Distillation Column

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Distillation Column

• By Jesse Reeves

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Outline

• Where we are, where we want to be.
• How to get there.
• What we used and what we got.
• The trouble.
• The model.

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What we have

• 12 tray bubble-cap distillation column
• Isoproply alcohol water separation

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What we want

• Same distillation column
• Ethanol water separation

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How to get there

• Operate column at total reflux
• Determine stage efficiency
• Model the column in Aspen
• Compare Aspen model to real IPA separation
  results
• Apply the Aspen model to an Ethanol separation

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Theory to get there
Equilibrium curve Stripping operating line
Rectifying operating line Murphree-vapor efficiency
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Theory in a graph
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The Column
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The Data
Calibration
Stage State Method MassIPA Error y Mass Ave Error Emv eq Error
2 Liquid Pycnometer 83.2014 2.7145 85.0 2.5    
3 Liquid Pycnometer 81.4879 2.9938 84.0 2.5 68.2106 192.6003
4 Liquid Pycnometer 78.4166 2.6494 83.0 2.5 67.0089 102.1962
5 Liquid Pycnometer 81.6113 2.7021 84.0 2.5 -133.7437 -259.9631
6 Liquid Pycnometer 77.0589 2.5954 82.0 2.5 92.1339 101.3146
7 Liquid Pycnometer 54.8630 2.1294 79.0 2.5 91.9579 18.7079
8 Liquid Pycnometer 53.5125 2.1461 79.0 2.5 5.2986 11.8814
9 Liquid Pycnometer 23.9760 1.6605 75.0 2.5 57.8874 6.3146
10 Liquid RI 4.8889 0.5748 55.0 2.5 38.0896 4.0122
11 Liquid RI 1.7778 0.5691 35.0 2.5 9.3645 2.5398
12 Liquid RI 5.5556 0.5752 60.0 2.5 -6.9388 -1.5218
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The Trouble
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The IPA separation
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The ETOH separation
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The model

• The IPA Aspen model
• -4.7 at the top
• 8.4 at the bottom
• The three important stages 7, 9, and 10
  Murphree-vapor efficiencies were 91.918.7,
  57.96.3, 38.44.0
• Overall column efficiency 8.3
• Stage efficiency did not matter

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The Aspen model for ETOH

• Max flow rate 2.13 GPM
• Steam flow rate 1.67 kg/min
• Condenser heat duty -1739 kJ/min
• Feed composition 2.5 wt ETOH
• Distillate composition 40 wt ETOH
• ETOH recovery 99.4

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Recomendations

• Replace the automatic control valve for the steam
  flow to the reboiler.
• Replace the leaky manual steam valve.
• Refine the ETOH model with steady state data.

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Special thanks to team-J

• Jaron Stanley Team Leader
• James Gardner Operator
• Jesse Reeves Team player

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References

• Seader, J. D., Henley, Ernest J., Separation
  Process Principles, John Wiley Sons, Inc. pp.
  44, 301, 358-397 (1998).
• Distillation Column Manual, unpublished printed
  notes, Univ. of Utah, Salt Lake City, Utah 1997.

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Questions

• ?