Patent ID: 7421856
Filing Date: 2008-09-09
Classification: F25J,Y10S

Abstract:
1. A method for operating a cryogenic air separation plant having a higher pressure column and a lower pressure column comprising passing nitrogen vapor from the higher pressure column to the upper portion of a once-through main condenser, flowing oxygen liquid from the separation section of the lower pressure column to the upper portion of the once-through main condenser without recirculation of sump liquid from the lower pressure column to said upper portion during normal operation of the cryogenic air separation plant, passing the nitrogen vapor and the oxygen liquid down the once-through main condenser in heat exchange relation wherein at least some but not all of the downflowing oxygen liquid is vaporized such that the oxygen liquid and resulting oxygen vapor flows in a co-current direction toward a bottom portion of the once-through main condenser, and withdrawing both the oxygen vapor and oxygen liquid from the once-through main condenser from the bottom portion thereof in a liquid to vapor mass flowrate ratio within the range of from 0.05 to 0.5.