MASS-TRANSFER IN A SEMIBATCH SUPERCRITICAL FLUID EXTRACTION CONTACTOR FOR LIQUID-MIXTURES

The problem of mass transfer in a semibatch Supercritical Fluid Extraction contactor for liquid mixtures has been considered both theoretically and experimentally. The multicomponent mass transfer model is applied to the case of a gaseous solvent rising through the liquid to be extracted. The results obtained with this model are compared with those calculated by using a liquid—liquid extraction model recently extended to supercritical extraction contactors. A simplified model is developed and all of the models considered are tested on the basis of experimental data points. Experiments are carried out in a semi-batch pilot-size apparatus and results are presented for the systems Ethanol-Water-CO2at 17.0 MPa, 308 K and Isopropanol-Water-CO2at 10.3 MPa, 313 K. Models based on the gas-liquid extraction approach are capable of representing the concentration versus time profiles at the extractor, while the liquid—liquid approach predicts lower extraction effectiveness. © 1990, Taylor & Francis Group, LLC. All rights reserved.