Multi-Objective Optimization And Control Strategy For Extractive Distillation With Dividing-Wall Column/Pervaporation For Separation Of Ternary Azeotropes Based On Mechanism Analysis

Cyclohexane and isopropanol (IPA) are commonly used as solvents for rapeseed oil peeling and low-temperature pressing. Owing to the existence of azeotropes, it is difficult to achieve efficient separation of wastewater by ordinary distillation. The theory of thermodynamics and molecular dynamics was used to explore the separation mechanism and identify optimal extractants. Furthermore, extractive dividing-wall column and pervaporation (PV) technology were used to decrease the energy consumption in the recovery process. Thermodynamic performance and environmental assessments were used to analyze the processes. Taking the total annual cost (TAC) and exergy as the objective, the processes were optimized by multi-objective optimization. The results showed that the TAC and CO2 emissions of the extractive dividing-wall column process were reduced by 7.46% and 5.89%, compared with the basic process. The TAC and CO2 emissions of the PV extractive distillation process were reduced by 13.98% and 15.09%. On this basis, the dynamic control performance was further explored by introducing a +/- 10% feed flow and composition disturbance. In addition, the influence of the composition on the economics of PV and distillation was studied. It was found that the PV-extractive distillation process has significant advantages over the basic process in the separation of azeotropes. (C) 2021 Elsevier Ltd. All rights reserved.