Effect of dilution of fuel in CO2 on the conversion of NH3 to NO x during oxy-fuel combustion

Abstract

Abstract:The indirect chemical effects of fuel dilution by CO 2 on NO formation were investigated numerically in this paper. CH 4 doped with NH 3 was used as fuel, while CO 2 and O 2 were mixed as oxidant. The dilution effect of CO 2 was then investigated through adding extra CO 2 to the reaction system. An isothermal plug flow reactor was used. An unbranched chain reaction mechanism is proposed to illustrate the chemical effects of CO 2 on the H/O/OH radical pool and NO x . Due to the reaction between CO 2 and H, extra NO will be formed in fuel-rich conditions, while NO will be inhibited in fuel-lean conditions and high CO 2 dilution conditions. The reaction affected the radical pools of OH, H, and O of the branched chain reaction, and then the formation and reduction of NO. The pool of H had the greatest effect on NO reduction. The results suggest that the indirect chemical effects on NO formation differ between diluted fuel oxy-fuel combustion conditions and normal oxy-fuel conditions.