Preliminary Design And Type Selection Of Pilot Test In Industrial Flue Gas Desulfurization By Red Mud

A large amount of SO2mostly from thermal power plant causes the environment seriously polluted. At the same time, the more serious threat to the environment brought by alumina red mud is due to its alkaline and large amount. This research comes from the Sub-project of2010Henan Major Commonweal Research Project (No.101100910200):"Technological Research of Industrial Flue Gas Desulfurization (FGD) by Alumina Red Mud", which aims at exploring a new desulfurization process that brings about waste utilization.The grain size, microstructure and mineral composition of red mud (from Henan Branch of China Aluminum Co.) were determined in this research. The results showed that the red mud used in wet FGD process was feasible and efficient, the desulfurization products can be used as additives in silicon-calcium fertilizer. The laboratory was built in Zhengzhou Xinli Electric Power Company, a small glass absorber device whose size is1700×60mm was designed and built on site. Moreover, the appropriate equipments such as slurry pump and induced draft fan were type selected and installed. The optimum conditions were obtained by orthogonal test as follows:liquid-solid ratio7/1(g/g), flue gas flow3.6m3/h, liquid-gas ratio15/1(L/m3), the temperature of flue gas20℃. The results were obtained that it was time to add fresh slurry when the red mud slurry’s pH value was5.9, and the efficiency of desulfurization could be kept more than95%, adding1/8of the total volume of red mud slurry every time could make full use of red mud. The order of influencing factors was:liquid-gas ratio> liquid-solid ratio> flue gas flow> the temperature of flue gas.According to Principles of Chemical Engineering, Desulfurization Engineering Technology and Equipment and corresponding national standards, the flue gas flow was set as6000m3/h, the desulfurization efficiency was set as95%. Then the diameter of the flue gas duct could be calculated as420mm, and the size of the absorber was5500×1500mm, and its material was carbon steel lined with resin. The type of induced draft fan and centrifugal pump were selected as4-72No.4A and IS80-50-200by calculating. The mixer, the spray layer, the oxidation fan, the mist eliminator and the process water systems were designed and selected. The consumption of red mud was35kg/h by calculating, the volume of red mud silo and fresh slurry tank were1m3and2.5m3. The desulfurization devices should be treated anti-corrosion, the flowmeter, the pH meter, the densitometer, the level gauge, the flue gas analyzer and other inspection instruments were also type-selected. The system was controlled automatically to ensure the process and desulfurization equipment operated safely and realiable.The experimental results and the design of pilot experiment device provide a theoretical basis and data support for the industrialization promotion of red mud FGD process, which can remove SO2in flue gas efficiently and make make use of the red mud resource.