18 continued analysis continued b f feed rate l

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Unformatted text preview: (b) F = Feed rate = L = 1.25(100) = 125 kmol/h. V = Vapor rate = 100 kmol/h. Therefore, with no condenser and constant molar overflow, B = F -V = 125 - 100 = 25 kmol/h. The slope of the stripping section operating line = L / V = 125/100 = 1.25. The q-line is vertical for a saturated liquid feed, passing through xF = 0.36. The stripping section operating line is positioned by trial and error so that 8 + 1 equilibrium stages will be stepped off. Because part (a) shows that a very low mole fraction of benzene is obtained in the bottoms, it is suspected that the operating line will intersect the 45o line almost at the origin. If this were true, then the operating line, with a slope of 1.25, would intersect the vertical q-line at 1.25(0.36) = 0.45. Use this as a first approximation and adjust it downward until only 9 stages can be stepped off. The final result is shown in the two plots on the next page, where the second plot is for the low concentration region. As seen, the mole percent of benzen...
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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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