In this work,the ternary azeotrope of tert-butyl alcohol/ethyl acetate/water is separated by extractive distillation(ED)to recover the available constituents and protect the environment.Based on the conductor like shi...In this work,the ternary azeotrope of tert-butyl alcohol/ethyl acetate/water is separated by extractive distillation(ED)to recover the available constituents and protect the environment.Based on the conductor like shielding model and relative volatility method,ethylene glycol was selected as the extractant in the separation process.In addition,in view of the characteristic that the relative volatility between components changes with pressure,the multi-objective optimization method based on nondominated sorting genetic algorithm II optimizes the pressure and the amount of solvent cooperatively to avoid falling into the optimal local solution.Based on the optimal process parameters,the proposed heat-integrated process can reduce the gas emissions by 29.30%.The heat-integrated ED,further coupled with the pervaporation process,can reduce gas emission by 42.36%and has the highest exergy efficiency of 47.56%.In addition,based on the heat-integrated process,the proposed two heat pump assisted heat-integrated ED processes show good economic and environmental performance.The double heat pump assisted heat-integrated ED can reduce the total annual cost by 28.78%and the gas emissions by 55.83%compared with the basis process,which has a good application prospect.This work provides a feasible approach for the separation of ternary azeotropes.展开更多
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 heteroge...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.展开更多
Extractive distillation(ED)and solvent-assisted pressure-swing distillation(SA-PSD)are both special distillation processes that perform good at separating pressure-insensitive azeotropes.However,few reported studies h...Extractive distillation(ED)and solvent-assisted pressure-swing distillation(SA-PSD)are both special distillation processes that perform good at separating pressure-insensitive azeotropes.However,few reported studies have compared the performance of the two processes.In this paper,ED processes with N-methylpyrrolidone(NMP)and dimethlac-etamide(DMCA)as entrainer,SA-PSD process with isopropyl-alcohol(IPA)as solvent and SA-PSD process with partial heat integration(PHI-PSD)are proposed to achieve high purity separation of a mixture of cyclohexane/2-butanol system.The optimal operating conditions of the processes are obtained after optimizing with NSGA-Ⅱ algorithm when total annual cost(TAC)and the entropy production of process are set as objectives.The optimal results show that the optimal PHI-PSD process has lower TAC by 28.7% and the lower entropy production by 39.5% than the optimal SA-PSD process while the ED process with NMP as entrainer has lower TAC by 50.9% and the lower entropy production by 56.1% than the optimal SA-PSD process.The optimal results show that the ED process with NMP as entrainer has the best economic and thermodynamic efficiency among the four proposed processes in this paper.展开更多
The benzene and acetonitrile azeotropic mixture was proposed to be separated by extractive distillation using an ionic liquid(IL)as the entrainer.The suitable IL was selected by the COSMO-RS model,and 1-ethyl-3-methyl...The benzene and acetonitrile azeotropic mixture was proposed to be separated by extractive distillation using an ionic liquid(IL)as the entrainer.The suitable IL was selected by the COSMO-RS model,and 1-ethyl-3-methylimidazolium tetrafluoroborate([EMIM][BF_(4)])was considered as the suitable entrainer mainly due to its high selectivity,low viscosity,and low price.The experimental vapor pressure data of the IL-containing systems(benzene+[EMIM][BF_(4)]and acetonitrile+[EMIM][BF_(4)])were measured in the full concentration range.The results show that acetonitrile has a stronger interaction with IL than benzene,and the low deviations between the experimental and UNIFAC predicted values show the reliability of the UNFIAC model.The UNIFAC predicted vapor-liquid equilibrium data of the benzene+acetonitrile+dimethyl sulfoxide(DMSO)/[EMIM][BF_(4)]system show that the relative volatility of benzene to acetonitrile is higher when the entrainer is[EMIM][BF_(4)].The process simulation results show that[EMIM][BF_(4)]can reduce the material and energy consumptions compared with DMSO.展开更多
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,C...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.展开更多
The ionic liquid(IL)1-ethyl-3-methylimidazolium dicyanamide([EMIM][DCA])was selected as an appropriate entrainer for the extractive distillation of the methanol-ethanol-water mixture.The COSMO-RS model was applied to ...The ionic liquid(IL)1-ethyl-3-methylimidazolium dicyanamide([EMIM][DCA])was selected as an appropriate entrainer for the extractive distillation of the methanol-ethanol-water mixture.The COSMO-RS model was applied to screen out the appropriate solvents considering selectivity and solvent capacity together.Isobaric vapor-liquid equilibrium(VLE)experiments for the two systems of methanol-water and ethanol-water with different amounts of[EMIM][DCA]added were conducted at 101.3 kPa.The experimental data showed that[EMIM][DCA]exhibits an obvious salting effect for the methanol(or ethanol)-water mixture and eliminates the azeotropic point of ethanol-water.Moreover,the predicted values by UNIFAC-Lei model coincide well with experimental data.The separation mechanism was further explained in combination with surface charge density distribution(σ-profiles),excess enthalpy(HE),and binding energy.In addition,the flow charts were designed to evaluate the improvement of energy consumption with[EMIM][DCA]as the entrainer when compared to ethylene glycol(EG).The simulation results demonstrated that[EMIM][DCA]is more energy efficient than EG.展开更多
Economically separating 1-propanol(NPA)from water is an emergent issue for producing pharmaceutical intermediates such as n-propyl acetate,n-propylamine and so on.In this work,fourionic liquids(ILs)1-ethyl-3-methylimi...Economically separating 1-propanol(NPA)from water is an emergent issue for producing pharmaceutical intermediates such as n-propyl acetate,n-propylamine and so on.In this work,fourionic liquids(ILs)1-ethyl-3-methylimidazolium thiocyanate([EMIM][SCN]),1-butyl-3-methylimidazolium tetrafluoroborate([BMIM][BF_(4)]),1,3-dimethylimidazolium methylsulfate([MMIM][MS]),1,3-dimethylimidazolium dimethylphosphate([MMIM][DMP])were introduced as potential entrainers for separating NPA–water azeotropic mixture.The results show that[MMIM][MS]is the most suitable entrainer compared with other ILs from the analysis of vapor-liquid equilibrium and relative volatilities.The extractive distillation process with the entrainer regeneration system of flash tank and stripper was employed and optimized by the two-step optimization method.The results show that total annual cost and energy consumption per product flow rate were reduced by 39.79%and 60.47%compared with literature.In addition,the efficiency indicator of extractive section,efficiency indicator of per tray in extractive section,carbon dioxide emissions were also selected as the evaluation index for selection of operating parameters and calculated for different cases.The CO_(2)emissions of the optimal design can be reduced by 60.98%from environmental aspect.展开更多
In the present work,a comparative study of the extractive distillation and pressure swing distillation for methanol-acetonitrile separation is performed for the first time.Different separation alternatives,including t...In the present work,a comparative study of the extractive distillation and pressure swing distillation for methanol-acetonitrile separation is performed for the first time.Different separation alternatives,including the conventional extractive distillation,the extractive distillation with vapor or liquid side-stream,the pressure-swing distillation with or without full heat integration,and the heat-pump assisted pressure-swing distillation are rigorously simulated and optimized based on the minimum total annual cost(TAC)via the sequential iterative strategy.The results show that TAC and CO2 emission of the new extractive distillation with vapor side-stream(Vapor-SED)are similar to those of the extractive distillation with liquid side-stream(Liquid-SED).Furthermore,the Vapor-SED and Liquid-SED can achieve 30.01%and 30.56%reduction in TAC and 23.32%and 23.49%reduction in CO2 emission,respectively,over the most competitive fully heat-integrated PSD configuration.Hence,the extractive distillation with vapor or liquid side-stream appears to be a better option economically and environmentally for the separation of methanol and acetonitrile.展开更多
To analyze the chemical constituents of volatile oils from the fruit of Periploca forrestii Schltr.which were collected in Guizhou province.This volatile oils were extracted by simultaneous distillation extraction (SD...To analyze the chemical constituents of volatile oils from the fruit of Periploca forrestii Schltr.which were collected in Guizhou province.This volatile oils were extracted by simultaneous distillation extraction (SDE)and microwave assistant extraction(MAE) method,and ananlyzed by gas chromatography-mass spectrometry(GC-MS)method.The main chemical compounds were methyl salicylate,β-amyrin and β-amyrin acetate etc.The compounds from the volatile oils extracted with SDE and MAE are quite different.The results provide scientific proof for the further development and utilization of Periploca forrestii Schltr.展开更多
It is difficult to separate the methanol and hydrocarbons in the propylene oxide(PO)purification process due to their forming azeotrope.As for this,a novel PO separation process,in that the deionized water is employed...It is difficult to separate the methanol and hydrocarbons in the propylene oxide(PO)purification process due to their forming azeotrope.As for this,a novel PO separation process,in that the deionized water is employed as extractant and 1,2-propylene glycol(MPG)that is formed from the PO hydrolysis reaction is recovered,is presented in this work.The salient feature of this process is that both the non-catalyzed reactions of PO hydrolysis to form MPG and dipropylene glycol(DPG)are simultaneously considered and MPG by-product with high purity is obtained in virtue of the deionized water as reflux liquid and side take-off in MPG column.In addition,the ionic liquid(IL)extractant is screened through the conductorlike screening model for segment activity coefficient(COSMO-SAC)and the comparisons of separation efficiency between the IL and normal octane(nC_(8))extractant for the separation of PO and 2-methylpentane are made.With the non-random two-liquid(NRTL)thermodynamic model,the simulation and optimization design for the full flow sheet are performed and the effects of the key operation parameters such as solvent ratio,theoretical stages,feeding stage etc.on separation efficiency are detailedly discussed.The results show that the mass purity and the mass yield of PO can be up to 99.99%and 99.0%,and the condenser duty,reboiler duty and PO loss in the process with IL extractant can be decreased by 69.66%,30.21%and 78.86%compared to ones with nC_(8).The total annual cost(TAC)calculation also suggests that the TAC would be significantly reduced if using IL in replace of nC_(8) for the investigated process.The presented results would provide a useful guide for improving the quality of PO product and the economic efficiency of industrial plant.展开更多
In the traditional extractive distillation process,organic solvents are often used as entrainers.However,environmental influence and high energy-consumption are significant problems in industrial application.In this s...In the traditional extractive distillation process,organic solvents are often used as entrainers.However,environmental influence and high energy-consumption are significant problems in industrial application.In this study,a systematic screening strategy and innovative energy-saving design for ionic liquid-based extractive distillation process was proposed.The innovative energy-saving design focused on the binary minimum azeotrope mixtures isopropanol and water.Miscibility,environmental impact and physical properties(e.g.,melting point and viscosity)of 30 ionic liquids were investigated.1-Ethyl-3-methyl-imidazolium dicyanamide and 1-butyl-3-methyl-imidazolium dicyanamide were selected as candidate entrainers.Feasibility analysis of these two ionic liquids was further performed via residue curve maps,isovolatility line and temperature profiles.An innovative ionic liquid-based extractive distillation process combining distillation column and stripping column was designed and optimized with the objective function of minimizing the total annualized cost.The results demonstrate that the total annualized cost was reduced by 19.9%with 1-ethyl-3-methyl-imidazolium dicyanamide as the entrainer and by 24.3%with 1-butyl-3-methyl-imidazolium dicyanamide,compared with that of dimethyl sulfoxide.The method proposed in this study is conducive to the green and sustainable development of extractive distillation process.展开更多
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 p...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.展开更多
The traditional approach to solvent selction in the extractive distillation process strictly focuses on the change in the relative voltility of light-heavy components induced by the solvent.However,the total annual co...The traditional approach to solvent selction in the extractive distillation process strictly focuses on the change in the relative voltility of light-heavy components induced by the solvent.However,the total annual cost of the process may not be minimal when the solvent induces the largest change in relative volatility.This work presents a heuristic method for selecting the optimal solvent to minimize the total annual cost.The functional relationship between the relative volatility and the total annual cost is established,where the main factors,such as the relative volatility of the light-heavy components and the relative volatility of the heavy-component solvent,are taken into account.Binary azeotropic mixtures of methanol-toluene and methanol-acetone are separated to verify the feasibility of the model.The results show that using the solvent with the minimal two-column extractive distillation index,the process achieves a minimal total annual cost.The method is conducive for sustainable advancements in chemistry and engineering because a suitable solvent can be selected without simulation verification.展开更多
基金supported by the National Natural Science Foundation of China(22178188).
文摘In this work,the ternary azeotrope of tert-butyl alcohol/ethyl acetate/water is separated by extractive distillation(ED)to recover the available constituents and protect the environment.Based on the conductor like shielding model and relative volatility method,ethylene glycol was selected as the extractant in the separation process.In addition,in view of the characteristic that the relative volatility between components changes with pressure,the multi-objective optimization method based on nondominated sorting genetic algorithm II optimizes the pressure and the amount of solvent cooperatively to avoid falling into the optimal local solution.Based on the optimal process parameters,the proposed heat-integrated process can reduce the gas emissions by 29.30%.The heat-integrated ED,further coupled with the pervaporation process,can reduce gas emission by 42.36%and has the highest exergy efficiency of 47.56%.In addition,based on the heat-integrated process,the proposed two heat pump assisted heat-integrated ED processes show good economic and environmental performance.The double heat pump assisted heat-integrated ED can reduce the total annual cost by 28.78%and the gas emissions by 55.83%compared with the basis process,which has a good application prospect.This work provides a feasible approach for the separation of ternary azeotropes.
基金supported by the National Natural Science Foundation of China (21776145 and 21808117)。
文摘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.
基金supported by the National Natural Science Foundation of China(22178030,21878025,22078026)。
文摘Extractive distillation(ED)and solvent-assisted pressure-swing distillation(SA-PSD)are both special distillation processes that perform good at separating pressure-insensitive azeotropes.However,few reported studies have compared the performance of the two processes.In this paper,ED processes with N-methylpyrrolidone(NMP)and dimethlac-etamide(DMCA)as entrainer,SA-PSD process with isopropyl-alcohol(IPA)as solvent and SA-PSD process with partial heat integration(PHI-PSD)are proposed to achieve high purity separation of a mixture of cyclohexane/2-butanol system.The optimal operating conditions of the processes are obtained after optimizing with NSGA-Ⅱ algorithm when total annual cost(TAC)and the entropy production of process are set as objectives.The optimal results show that the optimal PHI-PSD process has lower TAC by 28.7% and the lower entropy production by 39.5% than the optimal SA-PSD process while the ED process with NMP as entrainer has lower TAC by 50.9% and the lower entropy production by 56.1% than the optimal SA-PSD process.The optimal results show that the ED process with NMP as entrainer has the best economic and thermodynamic efficiency among the four proposed processes in this paper.
基金financially supported by the National Key R&D Program of China(no.2018YFB0604902)
文摘The benzene and acetonitrile azeotropic mixture was proposed to be separated by extractive distillation using an ionic liquid(IL)as the entrainer.The suitable IL was selected by the COSMO-RS model,and 1-ethyl-3-methylimidazolium tetrafluoroborate([EMIM][BF_(4)])was considered as the suitable entrainer mainly due to its high selectivity,low viscosity,and low price.The experimental vapor pressure data of the IL-containing systems(benzene+[EMIM][BF_(4)]and acetonitrile+[EMIM][BF_(4)])were measured in the full concentration range.The results show that acetonitrile has a stronger interaction with IL than benzene,and the low deviations between the experimental and UNIFAC predicted values show the reliability of the UNFIAC model.The UNIFAC predicted vapor-liquid equilibrium data of the benzene+acetonitrile+dimethyl sulfoxide(DMSO)/[EMIM][BF_(4)]system show that the relative volatility of benzene to acetonitrile is higher when the entrainer is[EMIM][BF_(4)].The process simulation results show that[EMIM][BF_(4)]can reduce the material and energy consumptions compared with DMSO.
基金support from the Program for the National Key R&D Program of China(2018YFB0604900)the National Natural Science Foundation of China(No.21878219)+1 种基金the financial support by the Natural Sciences and Engineering Research Council(NSERC)of Canada(RGPIN-4903-2014)China Scholarship Council(CSC)for supporting his doctoral study at McMaster University(No.201500090106)
文摘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.
基金financially supported by the National Key Research and Development Program of China(no.2018YFB0604702)
文摘The ionic liquid(IL)1-ethyl-3-methylimidazolium dicyanamide([EMIM][DCA])was selected as an appropriate entrainer for the extractive distillation of the methanol-ethanol-water mixture.The COSMO-RS model was applied to screen out the appropriate solvents considering selectivity and solvent capacity together.Isobaric vapor-liquid equilibrium(VLE)experiments for the two systems of methanol-water and ethanol-water with different amounts of[EMIM][DCA]added were conducted at 101.3 kPa.The experimental data showed that[EMIM][DCA]exhibits an obvious salting effect for the methanol(or ethanol)-water mixture and eliminates the azeotropic point of ethanol-water.Moreover,the predicted values by UNIFAC-Lei model coincide well with experimental data.The separation mechanism was further explained in combination with surface charge density distribution(σ-profiles),excess enthalpy(HE),and binding energy.In addition,the flow charts were designed to evaluate the improvement of energy consumption with[EMIM][DCA]as the entrainer when compared to ethylene glycol(EG).The simulation results demonstrated that[EMIM][DCA]is more energy efficient than EG.
基金supported by the Natural Science Foundation of Fujian Province,China(2021J01641)National Natural Science Foundation of China(21706062)the Scientific Research Starting Foundation of Fuzhou University,China(GXRC-18073)。
文摘Economically separating 1-propanol(NPA)from water is an emergent issue for producing pharmaceutical intermediates such as n-propyl acetate,n-propylamine and so on.In this work,fourionic liquids(ILs)1-ethyl-3-methylimidazolium thiocyanate([EMIM][SCN]),1-butyl-3-methylimidazolium tetrafluoroborate([BMIM][BF_(4)]),1,3-dimethylimidazolium methylsulfate([MMIM][MS]),1,3-dimethylimidazolium dimethylphosphate([MMIM][DMP])were introduced as potential entrainers for separating NPA–water azeotropic mixture.The results show that[MMIM][MS]is the most suitable entrainer compared with other ILs from the analysis of vapor-liquid equilibrium and relative volatilities.The extractive distillation process with the entrainer regeneration system of flash tank and stripper was employed and optimized by the two-step optimization method.The results show that total annual cost and energy consumption per product flow rate were reduced by 39.79%and 60.47%compared with literature.In addition,the efficiency indicator of extractive section,efficiency indicator of per tray in extractive section,carbon dioxide emissions were also selected as the evaluation index for selection of operating parameters and calculated for different cases.The CO_(2)emissions of the optimal design can be reduced by 60.98%from environmental aspect.
文摘In the present work,a comparative study of the extractive distillation and pressure swing distillation for methanol-acetonitrile separation is performed for the first time.Different separation alternatives,including the conventional extractive distillation,the extractive distillation with vapor or liquid side-stream,the pressure-swing distillation with or without full heat integration,and the heat-pump assisted pressure-swing distillation are rigorously simulated and optimized based on the minimum total annual cost(TAC)via the sequential iterative strategy.The results show that TAC and CO2 emission of the new extractive distillation with vapor side-stream(Vapor-SED)are similar to those of the extractive distillation with liquid side-stream(Liquid-SED).Furthermore,the Vapor-SED and Liquid-SED can achieve 30.01%and 30.56%reduction in TAC and 23.32%and 23.49%reduction in CO2 emission,respectively,over the most competitive fully heat-integrated PSD configuration.Hence,the extractive distillation with vapor or liquid side-stream appears to be a better option economically and environmentally for the separation of methanol and acetonitrile.
文摘To analyze the chemical constituents of volatile oils from the fruit of Periploca forrestii Schltr.which were collected in Guizhou province.This volatile oils were extracted by simultaneous distillation extraction (SDE)and microwave assistant extraction(MAE) method,and ananlyzed by gas chromatography-mass spectrometry(GC-MS)method.The main chemical compounds were methyl salicylate,β-amyrin and β-amyrin acetate etc.The compounds from the volatile oils extracted with SDE and MAE are quite different.The results provide scientific proof for the further development and utilization of Periploca forrestii Schltr.
基金provided by the National Key Research and Devolopment Program of China(2017YFB0702800)the National Natural Science Foundation of China (21878025, 22078026)。
文摘It is difficult to separate the methanol and hydrocarbons in the propylene oxide(PO)purification process due to their forming azeotrope.As for this,a novel PO separation process,in that the deionized water is employed as extractant and 1,2-propylene glycol(MPG)that is formed from the PO hydrolysis reaction is recovered,is presented in this work.The salient feature of this process is that both the non-catalyzed reactions of PO hydrolysis to form MPG and dipropylene glycol(DPG)are simultaneously considered and MPG by-product with high purity is obtained in virtue of the deionized water as reflux liquid and side take-off in MPG column.In addition,the ionic liquid(IL)extractant is screened through the conductorlike screening model for segment activity coefficient(COSMO-SAC)and the comparisons of separation efficiency between the IL and normal octane(nC_(8))extractant for the separation of PO and 2-methylpentane are made.With the non-random two-liquid(NRTL)thermodynamic model,the simulation and optimization design for the full flow sheet are performed and the effects of the key operation parameters such as solvent ratio,theoretical stages,feeding stage etc.on separation efficiency are detailedly discussed.The results show that the mass purity and the mass yield of PO can be up to 99.99%and 99.0%,and the condenser duty,reboiler duty and PO loss in the process with IL extractant can be decreased by 69.66%,30.21%and 78.86%compared to ones with nC_(8).The total annual cost(TAC)calculation also suggests that the TAC would be significantly reduced if using IL in replace of nC_(8) for the investigated process.The presented results would provide a useful guide for improving the quality of PO product and the economic efficiency of industrial plant.
基金supported by the National Natural Science Foundation of China(Grant No.21878028)the Chongqing Joint Chinese Medicine Scientific Research Project(Grant No.2020ZY023984)the Fundamental Research Funds for the Central Universities(Grant No.2022CDJXY-003).
文摘In the traditional extractive distillation process,organic solvents are often used as entrainers.However,environmental influence and high energy-consumption are significant problems in industrial application.In this study,a systematic screening strategy and innovative energy-saving design for ionic liquid-based extractive distillation process was proposed.The innovative energy-saving design focused on the binary minimum azeotrope mixtures isopropanol and water.Miscibility,environmental impact and physical properties(e.g.,melting point and viscosity)of 30 ionic liquids were investigated.1-Ethyl-3-methyl-imidazolium dicyanamide and 1-butyl-3-methyl-imidazolium dicyanamide were selected as candidate entrainers.Feasibility analysis of these two ionic liquids was further performed via residue curve maps,isovolatility line and temperature profiles.An innovative ionic liquid-based extractive distillation process combining distillation column and stripping column was designed and optimized with the objective function of minimizing the total annualized cost.The results demonstrate that the total annualized cost was reduced by 19.9%with 1-ethyl-3-methyl-imidazolium dicyanamide as the entrainer and by 24.3%with 1-butyl-3-methyl-imidazolium dicyanamide,compared with that of dimethyl sulfoxide.The method proposed in this study is conducive to the green and sustainable development of extractive distillation process.
基金This work is financially supported by the National Key Research and Development Project(Grant No.2019YFC0214403)the Joint Supervision Scheme with the mainland,Taiwan and Macao Universities(Grant No.SB2S to Yang A).
文摘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.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.21776145 and 21676152).
文摘The traditional approach to solvent selction in the extractive distillation process strictly focuses on the change in the relative voltility of light-heavy components induced by the solvent.However,the total annual cost of the process may not be minimal when the solvent induces the largest change in relative volatility.This work presents a heuristic method for selecting the optimal solvent to minimize the total annual cost.The functional relationship between the relative volatility and the total annual cost is established,where the main factors,such as the relative volatility of the light-heavy components and the relative volatility of the heavy-component solvent,are taken into account.Binary azeotropic mixtures of methanol-toluene and methanol-acetone are separated to verify the feasibility of the model.The results show that using the solvent with the minimal two-column extractive distillation index,the process achieves a minimal total annual cost.The method is conducive for sustainable advancements in chemistry and engineering because a suitable solvent can be selected without simulation verification.
