Air seperation
AssigneeThe BOC Group, Inc.
InventorThomas Rathbone
Life of this patent
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Abstract
An air separation method and apparatus in which a flow of air is subjected to a first rectification so as to separate therefrom an oxygen fraction and a nitrogen fraction. An argon-containing stream comprising argon, oxygen, and, as an impurity, nitrogen is withdrawn from the first rectification and is subjected to a second rectification so as to separate an impure argon fraction containing nitrogen. Nitrogen impurity is stripped from a stream of the argon fraction in a stripping column. A stream of sub-cooled liquid cools a condenser associated with an upper region of the stripping column by indirect heat exchange with condensing argon-nitrogen vapor mixture, and passes out of said indirect heat exchange still in sub-cooled state.
Claims10
A method of separating air, comprising:
- subjecting a flow of air to a first rectification to thereby separate an oxygen fraction and a nitrogen fraction from the air and thereby to produce in a rectification column, a region having argon, oxygen and a nitrogen impurity;
- withdrawing from the region, an argon-containing stream comprising said argon, oxygen, and, nitrogen impurity;
- subjecting the argon-containing stream to a second rectification and thereby separating from it an impure argon fraction containing said nitrogen impurity;
- introducing a stream of the argon fraction into a stripping column and stripping said nitrogen impurity from said argon fraction, thereby to produce an argon-nitrogen vapour mixture;
- and
- condensing in a condenser, associated with an upper region of the stripping column, said argon-nitrogen vapour mixture by indirect heat exchange with a stream of sub-cooled liquid, the stream of sub-cooled liquid passing out of said indirect heat exchange remaining in a sub-cooled state.
An apparatus for separating air, comprising:
- a first rectification column for separating a flow of air into an oxygen fraction and nitrogen fraction;
- the first rectification column having an outlet for an argon-containing stream comprising argon, oxygen and, as an impurity, nitrogen;
- a second rectification column for separating from the argon-containing stream an impure argon fraction containing nitrogen;
- a stripping column for stripping nitrogen impurity from a stream of the impure argon fraction and having a condenser associated with an upper region of the stripping column;
- and
- a flow path through the condenser for a stream of sub-cooled liquid extending from a source of the sub-cooled liquid and returning to the source.
Dependencies are inferred from the claim text.