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Pemisahan n-propil asetat dari campuran terner n-propil asetat/n-propanol/air merupakan salah satu proses yang tidak dapat dilakukan dengan distilasi sederhana. Adanya azeotrop terner minimum dari campuran tersebut menyebabkan n-propil asetat hanya dapat dipisahkan dari campuran n-propanol dan air salah satunya dengan metode distilasi ekstraktif. Distilasi ekstraktif merupakan proses vaporisasi parsial dengan menambahkan suatu agen pemisah non-volatil yang disebut sebagai sovent atau agen ekstraktif. Solvent yang digunakan dalam simulasi proses ini adalah campuran DMSO (Dimetil Sulfoksida) dan Gliserol dengan komposisi 50 % massa dengan perbandingan 1:2 untuk massa umpan kolom : solvent. Feed yang digunakan adalah n-propanol (10 kmol/jam) dan asam asetat (13 kmol/jam) masing-masing pada suhu 25°C dan tekanan 101,3 kPa. Hasil n-propil asetat terbaik diperoleh saat solvent diumpankan pada stage 5 dengan fraksi mol n-propil asetat pada distilat 0,9975 disertai dengan minimumnya energi reboiler yang digunakan pada konfigurasi kolom ini. n-Propyl acetate separation of the n-propyl acetate /n-propanol/water mixture composition can't be done by simple distillation. The existence of minimum ternary azeotrope on the mixture causes n-propyl acetate can be separated only by extractive distillation method. Extractive distillation is a partial vaporization process in the presence of a non-volatile separating agent called as solvent or extractive agent. Solvent used in the simulation process is DMSO (Dimethyl Sulfoxide)-Glycerol mixture (50% mass) with a ratio of 1: 2 for column feed : solvent. n-Propanol (10 kmol/hour) and acetic acid (13 kmol/hour) are fed into reactor (before extractive distillation process) at 25°C and 101.3 kPa, respectively. The best results of n-propyl acetate were obtained when the solvent was fed to stage 5 in which mole fraction of n-propyl acetate in distillate 0.9975 accompanied by the minimum reboiler energy used in this column configuration.

Octane and p-xylene are common components in crude gasoline, so their separation process is very important in petroleum industry. The azeotrope and near azeotrope are often separated by extractive distillation in industry, which can realize the recovery and utilization of resources. In this work, the vapor-liquid equilibrium experiment was used to obtain the vapor-liquid equilibrium properties of the difficult separation system, and on this basis, the solvent extraction mechanism was studied. The mechanism of solvent separation plays a guiding role in selecting suitable solvents for industrial separation. The interaction energy, bond length and charge density distribution of p-xylene with solvent are calculated by quantum chemistry method. The quantum chemistry calculation results and experiment results showed that N-Formylmorpholine is the best solvent among the alternative solvents in the work. This work provides an effective and complete solvent screening process from phase equilibrium experiments to quantum chemical calculation. An extractive distillation simulation process with N-Formylmorpholine as solvent is designed to separate octane and p-xylene. In addition, the feasibility and effectiveness of the intensified vapor recompression assisted extraction distillation are also discussed. In the extractive distillation process, the vapor recompression-assisted extraction distillation process is globally optimal. Compared with basic process, the total annual cost can be reduced by 43.2 %. This study provides theoretical guidance for extractive distillation separation technology and solvent selection.

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.

Background After ammoniation of propacetamol hydrochloride, the liquor contains an azeotropic mixture of acetone and diethylamine. The mixture must be separated to reuse the solvent and the raw material. However, the separation of acetone and diethylamine is difficult because the boiling point difference is only 0.6°C. Methods In this study, the mechanism of separating azeotropes was studied by quantum chemical calculations of the σ-profiles, interaction energy and molecular conformation. The vapor-liquid equilibrium data were supplemented by experimental analysis of the vapor-liquid equilibrium for cyclohexanol and diethylamine. The relative volatility of the light and heavy components of the azeotrope was investigated after adding the solvent. Sequential iteration method was used to optimize the extractive distillation process. The parameters in process such as the feeding position, number of stages and the amount of solvent are optimized, and the minimum total annual cost is obtained. Significant findings The results showed that the two-column feed preheating extractive distillation process was the lowest. The results showed that the two-column feed preheating extractive distillation process afforded the lowest total annual cost. Thermodynamic and environmental analyses showed that the two-column feed preheating extractive distillation process afforded good energy-saving, with minimal environmental impact. This study is significant for implementing the extractive distillation process for azeotrope separation and the sustainable development of acetone and diethylamine products.

To develop efficient ionic liquid (IL)-based separation processes like extractive distillation, the knowledge of IL-involved vapor–liquid equilibria (VLE) is necessary. Since experimental measureme...

In this work, a novel sequential approach for optimal conceptual design of extractive distillation columns for the separation of ternary azeotropic mixtures was developed. This approach is based on...

The vapor–liquid phase equilibrium (VLE) data for binary systems of: n-hexane + methylcyclopentane, n-hexane + N-methylpyrrolidone (NMP), methylcyclopentane + NMP and ternary system of n-hexane + methylcyclopentane + NMP were determined with a modified Rose still at atmospheric pressure (101.3 kPa), and all the binary data passed the Wisniak area test and Van Ness point test, which accorded with the thermodynamic consistency. Three thermodynamic models Wilson, NRTL and UNIQUAC were used to correlate binary data and get binary interaction parameters, then the built-in parameters of the Aspen Plus software were replaced by the obtained model parameters to estimate the ternary data of n-hexane + methylcyclopentane + NMP. The estimation values of the three models are in good agreement with the experimental data. Moreover, the effect of NMP was analyzed, and it found to be an effective candidate extractant for the extractive distillation of n-hexane + methylcyclopentane.

Selective agents for the extractive distillation of an acetone–methanol–chloroform–tetrahydrofuran mixture are selected, based on results from analyzing arrays of composition–excess molar Gibbs energy data. The base quaternary system contains eight azeotropes of different types. Data on vapor–liquid equilibria and excess molar Gibbs energy at 101.32 kPa are calculated for k-component constituents (k = 2–5) of acetone–methanol–chloroform–tetrahydrofuran–testing agent derivative systems. The possibility of choice selective agents for the extractive distillation of an acetone–methanol–chloroform–tetrahydrofuran mixture based on results of analyzing the concentration dependences of the excess molar Gibbs energy of binary systems formed by the components and testing agents in the conditions of separation is shown.

Background: Economically recovering valuable cyclohexane and sec-butyl alcohol from wastewater is an important industrial problem worthy of research and investigation. The available separation flowsheet in open literature was a heat pump assisted four-column scheme combining heterogeneous azeotropic and extractive distillation. However, the above design achieves significant energy saving at the cost of huge capital investment and increased operational complexity involved in the compression system. The purpose of this paper is to develop an improved configuration for separating the ternary system without using the expensive compression system, and it can also significantly improve the economics. Methods: The core design concept of our proposed three separation flowsheets is to fully utilize the advantage of the heterogeneity of the ternary system by introducing the fresh feed into a decanter for natural liquid-liquid splitting and innovatively applying a direct-contact heat exchanger to preheat the fresh feed. Besides, the technologies of dividing-wall column, side-stream extractive distillation and heat integration are also integrated to the heterogeneous azeotropic and extractive distillation for further energy saving. Significant findings: In comparison with the existing design, our final proposed heat-integrated heterogeneous distillation process with two dividing-wall columns can significantly save energy consumption 24.5%, total annual cost 43.6% and CO2 emission 13.2%.

Acetone and n-heptane are common solvents in the pharmaceutical industry and they have been found in wastewater. Under atmospheric conditions, the mixture of these compounds creates a minimum-boiling azeotrope. The extractive distillation process with a high boiling solvent is commonly utilized to separate the azeotropes in the industry to minimize waste, reuse resources, achieve clean production, and preserve the environment. In this work, extractive distillation was applied to separate the binary azeotropic system of acetone and n-heptane in wastewater using butyl propionate as a solvent. The characteristics of the process are designed and simulated via Aspen Plus. The simulation results showed that to get a distillate containing at least 99.5 mass% acetone, a solvent-to-feed ratio of 1.4, a reflux ratio of 1.5, a number of stages of 30, a feed stage of 26, a solvent stage of 10, and a solvent temperature of 298.15 K were required. The optimum operating parameters of the process were also obtained using the NLP optimization method, with the minimum total annual cost as the objective function. While the process was operating in optimal mode, CO2 emissions were calculated to be 0.0780 kg CO2/kg feed.

Objectives.To investigate the influence of side-section flow modes on the energy efficiency of apartially thermally coupled distillation sequence (PTCDS) with a vapor recompression heat pumpfor the extractive distillation of an allyl alcohol–allyl acetate mixture with n-butyl propionate andidentify modes under which the combined use of a PTCDS and heat pump are the most efficient.Methods.Mathematical modeling in the Aspen Plus V10 software package was used as the mainresearch method. The local composition equation of the non-random two-liquid model was usedas a model for describing the vapor–liquid equilibrium, while the Redlich–Kwong model was usedto consider the non-ideal vapor phase. When modeling the conventional extractive distillationscheme and PTCDS, parametric optimization was carried out according to the criterion of the totalenergy costs in the column reboilers. For the economical evaluation, Aspen Process EconomicAnalyzer V10.1 tools were used.Results.For extractive distillation of a mixture of allyl alcohol (30 wt %) and allyl acetate (70 wt %)with n-butyl propionate as an entrainer, the minimum energy consumption was achieved at thesame side-section flow mode for the variants of a PTCDS with and without a heat pump. Thereduction in energy costs relative to the conventional scheme was 20% for the sequence withouta heat pump and 38% for that with a heat pump. An economic assessment was made of thebest options in comparison with the conventional extractive distillation scheme. The PTCDS witha heat pump had an advantage over the sequence without a heat pump only for long periods ofoperation.Conclusions.For the extractive distillation of an allyl alcohol–allyl acetate mixture, the optimalmodes for the combined use of a PTCDS with a vapor recompression heat pump coincide with theoptimal modes for a PTCDS without a heat pump.

Recently, a new industrial relevant wastewater (water/Cyclohexane/sec-butyl alcohol) separation process with vapor recompression and thermal coupling was proposed as the conventional homogeneous extractive distillation. This highly integrated and interactive multivariable process presents great challenges to the dynamic controllability and process safety analysis. In this paper, based on the concept of “simultaneous design”, the newly proposed process is systematically investigated from the perspective of process improvement, plantwide control and safety analysis. Firstly, for energy conservation and CO2 emission reduction, the new complex process is further improved by applying the features of heterogeneous distillation. And a modified heterogeneous distillation process with heat pump is proposed, which can save reboiler duty about 16.8 % and save compressor electricity up to 67.7 %, while the reduction of CO2 emissions is 23.5 %. Secondly, for the efficient heterogeneous distillation process, an effective and robust plantwide control strategy is developed and tested under large throughput and feed composition disturbances. Last, with the dynamic simulation assisted HAZOP, a quantitative safety analysis is conducted, which can help experts to consider the nature, scale and response time of hazards and identify the potential propagation of deviation between different units, and then propose more specific or accurate safety recommendations correspondingly.

Extractive distillation is widely accepted and commercialized for separating azeotrope mixtures, but using traditional organic solvents leads to intrinsic obstacles such as the high energy requirement and solvent-related environmental problems. Benefiting from the development of green solvents, using ionic liquids instead of traditional solvents as entrainers for extractive distillation has attracted wide attention. This paper presents a multi-objective optimization strategy to integrate the design and control of the ionic liquid-based extractive distillation processes. In the optimization processes, the condition number (CN) and total annual cost (TAC) are minimized as the objective functions to evaluate the control properties and design of three different separation systems. The optimization results are shown by the Pareto front, which is based on trade-offs between controllability and economics. The environmental impact is evaluated by the environmental impact potential of energy for each system in a posterior stage during the optimization processes. Designs with minimum TAC (PT), trade-off designs between TAC and CN (PO) and designs with minimum CN (PC) on Pareto front are optimized and compared. The results show that the increase of reflux ratio can improve the control properties for the ionic liquid-based extractive distillation processes. Furthermore, the dynamic simulation of PT and PO are carried out to compare their dynamic responses based on the same dynamic control structure, and PO shows better performance in the aspects which include maximum deviation and residual error of dynamic response.

Simulation studies of n-heptane/toluene system were performed using Aspen Plus. The comparative study of different entrainers: N-Methyl-2-Pyrrolidone (NMP), Phenol, and Sulfolane for separation of this system was done. Sensitivity analysis was carried out to optimize flowsheets. The criteria to determine the appropriate solvent for the said system included, the total cost calculated by the Aspen Process Economic Analyzer, amount of the solvent consumed, cost of the solvent, and purity obtained during the separation process. For the given system, sulfolane was found to be the appropriate solvent.

A comparative analysis of energy consumption for extractive distillation flowsheets was carried out. This was done by the example of methanol - ethanol - acetonitrile - mixture. These solvents are used in pharmaceutical industries. The basic system methanol - ethanol - acetonitrile - water contains four binary and one ternary minimum-boiling azeotropes. Pressure change has almost no effect on the location of separatric surfaces. Therefore, extractive distillation should be used to separate solvents mixtures of any composition. Industrial entrainers dimethyl sulfoxide and glycerol are considered as selective agents. The effect of entrainer on vapor-liquid equilibrium at 30 and 101.32 kPa was evaluated by the relative volatility of the components forming azeotropes and the selectivity of the agents. The simulation was carried out on the Aspen Plus V.10.0 program environment. Two extractive distillation flosheets for the methanol - ethanol - acetonitrile - water separation are investigated. Both schemes include a two-column complex for the extractive distillation of the base mixture: in the first column, organic solvents are separated from water, and in the second column, the agent is regenerated. For subsequent separation of acetonitrile, extractive distillation with dimethyl sulfoxide or glycerol is also used. But separation of methanol-ethanol - entrainert zeotropic mixtures differs in the order of separation of components in schemes I and II. In scheme I, regeneration of the agent and further separation of the alcohol mixture is provided, in scheme II, methanol is first isolated, and then ethanol is separated from the agent. The optimized results for both schemes at columns pressures 30 and 101.32 kPa are performed. Different sets of selective agents introduced into extractive distillation columns are considered. The concept of an effective set of entrainers is introduced. The evaluation of the design alternatives need the assessment of energy demands. Total energy consumption for separation (reboiler duty) for the scheme II at 35-38% higher than values for scheme I. On the criterion of the minimum total energy consumption for the separation the scheme I was recommended: pressure columns 30 kPa, effective set of entrainers: glycerol for dehydration of the base mixture and dimethyl sulfoxide for acetonitrile isolation.

This article investigates the performances of different extractive distillation processes intensified with dividing-wall column for separating benzene-isopropanol-water ternary mixtures. All the processes with ethylene glycol as solvent are optimized with the minimal total annual cost (TAC) as target. In order to get the global optimal solution intelligently, an improved simulated annealing algorithm is adopted, which is programmed in MATLAB and linked to Aspen Plus. The results show that the extractive dividing wall column-solvent (EDWC-S) process consisting of an extractive dividing wall column and a solvent recovery column is the best scheme. It can reduce the TAC by 28.65% and CO2 emissions by 32.84% compared to the conventional triple-column extractive distillation process.

In this work, we firstly report on the rigorous design, optimization, and carbon emission analysis of the processes separating acrylonitrile (AN), acetonitrile (AC), and water. Two bi-sectional processes, which integrate heterogeneous extractive distillation with hybrid extraction-distillation (the HHED process), and that with pressure swing distillation (the HPSD process), are proposed. Compared with the existing configuration, operation using 30% less entrainer amount is found feasible for both processes, leading to 9.8% energy saving. Also, the optimized HHED process saves 4.8% total annual cost (TAC) and 5.8% carbon emission from the optimized HPSD process. Besides, implementing a vapor recompression cycle on the optimized HHED process reduces 31.1% CO2 emission but increases 6.6% of TAC. On the other hand, the heat-integrated HPSD process with an economizer design does not outperform the non-integrated HHED process. Finally, separation using heterogeneous azeotropic distillation or hybrid extraction-distillation process in single is conceptually rejected. Through this work, the industrial guidance could be provided.

To obtain the production of propylene oxide (PO) with high purity, a coupled azeotropic and extractive separation process is proposed to remove the impurities such as aldehyde, methanol, methyl for...

Dimethyl carbonate is an eco-friendly essential chemical that can be sustainably produced from CO2, which is available from carbon capture activities or can even be captured from the air. The rapid increase in dimethyl carbonate demand is driven by the fast growth of polycarbonates, solvent, pharmaceutical, and lithium-ion battery industries. Dimethyl carbonate can be produced from CO2 through various chemical pathways, but the most convenient route reported is the indirect alcoholysis of urea. Previous research used techniques such as heat integration and reactive distillation to reduce the energy use and costs, but the use of an excess of methanol in the trans-esterification step led to an energy intensive extractive distillation required to break the dimethyl carbonate-methanol azeotrope. This work shows that the production of dimethyl carbonate by indirect alcoholysis of urea can be improved by using an excess of propylene carbonate (instead of an excess of methanol), a neat feat that we showed it requires only 2.64 kW·h·kg−1 dimethyl carbonate in a reaction-separation-recycle process, and a reactive distillation column that effectively replaces two conventional distillation columns and the reactor for dimethyl carbonate synthesis. Therefore, less equipment is required, the methanol-dimethyl carbonate azeotrope does not need to be recycled, and the overall savings are higher. Moreover, we propose the use of a reactive distillation column in a heat integrated process to obtain high purity dimethyl carbonate (> 99.8 wt-%). The energy requirement is reduced by heat integration to just 1.25 kW·h·kg−1 dimethyl carbonate, which is about 52% lower than the reaction-separation-recycle process. To benefit from the energy savings, the dynamics and control of the process are provided for ±10% changes in the nominal rate of 32 ktpy dimethyl carbonate, and for uncertainties in reaction kinetics.

An energy-efficient triple-column extractive distillation process is developed for recovering tetrahydrofuran and ethyl acetate from industrial effluent. The process development follows a rigorous hierarchical design procedure that involves entrainer design, thermodynamic analysis, process design and optimization, and heat integration. The computer-aided molecular design method is firstly used to find promising entrainer candidates and the best one is determined via rigorous thermodynamic analysis. Subsequently, the direct and indirect triple-column extractive distillation processes are proposed in the conceptual design step. These two extractive distillation processes are then optimized by employing an improved genetic algorithm. Finally, heat integration is performed to further reduce the process energy consumption. The results indicate that the indirect extractive distillation process with heat integration shows the highest performance in terms of the process economics.

This work has been carried out to simulate a binary distillation column to separate Benzene and Toluene from BT fraction using Aspen Plus software. Benzene–Toluene separator is a normal two-phase distillation for pure aromatics. In Steel Plant, crude benzol recovered from the coke gas is fed to the Benzol Plant where benzolised oil undergoes benzol distillation, hydro-refining and extractive distillation and aromatic stripping column to produce pure BT fraction which is further pumped to BT Separation column in order to produce pure Benzene as top product and pure toluene as bottom product. This benzene is used mainly as an intermediate to make other chemicals and used in manufacture of drugs, dye, rubber, detergents, plastic and polymers. Thus, an attempt has been made to increase the production of high-purity Benzene and Toluene at optimum condition using Aspen Plus. In this paper, the feed flow rate, reflux rate and column stages are optimized using Aspen Plus as well validated by using Mc-Thile and Ponchon Savarit Method, while keeping the feed temperature and pressure constant. The purity of Benzene and Toluene is achieved as 99.99% and 99.70%, respectively, at different conditions such as feed flow rate 3165 kg/h, reflux rate 1.2 kg/h, temperature 80 °C and pressure 0.7 kg/cm2. This high purity of solvents is achieved at 60th stage, whereas current running plant achieved the same purity at 65th stage. As compared to current running condition of the plant, the production rate of benzene is achieved 43%more than the existing plant data. At these optimized condition high purity and high production are achieved at expense of less energy consumption. It is validated by running the process in the industry at same conditions using the distillation column. The data almost matched with the simulated data.

As there is an azeotropic point between methanol and ethyl formate, they cannot be completely separated by ordinary distillation. In this paper, extractive distillation was applied and dimethyl sul...

Stochastic optimization is inefficient, although it shows robustness against local optimum and can guarantee high-quality solutions. Parallel computation can be a promising way to improve the efficiency of stochastic optimization. However, the common environments do not support calling multiple simulators through the win32com interface, which hinders parallel computation. As a countermeasure, this study proposes a population-distributed differential evolution (DDE) framework, which combines multiple optimizers through the shared message passing medium. The framework distributes the population into groups (subpopulations) on different threads by a pool model, which can make full use of a multi-core CPU and significantly accelerate the computation. Moreover, we considered both the synchronously and asynchronously distributed differential evolution. Three case studies (benzene/toluene/xylene conventional distillation, acetone/methanol/water extractive distillation, and heat pump assisted dividing-wall column separating benzene/toluene/xylene) are optimized to show the superior performance of the DDEs. The parallel framework can reduce the computing time by ∼70% on a 4-core CPU, which is a significant improvement. DDEs cause some parallel efficiency loss, which is 5–10% and 10–20% for ADDE and SDDE, respectively. Further, based on time consumption analysis, we explain the reasons for the efficiency loss.

N-propanol and benzene are important chemical organic compounds, which widely exist in wastewater of chemical industry, medicine and other fields. Because they form azeotrope with water, extractive distillation was used to separate them. In order to increase the efficiency of energy utilization, vapor recompression technology was added on the basis of extractive distillation. On the basis of vapor recompression assisted extractive distillation, energy integration was carried out according to pinch technology, and the optimal energy utilization method was found. The exergy loss and gas emission of each process were studied and analyzed. The results show that the vapor recompression assisted distillation process with feed preheating can reduce the heat duty and gas emissions, and improve exergy efficiency and economic performance. Therefore, the vapor recompression assisted distillation process with feed preheating can effectively treat the wastewater containing benzene / n-propanol. It has the advantages of low cost, energy saving and environmental protection, which is of great significance to the development of environmental protection industry.

The extractive distillation process is gradually being used for the desulfurization of fluid catalytic cracking (FCC) naphtha because of its excellent octane number protection performance during de...

BACKGROUND: Although phenol is a key intermediate in the plastics and polycarbonate industry, it is also a toxic component that requires removal from dilute aqueous streams, potentially by liquid–liquid extraction (LLX). For LLX, cumene is suggested as a solvent as it is already present in processes in the polycarbonate industry. For the recovery of cumene from phenol by distillation, knowledge on vapor–liquid equilibrium (VLE) behavior is important, in combination with how this is affected by other components possibly present as an impurity or explicitly added as a solvent. This was investigated in this work. RESULTS: The binary cumene–phenol system shows a tangent pinch in the binary VLE diagram. Addition of a range of impurities and solvents showed that hydrogen bond accepting compounds strongly improve the relative volatility of the mixture, whereas dodecane, not capable of forming hydrogen bonds, has a negative effect on the relative volatility. CONCLUSION: Addition of polar components with hydrogen bonding abilities, i.e. ketones or ethers, affected the relative volatility of cumene over phenol the most positively. Combining two types of components results in similar effects, and clear synergistic effects could not be shown based on current VLE measurements. Addition of an apolar component in combination with polar components with hydrogen abilities had only a minor effect on the relative volatility.

Extractive distillation (ED) can be used to separate mixtures with low relative volatilities that are even close to unity. It is widely adopted for the separation of aromatics and nonaromatics in t...

Cyclohexane and sec-butyl alcohol are widely used in the pharmaceutical and chemical industries. The separation of cyclohexane/sec-butyl alcohol/water azeotropic mixture is of great significance for mitigating environmental risk, recycling solvents, and maintaining developmental sustainability. Based on the COSMO-SAC model, the infinite dilution activity coefficients of the components were calculated, and the final solvent was further obtained by relative volatility and solvent power screening. Taking the total annual cost as the objective function, the extractive distillation process is optimized based on a sequential iterative optimization algorithm. To further reduce the process energy consumption, several energy-saving processes were explored. Energy-saving processes are compared in terms of total annual cost, CO2 emissions, and thermodynamic efficiency. It was found that the total annual cost and thermodynamic efficiency of the processes show an increasing trend, while CO2 emissions show a decreasing trend. The results of stage-exergy indicate that the processes with heat pump are relatively small. The heat pump combined with the thermal coupling extractive distillation process exhibits better thermoeconomic and environmental performance. It provides theoretical guidance for improving the separation and recovery of value organics and energy-saving optimization of processes, which conforms to the theme of sustainable and environmental development.

The separation of a ternary mixture containing methyl methacrylate (MMA)-methanol-water is challenging owing to MMA forming a ternary azeotrope with methanol and water. Herein, water was employed a...

Orange processing generates a high amount of waste rich in natural compounds that can be used to obtain added-value products or as raw material in biorefineries. Limonene (terpene) and linalool (ox...

Objectives. Determination of the effectiveness of using various types of heat pumps in the extractive distillation of an isobutyl alcohol–isobutyl acetate mixture with n-butyl propionate as the entrainer.Methods. As the main research method, mathematical modeling was performed using the Aspen Plus V. 9 software package. As a model for describing the vapor–liquid equilibrium, the local composition equation-based UNIQUAC model was employed, and the Redlich–Kwong model was adopted to examine the non-ideal vapor phase. When modeling the conventional scheme of extractive distillation, parametric optimization was carried out according to the criterion of total energy costs in the reboilers of the columns. For economical evaluation, Aspen Process Economic Analyzer V10.1 tools were employed. Results. In comparison with the conventional extractive distillation scheme, three variants of schemes with vapor-recompression heat pumps were considered: with a heat pump placed on an extractive distillation column, on an extractive agent regeneration column, and with two heat pumps placed on both columns of the scheme. A scheme with an internal heat pump was also proposed, in which the heat pump compressor is located between sections of extractive columns that operate at different pressures: 506.6 kPa in the top sections and 101.3 in the bottom section. An economic analysis was conducted for all the considered schemes to calculate the total annual costs. It was shown that schemes with vapor-recompression heat pumps can significantly reduce the energy costs of extractive distillation by up to 39.6%; however, a significant reduction in the total annual costs is achieved only with sufficiently long operation periods of the plants. The reduction in the energy costs in the scheme with an internal heat pump was 44%, and the total annual costs were in the range of 20.2–30.1%, depending on the operating time of the plant. Conclusions. It was shown that using heat pumps in the extractive distillation of the mixture of isobutyl alcohol–isobutyl acetate with n-butyl propionate as the entrainer can significantly reduce energy costs. The scheme with an internal heat pump is the most economical of all the considered schemes.

The paper is devoted to the development of diethyl ether + hexane + ethyl acetate + ethanol mixture (solvents of the dihydroquercetine production) separation flowsheets based on the analysis of the structure of the phase diagram. The phase equilibrium of the quaternary system was studied using mathematical modeling in the AspenPlus. The parameters of Non Random Two Liquid model allow reproducing vapor-liquid equilibrium data and azeotropes characteristics with a relative error not exceeding 5%. It was shown that the system was characterized by the presence of three binary azeotropes and the phase diagram was divided into three distillation regions. Based on a literature analysis N-methyl-2-pyrrolidone was selected as a solvent for the extractive distillation. The selectivity of the separating agent was calculated and it was shown that N-methyl-2-pyrrolidone influenced the relative volatility of components to varying degrees. Two flowsheets containing a diethyl ether separation column and two extractive distillation complexes were proposed. The flowsheets differ in the sequence of separation of the components: hexane, ethyl acetate and ethanol. The distillation process was simulated and the operating column parameters (number of stages, feed stage, reflux ratio, solvent to feed volume ratio) were determined. Selected parameters meet the minimum energy consumption. An energy-efficient separation variant was chosen.

CO2 enhanced oil recovery (CO2-EOR) has been widely used in oil field exploitation in recent years. The injections of CO2 and ethane are easy to form an azeotrope, which makes difficult recovery of...

The performance and effectiveness of the conventional and heat-integrated side-stream extractive distillation arrangements are explored with the simultaneous consideration of the steady-state economics, thermodynamics and dynamic controllability aspects of the process. The overall performance of simple stream-to-stream heat-integrated F-S-E configuration (serially preheating column inlet feeds by solvent stream) is superior to others because of the least total annual cost (TAC), CO2 emissions and highest second-law efficiency among these side-stream cases. It can further reduce 8.16% in TAC compared to the conventional extractive distillation configuration. Exergy and entropy generation analyses are employed in these heat-integrated side-stream extractive distillation arrangements to thorough evaluate the energy degeneration in each component. Furthermore, dynamic control analyses for conventional and heat-integrated side-stream extractive distillation processes are also explored. Two novel compromised tactics are proposed to make the economically optimal heat-integrated arrangement more stable at rejecting large feed disturbances according to the physical implemented issues of economizers. Both effective and robust dual-product quality controls are provided for tackling the large (20%) throughput and feed composition perturbations. Furthermore, a new developed control scheme with parallel arrangement works better than that with series exchangers’ arrangement by comprehensively weighing results of steady-state economic design and dynamic controllability.

Ethyl acetate is a vital chemical raw material and is usually produced by esterification in industry. But this reaction can produce multiazeotrope mixtures of ethyl acetate/ethanol/water. In this work, triple column pressure-swing distillation process with and without heat integration and hybrid processes combining extractive distillation and pervaporation are proposed to separate a mixture of ethyl acetate/ethanol/water. Furthermore, the three processes are comprehensively compared with the triple-column extractive distillation process. Based on minimization of the total annual cost, the parameters of the all processes are optimized. The triple-column extractive distillation process has the greatest economic advantage. Additionally, the performances of the all processes in environmental protection and energy efficiency are evaluated. The energy efficiency of the combined extractive distillation and pervaporation unit process is relatively low, but its environmental impact is the lowest among the four processes.

BACKGROUND: tert‐Butanol (TBA) and water form an azeotrope at atmospheric pressure. Therefore, extractive distillation was adopted to separate the azeotropic mixture. As a new kind of solvent, the ionic liquids (ILs) 1,3‐dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and 1‐ethyl‐3‐methylimidazolium diethylphosphate ([EMIM][DEP]) were chosen to break the azeotropic point in extractive distillation. RESULTS: For the ternary mixture of TBA + water + ILs, the isobaric vapor–liquid equilibrium data at atmospheric pressure for three IL mole fractions (0.1, 0.2 and 0.3) were measured. The results indicated that the volatility of TBA relative to water became higher after [MMIM][DMP] or [EMIM][DEP] was added. The nonrandom two‐liquid (NRTL) model and the COSMO‐RS theory were used to predict the ternary experimental data. The predicted results from the NRTL model showed good agreement with the experimental data. The predicted results from COSMO‐RS showed that the vapor‐phase mole fraction basically agreed with the experimental data and the equilibrium temperatures were lower than the experimental data. σ‐Profiles, σ‐potentials and σ‐surfaces were calculated based on COSMO‐RS. The results were the same as for the experiments, namely the interaction between water and ILs was stronger than other interactions; the affinity of water and [MMIM][DMP] was stronger than that of water and [EMIM][DEP]. CONCLUSIONS: The separation of the binary azeotrope of TBA and water was achieved after the ILs [MMIM][DMP] or [EMIM][DEP] were added. The separation ability of [MMIM][DMP] was better than that of [EMIM][DEP]. © 2020 Society of Chemical Industry

Methanol and methylal form a minimum boiling point azeotrope and cannot be separated by conventional distillation. In this paper, the azeotrope was separated by extractive distillation with cyclohe...

Ternary extractive distillation (TED) is an effective and sustainable separation process for treating pharmaceutical wastewater containing ethyl acetate/isopropanol/water, corresponding to three bi...

Ethyl propionate is usually produced from esterification of propionic acid and ethanol in the industry. However, the purification of ethyl propionate remains a challenge because the unreacted ethan...

Ionic liquids (ILs) have shown remarkable potential for applications in separation, such as extractive distillation and liquid–liquid extraction. Crucial to these applications is the estimation of ...

The mixture of water, methanol, and ethanol is frequently produced in the pharmaceutical industry. To separate the mixture by extractive distillation, the selection of entrainer is a crucial step. ...

In this study, a few extractive distillation processes with ethylene glycol as solvent are proposed to separate high-purity ethanol and tert-butanol from industrial effluents, including direct ED, indirect ED and heat pump assisted indirect ED. All these processes are optimized with targeting minimum annual total costs by a sequential iteration algorithm. After that, a head-to-head comparison is completed regarding distributions of cost, energy and CO2 emission. The results showed that the direct ED is the most economical process reducing minimum annual total costs by 30.15 % than the heat-pump assisted indirect ED, while the latter is the most energy-efficient process saving energy consumption and CO2 emissions by 14.78 % and 21.79 % than the direct ED.

BACKGROUND: The design and control of extractive distillation (ED) for separating azeotropes has been widely investigated. However, most researches only deal with simple binary azeotropes without considering impurities. In fact, in industrial practices, intermediate impurities can be removed as a side withdrawal from the extractive distillation column. The dynamic control of such processes has not been investigated. Furthermore, there are many heat‐integrated alternatives of basic ED sequence. When considering impurities withdrawn, the dynamic control of these alternatives may face some difficulties. Thus, this article aims to establish the effective control structures of ED processes for separating azeotropes with intermediate impurities, including basic sequence and heat‐integrated alternatives. Ethanol dehydration is selected to be explored, including a basic sequence (BS), a heat‐integrated sequence (HIS) which combines the pre‐concentration column and the entrainer recovery column into one column and the thermodynamic equivalent sequence of the HIS (TEHIS). Overall assessment of the dynamic performances of these sequences is implemented. RESULTS: For all the sequences, the dynamic performance with entrainer recycling stream being proportional to the extractive distillation column (EDC) feed is better than being proportional to the fresh feed. Meanwhile, large negative transient deviations in the water product purity and intensive fluctuations of sensitive‐stage temperatures can be observed for the HIS, but not for the TEHIS. CONCLUSIONS: The TEHIS is the best sequence considering both economics and dynamics. These sequences and the analyses of their dynamic controllability are valuable in practice for multicompoent azeotropes purification. © 2020 Society of Chemical Industry