Conventional Extractive Distillation Research Articles

Mechanism analysis and performance evaluation of clean and efficient recovery of N-heptanol/N-hexanol from wastewater via extractive distillation with green mixed entrainer

A clean and sustainable process for separating n-heptanol/n-hexanol/water industrial mixing system by extractive distillation via mixing organic solvent with ionic liquid as an entrainer was proposed. The mechanism of intermolecular microscopic interaction was explored by quantum chemistry calculation. By using multi-objective optimization, the optimal operating parameters of the process were obtained. In addition, process intensification technology was introduced, which improved the problems of high cost and high energy consumption in the conventional extractive distillation process. Finally, multiple performances were evaluated and analyzed for different processes. It was found that the coupled heat integration and heat pump technology to assist the extractive distillation process saved 10.45% in terms of economy, reduced gas emissions by 49.00%, and reduced energy consumption by 48.99% compared to the basic extractive distillation process. This confirmed the reliability and feasibility of implementing the process intensification technology. This work demonstrates the application of organic solvent mixed with ionic liquid as entrainer and process intensification technology in the extractive distillation process, providing guidance and reference for the design of the extractive distillation process.

Novel energy-efficient design of side-stream extractive distillation process with intermediate reboiler for separating multi-azeotropic mixture based on multi-objective optimization

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.

Investigation of side-stream extractive distillation for separating multi-azeotropes mixture based on multi-objective optimization

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.

Applicability exploration and sustainable assessment of heat integration and vapor recompression heat pump to side-stream extractive distillation processes for separating ternary azeotropic system

The side-stream extractive distillation (SSED) process is attracting extensive attention due to its high energy efficiency for separating ternary azeotropic mixture. However, the correlation between the bottom temperature level of distillation columns depending on the flowrates and compositions of side streams and the introduction of heat integration (HI) and vapor recompression heat pump (VRHP) technology is ignored. In the work, a range of initialization extractive distillation processes including one conventional extractive distillation (CED) process and five SSED processes considering different flowrates, compositions, and feed locations of side streams are proposed for separating acetonitrile/isopropanol/water ternary azeotropic system. The optimization results with the minimum the total annual costs (TAC) as the optimization objective show that not all SSED schemes are superior to the CED separation process, and the SSED separation schemes can achieve up to a 2.72 % reduction in the TAC. Following that, the HI and VRHP assisted extractive distillation schemes are proposed based on the temperature levels between the top and bottom of different distillation columns and compressor restraints for the initialization extractive distillation schemes mentioned after optimization. Moreover, sustainable evaluations covering economy, energy consumption, environment, and energy utilization are implemented for the extractive distillation schemes proposed. The evaluation results indicate that the CED-HI scheme overcomes all SSED-HI and SSED-VRHP schemes in terms of economic costs, but the optimal SSED-HI processes can reduce 8.77 % of energy consumption and 4.73 % of CO2 emissions, while the energy utilization raised from 1.70 % to 1.78 % compared to the CED-HI process.

A novel reactive-extractive distillation process for separation of water/methanol/tetrahydrofuran mixtures

The design of separation systems for the purification of azeotropic mixtures is of great importance in the chemical industries from economic and environmental points of view. Two novel reactive-extractive distillation (RED) processes, new design (I) and new design (II), were proposed for separating the azeotropic mixture of water/methanol/tetrahydrofuran (THF). These processes were compared to a conventional extractive distillation (ED) process. New design (I) employs dimethyl sulfoxide as a solvent, while new design (II) utilizes ethylene glycol. Ethylene oxide was introduced to the first column in both designs, enabling the in-situ production of ethylene glycol, a valuable byproduct. This is a novel solution to separate water from the azeotropic mixture by reaction between ethylene oxide and water. Aspen Plus software was used to simulate and design the processes. Both suggested designs were compared economically with the base design which is an ED process. According to the results, the new design (I) is more cost-effective and environmentally friendly alternative to the base design and the new design (II). It has a lower total capital cost and produces less carbon dioxide. Additionally, it generates a valuable by-product, ethylene glycol, which can be sold for substantial revenue. As a result, the new design (I) is the preferred choice for replacing the conventional extractive distillation method.

Efficient purification of n-butanol by thermally coupled extractive distillation with mixed entrainer

To solve the problems of difficult separation of azeotropes and high energy consumption in the preparation of n-butanol from the fermented mother liquor, this study focused on the separation process integration of water/acetone/ethanol/n-butanol mixture based on the combination of mixed entrainer and thermally coupled distillation technology. Based on quantum chemical calculations, the molecular polarity and weak interaction between the entrainer and the mixture to be separated were studied at the molecular scale, and the separation mechanism of extractive distillation was revealed. Based on the simulation results, the three different configurations' process performance was evaluated and compared to the benchmark conventional extractive distillation process with ethylene glycol as the entrainer. The thermally coupled extractive distillation process with mixed entrainers can reduce the total annual cost by about 39.87%, reduce energy consumption and acid gas emissions by 46.53%, and improve the thermodynamic efficiency by 47.57%. The thermally coupled extractive distillation process with mixed entrainers is an economical, energy-saving, and environmentally friendly production scheme superior to the conventional extractive distillation process. The thermally coupled extractive distillation process, as an essential energy-saving technology for producing n-butanol from fermentation mother liquor, has broad development prospects.

Exploration of different water content on the performance of reactive-extractive distillation for separating the ternary azeotropic mixture

Reactive-extractive distillation (RED) has gained significant attention as an innovative approach for separating azeotropic mixtures. Although many studies have reported its positive benefits, no studies have explored the impact of varying water content on RED performance, a domain that has seen exhaustive exploration in conventional extractive distillation. In this study, we investigate how water content affects RED performance using the separation of ethyl acetate (EA), 1,4-dioxane (DIO), and water as a case study. We design diverse configurations tailored for feed compositions ranging from 0.35 to 0.8 water mole fractions using a double column reactive-extractive distillation (DCRED). These configurations are globally optimized and the performance is compared against the triple-column conventional extractive distillation (TCCED) based on economic, environmental, and thermodynamic efficiency considerations. The TAC and CO2 emission of TCCED schemes exhibit the linear decreases, reaching its lowest point at 50 mol.% water content. Beyond this threshold, both indicators increase significantly, even surpassing the reference case (20 mol.% water) at 80 mol.% water content. The thermodynamic efficiency of TCCED behaves inversely due to the intrinsic exergy destructions. Interestingly, the DCRED schemes show almost linear decreases in the trends of both economic and environmental indicators, and the notable deviations are then observed at 65 mol.% water content, accompanied with a slight decrease up to 80 mol.%. The thermodynamic efficiency of DCRED scheme gives an inverse trend, identical to those observed in TCRED. Overall, TCCED performs best at 50 mol.%, in which DCRED excels at 80 mol.% water content. This comprehensive study bridges a significant knowledge gap, offering insights into optimizing RED processes for varying water content, an unexplored topic despite widespread application of RED.

Design and 4E analysis of heat pump-assisted extractive distillation processes with preconcentration for recovering ethyl-acetate and ethanol from wastewater

The separation of ternary azeotropes with a high content of one component using extractive distillation is energy intensive, and the introduction of preconcentration can significantly improve process economy. In this paper, the conventional three-column extractive distillation (TCED), four-column extractive distillation (FCED) with preconcentration, and three-column extractive distillation with integrated distillation column (TCED-IDC) are established and economically optimized to minimize the total annual cost (TAC) for recovering ethyl-acetate (EAc) and ethanol (EtOH) from wastewater containing a large amount of water. The preconcentration and solvent recovery functions can be integrated in IDC. Following that, the vapor recompression heat pump (VRHP) is introduced to further reduce energy consumption for the TCED-IDC process. The two VRHP-TCED-IDC processes are correspondingly designed. Simultaneously, the processes proposed are evaluated in terms of economy, energy consumption, environment and exergy destruction (4E analysis). The environmental analysis is performed via calculating Global Warming Potential (GWP) index using Life Cycle Assessment method. The two VRHP-TCED-IDC processes demonstrate superior performances with regard to 4E analysis. The most efficient VRHP-TCED-IDC process reduce over 32.0 %/16.0 %/6.8 % of TAC, 53.4 %/42.4 %/33.7 % of energy consumption, 62.0 %/53.0 %/45.9 % of GWP, and 49.7 %/35.7 %/29.3 % of exergy destruction compared to the TCED/FCED/TCED-IDC processes, respectively.

Separation of a two binary-azeotrope acetonitrile-cyclohexane-toluene ternary mixture via continuous triple column extractive distillation with heat integration: design, simulation, and multi-objective genetic-algorithm (MOGA) optimization

ABSTRACT Using a sustainable method for separating azeotropic mixtures, such as extractive distillation, is crucial for environmental and resource sustainability. Cyclohexane, acetonitrile, and toluene are essential solvents in different chemical processes. This ternary mixture has two binary azeotropes between cyclohexane-acetonitrile and acetonitrile-toluene at atmospheric pressures. Using residue curve maps and a uni-volatility line, n-butylbenzene was selected as a viable entrainer for extractive distillation, among other possibilities. Unlike conventional designs, the recycled entrainer was only sent to the first column in this simulation. The wasted energy from the recycled entrainer was used to supply reboilers duty through integration. A 3-D material balance was performed to understand the separation procedures better. High-purity acetonitrile, cyclohexane, and toluene will also be obtained from the first, second, and third columns. Finally, a multi-objective genetic algorithm with 14 key decision variables was utilized to reduce total annual cost (TAC) and CO2 emissions and improve thermodynamic efficiency as objective functions from economic, environmental, and energy efficiency perspectives. Optimized results reveal that a heat-integrated design reduces almost 25% TAC and 46% CO2 emissions compared to conventional extractive distillation and does not significantly affect thermodynamic efficiency. This research could be valuable for separating azeotrope systems from other ternary mixtures.

Design and multiple performance evaluation of green energy saving process for ethyl acetate/ethanol/water azeotrope separation by extractive distillation based on mixed solvent

The clean and efficient separation of ethyl acetate/ethanol/water azeotrope is of great significance for the production of high-purity ethyl acetate. In this study, a highly efficient separation of ethyl acetate/ethanol/water azeotrope by extractive distillation based on mixed solvent was developed. The relative volatility and quantum chemistry calculation were used to determine the alternative entrainer of mixed solvent. The multi-objective optimization based on genetic algorithm was carried out to obtain the optimal process scheme which considered both economy and environment. Three energy-saving process schemes were developed based on the conventional extractive distillation process, and the economic, environmental, energy and exergy properties of each process were investigated. The results show that the heat pump-assisted extractive distillation process may yield a significant reduction in gas emission and process energy consumption, showing an obvious advantage over the conventional extractive distillation process and the process proposed by previous researchers. The results of this study have important significance for the separation of high purity ethyl acetate and the recovery of wastewater containing ethyl acetate and ethanol. The research approach can be applied to further systems and serve as a reference for the creation of extractive distillation with mixed solvent.

Economic and Environmental Assessment of a Novel Integrated Three-Column Extractive Distillation Process for Recycling Organics from Wastewater

For diluted wastewater with azeotropes discharged from chemical plants, it is important to design a sustainable extractive distillation process to achieve efficient separation. By separating the dilute wastewater containing isopropanol and acetonitrile, it is proved that the four-column extractive distillation processes with a preconcentration column and a novel three-column process containing an integrated column with preconcentration and solvent recovery function can achieve energy conservation and cost reduction. At the same time, heat integration and heat pump-assisted technologies were further used to intensify the proposed processes. The proposed processes are evaluated in terms of economy, energy consumption, and CO2 emissions. The results display that the double heat pump-assisted extractive distillation process can obtain 75.10% energy saving and the heat integration of the extractive distillation process with a preheater can save 69.45% cost, compared with the conventional extractive distillation process.

Analyzing the sustainability of intensified side‐stream extractive distillation for binary azeotropic separation: a comparative study

AbstractBACKGROUNDThe 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.RESULTSWe 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.CONCLUSIONAltogether, designing the intensified process via process optimization does not always guarantee significant improvement in all sustainability indicators. © 2023 Society of Chemical Industry (SCI).

New single-column extractive distillation with heavy entrainer to separate binary azeotropic mixtures

Extractive distillation with heavy entrainer is widely used in the separation of binary azeotropic mixtures. While a large amount of energy is always consumed in conventional two-column processes. A new flash tank-assisted single-column extractive distillation with heavy entrainer (FT-SCED) is proposed in this paper. The side vapor-phase stream with high heavy component content is withdrawn from the extractive column, and then it is partly condensed in a flash tank. By this means, the high-purity light and heavy products can be achieved from the overheads of column and flash tank, respectively. To obtain the proposed process, an initial single column extractive distillation with heavy entrainer is designed firstly. Then the flash tank is added into the process on the basis of the thermodynamic feasibility analysis. Genetic Algorithm procedure is employed to optimize the independent variables of the obtained process. Two case studies show that the proposed process has lower annual total cost compared with conventional extractive distillation and extractive dividing wall column. PI control strategies are established for the proposed processes in two cases. The dynamic control results show that these control strategies handle feed flowrate and composition disturbances excellently.

Data-driven surrogate optimized and intensified extractive distillation process for clean separation of isopropanol from water: A sustainable alternative

Isopropanol (IPA) is an important chemical because of its wide use in chemical and related process industries. In the production of IPA, an important processing step is its recovery and purification. The objective of this paper is to analyze different processes to find an energy efficient and environmentally friendly alternative for clean separation of isopropanol from water. A six-step design methodology is employed, which starts with the conventional extractive distillation process (EDP). Design parameters of EDP are first optimized by using a proposed artificial neural network (ANN) based data-driven surrogate (ANNDS). Using the optimal EDP as a reference design, improvements (intensification and/or integration) are considered through the so-called distillation-membrane hybrid process (DMHP), by heat pump vapor recompression (HP-EDP-I and HP-EDP-II), and dividing wall column without (E-DWC) and with (HP-E-DWC) heat pump, respectively. The results show that DMHP can be considered as a retrofit option with an energy reduction of 2.45% for the whole EDP. As compared to EDP, energy consumed in HP-EDP-I, HP-EDP-II, E-DWC, and HP-E-DWC can be reduced by 37.7%, 44.1%, 40.0%, and 56.4%, respectively. Moreover, CO2 emission is reduced by 42.6%, 50.4%, 40.0%, and 59.0%, respectively. Therefore, HP-E-DWC process is found to be the most sustainable alternative for the clean separation of isopropanol from water among the proposed processes. With further consideration of economic performance, HP-E-DWC is found to have the best performance with high separation capacity (>37500 kg/h), while E-DWC is found to be a favorable choice for a small plant with low capital cost and intermediate environmental impacts.

Towards sustainable separation and recovery of dichloromethane and methanol azeotropic mixture through process design, control, and intensification

AbstractBackgroundHere 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.ResultsThe 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.ConclusionAmong 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).

Evaluation on the separation effect and extractant recovery efficiency of extractive distillation for separating ethyl acetate/methanol with ionic liquids as extractants

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

Comparison of different extractive distillation processes for chloroform/n‐hexane separation: design and control

AbstractBackgroundWhen extracting total glycosides from Panax notoginseng, a waste liquid containing chloroform and n‐hexane will be produced. These waste liquids are not separated and recycled in time, which will not only waste resources but also cause environmental pollution. Chloroform and n‐hexane form an azeotrope which cannot be separated by ordinary distillation methods. This study proposes three extractive distillation processes to separate the chloroform/n‐hexane azeotrope: conventional extractive distillation (ED), side‐stream extractive distillation (SSED) and extractive dividing wall column (EDWC). The total annual cost (TAC) and carbon dioxide (CO2) emissions of the three options were compared, and the optimal process was selected. Furthermore, this research developed dynamic control of the optimal process.ResultsCompared with ED, from the perspective of economic indicators, the SSED process showed 18.9% reduction in TAC yet the EDWC process showed 33.2% reduction in TAC. In terms of CO2 emission indicators, the EDWC process also is more advantageous. Three control structures thus were developed for EDWC: applying ±5% or ±10% feed flow disturbance, and feed composition disturbance. The results show that CS3 with temperature composition cascade control structure can perfectly control all disturbances.ConclusionThis paper designs an economical, environmentally friendly and controllable chloroform/n‐hexane azeotropic separation process, which can provide a reference for the industrial application of chloroform/n‐hexane separation. © 2022 Society of Chemical Industry (SCI).

Are process-intensified extractive distillation always energetically more efficient?

The thermally coupled, dividing wall column, and side-stream configurations are some of the energy-intensified techniques widely applied to the extractive distillation for improving the energy efficiency. Today, several heuristics are available for analysing the energy-saving efficiency of these intensified techniques for ideal distillation system but there is no heuristic available for analysing the complex distillations system. Therefore, it has not yet been established what variables affect the energy-savings and under what particular conditions the intensified processes for these complex distillation systems present energy-savings. In this work, we aim to provide insights and preliminary conclusions that open a field of study for a more detailed and in-depth analysis for future researches through three different case studies where their corresponding intensified configurations do not provide any energy-saving relative to the conventional extractive distillation (CED). Based on our preliminary analysis, we attributed this to the poor values of interconnecting flowrate or composition and high column internal vapour flowrate. Our results also revealed the possibility of extending several heuristics, previously developed for evaluating the energy-saving efficiency in ideal distillation system, for complex distillation. Lastly, several recommendations are given that were derived from our simulation results and the analyses we carried out on existing publications.

Economic, environmental, and exergy analysis of an efficient separation process for recovering low-carbon alcohol from wastewater

Extractive distillation separation is a continuous and effective process for the separation of industrial wastewater components. In this study, a method to recover high-purity ethanol and isopropanol from industrial wastewater via extractive distillation has been proposed. Three enhanced energy-saving processes were developed to reduce the economic costs and environmental impact of distillation processes. The process operation parameters with the best economic performance were obtained based on a sequential iterative optimization method with the total annual cost as the objective function. Results show that, thermally coupled technology can effectively reduce the economic cost. Compared with the conventional extractive distillation process, the total annual cost of the thermally coupled extractive distillation process was the lowest, accounting to a reduction of 33.14%. The heat recovery rate of the heat pump-assisted thermally coupled extractive distillation process was the highest (1979 kW), and the total energy consumption was the lowest (5762.4 kW). The gas emission (2432.72 kg/Y), GWP (1246.42 kg CO2-Eq), AP (2.23 kg SO2-Eq), HTP inf (38.66 kg DCB-Eq), Eco tox (20.04 CTUe), and exergy loss (20.73%) of the heat pump-assisted thermally coupled extractive distillation process were the lowest. This work has important guiding significance for the efficient recovery of low-carbon alcohols from industrial wastewater and promoting cleaner production in the chemical industry.

Comparative optimal design and effective control of different pressure extractive distillation for separating acetone - Methanol

Acetone and methanol are critical industrial feedstocks as well as organic solvents. Previous studies on the separation of the minimum-boiling azeotrope acetone-methanol by pressure-swing extractive distillation have shown superiority in terms of energy and cost savings. However, the pressure-varying configuration inevitably requires high-grade heat steam. To surpass the limitation, a novel different pressure extractive distillation strategy is proposed in this paper. The conceptual design of the different pressure extractive distillation configuration is carried out from thermodynamic insights, and the feasible ranges of entrainer/feed flow rate ratio and reflux ratio are determined. The design parameters are optimized by an improved non-dominated sorting genetic algorithm. Compared with the conventional extractive distillation process, the total annual cost (TAC) and CO2 emissions of the proposed process are reduced by 22.17% and 48.14%, respectively. An alternative different pressure extractive distillation process with feed preheating is then obtained by changing feed thermal condition, which has a 24.08% reduction in TAC and a 48.33% reduction in CO2 emissions in comparison with the conventional extractive distillation process. Compared with the existing heat-integrated pressure-swing extractive distillation process, the new process has a 2.90% and 22.36% reduction in TAC and CO2 emissions, respectively. Subsequently, two control schemes are presented by calculating controllability indicators in the steady-state design stage. The results illustrate that the improved control scheme with multiple feedforward control loops performs the best robustness.