Segregation and recovery of naphthenic hydrocarbon concentrates

Claim 1

IN A PROCESS FOR SEPARATING IN A COUNTER-CURRENT PRIMARY SOLVENT EXTRACTION ZONE A MIXTURE OF HYDROCARBONS COMPRISING PARAFFINIC, NAPHTHENIC AND AROMATIC MIXPONENTS, EMPLOYING A SOLVENT MORE DENSE THAN SAID MIX TURE AND IN WHICH THE NAPHTHENIC AND AROMATIC COMPONENTS ARE AT LEAST PARTIALLY SOLUBLE, REMOVING FROM THE LOWER PORTION OF SAID ZONE A PRIMARY FAT SOLVENT STREAM, AND REMOVING FROM THE UPPER PORTION OF SAID ZONE A RAFFINATE COMPRISING THE PARAFFINIC COMPONENTS OF SAID MIXTURE, THE METHOD WHICH COMPRISES INTRODUCING SAID MIXTURE INTO SAID ZONE AT A POINT BETWEEN THE RAFFINATE AND FAT SOLVENT OUTLETS OF SAID ZONE, VAPORIZING FROM SAID PRIMARY FAT SOLVENT A LIGHT OVERHEAD COMPRISING AROMATIC AND NAPHTHENIC HYDROCARBON COMPONENTS OF SAID MIXTURE, SUBJECTING AT LEAST A PORTION OF SAID OVERHEAD TO SOLVENT EXTRACTION IN A SECONDARY EXTRACTION ZONE AND THEREIN SEPARATING NAPHTHENIC FROM AROMATIC COMPONENTS, RECOVERING A SECONDARY RAFFINATE FROM SAID SECONDARY ZONE COMPRISING THE RELATIVELY LOW MOLECULAR WEIGHT NAPHTHENIC COMPONENTS OF SAID MIXTURE, AND RECYCLING A REFLUX STREAM SELECT ED FROM THE GROUP CONSISTING OF (1) A PORTION OF SAID SECONDARY RAFFINATE AND (2) A PORTION OF SAID LIGHT OVERHEAD TO SAID PRIMARY EXTRACTION ZONE, AND INTRODUCING SAID REFLUX INTO SAID PRIMARY EXTRACTION ZONE BELOW THE INLET OF SAID MIXTURE THEREIN.