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Table of Content
25 August 1995, Volume 46 Issue 4
    化工学报
    PHASE EQUILIBRIA AND RADIAL DISTRIBUTION FUNCTION (Ⅰ) MASS FLUX CRITERION FOR PHASE EQUILIBRIA
    Chen Guangjin. Wu Jinyuan and Yu Guocung (K. T. Yu)(Chemical Engineering Research Centre of Tianjin University, Tianjin 300072)
    1995, 46(4):  393-397. 
    Abstract ( 834 )   PDF (234KB) ( 154 )  
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    A physical model, named "double -resistance model", was proposed to describe the transfer of molecules between two adjacent phases. Based on this model, the equation for the calculation of mass flux was derived. Instead of chemical potential criterion, mass flux criterion was suggested and the relationship of the densities of two phases was obtained when they were in equilibrium. This relationship was used to predict the vapor pressure of pure liquids and good results were obtained.
    PHASE EQUILIBRIA AND RADIAL DISTRIBUTION FUNCTION (Ⅱ) MICRO-PHASE EQUILIBRIA METHOD FOR CALCULATING RADIAL DISTRIBUTION FUNCTION
    Chen Guangjin, Wu Jinyuan and Yu Guocung (K. T. Yu)(Chemical Engineering Research Centre of Tianjin University,Tianjin 300072)
    1995, 46(4):  398-402. 
    Abstract ( 745 )   PDF (220KB) ( 117 )  
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    Based on the double - resistance model and mass flux criterion proposed in part (Ⅰ) of this paper and by considering the phase equilibria between any one micro -phase and disorder space, the radial distribution function was expressed analytically in terms of local capture probability and local potential energy. The methods for calculating local capture probability and local potential energy were given. Because of the analyticity of the equations for calculating radial distribution function, much less computation time was needed than integral equation methods or molecular simulations. The results were in good agreement with those from molecular simulations. Better results were obtained than integral equations near the first peak.
    SIGMOIDAL - QUADRATIC BASIS FUNCTION NETWORK FOR IMPROVING THE BOUNDING CAPABILITY OF FAULT SPACES
    Zhao Xiaoguang, Chen Bingzhen and He Xiaorong(Department of Chemical Engineering ,Tsinghua University , Beijing 100084)
    1995, 46(4):  403-409. 
    Abstract ( 598 )   PDF (364KB) ( 85 )  
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    According to the characteristics and requirements of fault diagnosis in process systems and based on the previous work, this paper puts forward a Sigmoidal - Quadratic Basis Function Network (SQBFN) which can improve the bounding capability of fault space. This netv/ork first divides the input space by quadratic hypersurfaces and then exactly describes the regions of faults in fault space through complicated decision space formed by the superposition of those hypersurfaces. SQBFN is of powerful classification, good flexibility and may form the required closed or semi - closed decision spaces avoiding arbitrarily dividing blank spaces. This paper gives an introduction to SQBFN and verifies its effectiveness by two examples. The results of theoretical analysis and researches on examples indicate that the bounding capability of SQBFN is superior to other networks and at the same time its structure is not complicated and even more simple.
    STUDY OF DECOLORIZATION OF ANIONIC DYES BY USING CATIONIC POLYMER
    Fang Daobin, Zhou Shaogang and Guo Ruiwei(Department of Applied Chemistry ,Tianjin University,Tianjin 300072)
    1995, 46(4):  410-415. 
    Abstract ( 651 )   PDF (273KB) ( 192 )  
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    This paper deals with decolorization of anionic dyes, Methyl Orange, Acid Red 3BM and Mordant Blue I, by using poly(2-trimethylammoniumethyl methacrylate chloride) (PTMAC) with varying relative molecular mass and cationic ionization degree. The results show that both the relative molecular mass and cationic ionization degree of PTMAC and cationic group concentration will affect decolorization, while the decolorization rate relates to intensity and wave -length of absorption peak. Besides, the decolorization mechanism is discussed as well.
    MODELING OF UNSTEADY-STATE OXIDATION PROCESS OF SO_2 (Ⅰ) AXIAL HEAT TRANSFER OF FIXED-BED PACKED WITH VANADIUM CATALYST
    Wu Huixiong, Zhang Shuzeng, Li Chengyue and Fu Jufu{Department of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029)
    1995, 46(4):  416-423. 
    Abstract ( 712 )   PDF (377KB) ( 127 )  
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    By applying the technique of pulse thermal input, the axial heat transfer of a fixed -bed packed with vanadium catalyst was investigated under the conditions that the initial temperature ranged from room temperature to about 500℃, and Re=30~660. It was shown that the correlations for calculating ke,ax and hp presented by Wakao are still applicable to the cases studied here at an average bed temperature under 200℃ but the values of axial thermal conductivity at about 500℃ are higher than those predicted previously.
    MODELING OF UNSTEADY-STATE OXIDATION PROCESS OF SO_2 (Ⅱ) MODEL SIMULATION AND PARAMETER ANALYSIS
    Zhang Shuzeng. Wu Huixiong and Li Chengyue(Department of Chemical Engineering,Beijing University of Chemical Technology, Beijing 100029)
    1995, 46(4):  424-430. 
    Abstract ( 625 )   PDF (359KB) ( 122 )  
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    The heterogeneous transient model of a fixed - bed reactor packed with vanadium catalyst, S101, for catalytic oxidation of SO2 and operating in a flow direction switched periodically was developed. Computation results showed that autothermal oxidation of low concentration SO2 is feasible. The effects of important parameters on the performances of the reactor operating in this mode were numerically studied. It is noticed that time averaged conversion and temperature at the hot - spot are rather sensitive to the variation of the composition and flow rate of feed. This qualitative conclusion should be considered in the design of a commercial reactor in order to keep stable operation.
    HOMOTOPY CONTINUATION METHODS FOR COMPLEX DISTILLATION PROCESSES (Ⅰ) MODEL AND ALGORITHM
    Zhou Aiyue, Liu Cheng and Chen Hongfang(Department of Chemical Engineering,Tianjin University,Tianjin 300072)
    1995, 46(4):  431-438. 
    Abstract ( 685 )   PDF (327KB) ( 253 )  
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    A generalized model for complex distillation processes, which taking into account both multiphase (two liquid phases) and reaction on the trays is presented in this paper. The algorithm is worked out with globally convergent Newton homotopy continuation method for solving highly nonlinear systems. The algorithm for the calculation of liquid -liquid equilibria is featured by convergence, rapidity and reliability.
    HOMOTOPY CONTINUATION METHODS FOR COMPLEX DISTILLATION PROCESSES (Ⅱ) SIMULATION EXAMPLES
    Zhou Aiyue. Liu Cheng and Chen Hongfang(Department of Chemical Engineering < Tianjin University, Tianjin 300072)
    1995, 46(4):  439-445. 
    Abstract ( 704 )   PDF (334KB) ( 131 )  
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    Three processes of complex distillation are simulated using the Newton homotopy continuation method in this article. They are; (1) the dehydration of ethanol with benzene -five steady - state solutions under the same specifications from just one starting point; (2) three phase distillation for five components; (3) three phase reaction distillation for five components. The selection of the parameters for controlling the step size has been investigated under different cases for each problem. The facts of rapid convergence from any one starting point show that the algorithm is more robust. The results of simulations are in good agreement with the references and industrial experiments.
    NUMERICAL SIMULATION OF FLOW AND HEAT TRANSFER IN NATURAL GAS WELL BORE
    Zhu Huiren and Liu Songling(Department of Aeroengine and Thermal PowerEngineering, Northwestern PolytechnicalUniversity, Xian 710072 )Wu Gesheng and Zhang Shuping(Drilling and Production TechnologyResearch Institute of Changqing OilExploration Bureau, Qi
    1995, 46(4):  446-451. 
    Abstract ( 684 )   PDF (262KB) ( 193 )  
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    A model for simulating the flow and heat transfer in natural gas well bore was established by using the basic principle of gas dynamics ,heat transfer and thermodynamics. The predicted results from this model were in good agreement with the measured values. Two heat insulation methods to avoid forming natural gas hydrate which will obstruct the flow of natural gas were discussed. The results showed that in order to increase the exit temperature of natural gas the heat insulaton coating should be applied on the outside of well bore rather than filling nitrogen into the annulus between well bore and casing.
    STUDY ON ADSORPTION THEORY OF VOLUME FILLING OF MICROPORES
    Xie Zili and Guo Kunmin(Research Institute of Chemical Defence,Beijing 100083)
    1995, 46(4):  452-457. 
    Abstract ( 648 )   PDF (297KB) ( 311 )  
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    Based on the theory of volume filling of micropores (TVFM) , an advanced adsorption isotherm equation is presented to describe vapor adsorption on microporous adsorbents. It is found that parameters in the equation individually represent the characteristics of both micropore structure and vapor adsorption. Experimental adsorption isotherms of several organic vapors on several commercial activated carbon are used to verify the equation. The results are satisfactory.
    SIMULATION OF LIQUID CIRCULATION IN BUBBLE COLUMNS
    Luo Hean(Department of Chemical Engineering, Xiang tan University, Xiangtan 411105)Hallvard F. Svendsen(Department of Chemical Engineering,Norwegian Institute of Technology ,7034 Trondheim,Norway)
    1995, 46(4):  458-463. 
    Abstract ( 477 )   PDF (277KB) ( 252 )  
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    A new model describing liquid circulation in bubble column reactors is developed with the concept of seperated flow. The effects of several factors on liquid circulation are simulated with the model. The results show good agreements with the experimental data reported in literature.
    ADSORPTION CHARACTERISTICS OF HEMOPERFUSION PROCESS
    Li Shiyu and Wang Shaoting(Department of Chemical Engineering, Tianjin University, Tianjin 300072)
    1995, 46(4):  464-470. 
    Abstract ( 644 )   PDF (328KB) ( 161 )  
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    The adsorption mechanism of coated activated carbon was analysed and the mathematical model of hemoperfusion process was established. The results of treating 20 groups of data of pig blood perfusion in vitro showed that the calculation values could fit the experimental data well, the adsorption equilibrium could be described as Langmuir equation, the adsorption rate controlling step of creatinine was the outside diffusion, but that of inulin was the inside diffusion or the coordination of both the outside and the inside diffusion. The influence of the ratio of height to diameter on hemoperfusion process was little.
    HYDRODYNAMIC CHARACTERISTICS OF FILM CASTING TO FORM MEMBRANE AND MEMBRANE MORPHOLOGY
    Wang Zhi and Wang Shichang(Chemical Engineering Research Center,Tianjin University,Tianjin 300072)
    1995, 46(4):  471-479. 
    Abstract ( 519 )   PDF (768KB) ( 132 )  
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    On the basis of stability analysis of film casting to form membrane, membrane morphology related to hydrodynamic characteristics of the film was studied by computer simulation. It was pointed out that hydrodynamic instability can result in periodic tinevennesses, aggregates and holes on the membrane surface. The effects of excess intermolecular potential energy gradient, gravity, viscosity and surface tension op membrane structure, and the methods to eliminate these structures were discussed. The schlieren observation of the evaporation step of casting solutions was carried out. It was proved that nonhomogeneous and convective structure resulting from hydrodynamic instability would appear in the casting solution during evaporation. Unevennesses, aggregates and holes on the mumbrane surface were observed by optical microscope ana SEM, which corroborated the results of the theoretical analysis.
    TURBULENCE FLOW PARAMETERS IN STIRRED TANK WITH PROPELLER
    Hou Shuandi, Wang Yingchen and Shi Litian(Department of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029)
    1995, 46(4):  480-486. 
    Abstract ( 577 )   PDF (338KB) ( 95 )  
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    In seven kinds of impeller - tank systems, the characteristics of turbulence flow have been investigated by using a one - dimensional hot - film anemometer. The measured parameters include the mean and fluctuating velocities and energy spectrum. Based on the measured results, the overall flow patterns in the stirred tank are obtained. The effects of the impeller off - bottom - distance, the impeller tip angle and scale - up on the patterns and turbulence parameters have been studied.
    EFFECTS OF CATHODIC POLARIZATION ON CHEMICAL AND ELECTROCHEMICAL STATES INSIDE OCCLUDED CELLS OF LOCALIZED CORROSION OF STAINLESS STEEL
    Liu Youping(Department of Applied Chemistry, Beijing University of Chemical Technology, Beijing 100029)Zhu Rizhang(Department of Surface Science andCorrosion Engineering, University ofScience and Technology, Beijing 100083)
    1995, 46(4):  487-492. 
    Abstract ( 560 )   PDF (322KB) ( 96 )  
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    A simulated galvanostatic occluded cell was used to investigate the effects of cathodic protection on chemical and electrochemical states inside occluded cells of localized corrosion for 1Cr13 and 0Cr18Ni9 stainless steels in 0. 5 mol/L NaCl solution. It was found that solution pH inside occluded cells increased from originally below the critical value to that above it,Cl-1 concentration of the occluded solution decreased by electromigration,and potential of the occluded alloy dropped from "corrosion" zone to "immunity" zone on the potential/ pH diagrams as the cathodic polarization was applied. The mechanism of cathodic protection to stifle pitting or cracking propagation could thus be interpreted.
    RHEOLOGIC PROPERTIES OF FIBER SUSPENSIONS IN VISCOELASTIC FLUID
    Zhou Wei(Department of ChemicalEngineering. Zhejiang University,Hangzhou 310027)Wang Ligang and Fan Xijun(Department of Mechanics,Zhejiang University,Hangzhou 310027)Li Yujing and Chen Yihong(Institute of Chiemistry,Chinese Academy of Sciences,Beijing 100
    1995, 46(4):  493-500. 
    Abstract ( 538 )   PDF (377KB) ( 140 )  
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    This paper describes a constitutive equation for semi - concentrated fiber suspensions in the Oldroyd - B fluid. Fiber orientation and stress growth upon the inception of steady shear flow are calculated. The model predictions are compared to those using other constitutive equations and experimental data. The constitutive equation in this paper can reasonably describe stress growth,especially the viscoelastic stress growth after the initial stress peak value contributed from the fiber component.
    MEASUREMENT OF GAS-LIQUID FLOW .IN DUCT WITH ROUND CYLINDER PRESSURE DROP-TURBINE METER
    Shen Hongmei and Gu Fan(Department of Power Engineering, Southeast University,Nanjing 210018)Zhou Fangde(Thermophysics Institute,Xian Jiaotong University,Xian 710049)
    1995, 46(4):  501-506. 
    Abstract ( 530 )   PDF (298KB) ( 105 )  
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    The paper puts forward a method of combining round cylinder pressure drop - turbine meter for measuring gas - lipuid flow in a duct. The characteristics of this method were investigated in the experiments. By means of computer control,the performance of the experiments with volume fractions β=0. 0,0. 3,0. 5,0. 8 and 1. 0 was measured. Based on the observation and analysis, an equation for the round cylinder pressure drop - turbine meter measurement was developed. A theoretical discussion of the measurement method was presented.
    DETERMINATION OF RATE CONSTANT OF PRIMARY INTRA - CROSSLINKING REACTION IN CROSSLINKING COPOLYMERIZATION
    Luo Yingwu, Weng Zhixue, Huang Zhiming and Pan Zuren(Department Polymer Science and Engineering,Zhejiang University ,Hangzhou 310027)
    1995, 46(4):  507-510. 
    Abstract ( 489 )   PDF (160KB) ( 88 )  
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    Based on the property of intrinsic viscosity of intra - crosslinking polymer, a new method to determine the rate constant of the primary intra - crosslinking reaction was developed in the crosslinking copolymerization. Furthrmore, the method was testified in the copolymerization system of vinyl chloride/diallyl phathalate.
    VELOCITY FIELD SIMULATION OF GAS-LIQUID TWO-PHASE FLOW ON SIEVE TRAY
    YuanXigang, You Xueyi and Yu Guocong (K. T. Yu)(Chemical Engineering Research Center,Tianjin University,Tianjin 300072)
    1995, 46(4):  511-515. 
    Abstract ( 550 )   PDF (227KB) ( 134 )  
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    A two - fluid turbulence model is used to develop a two - dimensional theoretical model for predicting the two - phase flow on a sieve tray. Then the influence of the turbulence of the third dimension on the two - dimensional flow pattern is considered by correlating the constants of the model to the height of the overflow weir. Comparison of the computed results with the experiments of the sieve tray shows that the proposed model can successfully simulate the velocity field on the tray.