Distillation of light hydrocarbons

Claim 1

IN THE DISTILLATION OF A NORMALLY GASEOUS FEED MIXTURE OF HYDROCARBONS INCLUDING NORMALLY LIQUID HYDROCARBONS COMPRISING AT LEAST THREE HYDROCARBONS IN WHICH THE FEED MIXTURE IS INTRODUCED INTO A DISTILLATION ZONE AT A LOWER POINT THEREIN AND AN INTERMEDIATE BOILING HYDROCARBON ORIGINALLY PRESENT IN THE FEED MIXTURE IS SEPARATED FROM LOWER AND HIGHER BOILING HYDROCARBONS INCLUDING SAID NORMALLY LIQUID HYDROCARBONS AND IN WHICH A NORMALLY GASEOUS FACTION IS DISTILLED OVERHEAD THEREFROM, THE STEPS OF WITHDRAWING A SIDE STREAM OF SAID INTERMEDIATE HYDROCARBON FROM SAID DISTILLATION ZONE AT A POINT SUBSTANTIALLY ABOEE THE POINT OF INTRODUCTION OF SAID FEED MIXTURE, ADMIXING AT LEAST A PORTION OF SAID NORMALLY GASEOUS FRACTION WITH SAID FEED MIXTURE TO FORM A SECOND MIXTURE CONSISTING OF SAID GASEOUS FRACTION AND SAID FEED MIXTURE, SEPARATING SAID SECOND MIXTURE INTO A GASEOUS PHASE AND A LIQUID PHASE, WITHDRAWING SAID GASEOUS PHASE, AND DISTILLING SAID LIQUID PHASE TO OBTAIN SAID SIDE STREAM.