Numerical investigation of the laminar burning velocity and adiabatic flame temperature phenomenon for NH3/Hydrogen rich coal gases (HRCGs)/air flames

Abstract

This paper deals with improving the combustion performance of NH3 by mixing it with hydrogen-rich coal gases (HRCG). To this aim, temperature and NO emission profiles of NH3/Coke Oven Gas (COG) and NH3/Water Gas (WG) fuel mixtures were investigated. In addition, adiabatic flame temperature and laminar burning velocity (LBV) characteristics of the mixtures were also predicted, and all results obtained were compared with the predictions of the NH3/air blend. Adding COG or WG increased LBV and adiabatic flame temperature values consistent with the increasing amounts of HRCG in the fuel mixtures. For 45% mixing ratios of HRCG, the maximum LBV value of NH3/air increased by 216% and 149% whereas its' maximum adiabatic flame temperature value increased by 5% and 4% when mixed with COG or WG, respectively. In addition, blending the NH3/air mixture with HRCG increased temperature distributions within the combustor. However, this promoted the NO formation of NH3/air flame. The main reason for the increase in NO emissions is that adding HRCG into the NH3/air mixture triggered the decomposition of NH3 in the fuels and caused higher flame temperatures. This finding was confirmed by estimating the concentrations of O, OH, and HNO radicals in the flame zone.