Synergistic Removal Effects of Ultralow Emission Air Pollution Control Devices on Trace Elements in a Coal-Fired Power Plant

The effects of air pollution control devices (APCDs) such as selective catalytic reduction systems, electrostatic precipitators (ESPs), seawater desulfurization (SWFGD) units, and wet ESPs (WESP) on the ultralow emissions of trace elements (TEs) in a 300 MW pulverized coal boiler system are studied to reveal the removal of TEs (As, Se, and Pb) in these facilities. The results show that the average synergistic removal efficiencies of As, Se, and Pb in the studied power plant are 97.26, 94.07, and 95.49%, respectively. The emission concentration of As, Se, and Pb did not exceed 0.17, 0.67, and 4.23 mu g/m(3), respectively. ESPs can capture a great part of As and Pb; most of the Se is removed in the SWFGD system and WESP. The flue gas temperature decreasing in the air preheater (APH) and flue gas cooling system facilitates particulate TE removal in the ESP. Seawater in the SWFGD system promotes the dissolution and removal of unfilterable TEs, making the SWFGD system more efficient than conventional WFGDs under some working conditions. The influence of the boiler load and sulfur content of coals on the migration and transformation characteristics of TEs has also been systematically studied. Burning coal with a higher sulfur content can improve the synergistic removal of Pb, and working under a low boiler load is beneficial to the synergistic removal of As, Se, and Pb by APCDs of power plants. Hopefully, this study can provide a reference for the removal of TEs under various operating conditions in power plants with different APCDs.