Correlation between Polycyclic Aromatic Hydrocarbon Concentration and Particulate Matter during the Removal Process of a Low-Low Temperature Electrostatic Precipitator

To check the relation between polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM), this study chose a low-low temperature electrostatic precipitator (LLT-ESP) in an ultra-low-emission coal-fired power plant to study the mechanism at two operation conditions. Sixteen U.S Environmental Protection Agency PAHs in filterable and condensable PM were analyzed. The removal efficiency of the LLT-ESP for filterable PM2.5 was 98.8% and 98.4% at two different stages. The removal efficiency of the LLT-ESP for condensable PM was 77.1% at high temperature and 89.6% at low temperature. The boiler load markedly affected the emission of filterable PM, condensable PM, and particle-associated PAHs. The PAHs' concentration distribution was related to the PM concentration distribution. The mass concentration of total PAHs and the proportion of 5-ring and 6-ring PAHs in filterable PM2.5 increased significantly when the flue gas passed through the LLT-ESP. The 3- and 4-ring PAHs accounted for the main part of condensable PM in the flue gas at the inlet and outlet of the LLT-ESP. The PAHs distribution in filterable PM2.5 was not only influenced by the mass concentration of filterable PM2.5, but some other factors might also have had an effect. The 5- and 6-ring PAHs in FPM2.5 were more significantly related to mass concentration of filterable PM2.5 than were the 2-, 3-, and 4-ring PAHs. The coefficients of determination (COD, R-2) between the PAH content and the concentration of condensable PM were close to 1. The mass concentration of CPM and the PAH contents are thus strongly correlated. The LLT-ESP had a greater influence on the PAHs distribution in the FPM than it did in the CPM.