Experimental Study Of Mercury Removal With Wet Flue Gas Desulfurization System

At present, the power plant is the largest source regions that release mercury into the atmosphere,and mercury have already caused detrimental damage to human health. For the situation of our country, use the wet flue gas desulfurization(WFGD)to remove mercury is a future potential installation for controlling multi^-pollutants,it's not only get mercury contamination under control,but also cut down the cost. Therefore, it is necessary and important to reserach on mercury removal with WFGD devices.One objective of this work is to investigate the influence of scrubber parameters on mercury removal efficiency to establish effective measures for mercury control. The experiment result shows that the best operate temperature is 55°C. with the increase of pH, O₂ concentration and Slurry concentrations,the removal efficiency raise up. The results indicate that total mercury removal efficiency increases with a decrease SO₂ content. The result shows the Br^- has a higher mercury removal efficiency than Br^- or I^-.Another objective of this work is to investigate the reduction of Hg²⁺.An evaluation of the influence of different experimental parameters on mercury re^-emission efficiency was carried out. The experimental results indicate that flue gas Hg⁰ re^-emission across a wet FGD scrubber can be reduced by increasing the initial pH value, concentration of S(IV), or lowering the temperature. Under simulated wet FGD conditions, Hg²⁺ reduction efficiency decreased with the increasing concentration of F^- and Cl^-. The S(IV) induced Hg²⁺ reduction and Hg⁰ re^-emission mechanism is complex, the main pathways are through Hg·S(IV) complexes. Chloride slows re^-emissions dramatically through changing reaction mechanism.The last objective of this work is to investigate the Fenton's reagent oxidize metallic Hg to ehance the removal of Hg⁰. The experimental results indicate that iron^-based Fenton^-type additives gave much more promising results compared to Cu^-based Fenton^-like additives for Hg⁰ oxidation, Fe²⁺ solution was found to perform better than Fe³⁺ solution in the overall conversion processes. There is no indication that the presence of SO₂ contributed to the reduction of dissolved Hg²⁺ to Hg⁰. Solution pH was found to have a significant effect on the oxidation of Hg⁰ and a suitable solution pH window was found between 1.0 and 3.0 in this application. The present findings could be valuable for industrial application of characterizing and optimizing mercury control in wet FGD systems.