Basic Characteristics Of Oil Extraction From Northern Shaanxi Oil Rich Coal Pyrolysis And Purification Mechanism Of Coal Tar

Shaanxi is the main coal producing area in China,which is rich in coal resources,especially the low metamorphic bituminous coal in Northern Shaanxi,with high tar yield,which is a typical oil-rich coal.It is of great significance to plan this resource according to local conditions and study the clean and efficient utilization of coal to alleviate China’s energy dependence on foreign countries.This paper analyzes the geology,geographical structure and coal seam evolution process of Northern Shaanxi coal mining area,analyzes the coal quality of Northern Shaanxi oil-rich coal,and clarifies its metamorphic degree and oil-rich genetic law.Taking Shanbei oil-rich coal as the research object,the effects of internal and external factors(such as origin,particle size,temperature,heating rate,pressure,catalyst,etc.)on oil yield of oil-rich coal pyrolysis were revealed,the distribution of coal tar components was analyzed,the mechanism of oil production from oil rich coal is elucidated from the aspects of macromolecular structure,chemical bond and functional group of coal.In view of the high dust content of coal tar at present,which leads to the low direct utilization rate,the quinoline insoluble(QI)and other impurities in coal tar were removed by catalytic polycondensation,lewis acid AlCl3 and CuCl2 were used as catalysts to increase the rate of polycondensation,using QI and other impurities in coal tar as nucleating agent,a kind of high performance carbon material precursor,namely mesophase carbon microspheres(MCMBs),was prepared to further improve the quality of coal tar and realize the clean and efficient utilization of coal tar.The results show that:(1)The oil-rich coal in Northern Shaanxi belongs to bituminous coal with ultra-low sulfur,low middle ash and medium high volatile;clay mineral is the main mineral type in coal;its metamorphic degree is low,so it is suitable for processing and conversion to produce coal tar and gas.(2)The structure and pyrolysis characteristics of oil-rich coal were studied.The results showed that:The oil production rate of oil rich coal in zhangjiamao mining area is the highest;The results show that the optimal particle size range of oil production from oil rich coal pyrolysis is 0.8～2mm,and the tar yield is 13.19%;The optimum temperature for oil production of oil rich coal is 550℃,and the tar yield is 13.19%;The optimal pyrolysis heating rate of rich oil coal is 60℃/min,and the tar yield is 12.98%;There is a negative correlation between pressure and oil yield,and high pressure is not conducive to tar production;The co-pyrolysis of foam metal catalyst can improve tar yield and quality.(3)The purification of coal tar by catalytic condensation.The results showed that:①After using AlCl3 and CuCl2 to purify coal tar,QI content in coal tar decreased,light fraction increased,and purification effect of AlCl3 was better;Time,catalyst and temperature have significant effects on QI removal rate,and time>catalyst>temperature;When AlCl3 and CuCl2 catalysts were used,more MCMBs were collected,and the collection efficiency of AlCl3 was higher;The catalyst and time had significant effect on the yield of MCMBs,and catalyst>temperature.