Further Results on Nitrogen Oxides Production in Combustion Zones

Abstract

—This paper summarizes experimental results obtained during the study of the production of nitrogen oxides in a well stirred reactor burning hydrocarbons. First, the particular problem of NO and NO₂ probing has been addressed, and it has been shown experimentally that NO → NO₂ conversion actually occurs within the probe; but this conversion does not explain all the NO₂ measured, and a less important consumption of NO_x NO + NO₂ also occurs. Second, Fenimore's “prompt NO” mechanism has been shown to be non negligible even for fuel lean combustion, at low residence times within the combustor. Some theoretical examination leads to the conclusion that both HCN production by CH + N₂ → HCN + N and CH₂+N₂ → HCN + NH should be considered. Experimental results have shown also that the “prompt NO” depends on the fuel used. Finally, a detailed study of water addition on the NO_x production with two different fuels at different equivalence ratio have shown that the water effect is not always purely thermal. In addition, it seems that this effect on the “prompt NO” can be well predicted using a chemical scheme involving the two reactions cited above.