Study On Coke Formation Mechanism Of Aromatics Rich Bitumen By Fractional Carbonization Reaction

With the development of science and technology,humans being attach great importance to environmental problems,the development of new energy sources and the continuous exploitation of oil and gas resources,traditional fossil energy is declining sharply and will gradually withdraw from the stage of fuel oil in the future.At present,the Major refineries in China are promoting the construction of equipment other than fuel oil,such as polyethylene,polypropylene,synthetic rubber,delayed coking equipment,etc.How to improve the utilization rate of traditional fossil energy such as coal,oil,etc.,has become an important subject for domestic pursuit.As an important product of delayed coking,needle coke has the advantages of low thermal expansion coefficient,high density,and low heteroatom content.The application of needle coke in the field of electric furnace steelmaking can effectively solve the demand of high power,ultra-high power electrode resistivity,low mechanical strength in the field.China has been exploring the raw materials and production process of high-quality needle coke.Compared with the international perspective,the research of China’s needle coke still lags far behind that of other developed countries,which cannot produce high-quality needle coke.Therefore,the research on raw materials and production process to improve the structure and performance of needle coke has become a breakthrough point for many domestic scholars.This paper is based on MLCT and HCTO-2-2 as raw materials,in order to adjust and optimize the aromatics content in MLCT,the aromatics enrichment was firstly carried out in MLCT.After analyzing the raw materials,the needle coke was prepared by one-step condensation polymerization.The effects of temperature and reaction pressure on the structural properties of needle coke under constant temperature were investigated,the structural properties of needle coke under the condition of constant pressure difference and of fractional carbonization reaction,in order to further increase the utilization rate of raw materials,biomass additives were selected to carry out the co-carbonization reaction of raw materials to get the carbonization product needle coke,and finally the product coke was calcined at high temperature to get the cooked coke.Through the characterization of the coking structure of the carbonization products of the two raw materials,it is found that the temperature is the most important factor,and the appropriate temperature plays a decisive role in the formation and development of the Mesophase.The reaction pressure Mainly affects the size and orientation of the optical structure.The results show that the carbonization products of coal series raw material MLCT have a large area of inset structure with the increase of temperature,and the optimal carbonization reaction condition is 450℃-4.0MPa/6h-2.5MPa/2h,while the structure of petroleum series raw material HCTO-2-2 is the best under the carbonization reaction condition of 460℃-4.0MPa/6h-2.5MPa/2h.With the increase of temperature,the orientation of the products shows a trend of increasing firstly and then decreasing.On the basis of obtaining the optimum carbonization reaction conditions,the formation law of the optical structure of needle coke under the carbonization reaction conditions was studied by changing the reaction pressure and carbonization reaction level after determining the reaction temperature.Results show the optical structure of coal-baaed needle coke becomes better with the pressure increasing,emerged from mosaic structure to a large area optical structure and a trend of orientation degree increase,petroleum-baaed needle coke also from small area of optical structure into a large area optical structure,the carbonization products of the two kinds of raw materials showed better needle-shaped structure at the temperature of4.5MPa/6h-4.0MPa/2h;With the increase of carbonization stage,initial carbonization pressure and carbonization time,the suitable viscosity condition is obtained.Under this condition,the mesophase is fully developed and accompanied by supplementary air flow,which is conducive to the formation of wide area streamline fiber structure,which is conducive to the formation of wide area streamline fiber structure.In order to increase the utilization rate of raw materials,choosing additive and raw material for biomass carbonization reaction,results showed that the biomass add will make the mosaic structure of needle coke appear more,but at the time of adding amount of 10%,system in a suitable viscosity,mesophase spheres can get a better development,the optical structure and orientation degree are better.After calcination,the needle coke can effectively remove its own heteroatoms,improve the graphitization degree,and promote the development of needle structure.