Markham, JR
1990
Structure of a Near-Laminar Coal Jet Flame
Brewster, B.S.; Smoot, L.D.; Solomon, P.R. and Markham, J.R.
Tenth Annual Gasification and Gas Stream Cleanup Systems Contractors Review Meeting, Morgantown, WV, 1990. (Also Presented at the Western States Section/The Combustion Institute, San Diego, CA, 1990). Funded by Morgantown Energy Technology Center and Advanced Fuel Research Co.
An advanced 2-D model for pulverized-coal combustion has been modified and applied to a laminar coal flame in a transparent wall reactor. Modifications were made to allow for the up-fired flow configuration, laminarization, and gas buoyancy. A laminarization extension to the k- turbulence model was incorporated. Particle dispersion is sensitive to laminarization and to the value of turbulent particle Schmidt number. Predicted particle velocity and residence time are sensitive to the inclusion of gas buoyancy, which increases the velocity in the center of the reactor and induces a radial, inward flow. Model predictions have been compared with flame measurements to evaluate the comprehensive model that incorporates an advanced devolatilization submodel. Predicted velocities of burning particles agree well with values determined from particle streaks on video recording. Good agreement was also obtained between measured and predicted particle burnout. Discrepancies between measured and predicted particle and gas temperature may be due to neglecting heterogeneous formation of CO2 and the variation of char reactivity with extent of burnout. Discrepancies between predicted bulk gas temperature and measured CO2 gas temperature in the ignition zone can also be explained by the fact that the combustion energy first heats the CO2 that subsequently heats the other gases. Soot decays more slowly than predicted from equilibrium concentrations of condensed carbon.
Markham, JR
1990
Structure of a Near-Laminar Coal Jet Flame
Brewster, B.S.; Smoot, L.D.; Solomon, P.R. and Markham, J.R.
Tenth Annual Gasification and Gas Stream Cleanup Systems Contractors Review Meeting, Morgantown, WV, 1990. (Also Presented at the Western States Section/The Combustion Institute, San Diego, CA, 1990). Funded by Morgantown Energy Technology Center and Advanced Fuel Research Co.
An advanced 2-D model for pulverized-coal combustion has been modified and applied to a laminar coal flame in a transparent wall reactor. Modifications were made to allow for the up-fired flow configuration, laminarization, and gas buoyancy. A laminarization extension to the k- turbulence model was incorporated. Particle dispersion is sensitive to laminarization and to the value of turbulent particle Schmidt number. Predicted particle velocity and residence time are sensitive to the inclusion of gas buoyancy, which increases the velocity in the center of the reactor and induces a radial, inward flow. Model predictions have been compared with flame measurements to evaluate the comprehensive model that incorporates an advanced devolatilization submodel. Predicted velocities of burning particles agree well with values determined from particle streaks on video recording. Good agreement was also obtained between measured and predicted particle burnout. Discrepancies between measured and predicted particle and gas temperature may be due to neglecting heterogeneous formation of CO2 and the variation of char reactivity with extent of burnout. Discrepancies between predicted bulk gas temperature and measured CO2 gas temperature in the ignition zone can also be explained by the fact that the combustion energy first heats the CO2 that subsequently heats the other gases. Soot decays more slowly than predicted from equilibrium concentrations of condensed carbon.