Characteristics of condensable particulate matter before and after wet flue gas desulfurization and wet electrostatic precipitator from ultra-low emission coal-fired power plants in China

Abstract

Total particulate matters emitted from coal-fired power plants generally include condensable particulate matter (CPM) and filterable particulate matter (FPM). Based on the on-site sampling of CPM, this study investigated four typical coal-fired power plants equipped with ultra-low emission facilities in north China. In order to clarify the characteristics of CPM before and after wet flue gas desulfurization (WFGD) and wet electrostatic precipitator (WESP), the mass concentrations, organic and inorganic compositions of the CPM were analyzed. Among the four test power plants, the emission concentrations of CPM were 2.20–7.33 mg/Nm3, accounting for 57.74–91.79% of PM2.5. The organic component accounted for 59.64% of the total mass concentration of CPM on average. Alkanes, esters and amides were the major organic components. And the water-soluble ions contributed significantly to the inorganic component of CPM. The proportion of SO42− was the highest, followed by Cl− and NO3−. In addition, this study found that the concentration of SO42− increased significantly while SO3 decreased from WESP inlet to outlet. It was indicated that ultrafine particles and soluble SO2 in flue gas could contribute to the formation of SO42− in CPM besides SO3. As an important part of CPM, further studies should be conducted on the factors affecting SO42−.