Demercurization Property of Flue Gas Desulfurization Installations in Power Plants

Wet flue gas desulfurization (WFGD) is at present the most effective way of desulfurization in power plants. As a future potential installation for controlling multi-pollutants, its effect on mercury transformation and efficiency of removal has at present become a hot subject in the research of how to get mercury contamination under control. On-site tests of a WFDG installation of a 500 MW (thermal power) pulverized coal fired boiler were carried out with the Semi-Continuous Mercury Monitor (SCMM), by using the Ontario Hydro Method (OHM). Test results show that the removal efficiency of oxidized bivalent mercury may get as high as 89.24 %~99.1 %. An increase of the desulfurization liquid to flue gas (L/G) ratio is advantageous for raising the mercury removal efficiency of WFGD. Demercurization efficiency of WFGD may exceed 50 %, the crucial influencing factor being the share of bivalent mercury in the total mercury content. Less than 8% mercury oxide can be reduced to elemental mercury, influenced by HSO₄^- ions and metal ions present in the liquid; a higher SO₂ concentration boosts the reduction of mercury oxide.