Comparison of energy consumption of two-column configuration and three-column configuration in the extractive distillation process for high purity refinement of isopropyl alcohol

Abstract

High purity isopropyl alcohol cannot be obtained from an aqueous solution by conventional distillation because isopropyl alcohol in solution will reach an azeotropic point around 68 mole % (88 wt.%). However, high purity isopropyl alcohol can be obtained by using ethylene glycol or dimethyl sulfoxide as a solvent in the extractive distillation process, which yields highly purified isopropyl alcohol in the upper part of the distillation column. Herein, the solvent ability of ethylene glycol and dimethyl sulfoxide in the extractive distillation process is compared. In addition, the two-column configuration of the extractive distillation column and solvent recovery column, concentrator, evaporation equipment and the three-column configuration of the extractive distillation column and solvent recovery column are also compared. Computer simulations were conducted for each of the aforementioned processes. Process optimization was also performed for the reduction of utilities cost. The study confirmed that the use of dimethyl sulfoxide as a solvent with application of the three-column distillation configuration was effective for minimizing the consumption of steam.