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Background: Presently, there are no studies that examine the impact of side‐reactions of ethylene oxide hydration on triple‐column reactive‐extractive distillation (TC‐RED). This study addressed this gap by investigating how these side‐reactions influence the energy consumption, total annual cost (TAC), and CO2 emission of the TC‐RED process. Two case studies, which involve the ternary separation of tetrahydrofuran (THF)/ethanol (ETOH)/water and ethyl acetate (EA)/ETOH/water were conducted here. Results: Case studies 1 and 2 showed significant increase in energy consumption (39.68% and 16.56%), TAC (65.57% and 47.88%) and CO2 emission (21.15% and 12.89%) resulting from side‐reactions. The increase in energy consumption, TAC, and CO2 emission is primarily a consequence of the high boiling point of higher glycol product derivatives, altered chemical equilibrium behavior and increased reactant flowrates, which necessitate larger equipment sizes and incur higher capital costs. Notwithstanding this, TC‐RED with side‐reactions still outperforms pressure swing distillation (PSD) for separation of THF/ETOH/water and extractive distillation (ED) for separation of EA/ETOH/water. However, it falls short of double‐column reactive‐extractive distillation (DC‐RED) owing to the need for an additional column. Conclusion: Our study highlights the importance of considering side‐reactions in TC‐RED during process design. Although the decline in performance is a result of the additional complexities brought by side‐reactions, it is important to emphasize that the primary takeaway of this study is that the system model is more realistic. By incorporating side‐reactions into the simulation, we can model the system more comprehensively, providing future researchers with an opportunity to explore and address potential issues resulting from side‐reactions. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

BACKGROUND: The sustainability performance of extractive distillation (ED) that collectively considers energy efficiency, process safety, economic profitability, process control, and environmental emission has not been widely reported. Motivated by this lack of research, we analyzed and compared the sustainability performance of the intensified side‐stream ED (SSED) with that of the conventional extractive distillation (CED) for the separation of binary azeotropic mixtures. Two different design approaches were analyzed; the first approach involves designing the intensified SSED by preserving the original CED column configuration, while the second approach involves optimizing the original column configuration to become a new intensified SSED configuration. RESULTS: We found that preserving the original configuration usually provides energy‐savings, but this advantage is not guaranteed unless the process is optimized. Generally, the reduction in energy consumption improves economic and environmental performance. However, the optimized design has a higher risk index because it is usually larger in size, for the sake of lowering the energy consumption. In addition, the optimized design usually has a higher condition number, which signifies that a more complex control structure is required. CONCLUSION: Altogether, designing the intensified process via process optimization does not always guarantee significant improvement in all sustainability indicators. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

BACKGROUND: Here, we investigated the control performance of extractive distillation intensified with 'feed split' (FS) technique – a process intensification technique that has not been widely applied to extractive distillation. Today, only a handful of studies have been reported on this topic, with only one focusing on the control performance and reporting the significant trade‐off between the steady‐state and dynamic performances. Nonetheless, the previous control study was based on the complex double column FS configuration. Recently, a new triple column FS configuration was reported (Sep. Purif. Technol. 2022 (297) 121467), but its control performance was not investigated. Hypothetically, the triple column FS configuration is less complex and does not involve any column integration and thus, may demonstrate a better dynamic performance. This study analyzed the control performances of the triple column FS configuration and the conventional configuration for the binary azeotropic separation of tetrahydrofuran and ethanol. RESULTS: Two types of control structures were examined for both configurations, i.e., the basic temperature control structure and the different feed forward temperature control schemes. The best control structure from each configuration is compared and findings showed that the conventional configuration provides better controllability performance. CONCLUSION: Our results suggested that the conventional configuration can bring the product qualities closer to their setpoint, while providing a lower transient deviation. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Background: Here we analysed the possibility of improving the sustainability performance for the recovery of dichloromethane and methanol from a binary azeotropic mixture using different energy‐intensified extractive distillation‐based processes: side‐stream extractive distillation (SSED), thermally coupled extractive distillation (TCED), and extractive dividing wall column (EDWC). The sustainability performance of the different processes was analysed based on three main factors: total annual cost (TAC), CO2 emissions, and condition number. Results: The EDWC was found to give the best improvement in terms of TAC and CO2 emissions by about 18% and 21%, relative to conventional extractive distillation (CED). These however were traded‐off by the increase in conditional number (CN) by 186 times, signifying a complex dynamic characteristic for the EDWC. Thus, the SSED was suggested as an alternative sustainable option as it also provides significant improvement in TAC and CO2 emissions by about 11%, and 18% with respect to the CED, whilst providing the least reduction in operational controllability, as evidenced by the marginal increase in the CN of about 1.5 times. We also investigated the dynamic performance of the SSED and found that the SSED provides identical dynamic performance in handling both ±10% throughput and ±5% feed composition disturbances as those of the CED. Conclusion: Among the different processes, SSED is the best sustainable alternative that provides compromised steady‐state (i.e. TAC and CO2 emissions) and dynamic (i.e. control) performance for the recovery of dichloromethane and methanol. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

• A novel heterogeneous triple-column distillation (NHTCD) without solvent injection. • Simplification of previously established extractive distillation (ED) process. • Enhanced with heat integration (HI) and heat pump-vapor recompression (HP-VR). • HP-VR with HI NHTCD provides 87 %, 57 %, and 86 % lower energy, cost, and emission. • Conceptual design based on thermodynamic insights. The challenging separation of ethyl acetate (EtAC) and methanol (MeOH) from wastewater involves two azeotropes and a distillation boundary. Although extractive distillation (ED) has been explored, the heterogeneous region within the ternary azeotropic mixture has been overlooked, which suggests the possibility of using a decanter to cross the distillation boundary when the feed composition is present in the heterogeneous region. This study introduces a novel heterogeneous triple-column distillation (NHTCD) that eliminates the external solvent injection, simplifying the complex ED processes. The NHTCD process is developed via a systematic approach, comprising conceptual design based on thermodynamic insights and process optimization to determine the optimum configuration. Furthermore, heat integration (HI) and heat pump-vapor recompression (HP-VR) techniques were explored for energy conservation. Evaluation of energy, economic, and environmental (3E) aspects shows that the hybrid HP-VR with HI NHTCD process outperforms ED, achieving 87 %, 57 %, and 86 % reductions in energy, economic, and environmental emissions, respectively. [ABSTRACT FROM AUTHOR]

• Basic control structure of double side-stream extractive distillation is designed. • F/SS and Q R /F feedforward structures are explored for better control performances. • A robust control strategy CS4 is proposed to obtain the desired product purities. The investigation of dynamic controllability for the double side-streams ternary extractive distillation (DSTED) is necessary due to its advantages in energy-efficient. However, the control strategy of the energy-saving DSTED scheme is unique and complex issues owing to the wobbly of side-stream flow rate. Herein, control strategy of the energy-saving DSTED scheme is explored for separating ternary azeotropic mixtures acetonitrile/methanol/benzene. Inspiring from the control strategy of the ordinary triple-column extractive distillation scheme, the fundamental control structure CS1 is firstly designed. The control scheme CS2 with feed/side-stream (F/SS) ratio and control structure CS3 with feedforward and F/SS are then investigated to achieve higher efficiency of process control. Finally, a robust control strategy CS4 with the ratio of reboiler duty and feed flow rate and without F/SS ratio is proposed to well maintain the product purities. Moreover, additional ±15% feed flow rate and composition disturbances are added in the CS4 to assess the stability and controllability of the energy-saving DSTED. Dynamic performances illustrate that the structure CS4 can handle as well as that of confronted ±10% disturbances when the large disturbances are occurred in the real chemical process. [ABSTRACT FROM AUTHOR]

• A systematic design procedure is proposed for the four-azeotrope mixture separation. • The conceptual design including residue curve maps on two schemes is investigated. • The control strategies is proposed for the DEDP process with economic superiority. • An improved control structure combining proportion with "HiLoSelect" is developed. The separation of ternary mixtures with homogeneous or heterogeneous multi-azeotropes has received increasing attention. In this work, a systematic design, optimization and control procedure is proposed for extractive distillation of heterogeneous mixtures with four azeotropes. Herein, the ternary system isopropyl alcohol/isopropyl acetate/water is taken as a case study. The suitable entrainer is first obtained through a proposed approach combining the vapor–liquid equilibrium (VLE) curves and infinite dilution activity coefficient ratios. Conceptual design of two alternative separation sequences involving double-column extractive distillation with a pre-concentrator (DEDP) and triple-column extractive distillation (TED) are then investigated based on thermodynamic insights. With the method of sequential iterative optimization and taking total annual cost (TAC) as the objective function, the two processes are optimized. The optimal results indicate that the DEDP process with dimethyl sulfoxide as entrainer can save 6.43% TAC than that of TED. Finally, a new control structure combining reflux flowrate-to-feed (R/F) and adjustable reboiler duty-to-feed (Q R /F) with "HiLoSelect" strategy is proposed to better handle three product purities than that of the basic control structure while feed flowrate and composition disturbances are introduced in the studied DEDP process. [ABSTRACT FROM AUTHOR]

The separation of ternary nonideal systems with multi‐azeotrope is very important because they are often found in the waste of chemical and pharmaceutical industries, which is much more difficult due to the formation of multi‐azeotrope and distillation boundary. We propose a systematic procedure for design and control of a triple‐column pressure‐swing distillation for separating ternary systems with three binary minimum azeotropes. This procedure involves thermodynamic insights, a two‐step optimization method, and effective control strategy. The separation of tetrahydrofuran (THF)/ethanol/water is used to illustrate the capability of the proposed procedure. It is found that the pressure limits in columns can be determined through the analysis of residue curve maps, distillation boundary, and isovolatility curves. The optimal triple‐column pressure‐swing distillation is generated with the minimum total annual cost (TAC) of $2.181 × 106 in sequence A. The operating conditions are well controlled approaching their desired specifications in an acceptable time when disturbances occur. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1281–1293, 2019 [ABSTRACT FROM AUTHOR]

• The suitable entrainer is screened via the thermodynamic insights. • Development of intensified extractive distillation with side-reboiler. • Optimization of proposed process using multi-objective particle swarm algorithm. This work explores the recovery of ethyl acetate (EtAC) and methanol (MeOH) from wastewater stream using three different extractive distillation (ED) processes, i.e., the triple-column ED (TCED), four-column ED (FCED), and the energy-intensified TCED with side-reboiler (TCED-SR). All the three processes are conceptually designed and then optimized using multi-objective particle swarm optimization with total annual cost (TAC), CO 2 emission, and process route index (PRI) as objectives. Altogether, the TCED-SR is recommended to provide the best economic and environmental performances, as reflected by the lowest TAC and CO 2 emission. It provides 34% and 20% lower TAC relative to TCED and FCED, respectively. Additionally, the CO 2 emission is 39% and 17% lower with respect to the TCED and FCED. In the places where safety requirement is strictly regulated, the FCED is recommended since the PRI for the TCED-SR is high, which denotes that the process should be operated with care. However, the TAC and CO 2 emission for the FCED is higher by about 21% and 36% with respect to the TCED-SR while it is lower than the TCED by about 20% and 17%, respectively. [ABSTRACT FROM AUTHOR]

• Control of indirect extractive distillation for ternary azeotropic separation. • Control performance comparison between single and dual temperature control (TC) • A case study of tetrahydrofuran, ethyl-acetate, and water azeotropic separation. • The feed forward dual TC provides better control performance than the single TC. Most of the design and control studies for extractive distillation of the ternary azeotropic separation today focus only on the direct sequence extractive distillation (DED) while the design study for indirect sequence extractive distillation (IED) is rarely reported. Furthermore, there is no control study that worked on the IED. To bridge this gap, we analyze the control performance of the heat-integrated (HI) IED, exemplified using the separation of tetrahydrofuran (THF)/ethyl acetate (EtAc)/water as a case study. A single point temperature control (TC) (CS 1), dual TC (CS 2), and feed forward dual TC (CS 3) are developed in this work and their performances in rejecting feed flow and composition disturbances are tested. Overall, CS 3 exhibits the best control performance in returning all the three products purities to a value close to the products specification and provides the lowest transient deviation under feed flow and composition disturbances. The CS 3 also provides the lowest sum of integral absolute error with respect to CS 1 and CS 2 , further reflecting its dynamic superiority. [ABSTRACT FROM AUTHOR]

Incorporating sustainability metrics into the design of economically viable and environmentally responsible processes is crucial for achieving overall sustainability. Reactive distillation has been widely studied in this context, but studies on extractive distillation have been limited, particularly in ternary azeotropic separation. This study aims to address this gap by integrating green sustainability metrics into extractive distillation through multi-objective optimization, considering economic, environmental, and safety indicators simultaneously. The results showed that our approach resulted in greater sustainability improvements compared to a sequential approach, where optimization was initially based on economic objectives with the environmental and safety aspects evaluated subsequently. The optimized configurations for ethanol, tetrahydrofuran, and methanol separation using three column extractive distillation and four column extractive distillation in this work showed significant sustainability improvements compared to their base cases. Specifically, three column extractive distillation outperformed four column extractive distillation in energy, economic, environmental, and safety performance by 18%, 4%, 8%, and 18%, respectively. • Incorporation of sustainability metrics for design of extractive distillation (ED). • Multi-objective optimization (MOO) involving economic, environmental, and safety. • Result comparison with MOO using capital and operational cost as objective function. • Result comparison against sequential approach for sustainability evaluation. • Present approach provides better sustainability relative to a sequential approach. [ABSTRACT FROM AUTHOR]

• Development of novel side-stream hybrid reactive-extractive distillation (SS-DCRED). • Resource recovery of isopropanol and ethyl acetate from wastewater. • Benchmark against the established reactive-extractive dividing wall column (REDWC). • Performance comparison against conventional extractive distillation (CED). • SS-DCRED provides the lowest energy, TAC, and environmental emissions. For the first time, we developed a novel side-stream double-column reactive-extractive distillation (SS-DCRED) for the recovery of isopropanol (IPA) and ethyl acetate (EA) from wastewater. Starting with the conceptual design and optimisation of a double-column reactive-extractive distillation (DCRED) using particle swarm optimisation (PSO), we designed and optimised next the SS-DCRED, which is the main contribution of this work. In addition, a reactive-extractive dividing wall column (REDWC) was also developed as we intend to benchmark the SS-DCRED with the REDWC, which is available in literature. The performance of the SS-DCRED was also compared against the DCRED and the best heat-integrated conventional extractive distillation (HI-CED) using ionic liquid (ILs) and ethylene glycol (EG) from previous work based on total energy consumption, TAC, environmental performance, and thermodynamic efficiency. Overall, the total energy consumption, TAC, and environmental performance of the SS-DCRED are 51%, 40%, and 51% lower with respect to the HI-CED using ILs and are 63%, 56%, and 63% lower than the HI-CED using EG from previous work. Likewise, it is also better than the REDWC by about 8%, 4%, and 9% in terms of total energy consumption, TAC, and environmental emissions with respect to the REDWC. These significant enhancement highlights the superiority of our proposed SS-DCRED. [ABSTRACT FROM AUTHOR]

• Recovery of high purity tetrahydrofuran and ethyl acetate from waste water. • Development of a hybrid vapor recompression side-stream ED for energy saving. • The hybrid process provides lowest TAC, CO 2 emission, and energy consumption. • The hybrid process provides highest thermodynamic efficiency. The energy-efficiency of the traditional distillation-based processes are low, which results in waste of resources and environmental pollution. Therefore, a sustainable extractive distillation (ED) process should be developed to reduce energy consumption and CO 2 emissions while improve the energy efficiency. In this work, a systematic approach is developed for the first time, for the separation of ternary azeotropic mixture containing Tetrahydrofuran (THF)/Ethyl acetate (EtAC)/Water via the combination of side-stream distillation and vapor recompression heat pump techniques. Firstly, the conceptual design of the various intensified schemes such as single (or double) side-stream(s) ED configurations are developed. Subsequently, the developed configurations were optimized using mesh adaptive direct search algorithm to obtain the optimal operating conditions of the established processes. Vapor recompression heat pump technique is used to further reduce the energy consumption. The sustainability of the various established configurations is assessed via the comparison of total annual cost (TAC), CO 2 emissions, energy consumption, and thermodynamic efficiency. Overall, it was revealed that the TAC, CO 2 emissions, and energy-consumption for the integrated vapor recompression assisted side-stream ED process were reduced by 33%, 49%, and 38%, respectively, relative to the conventional triple column ED. Likewise, the thermodynamic efficiency was improved by 52%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two energy-efficient separation processes are developed via thermodynamic insights. • Multi-objective particle swarm algorithm is used to optimize the proposed processes. • Direct triple-column extractive distillation process has better performances. Sustainable process for the separation of ternary azeotropic mixture tetrahydrofuran/ethanol/methanol should be developed to recycle value-added organic components and protect environment. Thereby, in this work, we propose an approach to develop a sustainable process for the recovery of these valuable compounds from their ternary azeotropic mixture. The suitable entrainers of direct and indirect extractive distillation processes are firstly screened via the thermodynamic insights (e.g. , volatility line). Next, the separation sequence for the developed extractive distillation processes is determined by combining the residue curve maps, volatility order, and Lever rule. Then, the multi-objective particle swarm optimization algorithm is employed to obtain the established processes with optimal operating parameters via the integration of Matlab and Aspen Plus. Eventually, four indexes include total annual cost, CO 2 emissions, process route index, and thermodynamic efficiency, which are used to assess the economic, environmental, safety, and energy efficiency performances. Relative to the indirect process, the direct extractive distillation sequence, in particular, provides 15.61%, 9.75%, and 48.4% reduction in total annual cost, CO 2 emission, and inherent safety, respectively, while it improves the energy efficiency by 29.7%. [ABSTRACT FROM AUTHOR]

The separation of ternary azeotropic systems has received significant interest as it enables the recovery of value-added organic solvents, subsequently contribute towards environmental protection. In this work, we propose a novel approach that involves the conceptual design, multi-objective optimization, and process evaluations for developing two different processes, i.e., double-column reactive-extractive distillation (DCRED) and reactive-extractive dividing wall column (REDWC), for the separation of ethanol/ tert -butanol/water ternary azeotropic mixture. The conceptual design of the proposed processes was conducted using kinetic and thermodynamic analysis while optimal operating conditions of the established processes were obtained via multi-objective particle swarm optimization algorithm. Then, both developed processes were evaluated based on the total annual cost (TAC), CO 2 emissions, and thermodynamic efficiency. From the steady-state simulation, DCRED and REDWC provides a TAC of 1.056 × 106 US$ and 1.117 × 106 US$, respectively. Likewise, it provides CO 2 emissions of 731.27 kg/h and 733.42 kg/h, respectively. The energy efficiency of the DCRED and REDWC were found to be 1.285% and 1.055%, respectively. Relative to the conventional extractive distillation process, the TAC and CO 2 emission for the proposed DCRED reduced significantly by 55.4% and 61.8%, respectively. Similar reduction was also observed for the REDWC which provides 52.8% and 61.7% lower TAC and CO 2 with respect to the conventional process. In addition, the thermodynamic efficiency of the developed DCRED and REDWC processes are improved by 40.4% and 15.3% in comparison to the conventional extractive distillation scheme. [Display omitted] • Sustainable reactive assisted extractive distillation processes are proposed. • Multi-objective particle swarm algorithm is used to optimize the proposed schemes. • The proposed reactive-extractive distillation schemes have better 3E performances. [ABSTRACT FROM AUTHOR]

This perspective paper features the process intensification (PI) application for advanced distillation-based processes. Starting with the historical background of generic PI, we subsequently narrow down the discussion to extractive distillation (ED), reactive distillation (RD), and hybrid reactive-extractive distillation (RED). We categorize the existing PI techniques onto internal and external intensification, where the former does not involve altering the distillation configuration while the latter does. Instead of deliberating the technical aspects, we explicitly highlight the contribution of PI applied to ED, RD, and RED towards societal impact covering energy, economic, environmental, control, and safety perspectives. The future perspectives of PI are discussed in the last section, covering the development of hybrid PI technologies, exploring the energy efficiency of different PI configurations, prioritizing PI beyond energy by considering some other sustainability aspects, and linking PI with the ever-increasing Industry 4.0 applications. • Historical application of PI of conventional distillation. • Extension of PI to advanced distillation processes covering ED, RD, RED. • Categorization of internal and external PI techniques. • Contribution of PI to sustainability and societal impact. • Future perspectives of PI applied to ED, RD, and RED. [ABSTRACT FROM AUTHOR]

In this work, a systematic method for conceptual design and multi-objective optimization of an energy-efficient and sustainable reactive/extractive distillation (RED) process is proposed to separate a ternary wastewater mixture with multi-azeotrope tetrahydrofuran/ethanol/water. Conceptual design of the proposed scheme is carried out by the analysis of thermodynamic feasibility (e.g., residue curve maps and iso-volatility line). In the proposed process, the component of water in the ternary system is firstly removed by adding the reactant in a reactive distillation column and the remaining binary azeotropic mixture is then separated via ED. During the ED process, the best entrainer dimethyl sulfoxide could be determined via the comparison of iso- and uni-volatility. An improved multi-objective genetic algorithm is employed for optimizing the established process with some key decision variables (e.g., feed locations and distillate rate). The results illustrated that the economic and environmental benefits of the proposed RED process will be greatly improved. Image 1 • A sustainable and cleaner reactive/extractive distillation process is proposed. • The entrainer is screened by the thermodynamic feasibility insights. • The proposed process is optimized based on the improved genetic algorithm. • The proposed process has better economic and environmental performances. [ABSTRACT FROM AUTHOR]

• A dual temperature control scheme is proposed to control the product purities. • Two temperature difference control schemes are used to improve the control effect. • Energy consumption is added to evaluate the controllability of control schemes. • Temperature difference control scheme shows the best dynamic control performances. The exploration of control strategy for the double side-stream ternary extractive distillation (denoted as DSTED) process is essential because it has a significant potential for energy-saving. However, how to effectively control the energy-efficient DSTED process is a unique and complex issue due to the additional coupled variables of double side-streams. Consequently, in this study, control schemes of the energy-efficient DSTED process for separating acetonitrile/methanol/benzene with multi-azeotrope are investigated. Firstly, a dual-temperature control strategy is proposed based on the existing single temperature control with feedforward scheme. Temperature difference control strategy is then studied to effectively reduce the offset of product purities for the disturbances of feed composition. Following that, a double-temperature difference control strategy is studied to maintain the product purities. Finally, the comparisons of product purities and energy consumption are introduced to clearly assess the stability and controllability of the different temperature control structures. Dynamic performances show that the temperature difference control structure has the best performance facing the ±10% feed disturbances. [ABSTRACT FROM AUTHOR]

• Effect of pressure on the amount flow rate of entrainer is investigated. • An energy-efficient extractive distillation is proposed for separating EtOH and DMC. • The energy consumption of the proposed process could be significantly reduced. • Heat integrated extractive distillation process is proposed to further save energy. An energy-efficient extractive pressure-swing distillation process is proposed for separating binary minimum azeotropic mixture ethanol and dimethyl carbonate. It can be observed that the minimum amount flow rate of entrainer will be decreased when the operating pressure of extractive distillation column is increased via the thermodynamic feasibility insights (i.e., residue curve map and isovolatility lines). Therefore, an extractive pressure-swing distillation process with 4 bar for the extractive distillation column is designed. Process variables of the proposed design are optimized by combining the sensitivity analysis and sequence quadratic program approaches with minimum total annual cost as objective function. Total annual cost, CO 2 emissions, and exergy loss of the optimized extractive pressure-swing distillation with 4 bar for the extractive distillation column is reduced by 44.09%, 44.16% and 41.54%, respectively when compared with the existing process with 1 bar for the extractive distillation column, which mainly attributing the flow rate of entrainer decreasing from 200.020 kmol/h to 44.963 kmol/h. Furthermore, the extractive pressure-swing distillation with heat integration is studied to further reduce energy cost because the enough heat transfer temperature difference could be provided by increasing operation pressure. [ABSTRACT FROM AUTHOR]

An intensified scheme for the separation of ternary azeotropic system is explored to reduce the energy consumption and recycle important organic solvents. Herein, a novel double-thermally coupled ternary extractive distillation (DTCTED) for separating azeotropic system benzene/toluene/cyclohexane (denoted as B/T/CH) is proposed to achieve energy-saving and emissions reduction. Thermodynamic feasible insights of the B/T/CH using dimethyl formamide as entrainer are firstly analyzed via residue curve maps to find separation constraints. Following that, the proposed intensified scheme is optimized via the in-house multi-objective genetic algorithm software while using total annual cost and CO 2 emissions as objective functions. The results show that the total annual cost and CO 2 emissions of the proposed intensified DTCTED scheme are significantly reduced by 18.60% and 20.22% compared with the existing single-thermally coupled ternary extractive distillation process. Furthermore, exergy loss and relative volatility are introduced to explore the essence of energy-saving in the proposed DTCTED scheme. • An intensified double-thermally coupled ternary extractive distillation is proposed. • The proposed scheme is optimized based on the multi-objective genetic algorithm. • Proposed scheme can save 18.60% and 20.22% of total annual cost and CO 2 emissions. • Essence of the energy-saving is explored by exergy loss and relative volatility. [ABSTRACT FROM AUTHOR]

In order to effectively separate complex azeotropic mixtures, it is crucial to consider economic, environmental, and safety factors during the process design and optimization. This study presents a systematic approach to separate a ternary azeotropic mixture of tetrahydrofuran, methanol, and water by employing multi-objective optimization and multi-criteria decision making. Two energy-efficient configurations, i.e., double-column reactive extractive distillation and reactive-extractive dividing wall column, are proposed by integrating reaction and extractive distillation in a single unit. The developed processes are then optimized using a multi-objective particle swarm optimization algorithm, considering the aforementioned factors. Finally, a multi-criteria decision making technique is applied to rank the Pareto frontier solutions obtained from the optimization process, using a combination of gray relational analysis and entropy weight method. Compared to the base case, the double-column reactive extractive distillation process exhibits a significant reduction in total annual cost (59.39 %) and CO 2 emissions (61.75 %). Through comprehensive evaluation, the double-column reactive extractive distillation process is found to be the most effective separation solution among the proposed and existing processes. This systematic approach can be extended to other complex aqueous azeotropic systems for their design, optimization, and decision making. [Display omitted] • A systematic approach for separating complex azeotropic mixtures is proposed. • Two intensified reactive-extractive distillation schemes are developed. • The developed processes are optimized via MOPSO algorithm. • The GRA combined with entropy weight is used for multi-criteria decision making. [ABSTRACT FROM AUTHOR]

• Three SSED processes are proposed to for the separation of ACN/EtOH/water system. • The trade-offs between economy, environment and safety of SSED are investigated. • The multi-criteria optimal process is determined by the TOPSIS with objective weights. • The energy-saving mechanism of proposed SSED processes are discussed. Side-stream extractive distillation is used in separating azeotropic mixtures due to its advantages in energy-saving. However, environmental and safety aspects should also be considered in most chemical industries. Thus, this work focuses on thermodynamic analysis, multi-objective optimization and multi-criteria decision making. The main contributions of this work are developing the intensified side-stream extractive distillation for complex ternary azeotropic mixture, obtaining the trade-offs between the economic, environmental and safety impacts of SSED processes and determining the best sustainable SSED process according to objective mathematical analysis. A systematic intensified architecture including conceptual design, multi-objective optimization and multi-criteria decision making is proposed. Firstly, three strategies of side-stream extractive distillation (i.e. , SSED-1, SSED-2, and SSED-3) are proposed via the thermodynamic analysis including quaternary phase diagram. Subsequently, the three strategies are optimized via the multi-objective particle swarm algorithm simultaneously using total annual costs (TAC), CO 2 emission and process route index (PRI) as objective functions. Finally, the optimal economic, environmental and safety performance of such a complex system is determined by the technique for order of preference by similarity to ideal solution method with entropy weighting information. The results indicate that the introduction of the side-stream for extractive distillation could decrease the exergy loss and increase the thermodynamic efficiency. The SSED-1 process shows that the best performance in economic, safety and environmental aspects, which reduce 19.21% of TAC, 5.24% of PRI and 16.80% of CO 2 emission, respectively. [ABSTRACT FROM AUTHOR]

• Dynamic performance comparison of extractive distillation (ED) using DMF and NMP. • The ED using DMF provides the best economic, environmental, and dynamic performance. • The ED using DMF is retrofitted to an energy-intensified side-stream ED. • The side-stream ED provides the lowest energy consumption, CO 2 emission, and TAC. • The side-stream ED also provides the best dynamic performance. In this work, we explored, for the first time, the possibility of improving the performance of conventional extractive distillation (CED) for the separation of n-hexane and ethyl-acetate system using dimethylformamide (DMF) as solvent through retrofitting it to an energy-intensified side-stream extractive distillation (SSED). This is since the application of the energy-intensified processes have never been explored in any of the existing studies for the n-hexane and ethyl-acetate system using DMF as solvent. Prior to the investigation, we first bridged the gap of previous study (Ind. Eng. Chem. Res. 2018, 57, 32, 11050–11060) where using DMF was found to be more economical relative to using n-methyl-2-pyrrolidone (NMP) as solvent but previous study did not explicitly compared the environmental and dynamic performances of both processes. The environmental performance evaluated based on the CO 2 emission revealed that using DMF is much more environmentally sustainable relative to that using NMP. Likewise, DMF also provides better dynamic performance by about 3 times, as indicated by the sum of integral absolute error (SIAE), when both processes are tested under ± 10% feed flowrate and ± 5% feed composition disturbances. Therefore, it is used as a base case for subsequent comparison against the retrofitted energy-intensified SSED. Relative to the base case, the proposed SSED reduces the energy consumption, TAC, and CO 2 emission by 26%, 19%, and 26%, respectively, indicating its economic and environmental advantages. It additionally provides 4 times better dynamic performance as reflected by the SIAE and it generally provides a lower transient deviation and can maintain both products at their desired purities. [ABSTRACT FROM AUTHOR]

• AEA was used to separate azeotropic mixture of ACN/EtOH/H2O via TCED process. • A superstructure TCED with four-parallel evaporator ORC system is built. • Four advantageous working fluids are selected to enhance the performance of ORC. • The intensification process shows better energy-saving and economic performance. The energy analysis and optimization of process system aiming to solve the problems of high consumption, low efficiency and unreasonable use of energy in the process of energy utilization has been widely researched and developed in recent decades. In this work, advanced exergy analysis was carried out for the triple-column extractive distillation (TCED) process separating ternary azeotropic mixture of ACN/EtOH/H2O. The total exergy destruction is 1097.69 KW. The avoidable exergy destruction, is 29.20%, mainly caused by the cooler and three condensers. Based on the thermodynamic analysis results, a superstructure TCED with four-parallel evaporator organic Rankine cycles (FPE-ORC) system is proposed, four working fluids were selected. An improved genetic algorithm is used to obtain the optimal operating parameters of the ORC system by using the exergy efficiency and annual net profit (ANP) of the ORC as two conflict objective functions. Compare with existing process, the FPE-ORC system with working fluid R600 provides the highest exergy efficiency of 12.27%, with working fluid R600a leads to the best economic benefit of 6.43 E + 4 dollar/year. [ABSTRACT FROM AUTHOR]

Acetonitrile (ACN) and Ethanol (EtOH) are important organic solvents and they are frequently used as mobile phase in high performance liquid chromatography resulting in the production of waste ternary mixture ACN/EtOH/water. The separation of such ternary systems is a key to recovery valuable solvents in waste liquid from views on economic and environmental benefits. Thus, we proposed an effective separation strategy of triple-column extractive distillation (TCED) to separate such ternary mixture with three binary azeotropes and a single ternary azeotrope for the first time. The suitable entrainer and the separation sequence were determined by thermodynamic insights (i.e., residue curve maps, isovolatility line, univolatility line and material balance lines). In addition, an improved multi-objective genetic algorithm optimization embedding the weak mutation and detection/deduplication of overlapping solutions was employed to optimize the proposed process with plenty of continuous and discrete decision variables. Finally, DMSO was determined as the most appropriate entrainer to separate such complex ternary mixture. The separation sequence of TCED process was determined as the ACN first, then EtOH and water as the last product. The optimal TCED process with the trade-off benefits between fixed capital investment and annual operating costs was obtained. • An effective TCED process is proposed to separate ACN/EtOH/water mixture. • The isovolatility and univolatility lines are used to determine best entrainer. • The separation sequence is determined via RCMs and material balance lines. • An improved MOGA is used to obtain more energy-saving TCED process. [ABSTRACT FROM AUTHOR]

• The dynamic control of the HITPED process with economic superiority is investigated. • The anti-disturbance performances of four control structures is compared by the IAE. • The CS4 with temperature-(S/F) cascade and a high selector shows gratifying effects. Recently, increasing researches have focused on the intensified heat-integrated triple-column pressure-swing extractive distillation (HITPED) owing to its superiority in economic and environmental benefits than the conventional extractive distillation. However, the dynamic controllability investigation for HITPED was lacking, resulting in the difficulties for industrial application. Therefore, separating the ternary azeotropic mixture tetrahydrofuran (THF)-methanol-water by HITPED is taken as an example to fully investigate the dynamic controllability. On the basis of the open-loop analysis a basic control structure CS1 is firstly proposed. To deal with the 20% disturbance in feed composition more effectively, the CS2 with a low selector and composition controllers is then developed. Nevertheless, composition controllers are less applied in chemical industry than temperature controllers owing to the long delay and high cost. As such, two different control structures (CS3 and CS4) without any composition controllers are then put forward. Integral absolute error (IAE) is applied to compare the dynamic performance. Under the 20% disturbances of the feed flowrate and composition, the robust control strategy CS4 with temperature controllers and a high selector exhibits the gratifying dynamic performance. The application of the selector further enlarges the dynamic researches in the distillation process. [ABSTRACT FROM AUTHOR]

• A systematic design process is proposed for the side-stream extractive distillation. • The conceptual design is conducted to determine feasible regions and sequences. • The genetic algorithm optimization is superior in evaluating multiple objectives. • The anti-disturbance performance of three control structures is compared by the IAE. • The CS3 of EDSH with feedforward and cascade shows gratifying dynamic responses. Currently, limited efforts have focused on the multi-objective optimization and effective control of the side-stream extractive distillation processes (EDS). Herein, the EDS and a heat-integration scheme (EDSH) are proposed for separating the minimum-boiling azeotropic mixture ethyl acetate (EtAC)-ethanol (EtOH). Firstly, the conceptual design by residue curve maps is demonstrated for the EDS. Following which, the genetic algorithm (GA) optimization is carried out to minimize the total capital investment cost (CAP) and the annual energy cost (ENR). Optimal scheme under the product purity constraints is then obtained from the Pareto front. And the EDSH scheme is shown with less TAC and CO2 emission. Therefore, an improved control structure CS3 combining the composition-(RR1/SIDE) cascade and feedforward strategy is developed to achieve decent dynamic responses for the EDSH. The anti-disturbance capability of different control structures in terms of the transient deviation and offsets are compared with the assistance of the integral absolute error. [ABSTRACT FROM AUTHOR]

• A systematic framework is presented for the design of a sustainable extractive distillation configuration. • The composite sustainability index is constructed considering the economic, environmental and social dimensions. • The self-adaptive mesh direct search algorithm optimization is used in evaluating the single composite objective. • The heat-pump technique can be used in extractive distillation to save energy. In order to achieve the sustainable separation design of azeotropic mixtures, this study proposed a systematic framework for distillation process optimization and intensification based on a composite sustainability index. Binary minimum azeotropic mixture ethanol-ethyl propionate was studied as an illustrative example. Specifically, three extractive distillation configurations were firstly applied on the separation and the sustainability of distillation processes were evaluated comprehensively. The composite sustainability index was constructed with the indicators of the economic, environmental, technical and social dimensions, and fuzzy weighting method was used to determine the weight of each indicator. Then, the process can be optimized with the objective of the composite sustainability index by the mesh adaptive direct search algorithm. After that, the heat-pump is further implemented to make full use of the latent heat of vapor stream in the distillation system. The T-H diagram of two upgraded processes clearly demonstrates the heat recovery while considering the specified minimum heat-transfer temperature difference. [Display omitted] [ABSTRACT FROM AUTHOR]