MATHEMATICAL-MODELING OF SUNFLOWER SEED EXTRACTION BY SUPERCRITICAL CO2

Extraction of oil from crushed sunflower seeds with supercritical CO2 was performed at 280 bar and 40 degrees C on a laboratory apparatus of 0.15 x 10(-3) m(3) volume and on a pilot plant of 1.5 x 10(-3) m(3) v olume. CO2 now rate ranged between 5 and 45 kg h(-1). To study the inf luence of the vegetable matrix on the extraction rate, a re-extraction experiment on the extraction product was also performed on the pilot scale apparatus. A mathematical model of the supercritical extraction process was developed on the basis of the experimental evidence. The e quilibrium between the solids and the fluid phase appeared to be the c ontrolling step during the extraction process. A simplified form of a sigmoidal-shaped equilibrium curve was adopted to fit the experimental data in the whole range of CO2 flow rates explored. The meaning of th is nonlinear equilibrium relationship was also discussed.