A technology of one-stage roughing and one-stage scavenging vanadium pre-concentration with shaking table was investigated for improving vanadium grade and decreasing acid consumption minerals content based on the qua...A technology of one-stage roughing and one-stage scavenging vanadium pre-concentration with shaking table was investigated for improving vanadium grade and decreasing acid consumption minerals content based on the quantitative evaluation of minerals by scanning electronic microscopy （QEMSCAN）. In order to visually illustrate how the vanadium-bearing minerals were separated from system, a loose-stratification model was established with Bagnold shear loose theory and Kelly stratification hypothesis. Through the model, it was inferred that fine fraction and coarse fraction of vanadium-bearing muscovite particles easily became the concentrate in roughing and scavenging stages, respectively. The type of the dominant effect on the loose-stratification was confirmed. In the roughing stage, gravity sedimentation played a leading role in the loose-stratification process. However, in the scavenging stage, shearing dispersion pressure caused by asymmetric motion of table deck took an important part in the loose-stratification process. Finally, the correction of the loose-stratification model was validated by the practical experiment.展开更多
Air separators provide safe, clean, and appropriate air flow to engines and are widely used in vehicles with large engines such as ships and submarines. In this operational study, the separation process in a Ranque-Hi...Air separators provide safe, clean, and appropriate air flow to engines and are widely used in vehicles with large engines such as ships and submarines. In this operational study, the separation process in a Ranque-Hilsch vortex tube cleaning （cooling） system is investigated to analyze the impact of the operating gas type on the vortex tube performance; the operating gases used are air, nitrogen, oxygen, carbon dioxide and nitrogen dioxide. The computational fluid dynamic model used is equipped with a three-dimensional structure, and the steady-state condition is applied during computations. The standard k-c turbulence model is employed to resolve nonlinear flow equations, and various key parameters, such as hot and cold exhaust thermal drops, and power separation rates, are described numerically. The results show that nitrogen dioxide creates the greatest separation power out of all gases tested, and the numerical results are validated by good agreement with available experimental data. In addition, a comparison is made between the use of two different boundary conditions, the pressure-far-field and the pressure-outlet, when analyzing complex turbulent flows in the air separators. Results present a comprehensive and practical solution for use in future numerical studies.展开更多
A mathematical model of the kinetics of thin-layer separation of granular materials by size stacked sieve classifiers based on the theory of Markov processes is constructed. The probability of screening in a cell in t...A mathematical model of the kinetics of thin-layer separation of granular materials by size stacked sieve classifiers based on the theory of Markov processes is constructed. The probability of screening in a cell in the shape and size of the holes and particle sieve material shared with the influence of the relative speed of their movement was determined. Residues on whole meal with sieves were identified by a kinetic model and numerical calculations, the efficacy of separation.展开更多
This paper reviewed various systems such as neutral phosphorus and acid phosphorus, carboxylic acid and amine extractant for solvent extraction chemistry of yttrium, including thermodynamics, kinetics and yttrium extr...This paper reviewed various systems such as neutral phosphorus and acid phosphorus, carboxylic acid and amine extractant for solvent extraction chemistry of yttrium, including thermodynamics, kinetics and yttrium extracting separation process containing the development course and new separation process.展开更多
The separation characteristics of the PVA-CS (polyvinyl alcohol-chitosan) blended composite membrane for dehydration of ethanol-water mixture are examined. The relationships of flux and separation factor with the feed...The separation characteristics of the PVA-CS (polyvinyl alcohol-chitosan) blended composite membrane for dehydration of ethanol-water mixture are examined. The relationships of flux and separation factor with the feed concentration and operation temperature are established. Using this correlated equation, the continuous-flow pervaporation process about 500 kilolitres/year dehydrated ethanol is designed. The numbers of stage and reheater are calculated by stage-by-stage method for two kinds of cascades: one with equal membrane area and the other with 10℃ of temperature decrement per section. The results show that when the numbers of stage and reheater are the same, the cascade with 10℃ of temperature decrement has more advantages than that with equal membrane area. The influences of feed concentration and flow rate on the numbers of stage and reheater in the cascades are discussed.展开更多
Dividing wall column(DWC)is shown to be energy efficient compared to conventional column sequence for multi components separation,which is used for olefin separation in fluidization methanol to propylene process in th...Dividing wall column(DWC)is shown to be energy efficient compared to conventional column sequence for multi components separation,which is used for olefin separation in fluidization methanol to propylene process in the present work.Detailed design for pilot DWC was performed and five control structures,i.e.composition control(CC),temperature control(TC),composition-temperature control(CC-TC),temperature difference control(TDC),double temperature difference control(DTDC)were proposed to circumvent feed disturbance.Sensitivity analysis and singular value decomposition(SVD)were used as criterion to select the controlled temperature locations in TC,CC-TC,TDC and DTDC control loops.The steady simulation result demonstrates that 25.7% and 30.2% duty can be saved for condenser and reboiler by substituting conventional column sequence with DWC,respectively.As for control structure selection,TC and TDC perform better than other three control schemes with smaller maximum deviation and shorter settling time.展开更多
In this work, a procedure to simulate the MD （molecular distillation） process for lactic acid purification was developed. The simulation was carried out with the aid of the Aspen Plus Process Simulator. Flash vessel...In this work, a procedure to simulate the MD （molecular distillation） process for lactic acid purification was developed. The simulation was carried out with the aid of the Aspen Plus Process Simulator. Flash vessel was used to represent the MD process since the software does not present this unit operation. The simulation results with efficiency factors were in agreement with previously reported experimental data.展开更多
This work describes the separation and purification of lactic acid from diluted solution by HSPE （hybrid short path evaporation） and RD （reactive distillation） as coupled process. The results showed that it is pos...This work describes the separation and purification of lactic acid from diluted solution by HSPE （hybrid short path evaporation） and RD （reactive distillation） as coupled process. The results showed that it is possible to increase lactic acid concentration up to 4.7 times higher than the raw material concentration.展开更多
A novel hydrothermal process was developed to extract zinc from pure zinc ferrite（ZnFe2O4） nanopowder and zinc-containing electric arc furnace（EAF） dust using hexahydrated ferric chloride（FeCl3-6H2O） as a decomp...A novel hydrothermal process was developed to extract zinc from pure zinc ferrite（ZnFe2O4） nanopowder and zinc-containing electric arc furnace（EAF） dust using hexahydrated ferric chloride（FeCl3-6H2O） as a decomposing agent.The effects of solid FeCl3-6H2O to ZnFe2O4 ratio by mass（RF/Z）,hydrothermal reaction temperature,and time on zinc extraction were systematically investigated.In the results,when the hydrothermal reaction is conducted at 150℃ for 2 h with RF/Z of 15：20,the efficiency of zinc extraction from ZnFe2O4 reaches97.2%,and the concentration of ferric ions（Fe^3＋） in the leaching solution is nearly zero,indicating a high selectivity for zinc.In addition,the zinc extraction efficiency from the EAF dust reaches 94.5%in the case of the hydrothermal reaction performed at 200℃ for 10 h with the solid FeCl3-6H2O to EAF dust ratio by mass（RF/EAF dust） of 15：10.Zinc and iron separation is achieved by adjusting the pH value of the leaching solution according to the different precipitation pH values of metal hydroxides.展开更多
A microporous zirconia membrane with hydrogen permeance about 5 × 10-8mol·m-2·s-1·Pa-1, H2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100 k Pa was f...A microporous zirconia membrane with hydrogen permeance about 5 × 10-8mol·m-2·s-1·Pa-1, H2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100 k Pa was fabricated via polymeric sol–gel process. The effect of calcination temperature on single gas permeance of sol–gel derived zirconia membranes was investigated. Zirconia membranes calcined at 350 °C and 400 °C showed similar single gas permeance, with permselectivities of hydrogen towards other gases, such as oxygen, nitrogen, methane, and sulfur hexa fluoride, around Knudsen values. A much lower CO2permeance（3.7 × 10-9mol·m-2·s-1·Pa-1）was observed due to the interaction between CO2 molecules and pore wall of membrane. Higher calcination temperature, 500 °C, led to the formation of mesoporous structure and, hence, the membrane lost its molecular sieving property towards hydrogen and carbon dioxide. The stability of zirconia membrane in the presence of hot steam was also investigated. Exposed to 100 k Pa steam for 400 h, the membrane performance kept unchanged in comparison with freshly prepared one, with hydrogen and carbon dioxide permeances of 4.7 × 10-8and ~ 3 × 10-9mol·m-2·s-1·Pa-1, respectively. Both H2 and CO2permeances of the zirconia membrane decreased with exposure time to 100 k Pa steam. With a total exposure time of 1250 h, the membrane presented hydrogen permeance of 2.4 × 10-8mol·m-2·s-1·Pa-1and H2/CO2 permselectivity of 28, indicating that the membrane retains its microporous structure.展开更多
Based on the petroleum processing units of a certain domestic refinery, the authors studied the appropriate cases for processing of Tahe medium gravity crude. The influence of three crude processing cases, including t...Based on the petroleum processing units of a certain domestic refinery, the authors studied the appropriate cases for processing of Tahe medium gravity crude. The influence of three crude processing cases, including the case for processing of crude slate blended with Tahe medium gravity crude, the case for separate processing and storing of individual crude oils, and the case for flash distillation of Tahe medium gravity crude coupled with separated processing of crude oils, on the products quality, stability of production operation and the overall techno-economic parameters was investigated. The study results have shown that the case for processing crude slate blended with Tahe medium gravity crude could lead to deterioration of the FCC products distribution, dramatic reduction of light distillates, significant surge of sulfur content in FCC naphtha, and increased specific consumption of FCC catalyst, indicating that this case was obviously not suited for processing the Tahe medium gravity crude. The case for separate processing and storing of individual crude oils, however, could increase the aggregate salable products ratio, but the frequent switchover of process streams could cause difficulty and hazards to the stabilization of refining operations, which could not be an ideal processing case. The case for flash distillation of Tahe medium gravity crude coupled with separate processing of crude oils featured the simplicity of process scheme, easiness for modification of process units, easy operation and a slight increase in the aggregate salable products ratio, making itself a suitable case for processing the Tahe medium gravity crude.展开更多
The binaphthol enantiomers separation process using simulation moving bed technology is simulated with the true moving bed approach （TMB）. In order to systematically optimize the process with multiple productive obj...The binaphthol enantiomers separation process using simulation moving bed technology is simulated with the true moving bed approach （TMB）. In order to systematically optimize the process with multiple productive objectives, this article develops a variant of tissue P system （TPS）. Inspired by general tissue P systems, the special TPS has a tissue-like structure with several membranes. The key rules of each membrane are the communication rule and mutation rule. These characteristics contribute to the diversity of the population, the conquest of the multimodal of objective function, and the convergence of algorithm. The results of comparison with a popular algorithm——the non-dominated sorting genetic algorithm 2（NSGA-2） illustrate that the new algorithm has satisfactory performance. Using the algorithm, this study maximizes synchronously several conflicting objectives, purities of different products, and productivity.展开更多
The high degree of reversibility of heat integrated distillation column(HIDiC) has been thermodynamically interpreted by the entropy method. In this paper, a heat transfer model and a more universal method were propos...The high degree of reversibility of heat integrated distillation column(HIDiC) has been thermodynamically interpreted by the entropy method. In this paper, a heat transfer model and a more universal method were proposed, through which the overall heat transfer coefficient at different height of column under different operating conditions could be obtained before the experiment. Then the separation of a binary ethanol-water system was carried out experimentally as a case study to verify the heat transfer model and the aforementioned calculation method. The close results between the calculation, the simulation, and the experiments suggested that the proposed model and the calculation method in this paper were accurate and applicable. Meanwhile, it was demonstrated that the HIDiC shows obvious effect of reducing entropy increase and improving thermodynamic efficiency as compared to conventional distillation column.展开更多
The separation process of oily water using membranes has attracted the attention of researchers and engineers. The greater problem in the use of membrane separation process is the reduction in permeate flux due to clo...The separation process of oily water using membranes has attracted the attention of researchers and engineers. The greater problem in the use of membrane separation process is the reduction in permeate flux due to clogged pores by oil deposition inside the membrane or by the effect of the concentration polarization. For this purpose, a theoretical study of a water/oil separation module was performed. This device consists of a tubular ceramic membrane provided with a rectangular inlet section. Numerical simulations were performed using Ansys CFX software to solve the mass and momentum conservation equations in the fluid and porous domains. Here was adopted the RNG k-ε turbulence model. The effect of the membrane porosity and the inlet velocity of the fluid mixture on the two-phase flow behavior inside the separation module were evaluated. Results of the volumetric fraction, velocity and pressure fields of the oil and water phases are presented and analyzed. The results indicate a higher oil concentration within the membrane for the cases of higher porosity, and that the inlet fluid mixture velocity does not substantially affect the velocity profile within the separation module. It is found that the maximum separation efficiency of the module was obtained with feed velocity of 40 m/s and membrane porosity of 0.44.展开更多
A facility of BaPS （Barometric Process Separation） was used to determine soil respiration, gross nitrification and denitrification in a winter wheat field with depths of 0-7, 7--14 and 14-21 cm. N2O production was d...A facility of BaPS （Barometric Process Separation） was used to determine soil respiration, gross nitrification and denitrification in a winter wheat field with depths of 0-7, 7--14 and 14-21 cm. N2O production was determined by a gas chromatograph. Crop root mass and relevant soil parameters were measured. Results showed that soil respiration and gross nitrification decreased with the increase of soil depth, while denitrification did not change significantly. In comparison with no-plowing plot, soil respiration increased significantly in plowing plot, especially in the surface soil of 0-7 cm, while gross nitrification and denitrification rates were not affected by plowing. Cropping practice in previous season was found to affect soil gross nitrification in the following wheat-growing season. Higher gross nitrification rate occurred in the filed plot with preceding crop of rice compared with that of maize for all the three depths of 0-7, 7-14 and 14-21 cm. A further investigation indicated that the nitrification for all the cases accounted for about 76% of the total nitrogen transformation processes of nitrification and denitrification and the N2O production correlated with nitrification significantly, suggesting that nitrification is a key process of soil N2O production in the wheat field. In addition, the variations of soil respiration and gross nitrification were exponentially dependent on root mass （p〈0.00l）.展开更多
Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustio...Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.展开更多
In a gas-solid separation fluidized bed,mixing of fine coal is necessary to achieve a suitable bed density to enable effective separation of low rank coal.On the basis of a variety of mixture models,a gas-solid separa...In a gas-solid separation fluidized bed,mixing of fine coal is necessary to achieve a suitable bed density to enable effective separation of low rank coal.On the basis of a variety of mixture models,a gas-solid separation fluidized bed was judged,where fine coal particles of 0.6-1.0mm were uniformly mixed with magnetite powder.High-speed dynamic camera technology was combined with a slump-sampling method to study the mixing process of the fine coal in the fluidized bed.These results showed that limitations of the fluidized bed structure cause the mixing process to be dominated by lateral diffusion and supplemented by axial diffusion.Axial diffusion was mainly achieved through the ascension of bubbles,whereas lateral diffusion was determined by the bursting action of the gas bubbles at the surface of the bed and the undulating characteristics of the bed.The effective lateral diffusion coefficient increased exponentially with gas velocity but had no strong relationship with the bed height.As the feed point moved toward the center,fine coal began to diffuse to both sides,which shortened the time for the bed density stabilization from 20 to 5 min.The bed density of the layer was stabilized at approximately 1.75 g/cm3.The separation efficiency of the gas-solid separation fluidized bed containing binary mixtures was more obvious for 6-50 mm raw coal,with a probable error E of 0.16.展开更多
This study described a hydrometallurgical method to investigate the separation of rare earth elements（REEs）from rare earth polishing powder wastes（REPPWs）containing large amounts of rare earth oxides with a major ...This study described a hydrometallurgical method to investigate the separation of rare earth elements（REEs）from rare earth polishing powder wastes（REPPWs）containing large amounts of rare earth oxides with a major phase of CeO2 and minor phases of La2O3,Pr2O3,and Nd2O3 using a process devised by the authors.The suggested approach consisted of five processes：the synthesis of NaR E（SO4）2·xH2O from rare earth oxides in Na2SO4-H2SO4-H2 O solutions（Process 1）,the conversion of NaR E（SO4）2·xH2O into RE（OH）3 using NaO H（Process 2）,and the oxidation of Ce（OH）3 into Ce（OH）4 using air with O2 injection（Process 3）,followed by Processes 4 and 5 for separation of REEs by acid leaching using HCl and H2SO4,respectively.To confirm the high yield of NaR E（SO4）2·xH2O in Process 1,experiments were carried out under various Na2SO4 concentrations（0.4–2.5 mol/L）,sulfuric acid concentrations（6–14 mol/L）,and reaction temperatures（95–125 oC）.In addition,the effect of the pH value on the separation of Ce（OH）4 in HCl-H2 O solutions with Ce（OH）4,La-,Pr-,and Nd（OH）3 in Process 4 was also investigated.On the basis of above results,the possibility of effective separation of REEs from REPPWs could be confirmed.展开更多
This study focused on the manufacture of microcrystalline cellulose(MCC)from wheat straw using environmentally-friendly solvents.Raw cellulose was separated from wheat straw after thermal decomposition of lignin follo...This study focused on the manufacture of microcrystalline cellulose(MCC)from wheat straw using environmentally-friendly solvents.Raw cellulose was separated from wheat straw after thermal decomposition of lignin followed by dissolution of lignin using a recyclable ethanol/acetic acid/water solvent system.Then,pure cellulose was produced using a four-step refining process,including chelating,O_(3),H_(2)O_(2),and xylanase treatments.Finally,MCC was obtained through hydrolysis,drying,and mechanical treatments.The effects of acetic acid,O_(3),H_(2)O_(2),NaOH,pretreatment time,and temperature on the properties of wheat straw cellulose(including Kappa number,yield,α-cellulose content,crystallinity,KMnO4 value,degree of polymerization(DP),and brightness)were investigated.The results showed that the addition of acetic acid enhanced lignin removal and hemicellulose degradation,improving the purity of the raw cellulose.The optimized acetic acid dosage in the wheat straw thermal decomposition step was 2%(w/w).The optimized O_(3)dosage was 1.2%(w/w).The optimized conditions for H_(2)O_(2)treatment were found to be 3%(w/w)H_(2)O_(2)and 1.8%(w/w)NaOH at 70°C for 120 min.The KMnO4 value was 2.0,brightness was 84.1%ISO,the viscosity was 934 mL/g,and the DP was 626 for refined cellulose.Xylanase effectively improved theα-cellulose content of wheat straw cellulose.With an optimized xylanase dosage of 1.5 IU/g,theα-cellulose content was 94.7%,the brightness was 85.6%ISO,and the DP was 615 for wheat straw cellulose.展开更多
基金Projects(2011BAB05B01,2011BA05B04)supported by the National Key Technology R&D Program during the 12th Five-year Plan Period,ChinaProject(201271031380)supported by Twilight Plane of Wuhan Youth Science and Technology,China
文摘A technology of one-stage roughing and one-stage scavenging vanadium pre-concentration with shaking table was investigated for improving vanadium grade and decreasing acid consumption minerals content based on the quantitative evaluation of minerals by scanning electronic microscopy （QEMSCAN）. In order to visually illustrate how the vanadium-bearing minerals were separated from system, a loose-stratification model was established with Bagnold shear loose theory and Kelly stratification hypothesis. Through the model, it was inferred that fine fraction and coarse fraction of vanadium-bearing muscovite particles easily became the concentrate in roughing and scavenging stages, respectively. The type of the dominant effect on the loose-stratification was confirmed. In the roughing stage, gravity sedimentation played a leading role in the loose-stratification process. However, in the scavenging stage, shearing dispersion pressure caused by asymmetric motion of table deck took an important part in the loose-stratification process. Finally, the correction of the loose-stratification model was validated by the practical experiment.
文摘Air separators provide safe, clean, and appropriate air flow to engines and are widely used in vehicles with large engines such as ships and submarines. In this operational study, the separation process in a Ranque-Hilsch vortex tube cleaning （cooling） system is investigated to analyze the impact of the operating gas type on the vortex tube performance; the operating gases used are air, nitrogen, oxygen, carbon dioxide and nitrogen dioxide. The computational fluid dynamic model used is equipped with a three-dimensional structure, and the steady-state condition is applied during computations. The standard k-c turbulence model is employed to resolve nonlinear flow equations, and various key parameters, such as hot and cold exhaust thermal drops, and power separation rates, are described numerically. The results show that nitrogen dioxide creates the greatest separation power out of all gases tested, and the numerical results are validated by good agreement with available experimental data. In addition, a comparison is made between the use of two different boundary conditions, the pressure-far-field and the pressure-outlet, when analyzing complex turbulent flows in the air separators. Results present a comprehensive and practical solution for use in future numerical studies.
文摘A mathematical model of the kinetics of thin-layer separation of granular materials by size stacked sieve classifiers based on the theory of Markov processes is constructed. The probability of screening in a cell in the shape and size of the holes and particle sieve material shared with the influence of the relative speed of their movement was determined. Residues on whole meal with sieves were identified by a kinetic model and numerical calculations, the efficacy of separation.
基金Project supported by the National Basic Research Program(973 Program)(2006CB403302)
文摘This paper reviewed various systems such as neutral phosphorus and acid phosphorus, carboxylic acid and amine extractant for solvent extraction chemistry of yttrium, including thermodynamics, kinetics and yttrium extracting separation process containing the development course and new separation process.
基金Supported by the National Natural Science Foundation of China(No.29836160) and Commission of Science & Technology of Zhejiang Province(No.924010,No.85-12-02-05).
文摘The separation characteristics of the PVA-CS (polyvinyl alcohol-chitosan) blended composite membrane for dehydration of ethanol-water mixture are examined. The relationships of flux and separation factor with the feed concentration and operation temperature are established. Using this correlated equation, the continuous-flow pervaporation process about 500 kilolitres/year dehydrated ethanol is designed. The numbers of stage and reheater are calculated by stage-by-stage method for two kinds of cascades: one with equal membrane area and the other with 10℃ of temperature decrement per section. The results show that when the numbers of stage and reheater are the same, the cascade with 10℃ of temperature decrement has more advantages than that with equal membrane area. The influences of feed concentration and flow rate on the numbers of stage and reheater in the cascades are discussed.
基金Supported by Open Research Project of State Key Laboratory of Chemical Engineering(Grant No.SKL-Ch E-16B06)
文摘Dividing wall column(DWC)is shown to be energy efficient compared to conventional column sequence for multi components separation,which is used for olefin separation in fluidization methanol to propylene process in the present work.Detailed design for pilot DWC was performed and five control structures,i.e.composition control(CC),temperature control(TC),composition-temperature control(CC-TC),temperature difference control(TDC),double temperature difference control(DTDC)were proposed to circumvent feed disturbance.Sensitivity analysis and singular value decomposition(SVD)were used as criterion to select the controlled temperature locations in TC,CC-TC,TDC and DTDC control loops.The steady simulation result demonstrates that 25.7% and 30.2% duty can be saved for condenser and reboiler by substituting conventional column sequence with DWC,respectively.As for control structure selection,TC and TDC perform better than other three control schemes with smaller maximum deviation and shorter settling time.
文摘In this work, a procedure to simulate the MD （molecular distillation） process for lactic acid purification was developed. The simulation was carried out with the aid of the Aspen Plus Process Simulator. Flash vessel was used to represent the MD process since the software does not present this unit operation. The simulation results with efficiency factors were in agreement with previously reported experimental data.
文摘This work describes the separation and purification of lactic acid from diluted solution by HSPE （hybrid short path evaporation） and RD （reactive distillation） as coupled process. The results showed that it is possible to increase lactic acid concentration up to 4.7 times higher than the raw material concentration.
基金supported by the National Basic Research Priorities Program of China (Nos. 2014CB643401 and 2013AA032003)the National Natural Science Foundation of China (No.51372019)
文摘A novel hydrothermal process was developed to extract zinc from pure zinc ferrite（ZnFe2O4） nanopowder and zinc-containing electric arc furnace（EAF） dust using hexahydrated ferric chloride（FeCl3-6H2O） as a decomposing agent.The effects of solid FeCl3-6H2O to ZnFe2O4 ratio by mass（RF/Z）,hydrothermal reaction temperature,and time on zinc extraction were systematically investigated.In the results,when the hydrothermal reaction is conducted at 150℃ for 2 h with RF/Z of 15：20,the efficiency of zinc extraction from ZnFe2O4 reaches97.2%,and the concentration of ferric ions（Fe^3＋） in the leaching solution is nearly zero,indicating a high selectivity for zinc.In addition,the zinc extraction efficiency from the EAF dust reaches 94.5%in the case of the hydrothermal reaction performed at 200℃ for 10 h with the solid FeCl3-6H2O to EAF dust ratio by mass（RF/EAF dust） of 15：10.Zinc and iron separation is achieved by adjusting the pH value of the leaching solution according to the different precipitation pH values of metal hydroxides.
基金Supported by the National Natural Science Foundation of China(21276123,21490581)the National High Technology Research and Development Program of China(2012AA03A606)+3 种基金State Key Laboratory of Materials-Oriented Chemical Engineering(ZK201002)the Natural Science Research Plan of Jiangsu Universities(11KJB530006)the "Summit of the Six Top Talents" Program of Jiangsu Provincea Project Funded by the Priority Academic Program development of Jiangsu Higher Education Institutions(PAPD)
文摘A microporous zirconia membrane with hydrogen permeance about 5 × 10-8mol·m-2·s-1·Pa-1, H2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100 k Pa was fabricated via polymeric sol–gel process. The effect of calcination temperature on single gas permeance of sol–gel derived zirconia membranes was investigated. Zirconia membranes calcined at 350 °C and 400 °C showed similar single gas permeance, with permselectivities of hydrogen towards other gases, such as oxygen, nitrogen, methane, and sulfur hexa fluoride, around Knudsen values. A much lower CO2permeance（3.7 × 10-9mol·m-2·s-1·Pa-1）was observed due to the interaction between CO2 molecules and pore wall of membrane. Higher calcination temperature, 500 °C, led to the formation of mesoporous structure and, hence, the membrane lost its molecular sieving property towards hydrogen and carbon dioxide. The stability of zirconia membrane in the presence of hot steam was also investigated. Exposed to 100 k Pa steam for 400 h, the membrane performance kept unchanged in comparison with freshly prepared one, with hydrogen and carbon dioxide permeances of 4.7 × 10-8and ~ 3 × 10-9mol·m-2·s-1·Pa-1, respectively. Both H2 and CO2permeances of the zirconia membrane decreased with exposure time to 100 k Pa steam. With a total exposure time of 1250 h, the membrane presented hydrogen permeance of 2.4 × 10-8mol·m-2·s-1·Pa-1and H2/CO2 permselectivity of 28, indicating that the membrane retains its microporous structure.
文摘Based on the petroleum processing units of a certain domestic refinery, the authors studied the appropriate cases for processing of Tahe medium gravity crude. The influence of three crude processing cases, including the case for processing of crude slate blended with Tahe medium gravity crude, the case for separate processing and storing of individual crude oils, and the case for flash distillation of Tahe medium gravity crude coupled with separated processing of crude oils, on the products quality, stability of production operation and the overall techno-economic parameters was investigated. The study results have shown that the case for processing crude slate blended with Tahe medium gravity crude could lead to deterioration of the FCC products distribution, dramatic reduction of light distillates, significant surge of sulfur content in FCC naphtha, and increased specific consumption of FCC catalyst, indicating that this case was obviously not suited for processing the Tahe medium gravity crude. The case for separate processing and storing of individual crude oils, however, could increase the aggregate salable products ratio, but the frequent switchover of process streams could cause difficulty and hazards to the stabilization of refining operations, which could not be an ideal processing case. The case for flash distillation of Tahe medium gravity crude coupled with separate processing of crude oils featured the simplicity of process scheme, easiness for modification of process units, easy operation and a slight increase in the aggregate salable products ratio, making itself a suitable case for processing the Tahe medium gravity crude.
基金Supported by the National Natural Science Foundation of China （No.60421002）
文摘The binaphthol enantiomers separation process using simulation moving bed technology is simulated with the true moving bed approach （TMB）. In order to systematically optimize the process with multiple productive objectives, this article develops a variant of tissue P system （TPS）. Inspired by general tissue P systems, the special TPS has a tissue-like structure with several membranes. The key rules of each membrane are the communication rule and mutation rule. These characteristics contribute to the diversity of the population, the conquest of the multimodal of objective function, and the convergence of algorithm. The results of comparison with a popular algorithm——the non-dominated sorting genetic algorithm 2（NSGA-2） illustrate that the new algorithm has satisfactory performance. Using the algorithm, this study maximizes synchronously several conflicting objectives, purities of different products, and productivity.
基金supported by the National Key Research and Development Program of China(2017YFB0602500)the Foundation for High Level Talents of Hebei (A2017002032).
文摘The high degree of reversibility of heat integrated distillation column(HIDiC) has been thermodynamically interpreted by the entropy method. In this paper, a heat transfer model and a more universal method were proposed, through which the overall heat transfer coefficient at different height of column under different operating conditions could be obtained before the experiment. Then the separation of a binary ethanol-water system was carried out experimentally as a case study to verify the heat transfer model and the aforementioned calculation method. The close results between the calculation, the simulation, and the experiments suggested that the proposed model and the calculation method in this paper were accurate and applicable. Meanwhile, it was demonstrated that the HIDiC shows obvious effect of reducing entropy increase and improving thermodynamic efficiency as compared to conventional distillation column.
文摘The separation process of oily water using membranes has attracted the attention of researchers and engineers. The greater problem in the use of membrane separation process is the reduction in permeate flux due to clogged pores by oil deposition inside the membrane or by the effect of the concentration polarization. For this purpose, a theoretical study of a water/oil separation module was performed. This device consists of a tubular ceramic membrane provided with a rectangular inlet section. Numerical simulations were performed using Ansys CFX software to solve the mass and momentum conservation equations in the fluid and porous domains. Here was adopted the RNG k-ε turbulence model. The effect of the membrane porosity and the inlet velocity of the fluid mixture on the two-phase flow behavior inside the separation module were evaluated. Results of the volumetric fraction, velocity and pressure fields of the oil and water phases are presented and analyzed. The results indicate a higher oil concentration within the membrane for the cases of higher porosity, and that the inlet fluid mixture velocity does not substantially affect the velocity profile within the separation module. It is found that the maximum separation efficiency of the module was obtained with feed velocity of 40 m/s and membrane porosity of 0.44.
基金The Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX1-SW-01-13)
文摘A facility of BaPS （Barometric Process Separation） was used to determine soil respiration, gross nitrification and denitrification in a winter wheat field with depths of 0-7, 7--14 and 14-21 cm. N2O production was determined by a gas chromatograph. Crop root mass and relevant soil parameters were measured. Results showed that soil respiration and gross nitrification decreased with the increase of soil depth, while denitrification did not change significantly. In comparison with no-plowing plot, soil respiration increased significantly in plowing plot, especially in the surface soil of 0-7 cm, while gross nitrification and denitrification rates were not affected by plowing. Cropping practice in previous season was found to affect soil gross nitrification in the following wheat-growing season. Higher gross nitrification rate occurred in the filed plot with preceding crop of rice compared with that of maize for all the three depths of 0-7, 7-14 and 14-21 cm. A further investigation indicated that the nitrification for all the cases accounted for about 76% of the total nitrogen transformation processes of nitrification and denitrification and the N2O production correlated with nitrification significantly, suggesting that nitrification is a key process of soil N2O production in the wheat field. In addition, the variations of soil respiration and gross nitrification were exponentially dependent on root mass （p〈0.00l）.
基金funded by the Helmholtz Association of German Research Centersthe funding given by the German Federal Ministry for Economic Affairs and Energy to finance the research project METPORE Ⅱ (03ET2016)+2 种基金the METPORE Ⅱ project partnersSSC Strategic Science Consult GmbHBORSIG Membrane Technology GmbH
文摘Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.
基金the National Natural Science Founda-tion of China(No.51774283,51221462)。
文摘In a gas-solid separation fluidized bed,mixing of fine coal is necessary to achieve a suitable bed density to enable effective separation of low rank coal.On the basis of a variety of mixture models,a gas-solid separation fluidized bed was judged,where fine coal particles of 0.6-1.0mm were uniformly mixed with magnetite powder.High-speed dynamic camera technology was combined with a slump-sampling method to study the mixing process of the fine coal in the fluidized bed.These results showed that limitations of the fluidized bed structure cause the mixing process to be dominated by lateral diffusion and supplemented by axial diffusion.Axial diffusion was mainly achieved through the ascension of bubbles,whereas lateral diffusion was determined by the bursting action of the gas bubbles at the surface of the bed and the undulating characteristics of the bed.The effective lateral diffusion coefficient increased exponentially with gas velocity but had no strong relationship with the bed height.As the feed point moved toward the center,fine coal began to diffuse to both sides,which shortened the time for the bed density stabilization from 20 to 5 min.The bed density of the layer was stabilized at approximately 1.75 g/cm3.The separation efficiency of the gas-solid separation fluidized bed containing binary mixtures was more obvious for 6-50 mm raw coal,with a probable error E of 0.16.
文摘This study described a hydrometallurgical method to investigate the separation of rare earth elements（REEs）from rare earth polishing powder wastes（REPPWs）containing large amounts of rare earth oxides with a major phase of CeO2 and minor phases of La2O3,Pr2O3,and Nd2O3 using a process devised by the authors.The suggested approach consisted of five processes：the synthesis of NaR E（SO4）2·xH2O from rare earth oxides in Na2SO4-H2SO4-H2 O solutions（Process 1）,the conversion of NaR E（SO4）2·xH2O into RE（OH）3 using NaO H（Process 2）,and the oxidation of Ce（OH）3 into Ce（OH）4 using air with O2 injection（Process 3）,followed by Processes 4 and 5 for separation of REEs by acid leaching using HCl and H2SO4,respectively.To confirm the high yield of NaR E（SO4）2·xH2O in Process 1,experiments were carried out under various Na2SO4 concentrations（0.4–2.5 mol/L）,sulfuric acid concentrations（6–14 mol/L）,and reaction temperatures（95–125 oC）.In addition,the effect of the pH value on the separation of Ce（OH）4 in HCl-H2 O solutions with Ce（OH）4,La-,Pr-,and Nd（OH）3 in Process 4 was also investigated.On the basis of above results,the possibility of effective separation of REEs from REPPWs could be confirmed.
基金the Doctoral Program of Higher Education Projects(for the priority development areas)by Ministry of Education of China(Grant No.20126125130001)State Key Laboratory of Pulp and Paper Engineering open foundation(Grant No.201505)the Doctoral Scientific Research Foundation(Grant No.BJ13-02)by Shaanxi University of Science and Technology.
文摘This study focused on the manufacture of microcrystalline cellulose(MCC)from wheat straw using environmentally-friendly solvents.Raw cellulose was separated from wheat straw after thermal decomposition of lignin followed by dissolution of lignin using a recyclable ethanol/acetic acid/water solvent system.Then,pure cellulose was produced using a four-step refining process,including chelating,O_(3),H_(2)O_(2),and xylanase treatments.Finally,MCC was obtained through hydrolysis,drying,and mechanical treatments.The effects of acetic acid,O_(3),H_(2)O_(2),NaOH,pretreatment time,and temperature on the properties of wheat straw cellulose(including Kappa number,yield,α-cellulose content,crystallinity,KMnO4 value,degree of polymerization(DP),and brightness)were investigated.The results showed that the addition of acetic acid enhanced lignin removal and hemicellulose degradation,improving the purity of the raw cellulose.The optimized acetic acid dosage in the wheat straw thermal decomposition step was 2%(w/w).The optimized O_(3)dosage was 1.2%(w/w).The optimized conditions for H_(2)O_(2)treatment were found to be 3%(w/w)H_(2)O_(2)and 1.8%(w/w)NaOH at 70°C for 120 min.The KMnO4 value was 2.0,brightness was 84.1%ISO,the viscosity was 934 mL/g,and the DP was 626 for refined cellulose.Xylanase effectively improved theα-cellulose content of wheat straw cellulose.With an optimized xylanase dosage of 1.5 IU/g,theα-cellulose content was 94.7%,the brightness was 85.6%ISO,and the DP was 615 for wheat straw cellulose.
