Study On The Removal Of Chloride In The Combustion And Gasification Of High Chlorine Coal

In the process of coal combustion and gasification,chlorides in coal will undergo chemical conversion to generate HCl,which will not only severely corrode the gasifier,but also harm downstream equipment and catalysts after being released into the crude gas.Taking the gasifier of Xinjiang Guanghui new energy Co.,Ltd.as the research object,the law of chloride transfer and conversion in the process of combustion and gasification of high chlorine coal was investigated,and a special chlorine fixation agent suitable for high chlorine coal was developed in order to mitigate the chlorine corrosion of industrial gasifier.The chlorine content of coal samples from four production areas in Xinjiang was determined by high temperature combustion hydrolysis method.The chlorine content of coal sample in Jiangna mining area was 3052.42?g/g,and that in Baishihu No.1,No.2and No.3 mining areas were 326.62?g/g,138.95?g/g and 2171.50?g/g,respectively.The data of chlorine content show that the coal sample in Jiangna mining area was catagorized to high chlorine coal,the coal sample in Baishihu No.3 mining area was catagorized to medium chlorine coal,and both coal samples in Baishihu No.1 and No.2mining areas were classified to ultra-low chlorine coal.At the same time,the law of chlorine release in coal under different conditions was investigated.Identification of organic and inorganic chlorides in high chlorine coal indicates that the tetrachloroethylene and bromodichloromethane were two kinds of main organic chlorides and the Na Cl,KCl,Ca Cl₂and Mg Cl₂were four kinds of main inorganic chlorides in high chloride coal.The three-dimensional dimension and minimum cross-sectional diameter of tetrachloroethylene and bromodichloromethane were obtained by using the molecular model building software Gauss View 6,the quantum chemical calculation software Gaussin 16 and the quantum chemical wave function analysis software Multiwfn 3.6.The minimum cross-sectional diameters of the two organic chlorides were between 0.7 and 0.8 nm.According to the operating conditions in the gasification furnace,the thermodynamic analysis of the reaction of inorganic and organic chlorides to generate HCl in high chlorine coal was conducted.The change tendency of Gibbs free energy of each reaction of chloride to HCl was investigated.The results indicate that both inorganic and organic chlorides can be converted into the corrosive component HCl during the combustion and gasification of high chlorine coal.The suitable active components of chlorine fixation agent were selected by evaluating the chlorine fixation effeciency of Ca O,Ca CO₃,Ca(OH)₂,Ca(CH₃COO)₂and Sr CO₃.SEM,BET and XRD characterization of laboratory-made chlorine fixation agents were performed.The results showed that the chlorine fixation agent has porous structure,good crystal structure,uniform distribution of internal space and elements,it belongs to mesoporous materials with an average pore size of 10.8 nm and is conducive to the internal diffusion and reaction with active components of HCl.The effects of key factors such as calcination temperature,active component dosage,reaction temperature,vapor oxygen ratio and particle size of chlorine fixation agent on the chlorine fixation effeciency were investigated.In the range of investigation conditions,the lower the reaction temperature,the larger the vapor oxygen ratio and the smaller the particle size conduce to the better the chlorine fixation performance.