Transcript Lecture 17

Unit Operations
Lecture 16_17
22 – 31 Oct 2012
1
Overview
•Review rigorous methods / RADFRAC
• Multicomponent systems:
o Residue curves
o DSTWU / RADFRAC
o Rules of thumb
• Complex (Enhanced) distillation
• Column internals
• Batch distillation
2
Multicomponent
Rigorous Methods
Rigorous Methods: solution of
stage by stage material
balances, energy balances, and
thermodynamic equilibrium
equations.
3
AspenPlus: RADFRAC
Rigorous two- or three-phase fractionation for single columns.
Models absorbers, strippers, reactive distillation, and so forth.
• RadFrac is a rigorous model for simulating all types of multistage vapor liquid
fractionation operations. In addition to ordinary distillation, it can simulate:
o absorption, reboiled absorption, stripping, reboiled stripping, extractive and
azeotropic distillation
4
Rigorous
Model
5
AspenPlus: RADFRAC
Rigorous two- or three-phase fractionation for single columns.
Models absorbers, strippers, reactive distillation, and so forth.
• RadFrac is a rigorous model for simulating all types of multistage vapor liquid
fractionation operations. In addition to ordinary distillation, it can simulate:
o absorption, reboiled absorption, stripping, reboiled stripping, extractive and
azeotropic distillation
• RadFrac is suitable for:
o three phase systems, narrow boiling and wide boiling systems, systems
exhibiting strong liquid phase nonideality
• RadFrac can detect and handle a free water phase or other second liquid phase
anywhere in the column. You can decant free water from the condenser.
• RadFrac can handle solids on every stage.
• RadFrac can model columns where chemical reactions are occurring. Reactions can
have fixed conversions, or they can be:
o equilibrium, rate controlled, electrolytic
• RadFrac can model columns where two liquid phases exist and different chemical
reactions occur in the two liquid phases. RadFrac can also model salt precipitation.
• RadFrac can operate in rating mode or design mode.
• With Aspen Rate-Based Distillation feature, RadFrac can perform rate-based
distillation calculations (packed tower configurations).
6
Rating Mode
7
8
9
Design Mode
10
Rigorous
Model
11
Multicomponent Methods
AspenPlus (methanol, ethanol, 1-propanol):
Component
MeOH
EtOH
1-Propanol
P*i
(64.5 oC)
1.013 bar
0.5709
0.2534
Keys
AspenPlus Txy
12
“Residue” From Batch Distillation
Seader & Henley (2006)
13
Residue Curve Map
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Residue Curve Map
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Residue Curve Map
16
DSTWU
Zi = 1/3
MeOH recovery (dist.) = 99.9%
R = 1.2 * Rmin
EtOH recovery (dist.) = 0.1%
17
RADFRAC
Zi = 1/3
F = 100 kmol/h
R = 5.2
N = 63
NF = 31
D = 33 kmol/h
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Residue Curve Map
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Plot Wizard
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NF = 21
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Set up Scheme 2 (1st column only)
• Run DSTWU
• Run RADFRAC
• Check performance
22
Questions?
23