Exergy Analysis of an Extractive Distillation Column for Reducing Energy Consumption in a Bioethanol Production Process

This work focuses on the exergy analysis of an extractive distillation column in the second-generation bioethanol production process. The study of the exergy performance of the separation and purification section is relevant from a thermodynamic point view due to the large amount of the energy consumed by their unit operations. A sensitivity analyses of the separation section, the location of the feeding stages for the solvent and the ethanol-water azeotropic mixture, the reflux ratio and solvent/feed ratio were performed for obtaining the minimum energy consumption in the column reboiler. Finally, the profiles of exergy components, irreversibilities and the exergy efficiency for the base case and enhanced case were compared. The results show a 29.21 % decrease on the irreversibilities and a corresponding increase of 22.82 % in the exergy efficiency for the separation section. The simulation as well as the sensitivity analyses were done using a connection between the process simulator Aspen Plus v 8.8 and Excel.