Hydrocarbon separation

Claim 1

IN A PROCESS FOR THE PRODUCTION OF ETHYLENE IN WHICH A PRODUCT IS OBTAINED CONAINING ETHYLENE, METHANE AND HYDROGEN, THE METHOD OF REMOVING HYDROGEN AND METHANE FROM SAID MIXTURE WHICH COMPRISES PASSING SAID MIXTURE TO A FRACTION ZONE, WITHDRAWING A BOTTOMS FRACTION CONTAINING ETHYLENE FROM THE FRACTIONATION ZONE, WITHDRAWING A VAPOROUS OVERHEAD FRACTION FROM THE FRACTIONATION ZONE AT AN ELEVATED PRESSURE, COOLING AT LEAST A PORTION OF HTE WITHDRAWN OVERHEAD FRACTION WHEREBY IT IS PARTIALLY CONDENSED, PASSING THE COOLED OVERHEAD FRACTION TO A SEPARATION ZONE TO FORM A LIQUID PAHSE AND A VAPOR PHASE THEREIN, PASSING LIQUID FROM THE SEPARATION ZONE TO THE FRACTIONATION ZONE, WITHDRAWING A VAPOROUS FRACTION COMPRISING HYDROEN AND METHANE FROM THE SEPARATION ZONE AT AN ELEVATED PRESSURE, EXPANDING THE VAPOROUS FRACTION FORM THE SEPARATION ZONE THEREBY LOWERING ITS TEMPERATURE TO BELOW THAT OF THE VAPOROUS OVERHEAD FRACTION WITHDRAWN FROM THE FRACTIONATION ZONE, INDIRECTLY CONTACTING EXPANDED VAPORS OF THE SEPARATION ZONE WITH AT LEAST A PORTION OF THE VAPOROUS OVERHEAD FRACTION THEREBY COOLING AND PARTIALLY CONDENSING THE SAME, PASSING CONDENSATE THUS FORMED TO THE SEPARATION ZONE, PASSING LIQUID FROM THE SEPARATON ZONE TO A ZONE OF REDUCED PRESSURE WHEREBY SAID LIQUID IS PARTIALLY VAPORIZED AND COOLED TO BELOW THE TEMPERATURE OF THE VAPOROUS OVERHEAD FRACTION, INDIRECTLY CONTACTING THE THUS COOLED LIQUID WITH AT LEAST A PORTION OF THE VAPOROUS OVERHEAD FRACTION THEREBY COOLING AND PARTIALLY CONDENSING THE SAME AND PASSING CONDENSATE THUS FORMED TO THE SEPARATION ZONE.