Pickett, LM
1999
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.
LDA Measurements in a Pulverized Coal Flame at Three Swirl Ratios
Pickett, L.M.; Jackson, R.E. and Tree, D.R.
Combustion Science and Technology, 143:79, 1999.
A two-color Laser Doppler Anemometer (LDA) was used to obtain axial and tangential velocity information in a 0.2 MW pulverized coal flame. In addition to the reacting flow data, a study on the accuracy of using coal as a seed particle to measure gas phase velocity using LDA was performed. Non-reacting flow velocity measurements were also obtained near the fuel inlet and in the quarl region of a geometrically identical burner to assist in establishing modeling inlet conditions. Both the reacting and non-reacting velocity data were obtained at three or more swirl settings and various axial positions allowing a study of the affect of swirl on inlet turbulence and flame structure. The velocity results were compared with effluent NOx measurements. At the flow rates and accelerations experienced in this study, the coal particles were shown to be useful as seed particles for LDA gas phase velocity measurements. The coal-flame velocity indicated a centerline flame at 0 swirl transitioning to a radially directed flame with a central recirculation zone at swirl setting of 0.5 and 1.5. The transition of the flame structure to a central recirculation zone was also seen at the fuel inlet plane in the non-reacting flow studies and was found to correlate with a decrease in measured effluent NOx. Measured axial velocity profiles 5 mm below the fuel inlet showed negative axial velocities (in the opposite direction of the average flow velocity) were produced along the primary tube as swirl was increased from 0 to 1.5 with the transition occurring between 0.5 and 0.75 swirl. Transition in the flow near the fuel inlet correlated well with a drop in effluent NOx and with transitions in the recirculation zones measured further downstream. The strong interaction with burner velocity profiles and NOx suggest velocity is an important measured boundary condition for modeling. The velocity data shown here in combination with a companion paper showing temperature and species data should provide important information needed to develop better models of pulverized coal combustion.
1997
Comprehensive Combustion Code Predictions of the Flow Field for Pulverized Coal Combustion
Jackson, R.E.; Pickett, L.M. and Tree, D.R.
Presented at the Spring Meeting of the Western States Section of the Combustion Institute, Sandia National Laboratories, Livermore, California, April 14-15, 1997. Funded by US Department of Energy/University Coal Research and ACERC.
Comprehensive combustion modeling predictions of a large laboratory (0.2 MW axisymmetric, pulverized coal reactor are compared with detailed velocity measurements. The reactor is down-fired and cylindrical with a radius of 75 cm and an axial length of 2.4 m. Three challenging areas for modeling are investigated, namely grid independence, inflow boundary conditions, and turbulence. The predictions are compared with LDA data obtained at radial profiles in the quarl and at various axial locations throughout the reactor. These velocity maps for the reactor were obtained at three swirl settings at an equivalence ratio of 0.9. Two readily available combustion CFD codes were used, FLUENT and PCGC-3. Proper grid resolution is shown to be particularly important in the flame region. Grid independence for the primary glow structures was achieved for the laboratory reactor. The gross characteristics of the CFD solutions are less sensitive to inflow BCs than expected. The standard kappa-epsilon two-equation model was compared to an RNG base kappa-epsilon model and a non-linear kappa-epsilon model.
LDA, Gas Species and Temperature Measurements in a Pulverized Coal Flame
Pickett, L.M.; Jackson, R.E. and Tree, D.R.
Presented at the Spring Meeting of the Western States Section of the Combustion Institute, Sandia National Laboratories, Livermore, California, April 14-15, 1997. Funded by US Department of Energy/University Coal Research and ACERC.
A two-color Laser Doppler Anemometer (LDA) was used to obtain axial and tangential velocity information in a 0.2 MW pulverized coal flame. In addition to the reacting flow data, a study on velocity slop encountered when coal is used as a seed particle for LDA was performed. Detailed velocity measurements at the outlet plane of a geometrically identical burner were obtained for use as boundary conditions. Velocity data of this type is useful in understanding the nature of pulverized coal flames, particularly with regard to NOx formation, and in developing models for pulverized coal combustion. The reacting flow velocity measurements were obtained throughout the near burner region of the reactor for three swirl settings at an overall stoichiometric ratio of 1.1. The coal-flame velocity data was useful in characterizing the flame structure indicating a centerline flame at 0 swirl transitioning to a radially directed flame with a central recirculation zone at swirl settings of 0.5 and 1.5. The transition of the flame structure to a central recirculation zone was also seen at the burner exit plane in the non-reacting flow studies and was found to correlate with a decrease in measured effluent NOx. At the flow rates and accelerations experienced in this study, the coal particles were shown to have minimal velocity slip. The velocity measurements from this study in combination with gas species and temperature measurements to be reported elsewhere combine to make a rare and comprehensive data set suitable for comprehensive coal combustion modeling development.
Pickett, LM
1999
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.
LDA Measurements in a Pulverized Coal Flame at Three Swirl Ratios
Pickett, L.M.; Jackson, R.E. and Tree, D.R.
Combustion Science and Technology, 143:79, 1999.
A two-color Laser Doppler Anemometer (LDA) was used to obtain axial and tangential velocity information in a 0.2 MW pulverized coal flame. In addition to the reacting flow data, a study on the accuracy of using coal as a seed particle to measure gas phase velocity using LDA was performed. Non-reacting flow velocity measurements were also obtained near the fuel inlet and in the quarl region of a geometrically identical burner to assist in establishing modeling inlet conditions. Both the reacting and non-reacting velocity data were obtained at three or more swirl settings and various axial positions allowing a study of the affect of swirl on inlet turbulence and flame structure. The velocity results were compared with effluent NOx measurements. At the flow rates and accelerations experienced in this study, the coal particles were shown to be useful as seed particles for LDA gas phase velocity measurements. The coal-flame velocity indicated a centerline flame at 0 swirl transitioning to a radially directed flame with a central recirculation zone at swirl setting of 0.5 and 1.5. The transition of the flame structure to a central recirculation zone was also seen at the fuel inlet plane in the non-reacting flow studies and was found to correlate with a decrease in measured effluent NOx. Measured axial velocity profiles 5 mm below the fuel inlet showed negative axial velocities (in the opposite direction of the average flow velocity) were produced along the primary tube as swirl was increased from 0 to 1.5 with the transition occurring between 0.5 and 0.75 swirl. Transition in the flow near the fuel inlet correlated well with a drop in effluent NOx and with transitions in the recirculation zones measured further downstream. The strong interaction with burner velocity profiles and NOx suggest velocity is an important measured boundary condition for modeling. The velocity data shown here in combination with a companion paper showing temperature and species data should provide important information needed to develop better models of pulverized coal combustion.
1997
Comprehensive Combustion Code Predictions of the Flow Field for Pulverized Coal Combustion
Jackson, R.E.; Pickett, L.M. and Tree, D.R.
Presented at the Spring Meeting of the Western States Section of the Combustion Institute, Sandia National Laboratories, Livermore, California, April 14-15, 1997. Funded by US Department of Energy/University Coal Research and ACERC.
Comprehensive combustion modeling predictions of a large laboratory (0.2 MW axisymmetric, pulverized coal reactor are compared with detailed velocity measurements. The reactor is down-fired and cylindrical with a radius of 75 cm and an axial length of 2.4 m. Three challenging areas for modeling are investigated, namely grid independence, inflow boundary conditions, and turbulence. The predictions are compared with LDA data obtained at radial profiles in the quarl and at various axial locations throughout the reactor. These velocity maps for the reactor were obtained at three swirl settings at an equivalence ratio of 0.9. Two readily available combustion CFD codes were used, FLUENT and PCGC-3. Proper grid resolution is shown to be particularly important in the flame region. Grid independence for the primary glow structures was achieved for the laboratory reactor. The gross characteristics of the CFD solutions are less sensitive to inflow BCs than expected. The standard kappa-epsilon two-equation model was compared to an RNG base kappa-epsilon model and a non-linear kappa-epsilon model.
LDA, Gas Species and Temperature Measurements in a Pulverized Coal Flame
Pickett, L.M.; Jackson, R.E. and Tree, D.R.
Presented at the Spring Meeting of the Western States Section of the Combustion Institute, Sandia National Laboratories, Livermore, California, April 14-15, 1997. Funded by US Department of Energy/University Coal Research and ACERC.
A two-color Laser Doppler Anemometer (LDA) was used to obtain axial and tangential velocity information in a 0.2 MW pulverized coal flame. In addition to the reacting flow data, a study on velocity slop encountered when coal is used as a seed particle for LDA was performed. Detailed velocity measurements at the outlet plane of a geometrically identical burner were obtained for use as boundary conditions. Velocity data of this type is useful in understanding the nature of pulverized coal flames, particularly with regard to NOx formation, and in developing models for pulverized coal combustion. The reacting flow velocity measurements were obtained throughout the near burner region of the reactor for three swirl settings at an overall stoichiometric ratio of 1.1. The coal-flame velocity data was useful in characterizing the flame structure indicating a centerline flame at 0 swirl transitioning to a radially directed flame with a central recirculation zone at swirl settings of 0.5 and 1.5. The transition of the flame structure to a central recirculation zone was also seen at the burner exit plane in the non-reacting flow studies and was found to correlate with a decrease in measured effluent NOx. At the flow rates and accelerations experienced in this study, the coal particles were shown to have minimal velocity slip. The velocity measurements from this study in combination with gas species and temperature measurements to be reported elsewhere combine to make a rare and comprehensive data set suitable for comprehensive coal combustion modeling development.