ProMax includes a number of default Property Packages applicable to gas processing, refining, electrolytic, and molecular chemical systems.
EOS (Equation of State)
- EOS models calculate both liquid and vapor properties and are generally used to model systems such as LNG and cryogenic processes, mixed refrigerants, air separation, low temperature oil absorption processes, light naphtha processing, and hydrogen systems.
- EOS models can calculate pure, mixture, and infinite dilution properties.
- Available EOS models are:
- Peng-Robinson Polar
- SRK Polar
- Peng-Robinson and SRK can be used to model other processes such as dehydration and crude fractionation. Both of these models also support hydrate, water freezing point, and CO2 freeze out predictions.
Pure Component Models
ProMax includes two Pure Component models:
NBS Steam Tables calculates thermodynamic, physical, and transport properties for water. This package could be used to model steam turbines, condensers, steam cycle, etc. to obtain duties.
Heat Transfer Fluid uses correlations to calculate thermodynamic, physical, and transport properties for common heat transfer fluids such as DowTherm, MultiTherm, Therminol, etc.
Gibbs Excess/Activity Coefficient Models
- Unlike EOS models, Gibbs Excess/Activity Coefficient models calculate infinite dilution and mixture properties for the liquid phase only, and cannot calculate pure properties or vapor phase properties.
- When a Gibbs Excess/Activity Coefficient model is selected, liquid properties are calculated using the specified model, and vapor phase properties are calculated using Ideal Gas (IG), Peng Robinson (PR), or Soave-Redlich-Kwong (SRK).
- For low pressure (70 psia or less), Ideal Gas should be suitable for predicting vapor phase properties.
- For higher pressures, SRK or PR should be used to calculate vapor phase properties because they account for vapor phase imperfections at higher pressures.
- Although the Electrolytic and Molecular Gibbs Excess/Activity Coefficient models are both considered Gibbs Excess models, they are discussed separately below.
Molecular Gibbs Excess/Activity Coefficient Models
- Molecular Gibbs Excess/Activity Coefficient models calculate only liquid properties for mixtures, and are not intended to calculate pure properties.
- These models are applicable to binary and multicomponent systems and are intended to be used in chemical industry type applications.
- Gas Processing applications should instead use an EOS model for general properties and an Electrolytic Gibbs Excess/Activity Coefficient model for amine treating of hydrocarbons.
- Available Molecular Gibbs Excess/Activity Coefficient models are:
- Chien Null
- Regular Solution
- TK Wilson
- UNIFAC LLE
- UNIFAC VLE
- Van Laar
Electrolytic Gibbs Excess/Activity Coefficient Models
- Gibbs Excess/Activity Coefficient models calculate only liquid properties for mixtures, and are not intended to calculate pure properties.
- Electrolytic models are applicable for systems in which dissociation of compounds is important (e.g. amine sweetening applications and systems containing ammonia and an acid gas such as H2S or CO2).
- Systems containing glycols should not be modeled using an electrolytic package. Instead, an Equation of State model such as Peng-Robinson or SRK should be used.
- There are three Electrolytic Models:
- Electrolytic ELR
- Electrolytic NRTL
- Electrolytic Kent-Eisenberg
Defining a Custom Package
- The Predefined Property Packages contain default methods for calculating physical properties and should normally be used for all physical property calculations. However, the calculation method for one or more physical properties can be changed, thereby "customizing" the Predefined Package.
- Use Custom Package is an advanced feature requiring thorough knowledge of the property evaluation methods and is generally used to make minor changes to a Predefined Property Package.