Properties of Material Streams: The Evaluation Sequence

The purpose of this portion of TDE is calculation of properties (with uncertainty analysis) for material streams (one or more components) that occur in process design.

Characteristics of properties of a material stream evaluated in TDE

• Properties of material streams are evaluated based on the properties of the stream components and the combination of property models for all binary sub-systems.
• To calculate properties, an Activity Coefficient Model must be applied successfully to all of the binary sub-systems.

Calculation Types: Property calculations can be made for the following conditions...

1. selected (fixed) temperatures and pressures
2. at the bubble point
3. at the dew point

Evaluated properties at selected (fixed) temperature and pressure

K values, Dimensionless: The ratio of the mole fraction in the gas phase to that in the liquid calculated for each component (K1, K2, etc., where the numbers represent the component numbers given in the Navigation Tree).

Gas composition, Dimensionless: The composition is expressed in mole fraction Y for each component.
Liquid composition, Dimensionless: The composition is expressed in mole fraction X for each component.
Vapor fraction, Dimensionless: The mole fraction of the material stream in the vapor phase.

Evaluated properties at the bubble point

Phase boundary pressure, kPa
Density, kg/m3: The density of the liquid phase at the bubble point pressure
Excess Enthalpy, kJ/mol
K values, Dimensionless: Defined above.
Gas composition, Dimensionless: Defined above.

Evaluated properties at the dew point

Phase boundary pressure, kPa
K values, Dimensionless: Defined above.
Liquid composition, Dimensionless: Defined above.

• Properties evaluated by TDE for a material stream are not stored in the Navigation Tree; however, the compositions (tree node = Material Compositions) and calculation conditions (tree node = Material Property Calculations) are stored, allowing simple re-calculation.