DYNAMIC BEHAVIOR OF SUPERCRITICAL-FLUID EXTRACTIONS OF A CRUDE-OIL AND ITS VACUUM RESIDUE

Dynamic extraction of a crude oil and its vacuum residue was carried o ut with supercritical carbon dioxide and propane to understand the nat ure of the extraction and partitioning processes as a function of pres sure and temperature. The overall extraction performance of a solvent was governed by a complex interplay between extraction efficiency and feedstock volatility (heaviness). The extraction efficiency and extrac tive power of the solvent were linked to the solvent density, which in creases with pressure. Enhanced solvating power of the solvent near th e critical temperature of the pure solvent was evident when the extrac tion yields with respect to temperature were evaluated. Composition va riations during an extraction sequence were determined by simulated di stillation analysis of extracted samples. The results showed that the earlier extracts contained lighter compounds and the later extracts pr ogressively heavier compounds. Differences in composition between extr acted samples assessed by g.c.-m.s. provided evidence of composition v ariations. Copyright (C) 1996 Elsevier Science Ltd.