Separation Process Principles- 2n - Seader & Henley - Solutions Manual

5 of the acetic acid analysis the extract model of

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Unformatted text preview: 0 psi. Number of stages = 7 plus a partial reboiler Feed to stage 1 At the top, no condenser At the bottom, bottoms flow rate = 99.33 lbmol/h Estimated distillate rate = 450 lbmol/h (actual rate = 551.59 - 99.33 = 452.26 lbmol/h) Estimated reflux rate = 550 lbmol/h Estimated temperature of stage 1 = 50oF Estimated temperature of bottom stage = 250oF Estimated temperature of stage 2 = 80oF Convergence was achieved in 4 iterations. The results are shown on the following two pages. The column feed is 14.5 mol% vaporized. The heat duty of the reboiler is 4.4674 MMBtu/h. The % stripping of each component in the feed is as follows: Component N2 C1 C2 C3 nC4 nC5 nC6 % Stripped 100.00 100.00 100.00 99.92 86.26 23.61 8.03 Exercise 10.41 (continued) Analysis: (continued) Analysis: (continued) Exercise 10.41 (continued) Exercise 10.42 Subject: Liquid-liquid extraction of a mixture of cyclohexane (1) and cyclopentane (2) with methanol (3). Given: Feed of 700 lbmol/h of cyclohexane and 300 lbmol/h of cyclopentane. Methanol solvent of 1,000 lbmol/h. Extractors with various numbers of equilibrium stages, operating at 25oC. Assumptions: Phase equilibria predicted by NRTL or UNIQUAC equations. Find: Product rates and compositions, and interstage flow rates and compositions for 1, 2, 5, and 10 equilibrium stages. Analysis: Reference 55 in Chap. 2 presents L/L equilibria data for the ternary system at 25oC (77oF). These data are fitted to the NRTL and UNIQUAC equations in "Liquid-Liquid Equilibrium Data Collection - Ternary Systems", Vol. V, Part 2 of the Chemical Data Series, by J. M. Sorenson and W. Arlt, DECHEMA (1980). Their fit to the simpler NRTL equation is almost as good as the UNIQUAC fit. Therefore, the NRTL equation is used here, with the following binary interaction parameters for use in the Chemcad program, where from Eq. (2-94), τ ij = I 1 1 2 J 2 3 3 gij − g jj RT = Bij BIJ -97.419 544.82 361.38 T , where T is in Kelvins BJI -56.868 318.02 234.33 αIJ 0.2 0.2 0.2 Using the Binodal Plot feature of the Chemcad program, a predicted ternary liquid-liquid equilibrium diagram is obtained, as shown on the next page, along with a corresponding table of predicted tie lines. It is seen that at 25oC, cyclopentane is completely soluble in methanol, but cyclohexane is only partially soluble in methanol. Is methanol a good solvent for the separation of cyclopentane from cyclohexane? From the slope of the tie lines, the answer is no; Cyclopentane distributes preferably to the cyclohexane-rich phase. For example, for one equilibrium stage, using the LLVF model of Chemcad, the following two liquid phases (raffinate and extract) are calculated when the given feed and solvent are mixed and brought to equilibrium at 25oC and 30 psia, where the pressure exceeds the bubble-point pressures of the feed (2.69 psia) and solvent (2.44 psia) so that a vapor phase does not form. Very little separation of (1) and (2) occurs. Exercise 10.42 (continued) Analysis: (continued) Analysis: (continued) Exercise 10.42 (continued) The Extract model of the Chemcad program was used to calcula...
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This document was uploaded on 02/24/2014 for the course CBE 2124 at NYU Poly.

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