Multi-scale experimental study and modeling of the supercritical fractionation process

In this work, the fractionation of water-ethanol mixtures by supercritical carbon dioxide at 333 K and 10.1 MPa was used as a model system to compare experimental extract and raffinate compositions and overhead loadings at laboratory, pilot and industrial scales to contribute toward a sizing methodology for counter-current supercritical fractionation columns. A series of three columns with an internal diameter of 19, 58 and 126 mm and with a height of 2, 4 and 8 m respectively were used for the different scales, meaning scaling factors from 9 to 44 between columns. The massic solvent-to-feed ratio was varied between 5.2 and 78.8. Experimental results at the different scales are analyzed and compared from the thermodynamic, mass transfer and column hydrodynamics points of view; and also using process simulation by equilibrium-stage models. In total, 42 successful experimental runs are taken into account, including 6 at a pilot scale unit and 2 at an industrial scale. (authors)