Abstract: In recent years,the requirement of environmental protection has become more and more stringent,and the task of energy saving and emission reduction in coal-fired power industry has become more and more arduous.The transformation of ultra-low emission of coalfired power plants is imminent.In this paper,three 220 t/h pulverized coal fired boilers were revamped with ozone denitration technology,and a series of debugging tests were carried out.With the help of flue gas analyzer and on-line detection system of power plant,the effects of O_3/NO molar ratio and initial concentration of NO_xon denitration effect were mainly explored.The experimental results show that the application of ozone denitration technology in the pulverized coal boiler has a very good denitration effect,and the removal efficiency of NO_x reaches more than 90%.The NO_x concentration at the outlet of the boiler fluctuates greatly with the boiler load.The boiler load increases and the NO_xconcentration at the outlet increases.If the boiler load decreases,the NO_xconcentration at the outlet also decreases,showing a positive correlation.The efficiency of ozone denitration increases with the increase of the molar ratio of O_3/NO and ozone dosage,but when the molar ratio of O_3/NO exceeds a certain value,the rate of ozone denitration increases slowly with the increase of ozone dosage.In ozone denitration technology,the denitration efficiency is less affected by the initial concentration of NO_x.When the molar ratio of O_3/NO reaches a certain value,the denitration efficiency can be guaranteed under different conditions of the initial concentration fluctuation of NO_x.The characteristic curve obtained in this experiment provides a basis for determining the optimum ozone injection quantity in the application of ozone denitration technology,that is,how to select the optimum O_3/NO ratio on the premise of ensuring the denitration efficiency.After the application of ozone denitration technology,the power plant passed 168 hours of test successfully.The concentration of NO_xin flue gas emission is stable below 50 mg/Nm~3,which meets the national ultra-low emission requirements.It can be seen that the use of ozone denitration technology to control the emission of NO_xin flue gas has a very good effect.