Fundamental Research on Integrated Heavy Oil Deep Stage Separation and Fluid Thermal Conversion(ISFTC) Process of Dagang VR

Author:Song Hai Peng

Supervisor:zhao suo qi xu zhi ming sun xue wen


Degree Year:2018





The high-efficiency processing and utilization of heavy oil is the focus of petroleum refining industry.Solvent deasphalting is simple and low energy consumption upgrading method to get DAO(deasphalted oil),which is of better quality and could be subjetced to secondary processing for higher economic value.However,the high softening point by-product DOA(deoiled asphalt),which possess worse quality would causes a difficulty to the processing and solvent recovery.Therefore,the process of integrated supercritical fluid extraction of heavy oil and fluid thermal conversion(ISFTC)for DOA was proposed.This thesis focuses on the technology fundamentals of this integrated process in regard to solvent select,effect evaluation of DAO fluid catalytic cracking(FCC)and influence of operating condition on thermal conversion liquid products,including the boiling curve distribution,general properties and molecular information.In addition,three different feedstocks were also compared to investigate the processing performance.Dagang vacuum residuum(DGVR)was selected as feedstock and n-butane,isobutane were selected as deasphalting solvent.The extraction conditions were set as temperature of 90120℃,pressure of 46 MPa and solvent ratio of 35(m/m).The supercritical fluid extraction performance of DGVR and the influence of operating conditions(temperature,pressure,solvent ratio and solvent type)on extraction product were systemically studied,including distribution and properties,such as density,viscosity,molecular weight,carbon residue and group composition of DAO and density,carbon residue and softening point of DOA.By comparing selectivity of the two extraction solvents,it turned out that isobutane DAO had a better fluid catalytic cracking(FCC)performance.FCC processing performance of isobutane DAO was studied on a fixed bed catalytic cracking unit with LDO-70 catalyst under typical FCC conditions.The relation between catalytic cracking product yields and properties of feedstock DAO were obtained,such as carbon residue,H/C atomic ratio,resins and asphaltenes contents.It was found that the catalytic cracking conversion rate was close to 90%when the yield of DAO was between 40%to 64%,,and the cracking product was mainly gasoline,the yield of light oil was close to 70%and the total liquid yield was up to 86%.For isobutene and n-butane DOA,which extraction yield is 3669 m%and 2752%respectively,the coking performance was evaluated at 520℃for 60 min.The effect of DOA yields and properties on coking product yield distribution was obtained.It was found that coking liquid product yield increases with increase of DOA recovery,whereas coking gas and coke yield would be decrease,notably,the yield of diesel and coking gas oil(CGO)in liquid product,thus CGO(>350℃)increased significantly.The diesel and CGO yields were both much higher than gasoline.On the other hand,under the same coking conditions,the coke yield of isobutane DOA is less than n-butane DOA,and the yields of liquid product with its distillates were higher.It was showed that isobutane as solvent was also better to thermal conversion.In addition,the effect of coking conditions on the DOA coking performance was investigated for reaction conditions selection of thermal conversion unit in ISFTC.The ISFTC process study for DGVR was carried out on a continuous ISFTC apparatus.The influence of separation unit on the fluid thermal conversion product yields and its properties were obtained.The effect of extraction temperature on fluid thermal conversion products was found to be severer than other extraction conditions,or it should be called the controlling factor.Meanwhile,the effect of fluid thermal conversion conditions,including temperature,fluidized medium flow rate and heat carrier mass rate,on thermal conversion product yields and properties of liquid product were investigated.Moreover,the molecular composition characteristics of nitrogen compounds of fluid thermal conversion liquid product were analyzed by Fourier Transform Ion Cyclotron Resonance Mass Spectrometer(FT-ICR MS)and 1H,13C Nuclear Magnetic Resonance(1H,13C-NMR),and Gas Chromatography and Mass Spectrometry was applied in the hydrocarbon compositions analysis of fluid thermal conversion gasoline,diesel and CGO.In comparison to n-butane,the yields of fluid thermal conversion liquid product and CGO were higher when isobutane was applied as solvent,and the yields of gasoline,diesel and coke were less.The carbon residue,density,molecular weight,sulfur and nitrogen contents and aromatic ring structure condensation degree of fluid thermal conversion liquid product were all higher.Under extraction temperature of 100℃,pressure of 5 MPa,solvent ratio of 4(m/m),thermal conversion temperature of 520℃,fluidized medium flow rate of 4g/min and heat carrier mass ratio of 1:3,Dagang vacuum residue,Huajin Brazil vacuum residue and Daqing oil slurry were subjected to ISFTC process to compare the relation between material property and processing performance.It was found that there is a certain relationship between the content and type of DOA aromatics and the properties of fluid thermal conversion liquid product.Comparing to DGVR delayed coking,the yield of total liquid product ISFTC and light oil increased by 7 and 10 percent respectively.Comparing to DGVR fluidized thermal conversion,the total liquid yield of ISFTC increased by 14 percent.