| 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. |
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