The Study On The Extractive Distillation With Salt Of Isopropanol-Water System

In this paper dynamic batch extractive distillation of isopropanol-water system was studied by theoretical analysis and experiment. To obtain high purity isopropanol, water should be removed as more as possible, however, isopropanol and water forming azeotropic mixture, it would consume plenty of solvent by general extractive distillation, but adding salt can overcome this defect.With a single random packing column, batch extractive distillation method was applied to the separation of isopropanol-water system, this paper we selected the optimum operating conditions of the technological operation, such as reflux rate, calefaction pressure, the speed of extractive agent etc.And also investigated the different effect with glycol and K2SO4,KAC,ZnCl2on distillation, it was proved that the purity of isopropanol can reach about98.9%.The result shows the product can meet the industry needs.The Gibbs free energy of transfer of three kinds of salt in mixtures where salting-out phenomenon occurs at was calculated with the solvation model and scaled particle theory. The results are compared with salt effect on Vapor-Liquid Equilibrium (VLE).In most cases, salt effect on VLE is increasing with the increasing of the Gibbs free energy of transfer of salt in systems containing water. The results show that salt effect can be explained by the theory of the Gibbs free energy of transfer.Therefore, the Gibbs free energy of transfer can be used as a guide in salt selection in separation process adding salt.The simulation based on equilibrium model was applied in the extractive distillation with salt, the effect of reflux ratio and solvent ratio of product were investigated, and concentration distribution for vapor and liquid in the column were simulated. The study on the whole process of extractive distillation with salt was carried out in laboratory. The experiment results proved that laboratory data was consistent with theoretical derivation.