Carbon monoxide emissions from combustion of non-carbon-containing fuels

Abstract

This short communication was motivated by measurements of non-negligible CO emissions from NH₃-air premixed flames. Given that NH₃ contains no carbon atoms, we initially thought this indicated some error or cross-sensitivity in the measurement system. However, as shown here, CO is indeed present in the exhaust emissions and originates from atmospheric CO₂ conversion to CO during combustion. We also show that CO levels of order 10-200 ppm are possible under rich burning conditions. Given that rich staged burning is a promising approach for NO_x control, particularly for NH₃ combustion, these results show that some level of C1 chemistry is inherently present when utilizing real air, that models must include CO₂ in air for capturing this CO production, and that practical combustors must consider CO burnout processes as well when utilizing rich-staged designs.