Effect of Cement Raw Material and Oxygen Concentration on SNCR Reaction

Abstract

As the selective non-catalytic reduction denitration(SNCR denitration) was used in cement decomposition furnaces under the high concentration cement raw materials and complex flue gas composition , the denitration efficiency is poor and the reducing agent is largely consumed.In order to meet the more stricter requirements of environmental protection, there is an urgent need to improve the denitration efficiency of SNCR and reduce the escape of reducing agentsin order to prevent the unnecessary waste caused by excessive use of reducing agents and secondary atmospheric pollution.Therefore, studying the effect of cement raw materials and O2 concentration on SNCR process is very important. In this paper, the initial concentration of NO and the ammonium to nitrogen ration (CNH3/CNO) was 800ppm and 1.5, respectively. The effects of cement raw material and oxygen concentration on the reaction process of NH3+NO+O2 in the temperature range of 750°C -1100°C were investigated by means of denitration rate, in Situ DRIFTS analysis.The results demonstrate when O2 concentration was 5% and denitration temperature was 950°C, the deNOx rate reached a maximum of 89.64%, which due to O2 promoted NH3 and NO to react with O2 to produce N2 and H2O. However,under the effect of cement raw material, O2 can promote NH3 which was adsorbed on the surface of cement raw material to react with O2 and produce NO and H2O, and the reaction of oxidation of NH3 is dominant, therefore, the denitration reaction is inhibited. .When O2 concentration was 5% and temperature was 850°C, the deNOx rate reached a minimum value of -109.09%. the high concentration cement raw material and flue gas composition reduce the denitration efficiency of cement kiln.