VLE Calculations

VLE calculations represent equilibrium between one vapor and one liquid phase. PRO/II contains a number of thermodynamic methods that can predict the K-values for these calculations.

A special case occurs when handling mixtures that form water as a nearly pure immiscible phase. Such systems are common in hydrocarbon-water mixtures in refinery and gas processing plants. For engineering purposes, it may often be assumed that the water phase is pure which reduces the computational time required to solve these simulations with rigorous VLLE models. When performing this calculation, PRO/II first seeks to satisfy the partial pressure of water as given in the steam tables. When the vapor phase is fully saturated and the hydrocarbon is saturated with water according to its water solubility, all remaining water is decanted into the pure water phase.