Separation of air

Claim 1

PROCESS FOR THE SEPARATION OF AIR TO PRODUCE A COMPRESSED GASEOUS OXYGEN FRACTION AND A GASEOUS NITROGEN FRACTION WHICH COMPRISES THE STEPS OF COMPRESSING THE AIR TO A RELATIVELY LOW PRESSURE, COOLING THE COMPRESSED AIR BY HEAT EXCHANGE WITH AT LEAST A PART OF AT LEAST ONE OF THE SEPARATION PRODUCTS, DIVIDING SAID COOLED AIR INTO A MAJOR AIR STREAM AND A MINOR AIR STREAM EXPANDING THE WHOLE OF SAID MAJOR AIR STREAM WITH THE PRODUCTION OF EXTERNAL WORK, WHEREBY AN AMOUNT OF COLD IS PRODUCED SUFFICIENT TO SATISFY THE GREATER PART OF THE COLD REQUIREMENTS OF THE PROCESS, COMPRESSING SAID MINOR AIR STREAM TO A RELATIVELY HIGH PRESSURE, COOLING THE WHOLE OF SAID COMPRESSED MINOR AIR STREAM BY HEAT EXCHANGE WITH A LIQUID OXYGEN FRACTION PUMPED UNDER THE PRESSURE, WHEREBY SAID LIQUID OXYGEN FRACTION IS VAPORIZED TO PRODUCE THE REQUIRED COMPRESSED GASEOUS OXYGEN FRACTION, EXPANDING SAID COOLED MINOR AIR STREAM, SUBJECTING SAID EXPANDED MAJOR AND MINOR AIR STREAMS TO RECTIFICATION TO SEPARATE THEREFROM A GASEOUS NITROGEN FRACTION AND A LIQUID OXYGEN FRACTION AND PUMPING SAID LIQUID OXYGEN FRACTION UNDER PRESSURE TO PRODUCE THE LIDUID OXYGEN FRACTION WHICH IS VAPORIZED BY HEAT EXCHANGE WITH THE COMPRESSED MINOR AIR STREAM.