Study On Simultaneous Removal Of Multi Pollutant In MCFB Flue Gas Cleaning System

SOx, NOx, and Hg are main pollutant of coal fired flue gas, and do harm to the environment. It is the hotspot and the great challenge that how to develop the flue gas clean technology from single pollutant control to multi pollutant control. This thesis is focus on multi pollutant removal of MCFB (Multi humidification stage and multi pollutant control Circulating Fluid Bed).In this thesis, effects of water and additive content on microscopic structure of composite calcium based absorbent are researched. It shows that:when H2O/Ca mole ratio is below 2.0, the conversion and particle size of product increase with the H2O/Ca up, and the specific area of product is largest while H2O/Ca reaches 2.0. Oxidizing additive is positive to improve microscope structure of the product, and the area increases with oxidizing additive content up. Hygroscopic additive has no positive effect apparently. In normal temperature reaction, conversion percent is bigger with higher water temperature,and the specific area is biggest at 50℃. Within low water content, conversion and specific area decrease with the reactant particle size increase, and it does not turn at H2O/Ca 2.0.NO, SO2, Hg removal experiments has done on laboratory scale experimental bench. It shows that oxidizing additive is in favor of increase NO removal, and the de-NOx efficiency rises with its content up. Particle moisture helps composite calcium-based sorbents for the removal of NO.Oxidizing additive is also in favor of increase Hg0 removal, and the de-Hg0 efficiency rise with its content up. Higher Hg0 content in flue gas, bigger specific area of Ca based absorbent, and lower temperature could realize high de-Hg0 efficiency. Mathematic model is built to research multi pollutant removal. The model results show when absorbent/Hg0 is constant, the Hg0 removal quantity is bigger with Hg0 content in flue gas increasing. At low temperature, the Hg0 removal quantity is big. Results of experiment and mathematic model are uniform.Based on research results above, MCFB pollutant removal flue gas cleaning technology is found for actual application, including multi stages humidification, multi hige-activity Ca based absorbent recipe etc. It is fit for removing SO2, NOx, and Hg0 etc pollutant from coal fired power plant and municipal waste incineration boiler flue gas. The test results by environmental protection department show that the MCFB flue gas cleaning system has high removal efficiency to SO2, NOx, and Hg0. The de-SO2 efficiency is 98%, de-NOx is 33.5%, and the total Hg0 removal efficiency could reach 73.1%.