The effect of iodine additive and coal char on the heterogeneous decomposition of N2O and the generation of NO under high temperature

Abstract

Air-staged combustion can effectively reduce the production of NOx. In our previous research, some significant phenomena of NOx formation during the staged combustion were found. It was found that O radicals released from CO combustion may be responsible for NO formation. In this research, iodine is used to study the inhibition of O radicals’ formation, the decomposition of N2O and the formation of NO. In addition, char was also used to study the decomposition of N2O and the generation of NO. The results show that the use of iodine as an additive to inhibit the O radical released by CO combustion has successfully reduced the NO concentration, thus directly demonstrating the effect of O radical on NO production. But the consensus view in traditional research is that N2O and O reactions almost completely generate N2 and O2. It is also verified from the side that part of NO at the outlet of the down-fired furnace may come from the decomposition of N2O. In the actual operation of the boiler, the addition of iodine and other inhibitors may be able to reduce the role of NOx emissions effectively. The author also added coal char to the fixed bed experiment to better simulate the actual operating conditions of the boiler. It was found that the presence of coal char promoted the conversion of N2O to NO under combustion atmosphere. This experimental phenomenon requires further research and explanation. However, the theory of O radicals proposed by the author seems to be better explained.