Abstract: It is urgent to speed up the environmental protection transformation of coal-fired industrial boilers and effectively reduce the emission of air pollutants,especially the emission of nitrogen oxides.Air staged combustion technology is a low nitrogen combustion technology with significant emission reduction effect and low transformation cost,which has been successfully applied in a large number of utility boilers.In order to investigate the application effect of air staged combustion technology in pulverized coal industrial boiler,a 58 MW pulverized coal industrial boiler air staged transformation project of Coal Research Institute was studied and six nozzles were arranged on the side wall to realize air staged combustion.Through engineering test,the flue gas temperature and flue gas composition at three different sections( 10 sampling points for each section) and six measuring points in the double cone burnerwere measured by using special water-cooled sampling gun and high temperature resistant flue gas analyzer under the original working condition and staged combustion working condition.The results show that a high temperature and strong reducing atmosphere is formed after x = 0.3 m measuring point in the burner under the condition of air-staged combustion,which effectively inhibits the formation of NOxin the initial stage of combustion.This is because the oxygen in the burner is consumed rapidly under the air-staged condition,the combustion reaction rate of char is significantly reduced,the gasifications are significantly enhanced,and a strong reducibility is formed which effectively curbs the generation of NOx.The variation law of flue gas temperature and composition in different sections of the furnace shows that the temperature distribution of flue gas in the original working condition is generally high in the center and low in the outside,and the distribution trend of oxygen content is just opposite to that of temperature distribution. However,the air-staged combustion is affected by the strong reductive high-speed flame of burner and the air injection on the fire,the section temperature fluctuates greatly,and the jet center of the burner is lower in the middle section in the middle section.In the air-staged combustion,there is an obvious reduction zone in the furnace,which is characterized by high CO concentration in the center and low CO concentration on the outside,effectively reducing NOxgeneration in the furnace.The air-staged retrofit of 58 MW pulverized coal industrial boiler has created a reasonable oxygen deficient reduction zone in the burner and furnace,which has a good effect of low nitrogen.