SUPERCRITICAL-FLUID EXTRACTION OF FUNGAL LIPIDS - EFFECT OF COSOLVENTON MASS-TRANSFER RATES AND PROCESS DESIGN AND ECONOMICS

The extraction of fungal lipids by supercritical CO2 and CO2 with 10 w t % ethanol was studied. The lipid solubility was measured from 40-60 degrees C and 200-700 bar, and was found to increase with increasing s olvent pressure and temperature, although the crossover effect was obs erved. Mass transfer coefficients were fitted to experimental data and were found to increase with increasing solvent Reynolds number. No di fference in mass-transfer coefficients was observed with the addition of the cosolvent, Using the experimental data, a mathematical model fo r a commercial extraction process was developed, and optimal values of the extractor pressure, solvent flow rate, and extraction time were c omputed. Since the lipid is more soluble in the CO2 mixture, the optim al extractor pressure and extraction time were lower than those comput ed for a process with a pure CO2 solvent. Capital and operating costs for the process were estimated and the addition of the cosolvent was f ound to lower the costs by over 40%. A comparison of the costs for the SFE process and the costs for a liquid-extraction process show that t he SFE process is not competitive for this application, although the e conomics would be improved if wet. fungal mycelia were contacted conti nuously with the supercritical solvent.