| Mercury emissions from coal-fired power plants as a large emission source to the atmosphere, is recognized the direct and potential risk to both human health and environment. The researches on the methods of mercury control from coal combustion are just carried out in the world. The sifting of effective adsorbents and the researches on the mechanism of mercury speciation transformation and mercury control are very weak too. Therefore it should be done urgently that carrying out the studies on mercury pollution, finding out the effective adsorbents and studying the mechanism of mercury speciation transformation and relevant methods of mercury control. It is very important for improving combustion quality and reducing the environment pollution.A bench-scale experimental is conducted to study effect of flue gas composition on the speciation distribution of mercury in simulated flue gas streams. The test method used here for mercury speciation was the Ontario Hydro Method. The speciation distribution of mercury in different coal-fired flue gas systems including or excluding HC1, different concentration of O2, different concentration of HC1, different temperature at reactor's exit, different concentration of Hg was studied in typical constituent flue gas systems. The conclusions reached were as follows: In coal-fired flue gas systems without HC1, the conversion ratio of Hg2+ to total Hg increases at low temperature and decreases at higher reaction temperature; In the coal-fired flue gas systems containing HC1, the conversion ratio of Hg2+ to total Hg increase with rise of reaction temperature; higher concentration of NO and O2 can enhance oxidation of Hg; the conversion decreases with increase of SO2 concentration, higher temperature at reactor's exit can increase the conversion ratio of Hg2+ to total Hg; the conversion ratio of Hg2+ to total Hg decreases with increase of Hg concentration.A kinetic model was developed to predict mercury speciation transformation based on mercury reaction characteristics as determined in mercury speciation transformation tests atdifferent conditions. The kinetic equation is: ; reaction rate is:k = 0.029858exp(-12787.54/RT). The simulation results indicated that the model is capable ofdescribing the test data. It also showed that the reaction temperature, contact time, HC1 inlet content, influenced the mercury speciation transformation.The modification of adsorbents was studied , then selects out effective adsorbents through the experiment on the experimental set-up which can simulate flue gas conditions in the power plant. The research mainly contains three jobs: Firstly, referring to many literatures and the methods of mercury removal in the industry of refining mercury, the experimental modification of adsorbents is made, which includes the reactive MnO2-impregnated adsorbents, the FeCl3-impregnated adsorbents, the sulfur-impregnated adsorbents at various temperatures, etc. Secondly, the preliminary selection of adsorbents is carried out on a fixed bed. The primary adsorbents and modified adsorbents are tested at the constant temperature. The mechanisms andrate of elemental mercury (Hg0) capture by activated carbons and some other modified chemically sorbents have been studied using a bench-scale fixed-bed apparatus. We have screened out some efficient sorbents such as activated carbons were impregnated with MnO2, FeCl3 and sulfur at 600癈, zeolite were impregnated with MnO2, roseite were impregnated with MnO2, FeCl3, and bentonite were impregnated with MnO2. The effects of flue gas composition, inlet mercury concentration, adsorption temperature and ratio of C/Hg were investigated to determine the abilities to remove mercury in simulated flue gas streams.The emission study for mercury was conducted at a 6 MW stone-coal-fired plant for the combustion of a coal with mercury concentration of 0.1209mg/kg. The power plant equipped with a cold-side electrostatic precipitator. During full load operation of the boilers samples of the input and output stream such as coal, coal ash, ESP ash and...
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