Configure the equilibrium options for a Fluid Type that uses the Electrolyte NRTL 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 Electrolyte Non-Random Two-Liquid (NRTL) method includes additional equilibrium options compared to the other liquid activity coefficient (LACT) methods. Therefore, we document the equilibrium options for the Electrolyte NRTL method separately from the other LACT methods available in AVEVA Process Simulation.

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

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

7. (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.

8. (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.

9. (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.

10. Expand the Models section.

11. (Optional) In the Reaction box, enter the name of the Electrolyte NRTL reaction submodel that you want to use for your electrolyte dissociations.

    You can use one of the following default Electrolyte NRTL reaction submodels from the Fluids Library or a custom Electrolyte NRTL reaction submodel. When you create a custom Electrolyte NRTL reaction submodel, we recommend that you copy one of the default Electrolyte NRTL reaction submodels and modify it with your custom dissociation reaction data.

    • Fluids.RXHCl_eNRTL: Provides reaction data for the dissociation of HCl in water.

    • Fluids.RXHNO3_eNRTL: Provides reaction data for the dissociation of HNO3 in water.