Patent ID: 7437890

Claim:
A method for the cryogenic separation of air comprising: (A) compressing a first feed air stream to a first pressure, cooling the compressed first feed air stream, turboexpanding the cooled compressed first feed air stream, and passing the turboexpanded first feed air stream into a cryogenic air separation plant comprising at least one column; (B) compressing a second feed air stream to a second pressure, condensing the compressed second feed air stream, and passing the condensed compressed second feed air stream into the cryogenic air separation plant; (C) condensing a third feed air stream at a pressure less than the first pressure and passing the condensed third feed air stream into the cryogenic air separation plant; (D) separating the feed air by cryogenic rectification within the cryogenic air separation plant to produce a product comprising liquid oxygen and pumping the liquid oxygen to produce a pressurized liquid oxygen stream; and (E) vaporizing the pressurized liquid oxygen stream by passing the pressurized liquid oxygen stream in indirect heat exchange with the second feed air stream and the third feed air stream, thereby causing the condensation of the second feed air stream and the third feed air stream.