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.

QSPR modeling of azeotropic temperatures and compositions for binary azeotropes containing lower alcohols using a genetic function approximation

Binary azeotropes, which contain two chemicals with a relative volatility of 1, are very common in the chemical industry. Understanding azeotropes is essential for effectively separating binary azeotropes containing lower alcohols. Experimental techniques and ab initio approaches can produce accurate results;however, these two processes are time consuming and labor intensive. Although thermodynamic equations such as UNIFAC are widely used, experimental values are required, and it is difficult to choose the best groups to represent a complex system. Because of their high efficiency and fast calculation speed, quantitative structure–property relationship(QSPR) tools were used in this work to predict the azeotropic temperatures and compositions of binary azeotropes containing lower alcohols. The QSPR models for 64 binary azeotropes based on centroid approximation and weighted-contribution-factor approximation were established using the genetic function approximation(GFA) procedure in Materials Studio software, and a leave-one-out cross-validation procedure was conducted.External tests of an additional 16 azeotropes were also investigated, and high determination coefficient values were obtained. The best QSPR models were explained in terms of the molecular structure of the azeotropes,and good predictive ability was obtained within acceptable prediction error levels.

PREPARATION OF NANOMETER ZrO_2-8% Y_2O_3 POWDERS BY AZEOTROPIC DISTILLATION PROCESSING

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Preparation and Characterization of La_(0.8)Sr_(0.2)MnO_(3-δ) Cathode for SOFCs Fabricated Using Azeotropic Distillation Method

Strontium doped lanthanum manganite (LSM) powders were synthesized by three different routes: azeotropic distillation, sol-gel and solid state reaction respectively. The LSM samples, made by azeotropic distillation and sol-gel methods were prepared by firing at 1000 ℃ for 6 h, and the LSM sample, made by solid state reaction method was produced by sintering at 1400 ℃ for 18 h. The samples were characterized by XRD, TEC, SEM, EIS and polarization performance analysis. The results show that all the samples made by different methods have pure orthorhombic LSM phase, however exhibit different micro structure and electrochemical characterization, which relates to the different synthesis methods. The solid state reaction method produces the samples with larger particle size compared with azeotropic distillation and sol-gel methods. The powders made by azeotropic distillation method have less agglomerated particles compared with that made by sol-gel method because the precursor in the former is dispersed in n-butanol before sintering. The polarization current density of powder made by azeotropic distillation method was twice of that made by sol-gel method and four times of that made by solid state reaction method. The values of polarization resistance (Rp) are 0.35 Ω·cm2 for the cathode synthesized by azeotropic distillation route, which is much lower than sol-gel (1.5 Ω·cm2) and solid state reaction (2.3 Ω·cm2) at 800 ℃.

Research Progress on Azeotropic Distillation Technology

Azeotropic distillation is a special distillation method for separating liquid mixtures, which has better distillation effect and obvious advantages of energy saving and consumption reduction compared with traditional distillation. In this paper, the latest research progress of azeotropic distillation technology in separation, synthesis and energy saving at home and abroad is reviewed. The research progress in separation is reflected in product separation and product purification, and the research progress in energy saving is reflected in heat pump distillation and dividing wall column distillation respectively. Existing studies have shown that azeotropic distillation technology can produce higher purity target products than conventional distillation for the separation and purification of azeotropic or near-boiling compounds. Heat pump distillation and dividing wall column distillation are used in azeotropic distillation field, resulting in obvious energy-saving effect for distillation equipment. The follow-up research direction of new separation technology with the goal of reducing energy consumption and exploring new materials as entraining agents should be studied in detail, which provides certain guidance for the development of distillation technology in China’s chemical industry.

Azeotropic mixture used for development and validation of Lornoxicam in bulk and its tablet dosage form by spectrophotometric method

A novel, safe, economic and sensitive method of spectrophotometric estimation has been developed using Azeoptropic mixture (water:methanol: 60:40, v/v) for the quantitative determination of Lornoxicam, a practically water-insoluble drug. Hence, Lornoxicam stock solution was prepared in Azeoptropic mixture. Lornoxicam showed maximum absorbance at 383 nm. Beer's law was obeyed in the concentration range 4-24 mg/mL with regression coefficient of 0.999. The method was validated in terms of linearity (R 2 0.999), precision (CV for intra-day and inter-day was 0.280.68 and 0.12-0.92, respectively), accuracy (98.03-100.59% w/w) and specificity. This method is simple, precise, accurate, sensitive and reproducible and can be used for the routine quality control testing of the marketed formulations.

Approach of Obtaining Liquor Flavoring From Yellow Water Based on Azeotropic Distillation

In order to extract the scarce natural liquor flavoring which is the dream of many liquor factories from yellow water,this research first added a proper amount of food-grade entrainer ethanol into yellow water,to form yellow water containing high content of ethanol.Then,the yellow water was subjected to azeotropic distillation and catalytic esterification,obtaining natural acetaldehyde,ethyl formate,ethyl acetate and esterification liquid containing various compounds that can influence the flavor of liquor.In the esterification liquid,the contents of ethyl propionate,ethyl butyrate,ethyl valerate,ethyl lactate and ethyl hexanoate are as higher as 19.0,46.5,1.5,39.8 and 137.1 g/L,respectively.The esterification liquid prepared by one fraction of yellow water can blend 9.14 fractions of common liquor into top-grade Luzhou-flavor liquor.Therefore,yellow water has great recycling value.

Effects of imidazolium-based ionic liquids on the isobaric vapor–liquid equilibria of methanol+dimethyl carbonate azeotropic systems

The separation of methanol(MeOH)and dimethyl carbonate(DMC)is important but difficult due to the formation of an azeotropic mixture.In this work,isobaric vapor–liquid equilibrium(VLE)data for the ternary systems containing different imidazolium–based ionic liquids(ILs),i.e.MeOH+DMC+1-butyl-3-methy-limidazolium bis[(trifluoromethyl)sulfonyl]imide([Bmim][Tf2N]),MeOH+DMC+1-ethyl-3-methyl-imidazolium bis[(trifluoromethyl)sulfonyl]imide([Emim][Tf2N]),and MeOH+DMC+1-ethyl-3-methylimidazolium hexafluorophosphate([Emim][PF6])were measured at 101.3 kPa.The mole fraction of IL was varied from0.05 to 0.20.The experimental data were correlated with the NRTL and Wilson equations,respectively.The results show that imidazolium-based ILs were beneficial to improve the relative volatility of MeOH to DMC,and[Bmim][Tf2 N]showed a much more excellent performance on the activity coefficient of MeOH.The interaction energies of system components were calculated using Gaussian program,and the effects of cation and anion on the separation coefficient of the azeotropic system were discussed.

Molecular interaction mechanism in the separation of a binary azeotropic system by extractive distillation with ionic liquid

Ionic liquids(ILs)have shown excellent performance in the separation of binary azeotropes through extractive distillation[1].But the role of the ionic liquid in azeotropic system is not well understood.In this paper,COSMO-RS model was applied to screen an appropriate IL to separate the binary azeotrope of ethyl acetate(EA)and ethanol and 1-octyl-3-methylimidazolium tetrafluoroborate([OMIM][BF4])was selected.The Quantum Mechanics(QM)calculations and molecular dynamics(MD)simulation are performed to study the interactions between the solvent molecules and[OMIM][BF4],in order to investigate the separation mechanism at the molecular level.The nature of the interactions is studied through the reduced density gradient(RDG)function and quantum theory of Atom in Molecule(QTAIM).Hydrogen bonds and van der Waals interactions are the key interactions in the complexes.The results of MD simulations indicate that the introduction of ILs has a prominent effect on the interaction between the solvent molecules,especially on reducing the number of hydrogen bonds among the solvent molecules.The radial distribution function(RDF)reveals that the interaction between the cation and solvent molecules will increase while the concentration of ILs increases.This paper provides important information for understanding the role of ILs in the separation of the azeotropic system,which is valuable to the development of new entrainers.

Separation of isopropyl alcohol+isopropyl acetate azeotropic mixture:Selection of ionic liquids as entrainers and vapor-liquid equilibrium validation

Based on the COSMO-SAC model,1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium p-toluenesulfonate were selected from 30 ILs as entrainers to investigate the separation of the isopropyl alcohol+isopropyl acetate azeotrope.Two screening indicators,σ-profile and infinite dilution selectivity(S^(∞)),were adopted as the basis.The iso baric vapor-liquid equilibrium experiments for isopropyl alcohol+isopropyl acetate binary system and isopropyl alcohol+isopropyl acetate+confirmed ILs ternary systems were performed at the pressure of atmospheric pressure.The experimental measurement demonstrated that the adopt ILs enhanced the relative volatility of the above alcohol-ester azeotrope,leading to the elimination of the azeotropic point with a certain amount ILs.Meanwhile,the thermodynamic correlation for two systems containing ILs was explored with the NRTL model,which also reflects the extensive applicability of that by comparing the deviation between experimental and calculated data.And its binary interaction parameters were regressed,which can provide a basis for its simulation process.

Economy, environmental assessment and energy conservation for separation of isopropanol/diisopropyl ether/water multi-azeotropes via extractive distillation coupled pervaporation process

This wok proposed the extraction distillation coupled pervaporation(ED+PV) technology process using two different solvents to separate isopropanol(IPA) and diisopropyl ether(DIPE) from DIPE/IPA/H_(2)O ternary heterogeneous azeotropes in industrial wastewater from the synthesis of isopropanol in this study.Based on strict design specifications, simulation and sequential iteration methods are used for process design and optimization. Compared to the ethylene glycol(EG)-EG+H_(2)O process and the 1,3-propanediol(PDO)-IPA+H_(2)O process, the total annual cost(TAC) of the EG-IPA+H_(2)O process decreased by 20.76% and 7.86%(PDO). Compared to the EG-EG+H_(2)O process, the TAC of the PDO-IPA+H_(2)O process reduced 14%, but the global warming potential(GWP) and human toxicity of the PDO-IPA+H_(2)O process increased 11.3% and 4.07% respectively. Compared to the PDO-IPA+H_(2)O process, the EG-IPA+H_(2)O process saves 7.86%(TAC), 9.78%(GWP) and 9.85%(human toxicity). The ED+PV process with EG is superior to PDO in factors of TAC, energy consumption, human toxicity and environment. The EG-IPA+H_(2)O process changed the separation order of the products of the multi-azeotropic system, reduced the cost and energy conservation of the system, and enhanced the environmental protection evaluation of the process, is the best process through life cycle assessment for analyzing the economy, energy conservation, environmental assessment and human toxicity, designing cleaner products, controlling waste discharge, and promoting the chemical purification industry. This work provides a new process design and optimized separation ideas, will have a good guiding significance for the research and application separation of multi-azeotropic mixture with mixed solvents in organic wastewater from the cleaner chemical production, has been up to standard wastewater discharge process, and realized the development goal of carbon peak and carbon neutrality in the sustainable development of chemical clean industry.

Separation of fuel additives based on mechanism analysis and thermodynamic phase behavior

tert-butanol and ethyl acetate,as fuel additives and oxygenated fuels,can improve fuels quality and reduce exhaust emissions.Therefore,the recovery of these compounds from azeotropic systems is of great significance.Ionic liquids(ILs)are promising green solvents for separating azeotropic systems.In this study,an efficient extraction strategy based on 1-butyl-3-methylimidazolium acetate([Bmim][AC])is proposed.The mechanism by which ILs enable the separation of binary alcohol-ester azeotropes was revealed by evaluating the lowest conformational energy through combining an independent gradient model based on the Hirshfeld partition(IGMH)and frontier molecular orbitals,to preliminarily screen the extractants.The range of extractants was further reduced by a vapor–liquid phase equilibrium(VLE)experiment,and a modeling method for separating the alcohol–ester system and recovering the solvent using[Bmim][AC]and 1-ethyl-3-methyl-3-imidazolium acetate([Emim][AC])is established.Under the optimal operating conditions,the use of[Bmim][AC]can reduce the total annual cost(TAC)per year by 17.78%,and the emissions of CO_(2),SO_(2),and NO can be reduced by 10.86%.In this study,a comprehensive method for screening extractants is proposed,and the simulation process is optimized in combination with the economic and environmental impact.The results have important guiding significance for realizing efficient,energy-saving,and green azeotropic separation systems in industry.

Preparation of Liquor Flavoring from Yellow Water Based on Water Absorbent Resin

[Objective] This study was conducted to extract the scarce natural liquor flavorings desired by many liquor factories from yellow water. [Method]Strong water absorbent resin was used to absorb moisture from the yellow water in order to concentrate it into dense yellow water at first,followed by azeotropic distillation of the previously concentrated yellow water,and then,catalytic esterification was performed to the remaining liquid after the distillation. [Results] The 7. 066 7 fractions of concentrated yellow water with 56. 7% ethanol could be obtained after the treatment of 100 fractions of yellow water with strong water absorbent resin. Azeotrope of 0. 432 8 fraction of natural acetaldehyde,0. 269 4 fraction of ethyl formate and methyl alcohol,0. 975 0 fraction of ethyl acetate and methyl alcohol could be obtained after the azeotropic distillation per 100 fractions of concentrated yellow water. After the addition of CaCl_2,0. 220 7 fraction of ethyl formate and 0. 514 2 fraction of ethyl acetate could be obtained after distillation of the azeotrope. Finally,92. 094 8 fractions of esterification liquid with 38 kinds of flavoring compound could be obtained after catalytic esterification of 100 fractions of concentrated yellow water,and the content of ethyl acetate,ethyl propionate,ethylbutyrate,ethyl valerate,ethyl lactate and ethyl hexanoate were as much as 142. 9,22. 2,54. 2,3. 3,75. 4 and 158. 9 g/L,respectively. [Conclusion]Top-grade Luzhou-flavor liquor could be made by mixing 6. 5 fractions of common liquor with acetaldehyde,ethyl formate,ethyl acetate and esterification liquid which were obtained from 1 fraction of yellow water. Therefore,the yellow water has a great recycling value,and it tells us that the technique of extracting liquor flavorings from yellow water has tremendous market value.

Study on Separation of Toluene and Hexamethyl-disiloxane from Cephalosporin Waste

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Determination of Tritium Concentration in Heavy Water

In this work, tritium concentration was determined in different D2O enrichment in heavy water samples. Samples were prepared from Arak Heavy Water Production Plant. Tritium concentration was determined utilizing liquid scintillation detector (LSC) system based on β-decay of tritium isotope. In this work instead of simple distillation, the azeotropic distillation method was used. Absorbed spectra and fluorescence spectra were registered by Shimadz spectrometer UV-2100 model and fluorescence spectrometer LS50B model respectively. Tritium concentration was obtained from 1.75 ± 0.80 up 6.16 ± 1.01 Bq/L for 0.35% to 77.50% enrichment of D2O concentration in heavy water samples. Coefficient correlation between tritium concentration and D2O concentration in heavy water R2 = 0.853 was derived. For 99.8% enriched D2O in heavy water, deviation was observed from direct line that caused decreasing of R2.

Effect of Two Liquid Phases on the Separation Efficiency of Distillation Columns

Distillation is one of the oldest and most important separation processes used in the chemical and petrochemical industries. On the other hand, it is a process the thermodynamic efficiency of which is very low, and therefore reducing the consumption of energy is one of the targets of research studies on distillation. This article arose from seeking to reduce energy consumption in a distillation train of 1,2-dichloroethane (ethylene dichloride-EDC) of a commercial plant producing vinyl monochloride (VMC), which involves an azeotropic distillation column. The reduction in the reboiler heat duty caused significant changes in concentration and temperature profiles throughout the column due to the formation of two liquid phases. The results show that, although very small in percentage terms (less than 2.5%), the appearance of the 2nd liquid phase causes significant changes in the operation of the column and the separation achieved.

Extractive Distillation of Methyl Acetate-Methanol Azeotrope Using [DMIM]DMP as Solvent

In order to separate methyl acetate and methanol azeotrope, the ionic liquid(IL) 1,3-dimethylimidazolium dimethylphosphate([DMIM]DMP) was used as the solvent. The Aspen Plus software was used to design and optimize the extractive distillation process. Under the optimized conditions, the mass fractions of methyl acetate and methanol were both above 99.5%. Compared with the dimethyl sulfoxide(DMSO) process, the [DMIM]DMP process has the advantages of saving energy and lower equipment investment cost. The result shows that using [DMIM]DMP as the solvent to separate a methyl acetate and methanol azeotrope has better prospect in industrial application.

Application of the Chemical-Looping Concept for Azoetrope Separation

The need for the separation of azeotropic mixtures for the production of high-end chemicals and resource recovery has spurred significant research into the development of new separation methods in the chemical industry.In this paper,a green and sustainable method for azeotrope separation is proposed based on a chemical-looping concept with the help of reversible-reaction-assisted distillation.The central concept in the chemical-looping separation(CLS)method is the selection of a reactant that can react with the azeotrope components and can also be recycled by the reverse reaction to close the loop and achieve cyclic azeotrope separation.This paper aims to provide an informative perspective on the fundamental theory and applications of the CLS method based on the separation principle,reactant selection,and case analysis,for example,the separation of alkenes,alkane,aromatics,and polyol products.In summary,we provide guidance and references for chemical separation process intensification in product refining and separation from azeotropic systems for the development of a more sustainable chemical industry.

Design and control of fraction cutting for the separation of mixed alcohols from the Fischer-Tropsch aqueous by-products

Since the minimum-boiling azeotropes of C2-C8 alcohols with water and high-water content(up to 95%(mass))in the Fischer-Tropsch aqueous by-products,the separation is energy-intensive and challenging.The energy-saving strategy for the complete separation of the Fischer-Tropsch aqueous by-products has received massive attention in recent decades.In this study,a stripper-sidestream decanter process is proposed by exploiting homogeneous azeotropes(C2-C3 alcohols-water)and heterogeneous azeotropes(C4-C8 alcohols-water).The introduction of the stripping column for pre-dehydration avoids the revaporization of the mixture,and energy carried by the overhead vapor is conserved instead of being removed in a condenser.The precise fraction cutting of C1-C3 alcohol-water mixture,C4-C8 alcohols,and water is realized by the sidestream distillation column.The C4-C8 alcohols rich mixture withdrawn from the sidestream flows into the decanter to break the distillation boundary,where the organic phase returns to the sidestream distillation column to obtain the dehydrated C4-C8 alcohols,and the aqueous phase enters the stripping column.Steady-state optimization based on total annual cost(TAC)minimization shows that the stripper-sidestream decanter process reduces TAC by 17.00%and saves energy by 21.27%compared with the conventional three-column distillation process.Further,a control structure of the process is established,and dynamic simulations show that the control structure combining a differential controller with a low-selector exhibits robust co ntrol.This study provides a novel design scheme and deepens the insights into the efficient separation of aqueous by-products of the Fischer-Tropsch synthesis.

Dynamic control analysis of interconnected pressure-swing distillation process with and without heat integration for separating azeotrope

Dynamic controls of pressure-swing distillation with an intermediate connection(PSDIC) process of ethyl acetate and ethanol separation were investigated.The double temperature/composition cascade control structure can perfectly implement effective control when ±20% feed disturbances were introduced.This control structure did not require the control of the flowrate of the side stream.The dynamic controllability of PSDIC with partial heat integration(PHIPSDIC) was also explored.The improved control structure can effectively control ±20% feed disturbances.However,in industrial production,simple controller,sensitive and easy to operate,is the optimal target.To avoid the use of component controllers or complex control structure,the original product purities could be maintained using the basic control structure for the PSDIC process if the product purities in steady state were properly increased,albeit by incurring a slight rise in the total annual cost(TAC).This alternative method without a composition controller combined with the energy-saving PSDIC process provides a simple and effective control scheme in industrial production.