SIMULATION, DESIGN, AND ANALYSIS OF AZEOTROPIC DISTILLATION OPERATIONS

The computational tools needed for simulation, design, and analysis of azeotropic distillation operations are described. These tools include simple methods to identify the existence of binary and ternary azeotr opes and to classify ternary mixtures as homogeneous or heterogeneous. The tools also include more complex methods to compute the phase diag ram (or a heterogeneous liquid boiling surface), predict liquid-vapor phase equilibrium, and/or predict liquid-liquid-vapor phase equilibriu m for simulations of batch and continuous distillation column operatio ns. Important new features of these tools are the incorporation of a f ast and efficient method for test of phase stability in simulation of distillation operations, the ability to handle a large range of mixtur es (including mixtures with supercritical compounds), and the ability for computations covering wide ranges of temperature and pressure. On the basis of these tools, simple and consistent design algorithms are developed. The applicability of the design algorithms is verified thro ugh process simulation and analysis of the predicted behavior and data from the open literature. Conditions are given for examples illustrat ing (when and how possible distillation boundaries can be crossed) how multiple steady states can be obtained. Finally, the effect of change s in operating conditions on the dynamic behavior of the azeotropic di stillation columns and the sensitivity of design to the prediction of phase equilibria are presented.