Effect of NH3 Addition into CH4/air Swirl Flames on NO Emission Characteristics

摘要

NO emission characteristics of turbulent non-premixed CH4/NH3/air flames at a rich-lean two-stage combustor were numerically studied over wide range of primary zone global equivalence ratios(Φ_(global/pri)of 0.6~1.4),while varying the ratio of NH3 addition into CH4/air flames.NH3 was added into CH4 in terms of energy fraction(E_(NH3))by considering the lower heating values of both fuels.In this study two cases(E_(NH3)of 20 % and 40%)were calculated over wide range ofΦ_(global/pri),and found that NO emissions,in lean and stoichiometric conditions,are significantly higher than that of single CH4/air and NH3/air flames,however,at far-rich conditions(Φ_(global/pri)of 1.3~1.4)minimum NO emission level,on the order of 300 ppm,was achieved.This study found that NO emission characteristics in CH4/NH3/air flames were strongly related into the local OH and local temperature characteristics in the flame.