Industrial & Engineering Chemistry Research, Vol.39, No.6, 1614-1623, 2000
Extractive distillation solvent characterization and shortcut design procedure for methylcyclohexane-toluene mixtures
A preliminary solvent screening tool for two-column extractive distillation flowsheets is described whose results can be used to initialize process simulators. The tool uses shortcut approximations to extractive distillation that accurately predict the relative column performance of alternative solvents with rigorous simulations using the Aspen Plus process simulator. The activity coefficient ratio of each feed component in the presence of the solvent, the boiling point difference between the high boiler and the solvent, and an a priori heat integration criterion characterize potential solvents. It was found that staging requirements for the flowsheets could be approximated using 4 times the number of stages predicted using the Fenske equation when it was applied over each column section. Using these approximations resulted in a shortcut method for evaluating and comparing alternative solvents and solvent families, predicting the staging requirements and quickly determining the feasibility of completely heat integrating a flowsheet.