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

0317 00314 00313 00313 00314 mole fraction of n2 in

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Unformatted text preview: istillate and bottoms compositions: Component Flow, kmol/h: Methanol Isopropanol Water Total: Feed Distillate Bottoms 100.0 50.0 100.0 250.0 90.09 8.89 0.02 100.00 8.91 41.11 99.98 150.00 Mole fraction: Methanol 0.4000 Isopropanol 0.2000 Water 0.4000 0.9109 0.0889 0.0002 0.0594 0.2740 0.6666 Back-calculated values of HETP ranged from about 1.3 to 2 ft for M and P, and 1.1 to 1.4 ft for W. Column diameter was computed to be 5.1 ft with a column pressure drop of 0.43 psi. Exercise 12.14 Subject: Separation of a mixture of methanol (M) from a mixture containing isopropanol (P) and water (W) by distillation in a sieve-tray column for various conditions of % flood, weir height, and % hole area, using a rate-based method. Given: A bubble-point feed of 100 kmol/h of M, 50 kmol/h of P, and 100 kmol/h of W at 1 atm is sent to tray 25 from the top tray of a column containing 40 trays, operating at 1 atm. Reflux ratio is 5 and bottoms mole flow rate = 150 kmol/h. Use UNIFAC method for liquid-phase activity coefficients and the Chan-Fair method for mass-transfer coefficients and interfacial area. Consider combinations of: 80%, 60%, and 40% of flooding. 3, 2, and 1 inch weir heights. 14%, 10%, and 6% hole area. Assumptions: Assume both phases are perfectly mixed on each tray. Find: The separations achieved. Analysis: The Chemsep method is applied with the Simple Distillation option, a total condenser, a partial reboiler, and 42 stages (counting the condenser and the reboiler). Thus, the feed is sent to stage 26 from the top. To estimate K-values from the UNIFAC method, the ideal gas law is assumed with DIPPR vapor pressure, and excess enthalpy for the liquid phase. For physical properties necessary to size the column diameter and compute mass-transfer coefficients and interfacial area, the following options were chosen: Rackett equation for liquid density. Wilke and DIPPR for vapor viscosity. Molar averaging of DIPPR pure component liquid viscosity, vapor thermal conductivity, liquid thermal conductivity, and surface tension. Binary liquid diffusivities from Wilke-Chang method. Neglect pressure drop. Automatic initialization. Newton's method, but maximum change of liquid or vapor flow rate of only 10% and maximum temperature change of only 2oC. It was found that the % hole area had a negligible effect on the purity of methanol in the distillate. Therefore, only combinations of % flood and weir height are reported here. The separations achieved are given below in terms of the methanol purity in the distillate in mole%. % Flood 80 80 80 60 60 60 40 40 40 Weir height, in. 1 2 3 1 2 3 1 2 3 Mole % M in distillate 90.54 90.76 90.86 90.03 90.34 90.71 89.32 89.81 90.17 For this problem, the separation achieved is not significantly affected by the % flood or weir height. Exercise 12.15 Subject: Effect of % flood on the Murphree efficiency for oxygen and the separation of air in the upper column of an air separation system, using a rate-based method. Given: A sieve-tray column with 48 plates, no condenser, and a split reboiler that gives 50 mol% liquid bottoms and 50 mol% vapor bottoms. A feed at 80 K, 131.7 kPa, and 1349 lbmol/h, with a composition of 97.868 mol% N2, 0.365 mol% A, and 1.767 mol% O2, entering the top tray. A feed at 83 K, 131.7 kPa, and 1832 lbmol/h,...
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This document was uploaded on 02/24/2014 for the course CBE 2124 at NYU Poly.

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