ABSTRACT
An integrated part of chemical engineering is the calculation of phase equilibria. The importance of phase equilibria calculations is realized in designing the process equipment and optimizing separation and purification processes. The main objective of these calculations is to recognize the presence of one vapor or liquid, two vapor-liquid or liquid-liquid, or multiple phases. This chapter provides a detailed analysis of complex-phase behavior involving two liquid phases and one vapor phase simultaneously present, better known as the vapor-liquid-liquid equilibria (VLLE). Information regarding temperature, pressure and composition in vapor-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) is crucial for designing distillation and extraction processes. VLLE is frequently encountered in heterogeneous azeotropic distillation which is widely found in hydrocarbon industry. The heterogenic azeotropic distillation separates azeotropic mixtures into their components. The chapter highlights the experimental and computational techniques used for VLLE.
