| Mercury emissions from coal fired power plant is getting more and more attention. Elemental mercury cannot be effectively removed using current air pollution control devices due to its low melting point, high equilibrium vapor pressure and low solubility in water. The technology of activated carbon injection from the tail of the boiler is a good mercury control technology at the present stage. It is great scientific significance and social value for the development of cheap and efficient mercury removal adsorbent due to the high cost of activated carbon.This research targets on the development of good magnetic properties and high-efficiency sorbents,magnetic activated carbon,which were produced by using different ion ratio and different magnetic content in preparation of adsorbent. MAC was characterized by BET surface areas measurements, Vibrating sample magnetometer(VSM), scanning electron microscope(SEM),X-ray diffraction(XRD) and Thermogravimetric Analysis(TGA). It provide the basis for exploring the MAC to remove the mechanism of mercury.The experiments were conducted on a bench-scale fixed-bed test rig with intensive focus on the variable flue gas components and compositions. To understand the interaction and competitive adsorption of different gas components well,these gases(O2,SO2,HCl and moisture) were introduced.The results show that y-Fe2O3 is on the main magnetic materials on the MAC.The mercury adsorption capacity of MAC gradually improves as the O2 and HC1 concentration increases. The content of SO2 had no obvious effect of Hg removal, early reaction appear Competitive adsorption phenomenon caused by the adsorption efficiency lower. The presence of water vapor significantly inhibited the mercury adsorption effect of adsorbent.In order to further enhance the adsorption properties of MAC, the modified activated carbon adsorbent from NaCl、CuCl2、NaBr、CuBr2 were selected. By performance characterization, the modification of activated carbon has no effect on the magnetic properties of MAC. And CuCl2,CuBr2 mainly loaded in the form of Cu2Cl(OH)3 and Cu2Br(OH)3 on the modified activated carbon. The use of bromide modification effect is better than that of modified chloride. The oxidation of Hg0 had been significantly improved after impregnated by the Cu-based sorbents. And the concentration of 5% CuBr2 solution is the best.The experimental method for the separation of wet and dry magnetic separation of the best modified MAC. The recovery rate and purity of MAC were tested. The results showed that the wet process and dry process had a higher recovery rate. The wet separation operation process was complex, and the mercury removal performance of modified MAC was reduced, while the dry magnetic separation can get higher recovery and recovery purity. |
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