Process for separating aromatic hydrocarbons

Claim 1

A PROCESS FOR THE EXTRACTION AND RECOVERY OF AROMATIC HYDROCARBONS FROM A LIQUID HYDROCARBON MIXTURE CONTAINING AROMATIC AND NON-AROMATIC HYDROCARBONS COMPRISING (1) INTRODUCING THE MIXTURE INTO A COUNTER-FLOW MULTI-STAGE EXTRACTION SYSTEM WHEREIN THE TEMPERATURE IS MAINTAINED BETWEEN 140 AND 170*C.; (2) INTRODUCING, AT ONE END OF THE EXTRACTION SYSTEM, A HIGH BOILING, AROMATIC SELECTIVE SOLVENT HAVING A NORMAL BOILING TEMPERATURE WITHIN THE RANGE OF 225*C. TO 295*C. AND WHICH SOLVENT CONTAINS DISSOLVED WATER IN THE PROPORTION OF NOT MORE THAN 2% BY WEIGHT; (3) PASSING THE SOLVENT IN COUNTERCURRENT FLOW TO THE HYDROCARBON MIXTURE TO OBTAINED A SOLVENT EXTRACTED PHASE ENRICHED IN AROMATICS; (4) COOLING THE AROMATIC-RICH EXTRACTED PHASE WITHDRAWN FROM THE OTHER END OF THE EXTRACTION SYSTEM BY AT LEAST 15*C. TO A TEMPERATURE BETWEEN 115*C AND 150*C., (5) INTRODUCING THE THUS COOLED EXTRACTED PHASE WITHOUT APPRECIABLE FLASH VAPORIZATION INTO A STRIPPING ZONE, WHICH IS OPERATED AT A PRESSURE OF AT LEAST 1.5 ATMOSPHERES ABSOLUTE, AT A TOP TEMPERATURE BETWEEN 115*C. AND 150*C. AND AT A BOTTOM TEMPERATURE OF AT LEAST 165*C. TO SEPERATE OVERHEAD A VAPOR PHASE ENRICHED IN NON-AROMATIC HYDROCARBONS; (6)CONDENSING THE VAPOR FROM SAID ZONE AND RECYCLING THEM TO THE EXTRACTION SYSTEM AFTER REMOVING SUBSTANTIALLY ALL WATER PRESENT AS A SECOND LIQUID PHASE, WITH THE CONDENSES VAPORS BEING INTRODUCED INTO THE EXTRACTION SYSTEM BETWEEN THE INTERMEDIATE POINT OF THE SYSTEM AND THE END AT WHICH THE EXTRACTED PHASE IS WITHDRAWN; (7) WITHDRAWING THE LIQUID REMAINDER OF THE EXTRACTED PHASE FROM THE STRIPPING ZONE AND SEPERATING THE SOLVENT FROM THE HYDROCARBONS THEREOF IN A DISTILLING ZONE AT A PRESSURE OF LESS THAN 0.5 ATMOSPHERE ABSOLUTE, SAID ZONE HAVING A BOTTOM TEMPERATURE OF AT LEAST 145*C., WHICH IS AT LEAST 10*C. LOWER THAN THE BOTTOM TEMPERATURE IN THE STRIPPING ZONE.