Patent ID: 7114352

Claim:
Cryogenic air separation apparatus for producing elevated pressure nitrogen comprising: (A) a primary heat exchanger, a cryogenic air separation plant, and means for passing feed air to the primary heat exchanger and from the primary heat exchanger to the cryogenic air separation plant; (B) a product compressor having a plurality of stages, a turboexpander, means for passing nitrogen from the cryogenic air separation plant to the primary heat exchanger and from the primary heat exchanger to the product compressor, and means for passing nitrogen from the product compressor to the primary heat exchanger and from the primary heat exchanger to the turboexpander; (C) a booster compressor, means for passing nitrogen from the turboexpander to the primary heat exchanger and from the primary heat exchanger to the booster compressor, and means for passing nitrogen from the booster compressor to the product compressor; and (D) means for recovering elevated pressure nitrogen from the product compressor.