Advanced Exergy Analysis-Based Reactive-Extractive Distillation Process Design and Heat Integration for the Recovery of Tert-Butanol and Ethanol from Wastewater

Abstract

In producing ethyl tert-butyl ether (ETBE) using aqueous bioethanol and isobutylene, substantial amounts of industrial wastewater containing ethanol (EtOH) and tert-butyl alcohol (TBA) are made. Reactive-extractive distillation (RED), which integrates reactive distillation (RD) and extractive distillation (ED) in a single column, was proposed for the recovery of TBA and EtOH from wastewater. Exergy analysis pinpoints energy waste and reveals opportunities for efficiency gains. Specifically, the feasibility of the RED was investigated using thermodynamic analysis and residue curve maps. Intensified double-column extractive distillation (DCRED), compared to triple-column extractive distillation (TCED), is proposed based on a literature-reported reaction kinetic model and experimental data-verified UNIQUAC model. Two heat-integrated configurations of DCREDHI1 and DCREDHI2 were designed based on advanced exergy analysis of the component with avoidable exergy destruction. A genetic algorithm was utilized to optimize the operational parameters targeting the minimization of TAC, and evaluation was conducted focusing on economic viability, environmental sustainability, and exergetic performance. Results demonstrated that the DCREDHI2 significantly outperforms TCED, achieving reductions of 76.74% in TAC, 72.43% in CO2 emissions, and 29.23% in exergy destruction. This work contributes to advancing sustainable industrial practices by providing effective strategies for process intensification and energy optimization.

Keywords: Reactive-extractive distillation, advanced exergy analysis, genetic algorithm optimization, tert-butanol/ethanol/water