Abstract
This paper envelops the steady-state simulation of the complete process of extractive distillation for the production of anhydrous ethanol and pure water from the azeotropic mixture of ethanol-water. A system of two connected distillation columns was modelled and simulated with the first column used for the extractive distillation of ethanol and the second column for the recovery of the solvent that made the extractive distillation possible, which is then recycled back to the first column. Anhydrous ethanol as the distillate product leaving the first column and very pure water and ethylene glycol leaving the second column as the distillate and bottoms products, respectively, were the aim of the simulations. These simulations were carried out by a custom equilibrium-stage distillation model programmed and running on EMSO (Environment for Modelling, Simulation, and Optimisation). Their results were compared with those obtained from equivalent simulations performed in Aspen Plus as a way to evaluate the reliability and viability of the custom model, since Aspen Plus has proven its utility and reliability through its usage in industry and research. Results from the EMSO equilibrium-stage model simulations were compared with those from equilibrium-stage Aspen Plus distillation simulations, but in order to compare EMSO results with non-equilibrium stage Aspen Plus distillation results, Barros & Wolf correlations were programmed into the EMSO equilibrium-stage model and used to calculate stage-by-stage efficiencies that were then used by the EMSO model with the aim of approximating the Aspen Plus non-equilibrium stage model results. The comparison of results produced by both EMSO and Aspen Plus simulating equivalent processes showed that, for equilibrium-stage distillation, both simulators were able to produce anhydrous ethanol in the first column and very pure water and ethylene glycol in the second column, with very similar results for both simulators across the entire system. Results for EMSO simulations using Barros & Wolf efficiency correlations and Aspen Plus non-equilibrium stage simulations also showed great similarity between them across the columns.
