Modeling and simulation of the supercritical CO2 extraction of vegetable oils

The model of broken and intact cells has been applied to the experimental r esults on oil sled supercritical extraction obtained by various authors and on several species of seeds. The results analyzed are related to various e xtraction apparatus ranging from very low laboratory scale to pilot plants. Moreover, a wide range of operating conditions has been covered, CO2 flow rates ranging between 1.5 and 750 g/min. extraction pressures from 240 to 5 50 bar. temperatures between 25 and 50 degreesC and particle diameters from 0.25 to 4 mm have been considered. Besides, the experimental results exist ing in the literature, systematic scanning electron microscope (SEM) analys is have been performed on seed particles belonging re, the different seed s pecies studied, thus obtaining data about the microscopic cells that bear t he oil that are characteristic of the different seed structures. operating in this manner the differential mass balances that characterize this kind o f models have been supported by microscopic information on seed structure a nd the number of adjustable parameters in the model has been reduced to onl y one. the internal mass transfer coefficient (k(i)). A fair good fitting o f all the available experimental results has been obtained using best fit k (i) values ranging between 2.4 x 10(-7) and 9.2 x 10(-8) m/s and producing a coherent description of the extraction process. Some simulation tests hav e also been performed that evidenced the role of particle size and of inter nal mass transfer and of their interaction on the overall performance of th e extraction process. (C) 2001 Elsevier Science B.V. All rights reserved.