Desolidation Of FCC Slurry And Coal Tar And Their Ultilization With High-value Addition

Both the slurry from fluid catalytic cracking(FCC)process and coal tar are high-boiling-point by-products from petroleum processing and coal-based coke making.They contain a lot of condensed aromatic structures,giving promising potentials as feedstocks for producing needle coke and other high-value-added chemicals.However,a priority of these potentials is that the solids in both FCC slurry and coal tar must be efficiently removed.Therefore,by investigating desolidation of these two thermolysis heavy oils and utilization of these solid-free thermolysis heavy oils,this study aims to form a fundamental basis for developing technologies in high-value-added utilization of these thermolysis heavy oils.Firstly,electrostatic separation method was applied to remove the solid particles from an FCC slurry.Based on the electrostatic separation apparatus established by ourselves,impacts of feedstock properties,operation conditions and apparatus materials on purification of the FCC slurry were investigated.Multistage electrostatic separation process was also investigated primarily.Results show that in the range of experimental temperatures,all the properties including viscosity,conductivity and dielectric constant of the FCC slurry meet the demand of the electrostatic separation.The constitution of the solid particles mainly concludes catalyst fines,cokes and some Sb metal.The conductivity and dielectric constant of the solid particles are higher than that of FCC slurry,and the conductivity and dielectric constant of inorganic substance in the FCC slurry are higher than the organic cokes.The materials of the apparatus have a big impact on the separation effect.Results show that the effect of copper electrode is better than iron electrode.At the experimental conditions,big-sized electrode and small-sized fillings have the better effect.The optimized operation conditions are 12-13 k V of voltage,20-25 min of time and 130-150 oC of temperature.Multistage electrostatic separation process can obviously improve the separation effect of catalytic fines,however,this process has little separation effect of cokes.Then,assistant sedimentation method coupled with centrifugation was applied to remove the solid particles from the coal tar.In this paper,the influences of types and dosage of the assistant,and experimental conditions on coal tar purification were investigated.The coal tar purification routing was designed primarily.Results show that the solid particles consist of organics with high degree of condensation.The crystal structure of the solid particles is similar to carbon black.Moreover,the solid particles may contain alcoholichydroxyl,phenolic hydroxyl group and condensed ring aromatic structures based on the analysis of infrared spectrum.The better diluting agent optimized among several diluting agents is the mixture of light oil and wash oil(1:1 of mass ratio).And the optimized dosage of the diluting agent is 30% of the feedstocks.The optimized binder is the mixture of wash oil and paraffin(0.5:1 of mass ratio),and the optimized dosage is also 30% of the feedstocks.Addition of organic alcohol B can improve the purification effect of coal tar by improving the surface properties of the solid particles.Moreover,1?g g-1 flocculating agent F can also improve the purification effect.For the experimental conditions,the optimized temperature is about 75 oC and the optimized sedimentation time is about 24 h.In addition,centrifugal separation method was proved to have a good effect on purification of the smaller solid particles,with optimized centrifugation force being 4000 g for 5 min.The purified coal tar contained solids content lower than 0.1%,giving a purification efficiency of 98%.The coal tar purification routing which was designed primarily can be applicable to the practical operation.Finally,take the coal tar as example,for the novel utilization of pyolysis heavy oil with high-value-addition,besides being as the feedstocks of needle coke,the hydrogenation products can be used as hydrogen donating agents to improve the upgrading effect of heavy oils.Thus,in this paper,the distillates of the coal tar were firstly hydrogenated.Then,impacts of the hydrogenated distillates on the upgrading effect of Valenzuela vacuum residue and the properties of the delayed coking products were investigated.Results show that product(i.e.hydrogen storage agent C)of distillate c hydrogenated at the conditions of 350 oC,7 MPa and 60 min has better hydrogen storage ability which can be used as hydrogen donating agent in the later experiments.During the upgrading of Valenzuela vacuum residue,optimized upgrading conditions are 5 % hydrogen storage agent C,400 oC and 40 min.Compared with the blank experiments,the coke induction period of the products increases 9 min,the viscosity is lower and the stability is better.The optimized coking conditions for Valenzuela vacuum residue are 500 oC,1.5 MPa and 2 h.And at the same conditions,coke produced by distillate c has good optical configuration and temperate yield.Distillate c has the potentiality to produce needle coke.During the mixed coking of coal tar distillates and Valenzuela vacuum residue,hydrogen storage agent C has better effect on the coke quality than distillate c.