Patent ID: 11933539
Assignee: PRAXAIR TECHNOLOGY, INC.
Field: Chemical engineering (Chemistry)
Classification: CPC F | IPC F

Claim 9:
10. A method for increasing the argon recovery in an oxygen, nitrogen, and argon producing air separation unit, the air separation unit configured to receive an incoming feed air stream and produce an oxygen product stream, a nitrogen product stream, and an argon stream, the air separation unit having a main air compression circuit, a main heat exchanger, and a distillation column system having a higher pressure column and a lower pressure column linked in a heat transfer arrangement via a main condenser-reboiler, an argon column configured for receiving an argon-oxygen containing stream from the lower pressure column and an argon condensing arrangement configured for condensing an argon-rich vapor stream from the argon column against an oxygen containing condensing medium, the method comprising the steps of:
(a) directing a first portion of a boil-off vapor stream exiting an argon condensing arrangement to the lower pressure column of the distillation column system;
(b) recycling a second portion of the boil-off vapor stream exiting the argon condensing arrangement to the main air compression circuit;
(c) mixing or blending the second portion of the boil-off vapor stream exiting the argon condensing arrangement with the incoming feed air stream;
wherein the recycled second portion of the boil-off vapor stream exiting the argon condensing arrangement is preferably between about 5.0% and about 12.0% of the flow of the incoming feed air stream.