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05275 Mechanisms of N2 formation from char combustion
09 96105262
Influence of combustion condltlons on nitrous oxide emlsslon from CFB combustion Liu, H. et a/., Hut&tong Ligong Daxue Xuebao, 1995, 23, (ll), 1-4. (In Chinese) Ten types of coal were tested on a bench-scale circulating fluidized bed combustion test bed to examine the influence of the excess air ratio and temperature on N,O and NO, emission. Experiments were also performed on a pilot-scale arculating fluidized bed combination facility to study the effect for the circulation ratio on N,O and NO, emission.
96105263 The influence of hydrodynamics on the performance of an Interconnected fluldlzed bed system for regenerative desulphurlzatlon In coal converslon processes Snip, 0. C. ef al., AlChE Symp. Ser., 1995, (308), 82-92. Describes an interconnected fluidized bed reactor system for regenerative sulphur capture during fluidized bed combustion of coal and coal gasification processes.
96105264
Influence of operatlng parameters on NO, and N,O axle1 proflles In a clrculatlng fluldlzed bed combustor
De Diego, L. F. et al., Fuel, Jun. 1996, 75, (8), 971-978. The paper reports an experimental investigation of the influence of operating parameters on the formation and reduction of NO, and N,O from coal combustion, carried out in a circulating fluidized bed combustor 6.2m high and 0.161 m i.d. The main operating parameters studied were temperature, excess air factor, secondary/total air ratio, limestone addition and coal particle size. It was found that the NO, emission increased whereas the N,O emission decreased when the temperature increased, but the effect of the temperature depended on the excess air factor.
96105265
Influences of flame-vortex lnteractlons on formatlon of oxldes of nltrogen In curved methane-alr dlffuslon flames Card, J. M. et al., Combustion & Flame, May 1996, 105, (3), 373-380. Previous work has identified a parabolic flamelet in a uniform flow as a useful model for studying flame-vortex interactions and has presented an asymptotic analysis of this flamelet structure for two-step reduced chemistry of the methane-air system. The paper addresses production rates of oxides of nitrogen in this flamelet by one-step reduced-chemistry descriptions of both thermal and prompt mechanisms, for both two-step and threestep methane-air reduced chemistry, and also reports some results of calculations of production rates with a full-chemistry description of planar counterflow flames, for purposes of comparison.
lnvestlgatlon of the combustion of particles of coal 96105266 Davini, P. et al., Fuel, Jul. 1996, 75, (9), 1083-1088. A thermogravimetric method was used to study the behaviour of seven pulverized commercial coals during the first insLants of their combustion and devolatilization and combustion of the corresponding chars. Their weight variations are related to the evolution of the surface characteristics of the carbonaceous materials. In particular, BET surface areas of the chars appear to be strictly related to the volatile matter of the parent coals and to the devolatilization conditions. A thermogravimetric reactivity parameter is suggested and related to the combustion efficiency obtained from pilot plant combustion data.
Laboratory study of N,O formatlon from “N-Iso96105267 tope-marked NO while burnlng char particles at FBC conditions Miettinen, H. Energy Fuels, 1996, 10, (l), 197-202. Presents a study of the effect of NO and CO concentrations in the inlet gas, as well as the effect of changing gas residence time within the fixed bed and after the fixed bed on the emission of N,O from char particles burning at single particle conditions. In order to distmguish between char nitrogen and NO from the inlet gas a “N-isotope-marked NO was used in the inlet gas. The experiments were carried out in a fixed bed reactor containing quartz sand to support the coal particles. The bituminous coal particles were devolatilized in situ prior to the actual combustion in an argon flow.
96105266
Lagranglan slmulatlon of a thln non-premlxed flame in the field of an asymmetric layer Knio, 0. M. et al.,
Combustion
& Flame, Jul. 1996, 106, (l), 41-61.
Development of an analytical, subgrid-scale non-premixed combustion model for simulation of two-dimensional reacting shear flow at conditions of fast chemistry is described. The model is based on generalization of the classical one-dimensional flamelet representation to multi-dimensional flow conditions, and incorporation of resulting combustion model into adaptive, Lagrangian vortex element techniques.
Combustion (burners, combustion systems)
96lO5269
Laser-Induced Incandescence callbratlon via gravlmetric sampling
Va2nPqe:gWal, R. L.
er al.,
Combustion
& Flame, Jun. 1996, 105, (4),
Absolutd calibration of laser-induced incandescence (LII) is demonstrated via comparison of LII signal intensities with gravimetrically determined soot volume fractions. This calibration technique does not rely upon calculated or measured optical characteristics of soot. The variation of the LII signal with gravimetrically measured soot volume fractions ranging from 0.078 to 1.1 ppm established the linearly of the calibration. With the high spatial and temporal resolution capabilities of laser-induced incandescence (LII!, the spatial and temporal fluctuations of the soot field within a gravimetric chimney were characterized. 96105270
Maceral and Its effects on pulverized-coal-derived char morphology
Zhang, J. et al., Ranshao Kexue Yu Jishu, 1995, 1, (3), 196-202. (In Chinese) Discusses a study of three types of pulverized-coal samples and their maceral-rich samples. The results of proximate and maceral analysis have shown that the distributions of macerals are not uniform in coal, which is influenced by coal rank. Also the effect of volatiles on coal combustion properties is related to the rank. There is a definite relation between fuel ratio and vitrinite reflectance.
96105271 Maceral characterlstlcs of pulverized coal for power generatlon bollers Yuan, J. et al., Gongcheng Rewuli Xuebao, 1995, 16, (3), 372-375. (In Chinese) The maceral characters are analyzed of pulverized coal obtained from power stations. It was found that the maceral composition has no direct correlations with the proximate and ultimate analysis. 96105272
A mathematical model for coal combustion In a fluIdlzed-bed combustor: particle size dlstrlbutlon effects
Reddy, G. V. et al., Indian J. Eng. Mater. Sci., 1995, 2, (5), 224-230. Describes the development of a three phase multistage mathematical model for combustion of coal in a fluidized bed. The model is based on three phase theory of fluidization and material balance for shrinking coal particles. The burning of coal is assumed to take place according to single film theory. The model has been used to predict the effect of particle size distribution on combustion efficiency, exit gas composition, carbon carry over rate, carbon load and combustion rate.
96105273 Mathematical modeling of a combustion chamber flred wlth South African coal Eichhorn, N. W. VDI-Ber., 1995, 1193, 95-102. (In German) The overall coal combustion process in the combustion chamber (for a 600 MW-capacity South African power plant) was simulated based on a zonetype model by W. Richter (1981), which calculates the heat transfer density to the furnace walls, the three-dimensional temperature distribution of combustion gases, coal and coke burnout, and heat release in the combustion chamber. Important model parameters include the chamber geometry, operating conditions, coal properties, properties of wall deposits, and the flow fields in the chamber. 96105274
Mathematical modeling of coal or oil-shale particle
combustion Wang, G. er al., Meiran Zhuanhua, 1995, 18, (3), 13-16. (In Chinese) The paper discusses the value of environmental protection of selfdesulphurization by ash produced through particle combustion of coal and oil-shale in a fluidized bed.
Mechanisms of N, formation from char combustion 96105275 Feng, B. et al., Energy Fuels, 1996, 10, (l), 203-208. Describes an experimental study on N,O and NO, emission from char combustion. Experiments have been carried out in a fixed bed reactor at 973-1323 K. Oxygen concentrations for combustion temperature, and char type have been found to have strong effects to both N,O and NO, emissions. 96105276
A mechanistic study of the formatlon of slags from Iron-rich coals
Ten Brink, H. M. et al., Fuel, Jun. 1996, 75, (8), 952-958. The mechanism of slag formation by minerals from iron-rich coals was investigated in the reproducible environment of a laboratory burner. Alumina plates were used as substrates on which the particles were deposited. To simulate the highly reducing atmosphere of a cyclone-type flame, the burner was fired with large excess of CO. The mineral fractions of a coal rich in pyrite and a coal rich in iron oxide were used. The pyrite (Fe&)-rich sample produced a low-viscosity slag from which the sulphur rapidly volatilized. The slag from the iron oxide-rich sample was also of low viscosity. The expected reduction of the iron oxide in the slags to elemental iron by the carbon monoxide did not occur.
Fuel and Energy Abstracts September 1996 369
Influence of combustion condltlons on nitrous oxide emlsslon from CFB combustion Liu, H. et a/., Hut&tong Ligong Daxue Xuebao, 1995, 23, (ll), 1-4. (In Chinese) Ten types of coal were tested on a bench-scale circulating fluidized bed combustion test bed to examine the influence of the excess air ratio and temperature on N,O and NO, emission. Experiments were also performed on a pilot-scale arculating fluidized bed combination facility to study the effect for the circulation ratio on N,O and NO, emission.
96105263 The influence of hydrodynamics on the performance of an Interconnected fluldlzed bed system for regenerative desulphurlzatlon In coal converslon processes Snip, 0. C. ef al., AlChE Symp. Ser., 1995, (308), 82-92. Describes an interconnected fluidized bed reactor system for regenerative sulphur capture during fluidized bed combustion of coal and coal gasification processes.
96105264
Influence of operatlng parameters on NO, and N,O axle1 proflles In a clrculatlng fluldlzed bed combustor
De Diego, L. F. et al., Fuel, Jun. 1996, 75, (8), 971-978. The paper reports an experimental investigation of the influence of operating parameters on the formation and reduction of NO, and N,O from coal combustion, carried out in a circulating fluidized bed combustor 6.2m high and 0.161 m i.d. The main operating parameters studied were temperature, excess air factor, secondary/total air ratio, limestone addition and coal particle size. It was found that the NO, emission increased whereas the N,O emission decreased when the temperature increased, but the effect of the temperature depended on the excess air factor.
96105265
Influences of flame-vortex lnteractlons on formatlon of oxldes of nltrogen In curved methane-alr dlffuslon flames Card, J. M. et al., Combustion & Flame, May 1996, 105, (3), 373-380. Previous work has identified a parabolic flamelet in a uniform flow as a useful model for studying flame-vortex interactions and has presented an asymptotic analysis of this flamelet structure for two-step reduced chemistry of the methane-air system. The paper addresses production rates of oxides of nitrogen in this flamelet by one-step reduced-chemistry descriptions of both thermal and prompt mechanisms, for both two-step and threestep methane-air reduced chemistry, and also reports some results of calculations of production rates with a full-chemistry description of planar counterflow flames, for purposes of comparison.
lnvestlgatlon of the combustion of particles of coal 96105266 Davini, P. et al., Fuel, Jul. 1996, 75, (9), 1083-1088. A thermogravimetric method was used to study the behaviour of seven pulverized commercial coals during the first insLants of their combustion and devolatilization and combustion of the corresponding chars. Their weight variations are related to the evolution of the surface characteristics of the carbonaceous materials. In particular, BET surface areas of the chars appear to be strictly related to the volatile matter of the parent coals and to the devolatilization conditions. A thermogravimetric reactivity parameter is suggested and related to the combustion efficiency obtained from pilot plant combustion data.
Laboratory study of N,O formatlon from “N-Iso96105267 tope-marked NO while burnlng char particles at FBC conditions Miettinen, H. Energy Fuels, 1996, 10, (l), 197-202. Presents a study of the effect of NO and CO concentrations in the inlet gas, as well as the effect of changing gas residence time within the fixed bed and after the fixed bed on the emission of N,O from char particles burning at single particle conditions. In order to distmguish between char nitrogen and NO from the inlet gas a “N-isotope-marked NO was used in the inlet gas. The experiments were carried out in a fixed bed reactor containing quartz sand to support the coal particles. The bituminous coal particles were devolatilized in situ prior to the actual combustion in an argon flow.
96105266
Lagranglan slmulatlon of a thln non-premlxed flame in the field of an asymmetric layer Knio, 0. M. et al.,
Combustion
& Flame, Jul. 1996, 106, (l), 41-61.
Development of an analytical, subgrid-scale non-premixed combustion model for simulation of two-dimensional reacting shear flow at conditions of fast chemistry is described. The model is based on generalization of the classical one-dimensional flamelet representation to multi-dimensional flow conditions, and incorporation of resulting combustion model into adaptive, Lagrangian vortex element techniques.
Combustion (burners, combustion systems)
96lO5269
Laser-Induced Incandescence callbratlon via gravlmetric sampling
Va2nPqe:gWal, R. L.
er al.,
Combustion
& Flame, Jun. 1996, 105, (4),
Absolutd calibration of laser-induced incandescence (LII) is demonstrated via comparison of LII signal intensities with gravimetrically determined soot volume fractions. This calibration technique does not rely upon calculated or measured optical characteristics of soot. The variation of the LII signal with gravimetrically measured soot volume fractions ranging from 0.078 to 1.1 ppm established the linearly of the calibration. With the high spatial and temporal resolution capabilities of laser-induced incandescence (LII!, the spatial and temporal fluctuations of the soot field within a gravimetric chimney were characterized. 96105270
Maceral and Its effects on pulverized-coal-derived char morphology
Zhang, J. et al., Ranshao Kexue Yu Jishu, 1995, 1, (3), 196-202. (In Chinese) Discusses a study of three types of pulverized-coal samples and their maceral-rich samples. The results of proximate and maceral analysis have shown that the distributions of macerals are not uniform in coal, which is influenced by coal rank. Also the effect of volatiles on coal combustion properties is related to the rank. There is a definite relation between fuel ratio and vitrinite reflectance.
96105271 Maceral characterlstlcs of pulverized coal for power generatlon bollers Yuan, J. et al., Gongcheng Rewuli Xuebao, 1995, 16, (3), 372-375. (In Chinese) The maceral characters are analyzed of pulverized coal obtained from power stations. It was found that the maceral composition has no direct correlations with the proximate and ultimate analysis. 96105272
A mathematical model for coal combustion In a fluIdlzed-bed combustor: particle size dlstrlbutlon effects
Reddy, G. V. et al., Indian J. Eng. Mater. Sci., 1995, 2, (5), 224-230. Describes the development of a three phase multistage mathematical model for combustion of coal in a fluidized bed. The model is based on three phase theory of fluidization and material balance for shrinking coal particles. The burning of coal is assumed to take place according to single film theory. The model has been used to predict the effect of particle size distribution on combustion efficiency, exit gas composition, carbon carry over rate, carbon load and combustion rate.
96105273 Mathematical modeling of a combustion chamber flred wlth South African coal Eichhorn, N. W. VDI-Ber., 1995, 1193, 95-102. (In German) The overall coal combustion process in the combustion chamber (for a 600 MW-capacity South African power plant) was simulated based on a zonetype model by W. Richter (1981), which calculates the heat transfer density to the furnace walls, the three-dimensional temperature distribution of combustion gases, coal and coke burnout, and heat release in the combustion chamber. Important model parameters include the chamber geometry, operating conditions, coal properties, properties of wall deposits, and the flow fields in the chamber. 96105274
Mathematical modeling of coal or oil-shale particle
combustion Wang, G. er al., Meiran Zhuanhua, 1995, 18, (3), 13-16. (In Chinese) The paper discusses the value of environmental protection of selfdesulphurization by ash produced through particle combustion of coal and oil-shale in a fluidized bed.
Mechanisms of N, formation from char combustion 96105275 Feng, B. et al., Energy Fuels, 1996, 10, (l), 203-208. Describes an experimental study on N,O and NO, emission from char combustion. Experiments have been carried out in a fixed bed reactor at 973-1323 K. Oxygen concentrations for combustion temperature, and char type have been found to have strong effects to both N,O and NO, emissions. 96105276
A mechanistic study of the formatlon of slags from Iron-rich coals
Ten Brink, H. M. et al., Fuel, Jun. 1996, 75, (8), 952-958. The mechanism of slag formation by minerals from iron-rich coals was investigated in the reproducible environment of a laboratory burner. Alumina plates were used as substrates on which the particles were deposited. To simulate the highly reducing atmosphere of a cyclone-type flame, the burner was fired with large excess of CO. The mineral fractions of a coal rich in pyrite and a coal rich in iron oxide were used. The pyrite (Fe&)-rich sample produced a low-viscosity slag from which the sulphur rapidly volatilized. The slag from the iron oxide-rich sample was also of low viscosity. The expected reduction of the iron oxide in the slags to elemental iron by the carbon monoxide did not occur.
Fuel and Energy Abstracts September 1996 369