Supercritical-Fluid Extraction Calculations for High-Boiling Petroleum Fractions Using Propane. Application of Continuous Thermodynamics

摘要

Supercritical-fluid extraction is a useful process for upgrading heavy multicomponent mixtures such as high-boiling petroleum fractions. Design-oriented calculations are reported for an extraction process using propane to extract intermediate components from a petroleum fraction with molecular weights in the range 150 to 500. The composition of the heavy-hydrocarbon mixture is described by two continuous distribution functions of molecular weight, one for paraffinic and one for aromatic components. Process calculations are based on a recently developed thermodynamic framework for mixtures with very many components, coupled with an equation of state of the van der Waals form. Particular attention is given to multicomponent phase equilibria in the retrograde region where solvent recovery is favorable. Quantitative results are given for solvent capacity and selectivity as a function of operating conditions. (ERA citation 09:030234)