Heterogeneous Azeotropic Distillation Research Articles

Techno-economic viability of bio-based methyl ethyl ketone production from sugarcane using integrated fermentative and chemo-catalytic approach: Process integration using pinch technology

Butanediols are versatile platform chemicals that can be transformed into a spectrum of valuable products. This study examines the techno-commercial feasibility of an integrated biorefinery for fermentative production of 2,3-butanediol (BDO) from sucrose of sugarcane (SC), followed by chemo-catalytic upgrading of BDO to a carbon-conservative derivative, methyl ethyl ketone (MEK), with established commercial demand. The techno-economics of three process configurations are compared for downstream MEK separation from water and co-product, isobutyraldehyde (IBA): (I) heterogeneous azeotropic distillation of MEK-water and extractive separation of (II) MEK and (III) MEK-IBA from water using p-xylene as a solvent. The thermal efficiency of these manufacturing processes is further improved using pinch technology. The implementation of pinch technology reduces 8% of BDO and 9–10% of MEK production costs. Despite these improvements, raw material and utility costs remain substantial. The capital expenditure is notably higher for MEK production from SC than BDO alone due to additional processing steps. The extraction based MEK separation is the simplest process configuration despite marginally higher capital requirements and utility consumption with slightly higher production costs than MEK-water azeotropic distillation. Economic analysis suggests that bio-based BDO is cost-competitive with its petrochemical counterpart, with a minimum gross unitary selling price of US$ 1.54, assuming a 15% internal rate of return over five-year payback periods. However, renewable MEK is approximately 16–24% costlier than the petrochemical route. Future strategies must focus on reducing feedstock costs, improving BDO fermentation efficacy, and developing a low-cost downstream separation process to make renewable MEK commercially viable.

Energy-efficient heterogeneous triple-column azeotropic distillation process for recovery of ethyl acetate and methanol from wastewater

The challenging separation of ethyl acetate (EtAC) and methanol (MeOH) from wastewater involves two azeotropes and a distillation boundary. Although extractive distillation (ED) has been explored, the heterogeneous region within the ternary azeotropic mixture has been overlooked, which suggests the possibility of using a decanter to cross the distillation boundary when the feed composition is present in the heterogeneous region. This study introduces a novel heterogeneous triple-column distillation (NHTCD) that eliminates the external solvent injection, simplifying the complex ED processes. The NHTCD process is developed via a systematic approach, comprising conceptual design based on thermodynamic insights and process optimization to determine the optimum configuration. Furthermore, heat integration (HI) and heat pump-vapor recompression (HP-VR) techniques were explored for energy conservation. Evaluation of energy, economic, and environmental (3E) aspects shows that the hybrid HP-VR with HI NHTCD process outperforms ED, achieving 87 %, 57 %, and 86 % reductions in energy, economic, and environmental emissions, respectively.

Energy-saving design and optimization of pressure-swing-assisted ternary heterogenous azeotropic distillations

A huge amount of energy is always consumed to separate the ternary azeotropic mixtures by distillations. The heterogeneous azeotropic distillation and the pressure-swing distillation are two kinds of effective technologies to separate heterogeneous azeotropes without entrainer addition. To give better play to the synergistic energy-saving effect of these two processes, a novel pressure-swing assisted ternary heterogeneous azeotropic distillation process is proposed firstly. In this process, the ternary heterogeneous azeotrope is decanted into two liquid phases before refluxed into the azeotropic distillation column to avoid the aqueous phase remixing, and three columns’ pressures are modified to decrease the flowrates of the recycle streams. Then the dividing wall column and heat integration technologies are introduced to further reduce its energy consumption, and the pressure-swing assisted ternary heterogeneous azeotropic dividing wall column and its heat integration structure are achieved. Genetic Algorithm procedure is employed to optimize the proposed processes. The design results show that the proposed processes have higher energy efficiencies and lower CO2 emissions, compared with the published ternary heterogeneous azeotropic distillation process.

Dehydration of Isopropanol: A Comparative Review of Distillation Processes, Heat Integration, and Intensification Techniques

The dehydration of isopropanol (IPA) is a crucial process in numerous industries, and the optimization of its efficiency and economic viability is essential. This review provides a comprehensive analysis and comparison of various distillation processes, heat integration (HI) strategies, and process intensification (PI) techniques employed for IPA dehydration. The advantages, limitations, and applicability of distillation processes, such as extractive distillation, heterogeneous azeotropic distillation, and pressure swing distillation, are discussed. In addition, this review explores the potential of HI techniques to optimize energy consumption and reduce operating costs of IPA dehydration processes. PI techniques, including thermally coupled arrangements and dividing wall columns, are examined for their ability to improve the process efficiency and sustainability. It is crucial to conduct thorough evaluations, as well as energy and economic analyses, when choosing the appropriate distillation process, HI approach, and PI technique for specific IPA dehydration applications. This review emphasizes the potential for improving the energy efficiency, product purity, and cost-effectiveness of IPA dehydration through the integration of advanced distillation processes and PI techniques.

Control of fully heat-integrated pressure-swing distillation with strict pressure manipulation: A case study of separating a maximum-boiling azeotrope with small pressure-induced shift

Pressure-swing distillation (PSD) is an alternative configuration used to separate pressure-sensitive azeotropes and avoid product contamination(s) in extractive or heterogeneous azeotropic distillation via the entrainer(s). Full heat integration between high- and low-pressure columns (HPC and LPC) can provide significant energy savings compared to the conventional case, while it also loses the control degree of freedom, trim condenser or reboiler heat load, via the integrated condenser/reboiler exchanger. Typically, the pressure of HPC is left uncontrolled, and additional pressure-compensated control strategies are implemented, which may create safety issues. To address this, the study proposes adding an auxiliary cooling-water-driven condenser to the fully heat-integrated PSD system, providing an extra manipulated variable to regulate the pressure of HPC. Compared to the conventional PSD system, the new modified process could achieve a 26.31% reduction in total annual cost. The research uses the maximum-boiling azeotropic mixture of acetone/chloroform as a case study which makes the distillation system characterized by high reflux ratios and a large recycle flow rate, leading to the unwelcome snowball effect. To achieve effective process control, robust control structures are proposed that rigorously regulate the pressure of the column by manipulating the heat removal in the trim condenser, attenuating or eliminating potential overpressure issues. Product purity and other evaluation indicators, such as product transient deviations, offsets, integral absolute error, and oscillation degrees, are also considered. Results show that the proposed control schemes can efficiently control the pressure of HPC, weaken the snowball effect, and maintain product purity. This study highlights the importance of pressure control for fully heat-integrated PSD systems, particularly for pressure-sensitive azeotropes with small pressure-induced shifts.

Application and Development of Heterogeneous Azeotropic Distillation

Application and Development of Heterogeneous Azeotropic Distillation

Dehydration of IPA-H2O mixture: Review of fundamentals and proposal of novel energy-efficient separation schemes

According to the ongoing regulations, the need to identify green and economical production roots for fuels is of paramount importance. Unfortunately, biofuels production is often accompanied with the formation of water, that needs to be removed energy-efficiently. To achieve this separation, extractive and conventional heterogeneous azeotropic distillation have been extensively studied, but these solutions are usually high energy-demanding when non-negligible water content is involved. In view of introducing significant energy savings for the alcohol dehydration, this work focuses on the analysis of two innovative separation schemes: one based on heterogeneous azeotropic distillation with binary azeotrope and the other based on liquid–liquid extraction combined with distillation. For the sake of example, the proposed alternatives have been applied to the isopropanol-water mixture.The performances of the new configurations are assessed in terms of energy consumption and compared with conventional heterogeneous azeotropic distillation, proving the energy saving of the two proposed layouts.

Heterogeneous phase diagram and residue curve map for ethanol-water-ethyl acetate and ethanol-water-ethyl acrylate system

Heterogeneous phase diagram and residue curve map data are simulated using NRTL equation which are useful for design of heterogeneous Azeotropic distillation column. Simulated data are compared with experimental data.

Application of dividing wall column in azeotropic distillation with intermediate boiling-point heteroazeotrope: Simulation and optimization

Dividing wall column (DWC), as a proven process intensification technology, has been used widely in separation of ideal multi-components, and some azeotrope systems. For heterogeneous azeotrope with the potential possibility of crossing distillation boundary by liquid-liquid splitting, it is advantageous to integrate liquid-liquid decanter with distillation column, especially with DWC to further simplify flowsheets and reduce energy consumption. In this work, existing heterogeneous azeotrope separation processes are described, and an innovative DWC-based process (MHADWC) is proposed for intermediate boiling-point heteroazeotropic systems. Then an industrial case of MIPK system, is used to evaluate mentioned configurations by rigorous simulation and optimization. These configurations are compared and analyzed in detail on energy consumption, exergy analysis and equipment invest. The results show that, from the perspective of process energy consumption, MHADWC process has the most advantages, because it saves 37% of energy consumption; if both equipment costs and exergy recovery are taken into account, HADWC2 has a higher thermodynamic efficiency (43.5%) at its TAC and can be used as a preferred target. And in this work, purification of an intermediate boiling-point heteroazeotrope is the main difference of these processes compared with the well-known heterogeneous azeotropic distillation process where the top vapor product is the lowest boiling point of the ternary system.

Heterogeneous Azeotropic Extractive Coupled Heat Pump Distillation for Triethylamine‐Dichloromethane‐Acetone‐Water

AbstractThere are three kinds of binary azeotropes and one kind of a near‐boiling compound with clamping zone characteristics in the triethylamine‐dichloromethane‐acetone‐water system, which belongs to complex quaternary systems. A four‐column distillation process of heterogeneous azeotropic extraction for the separation of the system was designed, simulated, and optimized to obtain more suitable process parameters and energy consumption distribution of each column. On this basis, taking the total annual cost (TAC) as the comprehensive economic evaluation index and CO2 emission as the environmental evaluation index, the thermal integration technology and mechanical vapor recompression (MVR) heat pump technology were applied to the energy‐saving research of the distillation process for the system. The results indicate that compared with the conventional four‐column heterogeneous azeotropic extractive distillation process, the thermal integration distillation process and single‐column MVR heat pump coupled thermal integration distillation process can save energy consumption and TAC, and it can reduce CO2 emission.

Investigation on energy-efficient heterogeneous pressure-swing azeotropic distillation for recovery of cyclohexane and tert-butanol from industrial effluent

This paper highlights the separation of cyclohexane/tert-butanol from industrial effluent by heterogeneous pressure-swing azeotropic distillation based on the properties of pressure-sensitive distillation boundaries and natural liquid–liquid separation. There is no excess component in the separating process. The optimal parameters of the conventional process are obtained by using the simulated annealing algorithm. Additional heat pump and heat integration strategies are introduced into the process with the optimal operation parameter to save more energy. Evaluation indicators, such as total annual cost (TAC), total energy consumption (TEC), gas emission, and exergy destruction, are used to assess the potential of economic and environment friendly processes. The heat pump assisted HADPSD process employing auxiliary reboilers and heat integration is the optimal energy-saving process, exhibiting decreases of 41.98%, 55.32%, 52.30%, and 55.26% for TAC, TEC, gas emission, and exergy destruction compared to conventional HADPSD.

Sustainable design and optimization of the recovery process of acetic acid from vinasse: Operational, economic, and environmental analysis

Acetic acid production through biological routes has gain attention as an alternative to catalytic processes and, currently, 10% of the world production come from biological processes. It is a by-product of ethanol production through fermentation, but its recovery faces challenges such as high-water content and the presence of other organic acids. Therefore, the aim of the present work is to develop the optimal design of the recovery process of acetic acid from vinasse through liquid-liquid extraction followed by heterogeneous azeotropic distillation. Three configurations were evaluated: Conventional (CONV); Full-Heat Integrated (FHINT); and Mechanical Vapor Recompression (MVR). The total annual cost (TAC) was optimized using the genetic algorithms method. The MVR configuration presents the lowest TAC, but the capital cost of this process is high when compared to the other configurations. The CONV configuration, even with the lowest CAPEX, does not present good economic and environmental indicators. The FHINT configuration had intermediate OPEX, and slightly higher CAPEX compared to the CONV configuration. If payback is not a decisive factor, the MVR configuration is the most suitable due to its excellent operational and environmental indicators; but if so, the FHINT configuration is more suitable due to its lower CAPEX.

Investigation of energy-efficient heat pump assisted heterogeneous azeotropic distillation for separating of acetonitrile/ethyl acetate/n-hexane mixture

The conventional distillation is hard to accomplish the separation of acetonitrile/ethyl acetate/n-hexane mixture. Herein, a heterogeneous azeotropic distillation (HAD) without adding entrainer is proposed to separate ternary mixture. The proposed scheme is optimized via the simulated annealing algorithm and minimum total annual cost (TAC) is used as objective functions. To minimize energy consumption, heat pump is added on the basis of optimal heterogeneous azeotropic distillation and heat integration technology is used to further improve the energy recovery. The TAC, gas emission, energy consumption and exergy destruction are used to discuss the economy and environmental protection of processes. Among all the processes, the heat pump with higher preheating temperature (HPT) assisted HAD process by combining with heat integration (HAD-HPT-HI) has best performances on economic, environment, energy and exergy. Compared with conventional HAD process, the HAD-HPT-HI achieves the reductions of 52.17%, 68.86%, 65.87% and 65.46% on TAC, total energy consumption, gas emissions and exergy destruction, respectively.

Energy-Saving Investigation of Entrainer Enhanced Vacuum Reactive Distillation for Ethyl Acetate Production

An entrainer-assisted vacuum reactive distillation simulation is presented to synthesise high-purity ethyl acetate from acetic acid and ethanol. This process has the advantages of both heterogeneous azeotropic distillation and reactive distillation. Cyclohexane is used as an entrainer to break the water-ethanol azeotrope and extract water from the reactive part more efficiently. The feasibility of cyclohexane is evaluated using the residue curve map technique. The influence of various process parameters, such as reflux ratio, distillate to feed ratio, feed location of reactants and number of reactive stages on reboiler duty requirement, total annual cost, and purity of the product, were investigated. Comparison of EIARD and EIVRD configurations showed that EIVRD configuration showed 24.19% savings in reboiler duty per kg of product, 20% saving in total operating cost, and 6.59% saving in TAC.

Design and Optimization of Isopropyl Alcohol-Water Separation using Heterogenous Azeotropic Distillation

Heterogeneous azeotropic distillation is one technique of separating the mixtures that form azeotropes. In this research, a case study will be carried out on separating a mixture of isopropyl alcohol (IPA) and water where this mixture forms an azeotropic point. IPA is an alcohol that can be converted into diesel fuel through an esterification reaction. This study will use the Aspen Plus v8.8 simulator. The entrainer used were benzene and cyclohexane. The thermodynamic model used was NRTL. The configuration used in this study consists of two distillation columns with one decanter to separate the ternary azeotropic points. Optimization is carried out sequentially by changing one variable while the other variables are kept constant. The variables used are the number of stages, and the location of the feed entered in each column. The objective function used in this optimization is the Total Annual Cost (TAC). This research obtained a heterogeneous azeotropic distillation configuration that produced high-purity IPA and water products. Based on the optimization results, the benzene entrainer is cheaper than the cyclohexane entrainer.

Systematic Design and Evaluation of Energy-Efficient Alternatives of Heterogeneous Azeotropic Distillation: Furfural Case Study

Separation of azeotropic mixtures receives special attention for their impact on various significant industrial processes. Because of the non-ideal behaviour of these mixtures, it is impossible to separate them by conventional distillation. Instead of a single distillation unit, a system of multiple operations is to be employed. Heterogeneous azeotropic distillation (HAD) is an example of this kind of systems, where entrainers are applied to modify the behaviour of the mixture. The selection of the best separation system is a key objective during the synthesis of the process network. However, synthesis of HAD is especially difficult because of the complex interaction between its continuous and discrete features. Therefore, traditional separation network synthesis tools are incapable of solving this problem. In this work, the properties of the ternary vapor-liquid-liquid equilibrium diagram are exploited for systematically identifying plausible operating units that perform the separation of the azeotrope. Subsequently, energy consumption of the entire network is estimated through rigorous simulation. The P-graph framework is employed to represent the system’s structure. Additionally, its combinatorial algorithms generate a rigorous superstructure for the synthesis problem, and the set of n-best designs that minimize energy consumption. The method is illustrated by synthesizing the dehydration of furfural through HAD. The results demonstrate that it constitutes a valuable tool for the designer by being effective in the systematic identification and assessment of HAD alternatives.

Separation of the Mixture 2-Propanol + Water by Heterogeneous Azeotropic Distillation with Isooctane as an Entrainer

Advanced processes, which are alternatives to ordinary distillation, are essential to dehydrate azeotropic alcoholic mixtures for biofuel production. In that regard, this work focuses on the analysis of heterogeneous azeotropic distillation for the separation of a 2-propanol + water mixture in order to recover the alcohol with a sufficiently low water content. By comparing the performances of various entrainers on the basis of ternary maps, isooctane was selected for further process analysis. An advantage it poses is related to the fact that traces of it within the recovered dehydrated alcohol are highly welcome with a view to its subsequent use as a fuel. Aspen Plus® V11 software was employed for the simulation of the process, thus filling the gap existing in the literature due to the lack of studies on the process analysis of the heterogeneous azeotropic distillation of the 2-propanol + water system using isooctane as an entrainer.

Bioethanol dehydration and mixing by heterogeneous azeotropic distillation

Bioethanol is mixed with gasoline according to many countries' legislation pursuing environmental sustainability by reducing the use of fossil fuels. Bioethanol is produced by fermentation of many organic waste or biomass resources in diluted aqueous media. Unfortunately, bioethanol for fuel use must have a low content of water and its recovery is an energy intensive operation. Heterogeneous azeotropic distillation (HAD) is a well-known suitable option for dehydration of alcohols, e.g. ethanol. Many entrainers for this process are studied in literature and, in this study, is checked and verified that gasoline and gasoline additives present the lowest energy consumption. For this purpose, novel processes are proposed and rigorously simulated using AspenPlus® to verify their performance with respect to conventional processes used currently. Based on the simulation results, the processes are then compared in terms of environmental impact (expressed by the Potential Environmental Impact (PEI) index) and economic cost. Ethanol dehydration is a non-spontaneous process that requires energy to be accomplished and, on the other hand, mixing ethanol with gasoline and additives is a spontaneous process. Combining both processes in synergy in a single unit, energy consumption decreases by 50% and Potential Environmental Impact by 80%. Finally, the economic study indicated the benefits of employing the novel proposed scheme of one distillation column as CAPEX is reduced by 20% and the payback time to 1.5 years. Therefore, a novel viable process is proposed that greatly reduces the environmental impact of nowadays gasoline production.

Improved design of separation process for the recovery of cyclohexane and sec-butyl alcohol from wastewater

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%.

Energy-efficient heterogeneous azeotropic distillation coupling with pressure swing distillation for the separation of IPA/DIPE/Water mixture

Isopropyl alcohol/diisopropylether/water mixture is commonly produced in the IPA production process. Improvement of the separation of water-rich mixture is crucial to achieve green production of IPA. Conventional extractive distillation proposed in recent literature was reproduced by revised VLLE binary parameters to ensure the accuracy of simulation results. A newly proposed energy-efficient process is developed based on the idea of liquid-liquid separation coupling with pressure-swing distillation in this work. Thorough consideration in different distillation regions on the complex residue curve map and optimization of the process parameters using sequential iterative method lead to a simple configuration of separation process without needing of foreign component as entrainer. Further heat-integrated strategies are analyzed and implemented in the proposed system to ensure the good energy-efficiency of the process. The final heat-integrated novel design flowsheet can save up to 33.0% in total operating cost and 23.0% in total annual cost as compared to extractive-distillation system proposed in recent literature, showing the potential of this energy-efficient configuration applied on mixture with the most complicated residue curve map.