Energy-efficient and ecologically friendly hybrid extractive distillation using a pervaporation system for azeotropic feed compositions in alcohol dehydration process

A hybrid extractive distillation column (EDC) with high selectivity pervaporation (PV) is implemented in three alcohol dehydration processes. For these dehydration processes, glycerol is chosen as an entrainer. Initially, a conventional configuration using two columns in sequence, one of which is an EDC and the other is a recovery column (RC) for separating the glycerol/water mixture, is introduced. However, such a conventional configuration is expensive and requires high energy owing to the low operating pressure conditions in the RC to avoid glycerol degradation. To overcome these limitations, a high selectivity PV from a cellophane membrane is proposed to replace the RC used in the conventional configuration for separating the glycerol/water mixture. In the hybrid configuration, the membrane cost increases owing to the presence of some glycerol at the bottom of the EDC. However, the operating cost reduces due to less energy requirement. Consequently, the simulation results show that the hybrid configuration can save up to 25% and 41% of the total annual cost and energy, respectively, compared to those of the conventional configuration. The proposed hybrid configuration for the alcohol dehydration process using glycerol as an entrainer is a promising technology for real-life industrial applications owing to the availability of a commercial cellophane membrane. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.