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

Therefore bottom pressure also 120 psia number of

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Unformatted text preview: and interheater stages as feed stages with heat transferred out as negative and heat transferred in as positive: Partial condenser and Top pressure = 250 psia No condenser or stage pressure drop. Therefore, bottom pressure also = 250 psia Number of stages = 17 (includes partial condenser and partial reboiler) Feed stage one = 5 from the top for the intercooler Feed stage two = 9 from the top for the feed to the column Feed stage three = 13 from the top for the interheater At the top, reflux rate = 150 lbmol/h At the bottom, bottoms rate = B = F - D = 100 - 23 = 77 lbmol/h Estimated distillate rate = 23 lbmol/h (actual rate) Estimated reflux rate = 150 lbmol/h (actual rate) Estimated temperature of stage 1 = 120oF Estimated temperature of bottom stage = 300oF Estimated temperature of stage 2 = 140oF Although the feed is given as a bubble-point liquid at 250 psia and 213.9oF, the SRK equation of state gave a bubble-point temperature of 210.7oF, which was the value used. Based on the feed composition below, the distillate rate of 23 lbmol/h corresponded 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: Condenser duty = 856,200 Btu/h Reboiler duty = 1,014,000 Btu/h o Top temperature = 115 F compared to assumed value of 120oF Bottom temperature = 264.4oF compared to assumed value of 300oF Stage 2 temperature = 123.7oF compared to assumed value of 140oF Exercise 10.23 (continued) Analysis: (continued) Analysis: (continued) Exercise 10.23 (continued) Exercise 10.24 Subject: Determination of optimal feed locations for two feeds of light normal paraffin hydrocarbon mixtures by a rigorous equilibrium-stage method. Given: Feeds of compositions below as a bubble-point liquids at a constant column pressure of 250 psia. Column has a partial condenser, partial reboiler, and 30 equilibrium stages in the column. Distillate rate = 36.0 lbmol/h and reflux rate = 150.0 lbmol/h. Peng-Robinson equation of state for K-values and enthalpies. Suggested feed locations are stage 15 (stage 17 from the top counting the partial condenser), and stage 6 (stage 26 from the top counting the partial condenser) from the bottom for the heaviest feed, F2. Peng-Robinson equation of state for Kvalues and enthalpies. Find: Optimal feed-stage locations. Analysis: The calculations were made with the TOWER model (Inside-out method) of the Chemcad program, with the following specifications: Partial condenser Top pressure = 250 psia No condenser or stage pressure drop. Therefore, bottom pressure also = 250 psia Number of stages = 32 (includes partial condenser and partial reboiler) Feed one initially to stage = 17 from the top Feed two initially to stage = 26 from the top At the top, reflux rate = 150 lbmol/h At the bottom, bottoms rate = B = F - D = 100 - 36 = 64 lbmol/h Estimated distillate rate = 36 lbmol/h (actual rate) Estimated reflux rate = 150 lbmol/h (actual rate) Estimated temperature of stage 1 = 120oF Estimated temperature of bottom stage = 250oF Estimated temperature of stage 2...
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This document was uploaded on 02/24/2014 for the course CBE 2124 at NYU Poly.

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