75 xb b from the reflux ratio l 3d v l d 4d

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Unformatted text preview: the reflux ratio, L = 3D, V = L + D = 4D. Therefore, D/V = 1/4 and L/V =3/4. Use a subscript of D for distillate, R for reflux, B for streams leaving the reboiler, and 1 for the theoretical plate, when used. With 1 theoretical plate, from part (a), y1 = 0.75 xD = 0.75 x1 = 0.545 Benzene material balance around plate 1, y BV + x D L = y1V + x1 L (3) Solving for yB L 3 y B = y1 + ( x1 - x D ) = 0.750 + (0.545 - 0.750) = 0.596 V 4 Analysis: (b) (continued) Exercise 7.12 (continued) The mole fraction of benzene in the bottoms product is in equilibrium with yB =0.596. Therefore, the form of Eq. (2) applies, yB 0.596 xB = = = 0.371 y B + (1 - y B ) 0.596 + 2.5(1 - 0.596) Overall total material balance, F = 100 = D + B (4) Overall benzene material balance, xFF = xDD + xBB or 50 = 0.75D + 0.371B (5) Solving Eqs. (4) and (5), D = 34.2 moles or 34.2 mol/100 mol feed, and B = 65.8 moles. (c) With the feed to the theoretical plate, the following results apply from part (b), y1 = 0.75 xD = 0.75 x1 = 0...
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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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