| Mercury is one of the trace elements in the presence of coal, and it is emitted into the environment with the flue gas in the process of coal combustion. Because of its bioaccumulation and physiological toxicity, mercury pollution control is raised more attention. Mercury pollution caused by coal combustion, has been one of the major environmental problems in China, due to the coal-dominated energy structure. The research on mercury pollution controls technology has been actively carrying out by relevant government departments and scholars. This research is focused on elemental mercury removed by activated carbon in fabric filter, with the support of the National High Technology Research and Development Program (No:2008AA05Z305).The situation of coal consumption and mercury content in our country was described, the migration and transformation of mercury in the whole process of coal combustion was also explained. The factors affecting on elemental mercury removal by activated carbon both in entrained-flow adsorption reactor and fabric filter were studied, the mercury removal efficiency of dust cake on filter surface was analyzed in detail. The model of mercury sorption by activated carbon in the chamber of filter was established. The load of manganese oxide on activated carbon fiber was prepared and characterized, and the removal capacity of elemental mercury was studied.The elemental mercury removal capability in the entrained-flow adsorption reactor was investigated using activated carbon as adsorbent. The results showed that:the higher the adsorption temperature, the lower the elemental mercury removal efficiency. When the temperature were at 80℃,120℃,and 150℃, the elemental mercury removal efficiency of activated carbon were reached 46.3%,44.0% and 40.0% respectively。The mercury removal efficiency increases with the C/Hg ratio (mass ratio of injected carbon to mercury) increases, the mercury removal efficiency were 31.3%,34.7%,40.0%, under the C/Hg ratio at 4000,6000 and 8000 respectively The elemental mercury removal capability in fabric filter was investigated using activated carbon as adsorbent. The total amount of Hg0 adsorption in the fabric filter can be divided into two parts, the amount of Hg0 adsorbed by the activated carbon collected on the filter surface, and the rest removed by the activated carbon somewhere inside the fabric filter. The elemental mercury removal efficiency of fabric filter in the presence of dust cake on the filter surface was investigated in detail. The results showed that:the elemental mercury removal efficiency was significantly improved with the C/Hg ratio increases. The mercury removal efficiency of the activated carbon inside the fabric filter was 30.4%,34.6%,40.3%, under the C/Hg ratio at 4000,6000 and 8000 respectively. But, the mercury removal efficiency of the activated carbon particles collected on the filter surface only reached 3.65%,3.20%,3.66% respectively, The chamber of filter made a major contribution to the mercury removal efficiency, and the dust cake is only a small part of the role. The change of C/Hg ratio has little effect on the elemental mercury removal of the dust cake. Fabric filter can be used as activated carbon adsorption reaction sites, for reducing mercury emissions from coal-fired flue gas.Based on the results of elemental mercury removal by activated carbon in the entrained-flow reactor and fabric filter, the model of mercury sorption by activated carbon in the chamber of filter was established. The factors affecting the elemental mercury adsorption on activated carbon were discussed, such as:C/Hg ratio, particle diameter, flue-gas temperature, flue-gas velocity, mercury concentration, using the present adsorption model.The manganese oxide was loaded on the activated carbon fiber (ACF) by impregnating and sintering. The samples of ACF were characterized before and after loading, using TEM,XPS,XRD and FTIR. The results show that manganese oxide was well dispersed on the surface of ACF. The particle diameter was about 50nm. The presence of manganese form was MnO and MnO2. The amount of C-OH,C=O,COOH was increased after loading on the surface of ACF. The adsorption ability of elemental mercury before and after modification was also studied. The breakthrough time was greatly extended after loading. The concentration of impregnating solution had a significant effect on the content of manganese on ACF. The removal efficiency of elemental mercury reached the best when the manganese content on the ACF surface was 6.7at.%. The loaded ACF showed a good adsorption property of elemental mercury at 150℃. The initial concentration of elemental mercury has an impact on the removal efficiency of elemental mercury.It is shown that elemental mercury adsorption removal by activated carbon in the bag filter is physical adsorption. The adsorption model can predict the impact of operating parameters on the activated carbon adsorption of elemental mercury. The adsorption of elemental mercury by the loaded ACF is chemical adsorption. It can promote the adsorption removal of elemental mercury. This study has a practical significance in the removal of elemental mercury by fabric filter.
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