Mercury Removal Performance Of Wet Flue Gas Desulfurization System And Mercury Release Characteristics Of Its By-products

With the popularity of wet flue gas desulfurization system (WFGD) in coal-firedpower plant, its by-product desulfurization gypsum also become one of the mainwaste of coal-fired power plants. It has great significance to co-removal of mercuryby wet flue gas desulfurization system for coal-fired power plants, while avoidingmercury release of their secondary byproduct. For current, there are some researchson mercury removal performance of wet flue gas desulfurization system in actualplant at domestic and abroad, but there have no systematic study of mercury releasecharacteristics of WFGD byproducts.For the above, in this paper, the inlet and outlet of flue gas mercury in threeactual power plant wet flue gas desulfurization system were sampled, using theOntario-Hydro method (OHM) and adsorption tube method. The removal effects ofgaseous elemental mercury, gaseous oxidize mercury and total mercury by WFGDwere analyzed. And the three WFGD system all have certain removal effect of fluegas Hg, in which a good removal effect of gaseous oxidize mercury, due to thereduction of desulfurization slurry, the gaseous elemental mercury content of outletmay be greater than the inlet. The samples in actual wet flue gas desulfurizationsystems throughout the slurry process were collected, and the Hg content wasanalyzed, the mercury in slurry mainly enriched in gypsum, while desulfurizationwastewater has low mercury content. Desulfurization gypsums sampling from the sitewere heat in different ways, mercury in gypsum is heated to release and the mainlyrelease range in heating process is100℃~400℃, and the weight loss of gypsumhas no synchronization of mercury releases, the initial gypsum without deionizedwater handling has high Hg release rate than the gypsum leach residue when heatingto the same temperature. The proportions of mercury chemical form in gypsum wasdetermined by mercury release rate in certain heating temperature. Finally, the kineticparameters of mercury in gypsum during heating process were calculated.