Study Of Characterization And Mechanism Of Mercury Adsorption By Fly Ash From Coal-fired Power Plant

There are thousands of coal-fired power plants in China, which is the largest stationary source of mercury emission in Asia.Thus, the control of coal-fired power plant emissions of mercury to the atmosphere has a very important practical significance. Many research about the control of the mercury emission from coal-fired power plant showed that activated carbon injection is most mature in the existing mercury removal technology. However, due to the high cost of activated carbon and the adverse effects to the utilization of the fly ash, this technology is difficult to be adopted. In recent years, fly ash injection technology began to be focused.Recent research has showed that fly ash produced from Coal-fired power plants play a very important role in mercury removal. The goal of this work is to study the relationship between fly ashes produced from different conditions and their mercury adsorption capacity. In order to achieve this objective, elemental analysis, Brunauer-Emmett-Teller(BET)surface area, scanning electron micrographs (SEMs), thermogravimetric (TG) analysis were employed to analysis the samples.The results indicated that the smaller average pore size of fly ash is the most important factor and the structure of residual carbon also may play the second important factor to capture the mercury in the flu gas. However, the addition of HBr with fly ash can remarkably enhance the mercury adsorption capability of fly ash.In addition, the results showed that the mercury adsorption characters of the fly ash has a good relationship with the chemical composition and the physical characters(distribution of the pore size and BET surface area).The temperature also has a obviously influence to the mercury adsorption. In order to improving the mercury adsorption of the fly ash, chemical impregnation method was used to modify the fly ash samples. The experiment showed that the mercury capture efficiency for the modified fly ashes are different.The active-site on the modified fly ash may play the most important role.