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Table of Content
25 August 1992, Volume 43 Issue 4
    化工学报
    ONE-DIMENSIONAL HYDRODYNAMIC MODEL FOR LIQUID HOLD-UP AND FLOW PATTERN TRANSITION IN TRICKLE-BED REACTORS
    Wang Rong, Mao Zaisha and Chen Jiayong (Institute of Chemical Metallurgy, Academic Sinica, Beijing 100080)
    1992, 43(4):  385-394. 
    Abstract ( 685 )   PDF (461KB) ( 127 )  
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    In this paper, the gas-liquid flow in interstices formed bysimple cubic lattice packing of spherical particles in a trickle-bed reactor is analyzed on the scale of particle size. Starting from the basic hydrodynamic equations of motion, a microscopic one-dimensional model is established. Numerical solution of the model leads to the liquid distribution over the particle and the total liquid hold-up in the trickling flow regime. By analysing the stability of liquid film on the particle surface, a criterion is proposed to predict the transition from trickling to pulsing flow. Comparison of the model prediction with available experimental data suggests the usefulness and generality of the hydrodynamic model proposed for trickle-bed reactors.
    REACTION MODEL ON THE PRODUCTION OF SINGLE CELL PROTEIN FROM CELLULOSE
    Zhou Yi, Yang Shouzhi, Xue Maojie, Zhia Jinrong and Li Zuohu (Institute of Chemical Metallurgy, Academia Sinica, Beijing 100080)
    1992, 43(4):  395-400. 
    Abstract ( 649 )   PDF (285KB) ( 146 )  
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    For the preparation of single cell protein from cellulose with Strep-tomyces No. 107, a simplified reaction model has been established based on the mathematical model developed by Armiger-Humphrey. The model consisted of 4 ordinary differential equations including 9 parameters to be estimated. Using the VAX-11/780 computer and a STYR/OPT optimization program developed in this Institute the parameters included in the model were estimated by optimization and the experimental results were simulated by the model satisfactorily. The value of the 9 parameters optimized were reasonable and the simulation of experimental results was successful.
    EVALUATION OF COAL CHAR GASIFICATION RATE BY THE NUMBER OF ACTIVE SITES
    Zhu Zibin and Zhang Chengfang (Department of Chemical Engineering, East China Institute of Chemical Technology, Shanghai 200237)Furusawa Takehiko and Adschiri Tadafumi (Department of Chemical Engineering, The University of Tokyo, Tokyo)
    1992, 43(4):  401-408. 
    Abstract ( 559 )   PDF (380KB) ( 171 )  
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    The number of active sites for nine kinds of coal char at high temperature were measured in CO2 gasification condition. Experimental results showed that the relationship of "volcano" shape between gasification rates and x and several ten times difference of gasification rates among a variety of coal char could be explained by the difference of number of active sites of coal char. The study results of nine kinds of coal char indicated that gasification rate per active site followed the equation:
    CALCULATION OF c_p-c_v FOR LIQUID AND LIQUID MIXTURES
    Liu Guojie, Shi Jibin and Bao Weiqun (East China Institute of Chemical Technology, Shanghai 200237)
    1992, 43(4):  409-416. 
    Abstract ( 790 )   PDF (369KB) ( 132 )  
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    A relation which can be used to calculate the difference between the heat capacity cp and cv for liquids at various temperatures has been established where R, T, V and α are gas constant, thermodynamic temperature, molar volume and thermal expansion coefficient respectively. A and B are two characteristic constants which can be obtained by the methods of group contribution and molecular topologic indexes. The calculated results agreed with experimental values satisfactorilly. The relation is also applicable to liquid mixtures, if simple mixing rule of A and B applies.
    CALCULATION OF VOLUMETRIC SPECIFIC HEAT CAPACITY AND ISOBARIC SPECIFIC HEAT CAPACITY OF REAL GASES USING PERTURBATION THEORY
    Song Xiaoming Zhao Guanchun (Xian Jiaotong University, Xian 710049)
    1992, 43(4):  417-423. 
    Abstract ( 827 )   PDF (325KB) ( 262 )  
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    The volumetric specific heat capacity and isobaric heat capacity of real gases were calculated using perturbation theory in statistical thermodynamics and the accuracy was improved by using an improved method inthis paper. The calculation of numerous points of the saturated and superheated vapor of real fluids such as N2, O2,SO2,CO,CO2,CH4,C2H2, C2H4, C2H6, C3H8, etc., showed that the results were in good agreement with the values reported in literature and improved accuracy was achieved in comparison with the general L-K equation of state and the equation of specific heat capacity in literature. The specific heat capacity at constant volume and the specific heat capacity at constant pressure of real gases at a given state can then be calculated only when the critical parameters Tc, Vc and acentric factor are known. Although this method is not fit for direct calculation for its complexity, it is efficient, simple and practical in computerized calculation.
    PHASE EQUILIBRIUM FOR FIVE-COMPONENT SYSTEM OF NaOH-Na_2CO_3-Na_2SO_4-NaCl-H_2O AT 150℃
    Liu Jinrong, Zhang Chending, Li Guanshe, Zhang Tong and Wang Hongwang (Natural Soda and Inorganic Salts Research Laboratory, Inner Mongolian Institute of Technology, Hohhot 010062)
    1992, 43(4):  424-431. 
    Abstract ( 808 )   PDF (360KB) ( 248 )  
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    In this work, the apparatus for phase equilibrium data determi-nation has been developed of water-salt system at high temperature. A five-component system NaOH-Na2CO3-Na2SO4-NaCl-H2O was studied at 150℃. The work completed the phase equilibrium investigation for the system at 150℃. On the basis of the phase equilibrium data obtained present and those available in literature, the phase diagrams were plotted for the NaOH-Na2CO3-Na2SO4-NaCl-H2O five component system at 150℃. According to the phase diagrams, the author made phase diagram calculation for the evaporation process in manufacturing caustic soda from natural soda in Inner Mongolia by caustic method.
    SYSTEM OUTPUT DISTRIBUTION BASED MODELLING AND CONTROL
    Hu Zexin and Jiang Weisun (East China Institute of Chemical Technology, Shanghai 200237)
    1992, 43(4):  432-440. 
    Abstract ( 522 )   PDF (432KB) ( 133 )  
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    The method of modelling and control based on characteristic variables chosen according to system output distributions is presented. Simulation results are satisfactory. Experiments are carried out in a pilot binary distillation column (15 trays with feed of alcohol and water mixture) controlled by a microcomputer system. It is shown that the simlified model can approximate the complete model of distillation column very well and the control strategy has significant advantage compared with a conventional control strategy. This method can also be applied to a kind of high order, nonlinear, distributed parameter systems, which is difficult to deal with.
    COKING MECHANISM AND MODEL OF TRANSFER LINE EXCHANGER FOR QUENCHING PYROLYSIS REACTION OF GAS OIL
    Zou Renjun, Lou Qiangkun and Zhu Tingzhe (Hebei Institute of Technology, Tianjin 300130)
    1992, 43(4):  441-446. 
    Abstract ( 682 )   PDF (317KB) ( 229 )  
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    A set of micro-system for investigating coking process in transfer line exchanger (TLE) for quenching pyrolysis reaction of gas oil was designed and assembled by the authors. It was clear from the experiment that the coking mechanism in TLE was mass transfer and condensation-surface poly-condensation reaction. The authors first showed a characteristic transition temperature of coking process in TLE. The mass transfer and condensation process could be the controlling step of coking process when the surface temperature was higher than the transition point, otherwise, surface-polycondensa-tion reaction could be the controlling step. On the basis of the above-mentioned mechanism, the authors proposed a coking model of TLE and simulated the industrial TLE. The agreement between the simulation results and observed industrial data was good.
    NUMERICAL ANALYSIS OF CHEMICAL VAPOR DEPOSITION REACTORS ( I ) ANALYSIS OF CVD OF TiN COATING IN A COLD-WALL REACTOR
    Ding Ping and Yuan Weikang (East China Institute of Chemical Technology, Shanghai 200237)
    1992, 43(4):  447-454. 
    Abstract ( 555 )   PDF (389KB) ( 120 )  
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    The fluid flow, heat transfer and mass transfer are incorporated in a two-dimensional model of an axisymmetric reactor. The problem is solved numerically by Galerkin finite element method, using a velocity-pressure formulation for the N-S equations. The dependence of density, viscosity, thermal conductivity and diffusion coefficient on temperature are considered and the presence of free convection is simulated rather well. The distributions of velocity, temperature, TiCl4 concentration in the reactor and the deposition rate of TiN on the substrate are predicted. The computational results are in good agreement with experimental data.
    NUMERICAL ANALYSIS OF CHEMICAL VAPOR DEPOSITION REACTORS (Ⅱ) ANALYSIS OF FLUID FLOW, HEAT AND MASS TRANSFER IN TWO-TYPE OF REACTORS
    Ding Ping and Yuan Weikang (East China Institute of Chemical Technology, Shanghai 200237)
    1992, 43(4):  455-460. 
    Abstract ( 655 )   PDF (301KB) ( 138 )  
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    According to computational results by Calerkin finite element method, comparisons are presented in terms of the distributions of velocity, temperature, TiCl4 concentration and the deposition rate of TiN in hot-wall reactors and cold-wall reactors. The effects of flow patterns, heat and mass transfer on coating qualities and deposition rate of TiN are analysed. The general results provide the guidelines for kinetic studies and the design of commercial CVD reactors.
    AN EXPERIMENTAL RESEARCH ON THE SHELL-SIDE VELOCITY AND TEMPERATURE FIELDS IN A SHELL-TUBE WASTE HEAT BOILER
    Guo Liejin, Zhang Mingyuan and Chen Xuejun (Xi an Jiaotong University, Xian 710049)Wang Puxun and Zhu Lin (Chemical Machinery Research Institute, Lanzhou 730060)
    1992, 43(4):  461-468. 
    Abstract ( 487 )   PDF (338KB) ( 127 )  
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    The velocity and temperature profiles of water flow in the shell-side of a shell-tube waste heat boiler were experimentally studied. The influences of some factors on the flow and heat transfer characteristics were investigated. Some further analyses and discussion on the flow field were made, and some operating problems were explained. The test system and measuring method are described in detail.
    ESTIMATION OF MIXING TIME FOR HELICAL SCREW IMPELLERS WITH A DRAUGHT TUBE
    Zhu Xiulin (Chemical Engineering Department, Suzhou University, Suzhou 215006)Song Qiuan, Wang Kai and Pan Zuren (Chemical Engineering Department, Zhejiang University, Hangshou 310027)
    1992, 43(4):  469-474. 
    Abstract ( 619 )   PDF (274KB) ( 210 )  
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    The distributions of circulation time were obtained by means of a single suspend bead for sixteen types of helical screw impellers with a draught tube in the laminar regime. The distributions were almost independent of the Reynolds number and were characterized by a single peak.
    EXPERIMENTAL STUDY ON HEAT TRANSFER BETWEEN SUSPENSIONS AND IMMERSED VERTICAL SURFACE IN FAST FLUIDIZED BED
    Bai Dingrong, Jin Yong, Yu Zhiqing and Cao Chunshe (Department of Chemical Engineering, Tsinghua University, Beijing 100084)
    1992, 43(4):  475-481. 
    Abstract ( 664 )   PDF (403KB) ( 127 )  
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    The profiles of local heat transfer coefficient along the axial direction of a probe were measured in a 8m tall, 186mm ID cold model fast flu-idized bed at different radial positions. All data were obtained by using a specially designed heat probe assembly. In the experiments elimination of axial thermal conduction and constant bulk density along the probe were ensured. The experiments show that regardless of the radial position where the probe is located, the local heat transfer coefficients decrease gradually from top to bottom of the probe. It means that the particles always aggregate at the probe surface, forming a layer and moving downwards along the probe surface if the probe is large enough. In light of this mechanism, the experiments have confirmed that the local heat transfer coefficients are mainly dependent on the local bulk density around the probe and the particle renewal frequency at the surface, which in turn vary with gas velocity. The contribution of gas convection can be neglected in comparison with that of the transient heat transfer between particles and the probe surface.
    AN IMPROVED DYNAMIC MODEL OF MULTICOMPONENT DISTILLATION COLUMN
    Huang Kejin, Qian Jixin, Sun Youxian and Chou Chunhui (Institute of Industrial Process Control, Zhejiang University, Hangzhou 310027)
    1992, 43(4):  482-488. 
    Abstract ( 934 )   PDF (329KB) ( 171 )  
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    An improved dynamic model of nonideal multicomponent distillation column is presented in this paper, in which the simultaneous effects of mass and heat transfer, tray hydraulics, tray efficiency and reboiler dynamics are taken into account. It overcomes the shortcomings of the model derived in a previous paper[1], by adding vapor-liquid equilibrium bubble-point calculation. Therefore, higher accuracy and greater usefulness of the model have been achieved. It can be used to simulate the distillation column which separates either an ideal system or a highly nonideal system. The Gears procedure is adopted as a simulation method for its stable property. It is very effective for solving the differential equations with high stiffness ratio. An acrylonitrile extractive distillation column is taken as an example to verify the model given here. The model can really represent the actual dynamics of the distillation column.
    CALCULATION OF CRITICAL POINTS FOR LINEAR POLYETHYLENE-PROPANE SYSTEM UNDER SUPERCRITICAL CONDITIONS
    Tan Liyang (Department of Environmental Chemistry, Polytechnic University of Beijing, Beijing 100022)
    1992, 43(4):  489-495. 
    Abstract ( 551 )   PDF (300KB) ( 111 )  
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    In terms of the Flory-Huggins polymer solution theory as extended by Koningsveld and Kleintjens, an algorithm for calculating critical points based on experimental cloud point curves has been developed for the polyethylene-pfopane system. Results suggest that the method developed in this work can be easily used and the calculated critical points agree fairly well with the experimental data in the concentration range less than 10% (weight). In engineering design the method can be used to estimate critical points and cloud point curves in supercritical fluid fractionation of polymers (polyethylene-propane) .
    VELOCITY FIELD MEASUREMENT OF PARTICLE SWARM IN A SETTLER BY PARTICLE IMAGEVELOCIMETRY
    Li Xingang, Du Yingsheng and Yu Guocong (K.T.YU) (Chemical Engineering Research Center, Tianjin University, Tianjin 300072)Zhou Ge (Department of Precision Instrument Engineering, Tianjin University)
    1992, 43(4):  496-500. 
    Abstract ( 640 )   PDF (316KB) ( 131 )  
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    The statistical mean velocities of particle swarm in several regions of a settler were measured by using a method in such a way that the multi-exposure images were taken by Particle Image Velocimetry, then the films obtained were analyzed by optical Fourier transform to produce Younges fringe. The success of this experimental method was demonstrated by obtaining the velocity field of particle swarm in a settler, which may contribute significantly to the further understanding of the settling process.
    MEASUREMENT OF GAS CONCENTRATION DISTRIBUTION IN ADSORPTION BED
    Zhou Ming, Wang Zhixiang, Wang Lu and Yu Guocong(K. T. Yu) (Chemical Engineering Research Center, Tianjin University, Tianjin 300072)
    1992, 43(4):  501-505. 
    Abstract ( 549 )   PDF (226KB) ( 274 )  
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    A gas concentration detecting device consisting of catalytic burning sensors for gas concentration detection and an accompanying on-line microcomputer data collecting system was set-up to investigate axial and radial mixing characteristics of gas in adsorption bed. It could measure and record combustible gas concentration at sixteen different positions simultaneously in adsorption bed. Experiments were carried out with methane-air-5A molecular sieve in a267 mm diameter adsorption column at different gas flow rates. Methane used as adsorbate was continuously fed into the center of bed entrance section and its concentration distributions were obtained at three different levels of the column. This device can also be used to measure temperature distribution if temperature sensors are used instead of that for gas concentration measurement.
    GRAFT MODIFICATION OF THERMOPLASTIC ELASTOMER SBS
    Zhang Quan, Shi yongxi, Wang Hongpeng, Li Yang and Li Yu (Beijing Institute of Chemical Technology, Beijing 100029)
    1992, 43(4):  506-509. 
    Abstract ( 841 )   PDF (315KB) ( 260 )  
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    Due to its chemical composition and structure SBS has unique adhesive function. However, in the absence of polar group in SBS macromolecules, its adhesion to metal is weak. In this paper, SBS was melted and reacted with maleic anhydride (MAH), methyl methacrylate (MMA) and the mixture of MAH and MMA to improve its adhesion to metal, The results show that the strength of adhesion to alumimium of SBS adhesives modified by melting reaction with the mixture of MAH and MMA is stronger than those of SBS modified by MAH or MMA separately. Besides, the melting reaction had an notable effect on the formation of microphase segregation structure of SBS.
    MODIFIED APPROXIMATE SOLUTION FOR GRAETZ AND LEVEQUE PROBLEMS FROM ADVANCINGFRONT THEORY
    Zhang Guoliang and Wang Shaoting (Institute of Biomedical Engineering, Tianjin University, Tianjin 300072)
    1992, 43(4):  510-514. 
    Abstract ( 736 )   PDF (209KB) ( 135 )  
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    The advancing front theory is an approximate solution for mass transfer of O2 within blood when the reaction of O2 with homoglobin can be assumed to be very fast. An approximate solution for the Graetz and Leveque problems from the advancing front theory is modified according to the analogy between momentum and mass transfer in this study. By substituting third order polynomial for linear relationship of O2 concentration profile in the saturated region, the deviation of the modified approximate solution from that of exact solution is decreased to 4.36% from Stroeves 15.1%.