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• A systematic framework towards sustainability is proposed to separate methanol and trimethoxysilane azeotrope. • Three distillation processes are optimized through MADS method for single-objective optimization. • A heat pump-assisted EDWC process (HP-EDWC) is optimized through multi-objective NSGA-II algorithm. • A multi-criteria decision-making method of TOPOSIS is proposed to give the optimal solution. The design and optimization of distillation process for separating azeotropes has attracted extensive attentions in decades. Currently, due to the high emphasis on environmental and social effect, it is necessary to incorporate relevant criteria into the objective function in addition to the economic indicators for approaching a more sustainable process. This paper aims to improve the process for separating the azeotropic mixture of methanol and trimethoxysilane via multi-objective optimization based on NSGA-II. Firstly, the performance of three processes, i.e., pressure-swing distillation, extractive distillation, and extractive dividing wall column (EDWC) distillation, is optimized and compared by using total annual cost (TAC) as the objective function, demonstrating that the EDWC distillation process is the preferred process. Subsequently, a heat pump assisted EDWC process (HP-EDWC) is proposed, and the multi-objective optimization is carried out based on NSGA-II algorithm with three criteria including TAC, carbon emission, and the thermodynamic efficiency, to obtain a set of Pareto solutions, which are then evaluated by using a multi-criteria decision-making method of TOPSIS to give the optimal solution. As a result, the values of TAC, carbon emission, and thermodynamic efficiency of the optimal HP-EDWC process are 90.30×104 $/year, 501.07 kg/h, and 26.02%, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

• ED processes for separating 1,2-dichloroethane and n-hexane mixture were developed. • Two heat pump enhanced ED processes were proposed and optimized. • TAC of the heat pump enhanced ED processes is decreased. • Energy efficiency of the ED processes can be improved by employing HP technology. In the industrial process to synthesize ethylene sulfate, a film-forming electrolyte additive for lithium-ion batteries, a significant amount of liquid mixtures of n -hexane (HE) and 1,2-dichloroethane (DCE) are generated, whose separation is challenging because of the formation of a minimum-boiling azeotrope. Hence, in this study, the conventional ED process for separating the HE/DCE mixtures was firstly investigated. Subsequently, since the temperature difference between the overhead vapor and bottom liquid is large, which is not favorable to the application of the vapor recompression heat pump technology, two bottom flash heat pump (HP) assisted extraction distillation (ED) processes, i.e., the bottom flash HP assisted ED (BFHP-ED) process and the coupled vapor recompression and bottom flash HP assisted ED (VRBFHP-ED) process are proposed and optimized in terms of the minimal total annual cost (TAC). The results show that, the thermodynamic efficiency increases from 7.63% for ED, to 13.76% for BFHP-ED, and 13.16% for VRBFHP-ED processes, while CO 2 emissions of the BFHP-ED and VRBFHP-ED processes can be reduced by 41.05% and 39.19%, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

• Model predictive control (MPC) of extractive dividing-wall column (EDWC). • Separation of toluene and 2-methoxyethanol using dimethyl sulfoxide as entrainer. • Closed-loop identification of linear dynamic model for implementing MPC for EDWC. • Control by MPC using identified or linearized model is comparable to or better than PI. • Same steady state by MPCs using direct or indirect manipulation of vapor split ratio. Extractive dividing-wall column (EDWC) is a promising thermally-coupled system for separating multiple azeotrope or close-boiling mixtures; however, its intensified structure with relatively small physical space and strong interactions makes model predictive control (MPC) an attractive scheme for EDWC operation. The performance of MPC strongly depends on the accuracy of the dynamic model. The presence of recycled entrainer stream in EDWC makes it impossible to identify the dynamic model of EDWC using open-loop experiments. In the present study, a proportional-integral (PI) control strategy based on temperature difference was first studied for EDWC operation. Subsequently, a systematic closed-loop identification experiment was implemented to identify a dynamic model, and an MPC was designed using the identified model. The results indicate that the accuracy of the identified model is sufficient to design MPC controller for EDWC operation. Both direct and indirect manipulation of vapor split ratio were considered in MPC. The transient responses of product purities indicate that MPC is better than PI for EDWC operation for rejecting disturbances in feed flow rate and composition, even though MPC shows slow dynamic responses compared to PI control for rejecting feed composition disturbances. [ABSTRACT FROM AUTHOR]