Process for producing oxygen

Claim 1

A PROCESS FOR PRODUCING OXYGEN BY THE LIQUEFACTION AND RECTIFICATION OF AIR WHICH COMPRISES PASSING A STREAM OF AIR THROUGH A PATH IN A HEAT EXCANGE ZONE, PASSING A STREAM OF NITROGEN RECTIFICATION PRODUCT THROUGH ANOTHER PATH IN SAID HEAT EXCHANGE ZONE IN HEAT EXCHANGE RELATION WITH THE AIR PASSING THERETHROUGH, THEREBY, COOLING THE AIR TO A TEMPERATURE CLOSE TO ITS CONDENSATION POINT AT A TEMPERATURE PREVAILING IN SAID HEAT EXCHANGE ZONE AND EFFECTING SUBSTANTIALLY COMPLETE REMOVAL OF CARBON DIOXIDE FROM THE AIR IN ITS PASSAGE THROUGH SAID HEAT EXCHANGE ZONE, WARNING A MINOR PORTION OF THE THUS CHILLED AIR TO A TEMPERATURE SUCH THAT UPON SUBSEQUENT EXPANSION SUBSTANTIALLY NONE OF THE EXPANDED AIR IS LIQUIFIED, EXPANDING THE WARMED PORTION OF THE AIR TO PRODUCE REFRIGERATION IN AMOUNT SUFFICIENT TO COMPENSATE FOR COLD LOSSES RESULTING FROM THE DIFFERENCE IN ENTHALPY BETWEEN THE INCOMING AIR AND THE OUTGOING PRODUCTS OF RECTIFICATION AND FOR HEAT LEAKS INTO THE PROCESS, PASSING THE REMAINDER OF THE AIR AT SAID TEMPERATURE CLOSE T ITS CONDENSATION POINT TO A RECTIFICATION ZONE, MAINTAINING THE TEMPERATURE DIFFERENCE BETWEEN THE TEMPERATURE OF THE AIR LEAVING AND THE TEMPERATURE OF THE NITROGEN RECTIFICATION PRODUCT ENTERING SAID ZONE SO THAT IT FALLS WITHIN THE RANGE OF ABOUT 6* TO ABOUT 8* F. AND PERIODICALLY REVERSING THE FLOW OF AIR AND NIREOGEN RECTIFICATION PRODUCT THROUGH THEIR RESPECTIVE PATHS IN SAID ZONE, WHEREBY UPON EACH OF SAID REVERSALS THE NITROGEN RECTIFICATION PRODUCT SUBSTANTIALLY COMPLETELY REMOVES THE CARBON DIOXIDE DEPOSITED IN SAID ZONE DURING THE PRECEDING STEP OF SAID PROCESS.