ROBUST FLASH CALCULATION ALGORITHM FOR MICROEMULSION PHASE BEHAVIOR

摘要

The HLD-NAC model was recently modified to match and predict microemulsion phase behavior experimental data for Winsor type III regions. Until now, the HLD-NAC model cannot generate realistic phase behavior for type II− and type II+ two-phase regions, leading to significant saturation and composition discontinuities when catastrophe theory is applied. These discontinuities lead to significant failures in modeling surfactant applications. The HLD-NAC equations are modified to ensure consistency over the entire composition space including type II− and II+ regions. A robust and efficient algorithm is developed that always converges and provides continuous estimates with any formation variable of tie lines and triangles for all Winsor types. Discontinuities are eliminated and limiting tie lines near critical points are determined analytically. The tuning procedure is demonstrated using several sets of experimental data. Excellent predictability of tie lines and tie triangles, and solubilization ratios are shown.