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

Therefore bottom pressure also 1 atm number of stages

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Unformatted text preview: = 140oF Based on the feed compositions below, the distillate rate of 36 lbmol/h corresponds to a desired split between propane and n-butane. The calculations converged rapidly in 3 outer-loop iterations with results given below and on the following pages. The separation with feed stages at 12 and 15 from the top is much better than the separation with feed stages at 17 and 26. For the better stage locations: Top temperature = 118.3oF compared to assumed value of 120oF Bottom temperature = 252.8oF compared to assumed value of 300oF Analysis: (continued) Exercise 10.24 (continued) Exercise 10.25 Subject: Distillation of a hydrocarbon mixture and comparison with solution in Perry's Handbook. Given: Bubble-point liquid feed of composition given below. Column has partial condenser, partial reboiler, and 9 equilibrium stages in the column, with operation at 120 psia. Reflux rate = 126.1 lbmol/h and vapor distillate rate = 48.9 lbmol/h. Grayson-Streed correlation for K-values and Redlich-Kwong equation of state for enthalpies. Find: Product compositions, stage temperatures, interstage flow rates and compositions, reboiler duty, and condenser duty. Analysis: The calculations were made with the TOWER model (Inside-out method) of the Chemcad program, with the following specifications: Partial condenser Top pressure = 120 psia No condenser or stage pressure drop. Therefore, bottom pressure also = 120 psia Number of stages = 11 (includes partial condenser and partial reboiler) Feed stage = 6 from the top At the top, reflux rate = 126.1 lbmol/h At the bottom, bottoms rate = B = F - D = 100 - 48.9 = 51.1 lbmol/h Estimated distillate rate = 48.9 lbmol/h (actual rate) Estimated reflux rate = 126.1 lbmol/h (actual rate) Estimated temperature of stage 1 = 120oF Estimated temperature of bottom stage = 250oF Estimated temperature of stage 2 = 140oF The feed is given as a bubble-point liquid at 120 psia. Using the Grayson-Streed correlation, the temperature is computed to be 180.8oF. Based on the feed composition below, the distillate rate of 48.9 lbmol/h corresponds to a desired split between n-butane and isopentane. The calculations converged rapidly in 3 outer-loop iterations with results given below and on the following pages. Condenser duty = 1,002,600 Btu/h Reboiler duty = 1,427,000 Btu/h Top temperature = 161.4oF compared to assumed value of 120oF Bottom temperature = 230.0oF compared to assumed value of 250oF Stage 2 temperature = 173.9oF compared to assumed value of 140oF Analysis: (continued) Exercise 10.25 (continued) Analysis: (continued) Exercise 10.25 (continued) Exercise 10.25 (continued) Analysis: (continued) The above results for the product compositions are compared to the results in Perry's Handbook as follows: Component Propane Isobutane n-Butane Isopentane n-Pentane Total: Feed, lbmol/h 5.00 15.00 25.00 20.00 35.00 100.00 Perry's Handbook: Distillate, Bottoms, lbmol/h lbmol/h 5.00 0.00 14.82 0.18 23.60 1.40 3.21 16.79 2.30 32.70 48.93 51.07 This exercise: Distillate, Bottoms, lbmol/h lbmol/h...
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