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Chemical Process Simulation - ChemCAD Thermodynamic Thermodynamic • Type of solutions/Classification of solution • Recommendations for selection of thermodynamics model - Equations of state (Hydrocarbons) - Activity coefficients model (Chemicals) - Electrolyte model (Electrolyte) - Special models • Workshop Type of Solutions IDEAL Uniform-sized molecules are randomly located. REGULAR Different sized molecules are randomly located. NON-IDEAL (POLAR) Molecules are segregated by type in very strong clusters. ELECTROLYTES Molecules may ionize in solution. H H Cl- H+ H H Cl- H H H+ H H Thermodynamic Model Selection ◎ IDEAL Solution - Vapor Pressure - Equation of State ◎ REGULAR Solution - Equation of State ◎ POLAR Solution - Activity Coefficient Model ◎ ELECTROLYTES Solution - Electrolytes Model ◎ POLYMER Solution - Polymer Model K-Value Options ◎ IDEAL Solution — Pure component Vapor Pressure Pure component ◎ REGULAR Solution — Hydrocarbons ---- Equation of State Soave-Redlich-Kwong High-moderate P& T’s Hydrocarbon Chao-Seader High-moderate P& T’s Hydrocarbon Peng-Robinson High-moderate P& T’s Hydrocarbon API Soave High-moderate P& T’s Hydrocarbon Grayson Streed Moderate P& T’s Hydrocarbon Maxwell-Bonnell K-Charts Low Pressure, Heavy Hydrocarbon K-Value Options ◎ NON-IDEAL (POLAR) Solution — Chemicals UNIFAC UNIQUAC NRTL Wilson T. K. Wilson Hiranuma(HRNM) Wilson Salt Margules Van Laar Regular Solution T=275-475K, P=0-4 atm VLE,LLE,Predictive Highly non-ideal VLE,LLE Highly non-ideal, VLE,LLE Highly non-ideal, VLE Highly non-ideal, VLE,LLE Highly non-ideal, VLE,LLE Non-ideal solutions with salts dissolved Highly non-ideal, VLE,LLE (4 suffix) Moderately non-ideal Moderately non-ideal (Predictive) Modified SRK (4 parameters) Predictive SRK Polar compounds in regular solutions Polar components in non-ideal solutions. better than UNIFAC at high pressures EDC, SAFT K-Value Options ◎ ELECTROLYTES Solution Amines (MEA, DEA) Gas sweetening Sour Water Acid Gases and NH3 dissolved in H2O PPAQ General, but electrolyte system is most common application (HCl, NH3, HNO3) Ideal Pitzer NRTL for electrolyte 1982 NRTL for electrolyte 1986 K-Value Options ◎ SPECIAL TECHNIQUES Henry's Law TSRK TEG FLOR UPLM ACTX Polynomials K Tables User-Added Subroutine Gases dissolved in Water Methanol system; particularly with light gases Dehydration of hydrocarbon streams using tri-ethylene-glycol Flory-Huggins method for polymers UNIFAC for polymers User specified activity coefficients User K's User K's User K's K-Value Options Hydrocarbons System K-model H-model Ordinary SRK SRK Cryogenics PR Crude CS, GS PR LK ESSO LK SRK SRK Vacuum Crude Power Combustion Acids, Bases, Electrolytes Chemicals Electrolytes Models SRK, HTSL Activity Coeff. Latent Heat Activity Coefficient Models Van Laar Margules UNIFAC NRTL UNIQUAC Wilson VLE Yes Yes Yes Yes Yes Yes LLE No Yes Yes Yes Yes No Accuracy Good Good Good Very Good Very Good Best Simplicity Simple Simple Complex Complex Complex Complex Calculation Fast Fast Slow Slow Slow Slow BIPs - - - Need Need Need H-Value Options K-value H-value K-value H-value SRK SRK VANL LATE PR PR MARG LATE BWRS BWRS REGU SRK APIS SRK AMMI AMMI Grayson-Streed Lee-Kesler SOUR SRK MSRK SRK TEG SRK PSRK LATE TSRK SRK ESSO Lee-Kesler PPAQ SRK or LATE VAP LATENT FLOR LATENT NRTL LATENT UPLM LATENT UNIF LATENT T.K. Wilson LATENT UNIQ LATENT Hiranuma(HRNM) LATENT WILS LATENT ACTX LATENT Thermodynamics Wizard Define components, and set max. amd min. pressures, and temperatures, respectively Bip data threshold : For activity coeff. Model reference Start P< 1 atm Check Class No H=Latent Chemicals K=VAP K=GS K=ESSO H=LEEK H=LEEK NC=1 No No Crude Oil H=SRK No Amine K=Amine H-Amine No Sour No Polymer No Electrolytes No Chemical P<200psi No Chemical No T<100F No K=Sour K=LPLM K=PPAQ, E-NRTL Check BIPs K=PSRK, ESD, SAFT K=PR K=SRK H=Sour H=Latent H=SRK K=NRTL,Wilson, UNIQ, UNIF H=Latent H=PR H=SRK HTSL H=Latent K Model Selection and Option H Model Selection and Option Workshop : Phase Equil. with Fugacity Correction System: Methanol/Water, Fugacity correction (Y/N) Results: Low pressure(1 atm) High pressure(30atm) Comment: Fugacity correction may be important at relatively high pressure. 1 atm without fugacity correction 1 atm with fugacity correction 30 atm without fugacity correction 30 atm with fugacity correction Workshop : Vapor Phase Association System: Acetic Acid/Water, Vapor Phase Association(Y/N) Results: With Vapor Phase Association and without Vapor Phase Association Conclusion: Organic acids in gas phase (forming dimer) needs vapor phase association Water and Acetic Acid No Vapor Phase Association With Vapor Phase Association