Process for the extraction and recovery of aromatic hydrocarbons from hydrocarbon mixtures

Claim 1

A PROCESS FOR THE SEPARATION OF A PLURALITY OF AROMATIC HYDROCARBONS OF THE BENZENE SERIES FROM A MIXTURE THEREOF WITH NON-AROMATIC HYDROCARBONS WHICH COMPRISES INTRODUCING THE MIXTURE INTO A COUNTERFLOW MULTISTAGE EXTRACTION SYSTEM NEAR THE MIDDLE; INTRODUCING A GLYCOLIC SELECTIVE SOLVENT, WHICH IS SUBSTANTIALLY IMMISCIBLE WITH NON-AROMATIC HYDROCARBONS, INTO ONE END OF THE SYSTEM INTO EXTRACTIVE CONTACT WITH THE HYDROCARBON PHASE THERIN; MAINTAINING THE EXTRACTION SYSTEM UNDER PRESSURE SUFFICIENT TO KEEP THE FLOWING CONTENTS LIQUID, AND MAINTAINING THE FLOWING CONTENTS OF THE EXTRACTION SYSTEM AT A TEMPERATURE ABOVE 40*C.; WITHDRAWING SUBSTANTIALLY AROMATIC-FREE AND GLYCOL-FREE RAFFINATE FROM THE SAME END OF THE SYSTEM AS THAT AT WHICH SOLVENT IS INTRODUCED; WITHDRAWING THE AROMATIC-RICH GLYCOLIC EXTRACT FROM THE OTHER END OF THE SYSTEM; PRESTRIPPING SAID EXTRACT UNDER EVAPORATIVE CONDITIONS TO LIBERATE THE MAJORITY OF ONLY THE MOST VOLATILE AROMATIC THEREFROM TOGETHER WITH NONAROMATICS OF EQUIVALENT VOLATILITY; CONDENSING THE SOLIBERATED VAPORS AND USING THE SO-CONDENSED MATERIAL AS THE SOLE HYDROCARBON REFLUX TO THE EXTRACTION SYSTEM; RETURNING SAID REFLUX TO THE EXTRACTION SYSTEM NEAR ITS SAID OTHER END; CONDUCTING THE REMAINDER OF THE EXTRACT TO A HEATED ZONE; STRIPPING THE REMAINING AROMATIC HYDROCARBONS FROM THE SOLVENT IN SAID ZONE; SUBJECTING THE SAID REMAINING AROMATIC HYDROCARBONS TO RECTIFICATION; WITHDRAWING THEM AS PRODUCT FROM THE SYSTEM; AND RETURNING THE SUBSTANTIALLY HYDROCARBON-FREE SOLVENT TO THE EXTRACTION SYSTEM.