Development and optimization of a novel process of double‐effect distillation with vapor recompression for bioethanol recovery and vapor permeation for bioethanol dehydration

Abstract

BACKGROUND Bioethanol, an important biofuel, obtained from biomass fermentation is dilute and unsuitable for direct use as fuel for transportation. Its recovery and dehydration to ∼99.5 wt% ethanol is energy‐intensive because of dilute feed (∼10 wt% ethanol) and occurrence of ethanol–water azeotrope. From an energy efficiency perspective, hybrid separation processes consisting of a membrane‐based module coupled with distillation are a promising alternative to conventional separation by distillation alone. RESULTS The present article proposes the novel process of double‐effect distillation with vapor recompression (DED) for bioethanol recovery followed by vapor permeation (VP) for bioethanol dehydration (to 99.8 wt% ethanol) from a ternary feed of ethanol (10 wt%), water (89.9 wt%) and CO2 (0.1 wt%) and compares it with the process of simple distillation followed by vapor permeation (D‐VP). Multi‐objective optimization is performed for both processes, and the obtained Pareto‐optimal solutions for minimizing fixed capital investment and annual operating cost are presented and discussed. Compared with the optimal D‐VP process, the optimal DED‐VP process is found to be better, with 17 and 11% savings in energy consumption and total annual cost (TAC) respectively. CONCLUSION Specific energy consumption (SEC) of the DED‐VP process is 5% lower than that of the hybrid process of distillation for recovery followed by pressure swing adsorption for dehydration (D‐PSA) used industrially. Continued developments in membranes that can provide high permeance, selectivity and/or operating life can further reduce TAC and SEC of the DED‐VP process. © 2018 Society of Chemical Industry

Combined Vapor Permeation and Continuous Solid-State Distillation for Energy-Efficient Bioethanol Production

“…Therefore, energy-efficient bioethanol production technologies attracted considerable attention [11][12][13]. In the conventional process of bioethanol production, the recovery of Energies 2021, 14, 2266 2 of 15 ethanol from fermentation broth is accomplished by a rectification column which yields an ethanol-water azeotrope of 95.4 wt% ethanol.…”

Economic Assessment of Bioethanol Recovery Using Membrane Distillation for Food Waste Fermentation

“…At least 40% of the total energy consumption in ethanol production is coming from the distillation process [10]. Several methods are recommended to substitute the distillation process, such as reverse osmosis and membrane distillations [11]. The membrane provides an alternative option, either using hydrophobic or hydrophilic membranes to separate ethanol from the fermentation broth.…”

“…Moreover, the membrane performance varies based on membrane selectivity, operational conditions, and types and size of polymers [12]. Therefore, membrane distillation is considered more efficient, easy to operate, and with a low energy requirement [11,[13][14][15][16]. There are several studies that have been done by previous researchers regarding membrane distillation for ethanol production from different feedstock.…”

Control of extractive distillation processes with intermediate impurities removed as a side withdrawal from the extractive distillation column

“…applied heat‐pump to the former novel ED dividing‐wall column to further reduce energy consumption. Singh and Rangaiah incorporated double‐effect distillation, vapor recompression and vapor permeation in ED for ethanol dehydration. Liang et al .…”