System and method for enhanced recovery of argon and oxygen from a nitrogen producing cryogenic air separation unit

An air separation unit comprising:

• a main air compression system configured for receiving a stream of incoming feed air and producing a compressed air stream;
• an adsorption based pre-purifier unit configured for removing water vapor, carbon dioxide, nitrous oxide, and hydrocarbons from the compressed air stream and producing a compressed and purified air stream, wherein the compressed and purified air stream is split into at least a boiler air stream and a turbine air stream;
• a distillation column system having a higher pressure column and a lower pressure column linked in a heat transfer relationship via a condenser-reboiler, the distillation column system further includes an argon column arrangement operatively coupled with the lower pressure column, the argon column arrangement having at least one argon column and an argon condenser;
• a main heat exchange system configured to cool the boiler air stream against a pumped oxygen stream received from the distillation column system to produce a cooled boiler air stream that is directed to the distillation column system and a gaseous oxygen product stream;
• a turboexpander arrangement configured to expand the turbine air stream to form an exhaust stream;
• the distillation column system is configured to receive the cooled boiler air stream and the exhaust stream and to produce a first oxygen enriched stream from the lower pressure column having a first oxygen concentration greater than or equal to 99.5 percent oxygen, a second oxygen enriched stream from the lower pressure column having a second oxygen concentration greater than 93 percent and lower than the first oxygen concentration, an oxygen enriched kettle stream from the bottom of the higher pressure column, and a nitrogen overhead stream from the lower pressure column;
• an oxygen pump configured to pump the first oxygen enriched stream or the second oxygen enriched stream to produce the pumped oxygen stream;
• wherein the argon column is configured to receive an argon-oxygen enriched stream from the lower pressure column and to produce a third oxygen enriched stream that is returned to or released into the lower pressure column and an argon-enriched overhead that is directed to the argon condenser;
• wherein the argon condenser is configured to condense the argon-enriched overhead against:
• (i) all or a portion of the first oxygen enriched stream from the lower pressure column, or (ii) all or a portion of the second oxygen enriched stream from the lower pressure column, to produce a crude argon stream, an argon reflux stream and an oxygen enriched waste stream;
• wherein the air separation unit is configured to produce one or more nitrogen products, the gaseous oxygen product stream, and the crude argon stream and wherein the argon recovery in the crude argon stream is greater than 30 percent of the argon contained in the compressed air stream.