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Energy-saving extractive distillation for separating ethanol and 1,4-dioxane from the industrial effluent is proposed. From the point of COSMO-SAC model and thermodynamic insights, appropriate entrainer is screened. Ethylene glycol (EG) is chosen in direct extractive distillation process. Subsequently, it is observed that increasing the pressure can make the azeotropic point of ethanol and 1,4-dioxane disappear. Thus, both EG and dimethyl sulfoxide (DMSO) are used as entrainers in indirect extractive distillation (IED) process. The entropy generation of different sections of each column is analyzed. And then, heat integration and heat pump technologies are used to reduce more energy consumption. The comparison results show that the total annual cost (TAC), total energy consumption, CO 2 emissions and entropy generation of IED process with DMSO as entrainer (IED-DMSO) is smaller than those processes with EG as entrainer. The IED-DMSO process in combination with heat integration performs best, the TAC is reduced by 41.96%, energy consumption is reduced by 50.28%, CO 2 emissions is decreased by 50.28% and entropy generation is decreased by 57.46% comparison with the IED-EG process. [ABSTRACT FROM AUTHOR]

• Reaction distillation processes to separate ethanol/1,4-dioxane/water mixture. • MOGA optimize with economy and entropy generation as the objective functions. • Novel side-stream reactive-extractive distillation process with intermediate reboiler. • Performance comparison with existing extractive distillation process. Conventional distillation methods cannot separate ternary mixtures containing multiple azeotropes. This article designs two reaction distillation processes to recovery ethanol and 1,4-dioxane from wastewater, and a novel side-stream reactive-extractive distillation process with intermediate reboiler (SREDIR) process for the first time is proposed to separate this mixture. Taking economy and entropy generation as objective functions, multi-objective genetic algorithm is used to optimize the processes. It is concluded that all the proposed reaction distillation processes are energy-saving than the existing extractive distillation process for recoverying ethanol and 1,4-dioxane from wastewater. This existing process is an indirect extractive distillation process with DMSO as entrainer with heat integration (IED-DMSO-HI) process. Compared with IED-DMSO-HI process, the SREDIR process is economic since its total annual cost is reduced by 64.30%. However, the total entropy generation of SREDIR process is increased by 16.06%. Therefore, if there are high thermodynamic requirements for the separation process, reactive distillation requires careful consideration. [ABSTRACT FROM AUTHOR]

BACKGROUND: Biobutanol is considered to be a promising alternative biofuel in terms of sustainability and environmental friendliness because of its desirable properties. High purity isopropanol–butanol–ethanol (IBE) mixture can be directly used as gasoline additive. However, the purification process of IBE is hindered because of its low concentration and high energy consumption. In order to reduce energy consumption and improve the efficiency of the IBE purification process, two novel processes combining liquid–liquid extraction with extractive distillation or azeotropic distillation are proposed. Moreover, the heat integration designs of the processes are carried out to further reduce energy. These processes are compared with regard to energy, economic, environmental and exergy impact. RESULTS: The results show that the energy consumption of these enhanced processes are effectively reduced compared with the original process in the literature. Among them, the thermal integrated process of liquid–liquid extraction combined with extractive distillation is the best design, which has a total annual cost of $32.656 × 105 and an energy consumption of 5936.94 kW. CONCLUSION: Compared with the original process, this process can save 71.33% of energy consumption. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

An investigation and comparative analysis on the design and control of the maximum-boiling ethylenediamine (EDA) dehydration system is made in this work. Extractive distillation (ED) and heterogeneous azeotropic distillation (HAD) are used to separate EDA/water mixture that forms a maximum-boiling homogeneous azeotrope. 1,4-butanediol (BDO) and n -propyl acetate (NPAC) are selected as the suitable heavy/light entrainer from three candidate ones for each distillation process respectively. Savings of 17.80% in energy consumption and reduction of 26.26% in minimal total annual cost (TAC) can be obtained by comparing optimum design of ED process to that of HAD process for this system. Moreover, an initial control structure (CS) and an improved one are established for each distillation process. Finally, the comparison of dynamic responses indicates that the HAD process represents an alternative at the stand point of dynamic control for this system. [ABSTRACT FROM AUTHOR]

Benzeneand cyclohexane (CYH) can be separated via extractive distillationusing sulfolane (SULF) as entrainer. In this Article, the steady stateof an extractive distillation system has been simulated using theRadFrac model in Aspen plus, and the controllability of this systemwith feed flow rate and feed composition disturbances has been studiedin Aspen Dynamics. Sensitivity analysis is used to obtain optimaloperation conditions. The common control scheme for extractive distillationis infeasible. Two control structures are demonstrated in this Article.Each control structure has three main temperature controllers, twoin the extractive distillation column and one in entrainer recoverycolumn. Although both control structures can solve all disturbanceissues and maintain the product purities very close to the set points,the dynamic responses of initial control structure have large transientdeviation when +20% feed flow rate disturbance is introduced, whilethe improved control structure can overcome this obstacle. [ABSTRACT FROM AUTHOR]

• Three novel extractive distillation processes are designed. • The remixing effect and entropy production of processes are investigated. • Entropy production is used as an objective of multi-objective optimization. • Intermediate reboiler can reduce the energy requirement for high-pressure steam. • Heat integration can be applied due to the presence of intermediate reboiler. Side-stream extractive distillation is extensively employed to separate azeotropic mixtures since its energy-efficient benefits. Nevertheless, its economic effect is not always obvious due to the introduction of expensive high-pressure steam. In this article, a conventional triple-column extractive distillation process is firstly researched for separating n-hexane/ethyl acetate/acetonitrile mixture. To effectively decrease the requirement for high-pressure steam and achieve a reduction in economic costs of side-stream extractive distillation, three innovative side-stream extractive distillation processes with intermediate reboiler are proposed. A multi-objective genetic method is applied to optimize the four processes with total annual cost (TAC) and entropy production as two objective functions. Additionally, due to the presence of intermediate reboiler, heat integration design is implemented to the three side-stream extractive distillation processes with intermediate reboiler. Compared to the triple-column extractive distillation process, the heat integration of the three side-stream extractive distillation processes with intermediate reboiler exhibit better performance considering economy, energy-efficient, and entropy production. It indicates that the heat integration of the double side-stream extractive distillation process with intermediate reboiler can reduce 20.10% of TAC, 29.65% of energy consumption, and 35.63% of entropy production, respectively. [ABSTRACT FROM AUTHOR]

• The conventional extractive distillation process for separating acetonitrile/isopropanol/water mixture. • The intensification processes combined with heat-integrated and intermediate reboilers are proposed. • The energy, exergy, economic and environment analysis of process is implemented. • The best energy-efficient process presents great economic and environment performance compared with other processes. A conventional triple-column extractive distillation is researched for the separation of acetonitrile/isopropanol/water mixture with ethylene glycol (EG) as entrainer. In this article, the pressure-relative volatility curve is investigated to find the suitable pressure of column. To achieve the further energy saving, three heat-integrated schemes and two heat-integrated combined with intermediate reboilers schemes are researched based on the conventional extractive distillation. Both two heat integration with intermediate reboilers schemes shown the better performance than other schemes since the further analysis of the energy, exergy, economic and environment (4E) were investigated. For the most energy saving design, PHI-IHI2, it has 48.50% energy-saving, 70.73% exergy efficiency enhanced, 36.24% reduction in total annual cost (TAC) and 48.55% reduction in gas emissions with the comparison of the conventional extractive distillation (CED) process. The result shows the extractive distillation combined with heat-integrated and intermediate reboilers presented great energy-efficient, economy saving and environment friendly for separating acetonitrile/isopropanol/water mixture. [ABSTRACT FROM AUTHOR]

• A novel 6-column distillation process is proposed for isopropanol-butanol-ethanol purification. • The high-purity isopropanol-ethanol mixture is obtained by extractive distillation as a gasoline additive. • Double-effect distillation and heat-pump assisted distillation are applied in 6-column distillation process. • The intensification process using heat-pump assisted distillation performs best in energy, economy and environment. Biofuels from biomass have attracted great attention due to the increasingly serious environmental problems and the increasing demand for fossil fuels. Butanol is considered as a promising alternative biofuel because of its favorable properties, and it can be produced by IBE fermentation broths. Moreover, the high-purity isopropanol-ethanol (IE) mixture produced by IBE fermentation can be used as a gasoline additive. However, the IBE purification process is hindered by its low concentration and energy-intensive separation from IBE fermentation broths. In this work, a novel 6-column distillation process for IBE purification is proposed to reduce the total energy consumption (TEC) and capital cost. Furthermore, for achieving further energy savings, the double-effect distillation (DED) and heat pump assisted distillation (HPAD) technologies are used as the process intensification methods. These processes are compared in terms of energy, economic and environmental impact. The results indicate that the total annual cost (TAC), TEC and gas emissions of the IBE purification process can be reduced effectively by the three intensification processes, among them, the process intensification with HPAD (PI-HPAD) process is the best one, which can achieve 46.72%, 26.96% and 30.52% savings of TEC, TAC and CO 2 emission, respectively. [ABSTRACT FROM AUTHOR]

• Three side-stream extractive distillation processes are proposed to separate n-hexane/ethyl acetate/acetonitrile mixture. • Multi-objective optimization is performed with TAC and entropy production as objective functions. • Side-stream extractive distillation processes can reduce energy consumption. • The optimal side-stream extractive distillation process is identified. In this study, a conventional triple-column extractive distillation process and three side-stream extractive distillation processes are investigated for separating a ternary mixture of n-hexane/ethyl acetate/acetonitrile. A multi-objective genetic optimization method is applied to optimize the four processes with the minimum total annual cost (TAC) and entropy production as two objective functions. The results indicate that the three side-stream extractive distillation processes can effectively reduce the remixing phenomenon, achieving a reduction in energy consumption. In addition, the three side-stream extractive distillation processes exhibit better economic advantages and significantly decrease entropy production compared to the conventional triple-column extractive distillation process. Among the processes, the single side-stream extractive distillation process presents the optimal performance considering economy, energy-efficient and entropy production. Specifically, it can reduce 6.17% of TAC, 7.85% of energy consumption and 15.54% of entropy production in comparison to the conventional triple-column extractive distillation process, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Two energy efficient extractive distillation processes are proposed to separate acetonitrile/1,4-dioxane/water mixture in this study. The COSMO-SAC model is chosen to screen suitable entrainer and dimethyl sulfoxide is selected. Process intensification technologies of heat pumps and heat integration are utilized in the processes for energy conservation. Several evaluation methods containing energy, economic, environmental and exergetic analysis are introduced to evaluate the performance of different processes. The most energy-saving and environmental friendly process is heat pump assisted direct extractive distillation that achieves an energy reduction by 53.58% and a carbon dioxide emission reduction by 53.56% compared to the indirect scheme, while the direct scheme assisted with heat integration performs best that achieves a reduction by 40.38% on total annual cost. [ABSTRACT FROM AUTHOR]

• Extractive distillation is proposed to separate IPA/Dioxane /water mixtures. • Multi-objective optimization with TAC and entropy generation are the objective functions. • DWC and HI technologies are used to decrease the irreversibility of the processes. • DWC technology is not ideal but heat integration technology performs best. Several extractive distillation processes with DMSO as extractant are proposed to separate isopropanol/1,4-dioxane/water azeotropic mixtures in this study, including direct extractive distillation (DED), indirect extractive distillation (IED), DED process with dividing wall column (DED-DWC), IED process with dividing wall column (IED-DWC) and IED process with heat integration (IED-HI). The multi-objective genetic algorithm employs total annual cost (TAC) and entropy generation as the objective functions to optimize processes. The TOPSIS entropy weight method has invested to identify the appropriate optimal solution. DWC and heat integration technologies are proposed to decrease the irreversibility of DED and IED processes. The results showed that the best option to perform the separation of the mixture was the IED-HI process. It is gratifying to note that the TAC and entropy generation of IED-HI process is decreased by 15.36 % and 28.84 %, respectively, in relation to the IED process. [Display omitted] [ABSTRACT FROM AUTHOR]

• A basic four-column extractive distillation process with dehydration column to separate azeotrope of acetonitrile/1,4-dioxane/water. • An innovative extractive distillation process with an integrated column for separating acetonitrile/1,4-dioxane/water. • Using the SAA to optimize basic process. • Introduce heat integration and heat pump technology on the basis of basic and innovative processes. Acetonitrile and 1,4-dioxane are significant organic compounds, which are widely used in many chemical production processes. However, some pharmaceutical or chemical factories discharge large amounts of organic wastewater containing acetonitrile and 1,4-dioxane. For dealing with this special multi-azeotrope system, it is necessary to design a dehydration extractive distillation separation scheme. Thus, an extractive distillation process with dehydration column (BFED) and an innovative extractive distillation process with an integrated column (CTED) which can function as dehydration column and extractant recovery column were proposed. For the sake of reducing energy consumption, three improved processes with direct steam injection, heat integration and heat pump were exploited. The proposed processes are comprehensively evaluated by total energy consumption and economic demand, CO 2 emissions and exergy analysis. As a result, the heat pump assisted CTED process can reduce 26.86% of the total annual cost, 40.61% of energy consumption, 40.71% of CO 2 emission and 44.82% of exergy destruction, respectively, compared with the BFED process. [ABSTRACT FROM AUTHOR]

For the purpose of recycling resource and cleaner production, the extractive distillation schemes with different ionic liquids as extractants are proposed to separate ethyl acetate and methanol. In fact, the evaluation of extractants should not just focus on the separation effect, the effectiveness for the recovery of extractants which has a great influence on the overall benefits of extractive distillation process also need to be paid more attention, especially for the ionic liquids (ILs). On the basis of the VLE diagram, σ-Profiles, and interaction energy based on molecular dynamics, the separation effects of the selected extractant are following the order of 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) > 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]) > dimethyl sulfoxide (DMSO). However, the decomposition temperature of [EMIM][DEP] is much higher than that of [EMIM][OAc], which leads to the better effectiveness for extractant recovery. Then, several recovery configurations are explored owing to different decomposition temperature of selected ILs. The result shows that the heat integration assisted the process with [EMIM][DEP] as extractant which utilizes two-stage evaporators extractant recovery configuration has a better performance than other processes and can reduce 35.07% of TAC, 37.59% of energy consumption and 37.36% of gas emission compared with conventional extractive distillation process with DMSO as extractant [ABSTRACT FROM AUTHOR]

• An innovative extractive distillation process combining prefractionator with extractive distillation column for separating high-concentration azeotropic mixtures. • Multi-objective optimization is conducted with the minimization of TAC, CO 2 emissions, and entropy generation as the objective functions. • Entropy generation analyses highlights areas of irreversibility. • Heat pump technology and heat integration technology have obvious energy-saving effects. The process design and optimization of separating azeotropic mixtures by extractive distillation (ED) has been a hot problem in recent years. Conventional ED process often faces challenges of high energy consumption and high costs when dealing with azeotropic mixtures containing a high content of a certain component. Therefore, an energy-efficient innovative three-column extractive distillation process (ITCED) that is capable of simultaneously performing preconcentration and extractive distillation functions within a complex distillation column for separating ethyl acetate/n-propanol/water azeotropic mixture containing a large amount of n-propanol is developed. Multi-objective optimization is conducted with the minimization of total annual cost (TAC), CO 2 emissions, and entropy generation as the objective functions. According to the optimization results, the ITCED process exhibits substantial advantages compared to the conventional three-column extractive distillation process (TCED), with reductions of 34.95% in TAC, 35.84% in CO 2 emissions, and 38.91% in entropy generation. Subsequently, heat pump and heat integration technologies are employed to enhance the ITCED process for the further energy conservation. As a result, compared with the TCED process, the DHP-HI-ITCED process achieves savings of 48.18% in TAC, 67.5% in CO 2 emissions and 72.96% in entropy generation. [ABSTRACT FROM AUTHOR]

• A four-column extractive distillation process with preconcentration distillation column to separate ethyl acetate, isopropanol and water azeotropic mixtures. • A three-column process combining the preconcentrated column with the extractant recovery column for separating ethyl acetate, isopropanol and water. • Using the SAA to optimize basic process. • The four-column and three-column extractive distillation processes combine with heat integration and heat pump. Ethyl acetate (EAC) and isopropanol (IPOH) are important organic chemical raw materials. During the production of ampicillin sodium, there are a large amount of waste water containing EAC and IPOH. In order to separate the dilute solution containing EAC, IPOH, both a four-column extractive distillation process with preconcentration distillation column (PDC) and a three-column extractive distillation process of combining the preconcentrated column with the extractant recovery column (ERC) are presented. In addition, three intensified processes with the application of heat integration and heat pump are proposed. The feasibility of the proposed processes is evaluated from four aspect: economy, energy consumption, environment, exergy analysis. The results show that these five processes have a good effect of energy saving and cost saving. Especially, the vapor recompressed heat pump assisted CTE process (HP-CTE) process, which is the most energy saving scheme, can reduce 37.80% of total annual cost, 55.43% of energy consumption, 54.46% of CO 2 emission, 54.85% of SO 2 emission, 54.82% of NO X emission, and 53.17% of exergy destruction, respectively, compared with the proposed four-column process. [ABSTRACT FROM AUTHOR]

Conventional extractive distillation processes have been proposed to separate the ternary ethyl acetate-1,4-dioxane-water system with azeotropes. Energy-efficient extractive thermally coupled processes with heat integration have been developed to reduce energy consumption. A macro-analysis of the energy, exergy, economy, and environment is conducted to estimate the economic and environmental benefits. The results proved that an extractive dividing-wall column with a heat-integrated process possessed the greatest energy-saving potential, delivered best economic performance and exhibited highest exergy efficiency. Compared to those of a conventional direct extractive distillation process, the total energy requirement and total annual investment cost are reduced by 28.18% and 24.28%, respectively, by the best energy-saving process. The total exergy efficiency of it is 1.779%. The proposed cleaner and sustainable extractive dividing-wall column configuration could achieve energy saving, investment reduction, and effectively enhance the exergy efficiency. • The extractive distillation is used for ethyl acetate-1,4-dioxane-water separation. • The solvent is screened using the COSMO-SAC model. • Five processes are comprehensively evaluated from energy, economy and environment. • The thermally coupled configuration exhibited best benefits. [ABSTRACT FROM AUTHOR]

• Two schemes of energy efficient extractive distillation for separation of azeotropes. • Vapor recompression combined with heat integration for process intensification. • Application of preheater and auxiliary reboiler under different conditions in the heat pump process. • Economic, energetic, environmental and exergy evaluation for proposed processes. This study is focused on the separation for the ternary mixture of isopropanol/tetrahydrofuran/water with extractive distillation method, including indirect extractive distillation and direct extractive distillation. Dimethyl sulfoxide is selected to be the optimal solvent in the separation process through COSMO-SAC model and relative volatility. The vapor recompressed heat pump technology and heat integration are introduced for further energy saving. The energetic, economic, environment and exergy evaluation are utilized to estimate the performance of the proposed processes. The direct extractive distillation tends to be better than indirect extractive distillation. The double-heat pump assisted direct extractive distillation with heat integration shows the best performance in energy conservation and reducing cost, which achieve a reduction on energy consumption and total cost by 64.97% and 34.26% respectively compared to the direct extractive distillation process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The sustainable process of reactive extractive distillation for treatment wastewater is proposed. • The intensified configuration applied in processes are developed. • The calculation of σ-Profiles used for screening the entrainer. • Comparisons from economic and environmental for assessment the benefits of proposed processes. • The intensified process with heat-integrated and intermediate reboiler presents best economy and environmental-benefits. Large amount of high purity acetonitrile and isopropanol are required as the raw material to meet the growth requirements of rapidly the chemical industries development. The high demands for acetonitrile and isopropanol have created the need for an efficient sustainable process to reduce the energy consumption which satisfies the environment regulations. Thus, a sustainable process of reactive coupling extractive distillation to separate acetonitrile/isopropanol/water ternary mixture is proposed. The intensified processes of heat-integrated combination intermediate reboiler are explored to further reducing energy consumption. The comparisons from the views of 4E which contains energy, exergy, economic and environment are conducted to assessment proposed processes benefits. The advanced intensification process of reactive extractive distillation (RED-HI-IR) has the best energy saving potential and economic benefits which achieves the reductions on energy, total annual cost and gas emissions of approximately 54.16%, 39.02% and 54.16% respectively, and the total exergy efficiency is up to 97.52%. Thus, heat-integrated and intermediate reboiler technology used of distillation is of significance for the sustainable chemical process development. [ABSTRACT FROM AUTHOR]