Cooperative Retrofit Of CFB Boiler Flue Gas Desulfurization And Dust Removal With Ultra-low Emission

In the process of production and operation of coal-fired boilers,the flue gas discharged contains a large number of pollutants harmful to human beings and the environment,such as dust,sulfur dioxide,nitrogen oxides and so on.With the improvement of emission standards of flue gas pollutants by national environmental protection departments,how to achieve ultra-clean co-emission of flue gas pollutants is an urgent problem faced by coal-fired thermal power enterprises.How to reduce SO₂ emission and solve the coordinated removal of dust is a difficult problem in the technical transformation of ultra-low emission of flue gas.In this paper,the flue gas treatment system of 410t/h CFB boiler?circulating fluidized bed boiler,the same below?in a large state-owned ethylene refinery in Guangdong Province is taken as the research object,and the technical route and measures for the technical transformation of ultra-low emission of flue gas are studied.Through the transformation practice,the purpose of ultra-clean emission of flue gas is achieved.The desulfurization unit was built after the original boiler system at the end of 2014,but it is still far from the special emission limits of atmospheric pollutants?NO_X?50mg/Nm3,SO₂ 35mg/Nm3and smoke10mg/Nm3)of the new national standard for the discharge of atmospheric pollutants from thermal power plants?GB13223-2011?in key areas.The big gap.In order to meet the new national emission standards,it is necessary to complete the transformation of the original boiler desulfurization and dust removal system economically and time-saving under the constraints of funds,sites and construction cycle.Based on the theoretical knowledge of desulfurization and dust removal technology,this paper analyses the characteristics of several main desulfurization and dust removal technologies at home and abroad,and combines the existing practical conditions of the project:?1?the existing site of the project is very compact;?2?the whole construction cycle is very tight?it must be completed synchronously with the overhaul of the boiler?;?3?In the case of limited funds,according to the existing conditions of the boiler desulfurization and dust removal environmental protection device in the plant,on the premise of not hindering normal production and operation in principle,and under the expected conditions of ultra-low flue gas emissions,the original device will be greatly reduced or increased.Two sets of feasible technical schemes are specially compared and analyzed:one is dust collector reform+efficient desulfurization and cooperative dust removal,the other is dust collector reform+wet dust removal.Because of the site conditions and other factors,the composite dust removal scheme of electric bag is abandoned,and low temperature economizer+high frequency is preferred.Power supply transformation scheme.Through comprehensive analysis and comparison,the best transformation scheme is determined and implemented.The dust removal efficiency of flue gas emission and desulfurization efficiency reached 99.95%and99.63%after project renovation;under the condition that the current low-temperature economizer was not put into use,the dust emission concentration at the chimney was less than10 mg/m3?less than 5 mg/m3after putting into use?,and the SO₂ emission concentration was less than 5 mg/m3,which met the latest national environmental protection emission standards.?SO₂ emission concentration is less than 35 mg/m3,and smoke emission concentration is less than 10 mg/m3?.At the same time,the data of desulfurization and dust removal system before and after the reform are compared and analyzed,and the problems and solutions which easily affect the emission standards in the operation of dust collector and desulfurization tower are pointed out,which can provide experience and reference for the industry to reduce the emission of flue gas.