Rigorous energetic analysis of the pressure-swing distillation process

Abstract

Pressure-swing distillation is an important separation method and does not require external agents to promote the separation, thus making it a good option to minimize environmental impact. However, pressure-swing distillation must be optimized and energetically integrated, partially or fully, aiming to be competitive with other separation methods. Therefore, this work aims to perform an energy analysis of the pressure-swing distillation process through a new optimization procedure. The case study was selected based on the industrial importance of acetone-methanol separation, according to the consulted literature. Using Aspen Plus™ software, the low-high pressure configuration was implemented for comparison purposes in different integration configurations: without thermal integration and with partial and full thermal integration. For both configurations, the proposed optimization procedure allows to obtain better results when compared to the literature used as reference. Due to the ease of simulation convergence for configurations with partial and full thermal integration, which were initially simulated disregarding mass balance, the proposed procedure can be used with evolutionary optimization techniques. Furthermore, the effect of high pressure on the vapor-liquid equilibrium of the high-pressure column was evaluated, and the results showed that it is essential to consider the non-ideality of the vapor phase in that column, due to its strong influence on the liquid-vapor equilibrium.