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.