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06352 Effects of heating rate and coal type on gas evolution during coal pyrolysis
09
Combustion
(burners,
combustion
systems)
96/0634l
Drop tube lnVeStigStlOn8 hlt0 the tat8 Of fuel nitrogen durlng coal COmbUStiOn Bonn, B. et al., Coal Sci. Technol., 1995, 24, 759-762.
96108352 Effect8 Of heating rat8 and Coal type On g88 evolutiOn durlng CO81 pyrOlySl8 Takarada, T. et al., Tetsu to Hagane, 1996,82, (5), 388-392. (In Japanese)
Four high-volatile bituminous coals were used to investigate the effect of different coal composition on the amount and release of fuel-nitrogen. The nitrogen content and functional groups depend on the exinite content; with increasing amounts of exinite both, the amount of total nitrogen, and the ratio of the pyrrolic form of nitrogen in the coal related to the pyridinic form as determined by XPS grow. Results from pyrolysis and combustion experiments indicate that residence time and temperature as the main influencing parameters are both interrelated.
In order to obtained a decisive conclusion on the effect of the heatmg rate on gas evolution behaviour during coal pyrolysis, the pyrolysis of coal was systematically investigated in thermo-balance using six coals which have different carbon contents ranging from 81 to 88 wt.%. The heating rate ranged from 3 to 300 Wmin. The evolution rates of CH,, GH,, C&, &, CO and CO, were measured.
Effect of mechsnlcal pressure durlng pyroly8lr on 96/06345 the enhsncrment of caking proprrtlrr of poorly coking coal Miura, K. et al., Tetsu to Hagane, 1996, 82, (5): 39943. (In Japanese)
Discusses the effect of pressure load on the carboruzation behaviour of coal by measuring gas formation rate and several solid properties, such as yield of THF solutions and pore volume distribution to clarify the mechanism by which coking properties are improved. By increasing pressure up to 40 MPa, the formation of % and CO was significantly suppressed, but the solid yield and the amount of THF solutions increased. Furthermore, the solid yield was found to decrease significantly for a poorly coking coal when pressure was released at 350-400°C. Effect of mlneral matter and oxldatlon on the evolu96106346 tion of low molecular welght compound8 durlng pyrolysle Mondragon, F. et al., Coal Sci. Technol., 1995, 24, 921-924.
The paper discusses the effects of mineral matter on the evolution of CH,, H,S, CO? and low molecular weight hydrocarbons during pyrolysis of coals. 96106347 Effect of rank on the oxldatlon rate of coal Landais, P. et al., Coal Sci. Technol., 1995, 24, 449-452. The paper describes how an immature coal was artifically matured in a confined pyrolyiss system and the pyrolysis products, representing major stages of coalification, as well as the raw coal were oxidized. Chloroform extracts and solid residues were analyzed to study the combined effects of oxidation and coalification. The results obtained suggest that although major oxidation effects could be recognized as rank independent, some parameters were typically rank-dependent. 96106346
Effect
of
spatial
avereglng
on
CARS-derived
96106353
Effects of lanltion 8nd wind on the transition to flame Spread ln a mlCrO&Svky SnVlrOnment M&rattan, K. B. et a/., Combusrion & Flame, Sep. 1996, 106, (4),
377-391. A two-dimensional, time-dependent model is developed describing ignition and the subsequent transition to flame spread over a thermally thin cellulosic sheet heated by external radiation in a microgravity environment. The effects of a slow external wind (O-5 cm/s), and of the flux distribution of the external radiation on the transition are studied mainly in an atmosphere of 30% oxygen concentration. 96106354
The effects of Ion-exchanged metals on the composition of brown coal tars Droduced In 8 fluldlzed bed reector Wornat, M. J. et al., Coal Sk. Technol., 1995,. 24, 917-920.
This study shows that as pyrolysis temperature IS increased, the aromatic portion of the tar produced from Yallourn brown coal changes from a complex mixture of substituted species to a less complex mixture of primarily unsubstituted aromatics. Parallel to this change is a depletion of the aromatic constituents containing ring nitrogen. The presence of calcium has some influence on the composition of the aromatic products. 96106355
Effect8 Of momentum nonequlllbrlum on fl8m8 and extlnctlon In the presence of Inert partIcIer M&hvdadze, G. M. et al., Combustion & Flame, Aug. 1996, 106, (3),
propagation
Numeridal simulation of premixed gas flame moving in the presence of inert particles are presented. The paper provides background information concerning the use of numerical methods employed that allow for elucidation of the effect of particles on the structure, dynamics and extinction of a premixed flame evolving in a closed planar channel. The results obtained for zero-gravity and full-gravity are compared.
Combustion & Flame, Sep. 1996,
Estimation of cooling tube locatlon In fluldlzed bed 96106356 Coal COmbuStOr8 through exergy 8nSlySl8 Eskin, N. and Kilic, A. Energy Cowers. Mgmt., Sep. 1996, 37, (9),
Effect of swirl on combustion in a short cylindrical E!iz%i: $F;:fi2D. and Hill, P. G. Combustion & Flame, Aug. 1996, 106, (3),
1453-1461. The paper presents the exergy analysis of fluidized bed coal combustors (FBCCs) under different arrangements of cooling tubes. Considering changes in the heat transfer coefficient due to the particle movement and coal combustion and drag coefficient changes due to the particle movement in the bed and in the freeboard, the second-law efficiency of combustors has been examined and the effect of cooling tube locations on effectiveness has been analyzed. The location of cooling tubes in an FBCC has been analyzed with exergy analysis of the combustor.
temperatures
Parameswaran, T. and Snelling, D. R. 106, (4), 511-514.
Combu&on of a swirling, stoichiometric, and homogeneous mixture of natural gas and air in a short cylindrical chamber has been studied experimentally and simulated numerically. Each mixture was given a steady-state swirling motion by a rotating roughened disc before being ignited as the centre of the chamber. By using discs of differing roughness and by varying the disc speed, the intensities of swirl and turbulence could be varied independently so that the effects on combustion of mixture turbulence and swirl-induced buoyancy could be separately examined. Combustion rate and overall chamber heat transfer were inferred from chamber pressuretime records. High-speed schlieren photography showed the effect of swirl on the early flame kernel. 96lO6360
EffeCtlVen888 Of high temperature pyrOlySl8 in SUlfur removal from coal Gryglewicz, G. Fuel Process. Technol., 1996, 46, (3), 217-226.
A series of Polish bituminous coals of different rank, contaiing 0.37-4.0 wt.% sulphur, was subjected to pyrolysis at 10000. A decreasing trend in the extent of sulphur removal by high-temperature pyrolysis was observed with increasing coal rank. The effectiveness of pyrolysis in sulphur removal appeared to be related to the proportion of the non-thiophenic sulphur to the total organic sulphur in the coal. 96106361 The effect8 of coflring natural gas and coal on sulfur retention In 88h Bayless, D. 5. er ai _ Combustion & Flame, Aug. 1996, 106, (3), 231-240. Under certain cond&ons, cofiring natural gas with coal has been shown to reduce SO, emissions beyond the reduction expected from simple replacement of sulphur-bearing coal. This enhanced reduction of sulphur emissions, known as sulphur leveraging, is believed to result from increased sulphur capture in coal ash. In this research, experiments with three coals, using size ranges from 90 to 106 urn and 125 to 150 urn, and furnace temperatures of 1300 and 1550 K, demonstrate the extent of sulphur leveraging through increased sulphur retention in ash when cofiring coal and natural gas.
96106357 An examlnatlon of burnlng profiles a8 8 tool to predlct the combustion behavior of coals Pisupati, S. V. Prepr. Pap.-Am. Chem. Sot., Div. Fuel Chem., 1996, 41, (l), 13-18. Burning profiles of a suite of coals ranging from fresh coals to severely weathered coals, and subbituminous coals and bituminous coals were obtained. Combustion efficiences were also determined in a drop tube reactor, 1000 lb/h research boiler, and a 15,000 lb/h industrial-scale demonstration boiler. A good correlation was obtained between the initial temperature and the combustion efficiency obtained under identical conditions. ExperImental analyels of a free fall reactor 96106356 Takahashi, H. et al., Coal Sci. Technol., 1995, 24, 985-988. This study used a free fall reactor to study three Japanese coals: Taiheiyo, Akabira and Miike coals. It was revealed that the free fall reactor enables 24-42 mesh Akabira coal to accumulate THF solubles in the char and melt, which was not seen by TG at 3 K/min for >-lo0 mesh particles. This phenomenon is clearly due to the larger heat and mass tranifer resistances associated with large particle sizes. The fate of chlorine In coal combustion 96106359 Pan, W. P. et al:, Coal Sci. Technol., 1995, 24, 815-818. HCl release profiles indicated that the evolution of chlorine as HCI as broad overlapping peaks between 250 and 600”. The HCl release rate reaches a third maximum at 300 and 400°, which matches closely with the second and the third water release peak. Another small peak around 750”is only observed for higher chlorine content coals. The main chemical forms of chlorine present in coal that have been proposed are inorganic chlorine and chlorine ions in brine and other water associated with the coal.
Fuel and Energy Abstract8
November
1996
447
Combustion
(burners,
combustion
systems)
96/0634l
Drop tube lnVeStigStlOn8 hlt0 the tat8 Of fuel nitrogen durlng coal COmbUStiOn Bonn, B. et al., Coal Sci. Technol., 1995, 24, 759-762.
96108352 Effect8 Of heating rat8 and Coal type On g88 evolutiOn durlng CO81 pyrOlySl8 Takarada, T. et al., Tetsu to Hagane, 1996,82, (5), 388-392. (In Japanese)
Four high-volatile bituminous coals were used to investigate the effect of different coal composition on the amount and release of fuel-nitrogen. The nitrogen content and functional groups depend on the exinite content; with increasing amounts of exinite both, the amount of total nitrogen, and the ratio of the pyrrolic form of nitrogen in the coal related to the pyridinic form as determined by XPS grow. Results from pyrolysis and combustion experiments indicate that residence time and temperature as the main influencing parameters are both interrelated.
In order to obtained a decisive conclusion on the effect of the heatmg rate on gas evolution behaviour during coal pyrolysis, the pyrolysis of coal was systematically investigated in thermo-balance using six coals which have different carbon contents ranging from 81 to 88 wt.%. The heating rate ranged from 3 to 300 Wmin. The evolution rates of CH,, GH,, C&, &, CO and CO, were measured.
Effect of mechsnlcal pressure durlng pyroly8lr on 96/06345 the enhsncrment of caking proprrtlrr of poorly coking coal Miura, K. et al., Tetsu to Hagane, 1996, 82, (5): 39943. (In Japanese)
Discusses the effect of pressure load on the carboruzation behaviour of coal by measuring gas formation rate and several solid properties, such as yield of THF solutions and pore volume distribution to clarify the mechanism by which coking properties are improved. By increasing pressure up to 40 MPa, the formation of % and CO was significantly suppressed, but the solid yield and the amount of THF solutions increased. Furthermore, the solid yield was found to decrease significantly for a poorly coking coal when pressure was released at 350-400°C. Effect of mlneral matter and oxldatlon on the evolu96106346 tion of low molecular welght compound8 durlng pyrolysle Mondragon, F. et al., Coal Sci. Technol., 1995, 24, 921-924.
The paper discusses the effects of mineral matter on the evolution of CH,, H,S, CO? and low molecular weight hydrocarbons during pyrolysis of coals. 96106347 Effect of rank on the oxldatlon rate of coal Landais, P. et al., Coal Sci. Technol., 1995, 24, 449-452. The paper describes how an immature coal was artifically matured in a confined pyrolyiss system and the pyrolysis products, representing major stages of coalification, as well as the raw coal were oxidized. Chloroform extracts and solid residues were analyzed to study the combined effects of oxidation and coalification. The results obtained suggest that although major oxidation effects could be recognized as rank independent, some parameters were typically rank-dependent. 96106346
Effect
of
spatial
avereglng
on
CARS-derived
96106353
Effects of lanltion 8nd wind on the transition to flame Spread ln a mlCrO&Svky SnVlrOnment M&rattan, K. B. et a/., Combusrion & Flame, Sep. 1996, 106, (4),
377-391. A two-dimensional, time-dependent model is developed describing ignition and the subsequent transition to flame spread over a thermally thin cellulosic sheet heated by external radiation in a microgravity environment. The effects of a slow external wind (O-5 cm/s), and of the flux distribution of the external radiation on the transition are studied mainly in an atmosphere of 30% oxygen concentration. 96106354
The effects of Ion-exchanged metals on the composition of brown coal tars Droduced In 8 fluldlzed bed reector Wornat, M. J. et al., Coal Sk. Technol., 1995,. 24, 917-920.
This study shows that as pyrolysis temperature IS increased, the aromatic portion of the tar produced from Yallourn brown coal changes from a complex mixture of substituted species to a less complex mixture of primarily unsubstituted aromatics. Parallel to this change is a depletion of the aromatic constituents containing ring nitrogen. The presence of calcium has some influence on the composition of the aromatic products. 96106355
Effect8 Of momentum nonequlllbrlum on fl8m8 and extlnctlon In the presence of Inert partIcIer M&hvdadze, G. M. et al., Combustion & Flame, Aug. 1996, 106, (3),
propagation
Numeridal simulation of premixed gas flame moving in the presence of inert particles are presented. The paper provides background information concerning the use of numerical methods employed that allow for elucidation of the effect of particles on the structure, dynamics and extinction of a premixed flame evolving in a closed planar channel. The results obtained for zero-gravity and full-gravity are compared.
Combustion & Flame, Sep. 1996,
Estimation of cooling tube locatlon In fluldlzed bed 96106356 Coal COmbuStOr8 through exergy 8nSlySl8 Eskin, N. and Kilic, A. Energy Cowers. Mgmt., Sep. 1996, 37, (9),
Effect of swirl on combustion in a short cylindrical E!iz%i: $F;:fi2D. and Hill, P. G. Combustion & Flame, Aug. 1996, 106, (3),
1453-1461. The paper presents the exergy analysis of fluidized bed coal combustors (FBCCs) under different arrangements of cooling tubes. Considering changes in the heat transfer coefficient due to the particle movement and coal combustion and drag coefficient changes due to the particle movement in the bed and in the freeboard, the second-law efficiency of combustors has been examined and the effect of cooling tube locations on effectiveness has been analyzed. The location of cooling tubes in an FBCC has been analyzed with exergy analysis of the combustor.
temperatures
Parameswaran, T. and Snelling, D. R. 106, (4), 511-514.
Combu&on of a swirling, stoichiometric, and homogeneous mixture of natural gas and air in a short cylindrical chamber has been studied experimentally and simulated numerically. Each mixture was given a steady-state swirling motion by a rotating roughened disc before being ignited as the centre of the chamber. By using discs of differing roughness and by varying the disc speed, the intensities of swirl and turbulence could be varied independently so that the effects on combustion of mixture turbulence and swirl-induced buoyancy could be separately examined. Combustion rate and overall chamber heat transfer were inferred from chamber pressuretime records. High-speed schlieren photography showed the effect of swirl on the early flame kernel. 96lO6360
EffeCtlVen888 Of high temperature pyrOlySl8 in SUlfur removal from coal Gryglewicz, G. Fuel Process. Technol., 1996, 46, (3), 217-226.
A series of Polish bituminous coals of different rank, contaiing 0.37-4.0 wt.% sulphur, was subjected to pyrolysis at 10000. A decreasing trend in the extent of sulphur removal by high-temperature pyrolysis was observed with increasing coal rank. The effectiveness of pyrolysis in sulphur removal appeared to be related to the proportion of the non-thiophenic sulphur to the total organic sulphur in the coal. 96106361 The effect8 of coflring natural gas and coal on sulfur retention In 88h Bayless, D. 5. er ai _ Combustion & Flame, Aug. 1996, 106, (3), 231-240. Under certain cond&ons, cofiring natural gas with coal has been shown to reduce SO, emissions beyond the reduction expected from simple replacement of sulphur-bearing coal. This enhanced reduction of sulphur emissions, known as sulphur leveraging, is believed to result from increased sulphur capture in coal ash. In this research, experiments with three coals, using size ranges from 90 to 106 urn and 125 to 150 urn, and furnace temperatures of 1300 and 1550 K, demonstrate the extent of sulphur leveraging through increased sulphur retention in ash when cofiring coal and natural gas.
96106357 An examlnatlon of burnlng profiles a8 8 tool to predlct the combustion behavior of coals Pisupati, S. V. Prepr. Pap.-Am. Chem. Sot., Div. Fuel Chem., 1996, 41, (l), 13-18. Burning profiles of a suite of coals ranging from fresh coals to severely weathered coals, and subbituminous coals and bituminous coals were obtained. Combustion efficiences were also determined in a drop tube reactor, 1000 lb/h research boiler, and a 15,000 lb/h industrial-scale demonstration boiler. A good correlation was obtained between the initial temperature and the combustion efficiency obtained under identical conditions. ExperImental analyels of a free fall reactor 96106356 Takahashi, H. et al., Coal Sci. Technol., 1995, 24, 985-988. This study used a free fall reactor to study three Japanese coals: Taiheiyo, Akabira and Miike coals. It was revealed that the free fall reactor enables 24-42 mesh Akabira coal to accumulate THF solubles in the char and melt, which was not seen by TG at 3 K/min for >-lo0 mesh particles. This phenomenon is clearly due to the larger heat and mass tranifer resistances associated with large particle sizes. The fate of chlorine In coal combustion 96106359 Pan, W. P. et al:, Coal Sci. Technol., 1995, 24, 815-818. HCl release profiles indicated that the evolution of chlorine as HCI as broad overlapping peaks between 250 and 600”. The HCl release rate reaches a third maximum at 300 and 400°, which matches closely with the second and the third water release peak. Another small peak around 750”is only observed for higher chlorine content coals. The main chemical forms of chlorine present in coal that have been proposed are inorganic chlorine and chlorine ions in brine and other water associated with the coal.
Fuel and Energy Abstract8
November
1996
447