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

50 subject separation of paraffins from aromatics by

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Unformatted text preview: tion of the ether-free extract. Feed Solvent Extract Raffinate Ether-free F1 S E1 R1 Extract Amount, kg 100 120 133.4 86.6 16.1 Composition, wt%: Water 70 0 2.9 76.3 24.2 Acetic acid 30 0 9.1 20.6 75.8 Isopropyl ether 0 100 88.0 3.1 0.0 (b) In the diagram on the next page, the feed and solvent are represented by points F2 and S, respectively. The mixing point is M2, which is the sum of the feed and solvent (140 kg) with an overall composition of 37.1 wt% A, 34.3 wt% W, and 28.6 wt% E. A tie line passing through point M2 locates, on the equilibrium curve, the extract E2 and the raffinate R2. If the inverse lever arm rule is used to obtain E2 and R, and their compositions are read from the diagram, the following results are obtained: Feed Solvent Extract Raffinate F2 S E2 R2 Amount, kg 100 40 55.0 85.0 Composition, wt%: Water 48 0 9.3 50.5 Acetic acid 52 0 28.9 42.5 Isopropyl ether 0 100 61.8 7.0 Exercise 4.49 (continued) Exercise 4.50 Subject: Separation of paraffins from aromatics by liquid-liquid extraction with 90 mol% diethylene glycol (DEG) and 10 mol% water at 325oF and 300 psia. Given: 280 lbmol/h of 42.86 mol% nC6 , 28.57 mol% nC7 , 17.86 mol% benzene, and 10.71 mol% toluene. 500 lbmol/h of solvent solution. Assumptions: One equilibrium stage. UNIFAC L/L method for activity coefficients. Find: Flow rates and compositions of extract and raffinate phases. Selectivity of DEG. Analysis: Using the LLVF (three-phase flash) model of CHEMCAD, the result is: Flow rate, lbmol/h: Feed Solvent Extract Raffinate Diethylene glycol 0 450 447.5 2.5 Water 0 50 49.8 0.2 nC 6 120 0 18.7 101.3 nC 7 80 0 8.8 71.2 Benzene 50 0 31.6 18.4 Toluene 30 0 16.5 13.5 Total 280 500 572.9 207.1 DEG is more selective for aromatics. Exercise 4.51 Subject: Liquid-liquid extraction of organic acids from water with ethyl acetate (EA). Given: 110 lbmol/h of feed containing 5, 3, and 2 lbmol/h, respectively, of formic, acetic, and propionic acids in water. 100 lbmol/h of ethyl acetate solvent. One equilibrium stage. Assumptions: UNIFAC method for liquid-phase activity coefficients. T = 25oC. Find: Flow rates and compositions of extract and raffinate. Order of selectivity of EA. Analysis: Using the LLVF (three-phase flash) model of the CHEMCAD simulation program: Flow rate, lbmol/h: Feed Solvent Extract Raffinate Ethyl acetate 0 100 99.6 0.4 Water 100 0 14.7 85.3 Formic acid 5 0 2.1 2.9 Acetic acid 3 0 2.6 0.4 n-Propionic acid 2 0 1.9 0.1 Total 110 100 120.9 89.1 The order of selectivity is n-propionic acid highest, then acetic acid, and then formic acid. Exercise 4.52 Subject: Given: Leaching of oil from soybean flakes by a hexane solvent 100,000 kg/h of soybean flakes, containing 19% by weight oil. 200,000 kg/h of a hexane solvent. Oil content of the flakes to be reduced to 0.5 wt% in a single stage. Expected contents of the variable underflow in Example 4.9. Assumptions: Ideal leaching stage so that compositions of overflow and underflow liquids are equal. Find: Using an algebraic method, the compositions and...
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