“Chemical Engineering Equilibrium Separations”
Lectures 12 & 13
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12 Oct 2012
Overview
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• AspenPlus:o Shortcut methods: DSTWUo Rigorous method: RADFRAC
• Efficiencies• Introduction to multicomponent distillation
AspenPlus: DSTWU
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Tray Operation
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a) Sprayb) Froth *c) Emulsiond) Bubblee) Cellular foam
Types of Trays
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a) Sieveb) Valvec) Bubble cap
Typical Flow Pattern
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Operation
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Typically columns operated at 50% - 85% of flooding.
Seader et.al., 2012Figure 6.21 Limits of stable operation in a trayed tower. [Reproduced by permission from H.Z. Kister, Distillation Design, McGraw-Hill, New York (1992).]
Operation
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Video:FRI (Fractionation Research, Inc.) non-profit research consortium“Design and Performance of Fractionating Devices”
http://www.fri.org/
Operation
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Typically columns operated at 50% - 85% of flooding.
Seader et.al., 2012Figure 6.21 Limits of stable operation in a trayed tower. [Reproduced by permission from H.Z. Kister, Distillation Design, McGraw-Hill, New York (1992).]
Efficiencies
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Assumed equilibrium stages, but may not reach equilibrium on a stage;
why?
Flooding!
Efficiencies
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Overall column efficiency:actual
equilO N
NE
Murphree efficiency:..
.* equilatchangeconcvapor
changeconcvaporactual
yy
yyE
inout
inoutMV
)417(1
*1
eqnyy
yyE
nn
nnMV
OGNMV eE 1
Efficiencies
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Efficiencies
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Seader & Henley, 2006
Efficiencies
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MVE
P.C. Wankat, 2nd., 2007
Overview
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• Questions on homework??• McCabe-Thiele graphical technique (binary systems)
• Condensers• Reboilers
• Binary Shortcut Methods• AspenPlus:o Shortcut methods: DSTWUo Rigorous method: RADFRAC
• Efficiencies• Introduction to multicomponent distillation (chapter 9)
Questions?
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