Design and control of an energy-efficient process for the separation of benzene/isopropanol/water ternary mixture
Journal
Separation and Purification Technology
Journal Volume
255
Date Issued
2021
Author(s)
Abstract
In a recent publication, a triple-column side-stream extractive distillation system was proposed for the separation of benzene/isopropanol/water ternary mixture using ethylene glycol as a heavy entrainer. However, the above design needs to introduce a foreign component into the separation task. In this paper, the newly proposed design principle is to make use of large liquid–liquid envelope together with pressure-sensitive distillation boundary of this ternary system for the development of an energy-efficient design consisting of a decanter and three columns operating at different pressures. In order to give reliable simulation results, a new set of UNIQUAC model parameters for this ternary system is obtained in this paper by regression from liquid-liquid and vapor–liquid equilibria data in open literatures. Simulation investigations reveal that significant savings of 63.4% in the total operating cost and 51.0% in the total annual cost can be realized by our proposed heat-integrated design flowsheet. Furthermore, overall control strategy of the proposed design has also been developed using closed-loop and open-loop sensitivity analyses for the determinations of crucial tray-temperature control points and also to make decision on holding which flow ratio(s) in the flowsheet to be fixed. Dynamic simulations demonstrate that the proposed overall control strategy is capable of holding three products at high-purity despite feed flow rate and feed composition disturbances. No online composition analyzer is required in the proposed control strategy. © 2020 Elsevier B.V.
Subjects
Energy-saving scheme; Liquid–liquid separation; Multiple azeotropes; Pressure-swing distillation; Process design and control; Ternary separation
SDGs
Other Subjects
Benzene; Benzene refining; Distillation; Distilleries; Energy efficiency; Ethylene; Ethylene glycol; Flowcharting; Liquids; Mixtures; Sensitivity analysis; Ternary systems; Design and control; Different pressures; Distillation boundaries; Energy-efficient design; Energy-efficient process; Extractive distillation systems; Integrated designs; Pressure sensitive; Distillation columns
Type
journal article