Abstract: Cement kiln is a typical industrial furnace with high pollution emission,and the cement industry has become the third largest source of NO_xemission.At present,a lot of research has been done on the application of fuel staged combustion technology in utility boilers at home and abroad,but less on cement kiln.According to the characteristics of staging combustion for high calcium environment in cement precalciner,the experimental study on NO removal by reducing gas CO was carried out in fluid bed reactor,and the effects of CO concentration,Ca O and temperature on the denitrification process of CO were studied.The reaction path of NO reduction by CO was simulated in a one-dimensional plug flow reactor.The results indicate that CO has a strong denitrification effect in reducing atmosphere,and CO concentration has a great influence on denitrification.With the increase of CO concentration,the NO reduction efficiency increases.The NO emission is effectively reduced with the increase of CO concentration,and when the CO concentration increases from 1% to 5%,the efficiency of NO reduction increases by 37.8%.During NO reduction by CO,the intermediate products such as NH and H are produced,and NH and H play an important role in the NO reduction by CO.HCN can be adsorbed on Ca O surface and reacts with Ca O.In reducing atmosphere,NH_3adsorbs on Ca O surface and reacts to form Ca(N) and finally forms N_2.NO is reduced to N_2mainly through four pathways,and the paths of NO→N_2O→N_2 and NO→HNO→NH→N_2 are the most important reaction paths.In the experimental temperature range,the increase of temperature promotes the reduction and denitrification of CO.Ca O has a strong positive catalysis on CO denitrification at 850℃