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Unformatted text preview: stages. Exercise 7.33 (continued)
Analysis: ( c) (continued) Exercise 7.33 (continued)
Analysis: ( c) (continued) Exercise 7.34
Subject: Stripping of isopropyl alcohol from water at 1 atm using either a partial reboiler or open (live) steam. Given: Bubble-point liquid feed containing 10 mol% alcohol. Vapor overhead to contain 40 mol% alcohol. Boilup, V/F = 0.246. Vapor-liquid equilibrium data from Exercise 7.33. Assumptions: Constant molar overflow. Find: Determine the number of equilibrium stages for: (1) Partial reboiler, (2) Open steam. Analysis: Take a basis of F = 100 kmol/h. Vapor rate leaving top of column = V = 0.246F = D = 0.246(100) = 24.6 kmol/h. Alcohol in overhead vapor = 0.4(24.6) = 9.84 kmol/h. Water in the overhead vapor = 24.6 - 9.84 = 14.76 kmol/h.
With a partial reboiler, bottoms rate = B = F - D = 100 - 24.6 = 75.4 kmol/h. Alcohol in bottoms = 10 - 9.84 = 0.16 kmol/h. Mole fraction of alcohol in bottoms = xB = 0.16/75.4 = 0.0021. With isopropanol as the most volatile component, the McCabe-Thiele diagram is...
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