VLLE Calculations

VLLE calculations represent equilibrium between one vapor and two liquid phases. PRO/II contains a number of thermodynamic methods that can predict the K-values and distribution coefficients for these calculations.

Both Liquid Activity and Advanced Equations of State methods may be used to perform three-phase calculations. Some of these methods are preferred for three phase calculations, unless you have some interaction parameters to supply. The following summarizes the methods normally recommended for performing VLLE calculations.

Among the Liquid Activity methods, both NRTL and UNIQUAC have extensive LLE parameter data banks. UNIFAC also has capability to generate these predictions.

Among the Equations of State, several have extensive databanks of binary interaction parameters for water with light hydrocarbons and gases. These include the modified Panagiotopoulos - Reid (SRKM) and SimSci (SRKS) modifications to the SRK method, as well as the modified Panagiotopoulos - Reid (PRM) version of the Peng - Robinson equation . The SRK Kabadi-Danner (SRKK) method also generates parameters for water-hydrocarbon systems.