Methods for separating mixtures of normally gaseous materials

Claim 1

A LOW TEMPERATURE PROCESS FOR SEPARATING COMPONENTS OF A GASEOUS MIXTURE INCLUDING A RELATIVELY LOWER BOILING, NORMALLY GASEOUS FIRST COMPONENT, A RELATIVELY INTERMEDIATE BOILING, NORMALLY GASEOUS SECOND COMPONENT AND A RELATIVELY HIGHER BOILING, NORMALLY GASEOUS THIRD COMPONENT, COMPRISING (A) COOLING AND PARTIALLY CONDENSING COMPRESSED GASEOUS MIXTURE TO FORM A FIRST VAPOR PORTION RICH IN FIRST COMPONENT AND CONTAINING SECOND AND THIRD COMPONENTS AND A FIRST LIQUID PORTION RICH IN SECOND COMPONENT AND CONTAINING THIRD COMPONENT, (B) SEPARATING THE FIRST VAPOR PORTION FROM THE FIRST LIQUID PORTION TO PROVIDE A FIRST VAPOR AND A FIRST LIQUID CONDENSATE, (C) PASSING SEPARATED FIRST VAPOR IN HEAT EXCHANGE RELATIONSHIP WITH LIQUID IN AN EVAPORATION ZONE TO FURTHER COOL AND PARTIALLY CONDENSE SEPARATED FIRST VAPOR TO FORM A SECOND VAPOR PORTION RICH IN FIRST COMPONENT AND A SECOND LIQUID PORTION RICH IN SECOND COMPONENT AND CONTAINING FIRST AND THIRD COMPONENTS, (D) SEPARATING THE SECOND VAPOR PORTION FROM THE SECOND LIQUID PORTION TO PROVIDE A SECOND VAPOR AND A SECOND LIQUID CONDENSATE, (E) WITHDRAWING SEPARATED SECOND VAPOR AS PRODUCT, (F) PARTIALLY VAPORIZING SEPARATED SECOND LIQUID CONDENSATE TO OBTAIN A THIRD VAPOR PORTION RICH IN FIRST COMPONENT AND A REMAINING LIQUID PORTION RICH IN SECOND COMPONENT AND CONTAINING THIRD COMPONENT, (G) SEPARATING UNDER SUPERATMOSPHERIC PRESSURE THE THIRD VAPOR PORTION FROM THE REMAINING LIQUID PORTION TO OBTAIN A THIRD VAPOR AND A REMAINING LIQUID, (H) PASSING REMAINING LIQUID IN THE EVAPORATION ZONE, (I) MAINTAINING LIQUID IN THE EVAPORATION ZONE UNDER SUBATMOSPHERIC PRESURE, LIQUID IN THE EVAPORATION ZONE BEING PARTIALLY VAPORIZED BY HEAT EXCHANGE WITH SEPARATED FIRST VAPOR TO PROVIDE A FOURTH VAPOR RICH IN SECOND COMPONENT, AND (J) WITHDRAWING FOURTH VAPOR RICH IN SECOND COMPONENT AS PRODUCT FROM THE EVAPORATION ZONE TO LEAVE A LIQUID RESIDUE CONTAINING THIRD COMPONENT.