Solvent extraction process for treatment of highly aromatic feed stocks

Claim 1

A PROCESS FOR RECOVERING AN AROMATIC HYDROCARBON FROM A HYDROCARBON MIXTURE CONTAINING AROMATIC AND NON-AROMATIC HYDROCARBONS OF WHICH THE AROMATIC CONTENT IS AT LEAST 75% BY WEIGHT OF SAID MIXTURE, WHICH COMPRISES INTRODUCING SAID MIXTURE AND A SOLVENT COMPOSITION, FORMED AS HEREINAFTER SET FORTH, TO THE UPPER PORTION OF A STRIPPING COLUMN AND THEREIN SUBJECTING THE MIXTURE TO EXTRACTIVE DISTILLATION WHILE MAINTAINING THE SOLVENT COMPOSITION AT A TEMPERATURE ABOVE THE BOILING POINT OF SAID MIXTURE AND BELOW THE BOILING POINT OF THE SOLVENT, FORMING THEREBY A RICH SOLVENT PHASE CONTAINING A SUBSTANTIAL PROPORTION OF THE AROMATIC COMPONENTS OF SAID MIXTURE, REMOVING A VAPOR OVERHEAD COMPRISING THE NON-AROMATIC HYDROCARBONS PRESENT IN SAID MIXTURE FROM THE UPPER PORTION OF THE DISTILLATION COLUMN, VAPORIZING AN AROMATIC FRACTION AND FROM SAID RICH SOLVENT PHASE IN AND REMOVING THE SAME FROM AN INTERMEDIATE PORTION OF THE COLUMN, REMOVING A LEAN SOLVENT RESIDUE FROM THE LOWER PORTION OF THE COLUMN, CONDENSING SAID VAPOR OVERHEAD AND SUBJECTING THE RESULTANT CONDENSATE TO LIQUID PHASE SOLVENT EXTRACTION BY COUNTERCURRENT CONTACT WITH SAID LEAN SOLVENT RESIDUE IN AN INDEPENDENT EXTRACTION ZONE, AND INTRODUCING THE RESULTANT ENRICHED SOLVENT FROM SAID INDEPENDENT ZONE TO THE UPPER PORTION OF THE DISTILLATION COLUMN AS SAID SOLVENT COMPOSITION.