Experimental Research on Mercury Emission and Its Speciation in the Flue Gas from Coal-Fired Power Station

Mercury is harmful to our health and environment, so research on mercury emission from coal-fired power station, the main source of anthropogenic mercury emission, is very important. In this paper, mercury emission and speciation in the flue gas from a coal-fired power station was measured by three methods, i.e., OHM (Ontario Hydro method), Hg SCEM (semi-continuous emission monitors), and EPA Appendix K (carbon trap method). The effects of boiler load, flue gas characteristics on mercury emission and its speciation were analyzed. Mercury mass balance was calculated based on the analyses of mercury contents in coal, pyrite, bottom ash, fly ash, FGD (flue gas desulphurization) slurry, and flue gas at FGD inlet and stack. The results indicate that data by the three methods have good consistency within acceptable range. The total mercury emission increases with the increasing of mercury content in fuel and boiler load. The percentages of elemental mercury in the flue gas at FGD inlet and stack are around 26%-48% and 70%-85% respectively. Wet FGD would capture more than 80% of oxidized mercury.