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

For physical properties necessary to size the column

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Unformatted text preview: ft from the top of the packing. Reflux ratio = 5 and bottoms mole flow rate = 150 kmol/h Assumptions: Use 100 segments (called stages in the Chemsep program, when solving a packed column) to simulate each of the two sections of packing, with perfectly mixed vapor and liquid in each segment. Operation at about 75% of flooding. Find: The separation achieved. Analysis: The calculations were made with the Chemsep program. The properties chosen were: Gamma-Phi K model UNIFAC Activity coefficient Ideal gas law Equation of State DIPPR Vapour pressure Excess Enthalpy Other physical properties were by default with Wilke-Chang for liquid diffusivities. Bravo-Fair 1982 method for mass-transfer coefficients and interfacial area. Generalized pressure drop correlation of Leva for pressure drop. Newton's method to converge calculations with maximum of 10% change in vapor rate and 2oC change in temperature between iterations. Calculations converged in 11 iterations and 30 seconds with a Pentium 90 PC, giving the following distillate and bottoms compositions: Component Flow, kmol/h: Methanol Isopropanol Water Total: Feed Distillate Bottoms 100.0 50.0 100.0 250.0 90.00 9.91 0.08 99.99 10.00 40.09 99.92 150.01 Mole fraction: Methanol 0.4000 Isopropanol 0.2000 Water 0.4000 0.9000 0.0991 0.0008 0.0666 0.2672 0.6661 Back-calculated values of HETP ranged from about 1.5 to 3 ft for M and P, and 1.5 to 2 ft for W. Column diameter was computed to be 5.1 ft with a column pressure drop of 0.84 psi. Exercise 12.13 Subject: Separation of methanol (M) from a mixture containing isopropanol (P) and water (W) by distillation in a packed column with a structured packing, 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. Column contains 40 ft of structured packing in two sections (one above the feed and one below the feed). Feed entry is 25 ft from the top of the packing. Reflux ratio = 5 and bottoms mole flow rate = 150 kmol/h Assumptions: Use 100 segments (called stages in the Chemsep program, when solving a packed column) to simulate each of the two sections of packing, with perfectly mixed vapor and liquid in each segment. Operation at about 75% of flooding. Find: The separation achieved. Analysis: The calculations were made with the Chemsep program. The properties chosen were: Gamma-Phi K model UNIFAC Activity coefficient Ideal gas law Equation of State DIPPR Vapour pressure Excess Enthalpy Other physical properties were by default with Wilke-Chang for liquid diffusivities. Several different structured packings could used. Flexipac 2 in stainless steel was selected. Bravo-Rocha-Fair 1985 method for mass-transfer coefficients and interfacial area. Bravo-Rocha-Fair 1986 method for pressure drop. Newton's method to converge calculations with maximum of 10% change in vapor rate and 2oC change in temperature between iterations. Calculations converged in 10 iterations and 28 seconds with a Pentium 90 PC, giving the following d...
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