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Table of Content
25 August 1991, Volume 42 Issue 4
    化工学报
    Calculation of y from T, p and x Data in Vapor-Liquid Equilibrium Using Spline Function Method ( I ) Binary System
    Liu Honglai, Ying Xugen and Hu Ying (Thermodynamics Research Laboratory, East China Institute of Chemical Technology, Shanghai)
    1991, 42(4):  393-399. 
    Abstract ( 482 )   PDF (339KB) ( 126 )  
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    By using a cubic spline function to describe the binary excess free enthalpy function Q, a new indirect method for calculating binary vapor composition y from T, p and liquid composition x has been established. Broyden-Newton -Raphson iteration procedure was used for solving the differential equations. Practical calculation examples indicated that this method was reliable and showed good convergence. The calculated results were in good agreement with the experimental data. Moreover, neglect of the excess properties during calculation exerts very little influence on the results.
    Calculation of y from T, p and x Data in Vapor-Liquid Equilibrium Using Spline Function Method (Ⅱ) Ternary System
    Liu Honglai, Ying Xugen and Hu Ying (Thermodynamics Research Laboratory, East China Institute of Chemical Technology, Shanghai)
    1991, 42(4):  400-406. 
    Abstract ( 515 )   PDF (383KB) ( 96 )  
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    By using a spline function for curved surface used in simulating the bending of a plate to describe the ternary excess free enthalpy function Q, a new indirect method for calculating ternary vapor composition y from T, p and liquid composition x was established. Broyden-Nowton-Raphson iteration procedure was used for solving the nonlinear equations. The calculation of 30 ternary systems from nearly ideal to highly nonideal phase behavior showed that this new method was very stable and reliable. The calculated results were in good agreement with the experimental data. More-over, this method had a variety of distinguishing features such as good convergence, no special requirement for initial values and little influence caused by neglecting the excess properties during calculation.
    Prediction of The Phase Behavior of Gas Condensates
    Wang Peng and Guo Tianmin (Beijing Graduate School, University of Petroleum, Beijing)
    1991, 42(4):  407-415. 
    Abstract ( 547 )   PDF (385KB) ( 214 )  
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    The method for correlating the parameters of Peng-Robinson equation of state has been improved. As compared with the original Peng-Robinson equation and Soave-Redlich-Kwong equation of state, the modified Peng-Robinson model significantly improves the predictions of saturated vapor pressure and liquid density of heavy hydrocarbons(C7+), however, only minor improvement in saturated vapor density prediction if observed. For light components(C7-), theprediction of saturated vapor pressure and vapor density by the modified Peng-Robinson model is as good as Soave-Redlich-Kwong and Peng-Robinson equations of state. However, the description of the saturated liquid density is far superior. The modified Peng-Robenson model is used to predict the phase behavior fo gas condensates (dew point pressure, constant mass expansion and constant volume depletion processes), and better results are obtained.
    Simulation of Temperature and Velocity Field in Cylindrical Combustion Chamber of Crude Oil Heater
    Liu Zhenfa, Huang Zuqi, Yang Guangjiong and Qian Jialin (University of Petroleum, URIACCE-2,SINOPEC, Beijing)
    1991, 42(4):  416-422. 
    Abstract ( 445 )   PDF (350KB) ( 105 )  
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    A two-dimensional mathematical model was developed for predicting the temperature and velocity field in a cylindrical combustion chamber. The two-equation turbulent model and Monte-Carlo method were used to simulate the turbulence and radiative heat transfer. Three different turbulence combustion models were considered. The differential equations were solved by a SIMPLE algorithm. The distribution of fuel and oxygen concentration, velocity, temperature and heat flux in a crude oil heater were predicted. The comparison between the calculated and measured temperature distributions showed that the prediction was successful.
    Lumped Kinetic Model for Catalytic Steam Reforming of Naphtha
    Li Shaofen, Li Lin and Liao Hui (Department of Chemical Engineering, Tianjin University, Tianjin)
    1991, 42(4):  423-431. 
    Abstract ( 608 )   PDF (409KB) ( 164 )  
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    Most kinetic studies of catalytic steam reforming of individual hydrocarbons have shown that the reaction products are carbon monoxide, carbon -dioxide, methane and hydrogen only, and the conversion rate equation of different hydrocarbons can be expressed in the same form but the rate constants are different. In addition, the water gas shift reaction is assumed to be at equilibrium in the reaction processes. In order to simulate catalytic steam reforming of naphtha, a relative reaction rate constant a, which is the ratio of the rate constant of species i to that of the reference species, was proposed. The value of a is used to distinguish a species from the others. When many hydrocarbons have the same value of a, they may be lumped as a psudospecies. Two continuous distribution functions D (a) and yo(a) were defined for naphtha. D(a) is called as species distribution function and y0(a) is the composition distribution function of naphtha. In this paper gamma distribution function was applied to represent D(a) and yo(a). The parameters of these distribution functions were estimated by use of the experimental results. If the activation energies of the hydrocarbons are the same, both D(a) and yo(a) do not depend upon the reaction temperature. The lumped kinetic model suggested fits with the experimental results satisfactorily.
    Oscillating Fluidization and Its Application
    Ouyang Fan, He Haibao and Weng Dacong (Institute of Chemical Metallurgy, Academia Sinica, Beijing)
    1991, 42(4):  432-440. 
    Abstract ( 518 )   PDF (419KB) ( 220 )  
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    Some phenomena of the oscillating fluidization of light particles (ρp>ρf) were studied. By solving the equation of the motion of a single particle in a sinusoidally oscillating fluid, we obtained a model describing the particle motion and a correlation involving some critical parameters of a heavy particle (ρp>ρf) going up against the gravity or of a light particle (ρp<ρf) going down against the buoyancy. Those models were verified by experiments with light particles of five particle sizes and three particle density and by the data of Liang and Dengs experiment with heavy particles. Then, we proposed a mathematical model of solids bed being loosened sinusoidally oscillating fluid, which was examined with an oscillating fluidized-bed reactor. Lastly, a novel bioreactor, oscillating fluidized-bed of immobilized yeast cell beads, was developed for producing alcohol, and showed very good performance. The carbon dioxide adhered to the surface of the beads was separated easily from the surface and released from the reactor as very small bubbles.
    A New Local Composition Mixing Rule Model and VLE Correlation
    Xu Nanping, Wang Yanru and Shi Jun (Nanjing Institute of Chemical Technology, Nanjing)
    1991, 42(4):  441-448. 
    Abstract ( 516 )   PDF (335KB) ( 127 )  
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    A new predictive model for the coordination number was proposed on the basis of the theory of radial distribution function. It was tested extensively by the Monte Carlo computer simulation data of square-well fluids.This model could predict the properties of square-well fluids with reasonable accuracy and no more parameters were needed. A simple local composition mixing rule independent of density was established and combined with the modified Peng-Robinson equation of state to constract a new vapor liquid equilibrium calculation method. This new method was used to correlate the vapor liquid equilibrium data for nonideal mixtures at low pressure successfully.
    Effect of Vapor Entrainment on Distillation Tray Efficiency
    Zhang Dongping, Wu Xiangzhi and Fu Jufu (Department of Chemical Engineering, Beijing Institute of Chemical Technolgy, Beijing)
    1991, 42(4):  449-457. 
    Abstract ( 615 )   PDF (413KB) ( 169 )  
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    A distillation tray efficiency mode] including the effect of vapor entrain-ment was developed for the emulsion flow regime or froth flow regime operation under Lewis case 1, 2 and 3 conditions. The effect of vapor entrain-ment on tray efficiency was systematically investigated for the three cases. The calculated values by the model were in good agreement with FRI experimental data.
    Molecular Topology and Solubility Parameterof Paraffins
    Du Hua and Liu Guojie (Department of Chemistry, East China Institute of Chemical Technology, Shanghai)
    1991, 42(4):  458-465. 
    Abstract ( 563 )   PDF (400KB) ( 174 )  
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    The equation (1) established with a modified van der Waals model in a previous paper can also be used to calculate solubility parameters of isomeric alkanes. A method of determining characteristic constants of paraffins from topological indexes is developed. The solubility parameters of paraffins can be predicted over a wide temperature range from the triple point to the critical point. The predicted results show that the consistency between calculated values and experimental values is excellent.
    Kinetics Study on Absorption of Carbon Dioxide in Aqueous MDEA
    Wang Yiwei, Zhang Chengfang and Qin Shujun (East China University of Chemical Technology, Shanghai)
    1991, 42(4):  466-474. 
    Abstract ( 554 )   PDF (393KB) ( 243 )  
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    Absorption rate of carbon dioxide in aqueous solution of methyl-diethanol-amine(MDEA) was determined in a disc column with circulating liquid flow under atmospheric pressure, 30-70℃ and 1.75-4.28kmol/m3 of MDEA. The equilibrium data for the system C02-MDEA-H2O were determined by an agitated bubble reactor of self-suction type. All experimental data of absorption rate in this study can be described by an expression of pseudo-first-order rapid reversible reaction, that is in which the apparent activation energy is 33.13 kJ/mol. The effects of temperature, degree of conversion and concentration of aqueous MDEA on absorption rate of carbon dioxide are discussed.
    Kinetics Study on Catalytic Hydrogenation of Glucose to Sorbitol
    Zhang Yingmao, Li Zaizi, Zheng Huiguo and Zhuang Liqiu (Department of Chemical Engineering, South China University of Technology, Guangzhou)
    1991, 42(4):  475-480. 
    Abstract ( 616 )   PDF (306KB) ( 153 )  
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    Kinetics study on the hydrogenation of glucose to sorbitol on Raney nickel was undertaken at 110 K to 140 K and under pressure 2.0 MPa to 6.0 MPa. Based on the experimental result, a suitable reaction model was selected, i. e. the desorption of sorbitol with reaction between molecularly absorbed hydrogen and absorbed glucose on the catalyst surface could be the controlling step. The intrinsic kinetic equation could be written as:
    Adsorption Processes of Benzene, Toluene and m-xylol from Air by Activated Carbon
    Tu Weiping, Yang Zhouru, Chen Huanqin and Yuan Xiaochun (Department of Chemical Engineering, South China University of Technology, Guangzhou)
    1991, 42(4):  481-487. 
    Abstract ( 625 )   PDF (307KB) ( 301 )  
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    In this paper the isothermal adsorption processes of binary and ternary mixtures of benzene, toluene and m-xylol are investigated in a fixed bed of activated carbon of different column heights and under various flow velocities. The model established is solved by the orthogonal collocation method and the fourth order Runge-Kutta method. The results show that the orthogonal collocation method has the advantages of less handling before computation and shorter computing time. A good agreement between the computation results and the experimental results is obtained.
    Determination of Excess Enthalpies and Effectof Association on Excess Enthalpies of BinaryMixtures Containing Alkanols
    Li Fan, Gao Mingshu and Chen jinwen (Department of Chemical Engineering, Tianjin University, Tianjin)
    1991, 42(4):  488-494. 
    Abstract ( 586 )   PDF (384KB) ( 94 )  
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    The excess enthalpies of five binary systems, n-octane-n-octanol, n-hep-tanol, i-propanol and n-nonane-2-butanol, i-propanol, were determined at 297.95K and under atmospheric pressure with the Calvet microcalorimeter. With the corrected QCSM associatioaal solution model, the effect of hydrogen bond association on excess enthalpies of alkane-alkanol binary systems was investigated. The AGSM group contribution model was modified, and the modified parameters for AGSM model was proposed. The prediction of excess enthalpies with modified AGSM model for the systems containing shorter chain alkanols is better than with AGSM model.
    Investigation of New Two-phase Closed Thermosyphon
    Gu Junjie, Shan Yankun and Huang Hongding (Chemical Engineering Department, Tianjin University, Tianjin)
    1991, 42(4):  495-501. 
    Abstract ( 546 )   PDF (277KB) ( 114 )  
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    A new two-phase closed thermosyphon without countercurrent flow was designed by inserting inner tubes in both the boiling and condensation sections and a stream distributer in the adiabatic section. A visual study was carried out and the heat transfer performance of such a thermosyphon was investigated. A fluid flow model (physical as well as mathematical) was proposed and tested in the visual observation and heat transfer experiment. Theoretical analyses and experimental investigations showed that the new two-phase closed thermosyphon not only had a higher stability in operation and a higher critical heat flux, but also had better heat transfer perfomance. A condensation model with vapor and liquid flowing cocurrently in annulus based on the Spliman et als model was proposed and the mean deviation between the model and the experiments was 19.4%. The main points oi its design were discussed.
    Constancy of Slurry Concentration in Filtration
    Wang Zhonglai (Department of Chemical Engineering, Fuzhou University, Fuzhou)
    1991, 42(4):  502-507. 
    Abstract ( 533 )   PDF (306KB) ( 166 )  
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    The slurry concentration plays an important role in filtration. Four concepts of concentration are developed, the conventional concentration of slurry 5, which is the mass fraction of solids in slurry from the slurry-tank,, the average concentration during filtration Sav defined by Sav =Ws/(ρV + mavWs), the percentage variation of the average concentratin Eav defined by Eav=| (S-Sav)/S |×100%, and the instantaneous concentration of slurry in filtration St, which is the concentration at cake/slurry interface. On the basis of material balance, the equation of the instan taneous concentration of slurry in filtration is derived as follows: where ρs is the true density of cake solids, ρ the density of filtrate, A the filtration area, V the volume of filtrate, i the number of drainage surfaces, L the thickness of filter-chamber, and εi the porosity at cake/slurry interface which is determined by the Compression-Permeability Cell tes.tThe experiments to measure dV/d(L/i) in the equation were made by use of the experimental apparatus for hydraulic pressure distributions.
    Calculation of Critical Loci of Mixtures by MH Equation of State with DDLC Mixing Rule
    Hu Wangming, Guo Xiping and Hou Yujun (Department of Chemical Engineering, Zhejiang University, Hangzhou)
    1991, 42(4):  508-513. 
    Abstract ( 571 )   PDF (282KB) ( 114 )  
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    The DDLC mixing rule has been developed for MH equation of state on the basis of two-fluid theory and the local mole fraction expression of a generalized NRTL model. It can be used to correlate the properties of most fluids under high pressure. The critical loci of 7 binary hydrocarbon mixtures and 17 typical binary systems, including polar-polar and nonpolar-polar system, are calculated by using the new mixing rule and the criteria for the critical point of a mixture suggested by Heidemann and Khalil. The accuracy is better than or comparable to commonly used cubic equation of state, and the improvement of evaluating Vc is most remarkable.
    Optical Fiber Method for Detecting Local Holdup of Three Phase Reactor
    Yu Qiang, Sun Jianzhong and Tang Furui (Department of Chemical Engineering, Zhejiang University, Hangzhou)
    1991, 42(4):  514-517. 
    Abstract ( 576 )   PDF (209KB) ( 190 )  
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    A set oi apparatus was established and used to measure the local holdup of each phase of gas-liquid-solid system simultaneously. According to the equation ε=K∑Δti/T, the signal peak and peak width time can be distinguished under the applied program. The experiment is stable and reliable. The errors among repeated experiments in average holdup measurements are less than 9%.It provides a fully-new reliable method for the detection of three phase reactor.