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Table of Content
25 June 1987, Volume 38 Issue 2
    化工学报
    Dynamic Simulation for a Multistage CountercurrentExtraction Process
    Dong Wenbao, Yan Hexin and Zhang Laosheng (Dalian Institute of Technology)
    1987, 38(2):  127-136. 
    Abstract ( 781 )   PDF (488KB) ( 265 )  
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    A varying coefficient, nonlinear dynamic cascade model has been derived in this paper, thus, in fact, is the extension of a simple linear dynamic cascade model, obtained through process mechanism studies on a Purex process occurring in a sixteen stage extractor with a countercurrent of first recycling. A variable step width floating-point linearization algorithm for solving the nonlinear dynamic cascade model is hereby proposed. Dynamic distribution of extracted materials in different stages and its variation with time disclosed. Comparison at experimental values with theoretical values in the sensitive stage, gives rather satisfactory conformity.
    Molecular Thermodynamics of Gas Solubility(Ⅱ) Henrys Constants of Gases in Polar Solvents
    Xu Yingnian, Hu Ying and Liu Guojie (Thermodynamics Research Laboratory, East China Institute of Chemical Technology)
    1987, 38(2):  137-145. 
    Abstract ( 763 )   PDF (499KB) ( 654 )  
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    The molecular thermodynamic model of gas solubility in non-polar solvents established by Hu, Xu and Prausnitz was extended to polar solvent systems. Henrys constants of various gases in water, alcohols, ketones, halo-genated aromatics and naphthalene substitutes are calculated. For all of 81 systems with 13 solvents whose maximum dipole moment is 2.83 Debye, satisfactory results are obtained with the use of only one adjustsble para-meter over a wide temperature range of 193.15-573.15K.
    Molecular Thermodynamics of Gas Solubility (Ⅲ) Henry s Constants of Gases in 1-1 Type Electrolytic solutions
    Xu Ying-nian and Hu Ying (Thermodynamics Research Laboratory, East China Institute of Chemical Technology)
    1987, 38(2):  146-155. 
    Abstract ( 658 )   PDF (570KB) ( 349 )  
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    The molecular thermodynamic model established by Hu, Xu and Prausnitz was extended to the gas solubility in electrolytic solutions. The influence of ion charge on the Helmholtz energy of fluid mixtures was taken into account by considering the interactions between the charge of ions located in the first coordination shell and the dipole or induced dipole of the central solute molecule. The contribution of the ions outside the first coordination shell can be neglected owing to the symmetrical distribution of the positive and negative ions with respect to the central solute molecule. The model in this paper includes a correlation equation for the effective hard sphere diameter of ions and the Paulings crystal diameter, σ = ησcrycysl, where η= - 6.645 + 747.2511/T + 2.95392 × 10-2T- 5.05798 × 10-5T2 + 3.2431 × 10-8 T3, for T>453.15K, η= 1.021. The results of calculations for 78 systems of gas solubilities in 1-1 type electrolytic solutions indicate that this model can predict the Henrys constants of gases in electrolytic solutions over a wide temperature range and a wide concentration range for electrolytes with the use of molecular parameters of gases in water only.
    Experimental Study of CVDA Design Curve
    Li Zezhen and Zeng Guangxing (General Machinery Research Institute, Ministry of Machine Building) Peng Ruying (Chemical Machinery Research Institute, Ministry of Chemical Industry)
    1987, 38(2):  156-164. 
    Abstract ( 661 )   PDF (393KB) ( 119 )  
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    It is found that the coefficients oi the COD design curve for BSI PD6493-1980 and JWES2805-1983 are within the 0.51.5) have to becomparatively greater than those in the low strain zone. Needless to say, such a great variation values at different sections of one and the same curve must be looked upon as being most irrational. Hence a CVDA ( Chinese Pressure Vessel Defect Assessment) design curve, to be employed in the Chinese CVDA code, is given in this paper:
    Simulation of Distillation Processes with Reactions in Series
    Xu Xien and Chen Hongfang (Department of Chemical Engineering, Tianjin University)
    1987, 38(2):  165-175. 
    Abstract ( 730 )   PDF (478KB) ( 185 )  
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    A mathematical model and a subsequent algorithm, simulating reactive distillation processes are presented in this paper. The model takes into accountreactions in series that occur within a distillation column and the algorithm is worked out with block tridiagonal matrix technique. Suggested existences of offtridiagonal submatrices and/or submatrices on the border render the solution of the block tridiagonal matrix equation better general ised. This would be a helpful tool in design computation. It would also be useful for observing the effect of variation in flow configurations between stages on intermediate product yield. The saponii ication of propylene chloro-hydrin is illustrated to verify the employment of the presented method. Satisfactory results are obtained.
    Application of "Vapor-phase Resistance Method"to the Study of Condensation inHorizontal Tubes
    Huang Hongding and Lu Wei (Chemical Engineering Department, Tianjin University)
    1987, 38(2):  176-184. 
    Abstract ( 588 )   PDF (433KB) ( 268 )  
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    A physical model as well as a mathematical model were established to describe and upgrade the "vapor-phase resistance method" suggested by Bell and Ghaly. Considering the effects of ripples at interfaces on vapor-phase resistance, a correction factor Vr was proposed. Another factor (θ/π)β which corrects the influence of the liquid pool along the bottom of the horizontal tube on the liquid-phase heat transfer coefficient was derived and therelationship of θ and β was correlated. A fully established method for calculating the convective condensation heat transfer coefficient was proposed. The heat transfer coefficients predicted by Bells method are approximately 10-15% lower than experimental values as the effect of ripples on vapor-phase resistance was not taken into account. Comparison of the predicted values of he from the modified vapor-phase resistance method with experimental data showed a deviation of ±10%.
    A New Approximate Analytical Method for the Calculation of the Effectiveness Factors on PorousPelletized Catalysts——The Equivalent ReactionTemperature Approximation
    Yuan Naiju and Ding Fuxin (Department of Chemical Engineering, Tsinghua University)
    1987, 38(2):  185-193. 
    Abstract ( 794 )   PDF (399KB) ( 173 )  
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    This paper presents an approximate analytical method far calculating the isothermal effectiveness factors (nth order reaction) and nonisothermal effectiveness factors (1st order reaction) in spherical and cylindrical porous catalyst pellets. By introducing an equivalent reaction temperature andwith rational assumption, certain analytical correlations can be obtained. Complications in calculations involved in heterogeneous catalytic reaction, can thus be rendered much simpler. These correlations can be readily used to predict the isothermal and nonisothermal catalyst effectiveness factors with good accuracy. It is pointed out that such a concept of equivalent reaction temperature with the proposed approximation method will be very useful in catalytic reactor design and catalyst analysis.
    Gas-Liquid Mass Transfer Characteristics in a Horizontal Vessel Equipped with Stirring Device(Ⅱ)
    Pan Qinmin Tang Furui, Gu Peiyrn, Shun Jianzhong and Pan Zuren (Department of Chemical Engineering, Zhejiang University)
    1987, 38(2):  194-202. 
    Abstract ( 597 )   PDF (355KB) ( 236 )  
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    Volumtric liquid-phase mass-transfer coefficients of oxygen-water and oxygen-C7 F15COONa aqueous solution systems were determined in a horizontal vessel equipped with a stirrar. Experiments were conducted through the steady physical absorption of oxygen in aqueons solutions. The effects ofvarious parameters, such as L/Dt, Di/Dt, Liquid hold-up, types and number of impellers etc, on the gas-liquid mass transfer coefficient kLa are being discussed. Correlations with experimental results were also given. In addition, a criterion for kLa to be used in the sealing-up of a horizontal vessel of similar geometry was given as: Fr=const. or Pv = const.
    Heat and Mass Transfer in a Rotary Drier
    Yuan Mian (Shanghai Research Institute of Chemical Industry)
    1987, 38(2):  203-211. 
    Abstract ( 619 )   PDF (454KB) ( 204 )  
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    This paper deals with a computing method for the design of the commercial rotary driers. The method has been proven in certain commercial rotary driers for the drying of different complex fertilizers. In the study of the heat transfer for particles, to be dried, a volume distribution frequency function of particle groups is introduced for the estimation of the interactions among particles during heat transfer. Parameters of this function are determined by employing a parameter estimation technique. Data collected in a pilot rotary drier serve for the estimation of the mentioned parameters. The suspension time of a particle in a rotary drier is defined to be equal to the drying time of the particle. To obtain the suspension time, mathematical methods, Monte Carlo method and Markov chain inclusive, are applied to simulate particle group transfer in the rotary drier.
    The Simulation Study of A Reactor-Three PhaseAzeotropic Distillation Tower System ( I ) Themodynamic Models and Calculations for AQuaternary System of Acetic Acid-Ethanol-Water-Ethyl Acetate
    Jing Wenkui and Yang Youqi (Computing Center, Ministry of Chemical Industry)
    1987, 38(2):  212-219. 
    Abstract ( 663 )   PDF (381KB) ( 203 )  
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    Specific thermodynamic models for a quaternary system of acetic acid-ethanol-water-ethyl acetate are established. The system is a strong polar mixture. With the exception of acetic acid azeotropic compounds exist in between the three other components. Furthermore, association of acetic acid in the vapor phase occurs in the system. All these features, tending to make calculations more camplex than ever, are taken into consideration. The ASOG combined model is chosen for calculating vapor-liquid equilibria, as well as for liquid-liquid equilibria and enthalpies.In calculating vapor-liquid and liquid-liquid equilibria, results from ASOG model are com pared with those from UNIFAC model. The thermodynamic models presented in this paper correlate very well with about 150 experimental data and are successfully used in the simulation of an industrial tower integrated with a reboiler as a reactor.
    The Simulation Study of A Reactor-Three Phase Azeotropic Distillation Tower System (Ⅱ) Simulation Calculations of the Reactor-Azeotropic DistillationTower System
    Wang Qingtian, Ling Weiming, Wang Xiugin and Yang Youqi (Computing Center, ministry of Chemical Industry)
    1987, 38(2):  220-229. 
    Abstract ( 661 )   PDF (441KB) ( 262 )  
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    The key facility for producing ethyl acetate is a complex distillation column with a reboiler performing as an esterification reactor. An algorithm, employing Block-Hegners algorithm together with a relaxation method has been taken for the simulation of this reactor-three phase distillation column system. More stable convergence has thus been obtained. Furthermore, by using the sparse matrix approach, less storage requirements are needed, allowing the problem to be solved in a microcomputer. Twelve case studies are conducted using this algorithm. Calculated results are compared with data measured in an operating plant.
    Analysis of the Filter-Consolidation Stage in a Filter Press
    Li Qingbin, Sun Chi, Wang Zhonglai and Wu Yanxiang (Department of Chemical Engineering, Fuzhou University)
    1987, 38(2):  230-239. 
    Abstract ( 631 )   PDF (447KB) ( 212 )  
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    Filtration proceeds in a filter press primarily in two stages-filtration and filter-consolidation. Filter-consolidation conforming to the so-called Terzaghis model in soil mechanics is the majar concern in the present piper. A partial defferential equation treating the filter-consolidation as a three-dimensional model, is given as; or where the filter-consolidation coerricient Cv can easily be determined by experimentation. It follows that the filter-consolidation equation is; It is demonstrated that the above eqouation can be applied to constant pressure filter-consolidation in a filter press. Results of high accuracies are claimed.
    Analysis of Reaction Rate of Coal Char Gasified with Steam
    Chin Ge, Yang Baotian, Qu Xueru and Liu Guifen (Shen Yang institute of Chemical Engineering)
    1987, 38(2):  240-248. 
    Abstract ( 624 )   PDF (418KB) ( 143 )  
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    Seven different samples of coal chars were gasified with steam in a fixed-bed differential reactor, operating under atmospheric pressure. A generalized kinetic equation for the gasification of coal char with steam was established. Such basic data obtained might be found useful in gasification furnace design work as well as in gasification technology. The initial gasification rate of coal char could be expressed as: (1) The relationship between char conversion x and the rate canstant was found to be: Changes in specific surface area of pores could be obtained from the random pore model introduced by Bhatia and Perimutter: (3) where was a characteristic physical parameter of coal Putting Eq. (3) into Eq. (1), the generalized rate expression becamedx/dt =KS0PH2o(1 - x) ( 4 ) Integrating Eq. (4) with x = 0 at t = 0, char conversion at any period ought be. x = 1 - exp[ - K S0PH2ot (1 + b/4K S0PH2ot) ( 5 ) Using Eq. (4) rate canstant K could be evaluted from the observed initial gasification rate(dx/dt)x=0 such as (6) Putting K thus obtained at any specific reaction temperature into Eq. (5), char conversion at any desired interval might be predicted. Calculated values correlated rather satisfactorily experimental results obtained. Further studies revealed that the production rate of carbon-borne gases related to the overall gasification rate of coal in the following manner: (7)
    Thermodynamics of Aqueous Sodium Chloride at High Temperature and Pressure (Ⅱ) Thermodynamic Properties of Aqueous NaCl to 823 K and 100 MPa
    Li Yigui Kenneth S. Pitzer (Department of Chemical Engineering,Qinghua Universiity) (Department of Chemistry University of Calilfornia Berkeley, U. S. A. )
    1987, 38(2):  249-255. 
    Abstract ( 624 )   PDF (313KB) ( 148 )  
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    Pitzer-Li equation is employed for the evaluation of the thermodyna-mic properties of aqueous NaCl up to 823 K and 100 MPa, with maximum concentration of NaCl up to 65.2 wt%, which happens to be the saturation solubility of NaCl at the triple point. Thermodynamic properties evaluated include water activity, mean ionic activity coefficient of NaCl and Gibbs free energy. The calculated values correlate quite well with experimental data obtained. Parameters of short-range interparticle interaction (w) and Gibbs energies of NaCl fusion (△sG20/RT) over 623-823 K and up to 100 MPa required for such calculations are also presented. The changes of w with changes in temperatures are discussed. A reference pressure method is introduced to calculate the values of d, ρ and Ax for the Debye-Huckel term in PL equation at all lower pressures over the 623-823 K range and the reference pressures P, at different temperatures are also given.