Study On Phase Equilibrium And Process Simulation In Acromatic Extraction With Sulfolane As Solvent

Acromatic extraction with sulfolane as selective solvent is an important process, which is often used in the modern acromatics units.The flowsheet of acromatic extraction is complicated and there are many factors to affect the stability of operations. It is very important to provide the equilibrium data of systems containing sulfolane and analyse the crucial factors of acromatic extraction by process simulation.In this study, VLE data for six binary systems containing acromatic(benzene, toluene, ethylbenzene, p-xylene, iso-propylbenzene, 1,2,4-trimethylbenzene) and sulfolane were measured at atmospheric pressure using Rose kettle. These experiment data were correlated by NRTL model and UNIQUAC model for activity coefficient. The binary parameters of these two models were provided.LLE data were measured for two binary systems containing sulfolane and cycloalkanes(1,3-dimethylcyclohexane and n-propylcyclohexane) in this study. These experiment data were correlated by NRTL model and UNIQUAC model using temperature-dependent parameters. The binary parameters of these two models were provided.Due to the diversity of systems containing sulfolane and the unreality and limitation of experimental determination, UNIFAC estimation model was used in order to obtain more equilibrium data for acromatic extraction systems. UNIFAC-Dortmund model was used and the experimental VLE data were regressed, binary parameters for three pairs of UNIFAC groups(CH2-TMS, ACH-TMS and ACCH2-TMS) were obtained. The VLE data of three binary systems containing acromatic(n-butylbenzene, 1,2-dimethyl-3-ethylbenzene and 1-methyl-3ethylbenzene) and sulfolane at 101.33KPa were estimated and the reliability of the UNIFAC-Dortmund methodwas tested. The estimation data were correlated by NRTL model and binary parameters were provided. LLE data for alkanes-sulfolane systems from literatures were used to test the reliability of UNIFAC-LLE model. It was found that this model with it's parameters already reported was not suitable for estimating LLE data for systems containing sulfolane in high temperature region. However, UNIFAC-Dortmund with regressed binary parameters using LLE data sets reported in literatures performed well in estimating LLE for alkanes-sulfolane systems. LLE data for four systems containing alkanes(iso-pentane, methyl-pentane, methyl-hexane and methyl-heptane) and sulfolane were estimated by the UNIFAC-Dortmund method. The estimation data were correlated by NRTL model and binary parameters were provided.Process simulation software-Aspen Plus with regressed parameters in this study was used to simulate the flowsheet in patent addressed by RIPP. The simulation results were consistent with the patent, and some crucial factors that would affect the stability of operations were analysed through the computer simulation.