A Coupling Process of Distillation with Vapor Permeation and Adsorption for Production of Fuel Ethanol: A Comparative Analysis on Energy Consumption

Abstract

To efficiently produce fuel ethanol from fermentation broth, the distillation column was coupled with vapor permeation (VP) of a NaA zeolite membrane instead of using the adsorption technique to remove solvent water. The comparative analysis indicated that the energy efficiency was consistently higher for distillation-VP coupling, using a single-column distillation and threecolumn distillation, respectively. The best performance was obtained for the VP membrane coupling with a three-column distillation technique, where only 2.7 tons of steam per ton of fuel ethanol were consumed to produce fuel ethanol using a 3.0 wt % ethanol broth. This saved 0.25 tons of steam per ton of fuel ethanol in comparison with the results for the coupling with adsorption technique. The effect of ethanol content in broth on the energy efficiency was also investigated, which indicated that the ethanol content was a decisive factor to determine the energy consumption in the coupling techniques. The operation pressures were crucial to balance the energy consumption between columns coupled with the VP membrane. It was found that the operation pressure of the low-pressure column was the decisive factor to the whole energy efficiency, while the pressure of the high-pressure column was preferably adjusted according to practical production due to fewer disturbances in the system. This work benefits the process design for production of fuel ethanol from fermentation broth.

A Novel Internal Coupling Process of a T-type Zeolite Membrane in a Distillation Column to Separate the PM/H2O Mixture

“…In the ACM, a plug flow was used to construct the VP model and an Arrhenius-type semiempirical equation was used to describe the penetration behavior of each component across the membrane, ,− defined by J i = k i nobreak0em0.1em⁡ exp ( − E i R normalg T ) ( x i P normalF − y i P normalP ) where the two parameters E i and k i represent the apparent activation energy (kJ·mol –1 ) and permeability coefficient (kg·m –2 ·h –1 ) for a given component, respectively, determined by fitting the experimental data. P F and P P correspond to the total pressures in the feed and permeate (kPa), respectively, which varied along the membrane module.…”

Process intensification by integration of distillation and vapor permeation or pervaporation - An academic and industrial perspective

“…Obtaining the azeotropic composition in the distillate stream, VP or PV allows for a final purification, especially if the azeotropic point occurs at high concentrations of the low boiler. The most prominent example among others is the dehydration of ethanol, which was subject to several studies [31,[34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. Some of these are summarized in the following.…”

Enhanced n‐butanol permselective vapor permeation by incorporating ZIF‐8 into a polydimethylsiloxane composite membrane: Effect of filler loading contents

“…Biobutanol is considered a superior fuel to bioethanol because of its lower volatility, higher energy density, and better blending with gasoline with petroleum, [1] and thus received enthusiastic attention in recent years. Vapor permeation (VP) is a promising membrane based separation technique that offers several attractive features including energy‐saving, being completely harmless to microorganisms, and little membrane deterioration, [4,5] and thus is considered as a promising technique to realize efficient recovery of biobutanol from biomass fermentation broth [2,3] . According to the well‐known “solution‐diffusion” mechanism, [6,7] mass transport in the VP process include three major steps: (i) permeate molecules’ adsorption on the membrane surface, (ii) inner membrane diffusion, and (iii) downstream evaporation.…”

“…Vapor permeation (VP) is a promising membrane based separation technique that offers several attractive features including energy-saving, being completely harmless to microorganisms, and little membrane deterioration, [4,5] and thus is considered as a promising technique to realize efficient recovery of biobutanol from biomass fermentation broth. [2,3] According to the well-known "solution-diffusion" mechanism, [6,7] mass transport in the VP process include three major steps: (i) permeate molecules' adsorption on the membrane surface, (ii) inner membrane diffusion, and (iii) downstream evaporation. Since steps (i) and (ii) are usually rate-limiting, the performance of the VP membrane plays a significant role in this process.…”