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Table of Content
25 June 1986, Volume 37 Issue 2
    化工学报
    Investigation on Methine Type Disperse Dyes ofBenzthiophenone Derivatives (I) Absorption-Spectrum-Structure Relationship
    Hou Yufen and Li Zhoushu (Chemical Engineering Department, Dalian Institute of Technology)
    1986, 37(2):  129-139. 
    Abstract ( 527 )   PDF (502KB) ( 131 )  
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    The general formula of methine disperse dyes of benzthiophen-one derivatives is where R1 and R2 may be the same or different non-ionic hydrophobic groups such as H, Me, CH2CN, CH2OH, CH2Cl, C6H5, (CH2)4CH3 etc, X represents H, Me etc; and Z represents O or C(Y)Y, where Y and Y may be the same or different polar groups such as CN, COOC2H5 etc. The absorption spectra of dyes are different for different substituents X, Z, R1 and R2. The polarities of R1 and R2 are represented by η, which are related to the pKa values corresponding to the substituents R1 and R2. The empiric equations of the relationship of the absorption spectra of dyes with η were obtained in acetone. The effect of substituent X, Z on absorption spectrum were studied. Otherwise the relation of the absorption spectrum of dyes with η are similar in other four different solvents.
    Parameters in Models of Excess Gibbs Free Energy by the Chromatographic Slope Method
    Shen Shubao, Wang Shaokun, Zhang Juzen and Shi Jun (Nanjing Institute of Chemical Technology)
    1986, 37(2):  140-150. 
    Abstract ( 603 )   PDF (593KB) ( 252 )  
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    Two equations of (r/x)x=0-a modified Kikic-Renon equation and a Valentin-Guiochon equation-have been studied. Values of r1∞ and (dlnr1/dx1)x1=1 by these two equations for 29 binary systems, have been calculated from GLC data, the parameters in some models of excess Gibbs free energy evaluated, and the vapor-liquid equilibrium date predicted. The results are satisfactory. Vlentin-Guiochon equation was simplified leading to a simpler (r/ x)x=0 expression. Then values of r1∞ and (dlnr1/dx1)x=0 by the simplified Valentin-Guiochon equation for 56 binary systems containing alcohols or water were taken from Gmehlings VLE data collection, and the same predicting procedures repeated. These procedures have also been applied to 43 binary systems containing various polar and nonpolar, volatile and nonvolatile component, in which the values of r1∞ and) dlnr1/dx1)x1=0 were calculated by the simplified Valentin-Guiochen equation from GLC data. The predicted VLE data are all consistent with those in the literature. Limits of application of the three equations and methods to transform the two-parameter model of excess Gibbs free energy into one-parameter model, were then discussed.
    Residence Time Profile and Plate Efficiency for a Large Tray with Single-Pass or Two-Pass Liquid Flow
    Yu Guocong(K. T. Yu), Huang Jie and Zhang Zuoting (Chemical Engineering Research Center, Tianjin University)
    1986, 37(2):  151-161. 
    Abstract ( 802 )   PDF (499KB) ( 335 )  
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    This paper presents the residence time profiles for single-pass and two-pass liquid flows by tracer technique for a water/air system in an experimental semicircular sieve tray of 2 meters in diameter. Analysis of residence time profiles indicates complicated flow pattern for single-pass flow. For two-pass liquid, similar flow pattern is observed from the residence profiles on center downcomer tray, while relatively uniform convergent flow is found on side downcomer tray. A mathematical model based on residence time profiles for single-pass tray is presented to compute the concentration profiles and the enhancement ratio, i. e. the ratio of the Murphree tray efficiency to the point efficiency. The average deviation between the predicted and the experimental tray efficiency found in literature is less in present model than the other existing models. Similar modeling for two-pass liquid flow is also presented including central downcomer and side downcomer tray, the proposed model agrees closely with recently published results. Finally, this paper introduces two kinds of new constructions on the experimental tray, which have shown successful improvement on the uniformity of liquid flow. These constructions are simple, practical and capable of increasing tray efficiency considerably.
    Exergy Analysis of Distillation Stages by Non-Equilibrium Thermodynamics
    Sun Zhifa, He Yaowen and Jiang Chusheng (Beijing Institute of Chemical Technology)
    1986, 37(2):  162-171. 
    Abstract ( 601 )   PDF (428KB) ( 152 )  
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    An exergy balance equation which relates to heat and mass transfer on distillation stages was derived from the theory of non - equilibrium thermodynamics. This equation was used to analyze an ethylene distillation tower, and the result checked satisfactorily with that of the equilibrium thermodynamic exergy analysis. In a multiphase discontinuous system, each phase may be considered as a subsystem and all subsystems are separated by interfaces. With appropriate hypotheses, the equation of exergy loss relating to energy and mass transfer through interfaces may be expressed as follows: Thus, profound insight into distillation process could be gained to provide ideas for further improvement of the distillation scheme.
    Study on Ebulliometry and a Leaning Ebulliometer
    Cai Zhiliang, Zhou Xingfeng and Hong Ruicha (Chemical Engineering Department, Zhejiang Institute of Technology)
    1986, 37(2):  172-182. 
    Abstract ( 550 )   PDF (550KB) ( 241 )  
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    It is shown that when ab ebulliometer operates steadily, the relation between the gravimetric concentration X10, and the concentration of the equilibrium liquid phase x1, is where K1 = y1/x1 is the phase equilibrium constant; r = ng/nl, the ratio of the vapor condensate reflux to the liquid one; a=(Ng-rNl)/N,Ng and Nl are the holdups of the vapor and the liquid respectively, and N is the total amount of the solution inside the ebulliometer. On this base, a rigorous formula for the infinite dilution activity coefficient γ∞ was derived: where H0=(r0 + a0)/(1+r0), the subscript "0" denoting x10 =0; The symbols in above expression was defined by C. A. Eckert, et al. A leaning ebulliometer was made as a modified Swietoslawski version with the Cottrell pump inserted in the insulating jacket. At an angle of 30°- 45° to the horizantal it operated steadily under the condition of r = 0 and a <0.005, so that | (x10-x1)/x1|+<0.5|K1 -1| %. The leaning ebulliometer is a very useful tool for measuring VLE (T-P-x) and γ∞.
    Prediction of Breakthrough Curves for Fixed Beds
    Wang Changtai and Lin Cheng (Department of Chemical Engineering, Fuzhou University)
    1986, 37(2):  183-192. 
    Abstract ( 556 )   PDF (469KB) ( 170 )  
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    A simple, easy-to-use approximate equation, in the form of a normal probability distribution function, was derived for breakthrough curves of fixed-bed reactors or adsorbers. The equation predicts breakthrough curves and evolution of concentration or temperature distribution in fixed beds, with an accuracy higher than, or comparable to, other equations previously proposed.
    The Synthesis of Energy Integrated Distillation Trains
    (Chemical Engineering Research Center, Tianjin University) Zhou Li, He Zhimin and Yu Guocong(K. T. Yu)
    1986, 37(2):  193-203. 
    Abstract ( 547 )   PDF (518KB) ( 248 )  
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    The energy integrated distillation train is synthesized in two levels: Maximizing the net benefits of heat inte-gration over both design variables of the simple columns and heat-matches among them, and then minimizing the total costs of the train over all separation sequences by means of integration trees. It does not involve much computation because the feasible heat matches are few and a simplified technique to determine the optimal distillation pressure is employed. The synthesis procedure is illustrated by a popular example, and the comparison of the synthesis results of different methods shows that the new strategy can achieve more savings in both energy and separation costs.
    Heat Transfer and Pressure Drop Calculation for Cylindrical Pipe Furnaces Processing Crude Oil
    Huang Zuqi, Yang Guangjiong and Qian Jialin (East China Petroleum Institute)
    1986, 37(2):  204-211. 
    Abstract ( 717 )   PDF (408KB) ( 177 )  
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    Heat transfer in the radiation chamber of a cylindrical tubular heater is analyzed. An energy-conservation model using cylindrical coordinates in the form of integral and differential equations is used for describing the radiative and convective heat transfer in a combustion chamber. The Monte Carlo method and the difference method are used for solving the energy equation. For calculation inside the tubes, crude oil is treated as a mixture of many pseudo-pure components, and the Soave equation is used for the calculation of vapor-liquid equilibrium and the physical and thermo-dynamical properties of the liquid and vapor phases. Heat transfer and pressure drop of the fluid flow inside the pipe are next estimated. Results calculated by using a PDP-11/45 computer are compared with the operating data of the crude heater in a refinery. It is believed that model developed and the calculation program are acceptable.
    Heat Transfer to Horizontal Tube in Freeboard Region of Fluidized Bed
    Shi Mingheng (Nanjing Institute of Technology)
    1986, 37(2):  212-219. 
    Abstract ( 508 )   PDF (421KB) ( 96 )  
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    Heat transfer to a horizontal tube in the freeboard region of a flu-idized bed has been investigated. The freeboard region can be divided into three different zones for which different heat transfer correlations should be used. By introducing the dimensionless height number X, the heat transfer coefficients can be calculated by use of the correlations in bed for the first zone (X<0.1-0.14), and for the second zone, which is the main part of the freeboard, equation (5) can be used. The heat transfer coefficients in the third zone (X≥1) are actually equal to that calculated by MacAdams correlation for the cross flow of air. Certain major factors which affect heat transfer in the freeboard region were also examined.
    Effect of Vapor Mixing on Tray Efficiency
    Lu Xiulin, Zhao Daqi and, Zhang Pingan (Department of Chemical Engineering, East China Institute of Chemical Technology)
    1986, 37(2):  220-227. 
    Abstract ( 385 )   PDF (352KB) ( 82 )  
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    A new mixing model is presented for taking into account the effect of vapor mixing on tray efficiency under the condition of Partial mixing of liquid, arid mathematical correlations are obtained to predict the tray efficiency of distillation column. The calculated results are in good agreement with that reported by Ashley and Haselden and by Hirotake Katayama et al. The mathematical correlations proposed in this paper are simpler and more convenient to use. For limiting cases, the present mathematical model can be simplified to equations identical with those published in the literature.
    Simplified Calculation of Heat Transfer forTangential Flow of Polymer Melt in aCylindical Annular Space
    Jin Deqian (Beijing Institute of Chemical Technology)
    1986, 37(2):  228-237. 
    Abstract ( 505 )   PDF (415KB) ( 99 )  
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    For simplified calculation of heat transfer with viscous heat generation, the tangential flow of polymer melt in a cylindical annular space was transformed into drag-flow between two parallel plates by using the finite difference method. The longitudinal Temperature distribution and the temperature gradients at the surfaces of the plates was derived. The local Nu-sselt Number and the local heat transfer coefficient at the plate surfaces can thus be calculated. The calculated results show that the average melt temperature Ts rises gradually along the cylinder length, and the rate of temperature rise diminished slowly until it approaches zero. Typically a length of 27.72 meters is required for obtaining a fully developed temperature profile. Approximate methods for heat transfer calculation are suggested for viscous heat generation in polymer processing installations such as screw extruder, shear head, run-of-the-mold cavity, etc.
    Perturbed-Hard-Chain Equation of State for Vapor-Liquid Equilibria for Systems Containing Polar Solvents
    Pan Shaqing and Ma Dexian (Beijing Institute of Chemical Technology)
    1986, 37(2):  238-247. 
    Abstract ( 439 )   PDF (426KB) ( 207 )  
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    The present paper explores the applicability of the perturbed-hard-chain equation of state for estimating vapor-liquid equilibria for solutions of CO2, CO, CH4, H2, N2 and Ar in polar solvents such as H2O and CH3OH. Related parameters thus calculated, from literature data, indicated that for mixtures consisting of polar compounds alone or of polar and nonpolar compounds, the adjustable parameters are all temperature-related, and should be computed from the polynomial equation: A computer program was formulated for the eight-component system, CH3OH-H2O-CO2-CO-H2-CH4-N2-Ar. The resulting simulation for the vapor-liquid separation in methanol production checked closely the flowsheet data of Lurgi, Speichim and Billingham.
    Determination and Prediction of Surface Tension for Two Quaternary Liquid Mixtures
    Wang Zigao and Fu Jufu (Beijing Institute of Chemical Technology)
    1986, 37(2):  248-251. 
    Abstract ( 475 )   PDF (234KB) ( 132 )  
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    Surface tensions of two typical quaternary liquid mixtures, one aqueous and the other non-aqueous, were measured at 25℃. The aqueous system studied was acetic acid-acetone-ethanol-water and the non-aqueous, acetic acid-benzene-ethanol-ethyl-acetate. Experimental data agreed well with results predicted by the equation previously proposed by the authors.
    A Kinetic Study of Carbon Monoxide Methanation in a Gradientless Reactor with Internal Recycle
    Zhang Jiyan H. Hofmann (Department of Chemical Engineering,Tianjin University) (Institut fur Technische Chemie I der Universitut Erlangen-Nurnberg)
    1986, 37(2):  252-257. 
    Abstract ( 501 )   PDF (311KB) ( 171 )  
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    A kinetic study of CO-methanation has been carried out in a gradi-entless reactor with two commercial catalysts R and G, which have different pore structures but similar compositions, in the temperature range of from 190 to 270℃, under a total pressure of 16 bar, with mole ratio N2/H2 = 110.33 - 3, volumetric flow rate of 80 - 120 Nl/h, and CO-concentration in the reactor xco, e=3%. Experimental results can be formulated by a Langmuir-Hinshelwood type model as follows: By comparision, it was found that these two catalysts had obviously different activities, attributable to their different pore structures and diffusion properties. During experimentation, concentration oscillations of the reacting species were observed.