Solvent extraction and recovery of solvent

Claim 1

IN A PROCESS FOR RECOVERING A SOLVENT FROM A LIQUID EXTRACT SOLUTION CONTAINING THE SOLVENT SUBSTANTIALLY SATURATED WITH A HYDROCARBON OIL HAVING AN ATMOSPHERIC BOILING POINT BETWEEN ABOUT 175 AND 1000*F., SAID SOLVENT BEING CAPABLE OF BEING COMPRESSED ADIABATICALLY FROM A SATURATED VAPOR TO A SUPERHEATED VAPOR, THE IMPROVEMENT WHICH COMPRISES PASSING THE SUBSTANTIALLY SATURATED EXTRACT SOLUTION FROM AN EXTRACTION ZONE SUBSTANTIALLY AT EXTRACTION TEMPERATURE AND PRESSURE TO A DISTILLATION ZONE, EVAPORATING SOLVENT FROM SAID SATURATED SOLUTION IN THE DISTILLATION ZONE SUBSTANTIALLY AT SAID EXTRACTION TEMPERATURE AND PRESSURE SO THAT THE RESULTING RESIDUAL LIQUID BECOMES A TWO-PHASE SYSTEM CONTAINING A SOLVENT-RICH PHASE AND AN OIL-RICH EXTRACT PHASE, WITHDRAWING THE RESULTING SOLVENT VAPOR OVERHEAD FROM THE DISTILLATION ZONE, COMPRESSING SUBSTANTIALLY ALL OF THE WITHDRAWN SOLVENT VAPOR SUFFICIENTLY TO HEAT IT AT LEAST 20* F. F. ABOVE THE TEMPERATURE OF SAID RESIDUAL LIQUID PRESENT IN THE DISTILLATION ZONE, PASSING THE COMPRESSED HOT SOLVENT VAPOR IN INDIRECT HEAT EXCHANGE WITH THE LIQUID PRESENT IN THE DISTILLATION ZONE, WHEREBY THE COMPRESSED SOLVENT VAPOR IS CONDENSED AND ADDITIONAL SOLVENT IS EVAPORATED FROM THE EXTRACT SOLUTION, RECOVERING THE CONDENSED SOLVENT, WITHDRAWING SAID RESIDUAL TWO-PHASE LIQUID FROM THE DISTILLATION ZONE, AND MECHANICALLY SEPARATING SAID RESIDUAL LIQUID INTO A SOLVENT-RICH PHASE AND AN OIL-RICH EXTRACT PHASE.