FOULING REDUCTION IN SUPERCRITICAL EXTRACTION UNITS

摘要

A residual petroleum fraction feed is subjected to a deasphalting process by solvent extraction using a light paraffinic solvent with recovery of the solvent under supercritical process conditions. Fouling is reduced by the injection of an aromatic stream into the DAO-solvent stream from the extractor in order to provide a degree of solvency for residual asphaltenes in the DAO-solvent stream which otherwise would tend to precipitate in the heat exchanger used to create the supercritical conditions for the solvent. The aromatic solvent stream which, by its aromatic character, has solvency properties for the asphaltene components remaining in the DAO-solvent stream, is selected to have a boiling point above the boiling point of the solvent so that it does not contaminate the process solvent when the solvent is recovered in the solvent recovery section of the unit.