Canadian Oil Sands Bitumen Vacuum Residue Stage Separation Based On Countercurrent Extraction

The deep stage separation process was a kind of solvent deasphalting technology,which developed by key laboratory of heavy oil independently.The deep stage separation process utilized the phenomenon that the properties of supercritical fluid solvent varies significantly with the temperature and pressure of the extraction system.Compared to the traditional route,the deep stage separation process not only inherited the advantages of high yield and low operating cost,but also greatly reduced the energy consumption of solvent recovery.In this work,Canadian oil sands bitumen residuum was used as raw material,pentane as solvent.Solvent deasphalting experiments were carried out in a self-designed countercurrent extraction column.The influence of operating conditions such as flow pattern,temperature,pressure and the ratio of solvent to feed on the yield and quality of DAO were systematically studied.The results showed that,under the temperature of 160 °C and the pressure of 5 MPa,the yield and properties of the deasphalted oil obtained by countercurrent extraction with the S/O of 2.5 were similar to that obtained by traditional separation with S/O of 4.It revealed that the countercurrent extraction significantly reduced the S/O and solvent recovery energy consumption.The optimal operating conditions were selected as below: the pressure at 5 MPa,the top temperature at 170 °C,bottom temperature at 150 °C,S/O ratio at 2.5,M/A solvent ratio at 2.25:0.25.Under these conditions,the deasphalted oil yield was 64.20 wt%,the residual carbon removal rate was 47.90 wt%,nickel removal rate was 76.95 wt%,vanadium removal rate was 79.51 wt%,sulfur removal rate was 47.12 wt%,and nitrogen removal rate was 55.81 wt%.The experiments were simulated by Aspen Plus process simulation software,the pseudo components was obtained by calculation based on the simulated distillation data of feed,PSRK model was chosen as the thermodynamic method,the simulation results showed that the calculated values fitted well with the experimental data,the maximum error between simulated value and experimental value of yield was less than 6.1 wt%.According to simulations,S/O ratio was the key influencing factor of the energy consumption level.The relationships between yield and energy consumption under the S/O ratio of 2.5,3.5,5,8 were studied respectively,which can be helpful in economic analysis in practical production process.