System Reform And Engineering Practice Of Flue Gas Dedusting, Denitrification And Desulphurization In A Thermal Power Plant

Pollutants such as dust,SO₂ and NO_X,emitted from flue gas,are the precursors of haze.Emission control of pollutants in coal burning has become an important measure to solve the problem of air pollution.Ultra-low emission and energy conservation transformation in thermal power plants which intend to reduce coal consumption and pollution emissions,are important content of conducting air pollution controlling activities and winning the‘blue-sky protection war'in nowdays.The optimization of flue gas purification in thermal power plants is a very complex process,including denitration,desulphurization,dedusting and so on.Therefore,the development of efficient and coordinated removal system of various pollutants is the core of ultra-low emission of air pollutants in thermal power plants.This paper analyzed the combination technology of SNCR,dry desulfurization and electrostatic dedusting.Through multi-link transformation and systematic optimization,the ultra-low emission of flue gas pollutants in thermal power plants was achieved.The optimization of denitrification involved circulating material system,air distributor,secondary tuyere,water cooling screen and overheating screen,etc.Ultra-low emission had been achieved by transformation measures of low-nitrogen combustion.After the transformation,NO_X emission concentration decreased from80mg/Nm³ to less than 50mg/Nm³.The optimization of desulphurization involved fuel quality control,in-furnace desulphurization and wet desulphurization,etc.The sulfur dioxide concentration decreased from 700mg/Nm³ to 11mg/Nm³ through wet desulphurization by limestone gypsum method.The optimization of dedusting included the selection of the dedusting route,the transformation of CEMS and the control of smoke and dust concentration,etc.With the transformation measures of electrostatic dedusting and wet electric dedusting,the dust concentration of flue gas decreased from 20mg/Nm³ to less than 5mg/Nm³.After the practice and implement of the transformation project of desulfurization,denitration and dedusting,the total emission of SO₂ was reduced more than 65%.The total emission of NO_X was reduced by about a half.The total emission of dust was reduced by more than 80%.The economic and environmental benefits of the thermal power plant were extremely improved.There is significance not only for the future development of this thermal power plant,but also for the optimization and development of other thermal power plants.