RATE OF THE VEGETABLE OIL EXTRACTION WITH SUPERCRITICAL CO2 .2. EXTRACTION OF GRAPE OIL

Grape oil was extracted with carbon dioxide at 280 bar and 40 degrees C. Effect of milling of grape seeds, solvent flow rate and flow direction on the course of extraction was investigated. Mass transfer coefficients in the supercritical and solid phases were evaluated from extraction curves using a plug-flow model. While the assumption of plug flow was confirmed in the experiments with downflow of CO2 through the bed of milled material, the extraction with upflow of CO2 retarded due to the natural convection. The smaller was the amount of milled seeds in the extractor and the slower was the upward flow, the more pronounced was this effect. A model with parallel plug flows was able to give good representation of the extraction curves measured with upflow.