Solvent extraction process

Claim 1

A COMBINATION SOLVENT EXTRACTION-RICH SOLVENT STRIPPING PROCESS FOR SEPARATING ISOPRENE FROM A STREAM CONTAINING THE SAME AND ISOPENTANE COMPRISING CONTACTING SAID STREAM WITH A SOLVENT MIXTURE COMPRISING WATER AND THE MONOMETHYL ETHER OF DIETHYLENE GLYCOL IN AN EXTRACTION ZONE FORMING THEREBY A RAFFINATE COMPRISING ISOPENTANE AND AN EXTRACT COMPRISING SAID SOLVENT MIXTURE AND ISOPRENE INTRODUCING SAID EXTRACT INTO A STRIPPING ZONE WHEREBY THERE IS PRODUCED AN OVERHEAD STREAM COMPRISING ISOPRENE AND A PORTION OF THE WATER AND A BOTTOM STREAM COMPRISING THE MONOMETHYL ETHER OF DIETHYLENE GLYCOL AND THE REMAINDER OF THE WATER, COOLING SAID OVERHEAD IN A FIRST CONDENSATION ZONE TO CONDENSE A PORTION OF THE WATER THEREIN BUT NOT SAID ISOPRENE, RETURNING SAID CONDENSED WATER TO SAID STRIPPING ZONE AS REFLUX, COOLING THE REMAINDER OF SAID OVERHEAD STREAM IN A SECOND CONDENSATION ZONE TO CONDENSE SAID ISOPRENE AND THE REMAINDER OF THE WATER THEREIN, SEPARATING SAID CONDENSED IOSPRENE FROM SAID WATER AND RECOVERING SAID CONDENSED ISOPRENE AS A PRODUCT OF THE PROCESS RETURNING WATER SEPARATED FROM SAID ISOPRENE TO SAID EXTRACTION ZONE, AND CONDENSING IN SAID FIRST CONDENSATION ZONE ALL BUT THE AMOUNT OF WATER RETURNED TO SAID EXTRACTION ZONE BY VARYING THE AMOUNT OF COOLING IN SAID FIRST CONDENSATION ZONE RESPONSIVE TO THE CHANGES IN DEMAND FOR WATER BY SAID EXTRACTION ZONE.