| Nitrogen oxides(NOx)is one of the major pollutants emitted by the coal-fired industrial chain furnaces.In recent years,the NOx emission standards have become increasingly stringent.Many existing coal-fired industrial chain furnaces are facing severe pressures for reducing emissions.In this thesis,the reasons for the high NOx emission of a 35 t/h coal-fired chain furnace in a plant are analyzed in detail,and a scheme for combined denitration reform using flue gas recirculation and SNCR technology using ammonia as a reducing agent is proposed.Through the method of adjusting the working condition of the modified boiler,the influence of the application of the flue gas recirculation coupling SNCR technology on the denitration effect of the industrial chain furnace was studied,and the conclusion was drawn:(1)The primary air adopts the delayed air distribution method,and the O2 concentration of the boiler furnace outlet decreases from 8.2 to 8.5%to 7 to 7.2%.The NOx concentration decreased from 380 mg/m3 to 340 mg/m3,and the denitration efficiency reached about 10%.Combined with flue gas recirculation technology,at a load of 35 t/h,a flue gas recirculation rate of 15%can achieve a denitration efficiency of 33%.Under the load of 30t/h and 25t/h,the flue gas recirculation rate reached 12%and 14%,respectively,reaching the denitration efficiency of 24%and 18%respectively.(2)Under the load of 35t/h,30t/h and 25t/h,the application of flue gas recirculation coupling SNCR denitration technology,the overall denitrification efficiency of the boiler reached 76%,68.6%and 62.5%,respectively,and the NOx emission concentration reached 200mg/m3 below.(3)After the circulating flue gas was introduced into the 35t/h,30t/h,25t/h load operation and put into the SNCR,there was no significant influence on the boiler efficiency,and the ammonia slip was below 8mg/m3. |
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