Study Of Low Nitrogen Combustion And Denitration Reform

In this paper,the low nitrogen combustion and denitration transformation project of #1 boiler were studied,and the boiler performance was test after the transformation.Beside improving the safety and economy of the unit operation,we need to reduce the pollutant discharge and meet the requirements of the state.Furnace denitration renovation project are using urea pyrolysis and selective catalytic reduction denitration system of flue gas.SCR flue gas denitration system uses high ash section arrangement.SCR reactor was arranged between the boiler economizer and air preheater,and urea pyrolysis was used as denitration reducing agent.The efficiency of the design of denitration system is 40%,and the final NO_X emission concentration is less than 180 mg/m3.Ammonia escape rate should not be greater than 3ppm.Due to the cancellation of the bypass of the desulfurization system,in order to ensure the safety and reliability of the operation of the unit,the induced draft fan and the booster fan are combined,and only two fans are installed in the flue system.The low nitrogen combustion renovation project,two original EI-DRB were all removed,reinstall manufactured two mixed collocation swirl burner of the Beijing Babcock & Wilcox company(DRB-4Z and Airejet).In order to realize the low nitrogen boiler combustion,the main combustion zone used the "oxygen combustion",double wind zone NO_X nozzle achieved grade greater air supply,and further realize the coal combustion,reducing the emission of NO_X.The adjustment process is mainly through two stages.The first stage is the NO_X emission concentration of coal economizer.In the second stage,we should pay attention to the boiler efficiency and increase the NO_X emission concentration.Experimental results show that if NO_X was used as the control index,NO_X concentration of #1 boiler economizer outlet can be lower than the design value of 295mg/m3,but the CO emission concentration was more than 1000 ppm,the carbon content of fly ash was 3.5% ~ 4%,high carbon content in slag was from 7% to 15%.If the thermal efficiency was the main control index,NO_X concentration of economizer outlet exceeded the design value of 10mg/m3 ~ 30mg/m3,CO emission concentration was lower than 1000 ppm,the carbon content of fly ash was 2.5% ~ 3.5%,high carbon content in slag was 3% ~ 10%.There was no obvious phenomenon of coking in boiler #1.At the high and medium load,the steam parameters can reached the design value.When the load was low,the reheat steam temperature was lower than the design value of 10?,the water amount increased.The DRB-4Z combustion effect of D and E coal mill was worse.