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Table of Content
25 March 1984, Volume 35 Issue 1
    化工学报
    A New Plate-to-plate Method for Calculating Azeotropic Distillation Processes (Ⅲ) Performance predicion of azeotropic distillation processes
    Shan Wenwei and Chen Mingheng East China Institute of Chemical Technology
    1984, 35(1):  1-10. 
    Abstract ( 634 )   PDF (511KB) ( 215 )  
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    A new plate-to-plate method for performance prediction of azeotropic distillation processes is developed. Azeotropic distillation is characterized by the strong interaction among components and by a small number of components involved. By plate-to-plate method, the number of iterative variables depends only on the number of components, therefore a combination of the plate-to-plate approach and the Newton-Raphson convergence method is suggested for the calculation of azotropic distillation processes. According to the mono-tonicity principle proposed, mole fractions of components or ratios of these fractions are selected as iterative variables to obtain stable and rapid convergences. As a result, this method has been successfully applied for calculating a number of typical azeotropic distillation processes.
    A New Plate-to-plate Method for Calculating Distillation Processes (Ⅳ) Design calculation of multicomponent distillation processes
    Zhang Ruisheng, Le Haihui, Zhu Kaihong and Chen Mingheng East China Institute of Chemical Technology
    1984, 35(1):  11-24. 
    Abstract ( 1199 )   PDF (651KB) ( 169 )  
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    As to multicompoent distillation calculation, most available methods were proposed for operating problems. Although these methods can also be used for design problems, more computer time is needed, since the plate numbers are regarded as iterative variables. In this paper, the authors develop a new plate-to-plate method, which can directly be applied for design purpose and can be used for providing a rigorous solution. Ratios of molar flow rates and mole fractions are chosen as iterative variables. As to ideal systems and those close to ideal ones, these ratios refer to either ratios of molar flow rates of the heavy components or to those of the light components in various plates. As to extractive distillation processes, these ratios refer to the ratios of mole fractions of the components to be seperated in various plates. In comparison with the new plate-to-plate method for performance prediction[1,2] design calculation involves only week loops and more rapid convergence can be achieved without any acceleration or relexation, owing to the disappearance of the strong loop. As a plate-to-plate method, optimal location of feed plates and side-stream plates can easily be determined and no more optimization and any thumb criteria are needed.
    The Sensitivity of Elution Curve to Adsorption and Tranport Coefficients in a SPSR
    Chen Songying, Gao Yinben and Si Qin Shanxi Institute, of Coal Chemistry, Academia Sinica
    1984, 35(1):  25-32. 
    Abstract ( 628 )   PDF (436KB) ( 187 )  
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    The sensitivity of elution curve to adsorption and transport coefficients, analyzed by Fourier analysis, was examined in a Single Pellet String Reactor (SPSR)with the n-pentane-Pt-Sn/Al2O3 system. In these parameters, adsorption equilibrium constant and intraparticle effective diffusion coefficient can be accurately obtained from one pules-response experiment in SPSR. The results show that the behavior of SPSR is similar to that of the conventional packed bed reactor. The effects of the objective function, the period andthe step length used in calculation on the estimated values are also investigated.
    Multicomponent Diffusion Model for Effectiveness Factors of Porous Catalysts (I) Multicomponent diffusion model and numerical computing method
    Zhu Binchen, Song Weiduan, Fang Dingye and Lu Daiqing East China Institute of Chemical TechnologyPresent address: Shanghai Research Institute of Chemica] Technology
    1984, 35(1):  33-40. 
    Abstract ( 756 )   PDF (430KB) ( 185 )  
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    According to the behavior of the combined process of multicomponent molecular diffusion and Knudson diffusion in porous catalysts, a set of second order nonlinear ordinary differential equations describing the concentrationprofiles of reactants and products for a single reaction in an isothermal spherical catalyst has been developed in this paper. In these differential equations, the concentration gradients of different reaction components are strongly coupled together. By using shooting method to solve the two-point boundary value problem posed by this set of equations, the concentration profile of each reaction component and the numerical solution of effectiveness factor can he obtained. Because of the differences between the effective diffusion coefficients of the reaction species, the relations between the changes of their compositions in catalyst no longer obey the stoichiometric relations of the reaction. When the intraparticle diffusion restriction is serious, in the catalyst it may appear a "dead zone", in which the concentrations of the reaction components are asymptotic to the equilibrium concentrations and the chemical reaction practically does not proceed. As the "dead zone" exists, applying this mathematical model and the solution procedure, the radius of "dead zone" and the effectiveness factor under this condition can be solved. The cylindrical sh.ape catalysts commonly used in industry are treated as spheres of equal specific external surface.
    Multicomponent Diffusion Model for Effectiveness Factors of Porous Catalysts (Ⅱ) Effectiveness factors of high-temperature shift reaction catalyst B109
    Zhu Binchen, Song Weiduan, Fang Dingye and Lu Daiqing East China Institute of Chemical TechnologyPresent address:Shanghai Research Institute of Chemical Technology
    1984, 35(1):  41-50. 
    Abstract ( 635 )   PDF (522KB) ( 369 )  
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    According to the multicomponent diffusion model for effectiveness factors of porous catalysts and its numerical computing method proposed by the authors in the first part of this paper, the effectiveness factors of high-temperature shift reaction catalyst B109 have been calculated in the second part, and they are compared with the experimentally observed values. The porosity, pore-size distribution, tortuosity factor and intrinsic kinetics at atmospheric pressure of shift catalyst B109 have been measured, and the global reaction rates only taking account of the intraparticle diffusion in 9.8×8.3mm cylindrical pellets of catalyst B109 under various conditions of gaseous compositions and temperature at atmospheric pressure have been investigated in an internal recycle gradientless reactor. The experimentally observed values of effectiveness factors obtained therefrom under sixteen conditions are from 0.142 to 0.455, and the relative errors of model prediction values with respect to experimentally observed values under the same reaction conditions are in the range of -0.25 to 0.06. The results of comparison are satisfactory.
    The Measurement of Mixing Heat and the Prediction of Vapor-Liquid Equilibrium Data for Hydrocarbon-Alcohol Systems
    Cen Peilin, Zhu Ziqiang Department of Chemical Engineering, Zhejiang University
    1984, 35(1):  51-65. 
    Abstract ( 623 )   PDF (816KB) ( 207 )  
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    Mixing beat data were measured at three different temperatures by PICKER dynamic liquid flow micro-calorimeter for eight binary systems consisting of hydrocarbon and alcohol. A new thermodynamic model-Quasi Chemical Solution Model (QCSM) was suggested to study the thermodynamic properties of hydrocarbon-alcohol systems. The experimental data of mixing heat and isothermal vapor-liquid equilibria of some systems were correlated by the QCSM. The agreements between calculated and experimental data were satisfactory. From QCSM parameters and their relationships with temperature which were fitted in with heat of mixing, the 244 isothermal or isobaric vapor-liquid equilibrium data for 8 hydrocarbon-alcohol binary systems were predicted. Good results were obtained, and the average deviations of vapor phase mole fraction were within 0.004-0.032.
    The Calcuation of Effectiveness Factors of Spherical Catalysts by Weighted Residual Method
    Lin Zhenguo, Shao Nianci and Li Tifei East China Institute of Chemical Technology
    1984, 35(1):  66-71. 
    Abstract ( 512 )   PDF (250KB) ( 225 )  
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    The weighted residual method was used to calculate . the isothermal effectiveness factors of spherical for first- and second-order reactions. Dirac functions were chosen as the weight functions. Because of the simplicity of the form of the trial function, the calculation could be completed with a calculator. The results were very close to the analytic solution for first-order reactions and closer to the numerical solution than those from Satterfield. Kjaer and Bischoff-Aris-Petersen methods for second-order reactions.
    Adsorption Equilibria of C_8 Aromatics in Dietylbenzene
    Huang Chengyu, Liang Shude and Sun Yunyue Department of Chemical Engineering, Zhejiang University
    1984, 35(1):  72-79. 
    Abstract ( 528 )   PDF (355KB) ( 133 )  
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    The adsorption equilibria of C8 aromatics in diethyl benzene were studied by the dynamic method. The adsorption isotherms of paraxylene, orthoxylene, ethylbenzene at 170℃ were determined from the breakthrough curves. Theadsorption isotherms of para- and orthoxylene mixture were determined as well. It turned out that the isotherms follow Henrys law when the concentration is less than 3.0mol/l. The adsorption of two-solute solution can be predicted from the isotherms of the single-solute solution by Radke-Prausnitzs two-dimensional ideal dilute solution theory. The Polanyis adsorption potential theory was used to describe the adsorption equilibria of the paraxylene-diethylbenzene system. The calculated adsorption isotherm at 110℃ from the adsorption data at 170℃ agrees well with the experimental results.
    The Comparison of Different BET-Type Mixed Adsorption Equations with Some Experimental Results
    Gu Tiren Department of Chemistry, Beijing University
    1984, 35(1):  80-84. 
    Abstract ( 524 )   PDF (298KB) ( 441 )  
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    The Busseys BET-type mixed adsorption equations have been applied to adsorption from mixed vapors of cyclohexane-ethanol, benzene-ethanol, and benzene-cyclohexane on Cab-O-Sil at 30℃, and to adsorption from oxygen-nitrogen and oxygen-argon on chromic oxide gel at - 185.6℃. The results are compared with experimental data, and also with authors and Hills BET-type mixed adsorption equations. Since Hills equation is much more complex than Busseys and authors equations, and its predictions are not much different from those of Busseys equation, it is not recommended for application. On the other hand, both the Bussey s and authors equations contain exclusively the parameters of BET equations for single vapors; therefore, they are easy to apply. For some systems the predictions of authors equation are better than those of Busseys equation, while for other systems the reverse is true. Therefore, from the present results, no conclusion can be reached about which is superior.
    By Means of an Approximate Broekhoff Equation for Calculating Pore Size Distribution
    Li Han Tianjin Research Institute of Chemical Industry
    1984, 35(1):  85-92. 
    Abstract ( 491 )   PDF (320KB) ( 106 )  
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    This paper reports a simplified Broekhoff equation for calculating the pore size distribution from adsorption isotherms. The equation is as follows. Where For desorption branch of adsorption isotherms For adsorption branch of adsorption isotherms The results obtained from this equation agree with data from the Broekhoff equation calculated by a computer. The pore size distribution from the authors equation for adsorption branch agrees with that of the desorption branch. Due to this approximation simplified equation a minicomputer may be interfaced to a measuring instrument in use. The application range of the simplified equation is 10 A- 300A.