Retrofittable argon recovery improvement to air separation
OwnerDonald C. Ericksoninventor
Life of this patent
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Abstract
The argon recovery of an air distillation plant is increased by increasing the argon rectifier reboil and simultaneously decreasing the nitrogen stripping reboil. No additional power and minimal added equipment is required. Referring to FIG. 1, two separate argon rectifier reflux condensers (7 and 9) are provided, either for a single argon rectifier or optionally as shown for two separate argon rectifiers (12 and 13). Kettle liquid is partially evaporated in reflux condenser 7 and the liquid residue is further evaporated in reflux condenser 9 to a vapor of differing (higher) O.sub.2 content. The two vapor stream are separately fed to different heights of column 2, separated by countercurrent contact zone 11.
Claims20
A process for distilling air to produce argon and oxygen of at least 98% purity comprising:
- (a) rectifying at least part of the pressurized supply air to kettle liquid and liquid N.sub.2 ;
- (b) partially evaporating at least part of the kettle liquid at reduced pressure by exchanging latent heat with crude argon vapor;
- (c) separately at least partially evaporating at least part of the liquid remnant from said first partial evaporation step by exchanging latent heat with crude argon vapor;
- (d) separately feeding two vapor streams produced from steps (b) and (c) to separate heights of a nitrogen removing distillation column;
- and
- (e) rectifying an oxygen-argon mixture from said distillation column to produce quality crude argon by refluxing said rectification step with both of the liquid crude argon streams produced by steps (b) and (c).
Apparatus for distilling from air oxygen of at least 98% purity and also argon comprising:
- (a) a rectification column for at least part of the supply air which produces an oxygen enriched liquid bottom product.
- (b) a first reflux condenser in which at least part of said rectifier bottom liquid is partially evaporated;
- (c) a second reflux condenser in which at least part of the unevaporated liquid from said first reflux condenser is evaporated;
- (d) a nitrogen-removing distillation column including at least two separate vapor feedpoints separated by a zone of countercurrent vapor-liquid contact;
- and
- (e) separate conduits for routing vapor from said first reflux condenser to the higher of said feedpoints and vapor from said second reflux condenser to the lower of said feedpoints.
Process for increasing the argon recovery capability of a dual pressure cryogenic air distillation plant incorporating a supply air rectifier, a nitrogen removal column, and at least one argon rectifier, comprising:
- (a) providing two argon rectifier overhead reflux condensers;
- (b) routing air rectifier bottom liquid to the first condenser and partially evaporating it;
- (c) evaporating at least part of the unevaporated effluent from said first condenser in said second condenser;
- (d) routing the vapor from said first condenser to said nitrogen removal column;
- and
- (e) separately routing the vapor from said second condenser to a lower height of said nitrogen removal column.
Dependencies are inferred from the claim text.