NO x reduction and NO 2 emission characteristics in rich-lean combustion of hydrogen

Abstract

Hydrogen is a clean alternative to conventional hydrocarbon fuels, but it is very important to reduce the nitrogen oxides (NO x ) emissions generated by hydrogen combustion. The rich-lean combustion or staged combustion is known to reduce NO x emissions from continuous combustion burners such as gas turbines and boilers, and NO x reduction effects have been demonstrated for hydrocarbon fuels. The authors applied rich-lean combustion to a hydrogen gas turbine and showed its NO x reduction effect in previous research. The present study focused on experimental measurements of NO and NO 2 emissions from a coaxial rich-lean burner fueled with hydrogen. The results were compared with diffusion combustion and methane rich-lean combustion. Significant reductions in NO and NO 2 were achieved with rich-lean combustion. The NO and NO 2 reduction effects by rich-lean combustion relative to conventional diffusion combustion were higher with hydrogen than with methane.