Brown, BW
1988-1986
Measurement and Prediction of Entrained-Flow Gasification Processes
Brown, B.W.; Smoot, L.D.; Smith, P.J. and Hedman, P.O.
AIChE Journal, 34, 3, 435-446, 1988. 12 pgs. Funding source by Morgantown Energy Technology Center.
A detailed mathematical model is used to predict local and effluent properties within an axisymmetric, entrained-flow gasifier. Laboratory experiments were conducted to provide local properties for four coal types from a gasifier operating at near-atmospheric pressure. Effects of selected model parameters and test variables were examined and compared with measurements in most cases. The comparison of predictions and measurements provides the first evaluation of capabilities and limitations of a comprehensive model for entrained-flow gasifiers.
Effect of Coal Type of Entrained Gasification
Brown, B.W.; Smoot, L.D. and Hedman, P.O.
Fuel, 65, 673-678, 1986. 6 pgs. Funded by Morgantown Energy Technology Center.
The effect of coal type for four coals of varying rank was studied in an entrained flow gasifier at atmospheric pressure. The reactor was modified to increase residence time and gas temperature and to provide for direct measurement of the exit gas flow rate. Space-resolved samples were collected from within the gasifier with a water-quenched probe. Correlation of results shows that the most important factors on carbon conversion are O2/coal ratio, coal particle size, coal heating value, missing of reactant feed streams, and coal char reactivity. Premixing of stream with coal and oxygen produced higher levels of hydrogen, but a lower CO/CO2 ratio. Elimination of stream increased the reaction temperature and raised the carbon conversion.
Controlling Mechanisms in Gasification of Pulverized Coal
Smoot, L.D. and Brown, B.W.
Fuel, 66, 1249-1256, 1987. 8 pgs. Funded by Morgantown Energy Technology Center.
Controlling mechanisms in the fuel-rich reaction of pulverized coal with oxygen at atmospheric pressure were investigated through analysis of experimental data and by comparison with predictions of a comprehensive model. Gasification data were obtained for four coal types at various oxygen-steam-coal ratios and effects of coal feed rate, particle size and flame type (premixed, diffusion) were also determined. The results show that coal particle heat-up and devolatilization occur very rapidly (<60-80 ms) near the coal inlet with up to 70% of the coal consumed. Coal volatiles and oxygen are rapidly consumed through gas-phase reaction, producing high gas temperature and high CO2 concentrations. Addition of steam plays little role in the coal reaction process, while residual char (typically containing 20-30% of the carbon) is consumed less rapidly (>200 ms) through surface reaction with CO2 and H2O, and possibly O2 at the onset. This general reaction process varies little among the coal types examined. The surface reactions are controlled in high-temperature regions through oxidizer diffusion to the char surface; however, as the gasifier temperature declines through heat loss and endothermic reaction, heterogeneous char-oxidizer reaction near the particle external surface become more important, giving rise to some dependence on coal type.
Brown, BW
1988-1986
Measurement and Prediction of Entrained-Flow Gasification Processes
Brown, B.W.; Smoot, L.D.; Smith, P.J. and Hedman, P.O.
AIChE Journal, 34, 3, 435-446, 1988. 12 pgs. Funding source by Morgantown Energy Technology Center.
A detailed mathematical model is used to predict local and effluent properties within an axisymmetric, entrained-flow gasifier. Laboratory experiments were conducted to provide local properties for four coal types from a gasifier operating at near-atmospheric pressure. Effects of selected model parameters and test variables were examined and compared with measurements in most cases. The comparison of predictions and measurements provides the first evaluation of capabilities and limitations of a comprehensive model for entrained-flow gasifiers.
Effect of Coal Type of Entrained Gasification
Brown, B.W.; Smoot, L.D. and Hedman, P.O.
Fuel, 65, 673-678, 1986. 6 pgs. Funded by Morgantown Energy Technology Center.
The effect of coal type for four coals of varying rank was studied in an entrained flow gasifier at atmospheric pressure. The reactor was modified to increase residence time and gas temperature and to provide for direct measurement of the exit gas flow rate. Space-resolved samples were collected from within the gasifier with a water-quenched probe. Correlation of results shows that the most important factors on carbon conversion are O2/coal ratio, coal particle size, coal heating value, missing of reactant feed streams, and coal char reactivity. Premixing of stream with coal and oxygen produced higher levels of hydrogen, but a lower CO/CO2 ratio. Elimination of stream increased the reaction temperature and raised the carbon conversion.
Controlling Mechanisms in Gasification of Pulverized Coal
Smoot, L.D. and Brown, B.W.
Fuel, 66, 1249-1256, 1987. 8 pgs. Funded by Morgantown Energy Technology Center.
Controlling mechanisms in the fuel-rich reaction of pulverized coal with oxygen at atmospheric pressure were investigated through analysis of experimental data and by comparison with predictions of a comprehensive model. Gasification data were obtained for four coal types at various oxygen-steam-coal ratios and effects of coal feed rate, particle size and flame type (premixed, diffusion) were also determined. The results show that coal particle heat-up and devolatilization occur very rapidly (<60-80 ms) near the coal inlet with up to 70% of the coal consumed. Coal volatiles and oxygen are rapidly consumed through gas-phase reaction, producing high gas temperature and high CO2 concentrations. Addition of steam plays little role in the coal reaction process, while residual char (typically containing 20-30% of the carbon) is consumed less rapidly (>200 ms) through surface reaction with CO2 and H2O, and possibly O2 at the onset. This general reaction process varies little among the coal types examined. The surface reactions are controlled in high-temperature regions through oxidizer diffusion to the char surface; however, as the gasifier temperature declines through heat loss and endothermic reaction, heterogeneous char-oxidizer reaction near the particle external surface become more important, giving rise to some dependence on coal type.