Hydrogen concentration effects on a swirl-stabilized non-premixed burner using ammonia

Abstract

In the present paper, it was aimed to consume pure NH3 by using an existing non-premixed burner with H2 blending strategy, and to examine the temperature and NO emission profiles emerged in a model combustor for NH3/H2 and pure NH3 fuel compositions. The Mixture Fraction/PDF combustion model with a reduced reaction mechanism was used for the numerical modelling. During the experimental studies, a stable NH3/air flame was able to achieve by introducing H2 into the burner since NH3/air mixture has a low reactivity and needs a high ignition energy. However, any flashback or lift-off tendency was not observed for NH3/H2/air or NH3/air flames. The numerical and experimental results showed that H2 addition into NH3/air mixture provided higher temperature values both in the flame region and in the entire combustor. As the concentration of H2 in the mixture was raised, the flame approached towards to the burner outlet with increment effect in burning velocity. However, H2 addition into NH3/air mixture led to more NO emissions formation in the combustor. This can be attributed with that H2 addition promoted both thermal and fuelNO mechanisms because H2 addition induced to increase the decomposition rate of NH3 and flame temperature of NH3/air mixture. This finding was validated with the prediction of the concentrations of O and HNO radicals for all fuel compositions. Consequently, H2 introduction contributed to the flame stability of NH3/air mixture even if more NO formation was observed.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.