Characteristic Analysis Of Fine Particles Removal And Simulation Of Efficiency Of WESP In Thermal Power Plants

With the speedy social and economic development, the electrical load increase rapidly in our country. Atmospheric pollution caused by coal-fired thermal power plants is getting serious. Especially in recent years frequent fog haze caused extensive concern of the public. Although dry electrostatic precipitators widely used in power plants greatly reduced the emissions of particulate matter, control effect of tiny particles,like PM2.5 and PM10, isn’t ideal. As a new and efficient dust removal technology, wet electrostatic precipitator(WESP) has attracted much attention to meet the new requirements on particulate emission state.In this paper experiments on particulate emission were done in a typical 660 MW thermal power unit equipped with a wet electrostatic precipitator. It’s ultrafine particle removal effect was compared to coal-fired power plants without WESP.The characteristics of particulate matter were anakysised under different load conditions or burning different kinds of coal,finally coming to following conclusions. WESP has very obvious effect with taking out fine particles in coal-fired power plants. Particulate emission concentration be guaranteed under 3 mg/m3, which can meet the requirements of national standards.Particulate emission concentration be guaranteed under 3 mg/m3 in coal-fired power plants equipped with a WESP,which can meet the requirements of national standards.And there are some connections between particle removal efficiency of WESP and load or coal. Dust removal efficiency of WESP decreased with the increasing of load and ash content of coal. According to the feature analysis of the particles,WESP has obvious effect in terms of removing fine particles smaller than 30μmAt the same time,fine particle removal efficiency and some influences of WESP were learned through numerical simulation. Wet electrostatic precipitation model based on 660 MW coal-fired power plants was constructed by using related software.The fluence of spray water and effect factors of dedusting efficiency were explored,like gas flow speed, inlet dust concentration, the electric voltage and spray rates,which came to conclusions as follows.It’s obvious that spray water can improve dust removal effect. Dust removal efficiency decrease with the increasing of gas flow speed between 0.5 m/s to 3.5 m/s,and is in direct proportion to the electric voltage from 10 k V to 50 k V. When the concentration of particles keeps increasing between 2mg/m3 and 300mg/m3, the dust removal efficiency increases quickly,and almost remain the same when the concentration become higher than 30mg/m3. And efficiency can reach the highest level when water is sprayed under the flow rate of 0.05kg/s. The dust removing of WESP under different load conditions were simulated,and the transformation law of the results basically coincides with actral transformation ratio.