Solvent extraction

Claim 1

A SOLVENT EXTRACTION PROCESS FOR THE SEPARATION OF AROMATIC HYDROCARBON FROM A MIXTURE THEREOF WITH NONAROMATIC HYDROCARBONS WHEREIN SAID MIXTURE IS CONTACTED WITH A SELECTIVE SOLVENT IN AN EXTRACTION ZONE TO FORM A RAFFINATE AND A RICH SOLVENT STREAM, SAID SOLVENT CONTAINING A PRIMARY SOLVENT LESS VOLATILE THAN SAID AROMATIC HYDROCARBONS, AND A WATER CONTENT OF FROM 4 TO 20 WEIGHT PERCENT, VAPORIZING FROM THE RICH SOLVENT STREAM DISSOLVED HYDROCARBONS, PART OF THE WATER AND SOME PRIMARY SOLVENT IN A REBOILED SOLVENT STRIPPING ZONE THEREBY FORMING A LEAN SOLVENT SEPARATELY COOLING OVERHEAD AND SIDESTREAM ELFFLUENT FROM THE STRIPPING ZONE, RECOVERING SOLVENT-CONTAINING WATER STREAMS FROM THE RESULTING STRIPPER VAPORS TO PRODUCE AN OVERHEAD RECYCLE FRACTION RICH IN NON-AROMATIC AND A SUBSTANTIALLY PURE AROMATIC PRODUCT AS A SIDESTREAM, SAID AROMATIC PRODUCT STREAM AND SAID RAFFINATE STREAM FROM THE EXTRACTOR BEING WATER WASHED TO RECOVER TRACES OF PRIMARY SOLVENT AND TO PRODUCE EFFLUENTS OF SOLVENT-CONTAINING WATER STREAMS, THE IMPROVEMENT IN SAID PROCESS WHICH COMPRISES MAINTAINING THE STRIPPING ZONE AT SUPERATMOSPHEREIC PRESSURE TO OBTAIN A LEAN SOLVENT OF SUBSTANTIALLLY HIGHER TEMPERATURE THAN THE TEMPERATURE IN THE EXTRACTION ZONE, PASSING ALL SAID SOLVENT-CONTAINING WATER STREAMS TO A FRACTIONATING ZONE, REBOILING SAID FRACTIONATING ZONE BY INTRODUCING A SUBSTANTIAL PART OF SAID LEAN SOLVENT FROM THE STRIPPING ZONE IN FLASHING RELATION TO THE BOTTOM OF SAID FRACTIONATING ZONE, THEREBY OBTAINING SUBSTANTIALLY PURE WATER OVERHEAD, AND A LEAN SOLVENT BOTTOMS OF LOWER HEAT CONTENT AND DESIRED CONTENT OF WATER FOR REUSE IN THE EXTRACTION SECTION.