Please wait a minute...
Table of Content
25 December 1990, Volume 41 Issue 6
    化工学报
    Hollow Fiber Reactor in Backflush Mode for Penicillin Hydrolysis
    Shi Guodong, Yu Xingju and Yuan Quan Dalian Institute of Chemical Physics, Academia Sinica, Liaoning, Dalian
    1990, 41(6):  645-652. 
    Abstract ( 490 )   PDF (388KB) ( 91 )  
    Related Articles | Metrics
    The performance equation for hollow fiber reactor operating in backflush mode is given and checked experimentally by penicillin hydrolysis as a test reaction. The concentration of substrate and cell density are optimized for maximal productivity of reactor. The optimum load of biomass increases with the operating pressure and flux of the membrane, but decreases with the concentration of the substrate.
    A Stochastic Model of Wide Sized Particles in Solid-Liquid Fluidization
    Liu Ziwei, Huang Zhuoshu and Wang Kanghai Changsha Institute of Mining and Metallurgy, Changsha
    1990, 41(6):  653-662. 
    Abstract ( 578 )   PDF (410KB) ( 115 )  
    Related Articles | Metrics
    Axial mixing and segregation were investigated by use of a "rapid section-cutting" fluidized bed. The axial variation oi particle size distribution, mean size and local voidage was measured. The particle motion was found to have random behavior. A random walk mode] was developed by using the Markov Process to characterize mixing and segregation of fluidized wide sizedparticles. Two systems, ilmenite and quartz, were tested with particle size between 0.04 and 0.40mm. The results showed that the minimum fluidization velocity, expansion behavior ot particles, the axial variation of particle size distribution, mean size and local voidagc could be predicted by the model accurately and convienently.
    Heat Transfer Characteristics and Breakdown Criteria of Subcooled Falling Films
    Jiang Zhangyan, Ma Tongze, Zhao Jiaqi and Huo Xiuhe Institute of Engineering Thermophysics, Academia Sinica, Beijing
    1990, 41(6):  663-669. 
    Abstract ( 579 )   PDF (335KB) ( 182 )  
    Related Articles | Metrics
    Simplified physical models and analyses were presented in order to describe heat transfer and breakdown of subcooled liquid films falling down the outside of a vertical tube. On the basis of the analogy of heat transfer in the boundary layer, Nusselt number correlations for convection heat transfer of normal and subnormal films (the latter are films approaching breakdown)were obtained by fitting the test data. The film breakdown patterns were observed in our experiments. The thermocapillary force and the flow regimes seemed to play a dominant role in the film breakdown. Simplified physical models based on the analogy of flooding mechanisms in annular two-phase flow were proposed to describe critical phenomena of film breakdown and some important dimensionless groups could be derived. Ma, Nu; was defined as the breakdown criterion number Bd. Its correlations for temporary and permanent breakdown were obtained by fitting the test data. As a first approximation, the simplified physical models are reasonable and the correlations can be used for predicting breakdown conditions. The experiments were performed under the following parameters: r = 0.207-1.181kg/(m·s), Tin = 19-37℃, and the maximum heat flux was up to 8.67 × 104W/m2.
    Mechanism of Heat Transfer in Dropwise Condensation( I ) Preparation of Alloy Surfaces andHeat Transfer Measurements
    Song Yongji, Zhang Dongchang and Lin Jifang Research Institute of Chemical Engineering, Dalian University of Technology, Liaoning, Dalian
    1990, 41(6):  670-675. 
    Abstract ( 583 )   PDF (276KB) ( 260 )  
    Related Articles | Metrics
    The experiments on the mechanism of dropwise condensation were conducted on copper alloy surfaces with steam. These surfaces were processed with ion-implantation technique. The implanted element were N, Ar, He and O. Steady dropwise condensation was obtained for all the surfaces.The results showed that heat transfer efficiency of Cu-N surface was better than the others. Compared with filmwise condensation the heat transfer coefficient of dropwise condensation increased by 15-20 times and heat flux increased by 3-4 times. A discussion on the causes of heat transfer improvement was given.
    Mechanism of Heat Transfer in Dropwise Condensation(Ⅱ) Measurements of Drop-size Distribution, Drop Growth Rate and Drop Departure Diameter
    Song Yongji, Zhang Dongchang and Lin Jifang Research Institute of Chemical Engineering, Dalian University of Technology, Liaoning, Dalian
    1990, 41(6):  676-682. 
    Abstract ( 629 )   PDF (363KB) ( 245 )  
    Related Articles | Metrics
    The processes of dropwise condensation of steam on various copper alloy surfaces were recorded by high speed photography.The obtained negatives were analyzed by digital image processing. The results of drop-size distributions, drop growth rates and drop departure diameters under different conditions were derived, and analyzed. The drop size distribution can be expressed as N(D) = AD-B. It was mainly affected by surface properties and was little affected by operation conditions. The growth rate of a small drop was controlled by steam condensing rate, and coalescence among drops was the dominant reason of big drop growth. The drop departure diameter was determined by condensation surface properties. Operation conditions has little influence on drop departure diameter but had obvious effect on drop growth rate.
    Mechanism of Heat Transfer in DropwiseCondensation (Ⅲ) Physical Model of DropwiseCondensation and Comparison betweenTheoretical and Experimental Results
    Song Yongji, Zhang Dongchang and Lin Jifang Research Institute of Chemical Engineering, Dalian University of Technology, Liaoning, Dalian
    1990, 41(6):  683-688. 
    Abstract ( 562 )   PDF (231KB) ( 106 )  
    Related Articles | Metrics
    Assuming that vapor adsorption plays a major role during dropwise condensation, a physical model based on the coexistence of drops and film has been developed. A heat transfer coefficient correlation was derived by theoretical analysis. The comparison between theoretical calculation and experimental results of the heat transfer coefficient was quite satisfactory. The calculated results indicated that heat was mainly transferred through microdrops and the film region. The film accounted for about 15%-25% of the total area and accounted ior about 85%-95% of the total heat energy transferred.
    Gas Oil Pyrolysis Reaction and Coke-formation Models with Coking Inhibitor
    Zou Renjun, Lou Qiangkun, Li Heping and Mo Sihong Hebei Institute of Technology, Tianjin
    1990, 41(6):  689-694. 
    Abstract ( 544 )   PDF (282KB) ( 105 )  
    Related Articles | Metrics
    Gas oil pyrolysis reaction and coke-formation with coking-inhibitor YZS1 has been studied. A pyrolysis kinetics model of gas oil with added coking-inhibitor YZS1 is developed by considering the influence of coking-inhibitors upon the reaction kinetics of pyrolysis and developing a new reaction scheme of pyrolysis. Ethylene, propylene and aromatics are proved to be as the coke precursors in the pyrolysis of gas oil. A simplified coke-formation kinetics model of gas oil pyrolysis is proposed and its kinetic parameters are estimated.
    The Thermodynamics of Concentrated NonaqueousStrong Electrolyte Solutions——Vapor-LiquidEqulibrium of Hydrochloride-Methanol Mixture
    Lu Xiaohua, Wang Yanru and Shi Jun Nanjing Institute of Chemical Technology, Nanjing
    1990, 41(6):  695-701. 
    Abstract ( 550 )   PDF (339KB) ( 124 )  
    Related Articles | Metrics
    A new method for the calculation of vapor-liquid equilibrium (VLE) of nonaqueous volatile strong electrolyte solutions has been developed. This method is demonstrated by comparing calculated data with experimental results of HC1-CH3OH system. The activity coefficients of HC1 and CH3OH at 298.15K can be satisfactorily correlated up to 8 molality by estimating the ionic association constant Kx = 1.7×l02 and the short-range-force parameter W=-2.15 with the association model of Pitzer and Li (1984). After deriving the temperature dependence of both the model parameters and the Henrys constant of HC1 in methanol, it is possible to predict the VLE for HC1-CH3OH system at 101.3kPa and about 340K. The mean deviation of boiling points and vapor phase mole fractions between measurements of this study and calculated results are 0.73K and 0.0014 respectively.
    Liquid-Liquid Extraction of Proteins by Using AOT-Phospholipid Reverse Micelle System
    Shi Hongqin, Lei Xia and Shen Zhongyao Department of Chemical Engineering, Tsinghua University, Beijing
    1990, 41(6):  702-708. 
    Abstract ( 539 )   PDF (353KB) ( 108 )  
    Related Articles | Metrics
    The water contents (Wo) of reverse micelles formed in a polar solvents by the addition of phosphatidylcholine(PC), phosphtidylethanolamine(PE)and the mixed system PC/AOT and PE/AOT have been studied. In a reverse micelle system Wo reflects the micelle size. The performance of extraction of proteins by these system has also been investigated. An assay was developed to determine the protein concentration in apolar phase in the presence of PC or PE. It was shown that the reverse micelles formed by PC or PE could not extract lysozyme, ribonuclease-a and cytochrome-c. The results of Wo measurement indicated that adding PC or PE to AOT reverse micell system made the reverse micelles much larger. Adding PE to AOT reverse micelle system increased the solubilities of some proteins in apolar phase, while adding PC to AOT system usually decreased the solubilities. It seems that the main factor affecting the extraction of proteins by reverse micelles is not the size of reverse micelle, but the interaction between the micelle and the proteins.
    Radial Distribution of Heat Transfer Coefficient in Fast Fluidized Bed
    Bi Hsiaotao, Jin Yong, Yu Zhiqing and Bai Dingrong Department of Chemical Engineering, Tsinghua University, Beijing
    1990, 41(6):  709-717. 
    Abstract ( 584 )   PDF (406KB) ( 122 )  
    Related Articles | Metrics
    This paper presents an experimental study on the radial distributions of heat transfer coefficients in a fast fluidized bed operating at low temperatu re. The following conclusions can be reached from the experimental results: 1. The heat transfer coefficient profiles are complex in a fast fluidized bed, generally, flat in the centre and steep in the region near the bed wall. 2. Solids concentration is the dominant factor influencing heat transfer, while the effect of gas and particle velocities is comparatively less significant. 3. When solids concentration is high, the heat transfer coefficient profile is consistent with that of solids concentration. For low solids concentration, the profile is affected by the radial distribution of gas and particle velocities, and a minimum point of heat transfer coefficient will appear in the region of radial ratio from 0.5 to 0.8. For rather low solids concentration and high gas velocity, gas convection becomes notable, the heat transfer coefficient profile becomes more complex with higher values in the region near the axis than those near the bed wall. The following equation is recommended to correlate the local heat transfer coefficients in fast fluidized beds: where a, n,1 and n2 are functions of radial positions, while ε is a function of axial position
    Radial and Axial Dispersion of Liquid in Three-Phase Fluidized Beds
    Zhao Xueming, Wang Yiping, Hu Zongding and Jia Tingxun Department of Chemical Engineering, Tianjin University, Tianjin
    1990, 41(6):  718-722. 
    Abstract ( 510 )   PDF (220KB) ( 164 )  
    Related Articles | Metrics
    Radial and axial mixing phenomena in a large three-phase fluidized bed can be described by the two-dimensional dispersion model. The model was analysed with a unsteady pointsource trace injection. The appropriate position for tracer measurement was determined according to simulation results. The tracer concentrations were measured by a special multichannel micro-probe. The radial and axial dispersion coefficients can be simultaneously estimated by using least-squares analysis in the time domain. In order to compare the, dispersion coefficients in different systems, the tracer experiments were done in a single liquid phase system, a liquid-solid two-phase system and a gas-liquid-solid three-phase system. In the single liquid phase system, both radial and axial dispersion coefficients were very small. In the liquid-solid two-phase fluidized beds, these dispersion coefficients were much higher than those in single liquid system. The radial dispersion coefficients of liquid in three-phase fluidized beds were greatly increased by the rising bubbles and moving particles.
    Evaluation of Transport and Adsorption Coefficientsof Porous Catalyst in Fixed-bed Reactors byImproved Curve Fitting in Time Domain
    Zhang Renyou, Bao Ziran, Wang Furong, Li Dianqing and Zhu Zhuoqun Beijing Institute of Chemical Technology, Beijing
    1990, 41(6):  723-731. 
    Abstract ( 480 )   PDF (384KB) ( 124 )  
    Related Articles | Metrics
    Boersma-Klein and Moulijn evaluated the transport coefficients of non-adsorption system by a new method-the improved curve fitting domain. in time which combines Fourier analysis with the traditional curve fitting in time domain, and substitutes the error map plotting with a set of computer program of linear and non-linear regression. In this paper, the calculations of Fourier analysis and the curve fitting in time domain are based on the simplex method of polydimensional search technique, which means the simplification of the work of Boersma-Klein et al. Moreover, the application of the improved curve fitting in time domain is extended to adsorption system, and five transport and adsorption coefficients of domestic C301 methanol synthesis catalyst in fixed-bed reactors are obtained. The advantages of this method and the selection of harmonic number and period for its use are also discussed.
    A Study on Poly (vinyl chloride) Blends with Poly (ethylene-CO-vinyl acetate)
    Li Huilin, Wang Qi, Guo Shaoyun and Xu Xi Polymer Research Institute, Chengdu University of Science and Technology, Chengdu
    1990, 41(6):  732-739. 
    Abstract ( 553 )   PDF (386KB) ( 234 )  
    Related Articles | Metrics
    The experimental results show that the impact strength of PVC/EVA blend strongly depends on EVA content, blending temperature and blending time. It reaches a maximum at 10 parts of EVA per 100 parts of PVC, and will be further increased when PE is added in. TEM observation confirms that the formation of EVA continuous network in PVC/EVA is responsible tor the high impact strength of the blend. EVA could promote the gelation of PVC, while PE could reduce the apparent viscosity of the Mend and has a delayed action on the gelation of PVC. A series of mathematic models are established by means of binary linear regression to correlate the melt viscosity of the blend with both shear stress and temperature. The flow activation energy of PVC/EVA decreases with increasing EVA content. The addition of EVA re-duces the non-Newtonian flow index, indicating the increased dependence of the melt viscosity of the blend on the shear stress.
    Phase Equilibrium of NH_3-CO_2-H_2O-NH_2CONH_2 System at High Temperature and Pressure in Urea Synthesis
    Hu Liegi, Wei Boyi and Shen Huamin Shanghai Research Institute of Chemical Industry, Shanghai
    1990, 41(6):  740-744. 
    Abstract ( 550 )   PDF (236KB) ( 100 )  
    Related Articles | Metrics
    A new thermodynamic model for ammonia-carbon dioxide-water-urea system at the condition of urea synthesis (T=438.15-478.15K, P=6.87-24.5 MPa, NH3/CO2 = 2.6-5.0, H2O/CO2= 0.2-1.2) is established on the basis of experimental data. Perturbed-hard-sphere equation of state and Wilson equation are use to treat the non-idealities of vapor and liquid phases. Correlations of the experimental data at 433.15K,438.15K,448.15K, 458.15K, 468.15K and 478.15K are made with this model. The mean relative deviation of molar fraction of ammonia and carbon dioxide in vapor phase is 3.05% and 8.27% respectively, and the mean relative deviation of total pressure is 3.31%. The calculated values of pressure with this mode] are in agreement with those of industrial synthesis of urea.
    Gas-Liquid Two Phase Flow Patterns in Thin Rectangular Channels
    Si Qin, Wang Huijin and Huang Hongding Department of Chemical Engineering Tianjin University, Tianjin
    1990, 41(6):  745-753. 
    Abstract ( 568 )   PDF (356KB) ( 107 )  
    Related Articles | Metrics
    Gas-liquid two phase flow patterns were studied in two thin rectangular channels made of plexiglass. One of the channels is 1000mm in height, 140mm in width and 4mm in thickness, and the other 1000mm in height, 140mm in width and 8mm in thickness. Air-water was used as working media, which flow upward in the rectangular channels. Bubble flow, slug flow, churn flow and annular flow were found both by visual observation and by photography. They were basically similar to the flow patterns in a vertical circular tube. The flow pattern maps were plotted as 1/Xtt versus G, and Jg* versus RL. The former is similar to the flow pattern maps in a vertical circular tubeproposed by J. R. Fair. However, the ranges oi flow region are different. The following expression was obtained by regression of the experimental data The equation can be used to determine the transition region from one type of flow pattern to another. The coefficient K and the index n in the equation are related to the flow region and are dilferent in different flow regions. The pressure drop was measured by using a x-y functional register. The variation in the frequency and amplitude of pressure drop changes with different flow patterns. The pressure drop spectrum can be used to determine flow patterns qualitatively. The pressure drop of gas-liquid two phase flow in thin rectangular channels was calculated with the Lockhart-Martinelli method. The results obtained were compared with the experimental data.
    Calculation of Detachment Diameter of A Nozzle Bubble
    Li Qien Research Institute of Chemical Engineering South China University of Technology, Guangzhou
    1990, 41(6):  754-761. 
    Abstract ( 563 )   PDF (343KB) ( 216 )  
    Related Articles | Metrics
    According to the configuration of a real nozzle bubble, the author proposes a physical model which describes the nozzle bubble as a tadpole structure. Unlike a spherical bubble, the long tail part of a tadpole bubble has great influence on the inertia force and the drag force acting on the bubble. Thereupon, the author discusses the bouyancy force, the inertia force, the drag force and the surface tension force acting on a nozzle bubble in equilibrium before detachment takes place. An iteration equation for calculating bubble detachment diameter is estableshed which contains all the important factors of the liquid phase physical properties, the nozzle diameter and the gas rate. The calculated detachment diameter is in good agreement with experimental observations in almost all ranges of the above mentioned parameters. Various individual cases are calculated with high accuracy by this iteration equation as compared with equations of other investigations, and the causes of deviation oi the latter ones are discussed.
    Effect of Entrainment on Tray Efficiency of Distillation Columns
    Liu Xiunan and Lu Xiulin Department of Chemical Engineering, East China University of Chemical Technology, Shanghai
    1990, 41(6):  762-768. 
    Abstract ( 731 )   PDF (278KB) ( 317 )  
    Related Articles | Metrics
    A new correlation of tray efficiency has been derived under completemixing of liquid on the tray for taking into account the effiect of entrainment where EM is the tray efficiency based on vapor phase in the absence of entrainment and EMa is the tray efficiency considering the effect of entrainment. This correlation is more accurate when the liquid on the tray is completely mixed and it can be simplified to the well-known Colburns equation at λo=1. The calculated results are compared with those from Colburn s equation and it is shown that the errors are smaller than those of Colburns equation for all three cases listed by Lockett.