Compositions of d and l1 for 4 stages in cascade b

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Unformatted text preview: D and L1 for 4 stages in cascade (b). Number of equilibrium stages for 50 mol alcohol in D of cascade (b). Analysis: From the given vapor-liquid equilibrium data, in the composition range of interest, ethyl alcohol is more volatile than water. Therefore, the y and x coordinates in a y-x plot pertain to ethyl alcohol. (a) Since L = 100 mol and V = 100 mol, the slope of the operating line from Eqs. (7-6) or (7-11) = L/V = 100/100 = 1. The terminal points on the operating line as (y, x) are: (?, 0.7) at the top and (0.3, ?) at the bottom. To determine the compositions of V4 and L1 for 4 stages, this operating line is located so that exactly 4 stages are stepped off in a y-x diagram, as shown below. From the diagram, the ethanol compositions are 76 mol% in V4 and 24 mol% in L1. Analysis: (continued) (b) It is impossible to obtain an overhead vapor with 85 mol% ethanol. With an infinite number of stages, the highest concentration of ethanol in the overhead vapor corresponds to that in equilibrium with the top liquid feed containing 70 mol% ethanol. From the given va...
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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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