煤高温热解过程中氯的释放特性研究OA

[Purposes]As a by-product of coking enterprises in China,crude benzene commonly exhibits fluctuations and exceedances in chlorine content.The characteristics of coal significantly im-pact the migration and transformation behavior of chlorine.[Methods]On the basis of the structural characteristics of coal and the distributions of chlorine forms,release behavior of chlorine during cok-ing coal pyrolysis was analyzed.The effects of secondary reaction temperature and residence time of volatile on the chlorine release process were also investigated.[Results]The results indicate that chlo-rine in organic forms in coal is released more readily.Coal samples with higher organic chlorine con-tent have more complete chlorine release under the same pyrolysis conditions.The chlorine content of pyrolysis gas and tar from Liulin coal is 44.20%and 53.67%,respectively(with a chlorine release rate of 97.87%).This is because the organic chlorine in coal is primarily bound to the coal structure via co-valent bonds and/or coordinations with alkaline and oxygen-containing functional groups.It is there-fore easily decomposed and converted into HCl or organic chlorides.However,the chlorine release rate for Inner Mongolian coal is only 85.01%,which is due to the presence of metallic components,such as calcium and magnesium.These metallic components can react with HCl to form relatively sta-ble inorganic chlorides.Compared with residence time,the secondary reaction temperature of volatiles has a more significant impact on chlorine release.Macromolecular compounds(e.g.,C13H19Cl,C20H12Cl2)undergo cleavage to form chlorine-containing free radicals.Then,they are converted into HCl and lower-carbon-number chlorinated substances(e.g.,C2H2Cl2O,C2H2Cl4)after combining with hydrogen-rich free radicals.There is interactive migration behaviour between these two forms of organic chloride and HCl.