Separation of gaseous mixtures

Claim 1

METHOD OF SEPARATING GASEOUS MIXTURE INTO COMPONENT GASES IN A LOW TEMPERATURE FRACTIONATING OPERATION EMPLOYING A PLURALITY OF FRACTIONATING ZONES IN WHICH PRELIMINARY SEPARATION TAKES PLACE IN A FIRST FRACTIONATING ZONE UNDER SUPERATMOSPHERIC PRESSURE PRODUCING GASEOUS LOW BOILING POINT FRACTION AND LIQUID HIGH BOILING POINT FRACTION AND IN WHICH A FURTHER SEPARATION TAKES PLACE IN A SECOND FRACTIONATING ZONE UNDER RELATIVELY LOW PRESSURE PRODUCING GASEOUS LOW BOILING POINT COMPONENT AND LIQUID HIGH BOILING POINT COMPONENT, COMPRISING THE STEPS OF PROVIDING COLD GASEOUS MATERIAL UNDER SUPERATMOSPHERIC PRESSURE FROM COMPRESSED GASEOUS MIXTURE TO BE SEPARATED, THE GASEOUS MATERIAL INCLUDING COMPONENTS OF THE GASEOUS MIXTURE WITH THE PERCENTAGE OF HIGH BOILING POINT COMPONENT BEING LESS THAN THE PERCENTAGE OF HIGH BOILING POINT COMPONENT OF THE LIQUID HIGH BOILING POINT FRACTION AND GREATER THAN THE PERCENTAGE OF HIGH BOILING POINT COMPONENT OF THEFIRST GASEOUS LOW BOILING POINT FRACTION, PERFORMING A FIRST CONDENSING-EVAPORATING STEP INCLUDING ESTABLISHING HEAT INTERCHANGE B ETWEEN COLD GASEOUS MATERIAL AND LIQUID HIGH BOILING POINT COMPONENT TO VAPORIZE THE LIQUID HIGH BOILING POINT COMPONENT AND TOTALLY LIQUEFY THE COOL GASEOUS MATERIAL, THE FIRST CONDENSING-EVAPORATING STEP INCLUDING UTILIZATION OF VAPORIZED LIQUID HIGH BOILING POINT COMPONENT TO PROVIDE REBOIL FOR THE SECOND FRACTIONATING ZONE, ESTABLISHING THE QUANTITY OF LIQUID HIGH BOILING POINT COMPONENT AND OF THE GASEOUS MATERIAL HEAT EXCHANGED THEREWITH IN THE FIRST CONDENSING-EVAPORATING STEP TO PROVIDE A QUANTITY OF VAPORIZED LIQUID HIGH BOILING POINT COMPONENT AT LEAST SUFFICIENT TO SATISFY THE REBOIL REQUIREMENTS OF TH SECOND FRACTIONATING ZONE, REDUCING THE PRESSURE OF THE LIQUEFIED GASEOUS MATERIAL, INTRODUCING LIQUEFIED GASEOUS MATERIAL UNDER REDUCED PRESSURE INTO THE SECOND FRACTIONATING ZONE, PERFORMING A SECOND CONDENSING-EVAPORATING STEP INCLUDING ESTABLISHING HEAT INTERCHANGE BETWEEN GASEOUS LOW BOILING POINT FRACTION AND LIQUID MATERIAL OF THE OPERATION TO LIQUEFY GASEOUS LOW BOILING POINT FRACTION, THE LIQUID MATERIAL BEING FORMED IN A FRACTIONATING ZONE OPERATING UNDER LOW PRESSURE RELATIVE TO THE GASEOUS LOW BOILING POINT FRACTION AND INCLUDING COMPONENTS OF THE GASEOUS MIXTURE WITH THE PERCENTAGE OF HIGH BOILING POINT COMPONENT BEING GREATER THAN THE PERCENTAGE OF HIGH BOILING POINT COMPONENT OF THE LIQUID HIGH BOILING POINT FRACTION AND LESS THAN THE PERCENTAGE OF THE HIGH BOILING POINT COMPONENT OF THE SECOND LIQUID HIGH BOILING POINT FRACTION, AND UTILIZING LIQUEFIED LOW BOILING POINT FRACTION AS REFLUX FOR THE FIRST AND SECOND FRACTIONATING ZONES.