Production of oxygen by liquefaction and rectification of air

Claim 1

A PROCESS FOR PRODUCTING OXYGEN BY THE LIQUEFACTION AND RECTIFICATION OF AIR IN A RECTIFICATION SYSTEM INVOLVING LOW AND HIGH PRESSURE STAGES, WHICH COMPRISES PASSING A STREAM OF AIR UNDER PRESSURE THROUGH A PATH IN A REVERSING EXCHANGER TO RECOVER THE COLD CONTENT OF AN OUTGOING PRODUCT OF RECTIFICATION AND THUS COOL THE AIR TO A TEMPERATURE CLOSE TO ITS CONDENSATION POINT, PERIODICALLY REVERSING THE FLOW OF AIR AND RETIFICATION PRODUCT THROUGH THEIR RESPECTIVE PATHS IN THE REVERSING EXCHANGER SO THAT UPON EACH OF SAID REVERSALS THE RECTIFICATION PRODUCT SUBSTANTIALLY COMPLETELY REMOVES THE CARBON DIOXIDE DEPOSITED IN THE REVERSING EXCHANGER DURING THE PRECEDING STEP OF THE PROCESS, PASSING THE THUS COOLED AIR THROUGH A BODY OF CRUDE LIQUID OXYGEN IN THE HIGH PRESSURE STAGE OF THE RECTIFICATION SYSTEM THUS SCRUBBING SAID THUS COOLED AIR WITH SAID CRUDE LIQUID OXYGEN, WITHDRAWING A MINOR PORTION OF THE CRUDE LIQUID OXYGEN-SCRUBBED AIR, WARMING THE WITHDRAWN MINOR PORTION BY INDIRECT HEAT EXCHANGE WITH A STREAM PASSING THROUGH SAID REVERSING EXCHANGER TO A TEMPERATURE SUCH THAT NO LIQUEFACTION OF SAID WITHDRAWN MINOR PORTION TAKES PLACE UPON ITS EXPANSION, EXPANDING THE THUS WARMED PORTION, INTRODUCING THE EXPANDED PORTION INTO THE LOW PRESSURE STAGE, PURIFYING THE CRUDE LIQUID OXYGEN BY FILTERING OUT CARBON DIOXIDE PARTICLES AND ABSORBING DISSOLVED ACETYLENE THEREFROM, AND INTRODUCING THE THUS PURIFIED CRUDE LIQUID OXYGEN INTO THE LOW PRESSURE STAGE FOR FURTHER RECTIFICATION.