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00634 Diffusion-kinetic model of combustion of coal particles in a gas stream
09
99100631
Continuous
detonation
combustion
of fuel-air
99100636
Combustion
(burners,
The effect of coal particle
combustion
systems)
size on pyrolysis
equilibrium
mixtures
Bykovskii, F. A. et al. I%. Goreniya Vzryva, 1997, 33, (3), 120-131. (In Russian) In a disk-shaped chamber with a swirling flow, where a spinning detonation wave was generated, continuous detonation combustion of hydrogen- and methane-air mixtures as well as sprays of liquid fuels such as kerosene and diesel fuel was carried out. Before that, such a process could only be realized with oxygen as oxidizer.
Xue. Y. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (7), 32-36. In the pyrolysis of pulverized coal the particle size-of pulverized coal has some effect. The relation between pyrolysis equilibrium constants of block coal and pulverized coal was derived, and the effects of size, surface tension and density on the pyrolysis equilibrium was discussed. The results show that with decreasing coal particle size and the density and increasing surface tension the pyrolysis equilibrium constant increases.
99100632
99100639
Copyrolysis of coal with coke-oven gas
Liao, H. et al. Proc. Annu. Int. Pittsburgh Coal Conf.. 1997, 14, (8), l-7. It has been suggested that by using cheaper hydrogen-rich gas instead of pure hydrogen, the economy of the hydropyrolysis process is improved by reducing the hydrogen cost. Pyrolysis of Chinese Xianfeng lignite has been carried out with real coke-oven gas (COG) as reactive gases at 0.1-5 MPa and the final temperature of 650” with heating rate of 5-25 K/min in a IO g fixed-bed reactor. The effects of pressure on product yields under COG were investigated in detail and compared with coal pyrolysis with hydrogen at the same conditions. The results indicate that it is possible to use COG instead of pure hydrogen in hydropyrolysis, but that the experimental conditions must be adjusted to optimize the yields of the valuable chemicals.
99100633
Development
of melting furnace with oxy-coal
burner
Yamaguchi, R. et al. Ironmaking Conf. Proc., 1998, 57, 1821-1825. The efficient melting of scrap using only pulverized coal-oxygen combustion without electricity is the feature of this process. In 1995, the pilot scale melting furnace, which is 5 t/heat, was designed and constructed based on the experimental results by the bench scale furnace. When the experiments started the targets were to achieve about 55% in the total heat efficiency and above 94% in the yield of steel. The melting behaviour has been investigated to improve the heat efficiency and the steel yield and to get the optimum conditions. The operation periods of this process are classified into three steps. In step 1, as the heat transfer from the pulverized coal oxygen flame to scrap directly, the better efficiency can be obtained. So it is important to get a longer step 1 to increase the total heat efficiency. Most effective factors are the high temperature heating by optimization of burner conditions, and controlling of scrap falling down in the step 1. The aimed target of heat efficiency was attained, above 55% and yield, above 94%. In this paper, the latest data and also the possibility of the furnace are discussed.
99100634
Diffusion-kinetic particles in a gas stream
model of combustion
of coal
Bykov, V. 1. et al. Fiz. Goreniya Vztyua, 1997, 33, (4). 39-45. (In Russian) Taking into account heat exchange between coal particles and environment, heat transfer in the particle, release and combustion of volatiles, and combustion of solid residue, the dynamics of combustion of brown coal particles is modelled. A diffusion-kinetic model of combustion and calculation results of dynamics of this process are presented.
99100635
Dust powder containing ZnO as sulfur sorbent for coal combustion
Wang, R. et al. Huagong Yejin, 1998, 19, (l), 87-90. (In Chinese) A new kind of sulfur sorbent, metallurgical industrial dust containing ZnO, PbO, FeZOx is experimented, based on the analysis of the properties of conventional CaO-based sulfur sorbents and their desulfurization mechanism during coal combustion is experimented. The metallurgical industrial dust is a good sulfur sorbent for coal combustion.
The effect of acid treatment 99100636 evolution during pyrolysis in hydrogen
of coal on H2S
Soneda, Y. et al. Fuel, 1998, 77, (9/10), 907-911. Using g.c.-m.s., the amount of H$ evolved during pyrolysis was analysed for four types of raw coal samples, Taiheiyo, Datong, Wandoan and Mequinenza. These coals were treated with HNOJ or HF/HCl solution, in which inorganic sulfur was eliminated by the acid treatment. In the case of HNO,-treated samples, the evolution of H$ in the low temperature region, below 5OO”C, was reduced by the chemical oxidation. At high temperatures, the amount of HzS evolution from acid-treated coal was markedly increased compared to the raw coals, especially Taiheiyo and Wandoan, through the elimination of minerals. It was confirmed from X-ray fluorescence analysis and X-ray powder diffraction of coal and char that calcium in the raw coal has an important role for the fixation of sulfur during pyrolysis.
99100637
The effect of coal particle size on the heat of
combustion Xue, Y. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (2), 45-52. In this paper the relations between integral heat and differential heat of combustion for pulverized coal and the size of coal particle are obtained. The results show that particle size has some effect on coals heats of combustion; the smaller coal particle size, the greater the specific surface area and the specific surface energy, and the greater the heat value too. The differential heat of combustion for pulverized coal differs from the integral one.
The effect of coal particle size on the heat of
combustion Xue, Y. et al. Proc. Annu. Int. Pittshur~h Coal Conf., 19Y7, 14. (2). 48-52. In this paper the relations between integral heat and differential heat of combustion for pulverized coal and the size of coal particle are obtained. The results show that coal particle size has some effect on its heats of combustion; the smaller coal particle size, the greater the specific surface area and the specific surface energy. and the greater the heat value too. There is a difference between the differential heat of combustion for pulverized coal and the integral one.
99100640
Effect of dust type and operating conditions on the performance of high-temperature ceramic filters Ergudenler, A. et al. Proc. Int. Conf. Fluid. Bed Comhrr.vt., 1997, 14, (2), 1065-1073. In reducing and oxidizing environments with simulations of gasification and combustion conditions in an independent hot gas filtration test rig, the effect of dust type on the performance of three types of high temperature ceramic filters were investigated. Four different types of dusts obtained from commercial and pilot scale fluidized bed combustors and gasifiers were used with mass median diameters between 8.5-18.9 ,,rn, and hulk densities in the range of 177-523 kg/m.‘. The properties of the dust (i.e. particle density, particle size distribution and adhesiveness) had a significant effect on the rate of increase of the pressure drop, the cleaning pulse interval and the dust cake properties of filters. Difficult-to-clean dusts resulted in a high rate of increase in pressure drop resulting in a significant decrease in the pulse cleaning interval.
99100641 Effect of fuel binder and oxidiser particle diameter on the combustion of ammonium perchlorate based propellants Al-Harthi, A. and Williams, A. Fuel, 1998, 77, (13), 1451-1468. Studied were the decomposition and combustion behaviour of ammonium perchiorate (AP) and simple bi-propellant systems. In order to examine the role of binder on the combustion process three types of fuel binders were used. Paraffin wax was chosen as a simple model fuel, and AP/3-9% (mass%) paraffin wax mixtures were used. It was observed that the paraffin melted and volatilized to react with AP decomposition products in the gas phase. The same behaviour was observed for APipolyvinyl chloride propellant. In contrast, hydroxy terminated polybutadiene (HTPB) underwent condensed phase reactions before the reaction with AP occurred. In agreement with the kinetic data, the condensed-phase heat release was higher for AP/paraffin combustion than that of APiHTPB propellant. However, a lower burning rate was observed for the paraffin propellant and evidence is given that even at atmospheric pressure the role of gas-phase reactions is more pronounced.
99100642
Effect of high temperature separation from metallurgical coke
on inorganic sulfur
Legin-Kolar, M. and Radenovic, A. Kern Id. 1998, 47, (5), 193-197. To prepare the coke from coking coal with and without additives and to examine the sulfur fraction before and after high temperature treatment (HTT) of coke was the purpose of this research. Coke samples, produced from coking coal with and without additives (light atmospheric residue from petroleum refining and coal tar pitch), were heated up to maximum temperatures of 1200, 1600, 2000 and 2400°C at a temperature change rate of 10 and 30°C min-’ for two and for four hours. Changes in the sulfur fraction before and after temperature treatment of all cokes at these conditions were analysed. Types of inorganic sulfur compounds were also identified in the ashes of the coking coal and prepared cokes. The greatest degree of desulfurization of all cokes was achieved after two hours of thermal treatment at 2400°C and at a temperature change rate of 10°C min-‘. The greatest amount of sulfur was separated by heating up the coke produced from coal with the addition of coal tar pitch under those conditions. During H’IT the transformation and separation of some sulfur compounds took place. All of the inorganic sulfur was separated from the cokes produced with additives after heating at 1600°C; the sulfur determined in cokes in the temperature range between 1600 and 2400°C was of organic origin.
99100643
Effect of particle size on coal pyrolysis
Versan Kok, M. et al. J. Analysis Appl. Pyrolysis, 1998, 45, (2), 103-l 10. Under non-isothermal conditions with a heating rate of 10”Cimin at 20-600 under N2 atmosphere, the effect of particle size on coal pyrolysis was determined by thermogravimetry and differential thermogravimetry (TGI DTG). Different fractions of Cayirhan coal showed differences in TG/DTG curves, peak temperatures, and residue values. To determipe the kinetic parameters from TG/DTG curves the Arhennius model was used.
Fuel
and
Energy
Abstracts
January 1999 63
99100631
Continuous
detonation
combustion
of fuel-air
99100636
Combustion
(burners,
The effect of coal particle
combustion
systems)
size on pyrolysis
equilibrium
mixtures
Bykovskii, F. A. et al. I%. Goreniya Vzryva, 1997, 33, (3), 120-131. (In Russian) In a disk-shaped chamber with a swirling flow, where a spinning detonation wave was generated, continuous detonation combustion of hydrogen- and methane-air mixtures as well as sprays of liquid fuels such as kerosene and diesel fuel was carried out. Before that, such a process could only be realized with oxygen as oxidizer.
Xue. Y. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (7), 32-36. In the pyrolysis of pulverized coal the particle size-of pulverized coal has some effect. The relation between pyrolysis equilibrium constants of block coal and pulverized coal was derived, and the effects of size, surface tension and density on the pyrolysis equilibrium was discussed. The results show that with decreasing coal particle size and the density and increasing surface tension the pyrolysis equilibrium constant increases.
99100632
99100639
Copyrolysis of coal with coke-oven gas
Liao, H. et al. Proc. Annu. Int. Pittsburgh Coal Conf.. 1997, 14, (8), l-7. It has been suggested that by using cheaper hydrogen-rich gas instead of pure hydrogen, the economy of the hydropyrolysis process is improved by reducing the hydrogen cost. Pyrolysis of Chinese Xianfeng lignite has been carried out with real coke-oven gas (COG) as reactive gases at 0.1-5 MPa and the final temperature of 650” with heating rate of 5-25 K/min in a IO g fixed-bed reactor. The effects of pressure on product yields under COG were investigated in detail and compared with coal pyrolysis with hydrogen at the same conditions. The results indicate that it is possible to use COG instead of pure hydrogen in hydropyrolysis, but that the experimental conditions must be adjusted to optimize the yields of the valuable chemicals.
99100633
Development
of melting furnace with oxy-coal
burner
Yamaguchi, R. et al. Ironmaking Conf. Proc., 1998, 57, 1821-1825. The efficient melting of scrap using only pulverized coal-oxygen combustion without electricity is the feature of this process. In 1995, the pilot scale melting furnace, which is 5 t/heat, was designed and constructed based on the experimental results by the bench scale furnace. When the experiments started the targets were to achieve about 55% in the total heat efficiency and above 94% in the yield of steel. The melting behaviour has been investigated to improve the heat efficiency and the steel yield and to get the optimum conditions. The operation periods of this process are classified into three steps. In step 1, as the heat transfer from the pulverized coal oxygen flame to scrap directly, the better efficiency can be obtained. So it is important to get a longer step 1 to increase the total heat efficiency. Most effective factors are the high temperature heating by optimization of burner conditions, and controlling of scrap falling down in the step 1. The aimed target of heat efficiency was attained, above 55% and yield, above 94%. In this paper, the latest data and also the possibility of the furnace are discussed.
99100634
Diffusion-kinetic particles in a gas stream
model of combustion
of coal
Bykov, V. 1. et al. Fiz. Goreniya Vztyua, 1997, 33, (4). 39-45. (In Russian) Taking into account heat exchange between coal particles and environment, heat transfer in the particle, release and combustion of volatiles, and combustion of solid residue, the dynamics of combustion of brown coal particles is modelled. A diffusion-kinetic model of combustion and calculation results of dynamics of this process are presented.
99100635
Dust powder containing ZnO as sulfur sorbent for coal combustion
Wang, R. et al. Huagong Yejin, 1998, 19, (l), 87-90. (In Chinese) A new kind of sulfur sorbent, metallurgical industrial dust containing ZnO, PbO, FeZOx is experimented, based on the analysis of the properties of conventional CaO-based sulfur sorbents and their desulfurization mechanism during coal combustion is experimented. The metallurgical industrial dust is a good sulfur sorbent for coal combustion.
The effect of acid treatment 99100636 evolution during pyrolysis in hydrogen
of coal on H2S
Soneda, Y. et al. Fuel, 1998, 77, (9/10), 907-911. Using g.c.-m.s., the amount of H$ evolved during pyrolysis was analysed for four types of raw coal samples, Taiheiyo, Datong, Wandoan and Mequinenza. These coals were treated with HNOJ or HF/HCl solution, in which inorganic sulfur was eliminated by the acid treatment. In the case of HNO,-treated samples, the evolution of H$ in the low temperature region, below 5OO”C, was reduced by the chemical oxidation. At high temperatures, the amount of HzS evolution from acid-treated coal was markedly increased compared to the raw coals, especially Taiheiyo and Wandoan, through the elimination of minerals. It was confirmed from X-ray fluorescence analysis and X-ray powder diffraction of coal and char that calcium in the raw coal has an important role for the fixation of sulfur during pyrolysis.
99100637
The effect of coal particle size on the heat of
combustion Xue, Y. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (2), 45-52. In this paper the relations between integral heat and differential heat of combustion for pulverized coal and the size of coal particle are obtained. The results show that particle size has some effect on coals heats of combustion; the smaller coal particle size, the greater the specific surface area and the specific surface energy, and the greater the heat value too. The differential heat of combustion for pulverized coal differs from the integral one.
The effect of coal particle size on the heat of
combustion Xue, Y. et al. Proc. Annu. Int. Pittshur~h Coal Conf., 19Y7, 14. (2). 48-52. In this paper the relations between integral heat and differential heat of combustion for pulverized coal and the size of coal particle are obtained. The results show that coal particle size has some effect on its heats of combustion; the smaller coal particle size, the greater the specific surface area and the specific surface energy. and the greater the heat value too. There is a difference between the differential heat of combustion for pulverized coal and the integral one.
99100640
Effect of dust type and operating conditions on the performance of high-temperature ceramic filters Ergudenler, A. et al. Proc. Int. Conf. Fluid. Bed Comhrr.vt., 1997, 14, (2), 1065-1073. In reducing and oxidizing environments with simulations of gasification and combustion conditions in an independent hot gas filtration test rig, the effect of dust type on the performance of three types of high temperature ceramic filters were investigated. Four different types of dusts obtained from commercial and pilot scale fluidized bed combustors and gasifiers were used with mass median diameters between 8.5-18.9 ,,rn, and hulk densities in the range of 177-523 kg/m.‘. The properties of the dust (i.e. particle density, particle size distribution and adhesiveness) had a significant effect on the rate of increase of the pressure drop, the cleaning pulse interval and the dust cake properties of filters. Difficult-to-clean dusts resulted in a high rate of increase in pressure drop resulting in a significant decrease in the pulse cleaning interval.
99100641 Effect of fuel binder and oxidiser particle diameter on the combustion of ammonium perchlorate based propellants Al-Harthi, A. and Williams, A. Fuel, 1998, 77, (13), 1451-1468. Studied were the decomposition and combustion behaviour of ammonium perchiorate (AP) and simple bi-propellant systems. In order to examine the role of binder on the combustion process three types of fuel binders were used. Paraffin wax was chosen as a simple model fuel, and AP/3-9% (mass%) paraffin wax mixtures were used. It was observed that the paraffin melted and volatilized to react with AP decomposition products in the gas phase. The same behaviour was observed for APipolyvinyl chloride propellant. In contrast, hydroxy terminated polybutadiene (HTPB) underwent condensed phase reactions before the reaction with AP occurred. In agreement with the kinetic data, the condensed-phase heat release was higher for AP/paraffin combustion than that of APiHTPB propellant. However, a lower burning rate was observed for the paraffin propellant and evidence is given that even at atmospheric pressure the role of gas-phase reactions is more pronounced.
99100642
Effect of high temperature separation from metallurgical coke
on inorganic sulfur
Legin-Kolar, M. and Radenovic, A. Kern Id. 1998, 47, (5), 193-197. To prepare the coke from coking coal with and without additives and to examine the sulfur fraction before and after high temperature treatment (HTT) of coke was the purpose of this research. Coke samples, produced from coking coal with and without additives (light atmospheric residue from petroleum refining and coal tar pitch), were heated up to maximum temperatures of 1200, 1600, 2000 and 2400°C at a temperature change rate of 10 and 30°C min-’ for two and for four hours. Changes in the sulfur fraction before and after temperature treatment of all cokes at these conditions were analysed. Types of inorganic sulfur compounds were also identified in the ashes of the coking coal and prepared cokes. The greatest degree of desulfurization of all cokes was achieved after two hours of thermal treatment at 2400°C and at a temperature change rate of 10°C min-‘. The greatest amount of sulfur was separated by heating up the coke produced from coal with the addition of coal tar pitch under those conditions. During H’IT the transformation and separation of some sulfur compounds took place. All of the inorganic sulfur was separated from the cokes produced with additives after heating at 1600°C; the sulfur determined in cokes in the temperature range between 1600 and 2400°C was of organic origin.
99100643
Effect of particle size on coal pyrolysis
Versan Kok, M. et al. J. Analysis Appl. Pyrolysis, 1998, 45, (2), 103-l 10. Under non-isothermal conditions with a heating rate of 10”Cimin at 20-600 under N2 atmosphere, the effect of particle size on coal pyrolysis was determined by thermogravimetry and differential thermogravimetry (TGI DTG). Different fractions of Cayirhan coal showed differences in TG/DTG curves, peak temperatures, and residue values. To determipe the kinetic parameters from TG/DTG curves the Arhennius model was used.
Fuel
and
Energy
Abstracts
January 1999 63