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Choosing Property Models. CHEN 4460 – Process Synthesis, Simulation and Optimization Dr. Mario Richard Eden Department of Chemical Engineering Auburn University Lab Lecture No. 4 – Selection of Property Models October 2, 2012
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Choosing Property Models CHEN 4460 – Process Synthesis, Simulation and Optimization Dr. Mario Richard EdenDepartment of Chemical EngineeringAuburn University Lab Lecture No. 4 – Selection of Property Models October 2, 2012 Contains Material Developed by Dr. Daniel R. Lewin, Technion, Israel
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.
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
Non-electrolyte Polar Electrolyte Real All Non-polar Pseudo & Real Vacuum Eric Carlson Figure 1 See Figure 2 E? Electrolyte NRTL Or Pizer Peng-Robinson, Redlich-Kwong-Soave Lee-Kesler-Plocker R? Chao-Seader, Grayson-Streed or Braun K-10 Polarity Real or pseudocomponents P? R? P? Pressure Braun K-10 or ideal E? Electrolytes
Eric Carlson Figure 2
Eric Carlson Figure 3
Bob Seader Figure 4
Bob Seader Figure 5
Bob Seader Figure 6
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
Non-electrolyte Polar Carlson: 1-Propanol/Water Figure 1 See Figure 2 E? Polarity Real or pseudocomponents R? P? Pressure E? Electrolytes
Yes P < 10 bar No (See also Figure 3) No Polar Non-electrolytes No Carlson: 1-Propanol/Water Figure 2 LL? WILSON, NRTL, UNIQUAC and their variances ij? P? LL? UNIFAC and its extensions LL? Liquid/Liquid P? Pressure ij? Interaction Parameters Available
Yes Yes No Seader: 1-Propanol/Water Figure 4 HC? Hydrocarbons LG? Light gases E? Electrolyte LG? PC? Organic Polar Compound See Figure 6 PC? HC?
Yes Available PC with HC Not Available Seader: 1-Propanol/Water Figure 6 NRTL, UNIQUAC PPS? BIP? BIP? Binary Interaction Parameters UNIFAC PPS? Possible Phase Splitting