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SCI和EI收录∣中国化工学会会刊
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Table of Content
28 August 2002, Volume 10 Issue 4
    RESEARCH PAPERS
    Studies on the Mechanism of Primary Nucleation of Ciprofloxacin Hydrochloride Monohydrate
    WANG Jingkang, LIU Yong, YIN Qiuxiang
    2002, 10(4):  375-380.  doi:
    Abstract ( )   PDF (2012KB) ( )  
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    A general expression for the relationship between induction period and supersaturation was
    developed based on polynuclear approach. Different mechanism of primary nucleation in
    solution can be illustrated by the expression. The results of induction period determined
    by laser scattering method shows that the crystallization of ciprofloxacin hydrochloride
    monohydrate in water/ethanol or aqueous solution is by the mechanism of primary nucleation
    followed by one-dimensional diffusion growth, and then one-dimensional continuous or "birth
    and spread"growth on crystal face. The growth mechanism on the crystal face is affected by
    temperature and solvent.
    Large-eddy Simulation of Bubble-Liquid Confined Jets
    YANG Min, ZHOU Lixing, L. S. Fan
    2002, 10(4):  381-384.  doi:
    Abstract ( )   PDF (1678KB) ( )  
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    The Large-eddy simulation (LES) with two-way coupling is used to study bubble-liquid two-
    phase confined multiple jets discharged into a 2D channel. The LES results reveal the
    large-eddy vortex structures of both liquid flow and bubble motion, the shear-generated and
    bubble-induced liquid turbulence, and indicate much stronger bubble fluctuation than that
    of the liquid, the enhancement of liquid turbulence by bubbles. Both shear and bubble-
    liquid interaction are important for the liquid turbulence generation in the case studied.
    Numerical Simulation of Gas-Liquid Flow in a Stirred Tank with a Rushton Impeller
    WANG Weijing, MAO Zaisha
    2002, 10(4):  385-395.  doi:
    Abstract ( )   PDF (3435KB) ( )  
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    The gas-liquid flow field in a stirred tank with a Rushton disk turbine, including the
    impeller region,was numerically simulated using the improved inner-outer iterative
    procedure. The characteristic features of the stirred tank, such as gas cavity and
    accumulation of gas at the two sides of wall baffles, can be captured by the simulation.
    The simulated results agree well with available experimental data. Since the improved
    inner-outer iterative algorithm demands no empirical formula and experimental data for the
    impeller region, and the approach seems generally applicable for simulating gas-liquid
    stirred tanks.
    An Experimental Study of the Flowrate Transients in Slug Flow
    HE Limin, GUO Liejin, CHEN Xuejun, CHEN Zhenyu, KOU Jie
    2002, 10(4):  396-403.  doi:
    Abstract ( )   PDF (2605KB) ( )  
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    An investigation of the characteristics of flowrate transients within slug flow was
    conducted in a largescale outdoor testing facility. The test section consisted of a 378 m
    long, 7.62 cm diameter stainless steel pipe.Air and water were used as the test fluids. The
    response to a change of flowrate of either phase or two phases was measured using a series
    of pressure transducers and differential pressure transducers. An increase or decrease in
    gas flowrate caused a pressure overshoot above the value at new steady state or led to a
    pressure undershoot to form a temporary stratified flow. Pressure waves existed in the
    pipeline, spreading from the entrance to the exit. The magnitude of pressure overshoot in
    "up-gas" transient or of pressure undershoot and period of the temporary stratified flow in
    "Down-gas" transient are related to the change of gas flowrate and the distance away from
    the entrance. In contrast, the change in liquid flowrate was accommodated by smooth
    transitions between the corresponding steady states, and only one obvious change was found
    in the slug frequency. According to experimental results, the pressure overshoot, pressure
    undershoot and the pressure wave propagation were analyzed,and the phenomena were explained
    reasonably. Some correlations for the calculation of the pressure overshoot and undershoot
    were proposed.
    Wall-liquid mass transfer for Taylor bubbles rising through liquid in a vertical tube
    YUN Junxian, SHEN Ziqiu, MING Pingwen
    2002, 10(4):  404-410.  doi:
    Abstract ( )   PDF (2122KB) ( )  
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    Wall-liquid mass transfer for Taylor bubbles rising through liquid column in vertical tubes
    is an important and fundamental topic in industrial processes. In this work, the
    characteristics of wall-liquid mass transfer for this special case of slug flow were
    studied experimentally by limiting diffusion current technique (LDCT). Based on the
    experimental results and the analysis of hydrodynamic mechanisms, it was proposed that four
    different zones exist, i.e. the laminar falling film zone, the turbulent falling film zone,
    the wake region and the remaining liquid slug zone. The corresponding correlations for all
    these zones were developed.
    Equilibrium of Extraction of p-Aminobenzenesulfonic Acid by Aliquat 336
    LI Zhenyu, QIN Wei, DAI Youyuan
    2002, 10(4):  411-415.  doi:
    Abstract ( )   PDF (1592KB) ( )  
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    p-Aminobenzenesulfonic acid was selected as a typical solute with amphoteric functional
    groups to be separated from dilute solution. A quaternary ammonium chloride, Aliquat 336,
    was used as the extractant.The effects of pH, extractant concentration and diluent types on
    distribution coefficient, D, were investigated.Meanwhile, the ion exchange reaction for
    Aliquat 336 with p-aminobenzenesulfonic acid in the extraction process was discussed. The
    description of D was proposed according to the mass action law. The results show that the D
    in non-polar diluents, kerosene and CCl4, is larger than that in polar diluent, 1-octanol
    and chloroform. The sodium sulfate in aqueous phase affects D strongly due to exchange of
    sulfate ions with Aliquat 336. Finally, the removal of 4,4′-diaminostilbene-2,2′-
    disulfonic acid (DSD acid), an amino sulfonic acid, was successfully achieved from
    wastewater by the extraction with Aliquat 336.
    Bubble Formation Characteristics from a Sieve Tray with Liquid Cross-flow
    QIN Wei, XU Shimin
    2002, 10(4):  416-419.  doi:
    Abstract ( )   PDF (1085KB) ( )  
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    An apparatus, designed to simulate bubbling of a sieve tray operated in froth regime, was
    employed.Bubble contact angles in and above the incipient weeping regime for an air-water-
    plexiglas system were investigated.The influence of both liquid cross-flow and gas up-flow
    upon bubble contact angles was examined. A model considering the influence of liquid cross
    -flow was developed to predict bubble size from a sieve hole in froth operation regime.The
    comparison shows that the bubble sizes predicted by the present model are consistent with
    our experimental values and the available published experimental data.
    Isolation of Soil Bacteria Species for Degrading Dibenzothiophene
    JIANG Chengying, LIU Huizhou, XIE Yuchun, CHEN Jiayong
    2002, 10(4):  420-426.  doi:
    Abstract ( )   PDF (1997KB) ( )  
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    Five bacterial strains, which are able to grow and to disintegrate dibenzothiophene (DBT)
    and dibenzothiophene sulfone (DBTO2) in fossil fuels, are isolated. Analysis of products of
    DBT metabolized by these strains shows that different bacteria strains oxidize DBT by
    different pathways. The isolated strains R-6, R-16, R-9 and R-8 can metabolize DBT to DBTO2
    and 2-hydroxybiphenyl (HBP), which are identified as Bacillus brevis, Bacillus sphaericus,
    Nocardia globerula and Pseudomonas delafieldii respectively. Another strain R-12 identified
    as Pseudomonas sp. can degrade DBT completely but it cannot produce DBTO2 and HBP. The
    optimum temperature and initial pH for desulfurization by R-8 are 32℃ and 7.02
    respectively and pH of the broth decreases during biodegradation. The growth of strain R-8
    with different sulfur-sources indicates that this strain in DBT medium has an induction
    period of 3 days, which is longer than those with dimethylsulfoxide and MgSO4 media, but
    the growth rate of the bacterial strain in DBT is higher after the induction. Higher growth
    and desulfurization rates are observed in the DBT-hexadecane system than in both DBT-
    ethanol and DBT-dimethylformamide systems. Both strains of R-8 and R-9 also show higher
    desulfurization activities toward other sulfur-substrates, indicating that they have
    greater desulfurization potential in application.
    Design Hybrid Methods for Encoding Prior Knowledge in Feedforward Network with Application
    in Chemical Engineering
    CHEN Chongwei, CHEN Dezhao
    2002, 10(4):  427-434.  doi:
    Abstract ( )   PDF (2637KB) ( )  
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    Three-layer feedforward networks have been widely used in modeling chemical engineering
    processes and prior-knowledge-based methods have been introduced to improve their
    performances. In this paper, we propose the methodology of designing better prior-
    knowledge-based hybrid methods by combining the existing ones. Then according to this
    methodology, two hybrid methods, interpolation-optimization (IO) method and
    interpolationpenalty-function (IPF) method, are designed as examples. Finally, both methods
    are applied to modeling two cases in chemical engineering to investigate their
    effectiveness. Simulation results show that the performances of the hybrid methods are
    better than those of their parents.
    Non-linear Chemical Process Modelling and Application in Epichlorhydrine Production Plant
    Using Wavelet Networks
    HUANG Dexian, JN Yihui, ZHANG Jie, A. J. Morris
    2002, 10(4):  435-443.  doi:
    Abstract ( )   PDF (2791KB) ( )  
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    A type of wavelet neural network, in which the scale function is adopted only, is proposed
    in this paper for non-linear dynamic process modelling. Its network size is decreased
    significantly and the weight coefficients can be estimated by a linear algorithm. The
    wavelet neural network holds some advantages superior to other types of neural networks.
    First, its network structure is easy to specify based on its theoretical analysis and
    intuition. Secondly,network training does not rely on stochastic gradient type techniques
    and avoids the problem of poor convergence or undesirable local minima. The excellent
    statistic properties of the weight parameter estimations can be proven here. Both
    theoretical analysis and simulation study show that the identification method is robust and
    reliable.Furthermore, a hybrid network structure incorporating first-principle knowledge
    and wavelet network is developed to solve a commonly existing problem in chemical
    production processes. Applications of the hybrid network to a practical production process
    demonstrates that model generalisation capability is significantly improved.
    UV-Catalytic Treatment of Municipal Solid-Waste Landfill Leachate with Hydrogen Peroxide
    and Ozone Oxidation
    Tahir Imran QURESHI, Hong-Tae KIM, Young-Ju KIM
    2002, 10(4):  444-449.  doi:
    Abstract ( )   PDF (2232KB) ( )  
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    The performance of UV/H2O2, UV/O3, and UV/H2O2/O3 oxidation systems for the treatment of
    municipal solid-waste landfill leachate was investigated. Main objective of the experiment
    was to remove total organic carbon (TOC), non-biodegradable organic compounds (NBDOC) and
    color. In UV/H2O2 oxidation experiment,with the increase of H2O2 dosage, removal
    efficiencies of TOC and color along with the ratio of biochemical oxygen demand (BOD) to
    chemical oxygen demand (COD) of the effluent were increased and a better performance was
    obtained than the system H2O2 alone. In UV/H2O2 oxidation, under the optimum condition H2O2
    (0.2 time),removal efficiencies of TOC and color were 78.9% and 95.5%, respectively, and
    BOD/COD ratio was significantly increased from 0.112 to 0.366. In UV/O3 oxidation, with the
    increase of O3 dosage, removal efficiencies of TOC and color along with BOD/COD ratio of
    the effluent were increased and a better performance was obtained than the system O3 alone.
    Under the optimum condition UV/O3 (50 mg.min-1), removal efficiencies of TOC and color were
    61.0% and 87.2%, respectively, and BOD/COD ratio was significantly increased from 0.112 to
    0.323. In UV/H2O2/O3 system, color removal and BOD/COD ratio were improved further and TOC
    removal efficiency was found to be 30.4% higher than the system UV/O3 without H2O2.
    Investigation on the morphology of adsorbed benzotriazole film on copper surface by
    scanning tunneling microcopy
    XU Chunchun, HE Zonghu, Wing yan NG
    2002, 10(4):  450-453.  doi:
    Abstract ( )   PDF (1077KB) ( )  
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    It is observed by scanning tunneling microscopy (STM) that the adsorbed Benzotriazole (BTA)
    on copper is long in shape and has an irregular rectangle. The growth of BTA on copper is
    in the form of polymeric chain and mainly in one dimension rather than two dimensions. The
    copper surface covered by BTA becomes flatter,smoother and the roughness was smaller than
    that of bare copper, so the corrosion is largely decreased. However,many grooves can be
    seen between BTA polymeric chains in which corrosion may exist to a degree.
    Excess Molar Volume and Apparent Molar Volume of Binary Mixtures of 2-Methyl-3-buten-2-ol
    with 1-Alcohol at 298.15K
    LIU Dixia, LI Haoran, DENG Dongshun, HAN Shijun
    2002, 10(4):  454-458.  doi:
    Abstract ( )   PDF (1448KB) ( )  
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    Excess molar volumes (VEm) of binary mixtures of 2-methyl-3-buten-2-ol [CH3C(OH)
    (CH3)CHCH2]with four 1-alcohols: methanol, ethanol, 1-propanol and 1-butanol at 298.15 K
    and atmospheric pressure are derived from density measurements with a vibrating-tube
    densimeter. All the excess volumes are negative in the systems over the entire composition
    range. The results are correlated with the Redlich-Kister equation. The effects of chain
    length of 1-alcohols on VmE are discussed. The apparent molar volumes of 2-methyl-3-buten-
    2-ol and 1-alcohols are calculated respectively.
    Influence of Energy on Solvent Diffusion in Polymer/Solvent Systems
    HU Huijun, JIANG Wenhua, AN Shijun
    2002, 10(4):  459-463.  doi:
    Abstract ( )   PDF (1401KB) ( )  
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    The Vrentas-Duda free-volume theory has been extensively used to correlate or predict the
    solvent diffusion coefficient of a polymer/solvent system. The energy term in the free
    volume diffusion equation is difficult to estimate, so the energy term was usually
    neglected in previous predictive versions of the free volume diffusion coefficient
    equation. Recent studies show that the energy effect is very important even above the glass
    transition temperature of the system. In this paper, a new evaluating method of the energy
    term is proposed, that is, the diffusion energy at different solvent concentrations is
    assumed to be a linear function of the solvent diffusion energy in pure solvents and that
    in polymers under the condition that the solvent in infinite dilution. By taking
    consideration of the influence of energy on the solvent diffusion, the prediction of
    solvent diffusion coefficient was preformed for three polymer/solvent systems over a wide
    range of concentrations and temperatures. The results show an improvement on the predictive
    capability of the free volume diffusion theory.
    Elemental Composition Method in Thermodynamics of Multireaction Systems (Ⅱ) Residual
    Properties,Property Changes of Mixing and Excess Properties Relations
    LIN Jinqing, LI Haoran, HAN Shijun
    2002, 10(4):  464-468.  doi:
    Abstract ( )   PDF (1100KB) ( )  
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    Based on the concept of "element" and the fundamental thermodynamic principle, the
    relationships of the residual properties, the property changes of mixing, excess
    properties, fugacity coefficients and activity coefficients between the hypothetical
    solution of elemental species and the equilibrated solution of actual species were
    established. The hypothetical solution of elemental species provides a way of reducing the
    dimensionality of problem, simplifying the analysis and visualizing the phase behavior.
    Measurements of the Critical Temperature and Pressure of Ethylene+Benzene+Et hylbenzene
    Mixture
    SUN Minghua, YE Ruqiang, LIU Tao, LIU Honglai
    2002, 10(4):  469-472.  doi:
    Abstract ( )   PDF (1336KB) ( )  
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    Critical temperature (Tc) and critical pressure (pc) of the ternary mixture of ethylene +
    benzene + ethylbenzene (the mole ratio of ethylbenzene to benzene was fixed at 0.95:0.05)
    were measured by using a highpressure view cell with direct visual observation. The
    interaction coefficients obtained from the critical properties of the relevant binary
    systems were used to predict the critical properties (Tc, pc) of the ternary mixture. The
    agreement between the prediction and experiments is satisfactory.
    RESEARCH NOTES
    Determination of the Critical Temperature and Critical Pressure of Five Compounds
    MA Peisheng, GAO Jin, XIA Shuqian
    2002, 10(4):  473-475.  doi:
    Abstract ( )   PDF (1021KB) ( )  
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    The critical properties of five compounds, including propanal, butanal, 1-pentanal, 2-
    methel butanal and trimer of ethanal, were determined for the first time by a new capillary
    quick-flow method. The apparatus was improved with a capillary tube and checked with hexane
    and 1-heptene as standard reagents. The experimental results proved that the determination
    of critical properties by quick-flow method with a capillary tube apparatus was successful.
    Mechanism of Off-Bottom Suspension of Solid Particles in a Mechanical Stirred Tank
    BAO Yuyun, HUANG Xiongbin, SHI Litian, WANG Yingchen
    2002, 10(4):  476-479.  doi:
    Abstract ( )   PDF (1323KB) ( )  
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    The minimum fluid velocity to maintain particles just suspended was deduced, and the
    theoretical analysis shows that the minimum velocity is influenced by the properties of the
    solid and liquid, not by the operational conditions. For justification, the local minimum
    velocity at the bottom of the tank was measured by a bi- electrode conductivity probe, in a
    square-sectioned stirred tank (0.75m×0.75m×1.0m) with the glass beads-water system.The
    experiments showed that the fluid velocities for the same suspension state were identical
    despite that the power dissipated per unit mass was not the same under different
    configuration and operation. Both theoretical analysis and experimental results indicate
    that the off-bottom suspension is controlled by the local fluid flow over the bottom of the
    stirred tank.
    Dependence of Reaction Rate Constants on Density in Supercritical Fluids
    WANG Tao, SHEN Zhongyao
    2002, 10(4):  480-482.  doi:
    Abstract ( )   PDF (644KB) ( )  
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    A new method, which correlates rate constants of chemical reactions and density or pressure
    in supercritical fluids, was developed. Based on the transition state theory and
    thermodynamic principles, the rate constant can be reasonably correlated with the density
    of the supercritical fluid, and a correlation equation was obtained.Coupled with the
    equation of state (EOS) of a supercritical solvent, the effect of pressure on reaction rate
    constant could be represented. Two typical systems were used to test this method. The
    result indicates that this method is suitable for dilute supercritical fluid solutions.
    Removal of β-Naphthalenesulfonic Acid from Aqueous Dilute Solution Using Bagasse Fly Ash
    LI Changhai, SHI Pengfei
    2002, 10(4):  483-485.  doi:
    Abstract ( )   PDF (1000KB) ( )  
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    Bagasse fly ash was converted into an inexpensive adsorbent and utilized for the removal of
    β-naphthalenesulfonic acid in dilute solution. The effect of pH, temperature, adsorbent
    concentration, and co-existed acids on the removal ofβ-naphthalenesulfonic acid was
    examined. The adsorption data have been correlated with both Langmuir and Freundlich
    adsorption models. Thermodynamic parameters obtained indicate the feasibility of the
    process, and kinetic studies provided the necessary mechanistic information of the removal
    process.
    Effect of Nitrogen Compounds on the Oxidation Stability of Saturate Fractions
    ZHOU Yasong, LIN Shixiong
    2002, 10(4):  486-489.  doi:
    Abstract ( )   PDF (1240KB) ( )  
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    A custom built dynamic oxygen uptake tester was used to study the influence of nitrogen
    compounds on the oxidation characteristics of the saturate fractions from mineral base
    oils. Experimental results indicate that nitrogen compounds, especially quinoline and
    indole, take part in the oxidation of saturates. It is also found that indole is more
    active than quinoline. The latter can be oxidized partly into ketoimine, and the former is
    more rapidly oxidized into acylamide. The oxidation products, ketoimine or acylamide, could
    inhibit the oxidation of the complex. For lower nitrogen content, the oxidation processes
    were accelerated. However, at higher nitrogen content,the oxidation induction periods were
    increased. The oxidation characteristics of saturates were also dependent on the type of
    catalysts presented.
    Lateral Solids Mixing in the Dense Zone of a Circulating Fluidized Bed
    YANG Hairui, LU Junfu, LIU Qing, YUE Guangxi
    2002, 10(4):  490-493.  doi:
    Abstract ( )   PDF (1195KB) ( )  
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    Lateral solid mixing was investigated experimentally in the dense zone of a 900mm×100mm×
    5.2m rectangular circulating fluidized bed riser. Using heated tracer injection, the
    lateral solid dispersion was determined by measuring the temperature response at different
    lateral positions. Furthermore, a one-dimensional dispersion model, which describes the
    solid mixing in the dense zone, is presented. The experimental results were used to
    determine the lateral particle dispersion coefficient under various operating conditions. A
    correlation of dispersion coefficient with bed height, gas velocity, and particle size is
    also proposed.