Study On Flue Gas Desulfurization By Adsorption Method

Air pollution is mainly smoke pollution in China. SO2 produced by snioke from burning coal made air quality worse and acid rain more serious. To control SO2 pollution has became an urgent demand. It's an efficient way to eliminate SO2 by adsorption method.The influence of S02 inlet concentration, gas space velocity, adsorption temperature and O2 and H2O in flue gas has been systematically studied by using activated carbon as adsorbent. The adsorption capacity of activated carbon modified in different conditions and of some industrial solid wastes has been tested. At the same time, the mechanisms of the oxidation of SO2 over activated carbon surface have been analyzed, and fixed bed adsorption model has been set up.The result indicates that adsorption capacity was lower in the condition of higher SO2 inlet concentration and higher- gas space velocity, higher temperature was good for adsorption under 60 , but lower temperature was good over 60 , so adsorption temperature should be controlled at about 60 . Above all, the amount of S02 adsorbed over activated carbon could be enhanced by O2 and H2O. The increase of the amount of SO2 came from the amount of chemically bonded S02. SO2 remove capacity of activated carbon modified by potassium iodide, copper sulphate and nitric acid increased by 116%, 25%-and 16.7% over that of activated carbon unmodified. Steel wastes, coal cinder and alkali wastes could all be used to eliminate S02 from flue gas. Wetted steel wastes have higher activity than dry steel wastes. Alkali wastes can't be used as absorbent lonely by dry method. The mixture of alkali wastes and steel wastes has higher S02 eliminate efficiency than steel wastes have. As a result, selecting industrial wastes according to actual conditions can decrease the cost of flue gas desulfurization.The process of the catalytic oxidation of SO2 over activated carbon surface can be divided into three stages. The first stage is a constant rate process; the second stage is a decelerate process and the third stage is a constant rate process too. The rate at the third stage was six to ten percent to that at the first stage. The reason of reaction rate decreasing at the second stage is that sulfuric acid having stored in activated carbon pores. The reaction of oxidation of SO2 carries out over the surface of micropores, the macropores doesn't take part in the reaction. Adsorption takes place in adsorption belt in fixed bed. Supposing adsorption belt moves at a suppositional rate, the adsorption model equation in fixed bed can be set up through material calculation.NOX can be absorbed by activated carbon fiber. Adsorption capacity was affected byNOx inlet concentration, bed temperature, gas space velocity and gas humidity. The relationship among the lost pressure, the height and the space velocity of activated carbon could be described by equation: AP=37.8uL. SO2 remove capacity of activated carbon was hardly decreased after being regenerated by water.