1. How to chose the best property prediction method for simulation ?
Exercise 2
How to chose the best property prediction method for simulation ?
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Design & Analysis II

2. Importance of Selecting the Appropriate Prediction Method
Correct predictions of the physical properties of the mixture as a 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.).
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Design & Analysis II

3. Principle Steps in Selecting the Appropriate Thermodynamics Package
Choosing the most suitable model/thermo method.
Comparing the obtained predictions with data from the literature.
Adding estimates for components that not available in the chosen thermo package. Can they be neglected?
Generation of lab data if necessary to check the thermo model.
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Design & Analysis II

4. 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.
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Design & Analysis II

5. Issues in Selection of the Appropriate Thermodynamics Package
Nature of mixture (e.g., hydrocarbon, polar, electrolyte, etc.)
Pressure and temperature range
Availability of data.
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Design & Analysis II

6. Recommendations for the Selection of the Appropriate Thermodynamics Package
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
Hyprotech Recommendations
7/24/2019
Design & Analysis II

7. Eric Carlson’s Recommendations
Figure 1
Non-electrolyte
See Figure 2 E?
Polar
Electrolyte
Electrolyte NRTL
Or Pizer
Real
Peng-Robinson,
Redlich-Kwong-Soave,
Lee-Kesler-Plocker
All
Non-polar R?
Chao-Seader,
Grayson-Streed or
Braun K-10
Polarity
Pseudo & Real
Real or
pseudocomponents P? R? P?
Pressure
Vacuum
Braun K-10 or ideal E?
Electrolytes
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Design & Analysis II

8. Figure 2 LL? ij? P? LL? ij? Yes NRTL, UNIQUAC and their variances Yes
WILSON, NRTL,
UNIQUAC and
their variances
ij?
(See also
Figure 3)
P < 10 bar No
Yes No
UNIFAC LLE P?
LL?
Polar
Non-electrolytes
P > 10 bar No
UNIFAC and its
extensions
Schwartentruber-Renon
PR or SRK with WS
PR or SRK with MHV2
LL?
Yes
Liquid/Liquid
ij? P?
Pressure No
PSRK
PR or SRK with MHV2
ij?
Interaction Parameters
Available
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Design & Analysis II

9. Figure 3 DP? Wilson, NRTL, UNIQUAC, or UNIFAC with special EOS
for Hexamers
Figure 3
Hexamers
DP?
Yes
Wilson, NRTL, UNIQUAC,
UNIFAC with Hayden O’Connell
or Northnagel EOS
Dimers
VAP?
Wilson
NRTL
UNIQUAC
UNIFAC
Wilson, NRTL,
UNIQUAC, or UNIFAC*
with ideal Gas or RK EOS No
VAP?
Vapor Phase Association
UNIFAC* and its Extensions
DP?
Degrees of Polymerizatiom
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Design & Analysis II

10. Bob Seader’s Recommendations
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Design & Analysis II

11. Bob Seader’s Recommendations
Yes
Figure 4
PSRK
HC?
Hydrocarbons
PC?
Yes
LG?
Light gases No E?
Electrolyte
See Figure 5
Yes
LG?
Yes
PC?
Organic Polar
Compound
See Figure 6 No
PC?
HC? No
See Figure 5 No
Yes
Modified NRTL E? No
Special: e.g., Sour Water (NH3, CO2, H2S, H2O)
Aqueous amine solution with CO2 and H2S
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Design & Analysis II

12. Figure 5 P? T? BP? Critical PR Cryogenic Narrow or wide Non-Critical
PR, BWRS T?
HC and/ or LG
Non- Cryogenic
BP?
SRK, PR
Very wide
BP?
Boiling point range
of compound
LKP T?
Temperature region P?
Pressure region
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Design & Analysis II

13. Figure 6 PPS? BIP? Yes NRTL, UNIQUAC Available No PC with HC Wilson
Not Available
BIP?
Binary Interaction
Parameters
UNIFAC
PPS?
Possible Phase
Splitting
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Design & Analysis II

14. Hyprotech Recommendations
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Design & Analysis II

15. Example
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
7/24/2019
Design & Analysis II

16. Eric Carlson’s Recommendations for 1-Propanol ,H2O mixture
Figure 1
Non-electrolyte
See Figure 2 E?
Polar
Polarity
Real or
pseudocomponents R? P?
Pressure E?
Electrolytes
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Design & Analysis II

17. Figure 2 LL? ij? P? LL? Yes WILSON, NRTL, UNIQUAC and their variances
(See also
Figure 3)
P < 10 bar No No P?
LL?
Polar
Non-electrolytes No
UNIFAC and its
extensions
LL?
Liquid/Liquid P?
Pressure
ij?
Interaction Parameters
Available
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Design & Analysis II

18. Bob Seader’s Recommendations for 1-Propanol ,H2O mixture
Figure 4
HC?
Hydrocarbons
LG?
Light gases E?
Electrolyte
Yes
LG?
Yes
PC?
Organic Polar
Compound
See Figure 6 No
PC?
HC?
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Design & Analysis II

19. Figure 6 PPS? BIP? Yes NRTL, UNIQUAC Available PC with HC
Not Available
BIP?
Binary Interaction
Parameters
UNIFAC
PPS?
Possible Phase
Splitting
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Design & Analysis II

20. 1-Propanol, H2O
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Design & Analysis II

21. TXY macro for HYSYS
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Design & Analysis II