745 the distillation consists of an upper column uc

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Unformatted text preview: lower column (LC) operating at 4 to 5 atm. Compressed air, containing 79 mol% N2 is condensed to supply heat in the reboiler of LC, and then is fed as liquid air to an intermediate tray of LC. Bottoms liquid from LC, containing about 55 mol% N2, is the feed to an intermediate tray in UC. The reboiler of UC is the condenser for LC. Condensate from the top of LC is nearly pure N2, which is sent as reflux to the top of UC. The reboiler at the bottom of UC provides almost pure O2 boilup for UC. Nearly pure liquid O2 is withdrawn from the UC reboiler sump at the bottom of UC. The UC has no condenser. Nearly pure gaseous N2 leaves the top of UC. This is consistent with the fact that N2 with a normal boiling point of -195.8oC (77.4 K) is more volatile than O2 with a normal boiling point of -183oC (90.2 K). Assumptions: Constant molar overflow. Constant relative volatility at each pressure. Find: Construction lines on a McCabe-Thiele diagram that enable the determination of stage requirements. Analysis: In LC, the N2 composition ranges from 55 mol% at the bottom to about 99 mol% a...
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This note was uploaded on 09/08/2008 for the course CHE 244 taught by Professor Selebi during the Spring '06 term at Lehigh University .

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