Research On Synergistic Control Technology Of High Temperature Corrosion And No_x Formation In Power Station Boilers

In recent years,as major companies have gradually strengthened their awareness of environmental protection,pollutant emissions from thermal power plants have attracted widespread attention.In order to solve the problem of pollutant emission,many power plants adopt the method of reducing the amount of O₂to reduce NO_Xemissions.Due to the low O₂content,the combustion of pulverized coal is insufficient,resulting in the formation of a large amount of reducing gas CO and corrosive gas H₂S,however the H₂S gas chemically react with the metal on the surface of the water wall causes high temperature corrosion of the water wall of the boiler,which in turn poses a serious threat to the safe operation of the boiler.This paper conducted a test on a 350MW unit boiler in a power plant.The method of combining field test and numerical calculation is adopted to reduce the gas content in the furnace flue gas by increasing the boiler operating O₂content.However,increasing the amount of operating O₂will lead to an increase in the NO_Xcontent,and then reduce the NO_Xcontent by adjusting the over fire air swing angle.Field tests and numerical calculations have shown that increasing the oxygen content to 3.72%can effectively reduce the CO gas concentration in the flue gas near the water wall to below 30000 ppm,and the H₂S concentration to below 200 ppm.After increasing the oxygen content,swinging the over-fire air up can effectively reduce the problem of the increase in nitrogen oxide content in the furnace caused by the increase in oxygen content.Combined with the SCR system,the emission of nitrogen oxides can be well controlled.In addition,the boiler burner air distribution system is retrofitted with near.wall air.The results show that the installation of near.wall air can increase the O₂content in the flue gas near the water wall around the furnace,and make the O₂content average is about 0.12 in the flue gas near the wall,and can reduce the temperature of the flue gas attached to the water wall of the main combustion zone from 1500K to about 1000K,and the installation of attached air effectively reduces the reducing gas CO and H₂S concentration.On the premise of ensuring the safe and economic operation of the boiler,the installation of near.wall air can reduce the phenomenon of tube burst due to high temperature corrosion of the water wall,and provide ideas for the treatment of high temperature corrosion of the water wall of the350MW tangentially rounded boiler.