Method for the production of air gases by the cryogenic separation of air with improved front end purification and air compression

A method for the production of air gases by the cryogenic separation of air with front end purification and air compression, the method comprising the steps of:

• a) compressing atmospheric air to a pressure suitable for the cryogenic rectification of air to produce a compressed wet air stream;
• b) purifying the compressed wet air stream of water and carbon dioxide within a front end purification system to produce a dry air stream having reduced amounts of water and carbon dioxide as compared to the compressed wet air stream, wherein the front end purification system comprises a first vessel and a second vessel configured in a permutable fashion, wherein the first vessel comprises a first adsorber and the second vessel comprises a second adsorber, wherein the first and second adsorbers operate in alternating cycles such that while the first adsorber is in an adsorption cycle, the second adsorber is in a regeneration cycle and while the second adsorber is in the adsorption cycle, the first adsorber is in the regeneration cycle;
• c) introducing the dry air stream to a cold box under conditions effective to separate the dry air stream into a nitrogen enriched stream and an oxygen enriched stream;
• and
• d) withdrawing the nitrogen enriched stream and the oxygen enriched stream from the cold box;
• wherein the regeneration cycle for each of the first and the second vessels of the front end purification system further includes the steps of:
• 1) depressurizing the first or second vessel from an adsorption pressure to a regeneration pressure that is sufficiently low to release water and carbon dioxide from a surface of an adsorbent material within the vessel;
• 2) regenerating the adsorbent material using a first dry gas;
• and
• 3) pressurizing the first or second vessel to the adsorption pressure using a second gas,
• wherein the second gas used in step 3) of the regeneration cycle is not sourced directly from the first or second vessel that is in the adsorption cycle,
• wherein the flow rate of the dry air stream introduced to the cold box remains substantially constant during step c).