Analysis d continued exercise 79 continued exercise

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Unformatted text preview: ued): Exercise 7.9 (continued) Exercise 7.10 Subject: Stage composition data for distillation of an A-B mixture. Given: Saturated liquid feed of 40 mol% A. Test results for vapor and liquid compositioins for 3 successive stages between the feed stage and a total condenser. ____________Mol % A_____________ Test 1 Test 2 Stage Vapor Liquid Vapor Liquid M+2 79.5 68.0 75.0 68.0 M+1 74.0 60.0 68.0 60.5 M 67.9 51.0 60.5 53.0 Assumption: Constant molar overflow. Find: Reflux ratio and overhead composition for each test. Analysis: Test 1: By material balance for component A around stage M + 1, Vy M + Lx M + 2 = Vy M +1 + Lx M +1 (1) Solving Eq. (1) for L/V and substituting for y and x values from above table, L y - yM 0.740 - 0.679 = M +1 = = 0.763 V x M + 2 - x M +1 0.680 - 0.600 From Eq. (7-7), reflux ratio = R = L/D = (L/V)/(1 - L/V) = 0.763/(1 - 0.763) = 3.22 D/V = (L/V)/(L/D) = 0.763/3.22 = 0.237. Noting that stages in the rectifying section are counted here from the bottom up instead of the top down, Eq. (7-5) becomes, L D y...
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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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