Abstract
The application of bromide-blended coal combustion technology can effectively improve the total mercury removal efficiency in coal-fired power plants. However, the effects of bromine introduced into WFGD slurry on the mercury re-emission process were still unclear. In this paper, the effects of Br- on mercury re-emission were studied in a bench-scale simulated WFGD system. The results indicated that Br- had an inhibitory effect on Hg0 re-emission. The mercury re-emission could be promoted with higher temperature, lower pH and moderate sulfite concentration in aqueous phase in the presence of Br-. The underlying mechanism of the inhibitory effect of Br- on Hg0 re-emission was proposed by combining experimental UV–visible spectra analyses with theoretical quantum chemistry calculations. It was found that the formation of BrnHgSO3n- (n = 1–3) complex and HgBr2 suppressed the reduction of Hg2+. The reason was that the BrnHgSO3n- complex and HgBr2 were more stable than HgSO3, whose decomposition is the main cause of mercury re-emission in WFGD in the solvent. Since the bromide-blended coal combustion technology can both oxidize elemental mercury and inhibit mercury re-emission, it has a good performance on mercury removal.
Published Version
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