Pressure Swing Batch Distillation for Homogeneous Azeotropic Separation

The separation of the homogeneous azeotropic mixture acetonitrile/water by pressure swing distillation (PSD) is considered. In this work, the PSD is operated as a discontinuous (batch) process and two basic batch modes, regular and inverted, are investigated. The processes are analysed and a rigorous dynamic model for both batch PSD processes is formulated. The model takes a cold and empty column as an initial condition. Because of the lack of experimental data, in particular for the inverted batch distillation new experiments were carried out. The regular and the inverted batch PSD consist of two steps, a low pressure and a high pressure run, and experimental results are shown for each step. The simulations fit the experiments with good accuracy. Using the validated model, a simulation study to discuss different batch processes is carried out and an alternative inverted batch process is proposed.