Process intensification by the use of micro devices for liquid fractionation with supercritical carbon dioxide

Abstract

The present study is focused on the process intensification of extraction with supercritical fluids by using micro-devices. The main purpose is to investigate the efficiency and applicability of micro-mixers in supercritical fluid extraction processes. Two micro-devices with different mixing principles, multilamination and T-type lamination, were used and results were compared. The extraction experiments were carried out in a micro-device apparatus designed for high-pressure processes, in which the micro-device is the unit where the solvent and the liquid feed come into contact. Experiments on the continuous extraction of ethanol from aqueous solutions using supercritical CO2 as solvent were performed to study the feasibility of the extraction process in a micro-device apparatus. The separation of both liquid and vapour phases was achieved by changes of temperature and pressure. The experiments were carried out at 101bar and 60°C. Different ethanol concentrations in the feed and solvent-to-feed ratio values were considered. Results obtained with the two different micro-devices were compared. A phase equilibrium model using Peng Robinson equation of state was developed in ASPEN-Plus® and calculations were performed to confirm that equilibrium was achieved through the extraction process and that one theoretical stage can be reached in a micro-device stage.