Patent ID: 9222726
Filing Date: 2015-12-29
Classification: F25J

Abstract:
1. A method of separating air comprising: compressing and purifying the air such that a first compressed air stream and a second compressed air stream are produced, the second compressed air stream having a higher pressure than the first compressed air stream; cooling at least part of the first compressed air stream and condensing the second compressed air stream through indirect heat exchange with return streams produced by a distillation column system to form a liquid air stream; producing a refrigerant stream and imparting refrigeration with the use of the refrigeration stream into the distillation column system; introducing the at least part of the first compressed air stream into a higher pressure column of the distillation column system, the distillation column system also having a lower pressure column operatively associated with the higher pressure column in a heat transfer relationship, a crude argon column connected to the lower pressure column to rectify an argon-oxygen containing vapor stream withdrawn from the lower pressure column to thereby, at least in part, produce a crude argon stream and an argon refining column to rectify the crude argon stream and thereby form an argon product stream from an argon-rich liquid column bottoms produced in the argon refining column; reboiling the argon refining column in a bottom reboiler of the argon refining column with the at least a portion of liquid air stream to produce a subcooled liquid air stream; dividing the subcooled liquid air stream from the bottom reboiler of the argon refining column into a first intermediate reflux stream and a second intermediate reflux stream; valve expanding the first intermediate reflux stream and the second intermediate reflux stream; introducing the first intermediate reflux stream into an intermediate location of the higher pressure column; and introducing, the second intermediate reflux stream into the lower pressure column at a level thereof above where all or any part of a crude liquid oxygen stream composed of a crude liquid oxygen column bottoms of the higher pressure column is introduced for further refinement.