Effect of H2 enrichment ratio and N2/CO2 dilution on swirl-stabilized partially premixed H2/CH4/C3H8 SNG combustion

Abstract

This paper discusses the N2 and CO2 dilution effects and H2 enrichment ratio of H2/CH4/C3H8 synthetic natural gas (SNG). As H2 enrichment ratio increases, the dump plane temperature and the combustion zone temperature increase because of shortened length of H2 flame. Even with a shorter flame length and a narrower chemical reaction regime, NOx emissions increase at same heat load because energy density is inversely proportional to flame length. As the CO2 diluent has a higher specific heat than the N2 diluent, the flame temperature is more greatly reduced by the effect of diluent heat capacity. Even a small amount of CO2 dilution can effectively reduce NOx emissions. The H2 enrichment ratio increases the OH radicals in the flame due to the increase in flame temperature. In addition, the burning velocity increases because the reaction rate in the flame increases, resulting in a decrease in flame length. NOx emissions increase exponentially with respect to global OH∗ chemiluminescence intensity per heat load, and these fit well into a single line. The results show that N2 and CO2 diluents can be used in SNG turbine combustors to control NOx emissions and that the H2 enrichment ratio in SNG.