Obtenção de etanol anidro via destilação extrativa: simulação e otimização.

Abstract

This work has as main objective to carry out a study with the focus on the simulation and optimization of the process of acquisition of alcohol anhydrous through extractive distillation. The study system for this work will be composed by ethanol(1)/water(2), which forms a homogeneous azeotropic, with the amount of etanol equal to 89.0% molar, corresponding to 95.6% mass, in 78.15°C. Ethylene glycol was chosen as solvent for the system in study because it does not form additional azeotropes in the extractive distillation column. The specific objectives of this work are the simulation in the stationary stage using the commercial Aspen Plus™ simulator (version 20.0) as tool; analysis of sensitivity of project variables and operation of the extractive distillation and optimization of the process. The simulated extractive distillation process is similar to the ones verified in some industries that produce anhydride ethanol, which use this exactly same separation process. The purpose of the extractive distillation column is to produce anhydride ethanol as top product in a molar composition of 99.5%, due to the original azeotropic mixture ethanol (1)/water (2) which presents molar composition of 85% of hydrated ethanol. In the recovery column, the separation between the water and the solvent is obtained, where the base product is cooled and recycled to the extractive column. The studied variables in the sensitivity analysis were: reflux ratio of the extractive column; separation agent feeding stage; azeotropic mixture feeding stage; molar outflow of solvent feeding; distilled molar outflow; feeding solvent temperature; azeotropic feeding mixture temperature. After that, a non sequential optimization was carried out in each column, evaluating all the decision variables, looking for the ideal point. Finally, a sequential simulation of the conventional configuration was made. Although the number of studies involving optimization of columns of extractive distillation is high, no publications were found using this type of optimization procedure during this bibliographical research. The studies are being made correlating in a maximum of 2 decision variables. There was reduction of 9.00% in the thermal load of the extractive column reboiler, whereas in the recovery column it was verified a 22.20% reduction.