Gaseous Mercury Adsorption From Simulated Flue Gas

Pollutants produced by coal combustion are major sources of air pollution. Mercury emissions from coal-fired flue gas has resulted in direct or potential hazards on human health. A great of concern has been given to mercury pollution from flue gas. Because of the low melting point, high equilibrium vapor pressure and low water solubility, the elemental mercury is difficult to remove. Therefore, effective removal elemental mercury from flue gas has important scientific significance and application value. The purpose of this study is to develop efficient adsorbens for mercury removal from simulated flue gas. The contents of the job are listed as follows:The abilities of different types of adsorbents had been investigated according to adsorption capacity of adsorbents. The effect of the gas flow rate, adsorption temperature, inlet concentration on the adsorption breakthrough curve,adsorption capacity were investigated. Results showed that activated carbon fiber has a good adsorption property of mercury. The adsorption capacity of activated carbon fiber decreased with the increase of the feed gas flow rate and adsorption temperature, increased with the increase of the inlet mercury concentration. The presence of water vapor could improve the adsorption capacity. The adsorption capacity of the heat-treated activated carbon fiber decreases significantly.Then, activated carbon fibers were modified through four methods:modified by wet oxidation, silver modification, manganese modification, chlorine modification. Adsorption performances of all kinds of modified activated carbon fibers were evaluated. The results showed that wet oxidation, silver modification, chlorine modified activated carbon fiber can improve the adsorption capacity of mercury. The adsorption capacity of the activated carbon fibers modified by KMnO4 and MnO2 had increased because of the strong chemical adsorptionduring the adsorption process. Mn (NO3)2 impregnation reduces the adsorption capacity of activated carbon fiber.Lastly, the best adsorption capacity of the sorbent was selected from the modified activated carbon fibers. The effect of the different feedstock, the content of impregnation agents, the adsorption temperature on the adsorption breakthrough curve,adsorption capacity were investigated. The results showed that the presence of CO2 mad against removal of mercury. There was competition adsorption between the mercury and CO2. The adsorption capacity of the activated carbon fibers modified by FeCl3 first increased and then decreased with the loadings of the FeCl3.The best loading content was 30%. The adsorption temperature had a great impact on the adsorption capacity. The adsorption capacity of the activated carbon fibers modified by FeCl3 decreased with the increase of the adsorption temperature.