chen 4460 – process synthesis, simulation and optimization dr. mario richard eden department of...
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CHEN 4460 – Process Synthesis, Simulation and Optimization
Dr. Mario Richard EdenDepartment of Chemical Engineering
Auburn University
Lab Lecture No. 4 – Selection of Property Models
October 2, 2012
Contains Material Developed by Dr. Daniel R. Lewin, Technion, Israel
Choosing Property Models
Importance of Selection
• Correct predictions of physical properties of the mixture as function of temperature and pressure.
• Each method is suitable only for particular types of components and limited to certain operating conditions.
• Choosing the wrong method may lead to incorrect simulation results.
• Particularly important for reliable computations associated with separation operations (distillation, LL extraction, etc.).
Principal Selection Steps
Choosing the most suitable model/thermo method.
Comparing the obtained predictions with data from the literature.
Adding estimates for components not available in the chosen thermo package. Can they be neglected?
Generation of lab data if necessary to check the thermo model.
Sources of Information
• Publications and professional literature that deal with the process in question or with the components that participate in the process.
• Simulator reference manual (HELP).
• DATABANKS
• Rules of thumb.
Types of Models
EOS Models Activity Coefficient ModelsLimited ability to represent non-ideal liquids Can represent highly non-ideal liquids
Consistent in critical region Inconsistent in critical region
Can represent both vapor and liquid phases Can represent liquid phase only. Gas phase must still be described by an EOS model
Parameters extrapolate well with temperature Binary parameters are highly dependent on temperature
Do you have any POLARcomponents in your system?
NO YES
YESUse EOS ModelAre the operating conditions
near the CRITICAL region of themixture?
Do you have LIGHT gases orSUPERCRITICAL components
in your system?
NO
NO YES
Use Activity CoefficientModel
Use Activity CoefficientModel with Henry’s law
Recommendations
• Eric Carlson, “Don’t gamble with physical properties for simulations,” Chem. Eng. Prog. October 1996, 35-46.
• Prof J.D. (Bob) Seader, University of Utah
• Aspentech Recommendations
Eric Carlson
E?
R?
P?
Polar
Real
Electrolyte
Pseudo & Real
Vacuum
Non-electrolyte
Braun K-10 or ideal
Chao-Seader,Grayson-Streed or Braun K-10
Electrolyte NRTLOr Pizer
See Figure 2
Polarity
R?Real or pseudocomponents
P? Pressure
E? Electrolytes
All Non-polar
Figure 1
Peng-Robinson,Redlich-Kwong-SoaveLee-Kesler-Plocker
Eric Carlson
P?
ij?
ij ?
LL?
(See alsoFigure 3)
P < 10 bar
(See alsoFigure 3)
P < 10 bar
P > 10 barP > 10 bar
PSRKPR or SRK with MHV2
Schwartentruber-RenonPR or SRK with WSPR or SRK with MHV2
UNI FAC and itsextensions
UNI FAC LLE
PolarNon-electrolytesPolarNon-electrolytes
NoNo
YesYes
YesYes
LL?NoNo
NoNo
YesYes
YesYes
NoNo
WI LSON, NRTL,UNI QUAC and their variances
NRTL, UNI QUACand their variances
LL? Liquid/ Liquid
P? Pressure
ij ? I nteraction ParametersAvailable
Figure 2
VAP?
DP?YesYes
NoNoWilson, NRTL,UNI QUAC, or UNI FAC* with ideal Gas or RK EOS
Wilson NRTLUNI QUACUNI FAC
Wilson NRTLUNI QUACUNI FAC
HexamersHexamers
DimersDimersWilson, NRTL, UNI QUAC,UNI FAC with Hayden O’Connellor Northnagel EOS
Wilson, NRTL, UNI QUAC,or UNI FAC with special EOS f or Hexamers
VAP? Vapor Phase Association
Degrees of PolymerizatiomDP?UNI FAC* and its Extensions
Eric Carlson
Figure 3
Bob Seader
LG?
E?
PC?
HC?
YesYes
YesYes
NoNo
YesYes
See Figure 5
Special: e.g., Sour Water (NH3, CO2, H2S, H2O)Aqueous amine solution with CO2 and H2S
PC?
NoNo
Modifi ed NRTL
NoNo
NoNo
PSRKYesYes
NoNoSee Figure 5
See Figure 6
HC? Hydrocarbons
LG? Light gases
PC? Organic Polar Compound
E? Electrolyte
YesYes
Bob Seader
Figure 4
Bob Seader
Figure 5
T?
P?
BP?
Narrow orwideNarrow orwide
PR
LKP
Cryogenic Cryogenic
Non- Cryogenic Non- Cryogenic
Critical Critical
Non-CriticalNon-Critical
SRK, PR
PR, BWRS
Very wideVery wide
HC and/ or LGHC and/ or LG
P? Pressure region
T? Temperature region
BP? Boiling point range of compound
Bob Seader
Figure 6
PPS?
BI P?
AvailableAvailable
UNI FAC
Yes Yes
NoNoWilson
NRTL, UNI QUAC
Not AvailableNot Available
PC with HCPC with HC
PPS? Possible PhaseSplitting
BI P? Binary I nteractionParameters
Aspentech
Example: 1-Propanol/Water
• Find the best thermodynamic package for 1-Propanol , H2O mixture.
• Eric Carlson, “Don’t gamble with physical properties for simulations,” Chem. Eng. Prog. October 1996, 35-46.
• Prof J.D. (Bob) Seader, University of Utah
Carlson: 1-Propanol/Water
E?Polar
Non-electrolyteSee Figure 2
Polarity
R?Real or pseudocomponents
P? Pressure
E? Electrolytes
Figure 1
Carlson: 1-Propanol/Water
P?
ij?
LL?
(See alsoFigure 3)
P < 10 bar
UNIFAC and its extensions
PolarNon-electrolytes
Yes
LL?No
No
No
WILSON, NRTL,UNIQUAC and their variances
LL? Liquid/Liquid
P? Pressure
ij? Interaction Parameters Available
Figure 2
Seader: 1-Propanol/Water
LG?
HC?
Yes
No PC?
See Figure 6
HC? Hydrocarbons
LG? Light gases
PC? Organic Polar Compound
E? Electrolyte
Yes
Figure 4
Seader: 1-Propanol/Water
Figure 6
PPS?
BIP?
Available
UNIFAC
Yes NRTL, UNIQUAC
Not Available
PC with HC
PPS?Possible PhaseSplitting
BIP? Binary Interaction Parameters
Solution: 1-Propanol/Water
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 182
84
86
88
90
92
94
96
98
100
1-Propanol mol. frac.
T [o
C]
TXY diagram f or 1-Propanol, H2O
Perry NRTL PRSV UNIQUAC Van-Laar (Built-inVan-Laar(Perry)
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