Separation of gas mixtures

Claim 1

IN A PROCESS FOR SEPARATION OF A GAS MIXTURE INCLUDING A LOW BOILING COMPONENT AND A HIGH BOILING COMPONENT BY LIQUEFACTION AND FRACTIONATION IN A HIGH PRESSURE COLUMN AND A LOW PRESSURE COLUMN SEPARATE FROM THE HIGH PRESSURE COLUMN, COMPRISING (A) FRACTIONATING THE MIXTURE IN THE HIGH PRESSURE COLUMN TO PROVIDE AN OVERHEAD VAPOR RICH IN THE LOW BOILING COMPONENT AND AS BOTTOMS A CRUDE CUT OF THE HIGH BOILING COMPONENT IN LIQUID STATE; (B) CONDENSING A PORTION OF THE HIGH PRESSURE COLUMN OVERHEAD VAPOR AND USING THE RESULTING CONDENSATE AS REFLUX FOR THE HIGH PRESSURE COLUMN; (C) REDUCING THE PRESSURE OF CRUDE CUT AND CONDENSING THE REFLUX FOR THE HIGH PRESSURE COLUMN BY INDIRECT HEAT EXCHANGE OF CRUDE CUT AT THE REDUCED PRESSURE AND THE OVERHEAD VAPOR OF THE HIGH PRESSURE COLUMN;