scholarly journals Comparison of extractive distillation flowsheets for methanol–tetrahydrofuran–water mixtures

2020 ◽  
Vol 15 (3) ◽  
pp. 21-30
Author(s):  
V. M. Raeva ◽  
A. M. Dubrovsky
Keyword(s):  
Energy Consumption ◽  
Software Package ◽  
Extractive Distillation ◽  
Ternary Mixtures ◽  
Extractive Agent ◽  
Water Separation ◽  
Distillation Columns ◽  
Distillation Flowsheets ◽  
Pharmaceutical Industries ◽  
Vapor Liquid

Objectives. Synthesis and comparative analysis of the extractive distillation flowsheets for aqueous mixtures of solvents utilized in pharmaceutical industries using the example of a methanol−tetrahydrofuran−water system with various compositions. The ternary system contains two minimally boiling azeotropes that exist in a vapor–liquid phase equilibrium. To evaluate the selective effect of glycerol, the phase equilibria of the methanol–tetrahydrofuran–water and methanol–tetrahydrofuran–water–glycerol systems at 101.32 kPa were studied.Methods. The calculations were carried out in the Aspen Plus V.9.0 software package. The vapor–liquid equilibria were simulated using the non-random two-liquid (NRTL) equation with the binary interaction parameters of the software package database. To account for the non-ideal behavior of the vapor phase, the Redlich–Kwong equation of state was used. The calculations of the extractive distillation schemes were carried out at 101.32 kPa.Results. The conceptual flowsheets of extractive distillation are proposed. The flowsheets consist of three (schemes I–III) or four (scheme IV) distillation columns operating at atmospheric pressure. In schemes I and II, the extractive distillation of the mixtures is carried out with tetrahydrofuran isolation occurring in the distillate stream. Further separation in the schemes differs in the order of glycerol isolation: in the third column for scheme I (traditional extractive distillation complex) or in the second column for scheme II (two-column extractive distillation complex + methanol/water separation column). Sсheme III caters to the complete dehydration of the basic ternary mixtures, followed by the extractive distillation of the azeotropic methanol–tetrahydrofuran system, also with glycerol. Sсheme IV includes a preconcentration column (for the partial removal of water) and a traditional extractive distillation complex.Conclusions. According to the criterion of least energy consumption for separation (the total load of the reboilers of distillation columns), sсheme I (a traditional complex of extractive distillation) is recommended. Additionally, the energy expended for the separation of the basic equimolar mixture using glycerol as the extractive agent was compared with that expended using another selective agent: 1,2-ethanediol. Glycerol is an effective extractive agent because it reduces energy consumption, in comparison with 1,2-ethanediol, by more than 5%.

scholarly journals ANALYSIS OF ENERGY CONSUMPTION OF EXTRACTIVE DISTILLATION FLOWSHEETS OF FOUR-COMPONENT SOLVENT MIXTURE

2021 ◽  
Vol 64 (6) ◽  
pp. 47-55
Author(s):  
Dmitry A. Ryzhkin ◽  
Valentina M. Raeva
Keyword(s):  
Energy Consumption ◽  
Total Energy ◽  
Dimethyl Sulfoxide ◽  
Extractive Distillation ◽  
Pressure Change ◽  
Total Energy Consumption ◽  
Water Separation ◽  
Selective Agents ◽  
Distillation Flowsheets ◽  
Pharmaceutical Industries

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.

scholarly journals SELECTION OF EXTRACTIVE AGENTS FOR THE SEPARATION OF CHLOROFORM - METHANOL - TETRAHYDROFURAN MIXTURE

2018 ◽  
Vol 13 (3) ◽  
pp. 30-40 ◽  
Author(s):  
V. M. Raeva ◽  
D. I. Sukhov
Keyword(s):  
Energy Consumption ◽  
Extractive Distillation ◽  
Industrial Test ◽  
Ideal Behavior ◽  
Component Mixture ◽  
Distillation Columns ◽  
Boiling Points ◽  
Derivative System ◽  
Separating Agents ◽  
Chloroform Methanol

Variants of the extractive distillation of chloroform - methanol - tetrahydrofuran equimolar mixture with industrial separating agents are considered. The basic system shows opposite deviations from the ideal behavior, because it contains binary azeotropes with minimum and maximum boiling points (3.3.1-4 system according to Serafimov’s classification). The choice of selective substances for extractive distillation was carried out taking into account the concentration dependences of the excess molar Gibbs energy of the binary constituents of the derivative system “chloroform - methanol - tetrahydrofuran - industrial test agent (ethylene glycol (EG), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (N-MP))” at 101.32 kPa. Based on the results of the evaluation of the thermodynamic criterion, DMSO and N-MP are recommended. Both agents show selective effect when separating two binary constituents. EG is selective only with respect to chloroform-tetrahydrofuran mixture. Since the tested agents show different selective effects, the final agent choice determines the qualitative composition of the product flows in the column for the extractive distillation of the three-component mixture (the first column of the flowsheet) and, accordingly, the structure of the total flowsheet. The schemes consist of two two-column complexes for extractive distillation (for the basic three-component mixture and for the binary mixture). The maximum contribution to the total reboiler energy consumption of the distillation columns is made by the first extractive distillation column: 65% (EG), 53% (N-MP) and 24% (DMSO). The use of the most selective agent reduces the energy consumption of this column: the reboiler load is maximal in the case of EG, in comparison with which the load is 47% lower in the case of N-MP and 76% lower in the case of DMSO.

scholarly journals SYNTHESIS OF FLOWSHEETS FOR SEPARATION OF MULTIPHASE MIXTURES: STATE OF THE ART

2018 ◽  
Vol 13 (3) ◽  
pp. 5-22 ◽  
Author(s):  
A. V. Frolkova ◽  
A. D. Merkulyeva ◽  
I. S. Gaganov
Keyword(s):  
Phase Separation ◽  
Energy Consumption ◽  
Butyl Acetate ◽  
Ternary Systems ◽  
Ternary Mixtures ◽  
Reflux Ratio ◽  
Total Energy Consumption ◽  
Separation Processes ◽  
Distillation Columns ◽  
Analytical Review

The paper presents an analysis of the current state of research on separation flowsheets based on the combination of distillation and phase separation processes, as well as heteroazeotropic distillation. It is shown that the works of foreign researchers devoted to the study of flowhseets with decanters are more focused on finding ways to reduce energy consumption by introducing additional separators, a combination of several methods (extractive and heteroazeotropic complex columns with external decanters. The task of synthesizing all possible separation flowsheets is not considered in these works. In this paper, a complete set of flowsheets of different structures based on the combination of distillation and phase separation processes, including the use of columns with an external decanter, is proposed for water - butyl acetate - methanol and methanol - heptane-water ternary mixtures separation. Aspen Plus and NRTL model were used for mathematical modelling of phase equilibrium (the relative error of describing liquid-vapor and liquid-liquid equilibrium is less than 5%) was chosen as a method of research. Operating parameters for distillation columns (the number of theoretical plates, feed plate, reflux ratio) and the total energy consumption were obtained for each case. The necessity of using a double feed-plate column for separating of propanol-1 - water - butanol-1 and ethyl acetate - water - butyl acetate ternary systems was explained by the presence of extractive effect. Analytical review of modern publications and results of own research allowed to formulate a number of recommendations for the synthesis of energy effective flowsheets based on a combination of distillation and phase separation processes.

Effect of Solvent Content on the Separation and the Energy Consumption of Extractive Distillation Columns

2014 ◽  
Vol 202 (9) ◽  
pp. 1191-1199 ◽  
Author(s):  
Marcella Feitosa De Figueiredo ◽  
Karoline Dantas Brito ◽  
Wagner Brandão Ramos ◽  
Luís Gonzaga Sales Vasconcelos ◽  
Romildo Pereira Brito
Keyword(s):  
Energy Consumption ◽  
Extractive Distillation ◽  
Distillation Columns ◽  
Solvent Content ◽  
Effect Of Solvent

scholarly journals Novel Hybrid Reactive Distillation with Extraction and Distillation Processes for Furfural Production from an Actual Xylose Solution

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1152
Author(s):  
Le Cao Nhien ◽  
Nguyen Van Duc Long ◽  
Moonyong Lee
Keyword(s):  
Production Process ◽  
Energy Use ◽  
Reactive Distillation ◽  
Process Efficiency ◽  
Continuous Stirred Tank Reactor ◽  
Butyl Chloride ◽  
Distillation Columns ◽  
Reactive Liquid ◽  
Pharmaceutical Industries ◽  
Furfural Production

Furfural is only derived from lignocellulosic biomass and is an important chemical used in the plastics, agrochemical, and pharmaceutical industries. The existing industrial furfural production process, involving reaction and purification steps, suffers from a low yield and intensive energy use. Hence, major improvements are needed to sustainably upgrade the furfural production process. In this study, the conventional furfural process based on a continuous stirred tank reactor and distillation columns was designed and optimized from an actual aqueous xylose solution via a biomass pretreatment step. Subsequently, a reactive distillation (RD) and extraction/distillation (ED) configuration was proposed for the reaction and purification steps, respectively, to improve the process efficiency. RD can remove furfural instantly from the reactive liquid phase and can separate heavy components from the raw furfural stream, while the ED configuration with toluene and butyl chloride used as extracting solvents can effectively separate furfural from a dilute aqueous stream. The results showed that the hybrid RD-ED process using a butyl chloride solvent saves up to 51.8% and 57.4% of the total investment costs and total annual costs, respectively, compared to the conventional process. Furthermore, environmental impacts were evaluated and compared for all structural alternatives.

Vapor-Liquid Equilibria for the Ternary System Ethyl Acetate-Acetonitrile-1-Octyl-3-Methylimidazolium Tetrafluoroborate

2013 ◽  
Vol 791-793 ◽  
pp. 141-144
Author(s):  
Xiu Min Shi ◽  
Min Wang
Keyword(s):  
Ionic Liquid ◽  
Ternary System ◽  
Ethyl Acetate ◽  
Mole Fraction ◽  
Salt Effect ◽  
Extractive Distillation ◽  
Relative Volatility ◽  
Azeotropic Point ◽  
Vapor Liquid Equilibria ◽  
Vapor Liquid

In order to research the possibility of separating the azeotrope of ethyl acetate + acetonitrile with ionic liquid as the extractant. Isobaric vapor-liquid equilibria for the ternary system ethyl acetate + acetonitrile + 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIBF4) were measured at 101.32 kPa using a recirculation still. The results showed that the VLE of the ternary system was different from that of the binary system. The ionic liquid (IL) studied showed a slight crossover salt effect, which changed the relative volatility of ethyl acetate to acetonitrile and eliminated the azeotropic point when the mole fraction of IL in the liquid phase was greater than 0.05. Therefore, [OMIBF4 can be used as the extractant of extractive distillation for ethyl acetate + acetonitrile system, the suitable mole fraction of [OMIBF4 is about 10%.

scholarly journals Separation processes for high purity ethanol production

2010 ◽  
Author(s):  
◽  
Peterson Thokozani Ngema
Keyword(s):  
Salt Concentration ◽  
High Purity ◽  
Alternative Fuels ◽  
Water System ◽  
Extractive Distillation ◽  
Operating Pressure ◽  
Extractive Agent ◽  
Relative Volatility ◽  
Vle Data ◽  
Feed Temperature

Globally there is renewed interest in the production of alternate fuels in the form of bioethanol and biodiesel. This is mainly due to the realization that crude oil stocks are limited hence the swing towards more renewable sources of energy. Bioethanol and biodiesel have received increasing attention as excellent alternative fuels and have virtually limitless potential for growth. One of the key processing challenges in the manufacturing of biofuels is the production of high purity products. As bioethanol is the part of biofuels, the main challenge facing bioethanol production is the separation of high purity ethanol. The separation of ethanol from water is difficult because of the existence of an azeotrope in the mixture. However, the separation of the ethanol/water azeotropic system could be achieved by the addition of a suitable solvent, which influences the activity coefficient, relative volatility, flux and the separation factor or by physical separation based on molecular size. In this study, two methods of high purity ethanol separation are investigated: extractive distillation and pervaporation. The objective of this project was to optimize and compare the performance of pervaporation and extraction distillation in order to produce high purity ethanol. The scopes of the investigation include:  Study of effect of various parameters (i) operating pressure, (ii) operating temperature, and (iii) feed composition on the separation of ethanol-water system using pervaporation.  Study the effect of using salt as a separating agent and the operating pressure in the extractive distillation process. The pervaporation unit using a composite flat sheet membrane (hydrophilic membrane) produced a high purity ethanol, and also achieved an increase in water flux with increasing pressure and feed temperature. The pervaporation unit facilitated separation beyond the ethanol – water system azeotropic point. It is concluded that varying the feed temperature and the operating pressure, the performance of the pervaporation membrane can be optimised. v The extractive distillation study using salt as an extractive agent was performed using the low pressure vapour-liquid equilibrium (LPVLE) still, which was developed by (Raal and Mühlbauer, 1998) and later modified by (Joseph et al. 2001). The VLE study indicated an increase in relative volatility with increase in salt concentration and increase in pressure operating pressure. Salt concentration at 0.2 g/ml and 0.3 g/ml showed complete elimination of the azeotrope in ethanol-water system. The experimental VLE data were regressed using the combined method and Gibbs excess energy models, particular Wilson and NRTL. Both models have shown the best fit for the ethanol/water system with average absolute deviation (AAD) below 0.005. The VLE data were subjected to consistency test and according to the Point test, were of high consistency with average absolute deviations between experimental and calculated vapour composition below 0.005. Both extractive distillation using salt as an extractive agent and pervaporation are potential technologies that could be utilized for the production of high purity ethanol in boiethanol-production.

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