Sensitivity analysis and operative conditions of a supercritical fluid extractor

In this paper, a typical analysis of the effect of model uncertainties on predictions is extended to a supercritical extraction process for an extractor feed by vegetable seeds and utilizing supercritical CO2 as solvent. The sensitivity analysis reveals that two parameters are particularly important for the extraction process modeling: the particle diameter and the internal mass transfer coefficient. Therefore, a deeper analysis of the sensitivity of these two parameters has been performed: the sensitivity depends on the length of the process. In the supercritical extraction process, two successive phases can be considered: the former is controlled by the solubility of the oil in the supercritical solvent, and it is therefore almost completely insensitive; the second phase, on the contrary, is mainly controlled by internal transport phenomena and it is very sensitive to the above mentioned parameters. The effect of changing some operative conditions is also investigated, underlining how the solvent flow rate and the seed milling affect the extraction process. From these results, an extraction procedure is proposed that would reduce the solvent consumption without resorting to the connection in series of several extractors.