Advanced reburning measurements of temperature and species in a pulverized coal flame

An experimental program has been completed where detailed measurements of a pulverized coal flame with advanced reburning have been obtained. Maps of species (CO, CO2, O2, NO, HCN, and NH3), temperature, and velocity have been obtained consisting of approximately 60 measurements across a cross sectional plane of the reactor. Two maps at a single operating condition were obtained and are compared. In addition to the mapping data, effluent measurements of gaseous products were obtained for various operating conditions, while investigating the affect of reburning zone stoichiometric ratio (SR), ammonia nitrogen to NO ratio (NSR), ammonia injection location, and burner swirl. ed reburning was achieved by injecting natural gas downstream of the primary combustion zone to form a reburning zone followed by ammonia injection and then tertiary air. The data showed advanced reburning was more effective than either reburning or NH3 injection alone. At one advanced reburning condition (SR=1.05, Swirl=1.5, NSR=2.5) over 95% NO reduction was obtained. Ammonia injection was most beneficial when following a reburning zone which was slightly lean, SR=1.05, but was not very effective when following a slightly rich reburning zone, SR of 0.95. In the cases where advanced reburning was most effective (reburning SR=1.05), higher NSR values improved NO reduction, but the effect of NSR was secondary to NH3 injector location. The optimal location for injection was found to coincide with changes in the temperature field. pped 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.