Extractive distillation process for the purification of ethanol

Claim 1

IN A METHOD FOR PURIFYING AND REFINING CRUDE AQUEOUS ETHANOL PRODUCED BY THE HYDRATION OF ETHYLENE, SAID CRUDE ETHANOL CONTAINING LOWER BOILING IMPURITIES, INCLUDING DIETHYL ETHER, AND HIGHER BOILING IMPURITIES, INCLUDING MALODOROUS ORGANIC IMPURITIES BOILING BOTH ABOVE AND BELOW ETHANOL, AND UNSTABLE POLYMERIC OILS WHICH UNDERGO DECOMPOSITION UNDER NORMAL DISTILLATION CONDITIONS, WHICH COMPRISES THE STEPS OF CONTINUOUSLY PASSING SAID CRUDE AQUEOUS ETHANOL INTO A FRACTIONAL EXTRACTIVE DISTILLATION ZONE. CONTINUOUSLY FEEDING WATER INTO SAID FRACTIONAL EXTRACTIVE DISTILLATION ZONE AT A POINT ABOVE THE AQUEOUS ETHANOL FEED STREAM, MAINTAINING AN INTERNAL LIQUID REFLUX HAVING AN ETHANOL CONTENT OF 5 TO 40 WEIGHT PERCENT WITHIN THE ZONE BELOW THE WATER FEED POINT CONTINUOUSLY REMOVING FROM THE UPPER PORTION OF SAID EXTRACTIVE DISTILLATION ZONE, A STREAM CONTAINING ORGANIC IMPURITIES INCLUDING BOTH LOWER AND HIGHER BOILING MATERIALS, CONTINUOUSLY REMOVING FROM THE LOWER PORTION OF SAID EXTRACTIVE DISTILLATION ZONE A DILUTE AQUEOUS ETHANOL STREAM, PASSING SAID AQUEOUS ETHANOL STREAM TO A CONCENTRATING, FRACTIONAL DISTILLATION ZONE, AND REMOVING FROM AN UPPER PORTION OF SAID CONCENTRATING DISTILLATION ZONE A STREAM OF PARTIALLY PURIFIED ETHANOL, THE IMPROVEMENT WHICH COMPRISES THE STEPS IN COMBINATION OF INITIALLY PASSING SAID CRUDE AQUEOUS ETHANOL INTO A FRACTIONAL DISTILLATION ZONE, REMOVING FROM THE UPPER PORTION OF SAID ZONE A STREAM CONTAINING LOWER BOILING IMPURITIES INCLUDING SUBSTANTIALLY ALL OF THE DIETHYL ETHER, REMOVING FROM THE LOWER PORTION OF SAID ZONE A LIQUID AQUEOUS ETHANOL STREAM, CONTINUOUSLY PASSING THE ETHER-FREE AQUEOUS ETHANOL STREAM INTO A PHASE SEPARATION ZONE WHEREIN PHASE SEPARATION TAKES PLACE, SEPARATING A NON-AQUEOUS UPPER LAYER CONTAINING A MAJOR PORTION OF THE ORGANIC MALODOROUS IMPURITIES, SEPARATING AN AQUEOUS ETHANOL LOWER LAYER,CONTINUOUSLY PASSING SAID AQUEOUS ETHANOL STREAM INTO THE ABOVE DESCRIBED FRACTIONAL EXTRACTIVE DISTILLATION ZONE, AFTER REMOVAL FROM THE ABOVE DESCRIBED CONCENTRATING FRACTIONAL DISTILLATION ZONE OF A STREAM OF PARTIALLY PURIFIED ETHANOL, SUBSEQUENTLY PASSING SAID STREAM OF PARTIALLY PURIFIED ETHANOL INTO A STRIPPING FRACTIONATION ZONE, CONTINUOUSLY REMOVING FROM AN UPPER PORTION OF SAID STRIPPING FRACTIONAL ZONE AT LEAST 0.5 WEIGHT PERCENT AND NOT MORE THAN 10 WEIGHT PERCENT OF SAID FEED STREAM INCLUDING ESSENTIALLY ALL OF THE VOLATILE IMPURITIES, AND INCLUDING ALL OF THE MALODOROUS IMPURITIES, AND REMOVING FROM THE LOWER PORTION OF SAID STRIPPING FRACTIONATION ZONE, A STREAM OF PURIFIED ODOR-FREE ETHANOL.