08 1452 336 kmolh the liquid rate below the feed stage

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Unformatted text preview: 119.08 kmol/h. The vapor rate in the stripping section = V' = V = 33.6 kmol/h = open steam flow rate. The bottoms rate = B = L' = 119.08 kmol/h. The mole fraction of isopropanol in the bottoms = 0.2/119.08 = 0.00168. The change to the part (a) McCabe-Thiele diagrams on the preceding page for the middle concentration region is extremely small because the location of the stripping section operating line changes only slightly. However, the change is important in the low-concentration region. The new McCabeThiele diagram for the low concentration region is shown below. The operating line for the stripping section has a slope of L'/V' = 119.08/33.6 = 3.54 and passes through the point {y = 0, x = 0.00168}. The number of stages remains about the same as for part (a). Thus, without a reboiler, use 15 equilibrium stages in the column. Exercise 7.33 (continued) Analysis: ( c) (continued) (c) The minimum number of stages is determined as shown in the McCabe-Thiele diagrams on the next page by stepping off stages between the equilibrium curve and the 45o line from xB = 0.0023 and xD = 0.675. The number of minimum equilibrium stages = just more than 8 equilibrium...
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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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