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Unformatted text preview: l points on the operating line, because of the total condenser, as (y, x), are: (0.5, 0.5) at the top and (0.3, 0.1 ) at the bottom. However, point (0.3, 0.1) above the equilibrium line is impossible. Exercise 7.8 (continued) Exercise 7.9
Subject: Separation of air in a reboiled stripper Given: Reboiled stripper with total reboiler operating at 1 atm. Liquid air (79.1 mol% N2 and 20.9 mol% O2) fed to top stage. 60% of O2 in the feed is drawn off in vapor product from the reboiler. Bottoms vapor product contains 0.2 mol% N2. Vapor-liquid equilibria data are given. Assumptions: Feed is a saturated liquid. Find: (a) Mol% N2 in vapor from top stage. (b) Moles of vapor generated in reboiler per 100 moles of feed. (c) Number of equilibrium stages required. Analysis: (a) Take a basis of F = 100 mol/h. Therefore, 79.1 mol/h of N2 and 20.9 mol/h of O2 in the feed. Bottoms product vapor contains 0.6(20.9) = 12.54 mol/h of O2 and (0.2/99.8)(12.54) = 0.025 mol/h N2. By material balance, the overhead vapor contains 20.9 - 12.54 = 8.36 mol/...
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