Emission control of an ammonia-air flame in a coaxial tangential injection combustor at elevated pressure conditions

This study is the first to present the emission characteristics of the fuel staging method for a pure ammonia-air flame using a coaxial tangential injection combustor. The primary combustor used in this study had the same swirl number of 3.3 as in a previous study; however, the dimension of the combustor was increased to examine at a higher thermal load. The emissions of NO, NO₂, N₂O, and NH₃ were measured simultaneously under an elevated pressure. Consequently, secondary ammonia injection (fuel staging) was confirmed to be effective for NO_x abatement even under pressurized conditions. In addition, excessive secondary ammonia injection exhibited an additional NO_x reduction effect coupled with the generation of unburned N₂O and NH₃. The optimized amounts of NO_x, N₂O, and NH₃ were 83, 23, and 11 ppm (@15 % O₂, dry), respectively. The results of this study are expected to be useful as significant design and operating data for pure ammonia gas turbines.