Study On Flue Gas Desulfurization,Denitrification And Dust Removal Of 25 Tons Of Coal-fired Boiler In Yuncheng Fertilizer Company

The flue gas emissions from the coal-fired boiler is one of the main source of air pollution.The standards for the discharge of flue gas from coal-fired boilers have been gradually raised.In this work,we have studied the desulfurization,denitrification and dust removal of 25 tons flue gas from coal-fired boiler in the Yuncheng Fertilizer Company in view of the current situation of the sulfurous compounds,nitrogenous compounds and flue gas pollutants exceeding the standard seriously.The technological route of desulphurization and denitrification of flue gas in coal-fired boilers was determined firstly.In this work,"desulphurization by ammonia+denitrification by the selective non-catalytic reduction(SNCR)+composite dust removal process by electric bag" was used to replace the existing "double-base desulphurization+water curtain dust removal" process.The transformation is divided into three parts:(1)the transformation of desulfurization system,which was mainly to transform the existing desulfurization tower,including the replacement and conversion of the tower body,the replacement of the internal materials of the desulfurization tower,the conversion and replacement of the desulfurization nozzle,the use of the glass flakes,the replacement of the old pumps and motors,etc.In addition,an appropriate mist eliminator was selected to screen the aerosol secondary particulate matter produced by ammonia desulfurization.The defogging system of this project includes circulating water washing spray layer,two-stage roof baffle defogger and two-stage high-efficiency wire mesh defogger;(2)a new denitrification system was built,which used the SNCR technology,including the preparation,storage and supply system of reducing agent,dilution water system and reductant injection system;(3)the renovation of the dust removal system,which changed the original water curtain dust remover into electric bag type composite dust remover and the emission concentration of flue gas dust was reduced from 10 mg/m3 to 30 mg/m3.In addition,the original bag filter separator,filter bag material,bag cage structure and top cover structure were modified to improve dust removal efficiency.After the above technical modification,the emission concentration of SO2,NOx and soot can be reduced to 100 mg/m3,100 mg/m3 and 30 mg/m3,respectively,which was meeting the emission concentration limit of atmospheric pollutants.The results also showed that the desulfurization efficiency is not less than 90%,and the denitrification efficiency is not less than 60%.This improved technique can reduce the emission of SO2 and NOx of 38.04 t/a and 10.22 t/a,respectively.The project have a good social and economic foundation and external cooperation conditions ensuring the normal production and operation of the fertilizer company.