Condensable particulate matter is the predominant contributor to the total particulate matter emissions of coal-fired power plants. In the studied ultralow-emission coal-fired power plant, the emission concentrations of condensable and filterable particulate matter in the stack were 1.6 mg/Nm3 and 7.9 mg/Nm3. The organic fraction in condensable particulate matter was mainly composed of alkanes, esters, and other complex organic compounds. The organic fraction comprised 54% of the total concentrations of condensable particulate matter tested at the stack. The organic fraction in condensable particulate matter might contribute significantly to the organic carbon in atmospheric PM2.5. SO4 2– accounted for the highest concentrations in the inorganic fraction of condensable particulate matter. Na and Ca were predominant metal elements in the inorganic fraction. The inorganic fraction of condensable particulate matter mainly contributed to the water-soluble ions in atmospheric PM2.5. The total particulate matter elimination effect of the air pollution control devices used in the studied plant was good. The removal efficiency of the electrostatic precipitator for condensable particulate matter was much higher than those of the wet flue gas desulfurization system and the wet electrostatic precipitator. The wet flue gas desulfurization system performed well in eliminating the inorganic fraction of condensable particulate matter. Further studies should be conducted on the pollutant control effects of the wet electrostatic precipitator. It is important to study the emission characteristics, chemical compositions, and control methods for condensable particulate matter from coal-fired power plants.

The low-low temperature electrostatic precipitator (LLT-ESP) has been developed recently to improve the performance of traditional low temperature electrostatic precipitators. In this study, the particulate matter emission characteristics and removal efficiencies of were investigated on an LLT-ESP. Filterable particulate matter (FPM) was tested according to ISO standard 23210-2009, and condensable particulate matter (CPM) was tested according to U.S. EPA Method 202. The LLT-ESP showed excellent removal efficiency for FPM, with total FPM removal efficiencies of more than 99.9%. The removal efficiencies of FPM increased with the rising particulate diameter; for FPM2.5, removal efficiencies ranged from 96.5 to 98.2%. The LLT-ESP also showed remarkable removal efficiencies for CPM, with CPM removal efficiencies of more than 60.9%. The removal mechanism of CPM in the ESP was different from that of FPM. After the LLT-ESP, the quantity relationship between FPM and CPM reversed. For further reduced emission of PM for coal-fired power boiler units, more attention should be paid to the control of CPM. The load of the unit showed significant effects on CPM. CPM was generated more in lower unit loads for incomplete combustion of coal, and the organic fractions accounted for more than 65% of total CPM in the inlet flue gas of the LLT-ESP. SO4 2– was the main contributor of anions, and Cl– took second place. Na+ and Ca2+ were the main contributors of metal ions.

The low-low temperature electrostatic precipitator (LLT-ESP) is one of the most used devices for pollutant control in ultra-low emission coal-fired power plants. This study investigated the influence of the LLT-ESP on polycyclic aromatic hydrocarbons (PAHs) distributions in flue gas from an ultra-low emission coal-fired power plant. The total gas-phase PAH concentration was reduced from 27.52 μg/m to 3.38 μg/m. The total particulate-phase PAH concentration decreased from 14.36 μg/m to 0.34 μg/m. The removal efficiency of the LLT-ESP for gas-phase and particulate phase carcinogenic higher molecular weight (HMW) PAHs was 85% and 99%, respectively. The total concentration of 16 selected PAHs in feed coal was 98.16 μg/g. The fly ash particle size successively decreased from Electric Field 1 (F1) to Electric Field 4 (F4). The total PAH concentration decreased from F1 to F2 but increased again from F3 to F4. The flue gas cooling process significantly contributed to the elimination of both gas- and particulate-phase PAHs in the flue gas. Presumably, most of the condensed PAHs were adhered to or absorbed in the fly ash and were scavenged in Field 1. Both gas- and particulate-phase 5- and 6-ring PAHs in the flue gas were completely removed in Field 1. The discharge process in the electric fields may promote the formation of several 4- or 5-ring PAHs. In this study, benzo[k]fluoranthene (BKF) and benzo[a]pyrene (BaP) were regenerated in the particles rather than in the flue gas during the discharge process in the electric fields.