Synthesis and simulation of a distillation columns system for the propylene glycols mixtures separation

Abstract

Abstract Four sequences were synthesized and simulated for the separation process of the propylene glycols mixtures: the direct, the indirect, and two proposed sequences. The simulation of the distillation columns system was performed with PRO/II program using a complete NRTL (nonrandom two‐liquids) thermodynamic model. Two mixtures were subject of the separation: one containing only propylene glycols, and another containing in addition a significant amount of water. The disadvantage of the direct and indirect sequences is that the columns are operated at high temperatures in the bottoms this fact leading to decomposition of propylene glycols. The proposed separation sequences aim to eliminate this disadvantage by taking into account the nearest effect of inert gas that water and propylene glycols with lower molar mass have on the separation mixture. The feed is introduced directly in the reboiler of the first column, where lower glycols and water act as an inert gas on the TePG vaporization. The proposed separation sequence of the propylene glycols and water mixture has a temperature in the reboiler with approximately 13 K lower beside the direct sequence.

Keywords

• distillation
• propylene glycols
• separation, simulation
• synthesis