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Table of Content
25 June 2000, Volume 51 Issue 3
    化工学报
    TRANSIENT RESPONSE STUDIES IN n-BUTANE SELECTIVE OXIDATION TO MALEIC ANHYDRIDE ON A VPO CATALYST
    Huang Xiaofeng, Chen Biaohua, Zhao Bangrong *,Li Chengyue (College of Chemical Engineering, College of Material Science and Engineering, Beijing University of Chemical Technology, Beijing 100029,China)
    2000, 51(3):  293-294. 
    Abstract ( 469 )   PDF (238KB) ( 123 )  
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    PERIODIC OPERATION PERFORMANCE OF FIXED-BED REACTORS FOR SELECTIVE OXIDATION OF n-BUTANE TO MALEIC ANHYDRIDE
    Huang Xiaofeng, Chen Biaohua, Yang Donghaiand Li Chengyue (College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029,China)
    2000, 51(3):  295-296. 
    Abstract ( 553 )   PDF (212KB) ( 91 )  
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    THREE DIMENSIONAL NUMERICAL SIMULATION OF FLUID FLOW AND HEAT TRANSFER IN SHELL-AND-TUBE HEAT EXCHANGER 
    Huang Xinghua 1 ,Wang Qijie 2,Lu Zhen 1 (1 Refrigeration Engineering Research Center, Shanghai Jiao Tong University, Shanghai?200030; 2 Department of Thermal Power Engineering, Shanghai Institute of Electric Power, Shanghai?200090)
    2000, 51(3):  297-302. 
    Abstract ( 743 )   PDF (688KB) ( 406 )  
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    A three dimensional thermal-hydraulic model is developed for the analysis of fluid flow and heat transfer in shell-and-tube heat exchanger. The numerical model uses the distributed resistance model and distributed heat source model along with the concept of porosity, surface permeability to account for the presence of tubes, flow baffles etc in shell side. The volume average conservation equations of mass, momentum and energy of shell side fluid are solved in primitive variable form by using a semi-implicit consistent control-volume formulation in which a segregated pressure correction linked algorithm is employed. The analytical model is validated by comparison of computed pressure drop and temperature distribution with experimental data.
    WALL TRANSFER OF A GAS PLUG RISING IN A VERTICAL SHORT TUBE
    Ming Pingwen and Shen Ziqiu (Department of Chemical Engineering, Dalian University of Technology, Dalian?116012)
    2000, 51(3):  303-307. 
    Abstract ( 670 )   PDF (666KB) ( 99 )  
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    Instantaneous wall transfer of a gas plug rising in a vertical short tube is measured by using electrochemical method. Compared to the results based on hydrodynamic models of developed slug flow, plug rising in a short tube is under an undeveloped condition; wall stress and Sh number follow an analogous pattern, whose minimum appears at the nose and maximum appears at the bottom of gas plug. Wall stress and Sh number in falling film agree with model prediction developed by Zhang.A profile of momentum and concentration boundary layer in liquid slug is presented in this paper, which shows that falling film has little influence on wall mass transfer has significant influence on wall stress.
    NUMERICAL CALCULATION OF THERMAL RESIDUAL STRESS OF INJECTION MOLDED PARTS
    Li Haimei  and Gu Yuanxian Shen Changyu (State Key Laboratory of Structural Analysis (National Engineering Research Center of Polymer of Industrial Equipment,Dalian University and Rubber M
    2000, 51(3):  308-312. 
    Abstract ( 780 )   PDF (589KB) ( 147 )  
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    There are two kinds residual stress of injection molded parts,flow residual stress and thermal residual stress.A numerical simulation model for predicting thermal residual stress which arises during the injection molding of thermoplastic polymer in the cooling stage is developed in this thesis.The temperature field is already calculated while calculating residual stress.The cooling polymer behaves as an isotropic thermorheologically simple solid,and a fully time-dependent algorithm is based on the calculation of the elastic response at each time step.The recurrence formulae for calculating time-dependence stress of two-dimensional integral thermoviscoelastic constitutive equations are established,and then FEM formulae can be derived.The finite element method employed is based on the theory of shell as an assembly of flat elements.This method is well suited for thin injection molded products of a complex shape.A calculation example is given,while considering the effects of cooling efficiency and resin melt temperature.The predicted residual stress by the method used in this thesis agrees with the literature data.
    INQUIRY INTO MECHANISM OF FDP ACCUMULATING USING MODEL OF METABOLIC PATHWAY FLUX
    Ying Hanjie  and Ouyang Pingkai (Department of Biotechnology and Bioengineering,Nanjing University of Chemical Technology, Nanjing?210009)
    2000, 51(3):  313-319. 
    Abstract ( 706 )   PDF (914KB) ( 241 )  
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    In this paper the model of metabolic pathway flux of FDP accumulation is established and the metabolic flux distributions are obtained at different times of FDP accumulation process.The experiments have showed that FDP accumulation in the medium produced by the present method is due to the redirected flux distributions in this metabolic pathway.The yield of FDP to glucose was only 16.1%.Meanwhile,the results also showed that such metabolic flux alterations at key branch points are often directly opposed by mechanisms for controlling enzyme activity,such as HK,PFK,PK, et al ,which have evolved to maintain flux distributions that are optimal for growth.So,in order to overproduce FDP with yeasts,enzyme amplification or other modifications of the product pathway must be done to alter the metabolic flux distributions at the key branch points.
    MATHEMATICAL SIMULATION OF OIL-CONTAINING WASTE WATER TREATMENT BY LOW-PRESSURE HOLLOW-FIBER ULTRAFILTRATION MEMBRANE
    Dong Shengxiong  and Zhang Jiyu (Department of Chemical Engineering , Fuzhou University, Fuzhou?350002)
    2000, 51(3):  320-325. 
    Abstract ( 675 )   PDF (804KB) ( 129 )  
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    A new mass transfer model for oil-containing waste water treatment by low-pressure hollow-fiber ultrafiltration (HFUF) membrane was developed, which considered the axial variation of pressure and local permeation rate since they appeared obviously along the axial distance under low-pressure conditions in practical HFUF process. The numerical simulation was performed by using the orthogonal collocation method (OCM) which was combined with MATLAB software. The predicted results and linear relationship of total permeation rate with inlet pressure, simulated by this model, were in perfect agreement with the experimental data from this study, which proved the rationality of the model and the reliability of the computing method. The simulation showed that radial Peclet number, representing the influence of membrane configuration, solution properties and fluid movement on HFUF process, affected distinctly the radial and axial profile of local or mixing-up concentration. The radial velocity inside the hollow-fiber had a maximum value because of an opposite interaction between the pressure driving force from hollow-fiber center to membrane wall and the diffusion behavior due to the reversed concentration gradient. The average permeation rate decreased with the increase of the axial distance, therefore the final hollow-fiber length would depend on UF efficiency and membrane module cost. Also, the combination algorithm of OCM and MATLAB software displayed its evident advantages of less computer memory space and CPU time. It might be said that the model and the whole simulation software could be employed to provide a suitable selection of HFUF membrane type and technological conditions in both engineering design and actual operation.
    TWO-DIMENSIONAL MASS TRANSFER-MIXING UNIT MODEL IN SPRAY REGIME
    Guo Yanshu  Liu Jincheng (Department of Chemical Equipment and Control Engineering, (Separation Column Research Institute, Hebei University of Science and Technology,Shijiazhuang?050018) CNFIA,Shij
    2000, 51(3):  326-330. 
    Abstract ( 525 )   PDF (570KB) ( 97 )  
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    A two-dimensional mass transfer-mixing unit model for tray efficiency in the spray regime was proposed in this paper. By means of this model, the influence of the parameters such as single unit drag-up,inter-unit exchange fraction and circulating fraction of liquid on tray efficiency can be easily simulated. It provides a theoretical basis for the development and design of trays operating in the spray regime.
    IMPACT OF PERIODIC SIGNAL ON DELAY TIME OF RECONSTRUCTED DYNAMIC IN FLUIDIZED BED
    Zhao Guibing  , Shi Yanfu, Guan Guoqing, Zhou Yong and Yu Huarui (School of Chemical Engineering, Sichuan University, Chengdu 610065)
    2000, 51(3):  331-337. 
    Abstract ( 564 )   PDF (921KB) ( 107 )  
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    The first task of applying deterministic chaos theory to studying the dynamics of fluidized bed from the time series of pressure fluctuation is the computation of delay time of reconstructed phase space. This paper studies the influence of periodic and stochastic signal on the computation. It is suggested that the periodic components that possibly exist in the measured instantaneous pressure could make the delay time correspond to the first minimum of mutual information increase, such as the result of Dow and Halow [6] .A method of extracting periodic tendency term from the instantaneous pressure signal and its statistics test are provided. After removing periodic components from the original signal, the delay time that corresponds to the first minimum of mutual information can be determined correctly.
    CHAOS BUBBLING IN GAS-LIQUID TWO-PHASE BUBBLE COLUMN WITH A SINGLE ORIFICE
    Liu Mingyan and Hu Zongding (College of Chemical Engineering,Tianjin University,Tianjin?300072)
    2000, 51(3):  338-343. 
    Abstract ( 596 )   PDF (718KB) ( 172 )  
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    The chaotic bubbling mechanism in the gas-liquid two-phase bubble column with a single orifice was studied using the deterministic chaos analysis technique.It was found that when the values of gas flow rate was low,the stages of period icity and quasiperiodicity could be clearly identified.And when increasing gas flow rate,the sequence led to chaotic behavior.The bubbling process had three different flow regimes with the increase of gas flow rate:periodic bubbling regime,chaotic bubbling regime and jetting bubbling regime.
    COMPUTATIONAL FLUID DYNAMIC MODELING OF HYDRODYNAMICS IN DOWNER REACTORS
    Cheng Yi,Wei Fei,Zheng Yu and Jin Yong Guo Yincheng and Lin Wenyi (Department of Chemical Engineering, (Department of Engineering Mechanics, Tsinghua University, Beijing?100084) Ts
    2000, 51(3):  344-352. 
    Abstract ( 821 )   PDF (990KB) ( 182 )  
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    On the basis of kinetic theory of particulate phase, a k-ε-Θ-k p model was derived by Reynolds averaging procedure on the laminar gas-solid CFD model.The gas phase was described by a standard k-ε turbulence model and the solid phase was described by the kinetic theory and k p turbulence model. This k-ε-Θ-k p model took into account the contribution of both particle collisions and particle turbulence to momentum and energy transportation. A three dimensional CFD code was developed to simulate the gas-solid flow in a downer reactor, which is 0.14 m in radius and 7 m in height. An important modification of restitution coefficient, e , was made to consider the wall effect on the two-phase flow. Three kinds of models were discussed and compared from the point of view of physical mechanism. The k-ε-Θ-k p model was used to predict the distributions of solids fraction, particle/gas velocity and pressure. The model predictions agreed well with the experimental data in the wide range of operating conditions. The characteristics of scaling-up of downers were also predicted and the results seemed encouraging.
    TRANSIENT AND TIME-AVERAGED OSCILLATORY HEAT TRANSFER OF TWO-PHASE FLOW DURING SECOND REGIONAL PRESSURE-DROP OSCILLATION IN HELICAL COILED TUBE
    Feng Ziping and Guo Liejin  (State Key Laboratory of Multiphase Flow in Power Engineering,Xian Jiaotong University,Xian?710049)
    2000, 51(3):  353-357. 
    Abstract ( 655 )   PDF (668KB) ( 112 )  
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    On the basis of the classification and definitions of two regions of pressure drop oscillation in our previous work, the transient and time-averaged heat transfer characteristics of steam-water two-phase flow during the second regional pressure drop oscillation were experimentally studied in a closed circulation system with a helical coiled tube boiling channel. New non-dimensional parameters and criterion for characterizing the effects of second regional pressure drop oscillation on transient and time-averaged heat transfer coefficient were proposed.
    CONDENSATION IN THREE-DIMENSIONAL MICRO-FIN TUBE FOR HFC-134a
    Xin Mingdao ,Chen Qinghua,Cui Wenzhi,Zhou Jie and Zhang Gang (Institute of Engineering Thermophysics,Chongqing University, Chongqing?400044)
    2000, 51(3):  358-361. 
    Abstract ( 650 )   PDF (530KB) ( 170 )  
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    Microfin tube is one of the most popular enhancements for in-tube boiling and condensation of refrigerants. The reason for its popularity is the larger heat transfer enhancement relative to the slightly increased pressure drop. Because of its outstanding performance, it has strongly attracted the attention of a large number of investigators, and numerous papers have been published on microfin tubes [1~3] .However, almost all microfin tubes studied by those investigators were single helix (2-D) microfin geometry. A new 3-D microfin tube was first developed by Du and Xin, et al . (1995). Their 3-D microfin tube is seamless. Xin and Wang had studied the in-tube condensation heat transfer performance of the 3-D microfin tube with R-11 and steam. In 1996, Chamra and Webb et al . presented another 3-D microfin tube, which were manufactured by using high frequency welding method. They reported the condensation performance with refrigerant R22. The experimental data of the two 3-D microfin tubes in their papers demonstrated higher heat transfer performances as compared with 2-D micro-fin tubes. However, no one reported the refrigerant R134a condensation performance in 3-D microfin tube. The purpose of this paper focuses on the condensation performance for refrigerant R134a in a new 3-D micro -fin tube. The experiments are carried out at different inlet pressure: 0.51-0.77 MPa ( temperature: 18 - 30 ℃), the mass flux is between 125 and 285 kg/m 2·s, and the vapor quality, x , is from 1.00 to 0.14. The data are compared with those of smooth tube, which are calculated with Shahs correlation. The ratio of enhancement for condensation is 1.7-3 (at x =0.6) in the experimental range of the mass flux noted above. The average ratio of enhancement is 2.2. The effects of mass flux and quality are also reported.
    PHASE INVERSION DURING BULK COPOLYMERIZATION OF N -PHENYLMALEIMIDE/STYRENE IN PRESENCE OF POLYBUTADIENE(Ⅰ) CHANGES OF PHYSICAL CHARACTERISTICS OF COPOLYMERIZING SYSTEM DURING PHASE INVERSION
    Chen Yuan, Li Baofang, Cao Kun and Li Bogeng ** (State Key Laboratory of Polymer Reaction Engineering, Department of Chemical Engineering, Zhejiang University, Hangzhou?310027)
    2000, 51(3):  362-366. 
    Abstract ( 551 )   PDF (590KB) ( 105 )  
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    The semi-continuous bulk copolymerization of N -phenylmaleimide and styrene was carried out in the presence of polybutadiene(PB). The phase inversion, refractive index and the rheological behavior of the polymerizing mass, and the grafting ratio of N -phenylmaleimide-styrene copolymer onto PB in the course of polymerization were investigated. The results indicated that the phase inversion occurred in a relatively wide range of time. In the phase inversion region, the refractive index changed irregularly and the grafting ratio increased sharply, while the viscosity of the polymerizing mass declined.On-line monitoring of agitating torque for the reactor is very useful to identify the region of phase inversion.
    RADICAL POLYMERIZATION OF N -VINYLPYRROLIDONE IN SOLUTION
    Cui Yingde  , Yi Guobin , Liao Liewen and Kang Zheng (Department of Chemical Engineering,Guangdong University of Technology, Guangzhou?510090)
    2000, 51(3):  367-371. 
    Abstract ( 609 )   PDF (728KB) ( 174 )  
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    In this paper,the influences of solvents, monomer conncentration and initiator concentration on radical polymerization of N -vinylpyrrolidone(NVP) are investigated. Especially, benzene, ethanol, distilled water are experimented as solvents to investigate the influences of solvent polarities, viscosities of mixture of monomer and solvent on polymerization rate, chain propagation rate and relative molecular mass of polyvinylpyrrolidone. Furthermore, crosslinking polymerization properties of N -vinylpyrrolidone and N,N - methylenebisacrylamine(NNMP) are studied. It is found that a higher yield of crosslinking polyvinylpyrrolidone(PVPP) can be obtained in a aqueous solution of some inorganic salt. Some explanations are presented.
    WAVELETS BASED MRA OF PROCESS DATA PROCESSING
    Jiang Taiwen  ,Chen Bingzhen and He Xiaorong (Department of Chemical Engineering, Tsinghua University, Beijing 100084)
    2000, 51(3):  372-377. 
    Abstract ( 597 )   PDF (768KB) ( 255 )  
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    Considering the non-stationary nature of chemical process, this paper presents a multi-resolution analysis (MRA) methodology for data processing. It is based on the time-frequency localization of wavelet analysis, which can extract temporal features localized in both frequency domain and time domain of process signal. In this algorithm, multi-scale wavelet transform (WT) of the process data is made, and the process data is decomposed into scaled signal and detail signal on each scale. According to their unique characteristics created by WT in the detail signals across time or scale, different variations are identified, such as steps, peaks, and noises. Especially, abnormal sudden changes, which are the most harmful temporal features to process analysis, are detected from a couple of WT modulus maxima with abnormal large amplitudes. With different variations modified with appropriate strategies, process data are reconstructed from the modified scaled signals and detail signals. It is a close approximation of the original process data, with noises discarded and abnormal sudden changes treated effectively, which traditional Fourier Transform of filtering is powerless to do. Using this method, the real process trends are extracted from the raw process data correctly. It is a powerful tool for dynamic process trends analysis, such as process steady state detection, faults diagnosis on-line and real time detection of gross errors in dynamic process data. This method has been applied to processing practical data of crude oil distillation plant. The result shows that the method is essential and effective for process trends analysis and treatment on-line.
    BACK-PROPAGATION NEURAL NETWORK MODEL OF DYNAMIC SYSTEM AND ITS APPLICATION
    Wu Jianfeng,He Xiaorong and Chen Bingzhen (Department of Chemical Engineering,Tsinghua University,Beijing?100084)
    2000, 51(3):  378-382. 
    Abstract ( 770 )   PDF (612KB) ( 162 )  
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    The artificial neural networks are now being widely studied and used in many fields because of their high capability of mapping the input-output relationship of nonlinear systems.However,for nonlinear dynamic systems,such as the fractionating equipment of refinery,the standard back-propagation(BP) neural network——which is the most often studied and used,can not perform very well when used to model these systems,especially when they are not in steady states.So,in this paper,a new structure of feed forward neural network named dynamic back propagation neural network(DBPNN),based on back propagation algorithm and time series model is presented.The DBPNN can be used to model dynamic nonlinear systems.Furthermore,with the special structure of the integrated node layer,the complexity of the DBPNN is largely reduced.By using data from laboratory model and data from the fractionating equipment of some refinery,DBPNN models are built.The result shows that the DBPNN models can identify the dynamic behavior of nonlinear dynamic systems and are more accurate and reliable,compared with the result of models of these two nonlinear dynamic systems using standard back propagation neural networks.
    ENERGY CONSERVATION OF IMPROVED CRUDE DISTILLATION PROCESS
    Wang Lin, Duan Zhanting and Zhou Rongqi  ( Department of Chemical Engineering,Tsinghua University, Beijing?100084 )
    2000, 51(3):  383-389. 
    Abstract ( 563 )   PDF (785KB) ( 115 )  
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    In this paper,an improved crude oil distillation process is presented and simulated by PRO/II. The calculation results indicate that given the heat exchange satisfaction of demand the atmospheric still of the new process can save energy by 18.3%, while maintaining a higher distil-off ratio than the traditional on by 0.9%. Additionally, by applying deep distil-off section to the vacuum column, the distil-off ratio can be raised by 0.46% with the same energy consumption. A heat exchanger network for the new process is designed by threshold method and simulated. The calculation results confirm the former assumption about heat exchange objective and the energy conservation effect of the new process.
    NEW METHOD OF REDUNDANCY ANALYSIS IN DATA RECONCILIATION
    Zhang Puming,Rong Gang ,Wang Xiuping and Wang Shuqing (National Key Laboratory of Industrial Control Technology, Zhejiang University, Hangzhou?310027)
    2000, 51(3):  390-394. 
    Abstract ( 697 )   PDF (513KB) ( 105 )  
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    In data reconciliation, it is common practice to detect gross errors and delete those measurements with gross error(MGEs) before using the algorithm of reconciliation. Each measurements deletion affects the structure of measurement network as well as reconciliation precision. Since some MGEs deletion will perhaps result in the unreasonable solution of the least squares algorithm of data reconciliation, MGEs can not be deleted totally at one time. They must be treated differently in order to delete as many MGEs as possible to ensure reconciliation precision. To solve this problem, a new method of redundancy analysis is proposed in this paper. Supposing one MGE is deleted and treated as unmeasured variable, the corresponding formulation of the data reconciliation problem is adjusted and its reconciliation precision can be calculated. Thereupon, the first order redundancy degree of the deleted MGE is defined. After all of the MGEs are checked, the MGE with the largest first order redundancy degree will be deleted and treated as unmeasured. In the same way, the higher order redundancy degree of the remained MGEs can be calculated, and they can be removed one by one until the deletion of each one left will lead to no redundancy of the network. In this way, the information in the data can be used sufficiently and the reconciliation precision is ensured. Simulation result demonstrates the efficiency of the proposed method.
    FLUID DYNAMICS CHARACTERISTICS OF TYPE-95 TRAY WITH A NEW STRUCTURE
    Guo Minqiang, Li Peng, Wu Youting, Xiao Jian  and Zhang Zhibing (Department of Chemical Engineering, Nanjing University, Nanjing?210093)
    2000, 51(3):  395-398. 
    Abstract ( 608 )   PDF (436KB) ( 172 )  
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    A new type of tray called Type-95 tray with a bigger effective mass transfer area and higher tray efficiency is developed and tested, whose downcomer structure is specially designed with a new concept. The fluid dynamics characteristics of the tray, i.e., pressure drop, weeping, liquid height in the downcomer and flow pattern on the tray, are determined on a test rig with a diameter of 1000 mm by air-water system at atmospheric pressure. The experimental results are compared with those of the traditional sieve tray. It indicates that the Type-95 tray has the advantage of lower pressure drop and bigger flux. The related mathematical equations for designing Type-95 tray are derived from the experimental data, which can be basically applied to the design of an industrial tray within allowable engineering deviation. In addition, the eddy and backmixing of liquid on the tray can be eliminated effectively by installing appropriate deflectors. As a result, the liquid flow pattern on the tray is almost changed into plug flow, which might cause an increase of mass transfer efficiency of the tray.
    MODIFIED ROTATING DISK CONTACTOR
    Qi Mingzhai  (Department of Chemical Engineering,East China University of Science and Technology,Shanghai?200237)Dai Jie (Research Institute of Nanjing Chemical Plant, Nanjing?210038)
    2000, 51(3):  399-402. 
    Abstract ( 597 )   PDF (455KB) ( 143 )  
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    A new type of modified extraction equipment——CTRDC(rotating disk contactor with closed turbine)has been developed.The experimental results of hydrodynamics and mass transfer in CTRDC show that the rotor speed required for satisfactory dispersion could decrease sharply with more uniform axial d p distribution.Compared with RDC,CTRDC offers better performance,such as throughput and efficiency.The experimental results can serve as a reference for scale up design and operation optimization.
    TRANSPORT CHARACTERISTICS OF ALBUMIN-FILLED POROUS MEMBRANE FOR REMOVAL OF LIPOPHILIC TOXINS
    Zhang Guoliang  ,Zhang Zhiping,Zhang Fengbao and Shi Wei (School of Chemical Engineering and Technology,Tianjin University,Tianjin?300072)
    2000, 51(3):  403-406. 
    Abstract ( 479 )   PDF (418KB) ( 102 )  
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    The removal of protein bound substances from blood is of therapeutic interest for drug intoxications,renal and liver failure,and so on.Current methods using hemoperfusion over adsorbents or plasma exchange are effective but not specific enough.This work presents a new procedure in which an albumin (BSA) filled porous asymmetric membrane with a high permeable flux is prepared and used for the removal of lipophilic toxins (unconjugated bilirubin) from blood.The transport mechanism of the membrane to remove protein bound toxins is analysed.The transport characteristics of the BSA filled membrane are tested by using aqueous BSA solution containing unconjugated bilirubin as simulated blood in a diffusion cell.In addition,some factors affecting transport rate are discussed.It concludes that the present method provides a theoretical basis for treatment of acute liver failure as well as acute or chronic intoxications with alburnin bound toxins.
    PREDICTION OF INTERNAL PRESSURE AND VALUES OF NEW SOLUBILITY PARAMETER FOR LIQUIDS
    Xu Yunlei, Yu Chunfang, Hei Encheng and Liu Guojie  (Department of Chemistry , East China University of Science & Technology , Shanghai?200237)
    2000, 51(3):  407-413. 
    Abstract ( 566 )   PDF (546KB) ( 172 )  
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    The modified van der Waalsmodel which has only one molecular size-dependent parameter is used to calculate the internal pressures of liquids.It is found that the model parameter has very good linear relation with the molar volume of liquids at normal boiling point.A group contribution method is established for the molar volume of liquids at normal boiling point.Therefore the internal pressures of various liquids can be predicted.On the basis of the generalized Gibbs free energy model for mixing of liquids,proposed by our previous work,a new solubility parameter had been defined,which is equal to the ratio of the cohesive energy density with the square root of internal pressure.This definition is more strict and its range of application is more exten sive than classical Hildebrand solubility parameter.In present work,the values of new solubility parameter for 170 solvents at 298.15 K are obtained.
    NUMERICAL SIMULATION OF GRINDING CHAMBER IN A PANCAKE SUPERFINE JET MILL
    Liu Xuedong and Zhuo Zhen (Department of Mechanical Engineering,Jiangsu Institute of Petrochemical Technology, Changzhou?213016)
    2000, 51(3):  414-417. 
    Abstract ( 496 )   PDF (526KB) ( 92 )  
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    In this paper the commercial software PHOENICS(v1.5) is used to simulate the turbulent flow in the grinding chamber of a pancake superfine jet mill. The predicted results of 3-D velocity fields and velocity vectographs are given. LDV measurements are made to validate the results predicted by PHOENICS. The predicted results show that the tangential velocities are the main components, the radial velocities are directed to the wall of chamber near the nozzles, the axial velocities are small but can not be neglected. The method of numerical simulation will improve the design of pancake superfine jet mill.
    SOLVENT EXTRACTION OF EPHEDRINE EPIMERIDES WITH CHIRAL AGENTS
    Cen Zhongzhe and Cai Shuihong (School of Chemical Engineering, East China University of Science and Technology, Shanghai?200237)
    2000, 51(3):  418-420. 
    Abstract ( 828 )   PDF (445KB) ( 290 )  
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    In this work six kinds of tartrate diesters were prepared from D(-), L(+) or DL-tartaric acid respectively, and their structure were verified by IR and NMR. The extraction behavior of optical compounds, D(-) ephedrine and L(+) pseudoephedrine, was investigated at room temperature using prepared tartrate diester as extracting agent and n -heptane as diluent. The ratio of tartrate diester and n -heptane is 1∶1. Distribution coefficients, obtained from experiment data by material balance, show that there is a chiral recognition: L(+) tartrate diesters favour extraction of L(+) pseudoephedrine,while D(-) tartrate diesters favour extraction of D(-) ephedrine. The extraction behavior of the mixture of the above optical active epimerides, was also investigated under the same experimental conditions. The experiment data with HPLC also showed the same conclusion. Meanwhile, a blank experiment was carried out and the result showed that there was no evident effect on extraction distribution coefficients when extraction process occurred in the presence of n -heptane. The relationship between the structure of extracting agent and optical activity of the epimerides was also discussed.
    PRINCIPIUM DESIGN OF IDEAL INTERNAL THERMALLY COUPLED DISTILLATION COLUMNS (I) MODELING AND OPERATION BEHAVIOR
    Liu Xinggao and Qian Jixin (Institute of Industrial Process Control and National Laboratory of Industrial Control Technology, Zhejiang University, Hangzhou?310027)
    2000, 51(3):  421-424. 
    Abstract ( 688 )   PDF (439KB) ( 114 )  
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    Internal Thermally Coupled Distillation Column(ITCDIC) is the research frontier of distillation energy saving . This paper investigates the principium design of ideal ITCDIC. A novel design model of ideal ITCDIC is derived, which can not only directly achieve the system characteristics and comparative characteristics with conventional distillation columns, but also be used for further control and design studies. A series of detailed operation analyses are carried out, which pave the way for further research and practice application.
    PRINCIPIUM DESIGN OF IDEAL INTERNAL THERMALLY COUPLED DISTILLATION COLUMNS (II) CONTROL ANALYSIS AND PARAMETER OPTIMIZATION
    Liu Xinggao and Qian Jixin (Institute of Industrial Process Control and National Laboratory of Industrial Control Technology, Zhejiang University, Hangzhou?310027)
    2000, 51(3):  425-428. 
    Abstract ( 678 )   PDF (439KB) ( 120 )  
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    Based on the previous design model, degrees of freedom analysis and transient analysis are carried out. A PID control model is proposed. The results show that ITCDIC is a self-regulating process, and could be operated smoothly with two PID controllers; the steady state design could be disassociate with the dynamic design. An optimization model of ITCDIC design parameters is derived, which can directly achieve the optimal design parameters providing the maximum energy savings and the product quality simultaneously. Benzene-toluene system is studied as an illustrative example.
    INFLUENCE OF PACKING PLATE DISTANCE OF HIGH-GRAVITY ROTATING BED ON GAS PHASE RESISTANCE
    Jian Qifei,Deng Xianhe,Zhang Yajun,Chen Haihui and Deng Songjiu (Heat Transfer and Energy Conservation open Lab of Education Ministry South China University of Technology,Guangzhou?510640)
    2000, 51(3):  429-433. 
    Abstract ( 631 )   PDF (520KB) ( 225 )  
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    The relationship between gas pressure drop and gas resistance coefficient versus operation condition and gas phase Reynolds number in three packing plate distance was theoretically analyzed and experimentally measured in the centrifugal field.The experimental results show that packing plate distance has a great influence on gas phase resistance and too small distance makes liquid clogging and causes great gas phase resistance.The fitness distance of the packing plate is large than 3.1 mm under the operation condition in this paper.