Exercise MTBE column

1
Exercise - MTBE column

• The MTBE column is an industrial distillation
  column separating MTBE from butanes, butenes and
  methanol.
• The column is 1.7 meters in diameter.
• It has 28 valve plates.
• The plates above the feed plate (plate 14) are
  one-pass plates.
• Plates below the feed plate are two-pass type.
• The feed contains mainly MTBE, C3/C4 hydrocarbons
  and methanol.
• The distillate contains mainly iso-butane,
  1-butene and methanol.
• The bottom product is mainly MTBE.
• The operating pressure is about 700 kPa (abs).

2
Exercise - MTBE column (Continued)

• Feed composition kg/h w-
• Water 19 0.05
• n-hexane 91 0.22
• i-butene 374 0.89
• methanol 560 1.34
• 1-butene 6459 15.4
• i-butane 10471 25.0
• n-butane 3889 9.28
• t-2-butane 4602 11.0
• c-2-butane 3279 7.82
• MTBE 12177 29.0
• Total 41921 100

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Exercise - MTBE column (Continued)

• Column specifications
• Distillation trays 28 pieces
• Feed tray is no. 16 (including reboiler)
• Bottom product 12 451 kg/h
• Distillate 29472 kg/h
• Reflux ratio 0.439, temperature 303 K
• Pressure 696 kPa
• Pressure drop/tray 0.64 kPa/tray
• Condenser pressure drop 5.0 kPa
• Feed pressure 750 kPa, temperature 331 K
• TUNITS 3600
• 1. Specify the column and simulate with ideal
  trays.

4
Exercise - MTBE column (Continued)

• 2. Input tray details for two sections
• 3. Calculate point efficiencies of multicomponent
  system
• 4. Study point efficiencies by using Excel

5
Exercise - MTBE column (Continued)

• Trays 29 - 16
• Downcomer area 0.250 m2
• Total hole area 0.348 m2
• Active area 2.02 m2
• Downcomer clearance 4.5 cm
• Hole diameter 3.88 cm
• Tray spacing 60 cm
• Weir height 5.1 cm
• Flow path length 1.350 m
• Length of weir 1.119 m
• Thickness of plate 0.20 cm
• Note
• Give same values for LWEIR and WFLOW

• Trays 15 - 2
• Downcomer area 0.587 m2
• Total hole area 0.294 m2
• Active area 1.851 m2
• Downcomer clearance 3.5 cm
• Hole diameter 3.88 cm
• Tray spacing 70 cm
• Weir height 3.8 cm
• Flow path length 0.525 m
• Length of weir 1.4235 m
• Thickness of plate 0.20 cm
• Note
• Give same values for LWEIR and WLOW

6
Exercise - MTBE column (Continued)

• For both sections
• Efficiency calculation methods for point
  efficiencies
• NTU-method
• Method of Chan and Fair
• MTHEMV 14
• Mass transfer model
• Bootstrap matrices are included into model (most
  rigorous model)
• MTHE0G 2
• For point efficiencies
• LIQFLO 1
• Add
• MTHCAL 1 to namelist DISTIL
• MTHCON 1 to namelist DISTIL
• MTHEQU 0 to both namelist SECT

7
Exercise - MTBE column (Continued)

• 5. Input tray details for two sections
• 6. Calculate Murphree tray efficiencies of
  multicomponent system
• 7. Study Murphree tray efficiencies by using
  Excel
• 8. Compare point and tray efficiencies

8
Exercise - MTBE column (Continued)

• Change
• Liquid mixing model
• Rigorous partial mixing model
• Degree of mixing
• Welch et. al. eddy diffusivity calculation
• Simulate column