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Table of Content
25 April 1997, Volume 48 Issue 2
    化工学报
    KINETICS OF ENZYMATIC SYNTHESIS OF CEPHALEXIN IN REVERSE MICELLES
    Shi Yifeng, Yu Xingju and Yuan Quan(Dalian Institute of Chemical Physics , Chinese Academy of Sciences , Dalian 116012)
    1997, 48(2):  129-135. 
    Abstract ( 565 )   PDF (344KB) ( 210 )  
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    The acylase from Xanthomanas citri was used to synthesize cephalexin (CEX) from 7 - amino- 3 - deacetoxy - cephalosporanic acid (7 - ADCA) and D - α - phenylglycine methyl ester (PGM) as a kinetic controlled condensed reaction. However, X. citri enzyme catalyzes not only CEX synthesis but also PGM hydrolysis and CEX hydrolysis. The results on a rational analysis of the reaction mechanisms showed that higher activity and higher ratio of transferase to hy-drolase activity are favorable for use in reverse micelles system. The enhancement effect of CEX synthesis parallel with avoiding hydrolysis of PGM and CEX was found when X. citri enzyme was solubilized in AOT/isooctane reverse micelles. The enzyme activity in reverse micelles is governed by the hydration ratio as bell- shaped dependence.
    VAPOR - LIQUID EQUILIBRIA FOR CFC ALTERNATIVES
    Cao Wenjun, Yu Hui and Wang Wenchuan(College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029)
    1997, 48(2):  136-142. 
    Abstract ( 647 )   PDF (328KB) ( 205 )  
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    A set of experimental equipment consisting of both vapor and liquid recycling flowsheet was established. Tested with a known system, the equipment was proved reliable for vapor -liquid equilibrium measurements under elevated pressures. Vapor - liquid equilibria for the binary systems, HCFC22 + HCFC 142b, at 313. 15 K, 322. 80 K and 328. 15 K, and HFC22 + HFC152a, at 313. 15 K, and 328. 15 K were measured, respectively. In addition, vapor- liquid equilibria for a ternary system, HCFC22 + HFC152a + HCFC142b at 313.15 K, 323.15 K, 328. 15K, and 338. 15K were also reported. All the results were correlated by using the Peng Robinson equation of state with satisfactory accuracy.
    INTERPRETATION AND PREDICTION OF THE NONIDEAL BEHAVIORS OF ELECTROLYTE SOLUTIONS
    Wang Renyuan and Shi Jun(Department of Chemical Engineering, Nanjing University of Chemical Technology, Nanjing 210009)
    1997, 48(2):  143-151. 
    Abstract ( 582 )   PDF (467KB) ( 155 )  
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    A new theory of electrolyte solutions is presented. The nonideal behaviors of electrolyte solutions are interpreted from the energy effects of the particle interactions and the entropy effects of the microstructures of the solutions. A new primitive model of electrolyte solutions is developed. The model containing the contribution of the entropy effect gets significant improvement in the prediction of the nonideal behaviors of various electrolyte solutions.
    INCIPIENT FLUIDIZATION CONDITION IN A CENTRIFUGAL FLUIDIZED BED (Ⅰ) FUNDAMENTAL THEORY
    Hao Yingli and Shi Mingheng(Department of Power Engineering, Southeast University, Nanjing 210096)
    1997, 48(2):  152-159. 
    Abstract ( 560 )   PDF (359KB) ( 190 )  
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    The equations to calculate incipient fluidizing velocities, pressure, voidage, interstitial gas velocity, bed expansion and pressure drop in centrifugal fluidized beds are obtained by simplifyirg and solving the governing equations based on the interacting continua theory. The predictions of the pressure drop across the bed and the critical fluidizing velocity agree well with the expeririental results. The theoretical analyses show that the granules centrifugal fluidized bed is gradually fluidized layer by layer, from the inner surface outward, in the range of the gas velocities. When fluidization is achieved, the fluidization degree for each bed layer at the different radial positions is different. The influences of gas compressibility on the behaviour of the bed increase with the increase of rotational speed of bed.
    INCIPIENT FLUIDIZATION CONDITION IN A CENTRIFUGAL FLUIDIZED BED ( Ⅱ) EXPERIMENTAL STUDIES
    Hao Yingli and Shi Mingheng( Department of Power Engineering, Southeast University, Nanjing 210096)
    1997, 48(2):  160-165. 
    Abstract ( 596 )   PDF (273KB) ( 202 )  
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    The experimental studies on the flow characteristics in centrifugal fluidized beds were performed. The results indicated that the pressure drop exhibited a plateau when the flow rate decreased. But when the flow rate increased the influences of the bed structure, the way of loading bed material and the operating condition on the curve of pressure drop-velocity were relatively great. The curve obtained when the flow rate decreased should be used to determine the incipient fluidizing velocities experimentally. The visual experimental studies verified that the bed was gradually fluidized layer by layer with the increase of flow rate in the incipient fluidization stage, and indicated that the granular material was fully mixed in the fluidized region of the bed.
    A DYNAMIC NONEQUILIBRIUM STAGE MODEL OF MULTICOMPONENT DISTILLATION PROCESSES
    Qin Yongsheng, Xu Yongmao and Fang Chongzhi(Department of Automation, Tsinghua University, Beijing 100084)Tang Jie(Tianjin Petrochemical Company, Tianjin 300217)
    1997, 48(2):  166-174. 
    Abstract ( 985 )   PDF (412KB) ( 258 )  
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    A dynamic nonequilibrium stage model of multicomponent distillation processes is developed in this paper. Mass and energy transfer rate equations are used in describing the transfer processes on real trays and thus the computations of stage efficiencies are entirely avoided. By in-troducinga separation efficiency function, an applicable simulation model of simple structure is presented and the procedure for solving the differential equations using Gears algorithm is depicted as well. The simulation results obtained from two industrial distillation columns show that, comparing with the experimental data, this model can really predict the dynamics on real trays.
    ESTABLISHMENT AND APPLICATION OF RELATIVE COST FUNCTION FOR MULTICOMPONENT SEPARATING COLUMN SERIES
    Shi Baochang and Wang Jianhong(College of Chemical Engineering , Beijing University of Chemical Technology, Beijing 100029)
    1997, 48(2):  175-179. 
    Abstract ( 589 )   PDF (218KB) ( 226 )  
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    Through a large amount of strict simulated calculation and induction, a more reasonable relative cost function F is proposed to replace CFS. Hence the practicability, reliability and suitability of the heuristic method in the establishment of separating column series can be improved.
    DRYOUT CHARACTERISTICS IN HORIZONTAL HELICALLY COILED TUBE
    Feng Ziping, Guo Liejin, Chen Xuejun and Sun Jufeng(National Laboratory of Multiphase Flout in Power Engineering) (Xian Jiantong University, Xian 710049)
    1997, 48(2):  180-185. 
    Abstract ( 646 )   PDF (306KB) ( 181 )  
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    A study of the dryout characteristics in forced convection boiling in electrically heated horizontal helically coiled tube is reported. The results demonstrate that dryout usually occurs at the front (θ= 90°)and back side (θ= 270°) of the exit cross - section. The secondary flow induced by centrifugal force and the wall heat conduction around the dryout points are the dominant mechanisms of dryout in a helically coiled tube. Based on the experimental data, a correlation for predicting the critical dryout quality of horizontal helically coiled tube is proposed.
    A MODEL OF FREEZE DRYING OF FOODS AND SOME INFLUENCE FACTORS ON THE PROCESS
    Tu Weiping, Cheng Jiang, Yang Zhuoru and Chen Huanqin(Chemical Engineering College, South China University of Technology, Guangzhou 510641)
    1997, 48(2):  186-192. 
    Abstract ( 674 )   PDF (291KB) ( 216 )  
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    A simplified mathematical model of freeze drying has been developed and solved by using Crank - Nicholson method . With the experiments of freeze drying for carrot and potato chips, the effects of parameters such as the heat transfer patterns, the heating temperatures and pressures on the freeze drying time were discussed. The experimental results obtained agreed well with those calculated by the model.
    INVESTIGATION OF MACRO - MIXING PROCESS FOR JET - ENTRAINED GASIFIER ( Ⅰ) COLD MODEL CONCENTRATION DISTRIBUTION
    Wang Fuchen, Yu Guangsuo, Gong Xin, Wu Tao and Yu Zunhong(College of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237)
    1997, 48(2):  193-199. 
    Abstract ( 645 )   PDF (318KB) ( 187 )  
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    In this paper, the concentration distribution of jet - entrained gasifier is measured in a large scale cold model (1000 mm ×4000 mm) gasifier based on the twin - fluid concentric intersective jet nozzle. The effect of the momentum ratio of annular jet to concentric jet on macro - mixing process is also investigated. The variation of dimensionless concentration, dimensionless maximum concentration, centre mixing fraction and dimensionless concentration half - radius is proposed.
    INVESTIGATION OF MACRO - MIXING PROCESS FOR JET - ENTRAINED GASIFIER (Ⅱ) COLD MODEL RESIDENCE TIME DISTRIBUTION
    Wang Fuchen, GongXin, Wu Tao, Yu Guangsuo and Yu Zunhong(College of Resource and Environmental Engineering, East China University of Science ami Technology, Shanghai 200237)
    1997, 48(2):  200-207. 
    Abstract ( 484 )   PDF (321KB) ( 158 )  
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    In this paper, the residence time distribution of jet - entrained gasifier is measured in a large scale cold model (1000 mm × 4000 mm) gasifier based on the twin - fluid concentric intersective jet nozzle. Post by - pass mixing model for the residence time distribution in gasifier is constructed based on the network synthesis technique and the explicit mathematic equation of that has been obtained. The relationship of the model parameter with dimensionless similarity number Ct and the momentum ratio of annular jet flow to concentric jet flow Gr is also given in the experiment conditions.
    STUDY ON SHOCK WAVE FORMATION, ITS EFFECTING AND PREVENTION IN GRINDING PROCESS FOR JET MILL
    Liu Dongsheng,Li Fengsheng,Song Hongchang,Li Chunjun and Liu Fengbiao( Ultrafine Pcrwder Technology and Surface Science Institute, Nanjing University of Science and Technology, Nanjing 210014)
    1997, 48(2):  208-213. 
    Abstract ( 523 )   PDF (270KB) ( 169 )  
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    In this paper, the reasons of shock wave formation in a jet mill are analyzed firstly. Then the influence of the shock wave on impact velocity of particle is discussed by numerical method. Finally some suggestions are presented to prevent from shock wave formation in the grinding process.
    OPTIMAL REGRESSION OF KINETICS MODEL FOR STYRENE POLYMERIZATION IN A SFR
    Cao Guiping, Zhu Zhongnan, Le Huihui and Zhang Minghua(State Key Lab of Chemical Engineering, East China University of Science and Technology, Shanghai 200237)Lu Xiwen(Department of Applied Mathematics, East China University of Science and Technology, Shanghai 200237)
    1997, 48(2):  214-220. 
    Abstract ( 590 )   PDF (324KB) ( 112 )  
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    In the regression of kinetics model for radical polymerization in a "starved feed" reactor, there are three objectives which have the same status: mass ratio of monomer vs. solvent, solids fraction and number average molecular weight. For the multiple-objective plan, three objective functions are presented and an optimal model of kinetics parameters is set up. The result shows that the model value fits very well with the experimental value. The analysis of objective functions sensitivity to model parameters shows that: kp/ k10~(1/2)and α are more sensitive and initiator efficiency is less sensitive.
    MODIFIED SRK EQUATION OF STATE TO IMPROVE PREDICTION OF SATURATED VAPOR PRESSURES AND SATURATED VOLUMES OF ALKANES
    Zheng Daqing( University of Petroleum , Beijing 102200)
    1997, 48(2):  221-226. 
    Abstract ( 641 )   PDF (226KB) ( 137 )  
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    SRK equation of state(EOS) is modified to improve the prediction of vapor pressures and saturated liquid volumes of alkanes (C1 -C20). The new generalized correlations for calculating the parameters n and m in the α ( T) function as well as C and S used for volume translation method are proposed. The modified SRK EOS is applicable for calculating the vapor pressures and saturated volumes from friple point to critical point, and it has been compared with SRK, PR, TVDW, PT, SW and Lee - Kesler empirical correlation.
    THE CORRELATION BETWEEN THERMODYNAMIC PROPERTIES AND MOLECULAR TOPOLOGICAL INDEX OF ALKANES
    Ni Caihua and Feng Zhiyun(Department of Chemistry, Jingzhou Teachers College, Jingsha 434100)
    1997, 48(2):  227-231. 
    Abstract ( 494 )   PDF (225KB) ( 97 )  
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    Connectivity indices of 85 alkanes were calculated based on the definition of M. Randic. The properties such as the standard enthalpies of formation, the standard entropies and the standard free energies of formation of these alkanes were correlated with the connectivity indices and the number of carbon atoms. A general equation was proposed as follows; P = a X + bN + c. The thermodynamic properties calculated for both gasous and liquid states of the 85 alkanes are in excellent agreement with the experimental values through regression analysis.
    EXPERIMENTAL STUDY OF TWO - PHASE FLOW INSIDE FINNED - TUBES SEPARATOR USING 3-D - PDA
    Liang Shaorong, Shen Yueiiang, Yan Jianhua, Li Xiaodong, and Cen Kefa(Institute for Thermal Pouer Engineering, Zhejiang University, Hangzhou 310027)
    1997, 48(2):  232-236. 
    Abstract ( 518 )   PDF (243KB) ( 87 )  
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    By using a three-dimension particle dynamics analyzer (PDA), cold model experimental study on the characteristics of gas-solid two-phase flow around the finned-tube, the element of impact separator used in circulating fiuidized bed boiler (CFBB), was conducted. The distributions of velocity, turbulent intensity, particle size and solid concentration of gas-solid two-phase flow around finned tube were obtained. The effects of upstream velocity and finned tube structure on fluid characteristics were also considered. The measured results built a sound base for gas-solid separating mechanism research and structure optimization design of finned-tube separator.
    INFLUENCE OF THE PORE STRUCTURE AND GAS HUMIDITY ON DESULFURIZATION BY IMPREGNATED ACTIVATED CARBON
    Tan Xiaoyao, Wu Diyong and Yuan Quan(Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116012)
    1997, 48(2):  237-240. 
    Abstract ( 583 )   PDF (165KB) ( 200 )  
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    The effects of the pore structure of activated carbon and the humidity of inlet gas on desulfurization activity have been investigated. The experimental results showed that the pores within the range from 1 nm to 5 nm had the best desulfurization activity, and the relative humidity of inlet gas should be within 0. 85 -0. 95. These operating conditions are beneficial to increase in the volume of the water film, which favors improving the desulfurization rate and sulfur capacity.
    LOCAL CONTRIBUTION METHOD FOR PLATE EFFICIENCY
    Xu Songlin,Wang Shuying and Yu Guocong(K.T. Yu)(Chemical Engineering Research Center, Tianjin University, Tianjin 300072)
    1997, 48(2):  241-246. 
    Abstract ( 566 )   PDF (236KB) ( 123 )  
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    The measurement of flow pattern on a sieve tray reveals that there exist a reversed flow zone near the inlet weir, a slow flow zone with circulation at the segmental sides of tray and an unevenly distributed main flow zone. Based on the measurement of liquid flow distributions,a simple hybrid model for plate efficiency was suggested. Comparison between the prediction by the present model and the others from literature shows that the present one is sufficiently accurate.
    INFLUENCE OF THE N - SOURCE CONCENTRATION ON XANTHAN FED - BATCH FERMENTATION
    Zhao Xueming, Ma Hongwu, Huang Xiao and Ban Rui(Department of Chemical Engineering, Tianjin University, Tianjin 300072)
    1997, 48(2):  247-251. 
    Abstract ( 600 )   PDF (247KB) ( 177 )  
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    Using (NH4)2SO4 as the N - source, the effect of the initial N - source concentration on xanthan fed - batch fermentation was studied. The best concentration was about 4 gdddddddddddL-1. This result was compared with previous studies. The oxygen limitation and the stagnant zone might be the main reason for the decrease of the production rate in high cell concentration. By improving the oxygen supply capacity of the equipment, optimizing the N - source concentration and fed- batch control of glucose concentration, xanthan concentration achieved 40 gddddddddddL-1 in 55 hours.
    PREPARATION AND PURIFICATION OF FULLERENES FROM METALLURGICAL COKE
    Qiu Jieshan,Zhou Ying, Zhang Hongbing and Luo Changqi(Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012)Zhou Hongyi(College of Technical and Vocational Education ,Zhejiang University of Technology,Hangzhau 310014)
    1997, 48(2):  252-256. 
    Abstract ( 666 )   PDF (275KB) ( 273 )  
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    Fullerene has been prepared from four commercial cokes by electrical arcing in helium atmosphere and purified by column chromatography using activited carbons as the stationary phase. The crude and pure fullerene products are characterized by high pressure liquid chromatography, mass spectrometry and UV-Vis spectrometry. The results are discussed in terms of the carbon arc evaporation process parameters and the properties of coke. The yield of crude fullerenes decreased as the volatile matter content of coke increases and the composition of crude fullerenes depends on the volatile matter content of coke. After column chromatography separation with pure toluene as mobile phase on active carbon-silica gel, 99. 9% C60 is obtained. The yield of pure C60 is affected by the microstructure of active carbon and the length of column chromatography.