Study On The Effect Of Water And Ash In Coal On The Co-refining Reaction Of Coal/Heavy Oil

China's low-rank coal resources are abundant,but the water and ash content in low-rank coal is too high.Excessive water and ash cannot be fully converted in coal liquefaction reaction,and it will also pollute the environment.Therefore,the dewatering and deashing treatment of low rank coal is essential for efficient use of coal resources and environmental protection.In this thesis,five kinds of raw coal with different moisture and ash were taken as the research object.The raw coal was dehydrated and delimated by thermal drying dehydration method and chemical deashing method respectively.Low field nuclear magnetic resonance,industrial analysis,FT-IR,XRD,SEM and other characterization methods were used to investigate the changes of coal structure before and after dewatering and deashing,and the stability of coal slurry prepared from raw coal with different moisture and ash content and its hydro-co-refining reaction were investigated.The change of properties,preliminary discussion on the effect of moisture and ash in coal on the co-refining reaction of coal/heavy oil.Studies have shown that there are four kinds of water in the coal,such as non-freezing water,adsorbed water,inter-particle water and free water.Most of the water is easy to remove,and a small part of non-freezing water and adsorbed water are more strongly combined with coal.It is not easy to remove.The organic matter structure of dehydrated coal is basically unchanged,but the proportion of pores in coal has increased.Coal contains inorganic minerals such as Ca CO₃,kaolin,iron oxides and sulfides,among which high-ash coal has a high content of non-catalyzed Si and Ca.After deashing treatment,most of the inorganic minerals in the coal are removed,and the organic carbonaceous structure in the coal is destroyed and the degree of condensation is reduced,and the proportion of pores in the coal is also increased.From the difference of viscosity and stability of coal-oil slurry prepared from raw coal and its dehydrated and deashed coal,respectively,it can be seen that at the same temperature,the viscosity of the coal-oil slurry prepared by dewatering coal and heavy oil is reduced,and the stability is somewhat Reduction of oil coal slurry prepared by deashing coal and heavy oil,the stability is improved to some extent.Under the same reaction conditions,the difference in reaction performance between feedstock coal and its dehydrated and delimed coal and heavy oil hydro-co-refining can be seen that the conversion rate and oil of dry ash-free coal for hydrorefining of dehydrated coal and heavy oil are known.The increase of the yield indicates that the excess water plays an inhibitory role in the liquefaction process;the conversion rate and oil yield of the dry ash-free coal by the high-ash coal and the heavy oil after the deashing treatment are gradually increased,indicating an excessive amount.The ash is inhibited in the liquefaction process;the conversion and oil yield of dry ash-free coal with low ash coal and heavy oil after deashing are slightly reduced,indicating that the proper amount of minerals in the coal liquefaction has a certain degree of catalysis.