Design and control of a hybrid reactive extraction configuration for the production of tert-butyl alcohol

Abstract

Abstract In this study, the design and control of the hydration process for the production of tert-butyl alcohol (TBA) through a hybrid reactive extraction configuration was proposed. Firstly, TBA production by using a reactive distillation configuration and a hybrid reactive extraction configuration without the inert n-butene (NC4) was investigated. Due to the azeotrope between TBA and water (H2O), azeotropic distillation is required in the separation section with cyclohexane (CyH) as the entrainer. Compared to the reactive distillation configuration, the hybrid reactive extraction configuration was superior in terms of the total annual cost (TAC) and energy savings for the production of 99.9 mol% of TBA. Subsequently, the feed composition with the inert NC4 for a more realistic feeding condition was also investigated while using the hybrid reactive extraction configuration. The major differences in the two feed conditions were the compositions in the outlet of the reactive extraction section and the functions of the C1 column. Then, two control structures [a single-point temperature control (CS1) and a dual-point temperature control (CS2)] with three inventory control loops (inventory A–C) of the hybrid reactive extraction configuration with the inert NC4 were proposed. The simulation results revealed that both stoichiometric balance and liquid–liquid equilibrium (inventory C) in the RE column should be used for the dynamic operation. The CS2 with inventory C (CS2C) was found to be the optimal control strategy in this process.