Refrigeration – Cryogenic treatment of gas or gas mixture – Separation of gas mixture
Reexamination Certificate
2006-06-09
2009-06-23
Doerrler, William C (Department: 3744)
Refrigeration
Cryogenic treatment of gas or gas mixture
Separation of gas mixture
C062S647000, C062S924000
Reexamination Certificate
active
07549301
ABSTRACT:
Argon, oxygen and nitrogen contained within an incoming air feed is fractionated within an air separation system having a multiple column arrangement that includes a higher pressure column and a lower pressure column to produce oxygen and nitrogen-rich fractions and an argon column to produce an argon-rich fraction for recovery of the argon as an argon product. A two-phase stream can be formed by either expanding at least part of a liquid air stream or by a liquid oxygen column bottoms formed within a higher pressure column of the multiple column arrangement. The liquid air stream is formed by liquefying part of the air feed to be fractionated against vaporizing a pumped liquid stream composed of nitrogen and/or oxygen. The diversion of the nitrogen vapor contained in the nitrogen-rich fraction increases the liquid to vapor ratio within the lower pressure column to increase the argon recovery.
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Doerrler William C
Praxair Technology Inc.
Rosenblum David M.
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