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05299 The release of nitrogen during the combustion of coal chars: The role of volatile matter and surface area
09
Raman-LIF measurements of temperature, 96105295 species, OH, and NO In a methane-air bunsen flame
major
Nguyen, Q. V. et al., Combwion & Fkmw, Jun. 1996, 105, (4). 499-510. Nonintrusive measurements of temperature, the major species (Nz, 0,, Hz, H,O, CO,, CO, CH,) OH, and NO in an atmospheric pressure, laminar methane-air Bunsen flame were obtained using a combination of RamanRayleigh scattering and laser-induced fluorescence. Radial profiles were measured at three axial locations for an equivalence ratio of 1.38. Measurements along the centreline of the flame, for equivalence ratios of 1.38, 1.52, and 1.70, were also obtained.
Reaction-kinetic studies of combustion of coal par96105296 ticles in a high-temperature drop-tube reactor Seewald, H. et al., VDI-Be-r., 1995, 1193, 111-118. (In German) The paper describes how systematic experiments were carried out to study the pyrolysis and combustion kinetic behavrour of coal particles a! 9001500 and varying 0, concentrations in a drop-tube furnace. Converston vs time curves were obtained and evaluated with the help of a comprehensive theoretical model. 96105297 Reduction of SO, emissions by ammonia gas during unstaged combustion Khan, W. Z. and Gibbs, B. M. Environ. Mohir. Assess., 1996, 40, (2), 157-170. Discusses a study of the reduction of SGr by the addition of ammonia gas in a 2 m-high fluidized-bed combustor with a 30-cm static bed height and a freeboard height of 170 cm. 96105296 Relationships between bifurcation and numerical analyses for Ignition of hydrogen-air diffusion flames Sanchez, A. L. er al., Combustion & Flame, Jun. 1996, 105, (4) 569-590. Linear bifurcation and numerical techniques are employed to determine critical conditions for ignition in steady, counterflow, nonpremixed hydrogen-air systems, with varying degrees of nitrogen dilution of the fuel, at temperatures larger than the crossover temperature associated wjith the second explosion limit for hydrogen. Analysis of profiles of the radical pool at ignition reveals that, irrespective of the degree of dilution of the fuel or oxidizer streams, the O-atom steady state fails on the oxidizer side of the mixing layer. Therefore, at least three overall steps, with 0 and H atoms as the chain-branching species, are necessary to describe the ignition process. The release of nitrogen during the combustion of 96105299 coal chars: The role of volatile matter and surface area Lazaro, M. J. er al., Fuel, Jun. 1996, 75, (8), 1014-1024. The effect of pyrolysis conditions on the release of nitrogen during char combustion was investigated. A fluidized bed pyrolysis unit was used to produce several chars at different temperatures and pressures from a Spanish coal. In this way, a number of chars differing in volatile matter and specific surface area were obtained. 96/05300 Response of counterflow premlxed flames to osclllatlng strain rates Im. H. G. ef al., Combustion & Flame, May 1996, 105, (3), 358-372. The authors studied the response of premixed counterflow flames to an imposed oscillating strain rate which has potential application to both turbulent combustion and acoustic instabilities. They exploited the limit of large activation energy to resolve the reaction zone structure, and conducted a linear perturbation analysis of small amplitude of oscillation. Reaction-sheet fluctuations and the net heat release rate are investigated for both the symmetric twin-flame configuration and a single flame residing in a counterflow system consisting of a fresh-mixture stream impinging on a cold inert stream, Shock tube and modellng study of ketene oxldatlon 96105301 Hidaka, Y. et ol., Combustion & Flame, Jul. 1996, 106, (l), 155-167. Ketene oxidation was studied behind reflected shock waves in the temperature range 1050-2050 K at total pressures between 1.1 and 3.0 atm using ketene-OZ and ketene-N,O mixtures diluted with Ar. Ketene decay and carbon droxrde production were followed using time-resolved UV-absorption at 200 nm and time-resolved IR-emission at 4.24 urn, respectively. Production yields for reaction times between 1.7 and 2.1 ms were also studied using a single-pulse method. 96105302 Shock tube experlments on lgnltlon of pulverized coal particles Banin, V. E. et al., Coal Sci. Technol., 1995, 24, (I), 591-594. Solid waste pyrolysis In a pilot-scale batch 96105303 pyrolyser Avenell, C. S. el al., Fuel, Aug. 1996, 75, (lo), 1167-1174. The pyrolysis of different solid wastes was studied with a pilot-scale batch pyrolyser at different temperatures, fuel/air ratios and reaction times. The temperature distributions of the pyrolyser under control conditions and in the pyrolysis runs were determined. The gas and char yields were determined and the evolved gases analysed. The SO, and NO, emissions were low, 8-70 and O-20 ppmv respectively, even m the pyrolysis of highsulphur materials. The main combustible component of the pyrogas was acetylene (5-15 vol.%). Significant levels of methane and carbon monoxide, typically 3-10 and 2-5 vol.% respectively, were also found.
Combustion
(burners, combustion
systems)
Soot suppression by ferrocene In laminar ethy96105304 lene/air nonpremixed flames Zhang, J. and Megaridis. M. Combustiojl & Flume, Jun. 1996, 105, (4), 528-540. An experimental investigation is presented on the origin of the soot sup pressing role of ferrocene additive in laminar, coannular, ethylene/air nonpremixed flames. The conditions examined involve laminar flames operating above and below their smoke point. In-flame diagnostics are employed to discern the interaction between the soot matrix and additive combustion products. The data presented in a previous study, as produced by thermophoretic sampling, transmission electron microscopy and highresolution microanalysis techniques, are supplemented by soot volume fraction, temperature, and soot primary size measurements to unravel the mechanisms through which ferrocene combustion products influence soot formation processes. 96105305 Specific heat capacity and enthalpy of coal pyrolysis at elevated temperatures Tomeczek, J. and Palugniok, H. Fuel, Jul. 1996, 75, (9), 1089-1093. An experimental procedure was developed enabling the specific heat capacity and enthalpy of coal pyrolysis in the instantaneous state at a given temperature to be determined. It was used to measure the thermal groperties of six coals and the mineral matter at temperatures up to 1300 C. The theoretically predicted maximum of the specific heat capacity at approximately 600°C was reproduced experimentally. However, for temperatures >lOO@C the models considerably overpredicted the experimental results. It was also found that between 300 and 800°C the decomposition of coal is endothermic, with the enthalpy of reaction approximately 120kJ kg” parent coal. Above 800°C decomposition of coal can vary from endothermic to exothermic, with the enthalpy up to 2OOkJ kg-’ parent coal.
Statistical
kinetics
for char combustion
and carbon
Hurt, R. H. et al, Coal Sci. Techuol., 1995, 24, (l), 611-614. A statistical kinetic model for char combustion is first developed for a single-particle data, and then used in burnout simulations to assess the heterogeneity hypothesis and provides insight into the origin of unburned carbon.
96105307 Study of catalytic effects of metallic compounds on coal combustion Fan, H. er ol., Rotrshao Kexue YL~Jishu, 1995, 1, (3). 212-218. (In Chinese) The paper discusses the catalytic effects of metallic compounds on coal combustion.
96105306 Study of coal/petroleum coke combustion characterlstlcs In pulverlzed coal fired furnace Zhang, Z. er al., Coal Sci. Technol., 1995, 24, (l), 527-530. Describes how a blend of pulverized coal with petroleum coke was used in pulverized coal fired furnaces. The sulphur content was controlled by blending. The blend was fired in a 220 t/h furnace in China.
96105309 Study of dlstorted PC concentration combustion and Its appllcatlon In a power holler furnace Hui, S. et al., Ranshao Kexue Yu Jishu, 1995, 1, (3) 241-245. (In Chinese) Distorted PC concentration combustion is a new technology, which was developed for increasing the turning-down ratio of a boiler and decreasing the NO, emission in flue gas. According to the characteristic of coal combustion, high PC concentration, temperature and turbulence intensity on the fire-facing side are adopted.
Study of the fast reactlon characterlstlcs of aluml96105310 nlzed PETN exploslve powders Dong, H. and Zhumei, S. Combustion & Flame, May 1996, 105, (3), 428-430. The fast reaction characteristics of aluminized PETN explosive powders have been studied successfully by means of spectrum-detecting and recovery technique. The results show that the appropriate particle size and content of aluminium powder in the aluminized PETN explosive powders are 44 urn and 33%, respectively.
Study on lgnltlon of large carbon/char particles 96105311 Ge. Y. et al., Ra,lshoo Kexue Yu Jishu, 1995. 1, (2). 162-167. (In Chinese) The paper discusses the ignition process of a large carbon/char particle. Based on the experiments and numerical calculation, the different behaviour between the large and small carbon/char particle ignition is found, and there exists no sudden jump point of the temperature history of a large particle, so the ignition condition, dZTidtz = 0, can not be used. According to different ignition behaviour of a large particle, a new ignition criterion is proposed in this paper.
Fuel and Energy
Abstracts
September
1996
371
Raman-LIF measurements of temperature, 96105295 species, OH, and NO In a methane-air bunsen flame
major
Nguyen, Q. V. et al., Combwion & Fkmw, Jun. 1996, 105, (4). 499-510. Nonintrusive measurements of temperature, the major species (Nz, 0,, Hz, H,O, CO,, CO, CH,) OH, and NO in an atmospheric pressure, laminar methane-air Bunsen flame were obtained using a combination of RamanRayleigh scattering and laser-induced fluorescence. Radial profiles were measured at three axial locations for an equivalence ratio of 1.38. Measurements along the centreline of the flame, for equivalence ratios of 1.38, 1.52, and 1.70, were also obtained.
Reaction-kinetic studies of combustion of coal par96105296 ticles in a high-temperature drop-tube reactor Seewald, H. et al., VDI-Be-r., 1995, 1193, 111-118. (In German) The paper describes how systematic experiments were carried out to study the pyrolysis and combustion kinetic behavrour of coal particles a! 9001500 and varying 0, concentrations in a drop-tube furnace. Converston vs time curves were obtained and evaluated with the help of a comprehensive theoretical model. 96105297 Reduction of SO, emissions by ammonia gas during unstaged combustion Khan, W. Z. and Gibbs, B. M. Environ. Mohir. Assess., 1996, 40, (2), 157-170. Discusses a study of the reduction of SGr by the addition of ammonia gas in a 2 m-high fluidized-bed combustor with a 30-cm static bed height and a freeboard height of 170 cm. 96105296 Relationships between bifurcation and numerical analyses for Ignition of hydrogen-air diffusion flames Sanchez, A. L. er al., Combustion & Flame, Jun. 1996, 105, (4) 569-590. Linear bifurcation and numerical techniques are employed to determine critical conditions for ignition in steady, counterflow, nonpremixed hydrogen-air systems, with varying degrees of nitrogen dilution of the fuel, at temperatures larger than the crossover temperature associated wjith the second explosion limit for hydrogen. Analysis of profiles of the radical pool at ignition reveals that, irrespective of the degree of dilution of the fuel or oxidizer streams, the O-atom steady state fails on the oxidizer side of the mixing layer. Therefore, at least three overall steps, with 0 and H atoms as the chain-branching species, are necessary to describe the ignition process. The release of nitrogen during the combustion of 96105299 coal chars: The role of volatile matter and surface area Lazaro, M. J. er al., Fuel, Jun. 1996, 75, (8), 1014-1024. The effect of pyrolysis conditions on the release of nitrogen during char combustion was investigated. A fluidized bed pyrolysis unit was used to produce several chars at different temperatures and pressures from a Spanish coal. In this way, a number of chars differing in volatile matter and specific surface area were obtained. 96/05300 Response of counterflow premlxed flames to osclllatlng strain rates Im. H. G. ef al., Combustion & Flame, May 1996, 105, (3), 358-372. The authors studied the response of premixed counterflow flames to an imposed oscillating strain rate which has potential application to both turbulent combustion and acoustic instabilities. They exploited the limit of large activation energy to resolve the reaction zone structure, and conducted a linear perturbation analysis of small amplitude of oscillation. Reaction-sheet fluctuations and the net heat release rate are investigated for both the symmetric twin-flame configuration and a single flame residing in a counterflow system consisting of a fresh-mixture stream impinging on a cold inert stream, Shock tube and modellng study of ketene oxldatlon 96105301 Hidaka, Y. et ol., Combustion & Flame, Jul. 1996, 106, (l), 155-167. Ketene oxidation was studied behind reflected shock waves in the temperature range 1050-2050 K at total pressures between 1.1 and 3.0 atm using ketene-OZ and ketene-N,O mixtures diluted with Ar. Ketene decay and carbon droxrde production were followed using time-resolved UV-absorption at 200 nm and time-resolved IR-emission at 4.24 urn, respectively. Production yields for reaction times between 1.7 and 2.1 ms were also studied using a single-pulse method. 96105302 Shock tube experlments on lgnltlon of pulverized coal particles Banin, V. E. et al., Coal Sci. Technol., 1995, 24, (I), 591-594. Solid waste pyrolysis In a pilot-scale batch 96105303 pyrolyser Avenell, C. S. el al., Fuel, Aug. 1996, 75, (lo), 1167-1174. The pyrolysis of different solid wastes was studied with a pilot-scale batch pyrolyser at different temperatures, fuel/air ratios and reaction times. The temperature distributions of the pyrolyser under control conditions and in the pyrolysis runs were determined. The gas and char yields were determined and the evolved gases analysed. The SO, and NO, emissions were low, 8-70 and O-20 ppmv respectively, even m the pyrolysis of highsulphur materials. The main combustible component of the pyrogas was acetylene (5-15 vol.%). Significant levels of methane and carbon monoxide, typically 3-10 and 2-5 vol.% respectively, were also found.
Combustion
(burners, combustion
systems)
Soot suppression by ferrocene In laminar ethy96105304 lene/air nonpremixed flames Zhang, J. and Megaridis. M. Combustiojl & Flume, Jun. 1996, 105, (4), 528-540. An experimental investigation is presented on the origin of the soot sup pressing role of ferrocene additive in laminar, coannular, ethylene/air nonpremixed flames. The conditions examined involve laminar flames operating above and below their smoke point. In-flame diagnostics are employed to discern the interaction between the soot matrix and additive combustion products. The data presented in a previous study, as produced by thermophoretic sampling, transmission electron microscopy and highresolution microanalysis techniques, are supplemented by soot volume fraction, temperature, and soot primary size measurements to unravel the mechanisms through which ferrocene combustion products influence soot formation processes. 96105305 Specific heat capacity and enthalpy of coal pyrolysis at elevated temperatures Tomeczek, J. and Palugniok, H. Fuel, Jul. 1996, 75, (9), 1089-1093. An experimental procedure was developed enabling the specific heat capacity and enthalpy of coal pyrolysis in the instantaneous state at a given temperature to be determined. It was used to measure the thermal groperties of six coals and the mineral matter at temperatures up to 1300 C. The theoretically predicted maximum of the specific heat capacity at approximately 600°C was reproduced experimentally. However, for temperatures >lOO@C the models considerably overpredicted the experimental results. It was also found that between 300 and 800°C the decomposition of coal is endothermic, with the enthalpy of reaction approximately 120kJ kg” parent coal. Above 800°C decomposition of coal can vary from endothermic to exothermic, with the enthalpy up to 2OOkJ kg-’ parent coal.
Statistical
kinetics
for char combustion
and carbon
Hurt, R. H. et al, Coal Sci. Techuol., 1995, 24, (l), 611-614. A statistical kinetic model for char combustion is first developed for a single-particle data, and then used in burnout simulations to assess the heterogeneity hypothesis and provides insight into the origin of unburned carbon.
96105307 Study of catalytic effects of metallic compounds on coal combustion Fan, H. er ol., Rotrshao Kexue YL~Jishu, 1995, 1, (3). 212-218. (In Chinese) The paper discusses the catalytic effects of metallic compounds on coal combustion.
96105306 Study of coal/petroleum coke combustion characterlstlcs In pulverlzed coal fired furnace Zhang, Z. er al., Coal Sci. Technol., 1995, 24, (l), 527-530. Describes how a blend of pulverized coal with petroleum coke was used in pulverized coal fired furnaces. The sulphur content was controlled by blending. The blend was fired in a 220 t/h furnace in China.
96105309 Study of dlstorted PC concentration combustion and Its appllcatlon In a power holler furnace Hui, S. et al., Ranshao Kexue Yu Jishu, 1995, 1, (3) 241-245. (In Chinese) Distorted PC concentration combustion is a new technology, which was developed for increasing the turning-down ratio of a boiler and decreasing the NO, emission in flue gas. According to the characteristic of coal combustion, high PC concentration, temperature and turbulence intensity on the fire-facing side are adopted.
Study of the fast reactlon characterlstlcs of aluml96105310 nlzed PETN exploslve powders Dong, H. and Zhumei, S. Combustion & Flame, May 1996, 105, (3), 428-430. The fast reaction characteristics of aluminized PETN explosive powders have been studied successfully by means of spectrum-detecting and recovery technique. The results show that the appropriate particle size and content of aluminium powder in the aluminized PETN explosive powders are 44 urn and 33%, respectively.
Study on lgnltlon of large carbon/char particles 96105311 Ge. Y. et al., Ra,lshoo Kexue Yu Jishu, 1995. 1, (2). 162-167. (In Chinese) The paper discusses the ignition process of a large carbon/char particle. Based on the experiments and numerical calculation, the different behaviour between the large and small carbon/char particle ignition is found, and there exists no sudden jump point of the temperature history of a large particle, so the ignition condition, dZTidtz = 0, can not be used. According to different ignition behaviour of a large particle, a new ignition criterion is proposed in this paper.
Fuel and Energy
Abstracts
September
1996
371