Equilibrium Theory Analysis of Vacuum Swing Adsorption for Separation of Ethanol from CO₂ in a Beverage Dealcoholization Process

Abstract

In this study, a Vacuum Swing Adsorption (VSA) process was designed to recover ethanol from a binary gas mixture of ethanol and CO2. The VSA feed gas originates in the process of alcoholic beverage dealcoholisation where ethanol is stripped off the standard beer by CO2 flowing upward in the exchange column. The CO2 recovery of the ethanol removal VSA has to be maintained as high as possible in order to improve the ethanol removal efficiency and reduce the energy consumption for both vacuum pump and ethanol trap. To this end, an ethanol recovery four-step VSA unit using MFI zeolites was analysed by Equilibrium Theory in which both non-linearity of ethanol isotherm and incomplete purge were taken into account. The theoretical study revealed that the extent of purge had to be slightly greater than its minimum usage to achieve the maximum CO2 recovery. In addition, the power consumption for evacuation and the process productivity per cycle were estimated. It turned out that, to minimise the specific power consumption, high desorption pressure and low extent of purge would be favoured. With a view to maximising the process productivity per cycle, the extent of purge has to be large. At the high extent of purge, the specific energy consumption can be saved by having the VSA run at low desorption pressure.

Optimization Strategy for Enhancing the Product Recovery of a Pressure Swing Adsorption through Pressure Equalization or Co-current Depressurization: A Case Study of Recovering Hydrogen from Methane

“…In this work, the governing equations are expressed in reference to the past works. − The feed is a binary gas mixture of strongly adsorbing component A and weakly adsorbing component B. The gas is assumed to be an ideal gas.…”