| With the rapid development of China’s economy,pollutant emission has seriously affected human health.The energy structure in our country is based on coal.Sulfur element in coal causes the existence of sulfur dioxide in flue gas.How to reduce sulfur dioxide emission has become an important task of environmental protection.There are many kinds of technologies to remove sulfur dioxide from flue gas,but the secondary pollution of desulfurization products is a common problem in the developed technologies.Chemical-looping desulfurization technology has the characteristics of high desulfurization efficiency,simple process,renewable desulphurizer and no waste,etc.The most important part of this technology is the selection and preparation of desulfurizer.Suitable desulfurizer can achieve a complete cycle while maintaining high desulfurization efficiency.(1)Analyzed the feasibility of removing sulfur dioxide from flue gas with manganese oxide by using HSC Chmistry software,based on the technology of removing hydrogen sulfide from gas at high temperature with Mn-based desulfurizer.The results show that tetravalent manganese oxide and trivalent manganese oxide have the theoretical feasibility of chemical-looping desulfurization.A series of experiment will be designed to verify this result and study their characteristics(2)Manganese-based desulfurizer was prepared by impregnation method.The effect of preparation conditions on the preparation results was investigated.Come to the conclusion that the best inert carrier is diatomite,the best dipping time is 2 h,the best active component quality score is 40%,and the best calcining time is 5 h.The best produce temperature of manganese dioxide is 350℃,and the best produce temperature of manganese sesquioxide is 500℃.The mechanism of the sulfuration reaction of manganese-based desulfurizer was studied by various characterization methods.(3)A fixed-bed vulcanization experiment was designed to investigate the influence of operating parameters on the desulfurization effect of manganese-based desulfurizer.Quadrivalence Mn-based desulfurizer optimum reaction conditions are:the temperature is 300℃,the space velocity is 500 h-1,the inlet SO2 concentration is 0.5 ‰,with these conditions,the time of the reaction efficiency over 90%is 6 h.Trivalent Mn-base desulfurizer optimum reaction conditions are:the temperature is 300℃,the space velocity is 500 h-1,the inlet SO2 concentration is 0.5 ‰,the inlet concentration of O2 is 6%,with these conditions,the time of the reaction efficiency over 90%is 20min.(4)The desulfurization products were regenerated by pyrolysis.Desulfurizer’s regeneration temperature and the performance of the desulfurization was studied,the conclusion is that,the best temperature of regeneration is 750℃,the renewable products is manganese sesquioxide.After five cycles,the regeneration rate of desulfurizer is above 97%.After two cycles,the desulfurizer’s desulfurization time can reach 90%of the fresh desulfurizer.After five cycles,the desulfurizer’s desulfurization time is only 50%of the fresh desulfurizer.The main reason for the decrease of desulfurization effect of regenerative desulfurizer is the decrease of mechanical strength at high temperature. |
