
Coal-fired
advanced
gas turbine
systems
for
repowering Robson, F. L. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1996, 21, 427-438. A team led by United Technologies Research Center has been investigating High Performance Power Systems (HIPPS) under sponsorship of the DOE Pittsburgh Energy Technology Center. The prime objective of these investigations has been green field designs of highly efficient coal-fired power plants using High Temperature Advanced Furnaces (HITAF) to preheat combustion air for gas turbines. Much of the efficiency advantage of the HITAF approach can be realized in the repowering of older steam plants. The preliminary investigations of repowering coal-fired stations using the next generation aero-derivative gas turbine in combined cycle and Humid Air Turbine (HAT) configurations. An 100 MW + industrialised version of the Pratt & Whitney 4000 aero engine is the basis of intercooled gas turbine cycles which use both coal and natural gas to heat the gas turbine combustion air. How the heat from the intercooler and the turbine exhaust is used in repowering depends on the desired steam conditions and power level. 97lO4035 50,000 Hp coal slurry diesel engine Crippa, E. R. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1994, 19, 821-828. Two power strokes per cylinder per cycle are efficiently produced by the novel two-cycle design compared to a single power stroke of the current large stationary two and four-cycle diesel engines.
Control of blowby emissions and lubricating oil consumption in I.C. engines
97104036
Dhariwal, H. C. Energy Convers. Mgmt, 1997, 38, (IO-13), 1267-1274. A significant part of total hydrocarbon emission by an automobile arise from blowby emissions, but no effort has so far been made in Britain to control the same. Investigations in this field have been neglected to date and the literature available on blowby emissions investigation is very scarce. This paper deals with investigations on the control of blowby emissions in high power turbocharged diesel engines by positive crank case ventilation (PCV) system installation. The lubricating oil mist escaping with blowby gases is also quite significant. Feasibility of recovering this mist by installing a lubricating oil mist separator in the PCV system has been established. The results clearly show the blowby emissions can be effectively controlled with the help of PCV system. However, the cross-section area of the PCV pipe has to be adjusted according to the amount of blowby gases and the inflow of ventilating air through the breather. The lubricating oil mist in the blowby gases could be separated and the lubricating oil returned back to sump with the use of a mist separator installed in the PCV system. Retrofitting of the PCV system and lubricating oil mist separator, even on engines in service, is possible. 97m4037 Economic scales for first-generation biomass gasifier/gas turbine combined cycles fueled from energy plantations Larson, E. D. and Marrison, C. I. J. Eng. Gas Turbines Power, 1997, 119, (2), 285-290. The scales at which commercial, first-generation biomass integratedgasifierigas turbine combine cycle (BIGIGTCC) technology is likely to be most economic when fuelled by plantation-derived biomass are evaluated. First-generation BIGiGTCC systems are likely to be commercially available around the year 2000 and will be based on either pressurized or atmospheric-pressure gasification. The paper considers both plant configurations, with estimates of capital and operating costs drawn from published and other sources. Prospective costs of a farm-grown energy crop (switchgrass) delivered to a power plant are developed with the aid of a geographical information system (GIS) for agricultural regions in the North Central and Southeast US in the year 2000 and 2020. A simplified approach is applied to estimate the cost of delivering chipped eucalyptus from an existing plantation in Northeast Brazil. The ‘optimum’ capacity (MW,,,), defined as that which yields the minimum calculated cost of electricity (COE,), varies by region, due to differences in delivered biomass costs. With pressurized BlGiGTCC plants, MW,,, is in the range of 230320 MW for the sites considered.
Fuel and Energy Abstracts
September 1997 339