Experimental and Regression Vapor–liquid Equilibrium Data for Ethanol + Dipropylene Glycol Binary System

Ethanol is one of the most utilized additives in gasoline, and its obtaining and separation from regenerable resources is of great interest. Despite the enormous energy consumption, extractive and azeotropic distillation is still preferred for ethanol anhydrization. This work studies the utilization of dipropylene glycol (DPG) as an extractive agent. The vapor–liquid equilibrium (VLE) data for the ethanol + DPG binary system was experimentally determined and the VLE data obtained were regressed using Non-Random Two Liquid (NRTL) and Universal Quasi Chemical (UNIQUAC) thermodynamic models in PRO/II 2020 simulation software. The binary interaction parameters obtained from regression were used to simulate the water + ethanol separation by extractive distillation with DPG. There were realized a series of several simulations, using different solvent/feed ratios in the extractive distillation column, starting from two basic variants: variant A, where no heat recovery is considered, and variant B, where the heat of the hot streams in the process flow diagram (PFD) is recovered in three heat exchangers. The specific energy consumption (SEC) expressed as MJ/kg of anhydrous ethanol were calculated for each variant. It was found that the most economical is variant B which for the SEC is 7.53 MJ/kg of anhydrous ethanol. The SEC calculated for the best variant in this study is lower than the SEC calculated by other researchers for similar processes.