Stability Of Mercury From Simulated Wet Flue Gas Desulfurization

Mercury emissions from coal combustion accounts for 80% of total anthropogenic mercury emissions, however 33% of which comes from coal-fired power plants, waste water wet desulphurization coal-fired power plants from coal-fired power plants is one of the major sources of mercury, which cause great harm to human health and the environment, so study efflux desulfurization wastewater is essential. In this thesis, considering that Hg²⁺ in wet flue gas desulfurization（WFGD） systems can easily be reduced and then released into atmosphere, causing secondary pollution, the researches about the effects of desulfurization waste water on mercury complexes stability was carried out, in order to provide a theoretical basis for industrial application of mercury control in WFGD systems.Firstly, we test Hg²⁺-Cl^-, Hg²⁺-SO₃^2- and Hg²⁺-Cl^--SO₃^2- three types of system solution in desulfurization waste water system by the method of ultraviolet visible spectrum, and confirmed that Cl Hg SO₃^- is the Hg²⁺-Cl^--SO₃^2- mercury complexes of desulfurization waste water, Hg SO₃ is the Hg²⁺-SO₃^2- mercury complexes of desulfurization waste water, Hg Cl_n^2-n（n=1、2、3、4）is the Hg²⁺-Cl^- mercury complexes of desulfurization waste water. Then the stability of mercury complexes in the three kinds of solution system were detected, finally we made a conclusion that the mercury complexes in Hg²⁺-Cl^--SO₃^2- system has the strongest stability, while the mercury complexes in Hg²⁺-SO₃^2- system has the weakest stability. Cland SO₃^2- are main component of desulfurization wastewater, since the SO₃^2- belong to monodentate ligands, Cl^- belong to bridg ligand, desulfurization wastewater is easier to Hg2 +-Cl^--SO₃^2- solution system combined, so Cl Hg SO₃^- mainly in the desulfurization wastewater. we investigated the effect on the stability of solution system through changing temperature, p H;Our experiments results are consistent with the conclusions of UV spectra.Secondly, in order to further understand the effects of mercury complexes Cl Hg SO₃^-stability in the desulfurization waste water, we study wastewater oxidation and changes of Concentration of Ca²⁺, Mg²⁺, Cu²⁺, Fe²⁺, Mn²⁺, etc.We found factors break equilibrium system of Hg²⁺-Cl^--SO₃^2- possiblly,indirectly undermined the stability of Cl Hg SO₃^-.Finally, simulate the whole process desulfurization wastewater treatment by using Aspen Plus software, study the effects of factors on the total mercury removal efficiency and analyze its sensitivity of the results, in order to understand the impact of mercury through the desulfurization wastewater treatment process, in order to contribute to water treatment.