Nichols, KM
1990
Reduction of Fuel-NO by Increased Operating Pressure in a Laboratory-Scale Coal Gasifier
Nichols, K.M.; Hedman, P.O. and Blackham, A.U.
Fuel, 69, 1339-1344, 1990. Funded by US Department of Energy and Morgantown Energy Technology Center.
Measurements of NO during laboratory-scale gasification of a Utah bituminous coal verified that small increases in pressure (from 1 to 2 atm) at constant residence time resulted in dramatic decreases in effluent NO levels. Tests were conducted at 3 target levels of pressure (1, 2 and 4 atm) and 2 target levels of residence time (450 and 900 ms). Oxygen-to-coal ratio for all tests was 0.90 (stoichiometric ration SR=0.45). The dominant factor in causing lower effluent NO levels was the increased kinetic rate of NO decay. Increased residence time in the fuel-rich gasifier contributed to lower effluent NO levels, but was of minor importance when compared to the effect of pressure on the decay rate. Concentrations of N2 appeared to be slightly increased and concentrations of total fuel nitrogen (TFN) decreased as pressure was increased. Also, concentrations of N2 increased and concentrations TFN decreased as residence time was increased at 1 atm pressure. For all tests, nitrogen conversion exceeded carbon conversion by about 10%. Neither nitrogen conversion nor carbon conversion was found to increase with increasing pressure. Both increased slightly (4-5%) with increasing residence time, evidence that most of the coal nitrogen and carbon was released during devolatilization.
1989
Reduction of Fuel NO by Increased Operating Pressure in a Laboratory-Scale Coal Gasifier
Nichols, K.M.; Hedman, P.O. and Blackham, A.U.
1989 Joint Environmental Protection Agency/Electric Power Research Institute Symposium on Stationary Combustion NOx Control, San Francisco, California, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates).
Measurements of NO during laboratory-scale gasification of a Utah bituminous coal verified that small increases in pressure (from 1 to 2 atm) at constant residence time resulted in dramatic decreases in effluent NO levels. Tests were conducted at 3 target levels of pressure (1, 2, and 4 atm) and 2 target levels of residence time (450 and 900 ms). Oxygen-to-coal ratio for all tests was 0.90 (SR = 0.45). The dominant factor in causing lower effluent NO levels was the increased kinetic rate of NO decay. Increased residence time in the fuel-rich gasifier contributed to lower effluent NO levels, but was of minor importance when compared to the effect of pressure on the decay rate. Concentrations of N2 appeared to be slightly increased and concentrations of TFN decreased as pressure was increased. Neither TFN or N2 concentrations were affected by increasing residence time. For all tests, nitrogen conversion exceeded carbon conversion by about 10%. Neither nitrogen conversion nor carbon conversion was found to increase with increasing pressure. Both increased slightly (4-5%) with increasing residence time, evidence that most of the coal nitrogen and carbon was released during devolatilization.
1988-1986
Release and Reaction of Fuel-Nitrogen in a High-Pressure Entrained-Coal Gasifier
Nichols, K.M.; Hedman, P.O. and Smoot, L.D.
Fuel, 66, 1257-1263, 1987. 7 pgs. Funded by Morgantown Energy Technology Center.
Effects of pressure, flame type and coal feed rate on fuel-nitrogen release and nitrogen pollutant formation were examined in a laboratory scale, entrained-coal gasifier. A Utah, high-volatile bituminous coal was used. With a water-quenched probe, gas-particulate samples were collected for oxygen-coal mass ratios from 0.6 to 1.1, pressures of 1, 4.9 and 10.4 atm and coal feed rates of 25 and 35 kg·h-1. Two injector types were utilized; one produced a diffusion flame, the other a premixed flame. Fuel-nitrogen release from the coal showed little dependence on oxygen-coal ratio, pressure or coal feed rate. Values at the gasifier exit averaged 83% for the diffusion flame and 92% for the premixed flame.
Fuel-nitrogen release, mostly during devolatilization, exceeded fuel-carbon release by . 10% for the premixed flame and . 30% for the diffusion flame, depending on oxygen-coal mass ratio. Over 50% of the released fuel-nitrogen formed N2, with significant amounts of NH3 and HCN, and smaller amounts of NO. Increased pressure at constant mass feed rates caused sharp decreases in effluent NO concentrations (to near zero) for both flame types which was explained by a combination of increased residence time and increased homogeneous NO decay rate. Elevated pressure also increased the effluent NH3 and decreased HCN concentrations for the diffusion flame whereas the more complete mixing of the premixed flame resulted in lower NH3 and HCN levels, and higher N2 levels. In general, nitrogen species concentrations were not largely affected by coal feed rate, though increased coal feed rate decreased NH3 levels somewhat. From these observations, together with observations from other investigators; possible explanations are postulated.
Sulfur Species Formation in a High-pressure Entrained-Coal Gasifier
Nichols, K.M.; Hedman, P.O.; Smoot, L.D. and Blackham, A.U.
Western States Section, 1987, The Combustion Institute, Provo, UT. 16 pgs. Funded by Morgantown Energy Technology Center.
This work summarizes several observations concerning the effects of pressure and oxygen-to-coal mass ratio on the fate of coal-sulfur during entrained gasification. A high-volatile bituminous coal was pulverized to a mass mean of near 50 mm. The coal was gasified with oxygen in a laboratory-scale entrained-flow gasifier. Test pressures were atmospheric (1.0 ATM, 101 kPa), 4.9 ATM (500 kPa), and 10.4 ATM (1050 kPa). Oxygen-to-coal mass ratios between 0.6 and 1.1 were investigated. Gas-particulate samples were collected with a water-quenched probe from the gasifier chamber effluent stream. Measurements were made of the sulfur retained in the char particles and of the concentrations of H2S, SO2, COS and CS2 in the product gas. Conversion of sulfur to the gas phase was observed to decrease with increasing pressure, possibly through sulfur captured by char. Changing pressure caused a change in the distribution of gas phase sulfur species. At higher pressure, the proportions of SO2 and CS2 decreased, and the proportion of H2S increased. This redistribution with increasing pressure is not predicted by equilibrium calculations, nor was it observed in learner (less particle laden) combustion environments. This suggests the importance of char in determining the fate of the coal-sulfur during gasification. Increasing oxygen-to-coal mass ratio increased sulfur conversion, SO2 concentration, and COs concentration, while it decreased H2S and CS2 concentrations.
Release and Reaction of Fuel-Nitrogen in a High-pressure Entrained-Coal Gasifier
Nichols, K.M.; Hedman, P.O. and Smoot, L.D.
Western States Section, 1986, The Combustion Institute, Tucson, AZ. Also published in Fuel, 1257-1263, 1987. 7 pgs. Funded by US Department of Energy and Morgantown Energy Technology Center.
Effects of pressure, flame type and coal feed rate on fuel-nitrogen release and nitrogen pollutant formation were examined in a laboratory scale, entrained-coal gasifier. A Utah, high-volatile bituminous coal was used. With a water-quenched probe, gas-particulate samples were collected for oxygen-coal mass ratios from 0.6 to 1.1, pressures of 1, 4.9 and 10.4 ATM and coal feed rates of 25 and 35 kg·h-1. Two injector types were utilized; one produced a diffusion flame, the other a premixed flame. Fuel-nitrogen release from the coal showed little dependence on oxygen-coal ratio, pressure or coal feed rate. Values at the gasifier exit averaged 83% for the diffusion flame and 92% for the premixed flame. Fuel-nitrogen release, mostly during devolatilization, exceeded fuel-carbon released by ~10% for the premixed flame and ~30% for the diffusion flame, depending on oxygen-coal mass ratio. Over 50% of the released fuel-nitrogen formed N2, with significant amounts of NH3 and HCN, and smaller amounts of NO. Increased pressure at constant mass feed rates caused sharp decreases in effluent NO concentrations (to near zero) for both flame types which was explained by a combination of increased residence time and increased homogeneous NO decay rate. Elevated pressure also increased the effluent NH3 and decreased HCN concentrations for the diffusion flame whereas the more complete mixing of the premixed flame resulted in lower NH3 and HCN levels, and higher N2 levels. In general, nitrogen species concentrations were not largely affected by coal feed rate, though increased coal feed rate decreased NH3 levels somewhat.
Nichols, KM
1990
Reduction of Fuel-NO by Increased Operating Pressure in a Laboratory-Scale Coal Gasifier
Nichols, K.M.; Hedman, P.O. and Blackham, A.U.
Fuel, 69, 1339-1344, 1990. Funded by US Department of Energy and Morgantown Energy Technology Center.
Measurements of NO during laboratory-scale gasification of a Utah bituminous coal verified that small increases in pressure (from 1 to 2 atm) at constant residence time resulted in dramatic decreases in effluent NO levels. Tests were conducted at 3 target levels of pressure (1, 2 and 4 atm) and 2 target levels of residence time (450 and 900 ms). Oxygen-to-coal ratio for all tests was 0.90 (stoichiometric ration SR=0.45). The dominant factor in causing lower effluent NO levels was the increased kinetic rate of NO decay. Increased residence time in the fuel-rich gasifier contributed to lower effluent NO levels, but was of minor importance when compared to the effect of pressure on the decay rate. Concentrations of N2 appeared to be slightly increased and concentrations of total fuel nitrogen (TFN) decreased as pressure was increased. Also, concentrations of N2 increased and concentrations TFN decreased as residence time was increased at 1 atm pressure. For all tests, nitrogen conversion exceeded carbon conversion by about 10%. Neither nitrogen conversion nor carbon conversion was found to increase with increasing pressure. Both increased slightly (4-5%) with increasing residence time, evidence that most of the coal nitrogen and carbon was released during devolatilization.
1989
Reduction of Fuel NO by Increased Operating Pressure in a Laboratory-Scale Coal Gasifier
Nichols, K.M.; Hedman, P.O. and Blackham, A.U.
1989 Joint Environmental Protection Agency/Electric Power Research Institute Symposium on Stationary Combustion NOx Control, San Francisco, California, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates).
Measurements of NO during laboratory-scale gasification of a Utah bituminous coal verified that small increases in pressure (from 1 to 2 atm) at constant residence time resulted in dramatic decreases in effluent NO levels. Tests were conducted at 3 target levels of pressure (1, 2, and 4 atm) and 2 target levels of residence time (450 and 900 ms). Oxygen-to-coal ratio for all tests was 0.90 (SR = 0.45). The dominant factor in causing lower effluent NO levels was the increased kinetic rate of NO decay. Increased residence time in the fuel-rich gasifier contributed to lower effluent NO levels, but was of minor importance when compared to the effect of pressure on the decay rate. Concentrations of N2 appeared to be slightly increased and concentrations of TFN decreased as pressure was increased. Neither TFN or N2 concentrations were affected by increasing residence time. For all tests, nitrogen conversion exceeded carbon conversion by about 10%. Neither nitrogen conversion nor carbon conversion was found to increase with increasing pressure. Both increased slightly (4-5%) with increasing residence time, evidence that most of the coal nitrogen and carbon was released during devolatilization.
1988-1986
Release and Reaction of Fuel-Nitrogen in a High-Pressure Entrained-Coal Gasifier
Nichols, K.M.; Hedman, P.O. and Smoot, L.D.
Fuel, 66, 1257-1263, 1987. 7 pgs. Funded by Morgantown Energy Technology Center.
Effects of pressure, flame type and coal feed rate on fuel-nitrogen release and nitrogen pollutant formation were examined in a laboratory scale, entrained-coal gasifier. A Utah, high-volatile bituminous coal was used. With a water-quenched probe, gas-particulate samples were collected for oxygen-coal mass ratios from 0.6 to 1.1, pressures of 1, 4.9 and 10.4 atm and coal feed rates of 25 and 35 kg·h-1. Two injector types were utilized; one produced a diffusion flame, the other a premixed flame. Fuel-nitrogen release from the coal showed little dependence on oxygen-coal ratio, pressure or coal feed rate. Values at the gasifier exit averaged 83% for the diffusion flame and 92% for the premixed flame.
Fuel-nitrogen release, mostly during devolatilization, exceeded fuel-carbon release by . 10% for the premixed flame and . 30% for the diffusion flame, depending on oxygen-coal mass ratio. Over 50% of the released fuel-nitrogen formed N2, with significant amounts of NH3 and HCN, and smaller amounts of NO. Increased pressure at constant mass feed rates caused sharp decreases in effluent NO concentrations (to near zero) for both flame types which was explained by a combination of increased residence time and increased homogeneous NO decay rate. Elevated pressure also increased the effluent NH3 and decreased HCN concentrations for the diffusion flame whereas the more complete mixing of the premixed flame resulted in lower NH3 and HCN levels, and higher N2 levels. In general, nitrogen species concentrations were not largely affected by coal feed rate, though increased coal feed rate decreased NH3 levels somewhat. From these observations, together with observations from other investigators; possible explanations are postulated.
Sulfur Species Formation in a High-pressure Entrained-Coal Gasifier
Nichols, K.M.; Hedman, P.O.; Smoot, L.D. and Blackham, A.U.
Western States Section, 1987, The Combustion Institute, Provo, UT. 16 pgs. Funded by Morgantown Energy Technology Center.
This work summarizes several observations concerning the effects of pressure and oxygen-to-coal mass ratio on the fate of coal-sulfur during entrained gasification. A high-volatile bituminous coal was pulverized to a mass mean of near 50 mm. The coal was gasified with oxygen in a laboratory-scale entrained-flow gasifier. Test pressures were atmospheric (1.0 ATM, 101 kPa), 4.9 ATM (500 kPa), and 10.4 ATM (1050 kPa). Oxygen-to-coal mass ratios between 0.6 and 1.1 were investigated. Gas-particulate samples were collected with a water-quenched probe from the gasifier chamber effluent stream. Measurements were made of the sulfur retained in the char particles and of the concentrations of H2S, SO2, COS and CS2 in the product gas. Conversion of sulfur to the gas phase was observed to decrease with increasing pressure, possibly through sulfur captured by char. Changing pressure caused a change in the distribution of gas phase sulfur species. At higher pressure, the proportions of SO2 and CS2 decreased, and the proportion of H2S increased. This redistribution with increasing pressure is not predicted by equilibrium calculations, nor was it observed in learner (less particle laden) combustion environments. This suggests the importance of char in determining the fate of the coal-sulfur during gasification. Increasing oxygen-to-coal mass ratio increased sulfur conversion, SO2 concentration, and COs concentration, while it decreased H2S and CS2 concentrations.
Release and Reaction of Fuel-Nitrogen in a High-pressure Entrained-Coal Gasifier
Nichols, K.M.; Hedman, P.O. and Smoot, L.D.
Western States Section, 1986, The Combustion Institute, Tucson, AZ. Also published in Fuel, 1257-1263, 1987. 7 pgs. Funded by US Department of Energy and Morgantown Energy Technology Center.
Effects of pressure, flame type and coal feed rate on fuel-nitrogen release and nitrogen pollutant formation were examined in a laboratory scale, entrained-coal gasifier. A Utah, high-volatile bituminous coal was used. With a water-quenched probe, gas-particulate samples were collected for oxygen-coal mass ratios from 0.6 to 1.1, pressures of 1, 4.9 and 10.4 ATM and coal feed rates of 25 and 35 kg·h-1. Two injector types were utilized; one produced a diffusion flame, the other a premixed flame. Fuel-nitrogen release from the coal showed little dependence on oxygen-coal ratio, pressure or coal feed rate. Values at the gasifier exit averaged 83% for the diffusion flame and 92% for the premixed flame. Fuel-nitrogen release, mostly during devolatilization, exceeded fuel-carbon released by ~10% for the premixed flame and ~30% for the diffusion flame, depending on oxygen-coal mass ratio. Over 50% of the released fuel-nitrogen formed N2, with significant amounts of NH3 and HCN, and smaller amounts of NO. Increased pressure at constant mass feed rates caused sharp decreases in effluent NO concentrations (to near zero) for both flame types which was explained by a combination of increased residence time and increased homogeneous NO decay rate. Elevated pressure also increased the effluent NH3 and decreased HCN concentrations for the diffusion flame whereas the more complete mixing of the premixed flame resulted in lower NH3 and HCN levels, and higher N2 levels. In general, nitrogen species concentrations were not largely affected by coal feed rate, though increased coal feed rate decreased NH3 levels somewhat.