Phase Behavior of CO_2/Crude Oil Mixtures in Supercritical Fluid Extraction System: Experimental Data and Modeling

摘要

Continuous multiple-contact extractions of a crude oil were carried out with supercritical CO_2 in order to assess the effect of the density and critical point of a solvent on the extraction performance as a function of process variables. Most of the extraction performance was solvent density dependent. In the vicinity of the critical point of CO_2, however, the solvent density was not the only parameter that governed extraction yields. The results of simulated distillation and gas chromatography—mass spectrometry analyses of extracts represented that the earlier extracts contained lighter compounds and the latter extracts contained progressively heavier compounds. As the extraction proceeded, relatively greater amounts of paraffinic compounds and lesser amounts of naphthenic and aromatic compounds were extracted. This compositional change occurring during a dynamic extraction was also ascertained by phase equilibrium calculations using the Soave-Redlich-Kwong equation of state and a component-lumping procedure.