With the burgeoning growth of aquaculture industry,high concentration of NH_(4)^(+)-N,phosphorus and tetracycline are the prevalent pollutants in aquaculturewastewater posing a significant health risk to aquatic organ...With the burgeoning growth of aquaculture industry,high concentration of NH_(4)^(+)-N,phosphorus and tetracycline are the prevalent pollutants in aquaculturewastewater posing a significant health risk to aquatic organisms.Therefore,an effective method for treating aquaculture wastewater should be urgently explored.Simultaneous removal of NH_(4)^(+)-N,phosphorus,tetracycline,and chemical oxygen demand(COD)in aquaculture wastewater was developed bymoving bed biofilm reactor(MBBR)under co-metabolic substances.The result showed that co-metabolism substances had different effects on MBBR performance,and 79.4%of tetracycline,68.2%of NH_(4)^(+)-N,61.3%of total nitrogen,88.3%of COD,and 38.1%of total phosphorus(TP)were synchronously removed with sodium acetate as a co-metabolic carbon source.Protein(PN),polysaccharide(PS),and electron transfer system activity were used to evaluate the MBBR performances,suggesting that PN/PS ratio was 1.48,0.91,1.07,3.58,and 0.79 at phases Ⅰ-Ⅴ.Additionally,a mode of tetracycline degradation and TP removal was explored,and the cell apoptosis was evaluated by flow cytometry.The result suggested that 74%,83%,and 83%of tetracycline were degraded by extracellular extracts,intracellular extracts,and cell debris,and there was no difference between extracts and non-enzyme in TP removal.The ratio of viable and dead cells from biofilm reached 33.3%and 7.68%with sodium acetate as a co-metabolic carbon source.Furthermore,Proteobacteria and Bacteroidetes in biofilm were identified as the dominant phyla for tetracycline and nutrients removal.This study provides a new strategy for tetracycline and nutrients removal from aquaculture wastewater through co-metabolism.展开更多
Moving bed biofilm reactor （MBBR） was used to treat real coal gasification wastewater. Nitrification of the MBBR was inhibited almost completely during start-up period. Sudden increase of influent total NH 3 concent...Moving bed biofilm reactor （MBBR） was used to treat real coal gasification wastewater. Nitrification of the MBBR was inhibited almost completely during start-up period. Sudden increase of influent total NH 3 concentration was the main factor inducing nitrification inhibition. Increasing DO concentration in the bulk liquid （from 2 to 3 mg/L） had little effect on nitrification recovery. Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days. Nitrification ratio of the MBBR achieved 65% within 12 days by increasing dilute ratio of the influent wastewater with tap water. The ratio of nitrification decreased to 25% when influent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70% for another 4 days.展开更多
Nitrogen removal via nitrite （the nitrite pathway） is more suitable for carbon-limited industrial wastewater. Partial nitrification to nitrite is the primary step to achieve nitrogen removal via nitrite. The effect ...Nitrogen removal via nitrite （the nitrite pathway） is more suitable for carbon-limited industrial wastewater. Partial nitrification to nitrite is the primary step to achieve nitrogen removal via nitrite. The effect of alkalinity on nitrite accumulation in a continuous process was investigated by progressively increasing the alkalinity dosage ratio （amount of alkalinity to ammonia ratio, mol/mol）. There is a close relationship among alkalinity, pH and the state of matter present in aqueous solution. When alkalinity was insufficient （compared to the theoretical alkalinity amount）, ammonia removal efficiency increased first and then decreased at each alkalinity dosage ratio, with an abrupt removal efficiency peak. Generally, ammonia removal efficiency rose with increasing alkalinity dosage ratio. Ammonia removal efficiency reached to 88% from 23% when alkalinity addition was sufficient. Nitrite accumulation could be achieved by inhibiting nitrite oxidizing bacteria （NOB） by free ammonia （FA） in the early period and free nitrous acid in the later period of nitrification when alkalinity was not adequate. Only FA worked to inhibit the activity of NOB when alkalinity addition was sufficient.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
A non-linear non-ideal model, taking into account non-linear competitive isotherms, axial dispersion, film mass transfer, intraparticle diffusion, and port periodic switching, was developed to simulate the dynamics of...A non-linear non-ideal model, taking into account non-linear competitive isotherms, axial dispersion, film mass transfer, intraparticle diffusion, and port periodic switching, was developed to simulate the dynamics of simulated moving bed chromatography (SMBC). The model equations were solved by a new efficient numerical technique of orthogonal collocation on finite elements with periodical movement of concentration vector. The simulated SMBC performance is in accordance with the experimental results reported in the literature for separation of l,1'-bi-2-naphthol enantiomers using SMBC. This model is useful for design, operation, optimization and scale-up of non-linear SMBC for chiral separations with significant non-ideal effects, especially for high solute concentration and small intraparticle diffusion coefficient or large chiral stationary phase particle.展开更多
A rate model, which considers axial dispersion, external mass transfer, intraparticle diffusion and nonlinear isotherms, and ports periodic switching is adopted to simulate the simulated moving bed （SMB） process. Th...A rate model, which considers axial dispersion, external mass transfer, intraparticle diffusion and nonlinear isotherms, and ports periodic switching is adopted to simulate the simulated moving bed （SMB） process. The effects of flow rate in Sections 2 and 3 and switching time on the operating performance parameters： purity, recovery, productivity and dcsorbent consumption are studied. A simulation approach is applied to simulate the operation and performance of the SMB. The model predicts the performance of the transient and cyclic steady state behavior to a reasonably good extent, and provides guidance operation condition of the SMB process.展开更多
Asynchronous simulated moving bed chromatography (ASMBC), known also as the 'VARICOL' process, is more efficient and flexible than the well-known and traditional simulated moving bed chromatography (SMBC). A d...Asynchronous simulated moving bed chromatography (ASMBC), known also as the 'VARICOL' process, is more efficient and flexible than the well-known and traditional simulated moving bed chromatography (SMBC). A detailed model of ASMBC, taking account of non-linear competitive isotherms, mass transfer parameters, and complex port switching schedule parameters, was developed to simulate the complex dynamics of ASMBC.The simulated performance is in close agreement with the experimental data of chiral separation reported in the literature. The simulation results show that ASMBC can achieve the performance similar to SMBC with fewer columns and can achieve better performance than SMBC with the same total column number. All design and operation parameters can be chosen correctly by numerical simulation. This detailed ASMBC model and the numerical technique are useful for design, operation, optimization and scale-up of ASMBC.展开更多
A new feeding mode for a simulated moving bed(SMB) is proposed.The outlet stream from zone II is collected at regular intervals.The concentration of the solution is increased by dissolving raw materials and then fed t...A new feeding mode for a simulated moving bed(SMB) is proposed.The outlet stream from zone II is collected at regular intervals.The concentration of the solution is increased by dissolving raw materials and then fed to zone III as the feed stream during the next collection interval.In this feeding mode,the concentration of the stream fed to zone III is identical to that of original feed,while in a conventional SMB,the feed is diluted by mix-ing with the outlet stream of zone II before feeding to zone III.The new feeding mode increases the inlet concentra-tion of zone III.A modeling investigation shows that higher inlet concentration of zone III increases the height of concentration band in SMB,improving the separation performance significantly.In comparison with the traditonal feeding mode,the new feeding mode increases the productivity by 23.52%and decreases the solvent consumption by 22.56%,so as to increase the raffinate and extract concentrations by 53.17%and 20.38%,respectively.The col-lection interval for the outlet stream from zone II has no effect on the separation performance after reaching the steady state,so that the collection interval can be increased to make the operation more convenient.展开更多
Chromatograms of tocopherol homologues were obtained by a column of analytical size (inner diameter (ID) 0.46 cm cm×10 cm) packed with silica gel. Adsorption isotherms and film mass-transfer coefficient were esti...Chromatograms of tocopherol homologues were obtained by a column of analytical size (inner diameter (ID) 0.46 cm cm×10 cm) packed with silica gel. Adsorption isotherms and film mass-transfer coefficient were estimated from the chroma-tograms by using a general rate model, which considers axial dispersion, external mass-transfer and intraparticle diffusion. Based on the obtained isotherms and mass-transfer coefficient, the separation process of tocopherol homologues on simulated moving bed (SMB) was simulated using the same model. According to the simulated results, a mixture of α-, γ-, δ-tocopherols and other impurities was separated on an SMB equipment. The SMB equipment was composed of 8 columns of ID 2 cm×10 cm, with 2 columns in each section. The solid phase was silica gel, and the mobile phase was n-hexane/2-propanol (99/1 by volume). γ-and δ-tocopherols of purity greater than 98% were obtained with recovery greater than 98%. The effects of operating conditions (flow rates and switching time) on the performance of SMB were studied by both simulation and experiments. It was found that all the simulation results were quite close to the experimental results. We conclude that process development and optimization of operating conditions of SMB by simulation are feasible.展开更多
A two-feed simulated moving bed（SMB） was proposed to utilize the stationary phase more effectively.Zone I is disconnected with zone Ⅱ and zone Ⅲ is disconnected with zone IV.Two feeds are added to zones I and Ⅲ,w...A two-feed simulated moving bed（SMB） was proposed to utilize the stationary phase more effectively.Zone I is disconnected with zone Ⅱ and zone Ⅲ is disconnected with zone IV.Two feeds are added to zones I and Ⅲ,while two desorbents are added to zones Ⅱ and IV separately.The investigation on the movement of concentra-tion bands indicated that the tail of the strong retained solute and the front of the weak retained solute were eluted from zones I and Ⅲ orderly,so the streams from zones I and Ⅲ could be cut into different fractions to give the products with high purity.The two-feed SMB was used to separate α-tocopherol from its homologue mixture suc-cessfully,and could double the productivity if both feeds were identical to the feed in the conventional four-zone SMB.The solvent consumption could be reduced by reusing the middle fraction without solutes.展开更多
In this paper, a novel data mining method is introduced to solve the multi-objective optimization problems of process industry. A hyperrectangle association rule mining （HARM） algorithm based on support vector machi...In this paper, a novel data mining method is introduced to solve the multi-objective optimization problems of process industry. A hyperrectangle association rule mining （HARM） algorithm based on support vector machines （SVMs） is proposed. Hyperrectangles rules are constructed on the base of prototypes and support vectors （SVs） under some heuristic limitations. The proposed algorithm is applied to a simulated moving bed （SMB） paraxylene （PX） adsorption process. The relationships between the key process variables and some objective variables such as purity, recovery rate of PX are obtained. Using existing domain knowledge about PX adsorption process, most of the obtained association rules can be explained.展开更多
The salt-gradient operation mode used in ion-exchange simulated moving bed chromatography (SMBC) can improve the efficiency of protein separations. A detailed model that takes into account any kind of adsorption/ion-e...The salt-gradient operation mode used in ion-exchange simulated moving bed chromatography (SMBC) can improve the efficiency of protein separations. A detailed model that takes into account any kind of adsorption/ion-exchange equilibrium, salt gradient, size exclusion, mass transfer resistance, and port periodic switching mechanism, was developed to simulate the complex dynamics. The model predictions were verified by the experimental data on upward and downward gradients for protein separations reported in the literature. All design and operating parameters (number, configuration, length and diameter of columns, particle size, switching period, flow rates of feed, raffinate, desorbent and extract, protein concentrations in feed, different salt concentrations in desorbent and feed) can be chosen correctly by numerical simulation. This model can facilitate the design, operation, optimization, control and scale-up of salt-gradient ion-exchange SMBC for protein separations.展开更多
A simulated moving bed (SMB), equipped with eight silica-gel columns, was used to separate phosphatidylcholine (PC) from soybean phospholipids. The effects of flow rate in Sections 2 (Q2) and 3 (Q3), switching time, f...A simulated moving bed (SMB), equipped with eight silica-gel columns, was used to separate phosphatidylcholine (PC) from soybean phospholipids. The effects of flow rate in Sections 2 (Q2) and 3 (Q3), switching time, feed flow rate and feed concentration on the operating performance parameters: purity, recovery, productivity and desorbent consumption were studied. Operating conditions leading to more than 90% purity in both outlet streams have been identified, together with those achieving optimal performance. Regions leading to complete separation are observed and explained theoretically. As the mass-transfer effect was not considered, the triangle theory only gives initial guesses for the optimal operating conditions.展开更多
In this work, sesamin and sesamolin is separated and purified by SMB （simulated moving bed） chromatography. Purity of sesamin and sesamolin can reach 99.2% and 99.9 %, and they can be recovered by 99.9% and 99.4%, r...In this work, sesamin and sesamolin is separated and purified by SMB （simulated moving bed） chromatography. Purity of sesamin and sesamolin can reach 99.2% and 99.9 %, and they can be recovered by 99.9% and 99.4%, respectively. Concentrations of the extract and raffinate was monitored and periodical change of the concentration was observed on experiment. Effects of non-linear adsorption, dead volume, and temperature on the separation are reviewed by the triangle theory to explain the periodical change of concentration. It is found that dead volume has little effect, and temperature fluctuation significantly affects thc separation by SMB. The temperature seriously affects the robust operation of SMB due to the change of Henry＇s constant, which will change the selectivity and restrain the productivity. Although the productivity in this study is only 0.0416 g/L-hr, the cost of the stationary phase used in this study is much lower than that of packed in analytical column. By using this stationary phase, the authors are still able to separate the mixture of sesamin and sesmolin. This will economically attract attention for the application of SMB to purify bioactive compounds on developing botanical drugs.展开更多
For the alkylation of benzene with long-chain olefins, using Hβzeolite catalyst as replacement of HF or AlCl3 has the advantages of no corrosion, less environmental pollution, and much more 2-phenyl isomer, which has...For the alkylation of benzene with long-chain olefins, using Hβzeolite catalyst as replacement of HF or AlCl3 has the advantages of no corrosion, less environmental pollution, and much more 2-phenyl isomer, which has the highest biodegradability and solubility, and better detergent properties among the related isomers. The characterization of the coke shows that the deactivation of catalyst is caused by the jam of bulkier molecules, such as naphthalene, indane and linear alkylbenzenes, which are too big to move quickly in the intracrystalline pores of catalyst. The deactivated catalyst can be regenerated by benzene washing at higher temperature. To make the processes of reaction and regeneration continuous, a novel moving bed reactor is developed. Comparing with the processes with fixed bed reactors, the processes in this work have the advantages of continuous operation, low temperature, low pressure, low mole ratio of benzene to olefins, and high weight hourly space velocity.展开更多
We present an entropy production formulationn for a gas-solid moving bed reactor,which we have not seen in any published reference. Apart from the traditional “flows” and “forces”,e. g., those for heat conduction ...We present an entropy production formulationn for a gas-solid moving bed reactor,which we have not seen in any published reference. Apart from the traditional “flows” and “forces”,e. g., those for heat conduction and mass diffusions in each phase , we introduced the heterogeneouseffects: gas-solid heat and mass transfer, which lead to some new flows and forces in the entropyproduction formulation.展开更多
The application of a new type of moving bed reactor with draft tube for coal gasification was investigated. Successful coal gasification experiments were achieved using the coal gasifier. Product gas containing hydrog...The application of a new type of moving bed reactor with draft tube for coal gasification was investigated. Successful coal gasification experiments were achieved using the coal gasifier. Product gas containing hydrogen as high as 60% was obtained, and the calorific value of the product of 10 MJ·m-3 was obtained using air as oxidant. The reaction temperature of coal gasification in the moving bed was maintained at 870 °C which was comparatively low for coal gasification. Maximum coal gasification efficiency of 92% was obtained.展开更多
High-quality carbon nanotubes were continuously produced by using moving bed reactor. The studies of scanning electron microscopy and transmission electron microscopy reveal their homogeneity both in inner (similar to...High-quality carbon nanotubes were continuously produced by using moving bed reactor. The studies of scanning electron microscopy and transmission electron microscopy reveal their homogeneity both in inner (similar to 10 nm) and outer diameter (20-40 nm) of the tubes. The studies of X-ray photoelectron spectroscopy and the oxidation of carbon nanotubes in air demonstrate that the tubes have good graphitic degree.展开更多
<span style="font-family:Verdana;">A unique laboratory scale auto-thermal moving bed gasifier was designed for studyin</span><span style="font-family:Verdana;">g the thermochemica...<span style="font-family:Verdana;">A unique laboratory scale auto-thermal moving bed gasifier was designed for studyin</span><span style="font-family:Verdana;">g the thermochemical conversion of coal-biomass blends. </span><span style="font-family:Verdana;">For th</span><span style="font-family:Verdana;">is purpose, two coals (lignite and sub-bituminous), two biomass materials (corn stover and switchgrass)</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> and their respective blends were used. Gasification characteristics of the fuels were evaluated with an emphasis on improving the producer gas composition. The efficiency and product gas compositions reveal that utilizing </span><span style="font-family:Verdana;">the</span><span style="font-family:Verdana;"> inner stainless-steel tubing better promotes heat transfer upwards in the axial direction when compared to utilizing quartz insulation. The H<sub>2</sub>/CO ratio at </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">same operating conditions is much higher due to the increase in bed temperature and heat transfer upwards in the axial direction. This improved the overall efficiency by at least 20%. Using pure oxygen and steam, efficiency greater than 50% was obtained for blends with corn stover at steam to oxygen ratio of 2:1. Also, using air as the gasifying agent greatly improved the H<sub>2</sub>/CO ratios and overall efficiency in blends with corn stover. In contrast, blends with switchgrass were not very effective with respect to the overall gasification characteristics. Blending switchgrass with coal may not be viable option from the viewpoint of generating high quality producer gas for downstream operations.</span>展开更多
This work deals with the determination of the temperature profile within a direct heating<span style="font-family:;" "=""> </span><span style="font-family:;" "=&q...This work deals with the determination of the temperature profile within a direct heating<span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">moving bed </span><span style="font-family:Verdana;">torrefier</span> <span style="font-family:Verdana;">in order to</span><span style="font-family:Verdana;"> determine its minimum column height. A thermal model based on </span><span style="font-family:Verdana;">eulerian-eulerian</span> <span style="font-family:Verdana;">two</span></span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">phase</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> solid-gas theory was performed and solved with the method of lines. </span><span style="font-family:Verdana;">In addition</span><span style="font-family:Verdana;">, this study allows </span><span style="font-family:Verdana;">to investigate</span><span style="font-family:Verdana;"> the effect of the biomass particle size on the minimum </span><span style="font-family:Verdana;">torrefier</span><span style="font-family:Verdana;"> column height. This</span></span><span style="font-family:Verdana;"> investigation </span><span style="font-family:Verdana;">was performed by changing, simultaneously, the diameter of particles and the minimum fluidization velocity of the bed. Then, the calculations were made for a counter-current torrefaction reactor of 30</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">cm in diameter and </span><span style="font-family:Verdana;">for</span><span style="font-family:Verdana;"> 5</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">kg/h of the feed rate of raw sugarcane bagasse.</span><span style="font-family:Verdana;"> Results show that the height of the reactor column must be at least 30 cm for that are 1 mm in diameter and 108 cm for particles that are 2 mm in diameter.</span>展开更多
基金supported by the Research Support Project for Stabilizing and Introducing Talents of Anhui Agricultural University(No.rc522010).
文摘With the burgeoning growth of aquaculture industry,high concentration of NH_(4)^(+)-N,phosphorus and tetracycline are the prevalent pollutants in aquaculturewastewater posing a significant health risk to aquatic organisms.Therefore,an effective method for treating aquaculture wastewater should be urgently explored.Simultaneous removal of NH_(4)^(+)-N,phosphorus,tetracycline,and chemical oxygen demand(COD)in aquaculture wastewater was developed bymoving bed biofilm reactor(MBBR)under co-metabolic substances.The result showed that co-metabolism substances had different effects on MBBR performance,and 79.4%of tetracycline,68.2%of NH_(4)^(+)-N,61.3%of total nitrogen,88.3%of COD,and 38.1%of total phosphorus(TP)were synchronously removed with sodium acetate as a co-metabolic carbon source.Protein(PN),polysaccharide(PS),and electron transfer system activity were used to evaluate the MBBR performances,suggesting that PN/PS ratio was 1.48,0.91,1.07,3.58,and 0.79 at phases Ⅰ-Ⅴ.Additionally,a mode of tetracycline degradation and TP removal was explored,and the cell apoptosis was evaluated by flow cytometry.The result suggested that 74%,83%,and 83%of tetracycline were degraded by extracellular extracts,intracellular extracts,and cell debris,and there was no difference between extracts and non-enzyme in TP removal.The ratio of viable and dead cells from biofilm reached 33.3%and 7.68%with sodium acetate as a co-metabolic carbon source.Furthermore,Proteobacteria and Bacteroidetes in biofilm were identified as the dominant phyla for tetracycline and nutrients removal.This study provides a new strategy for tetracycline and nutrients removal from aquaculture wastewater through co-metabolism.
基金supported by the High Technology Research and Development Program(863)of China(No.2007AA06A411)
文摘Moving bed biofilm reactor （MBBR） was used to treat real coal gasification wastewater. Nitrification of the MBBR was inhibited almost completely during start-up period. Sudden increase of influent total NH 3 concentration was the main factor inducing nitrification inhibition. Increasing DO concentration in the bulk liquid （from 2 to 3 mg/L） had little effect on nitrification recovery. Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days. Nitrification ratio of the MBBR achieved 65% within 12 days by increasing dilute ratio of the influent wastewater with tap water. The ratio of nitrification decreased to 25% when influent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70% for another 4 days.
基金supported by the State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.2013DX10)the National Water Special Funds of China(No.2008ZX07207)
文摘Nitrogen removal via nitrite （the nitrite pathway） is more suitable for carbon-limited industrial wastewater. Partial nitrification to nitrite is the primary step to achieve nitrogen removal via nitrite. The effect of alkalinity on nitrite accumulation in a continuous process was investigated by progressively increasing the alkalinity dosage ratio （amount of alkalinity to ammonia ratio, mol/mol）. There is a close relationship among alkalinity, pH and the state of matter present in aqueous solution. When alkalinity was insufficient （compared to the theoretical alkalinity amount）, ammonia removal efficiency increased first and then decreased at each alkalinity dosage ratio, with an abrupt removal efficiency peak. Generally, ammonia removal efficiency rose with increasing alkalinity dosage ratio. Ammonia removal efficiency reached to 88% from 23% when alkalinity addition was sufficient. Nitrite accumulation could be achieved by inhibiting nitrite oxidizing bacteria （NOB） by free ammonia （FA） in the early period and free nitrous acid in the later period of nitrification when alkalinity was not adequate. Only FA worked to inhibit the activity of NOB when alkalinity addition was sufficient.
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 Natural Science Foundation of China(No.20206027)and the Natural Science Foundation of Zhejiang Province(No.202046).
文摘A non-linear non-ideal model, taking into account non-linear competitive isotherms, axial dispersion, film mass transfer, intraparticle diffusion, and port periodic switching, was developed to simulate the dynamics of simulated moving bed chromatography (SMBC). The model equations were solved by a new efficient numerical technique of orthogonal collocation on finite elements with periodical movement of concentration vector. The simulated SMBC performance is in accordance with the experimental results reported in the literature for separation of l,1'-bi-2-naphthol enantiomers using SMBC. This model is useful for design, operation, optimization and scale-up of non-linear SMBC for chiral separations with significant non-ideal effects, especially for high solute concentration and small intraparticle diffusion coefficient or large chiral stationary phase particle.
基金Supported by the Doctoral Program Foundation of the Institution of Higher Education of China (No.20040335045).
文摘A rate model, which considers axial dispersion, external mass transfer, intraparticle diffusion and nonlinear isotherms, and ports periodic switching is adopted to simulate the simulated moving bed （SMB） process. The effects of flow rate in Sections 2 and 3 and switching time on the operating performance parameters： purity, recovery, productivity and dcsorbent consumption are studied. A simulation approach is applied to simulate the operation and performance of the SMB. The model predicts the performance of the transient and cyclic steady state behavior to a reasonably good extent, and provides guidance operation condition of the SMB process.
基金Supported by the National Natural Science Foundation of China (No. 20206027), the Natural Science Foundation of Zhejiang Province (No. 202046)the National 973 Program of China (No. 2002CB312200).
文摘Asynchronous simulated moving bed chromatography (ASMBC), known also as the 'VARICOL' process, is more efficient and flexible than the well-known and traditional simulated moving bed chromatography (SMBC). A detailed model of ASMBC, taking account of non-linear competitive isotherms, mass transfer parameters, and complex port switching schedule parameters, was developed to simulate the complex dynamics of ASMBC.The simulated performance is in close agreement with the experimental data of chiral separation reported in the literature. The simulation results show that ASMBC can achieve the performance similar to SMBC with fewer columns and can achieve better performance than SMBC with the same total column number. All design and operation parameters can be chosen correctly by numerical simulation. This detailed ASMBC model and the numerical technique are useful for design, operation, optimization and scale-up of ASMBC.
基金Supported by the Natural Science Foundation of Ningbo（2009A610153）
文摘A new feeding mode for a simulated moving bed(SMB) is proposed.The outlet stream from zone II is collected at regular intervals.The concentration of the solution is increased by dissolving raw materials and then fed to zone III as the feed stream during the next collection interval.In this feeding mode,the concentration of the stream fed to zone III is identical to that of original feed,while in a conventional SMB,the feed is diluted by mix-ing with the outlet stream of zone II before feeding to zone III.The new feeding mode increases the inlet concentra-tion of zone III.A modeling investigation shows that higher inlet concentration of zone III increases the height of concentration band in SMB,improving the separation performance significantly.In comparison with the traditonal feeding mode,the new feeding mode increases the productivity by 23.52%and decreases the solvent consumption by 22.56%,so as to increase the raffinate and extract concentrations by 53.17%and 20.38%,respectively.The col-lection interval for the outlet stream from zone II has no effect on the separation performance after reaching the steady state,so that the collection interval can be increased to make the operation more convenient.
基金Project (No. 20040335045) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘Chromatograms of tocopherol homologues were obtained by a column of analytical size (inner diameter (ID) 0.46 cm cm×10 cm) packed with silica gel. Adsorption isotherms and film mass-transfer coefficient were estimated from the chroma-tograms by using a general rate model, which considers axial dispersion, external mass-transfer and intraparticle diffusion. Based on the obtained isotherms and mass-transfer coefficient, the separation process of tocopherol homologues on simulated moving bed (SMB) was simulated using the same model. According to the simulated results, a mixture of α-, γ-, δ-tocopherols and other impurities was separated on an SMB equipment. The SMB equipment was composed of 8 columns of ID 2 cm×10 cm, with 2 columns in each section. The solid phase was silica gel, and the mobile phase was n-hexane/2-propanol (99/1 by volume). γ-and δ-tocopherols of purity greater than 98% were obtained with recovery greater than 98%. The effects of operating conditions (flow rates and switching time) on the performance of SMB were studied by both simulation and experiments. It was found that all the simulation results were quite close to the experimental results. We conclude that process development and optimization of operating conditions of SMB by simulation are feasible.
基金Supported by the Natural Science Foundation of Ningbo,China (2009A610153)Analysis & Measurement Foundation ofZhejiang (2009F70066)Education Bureau of Ningbo,China (Jd090222)
文摘A two-feed simulated moving bed（SMB） was proposed to utilize the stationary phase more effectively.Zone I is disconnected with zone Ⅱ and zone Ⅲ is disconnected with zone IV.Two feeds are added to zones I and Ⅲ,while two desorbents are added to zones Ⅱ and IV separately.The investigation on the movement of concentra-tion bands indicated that the tail of the strong retained solute and the front of the weak retained solute were eluted from zones I and Ⅲ orderly,so the streams from zones I and Ⅲ could be cut into different fractions to give the products with high purity.The two-feed SMB was used to separate α-tocopherol from its homologue mixture suc-cessfully,and could double the productivity if both feeds were identical to the feed in the conventional four-zone SMB.The solvent consumption could be reduced by reusing the middle fraction without solutes.
基金Supported by the National Natural Science Foundation of China (No. 60421002)National Outstanding Youth Science Foundation of China (No. 60025308)the New Century 151 Talent Project of Zhejiang Province.
文摘In this paper, a novel data mining method is introduced to solve the multi-objective optimization problems of process industry. A hyperrectangle association rule mining （HARM） algorithm based on support vector machines （SVMs） is proposed. Hyperrectangles rules are constructed on the base of prototypes and support vectors （SVs） under some heuristic limitations. The proposed algorithm is applied to a simulated moving bed （SMB） paraxylene （PX） adsorption process. The relationships between the key process variables and some objective variables such as purity, recovery rate of PX are obtained. Using existing domain knowledge about PX adsorption process, most of the obtained association rules can be explained.
文摘The salt-gradient operation mode used in ion-exchange simulated moving bed chromatography (SMBC) can improve the efficiency of protein separations. A detailed model that takes into account any kind of adsorption/ion-exchange equilibrium, salt gradient, size exclusion, mass transfer resistance, and port periodic switching mechanism, was developed to simulate the complex dynamics. The model predictions were verified by the experimental data on upward and downward gradients for protein separations reported in the literature. All design and operating parameters (number, configuration, length and diameter of columns, particle size, switching period, flow rates of feed, raffinate, desorbent and extract, protein concentrations in feed, different salt concentrations in desorbent and feed) can be chosen correctly by numerical simulation. This model can facilitate the design, operation, optimization, control and scale-up of salt-gradient ion-exchange SMBC for protein separations.
基金Project (No. 20040335045) supported by the Specialized ResearchFund for the Doctoral Program of Higher Education of China
文摘A simulated moving bed (SMB), equipped with eight silica-gel columns, was used to separate phosphatidylcholine (PC) from soybean phospholipids. The effects of flow rate in Sections 2 (Q2) and 3 (Q3), switching time, feed flow rate and feed concentration on the operating performance parameters: purity, recovery, productivity and desorbent consumption were studied. Operating conditions leading to more than 90% purity in both outlet streams have been identified, together with those achieving optimal performance. Regions leading to complete separation are observed and explained theoretically. As the mass-transfer effect was not considered, the triangle theory only gives initial guesses for the optimal operating conditions.
文摘In this work, sesamin and sesamolin is separated and purified by SMB （simulated moving bed） chromatography. Purity of sesamin and sesamolin can reach 99.2% and 99.9 %, and they can be recovered by 99.9% and 99.4%, respectively. Concentrations of the extract and raffinate was monitored and periodical change of the concentration was observed on experiment. Effects of non-linear adsorption, dead volume, and temperature on the separation are reviewed by the triangle theory to explain the periodical change of concentration. It is found that dead volume has little effect, and temperature fluctuation significantly affects thc separation by SMB. The temperature seriously affects the robust operation of SMB due to the change of Henry＇s constant, which will change the selectivity and restrain the productivity. Although the productivity in this study is only 0.0416 g/L-hr, the cost of the stationary phase used in this study is much lower than that of packed in analytical column. By using this stationary phase, the authors are still able to separate the mixture of sesamin and sesmolin. This will economically attract attention for the application of SMB to purify bioactive compounds on developing botanical drugs.
文摘For the alkylation of benzene with long-chain olefins, using Hβzeolite catalyst as replacement of HF or AlCl3 has the advantages of no corrosion, less environmental pollution, and much more 2-phenyl isomer, which has the highest biodegradability and solubility, and better detergent properties among the related isomers. The characterization of the coke shows that the deactivation of catalyst is caused by the jam of bulkier molecules, such as naphthalene, indane and linear alkylbenzenes, which are too big to move quickly in the intracrystalline pores of catalyst. The deactivated catalyst can be regenerated by benzene washing at higher temperature. To make the processes of reaction and regeneration continuous, a novel moving bed reactor is developed. Comparing with the processes with fixed bed reactors, the processes in this work have the advantages of continuous operation, low temperature, low pressure, low mole ratio of benzene to olefins, and high weight hourly space velocity.
文摘We present an entropy production formulationn for a gas-solid moving bed reactor,which we have not seen in any published reference. Apart from the traditional “flows” and “forces”,e. g., those for heat conduction and mass diffusions in each phase , we introduced the heterogeneouseffects: gas-solid heat and mass transfer, which lead to some new flows and forces in the entropyproduction formulation.
文摘The application of a new type of moving bed reactor with draft tube for coal gasification was investigated. Successful coal gasification experiments were achieved using the coal gasifier. Product gas containing hydrogen as high as 60% was obtained, and the calorific value of the product of 10 MJ·m-3 was obtained using air as oxidant. The reaction temperature of coal gasification in the moving bed was maintained at 870 °C which was comparatively low for coal gasification. Maximum coal gasification efficiency of 92% was obtained.
基金the Presidential Foundation of Chinese Academy of Sciences.
文摘High-quality carbon nanotubes were continuously produced by using moving bed reactor. The studies of scanning electron microscopy and transmission electron microscopy reveal their homogeneity both in inner (similar to 10 nm) and outer diameter (20-40 nm) of the tubes. The studies of X-ray photoelectron spectroscopy and the oxidation of carbon nanotubes in air demonstrate that the tubes have good graphitic degree.
文摘<span style="font-family:Verdana;">A unique laboratory scale auto-thermal moving bed gasifier was designed for studyin</span><span style="font-family:Verdana;">g the thermochemical conversion of coal-biomass blends. </span><span style="font-family:Verdana;">For th</span><span style="font-family:Verdana;">is purpose, two coals (lignite and sub-bituminous), two biomass materials (corn stover and switchgrass)</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> and their respective blends were used. Gasification characteristics of the fuels were evaluated with an emphasis on improving the producer gas composition. The efficiency and product gas compositions reveal that utilizing </span><span style="font-family:Verdana;">the</span><span style="font-family:Verdana;"> inner stainless-steel tubing better promotes heat transfer upwards in the axial direction when compared to utilizing quartz insulation. The H<sub>2</sub>/CO ratio at </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">same operating conditions is much higher due to the increase in bed temperature and heat transfer upwards in the axial direction. This improved the overall efficiency by at least 20%. Using pure oxygen and steam, efficiency greater than 50% was obtained for blends with corn stover at steam to oxygen ratio of 2:1. Also, using air as the gasifying agent greatly improved the H<sub>2</sub>/CO ratios and overall efficiency in blends with corn stover. In contrast, blends with switchgrass were not very effective with respect to the overall gasification characteristics. Blending switchgrass with coal may not be viable option from the viewpoint of generating high quality producer gas for downstream operations.</span>
文摘This work deals with the determination of the temperature profile within a direct heating<span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">moving bed </span><span style="font-family:Verdana;">torrefier</span> <span style="font-family:Verdana;">in order to</span><span style="font-family:Verdana;"> determine its minimum column height. A thermal model based on </span><span style="font-family:Verdana;">eulerian-eulerian</span> <span style="font-family:Verdana;">two</span></span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">phase</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> solid-gas theory was performed and solved with the method of lines. </span><span style="font-family:Verdana;">In addition</span><span style="font-family:Verdana;">, this study allows </span><span style="font-family:Verdana;">to investigate</span><span style="font-family:Verdana;"> the effect of the biomass particle size on the minimum </span><span style="font-family:Verdana;">torrefier</span><span style="font-family:Verdana;"> column height. This</span></span><span style="font-family:Verdana;"> investigation </span><span style="font-family:Verdana;">was performed by changing, simultaneously, the diameter of particles and the minimum fluidization velocity of the bed. Then, the calculations were made for a counter-current torrefaction reactor of 30</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">cm in diameter and </span><span style="font-family:Verdana;">for</span><span style="font-family:Verdana;"> 5</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">kg/h of the feed rate of raw sugarcane bagasse.</span><span style="font-family:Verdana;"> Results show that the height of the reactor column must be at least 30 cm for that are 1 mm in diameter and 108 cm for particles that are 2 mm in diameter.</span>
