Adam, WC
1998
Detailed In-Situ Measurements of Temperature and Species in a Pulverized Coal Flame with Advanced Reburning
Adam, W.C. and Tree, D.R.
Western States Section of the Combustion Institute, Seattle, Washington, October 26-27, 1998.
An experimental program has been completed where detailed measurements of a pulverized coal flame with reburning and advanced reburning have been obtained. Maps of species (CO, CO2, O2, NO, HCN, and NH3), temperature and velocity have been obtained which consist of approximately 60 measurements across a cross sectional plane of the reactor. Two maps at a single operating condition have been obtained and are compared. In addition to the mapping data, effluent measurements of gaseous products were obtained for various operating conditions.
Advanced reburning was achieved in the reactor by injecting natural gas downstream of the primary combustion zone to form a reburning zone followed by a second injection of ammonia downstream of reburning to form an advanced reburning zone. Finally, downstream of the ammonia injection, air was injected to form a burnout or tertiary air zone. The amount of natural gas injected was characterized by the reburning zone stoichiometric ratio. The amount of ammonia injected was characterized by the ammonia to nitrogen stoichiometric ratio or NSR and by the amount of carrier gas used to transport and mix the ammonia. A matrix of operating conditions where injector position, reburning zone stoichiometric ratio, NSR, and carrier gas flow rate were varied and NO reduction was measured in addition to two maps of data at one operating condition.
The data showed advanced reburning was more effective than either reburning or NH3 injection alone. At one advanced reburning condition over 95% NO reduction was obtained. Ammonia injection was most beneficial when following a reburning zone which was lightly lean, S.R. = 1.05, but was not very effective when following a slightly rich reburning zone, S.R. of 0.95. In the cases where advanced reburning was most effective (reburning S.R. = 1.05), higher NSR values improved NO reduction but the NSR was secondary to NH3 injector location. The optimal location for injection was found to coincide with changes in the temperature field.
The mapped temperature, species and velocity data for advanced reburning showed that the largest drops in NO occurred in a region where the O2 concentration was between 0.7 and 3.0%, NH3 was between 0 and 2961 ppm, and temperatures were between 1274 and 1343 K. These are similar to optimal conditions known for SNCR. Significant NO reductions were seen when NSR values were near one, suggesting NH3 was very effective at NO reduction when surrounding temperature and species conditions were favorable. Because this was only one detailed set of data, it is difficult to conclude that these conditions are optimal or need to exist for optimal NO reduction. More detailed mapping data at other operating conditions would be useful in identifying optimal advanced reburning conditions.
Adam, WC
1998
Detailed In-Situ Measurements of Temperature and Species in a Pulverized Coal Flame with Advanced Reburning
Adam, W.C. and Tree, D.R.
Western States Section of the Combustion Institute, Seattle, Washington, October 26-27, 1998.
An experimental program has been completed where detailed measurements of a pulverized coal flame with reburning and advanced reburning have been obtained. Maps of species (CO, CO2, O2, NO, HCN, and NH3), temperature and velocity have been obtained which consist of approximately 60 measurements across a cross sectional plane of the reactor. Two maps at a single operating condition have been obtained and are compared. In addition to the mapping data, effluent measurements of gaseous products were obtained for various operating conditions.
Advanced reburning was achieved in the reactor by injecting natural gas downstream of the primary combustion zone to form a reburning zone followed by a second injection of ammonia downstream of reburning to form an advanced reburning zone. Finally, downstream of the ammonia injection, air was injected to form a burnout or tertiary air zone. The amount of natural gas injected was characterized by the reburning zone stoichiometric ratio. The amount of ammonia injected was characterized by the ammonia to nitrogen stoichiometric ratio or NSR and by the amount of carrier gas used to transport and mix the ammonia. A matrix of operating conditions where injector position, reburning zone stoichiometric ratio, NSR, and carrier gas flow rate were varied and NO reduction was measured in addition to two maps of data at one operating condition.
The data showed advanced reburning was more effective than either reburning or NH3 injection alone. At one advanced reburning condition over 95% NO reduction was obtained. Ammonia injection was most beneficial when following a reburning zone which was lightly lean, S.R. = 1.05, but was not very effective when following a slightly rich reburning zone, S.R. of 0.95. In the cases where advanced reburning was most effective (reburning S.R. = 1.05), higher NSR values improved NO reduction but the NSR was secondary to NH3 injector location. The optimal location for injection was found to coincide with changes in the temperature field.
The mapped temperature, species and velocity data for advanced reburning showed that the largest drops in NO occurred in a region where the O2 concentration was between 0.7 and 3.0%, NH3 was between 0 and 2961 ppm, and temperatures were between 1274 and 1343 K. These are similar to optimal conditions known for SNCR. Significant NO reductions were seen when NSR values were near one, suggesting NH3 was very effective at NO reduction when surrounding temperature and species conditions were favorable. Because this was only one detailed set of data, it is difficult to conclude that these conditions are optimal or need to exist for optimal NO reduction. More detailed mapping data at other operating conditions would be useful in identifying optimal advanced reburning conditions.