Configure the equilibrium options for a Fluid Type that uses the NRTL, UNIQUAC, or Wilson method

The Equilibrium Options section in the Fluid Editor provides a set of advanced equilibrium options that allow you to adjust your equilibrium calculations to suit your needs. The equilibrium options that are available depend on the type of thermodynamic method that you use as the System method for your Fluid Type.

The following liquid activity coefficient (LACT) methods have similar equilibrium options:

• Non-Random Two-Liquid (NRTL)

• Universal Quasi-Chemical (UNIQUAC)

• Wilson

Configure the equilibrium options

1. Open the Fluid Type in the Fluid Editor if the Fluid Type is not already open.

2. Expand the Equilibrium Options section if it is not already visible.

   

3. If the option selected in the Phases list in the System section includes a vapor phase, in the Vapor Equilibrium list, select the thermodynamic method that you want AVEVA Process Simulation to use when it calculates the vapor phase equilibrium properties.

4. (Optional) Select the Use Azeotrope Fill checkbox to estimate missing vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE) interaction parameters by regressing azeotropic data from a data bank to provide binary interaction data.

   The Azeotrope Data Banks area appears.

   

   The software provides estimates for the interaction parameters only when azeotropic data is available for both components in the binary pair. If the data banks that your Fluid Type uses do not include azeotropic data for the components in question, selecting the Use Azeotrope Fill checkbox has no effect on the Fluid Type.

5. If you want to use custom data banks of azeotropic data, in the Azeotrope Data Banks area, select Expand and add the custom data banks that you want to use.

   See Data banks for a Fluid Type for more information.

   The Azeotrope Data Banks area is available only when the Use Azeotrope Fill checkbox is selected.

6. (Optional) Select the Use Dortmund UNIFAC Fill checkbox to calculate missing binary interaction parameters by using group interaction data from a Dortmund UNIFAC data bank.

   The Fill Method Group Information Banks area appears.

   

   The Use Dortmund UNIFAC Fill checkbox is currently available only when you select Non-Random Two-Liquid (NRTL) or Wilson in the System list.

   The software provides estimates for the binary interaction parameters only when group contribution data is available for both components in the binary pair. If the data banks that your Fluid Type uses do not include group contribution data for the components in question, selecting the Use Dortmund UNIFAC Fill checkbox has no effect on the Fluid Type.

   If you select both the Use Azeotrope Fill and Use Dortmund UNIFAC Fill checkboxes, the software fills the missing interaction parameters first from the azeotropic data and then from the Dortmund UNIFAC group contribution data if there is no azeotropic data available.

   See UNIFAC — UNIQUAC Functional-group Activity Coefficient method for more information on how the binary interaction parameters are calculated.

7. If you want to use custom data banks of Dortmund UNIFAC group contribution data, in the Fill Method Group Information Banks area, select Expand and add the custom data banks that you want to use.

   See Data banks for a Fluid Type for more information.

   The Fill Method Group Information Banks area is available only when the Use Dortmund UNIFAC Fill checkbox is selected.

8. Configure the Henry's Law options as you desire.

   See Configure the Henry's Law options for a Fluid Type for more information.

9. (Optional) Select the Use Poynting Correction checkbox to include the Poynting correction factor in the equilibrium calculations.

   The Poynting correction always uses the pure component volume data calculated from the temperature-dependent property correlations for liquid density, as defined in both the PURECOMP data bank from the thermodynamic library that the Fluid Type uses and the local thermodynamic data overrides specified on the Temp Dep tab in the Component Data section of the Fluid Editor. See Effects of specifying thermodynamic method overrides for more information.

10. (Optional) Select the Include Fugacity Coefficient Variables in Fluid State checkbox to add variables for the fugacity coefficients to the Fluid State model.

    You can now view the calculated values for the fugacity coefficients or use them in other areas of the simulation.

11. (Optional) If the option selected in the Phases list in the System section includes a liquid phase, select the Include Activity Coefficient Variables in Fluid State checkbox to add variables for the activity coefficients to the Fluid State model.

    You can now view the calculated values for the activity coefficients or use them in other areas of the simulation.