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Migration and Emission Characteristics of Trace Elements in a 660 MW Coal-Fired Power Plant of China

Zhao, Shilin, Duan, Yufeng, Tan, Houzhang, Liu, Meng, Wang, Xuebin, Wu, Lituo, Wang, Chenping, Lv, Jianhong, Yao, Ting, She, Min, Tang, Hongjian
Energy 2016 v.30 no.7 pp. 5937-5944
air pollution, antimony, barium, bottom ash, byproducts, cadmium, chromium, coal, combustion, emissions, flue gas, flue gas desulfurization, furnaces, groundwater, gypsum, manganese, nickel, pollution control, power plants, silver, soil, wastewater, zinc, China, United States
Trace elements (TEs) emitted from coal-fired power plants have caused widespread concern. The onsite investigation of TEs emission from a Chinese 660 MW pulverized coal (PC) boiler equipped with selective catalytic reduction (SCR), electric submersible pump (ESP), wet flue gas desulfurization (WFGD), and wet electrostatic precipitator (WESP) was conducted by using U.S. Environmental Protection Agency Method 29. Simultaneous sampling of the coal, bottom ash, ESP ash, flue gas, and by-products from WFGD and WESP processes was performed. Results show that TEs mass balance rates for the entire system, furnace and each air pollution control device (APCD), are in the acceptable range of 70–130%, which confirms the validity and reliability of the field test data. The studied TEs are mainly distributed in bottom and ESP ash with the ratios of 2.11–12.15% and 87.83–97.83%, respectively, while little amounts of them exist in WFGD, WESP, and the stack. Coal combustion by-products such as bottom ash and gypsum have little influence on soil from the perspective of TEs while more attention should be paid to Ni, Zn, and Cd in the ESP ash. Waste water from WFGD should be treated carefully especially for Cr and Mn. WESP wastewater has no influence on groundwater except for Mn, Ag, and Sb. Zn, Ni, and Sb prefer to enrich in ESP ash while accumulation of Mn occurs in bottom ash. Ba is enriched in both bottom and ESP ashes. ESP has great removal efficiency for TEs with the value exceeding 99.87%. Both WFGD and WESP are capable of capturing TEs, which results in the overall removal rate across ESP + WFGD + WESP of more than 99.90%. TEs concentration in the flue gas emitted from the stack is extremely low with the range of 0.00–1.33 μg/m³. The ultralow-emission (ULE) coal-fired power plant equipped with SCR + ESP + WFGD + WESP has good effects on TEs emission control.