Analysis of ammonia combustion for decarbonization followed by selective non-catalytic reduction of nitrogen oxides

Abstract

This study aimed to investigate the thermodynamics of ammonia combustion at engine conditions and subsequent selective non-catalytic reduction (SNCR) of the products, emphasizing the production of nitrogen oxides (NOX) through the minimization of Gibbs free energy. The results showed a good correlation with existing research about ammonia combustion and SNCR. NOX production increased with temperature, decreased with increasing ammonia equivalence ratio, and was largely independent of pressure. At the conditions with the highest NOX production, the NOX concentration peaked at 21,963 ppm. The ammonia combustion reaction was exothermic at high temperatures and had a reaction enthalpy that decreased with temperature and increased with an increasing ammonia equivalence ratio. Further, the SNCR simulation indicated that reducing large NOX concentrations produced during ammonia combustion could be thermodynamically favorable up to over 98% through selective non-catalytic reduction.