Study On Fast Pyrolysis Process Of Poor Quality Heavy Oil

With the increasing depletion of conventional crude oil,the world’s supply of crude oil shows a trend of heavy and low quality,refinery plants process more and more heavy crude oil which accounts for the majority of proportion.Processing of heavy crude oil in refinery will produce a lot of worse quality residual oil,and traditional treatment methods always have disadvantages,thus the modification process of fast pyrolysis of heavy oil was put forward in this paper for the sake of light oil which can provide high quality raw materials for the second clean processing.The Changqing vacuum residue used as raw material in a fixed fluidized bed reactor.The reactive results of the quartz sand,FCC catalyst,activated alumina and magnesia alumina spinel,which used as thermal catalytic carrier of heavy oil pyrolysis process respectively,was investigated..Experimental results show that the quartz sand mainly provides heavy oil thermal conversion reaction sites,and have almost no catalytic activity,so the inferior heavy oil conversion rate is low.The activity of the FCC catalyst is high,the gas and coke content in the product are high,so the liquid yield is low,at only 40%.Products of activated alumina and magnesia alumina spinel contain high proportion of middle distillate diesel and VGO,which can be used as follow-up FCC or hydrocracking feedstock oils.The spinel is desirable carrier for the fast pyrolysis of inferior heavy oil modified catalyst.The spinel used as inferior heavy oil catalytic heat carrier.The effects of reaction temperature,catalyst to oil ratio,the weight space velocity and water oil ratio operation parameters of heavy oil pyrolysis was investigated.Experimental results show that:with high liquid yield and higher heavy oil conversion rate as the target,the optimal operation conditions were founded,reaction temperature at 500℃,the ratio of catalyst to oil at 6,weight airspeed at20h^-1,water oil ratio at 0.6,liquid yield at 82.31%and transformation rate at 89.54%.In optimal operating conditions of liquid products,carbon residue removal rate is more than 80%,almost all asphaltene was removed with desulfurization rate at 33.33%and removal of nitrogen at 41.5%.The quality of inferior heavy oil is improved,which meet the requirements of catalytic cracking and catalytic hydrogenation feeds or other secondary processing raw materials.With the composition of raw material becoming weight,viscosity become larger,part of the heavy oil molecules clog pores,difficult to spread into the pores of the catalyst with an acidic internal contact center transformation,which cleaves performance deterioration,manifested in dry gas and coke yield increase,while liquid yield and conversion rate.