Nazeer, WA
1999
Detailed Measurements in a Pulverized Coal Flame with Reburning
Nazeer, W.A.; Jackson, R.E.; Peart, J.A. and Tree, D.R.
Fuel, 78:689-699, 1999.
Gas composition and temperature profiles have been measured inside a 200 kW, entrained flow, pulverized coal, Controlled Profile Reactor (CPR) using reburning for NO reduction. NO, CO, NOx, O2, and samples were collected with a water-cooled and water-quenched stainless steel probe and analyzed on a dry basis with on-line gas analyzers and an ion-sensitive electrode (NH3) over a grid of 36 locations within the reactor. Temperature data were obtained with a suction pyrometer using a S-type shielded thermocouple. NO reduction with reburning was investigated over a range of residence times and reburning zone stoichiometric ratios to optimize for maximum NO reduction in the flue gases. A decrease in stoichiometric ratio of the reburning zone resulted in an increase in NO reduction up to a maximum of 70 % at a stoichiometric ratio of 0.78. Moving the tertiary air injector up and down axially varied the residence time in the reburning zone. Increasing residence time in the reburning zone was initially beneficial but became unimportant when residence time became longer than 700 ms. The location of the reburning zone was found to be optimal when reburning fuel was directed at the location of highest NO concentration (i.e., immediately following NO formation). In comparison to a baseline case without reburning, the rate of carbon burnout was found to be higher with 20 cm of primary fuel injection but proceeded more slowly through the reburning zone. At the end of the reactor, burnout was more complete in the baseline case. The species, temperature, and solid sample elemental concentrations appeared to be self-consistent and should provide accurate data for comparison with modeling results.
In-Situ Species, Temperature, and Velocity Measurements in a Pulverized Coal Flame
Nazeer, W.A.; Pickett, L.M. and Tree, D.R.
Combustion Science and Technology, 143: 63, 1999.
A study of detailed species, velocity and temperature data of a pulverized coal flame is important to understanding the mechanisms that sustain the flame and lead to the formation of various pollutants such as NOx. The data can be particularly useful when compared to comprehensive combustion models that encapsulate the sub-models and processes of combustion. This data set contains in-situ axial and radial temperature, velocity and species concentrations for three swirl ratios of a pulverized coal flame located in a cylindrical, down-fired, 0.2 MWt reactor. Species measurements include CO, CO2, NO, and O2. Velocity measurements were obtained using Laser Doppler Anemometry (LDA) and are summarized here after the method and results were reported in detail in a companion paper. The data show the change in structure of the coal flame as swirl is increased. At zero swirl the flame was located along a centerline jet, but as swirl increased, a recirculation zone was created which carried the combustion products up along the centerline of the reactor. Effluent NO was found to correlate with the recirculation of products into the devolitilization zone and with the evidence of reduced mixing of fuel and secondary air at the primary tube outlet. Species measurements agreed with LDA results where concentrations of O2 were highest in the region of the secondary air jet. The species and temperature measurements are self-consistent suggesting the data is accurate and will be useful when compared to combustion models.
1997
Species and Temperature Measurements in a Pulverized Coal Controlled Profile Reactor with Natural Gas Reburning
Nazeer, W.
Species and Temperature Measurements in a Pulverized Coal Controlled Profile Reactor with Natural Gas Reburning, M.S./BYU, August 1997. Advisor: Tree
Detailed Species and Temperature Measurements in a Pulverized Coal Flame with Natural Gas Reburning
Nazeer, W.A.; Jackson, R.E. and Tree, D.R.
Presented at the Fall Meeting of the Western States Section/Combustion Institute, SCAQMD Headquarter, Diamond Bar, California, October 23-24, 1997. Funded by US Department of Energy/University Coal Research and ACERC.
Gas composition and temperature profiles have been measured inside a 200 KW, entrained flow, pulverized coal, Controlled Profile Reactor (CPR) using reburning for NOx reduction. Reburning in the CPR was achieved by creating a primary reaction zone, a reburning zone with natural gas injection, and a tertiary zone with additional air injection. The primary reaction zone under oxidizing conditions inhibits the formation of most of the fuel NOx. The natural gas injection in the reburning zone forms fuel radicals under reducing conditions, which react with primary zone NOx to convert it to elemental nitrogen. Air added in the tertiary zone consumes the leftover reburning fuel. The NO, CO, CO2, NOx, O2, HCN and NH3 samples were collected with a water-cooled and water-quenched stainless steel probe and analyzed on a dry basis with online gas analyzers. The temperature data inside the CPR was obtained with a suction pyrometer using a S-type shielded thermocouple. Both the species and temperature data points were obtained at swirl setting of 0, 0.5, and 1.5 to select a baseline condition for the implementation of a natural gas reburning section inside the CPR. The 1.5 swirl condition was chosen as a baseline for the reburning experiments because it provided and increased residence time for reburning and produced lower primary zone NOx without reburning. This condition also produced peak NOx in an annular region, which appeared to be a good target for the reburning fuel injection. Reburning was studied over a range of residence times and reburning zone equivalence ratios to optimize for maximum NOx reduction in the flue gases. The increase in equivalence ratios of the reburning zone showed an increase in NOx reduction up to a maximum of 68.5% at an equivalence ratio of 1.28. The residence time in the reburning zone was varied by moving the tertiary air injector up and down axially. The increase in residence time in the reburning zone increase NOx reduction to a maximum of 68% when the tertiary air injector was at an axial location of 133 cm from the primary outlet. Further increases in the residence time, accomplished by moving the tertiary air injector to an axial location of 168 cm, did not change the percent of NOx reduction.
Nazeer, WA
1999
Detailed Measurements in a Pulverized Coal Flame with Reburning
Nazeer, W.A.; Jackson, R.E.; Peart, J.A. and Tree, D.R.
Fuel, 78:689-699, 1999.
Gas composition and temperature profiles have been measured inside a 200 kW, entrained flow, pulverized coal, Controlled Profile Reactor (CPR) using reburning for NO reduction. NO, CO, NOx, O2, and samples were collected with a water-cooled and water-quenched stainless steel probe and analyzed on a dry basis with on-line gas analyzers and an ion-sensitive electrode (NH3) over a grid of 36 locations within the reactor. Temperature data were obtained with a suction pyrometer using a S-type shielded thermocouple. NO reduction with reburning was investigated over a range of residence times and reburning zone stoichiometric ratios to optimize for maximum NO reduction in the flue gases. A decrease in stoichiometric ratio of the reburning zone resulted in an increase in NO reduction up to a maximum of 70 % at a stoichiometric ratio of 0.78. Moving the tertiary air injector up and down axially varied the residence time in the reburning zone. Increasing residence time in the reburning zone was initially beneficial but became unimportant when residence time became longer than 700 ms. The location of the reburning zone was found to be optimal when reburning fuel was directed at the location of highest NO concentration (i.e., immediately following NO formation). In comparison to a baseline case without reburning, the rate of carbon burnout was found to be higher with 20 cm of primary fuel injection but proceeded more slowly through the reburning zone. At the end of the reactor, burnout was more complete in the baseline case. The species, temperature, and solid sample elemental concentrations appeared to be self-consistent and should provide accurate data for comparison with modeling results.
In-Situ Species, Temperature, and Velocity Measurements in a Pulverized Coal Flame
Nazeer, W.A.; Pickett, L.M. and Tree, D.R.
Combustion Science and Technology, 143: 63, 1999.
A study of detailed species, velocity and temperature data of a pulverized coal flame is important to understanding the mechanisms that sustain the flame and lead to the formation of various pollutants such as NOx. The data can be particularly useful when compared to comprehensive combustion models that encapsulate the sub-models and processes of combustion. This data set contains in-situ axial and radial temperature, velocity and species concentrations for three swirl ratios of a pulverized coal flame located in a cylindrical, down-fired, 0.2 MWt reactor. Species measurements include CO, CO2, NO, and O2. Velocity measurements were obtained using Laser Doppler Anemometry (LDA) and are summarized here after the method and results were reported in detail in a companion paper. The data show the change in structure of the coal flame as swirl is increased. At zero swirl the flame was located along a centerline jet, but as swirl increased, a recirculation zone was created which carried the combustion products up along the centerline of the reactor. Effluent NO was found to correlate with the recirculation of products into the devolitilization zone and with the evidence of reduced mixing of fuel and secondary air at the primary tube outlet. Species measurements agreed with LDA results where concentrations of O2 were highest in the region of the secondary air jet. The species and temperature measurements are self-consistent suggesting the data is accurate and will be useful when compared to combustion models.
1997
Species and Temperature Measurements in a Pulverized Coal Controlled Profile Reactor with Natural Gas Reburning
Nazeer, W.
Species and Temperature Measurements in a Pulverized Coal Controlled Profile Reactor with Natural Gas Reburning, M.S./BYU, August 1997. Advisor: Tree
Detailed Species and Temperature Measurements in a Pulverized Coal Flame with Natural Gas Reburning
Nazeer, W.A.; Jackson, R.E. and Tree, D.R.
Presented at the Fall Meeting of the Western States Section/Combustion Institute, SCAQMD Headquarter, Diamond Bar, California, October 23-24, 1997. Funded by US Department of Energy/University Coal Research and ACERC.
Gas composition and temperature profiles have been measured inside a 200 KW, entrained flow, pulverized coal, Controlled Profile Reactor (CPR) using reburning for NOx reduction. Reburning in the CPR was achieved by creating a primary reaction zone, a reburning zone with natural gas injection, and a tertiary zone with additional air injection. The primary reaction zone under oxidizing conditions inhibits the formation of most of the fuel NOx. The natural gas injection in the reburning zone forms fuel radicals under reducing conditions, which react with primary zone NOx to convert it to elemental nitrogen. Air added in the tertiary zone consumes the leftover reburning fuel. The NO, CO, CO2, NOx, O2, HCN and NH3 samples were collected with a water-cooled and water-quenched stainless steel probe and analyzed on a dry basis with online gas analyzers. The temperature data inside the CPR was obtained with a suction pyrometer using a S-type shielded thermocouple. Both the species and temperature data points were obtained at swirl setting of 0, 0.5, and 1.5 to select a baseline condition for the implementation of a natural gas reburning section inside the CPR. The 1.5 swirl condition was chosen as a baseline for the reburning experiments because it provided and increased residence time for reburning and produced lower primary zone NOx without reburning. This condition also produced peak NOx in an annular region, which appeared to be a good target for the reburning fuel injection. Reburning was studied over a range of residence times and reburning zone equivalence ratios to optimize for maximum NOx reduction in the flue gases. The increase in equivalence ratios of the reburning zone showed an increase in NOx reduction up to a maximum of 68.5% at an equivalence ratio of 1.28. The residence time in the reburning zone was varied by moving the tertiary air injector up and down axially. The increase in residence time in the reburning zone increase NOx reduction to a maximum of 68% when the tertiary air injector was at an axial location of 133 cm from the primary outlet. Further increases in the residence time, accomplished by moving the tertiary air injector to an axial location of 168 cm, did not change the percent of NOx reduction.