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Table of Content
05 August 2008, Volume 59 Issue 8
    Perspectives on chemical engineering in the 21st century
    LI Jinghai
    2008, 59(8):  1879-1883. 
    Abstract ( 936 )   PDF (629KB) ( 824 )  
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    Based on recent strategic studies of the Chinese chemical engineering community and analysis on the requirements from developing society and economy in China and the frontiers of science & technology in the world, this paper emphasized the opportunities and the challenges for chemical engineering science. As a common engineering science, chemical engineering must extend its applications to cope with the changing economy and society while upgrading its knowledge base. It is believed that the emergence of the complexity science, the progress in computer technology and computational science and the upgrade of experimental capability have generated new driving forces for chemical engineering science to open a new paradigm. Simultaneously, the changes in society and economy, the challenges in energy, resources and environment and the progresses in many high-tech fields have significantly extended the applicable domain for chemical engineering. The chemical engineering community must follow the tide of transdisciplinarity and convergency for science and technology to adapt the changing world and to contribute to the coming new era of chemical engineering.
    System theory in biotechnology industry development
    HUANG Xing, LI Yin, YANG Guang, ZHANG Yanping, CAO Zhu’an
    2008, 59(8):  1884-1893. 
    Abstract ( 667 )   PDF (3000KB) ( 440 )  
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    The characteristics of the biotechnology industry was analyzed by the system theory.In combination with recent breakthroughs in biotechnology industry, the successful cases were illustrated with emphasis on the application of the system theory.Compared with petrochemical industry, the importance of using the system theory in biochemical industry was highlighted.The progresses and problems were summarized in expectation of the more practical suggestions for the future.Perspectives of biotechnology industry were presented.

    Review of V2O5-supported carbon based catalyst for SO2 and NO removal from flue gas
    LIU Qingya, LIU Zhenyu
    2008, 59(8):  1894-1906. 
    Abstract ( 729 )   PDF (3299KB) ( 450 )  
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    Flue gas clean-up is an important task for sustainable development of China.Dominant technologies used today in the world are effective only for single pollutant removal under conditions significantly different from that of flue gas emission,and the overall cost for multi-pollutants removal is high.Carbon materials have superior properties for removal of many flue gas pollutants,individually or collectively,at temperatures of flue gas emission.V2O5/activated coke shows even higher activities mainly due to the oxidative properties of V2O5,which makes it better than activated coke itself and other metal oxides-modified activated coke.V2O5/activated coke may be the core for development of new generation technologies for flue gas clean-up.This article summarizes main research and development of V2O5/activated coke in the past decade,and reveals significant contributions made by Chinese researchers.

    综述与专论
    Relationship between micro-structure and properties of titania
    WEI Mingjie;SHAO Qing;LV Linghong;ZHU Yudan;LIU Weijia;LU Xiaohua
    2008, 59(8):  1907-1913. 
    Abstract ( 637 )   PDF (472KB) ( 427 )  
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    Titania is a new advanced metal oxide with favorable thermal and chemical stability,and is widely used in many fields such as photocatalyst,photoelectrical material,catalyst support,filler in composites.However,there are many difficulties in the applications of titania,while experiments could not explain the molecular interaction mechanism of these difficulties.Molecular simulation may give researchers an insight into the influence of micro-structure on apparent properties.This paper presents a brief review of the computer simulation investigation of the relationship between micro-structure and properties of titania,including wettability,catalysis reactivity and effect of confinement.

    CFD modeling of heat transfer in fixed bed reactors

    GUO Xueyan
    2008, 59(8):  1914-1922. 
    Abstract ( 858 )   PDF (1551KB) ( 440 )  
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    Fixed bed reactors(FBRs)have been widely used in chemical and bio-chemical processes.However,local flow and heat transfer in fixed bed reactors have challenged researchers for a long period.Although the effective parameter methods have been applied extensively to modeling local heat transfer in fixed beds,the general validity of effective parameters modeling is still questionable due to the lack of full understanding of local temperature fields in fixed beds.The computational fluid dynamics(CFD)technique is a new alternative to experimental approaches to investigate flows and heat transfer in fixed beds.It numerically solves the flow and/or transport governing equations and obtains local information like flow and temperature fields.In contrast to the averaged values acquired with the conventional theoretical and experimental methods,the results of CFD simulation are accurate local distributions of velocity,pressure,temperature,specie concentration and so on.The latest work and progress in the field of CFD modeling of heat transfer in fixed bed reactors were reviewed and analyzed,and also the perspectives of CFD application in fixed bed modeling were discussed.

    Three dimensional simulation for steady annular condensation in rectangular microchannels
    CHEN Yongping, WU Jiafeng, SHI Mingheng, ZHANG Chengbin, XIAO Chunmei
    2008, 59(8):  1923-1929. 
    Abstract ( 546 )   PDF (2842KB) ( 425 )  
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    A three dimensional model in rectangular microchannels with constant heat flux was developed to predict the steady annular condensation.The momentum and mass conservation equations both in the vapor and meniscus regions and the film thickness equation in the thin film region were numerically solved.The distribution of the meniscus curvature radius,thickness of the thin liquid film,heat transfer coefficient and wall temperature were obtained.The film thickness in the thin film region increased in the head stream to a maximum,and then decreased in the downstream.The average heat transfer coefficient in the thin film region was much larger than that in the meniscus.The highest heat transfer coefficient in a cross section appeared at the joint of the thin film region and meniscus,where wall temperature was the highest.The circumferential average heat transfer coefficient decreased drastically at the head stream to a lowest value.After that,the circumferential average heat transfer coefficient remained almost constant while approaching the end of the annular flow,then it decreased again.

    Characteristics of evaporating thin film interline region of extended meniscus in capillary microstructure
    ZHAO Na, DU Xiaoze, YANG Lijun, YANG Yongping
    2008, 59(8):  1930-1935. 
    Abstract ( 825 )   PDF (853KB) ( 572 )  
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    The surface evaporation of the extended meniscus liquid film in the microchannel driven by capillary force is the key process in heat sink and thermal management equipment.The physico-mathematical model was established by considering the variation of the apparent contact angle to describe the configuration of the total extended thin film region,including the equilibrium region,the interline region and the meniscus region.In addition,the ratio of disjoining pressure and capillary pressure was introduced to distinguish the film ranges of the different regions by considering the influence of film configuration,liquid property and channel size.The results indicated that the range of the interline region was quite small in the total extended meniscus region,nevertheless the variation of its surface temperature was much obvious,implying that the resulted Marangoni effect could cause great “pump” force to drive the film flow,which may be the main contribution of the interline region to the total extended thin film evaporation.The variation of evaporating rate,and also the resulted mean velocity of liquid film in the thin film interline region were revealed,which showed that there existed a local maximum value of evaporating rate in this region by the coupled influences of decreased film thickness and adhesion force caused by the disjoining pressure.

    Visualization experiments on air side heat transfer and fluid flow characteristics of arc-type and X-type slotted fin surfaces
    LI Hongzhi, LUO Yushan, WANG Haijun, CHEN Tingkuan, XIONG Wei, LI Chenfei
    2008, 59(8):  1936-1941. 
    Abstract ( 971 )   PDF (2600KB) ( 241 )  
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    Air side heat transfer and fluid flow characteristics of four-row slotted fin surfaces with arc-type and X-type strip arrangement in pressurized air cooler were studied by visualization experiments.Experiments were carried out with PIV(particle image velocimetry)system and infrared thermo tracer to visualize the flow field and the temperature distribution of two slotted fin surfaces.The experiment results showed that the fluctuation intensity and pressure drop of the X-type slotted fin surface were higher than those of the arc-type slotted fin surface.However,the heat transfer performance and field synergy property of the X-type slotted fin surface were superior to those of the arc-type fin surface.A new definition of fluctuation intensity was proposed to indicate the magnitude of flow disturbance enforced by the configuration and arrangement of slotted fin surface.The higher the fluctuation intensity,the larger the velocity gradient and the vorticity magnitude.The visualization experiment results provide a reliable experimental support for later numerical simulation and optimization design for new fin structures.

    传递现象

    Pertraction mass transfer process of phenol from aqueous solution using composite silicone rubber membrane

    XIAO Min;ZHOU Jiti;WANG Yinggang;WANG Li

    2008, 59(8):  1942-1949. 
    Abstract ( 519 )   PDF (1613KB) ( 338 )  
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    A pertraction system was constructed by flat sheet composite membrane [poly(dimethylsiloxane)(PDMS)/polyvinylidene fluoride(PVDF)].Phenol was chosen as model compound to study and caustic stripping solution(sodium hydroxide)was used as stripping solution.The mass transfer process and characteristics of the systems were investigated.The experiments were carried out to investigate the effects of composition and flow rate(feed and stripping solution),temperature,and thickness of selective layer on the pertraction mass transfer performance.The experimental results showed that the overall mass transfer coefficient(OMTC),Kov was independent of stripping solution flux and concentration(pH>13).Feed-side boundary layer mass transfer coefficient was proportional to Re0.46,and mass flux increased exponentially with increasing temperature,that is,Arrhenius relationship.OMTC was independent of initial phenol concentration(5.0—15.0 g•L-1).Membrane diffusive mass transfer coefficients of selective layer(thickness 4,6 and 8 μm)were 15.0×10-7,9.9×10-7 and 7.5×10-7 m•s-1 respectively(323.2 K),which were 2—4 times higher than those of homogeneous silicone rubber.Mass transfer resistance of phenol in membrane was also dominant for composite membrane system.

    Numerical simulation of immiscible two-phase flow in T-shaped microchannel
    DONG Hefei, ZHANG Deliang, ZHAO Yuchao, CHEN Guangwen, YUAN Quan
    2008, 59(8):  1950-1957. 
    Abstract ( 659 )   PDF (1096KB) ( 403 )  
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    The immiscible two-phase flow in a T-shaped microchannel was simulated by using the perturbational finite volume (PFV) method and level set technique.The effects of the oil-water interfacial tension and the surface wetting angle between water phase and microchannel wall on the characteristics of oil-water two-phase flow were investigated and the accurate interface configuration of the oil-water flow was also obtained.Some typical oil-water two-phase flow patterns in the T-shaped microchannel were calculated.The numerical results were in good agreement with the experimental data.The discussions of numerical results help to understand the flow mechanisms of oil-water two-phase flow in the microchannel.That provides a new means of numerical prediction for the experimental design and industrial application of liquid-liquid two-phase flow in the microchannel.

    多相流和计算流体力学

    CFD simulation of gas-liquid flow in bubble column

    LI Guang;YANG Xiaogang;DAI Gance

    2008, 59(8):  1958-1965. 
    Abstract ( 969 )   PDF (1615KB) ( 542 )  
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    Numerical simulations of gas-liquid flow in a cylindrical bubble column with two-fluid approach were conducted at superficial gas velocities varying from 0.02 m•s-1 to 0.30 m•s-1.A single scalar transport equation which described bubble size changes characterized by bubble interfacial areas was also incorporated into the simulations.In the models,the effect of bubble coalescence and break-up was taken into consideration.A modified k-ε turbulence model was used to describe liquid phase turbulence in the simulations,by accounting for the pseudo turbulence due to bubbles,while the gas phase turbulence viscosity was estimated based on the Tchen’s theory. The simulations only adopted the drag force for phase momentum exchange.The time averaged axial liquid velocities,gas hold up and gas phase interfacial areas obtained from the simulations were compared with the available experimental results.It was demonstrated from the simulations that the modeling in this work can reasonably predict the gas-liquid flow in the bubble column.

    PIV measurement of turbulent bubbly mixing layer
    GUO Fude, CHEN Bin, ZHANG Ximin, NING Tao, GUO Liejin
    2008, 59(8):  1966-1970. 
    Abstract ( 765 )   PDF (1332KB) ( 439 )  
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    Based on the particle imaging velocimetry(PIV)measurement of single-phase mixing layer flow,the gas-liquid two-phase bubbly mixing layer with the velocity ratio 4∶1 was experimentally investigated with PIV.The Reynolds number based on the velocity difference of two streams and hydraulic diameter of the channel ranged from 4400 to 158400.It was found that the bubbles injection could enhance the instantaneous velocity fluctuation when Reynolds number was small,but it would depress the instantaneous velocity fluctuation when Reynolds number was large.Afterwards the distributions of statistical Reynolds stress were obtained.Reynolds stress existed only in a very narrow region downstream of the mixing layer and increased with increasing Reynolds number.The distribution of Reynolds stress on the downstream cross-section showed that mean Reynolds stress value would decrease with bubble injection and there would be fluctuations on the same cross-section compared with the single-phase case.

    多相流和计算流体力学

    Flow behavior of binary mixture particles in gas-solid fluidized beds

    LIU Weiwei;LU Chunxi; FAN Yiping;SHI Xiaomeng;XU Chunming

    2008, 59(8):  1971-1978. 
    Abstract ( 600 )   PDF (1682KB) ( 386 )  
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    The axial average concentration and entrainment of binary mixture particles in freeboard were measured in a φ500 mm×12500 mm large scale cold model perspex experimental equipment, and according to the axial average concentration in freeboard the transport disengaging height (TDH) of binary particle could be obtained.It was indicated that TDH of binary mixture particles increased with increasing superficial velocity and mass fraction of fine particles.The increase of TDH with increasing mass fraction of fine particles was the least when mass fraction of fine particles was near 0.4.Entrainment of binary mixture particles in freeboard increased with increasing superficial velocity.When superficial velocity was less than 0.6 m•s-1, the increase of entrainment was prominent; moreover, when superficial velocity was more than 0.6 m•s-1, the trend of the increase of entrainment of binary particle was weak.When superficial velocity was less than 0.5 m•s-1, the increase of entrainment of binary particle with increasing mass fraction of fine particles was not obvious; when superficial velocity was more than 0.5 m•s-1, entrainment of binary particle increased with increasing mass fraction of fine particles.According to the analysis of experimental data, a mathematical model of TDH of binary particle was established.Calculated values were in good agreement with experimental values.

    Numerical simulation of shell-side flow in hollow fiber membrane modules
    YANG Yi, WANG Baoguo, PENG Yong
    2008, 59(8):  1979-1985. 
    Abstract ( 693 )   PDF (2116KB) ( 504 )  
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    Random sequential addition (RSA) algorithm was utilized to develop geometric models for hollow fiber membrane modules.The models, featuring radial and axial structure complexity in modules’ shell-side, were further integrated into numerical simulations to study hydrodynamic behaviors within tricky physical boundaries.Comparisons among simulation results and experimental data, as well as the empirical correlation in literature showed that the simulations were capable of describing the performance of certain commercial modules at low Reynolds number, thus making it possible to replace correlations for performance predictions in membrane module design.On the other hand, radial flow induced by axial non-ideal distribution of fibers might offset channeling and dead zone effects, which were key factors deteriorating module performance.A good design of axial fiber alignment might serve as a potential method for module performance intensification.

    多相流和计算流体力学

    Measurement of critical suspension speed for solid particles in stirred vessel based on acoustic method

    REN Congjing;WANG Jingdai;YANG Yongrong;ZHANG Xiaohuan
    2008, 59(8):  1986-1991. 
    Abstract ( 730 )   PDF (504KB) ( 422 )  
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    A characteristic frequency band of acoustic emission (AE) signals, which represented the motion of solid particles in a stirred tank was obtained by using wavelet transform and Hurst analysis. Then it was observed that the energy fraction of AE signals at different frequencies changed regularly with increasing impeller speed in the stirred tank. A new method for determining the critical suspension speed was presented based on this regular behavior. When the AE energy fraction in the characteristic frequency band decreased rapidly and began to level off, the corresponding impeller speed was the critical suspension speed. This new method was verified by the water-glass bead system, which showed that the average absolute relative deviation (AARD) was about 3.51% as compared with visual observation. The average relative error between the results from acoustic experiment and Zweitering equation was 3.17%. It is concluded that multi-scale analysis of acoustic signals is feasible for determining the critical suspension speed and has the merit of being sensitive, non-intrusive and accurate.

    Comparison of kinetic behavior of non-catalytic/catalytic liquid-phase oxidation of cyclohexane
    LIU Changjun, TANG Shengwei, TAN Pinghua, LIU Yingying, LIANG Bin, MIN Enze
    2008, 59(8):  1992-1999. 
    Abstract ( 765 )   PDF (1205KB) ( 591 )  
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    The kinetic behavior of the liquid-phase oxidation of cyclohexane was investigated in a bubble column under 1.1 MPa at various temperatures, in which gases with O2 concentrations ranging from 5% to 99% were used as oxidants.By comparing the non-catalytic and catalytic oxidation of cyclohexane, the free radical mechanism of the oxidation was discussed in detail.Both the mechanism analysis and experimental data showed that the catalyzed liquid-phase oxidation of cyclohexane was a reaction of first-order with respect to both cyclohexane and oxygen.For the non-catalytic oxidation, an induction period was obvious.During the non-catalytic oxidation of cyclohexane by oxygen, the chain initiating reaction was the rate determining step.Beyond the induction period, the reaction was accelerated and exhibited auto-catalytic behavior due to the release of radicals through the decomposition of cyclohexyl hydroperoxide when its concentration accumulated to a certain degree.On the other hand, in catalytic oxidation the cyclohexyl hydroperoxide decomposed rather quickly, and then accelerated the reaction.And during the reaction, the concentration of cyclohexyl hydroperoxide kept very low and the chain propagation became the rate limiting step.

    Filtration and catalytic performance of blended TS-1/CNF composite catalyst
    ZHAO Qian, LI Ping, LI Daoquan, ZHANG Leiming, ZHOU Xinggui, YUAN Weikang, HU Xijun
    2008, 59(8):  2000-2006. 
    Abstract ( 698 )   PDF (1077KB) ( 147 )  
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    Carbon nanofiber (CNF) is a novel carbon based catalyst support.A TS-1/CNF composite catalyst was synthesized in liquid phase by using a method of mechanical blending.The filtration performance of the blended TS-1/CNF composite in aqueous system and its catalytic performance on ammoximation of cyclohexanone were studied.As compared with pristine TS-1 catalyst, the TS-1/CNF composite was comprised of relatively larger particles, which could be easily filtrated from the aqueous system.Meanwhile, there were a great number of macro pores in agglomerates of TS-1/CNF composite formed via CNF interweaving, in favor of liquid penetration through the filter layer of TS-1/CNF.The SEM images revealed that TS-1 particles were uniformly adsorbed on CNF surface.The unique long filament and large external surface of CNF might offer abundant adhesion sites to TS-1 particles. Strong inter-molecular, electrostatic and hydrophobic forces might exist between TS-1 particles and CNF, preventing the supported TS-1 from detaching off the CNF during stirring and filtering.The results of ammoximation of cyclohexanone over the blended TS-1/CNF composite catalyst showed that the conversion of cyclohexanone and the yield of oxime could reach 100% and 98.4%, respectively, as high as those obtained over pristine TS-1 catalyst.

    Apparent kinetics of in-situ hydrogenation of phenol in liquid phase over Raney Ni catalyst
    XIANG Yizhi, LU Chunshan, ZHANG Qunfeng, MA Lei, WU Xiaoqiong, LI Xiaonian
    2008, 59(8):  2007-2013. 
    Abstract ( 760 )   PDF (776KB) ( 266 )  
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    The effect of reaction conditions on the performance of in-situ hydrogenation of phenol in liquid phase over Raney Ni catalyst was studied.The results indicated that higher phenol conversion and cyclohexanol selectivity could be obtained under the condition of higher temperature and pressure, and lower space velocity and methanol content, while phenol concentration had almost no effect on the reaction performance.The study of apparent kinetics indicated that the reaction orders with respect to phenol and adsorbed hydrogen for cyclohexanol formation (α1 and β1) were 0.93 and 3.82, respectively, and those for cyclohexanone formation (α2 and β2) were 1.09 and 3.47, respectively.The apparent activation energy to cyclohexanol (Ea1) and cyclohexanone (Ea2) were 67.8 kJ•mol-1 and 80.2 kJ•mol-1, respectively.The role of reaction conditions on the in-situ hydrogenation performance of phenol (hydrogenation rate, selectivity of products) could be clarified on the basis of the apparent kinetics results.

    催化、动力学与反应器

    Benzene formation routes in VGO catalytic cracking

    GONG Jianhong;XU Youhao;XIE Chaogang; LONG Jun
    2008, 59(8):  2014-2020. 
    Abstract ( 871 )   PDF (433KB) ( 216 )  
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    Daqing vacuum gas oil(VGO) was catalytically cracked over catalysts of different zeolite types in a small FFB (fixed fluid bed) unit to study the aromatics shift and aromatics generation which are two important routes of benzene formation in the catalytic cracking process.With the Y zeolite the turning point from aromatics shift to aromatics generation happened at the conversion of about 30%.The respective contributions to benzene formation from aromatics shift and aromatics generation were about 36% and 64%, and the dealkylation of about 5% of alkylbenzene present in the feed was also helpful to form benzene.Accordingly with the ZSM-5 zeolite the turning point happened at the conversion of about 55%,the respective contributions were about 20% and 80%, and dealkylation of about 10% of alkylbenzene present in the feed was helpful to form benzene.The ratio of benzene to aromatics originating from aromatics generation was basically constant, not varying with conversion, but it was closely relevant to the type of zeolites.Some of the benzene formed by reactions was again consumed at the conversion of about 75% during Daqing VGO cracking.Reaction temperature had an important effect on the formation of benzene.

    Modelling and experimental validation of micromixing in rotating packed bed

    XIANG Yang;CHEN Jianfeng;GAO Zhengming

    2008, 59(8):  2021-2026. 
    Abstract ( 912 )   PDF (1198KB) ( 499 )  
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    Coupled with coalescence-redispersion model and lamella model, a new model was presented to describe the flow, mixing and reaction process in rotating packed bed (RPB) and calculate the mixing-dependent product selectivity.The model was solved numerically with boundary conditions of RPB characteristics.As operational variables were changed, the model predicted well the effect of variables on the product selectivity while considering macro-distribution non-uniformity of inlet liquid.The influence of volumetric ratio, rotating speed and flow rate on segregation index was investigated.The results showed that the process was controlled by reaction kinetics while operating at a small volumetric ratio, but the micromixing rate had remarkable effect on the reaction process at a high volumetric ratio.In the micromixing-controlled region, segregation index decreased with increasing rotating speed but the increase of flow rate had little effect on segregation index.

    Effect of process conditions of interfacial polymerization on performance of reverse osmosis composite membrane
    QIU Shi, WU Liguang, ZHANG Lin, CHEN Huanlin, GAO Congjie
    2008, 59(8):  2027-2034. 
    Abstract ( 1085 )   PDF (1563KB) ( 795 )  
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    Reverse osmosis composite membrane was prepared by interfacial polymerization (IP) of metaphenylene diamine (MPD) with trimesoyl chloride (TMC) on the surface of polysulfone (PS) support.The effects of monomers concentration, reaction time of IP, time and temperature of heat treatment on the separation performance of composite membranes were investigated.The influences of phase-transfer catalyst (PTC) on the separation performance of composite membrane were also studied, and the mechanism of reaction process was discussed.From the orthogonal experiment results, the optimum conditions were the concentration of TMC and PMD 3 g•L-1, 20 g•L-1 respectively, and the temperature and time of heat treatment 90 ℃ and 15 min, and the flux of 14.91 L•m-2•h-1 as well as rejection of 0.951 (pressure 1.6 MPa, temperature 25℃, concentration of NaCl 20000 mg•L-1) were obtained under these conditions.In addition, it was found that at a low concentration of MPD, the separation performance of composite membrane could be remarkably improved by adding PTC into the water phase.

    Specific component of acrylic series resin with inverse gas chromatography and its influence on adsorption capacity for oil fume
    LI Jing, LI Zhong, KANG Zhongxian, XI Hongxia, XIA Qibin
    2008, 59(8):  2035-2040. 
    Abstract ( 590 )   PDF (1204KB) ( 267 )  
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    The relationship of specific component of polymeric resins with surface polarity of polymeric resins on adsorption capacity of cooking oil were investigated.The specific components of polymeric resins PIBA, PMMA-BMA, PLMA-2-EHMA and G-1651 resin were measured with inverse gas chromatography(IGC).The results of IGC showed that specific components were negative, which meant that this adsorption was spontaneous.The specific components of four resins followed the order: G-1651 resinPIBA>PMMA-BMA>PLMA-2-EHMA.The order of adsorption capacity for oil fume was PLMA-2-EHMA > PMMA-BMA > PIBA >G-1651 resin, which was contrary to the polarity of resins.The polarity of a polymeric resin showed a strong influence on the adsorption capacity for cooking oil.Because most components of oil fume were non-polar or weakly polar, the higher the specific component, the stronger the adsorption capacity of resin for oil fume.

    Sub-microweighing technique for measurement of partitioning of drugs between supercritical fluid and impregnated polymer
    MA Shaoling, LU Zhaowen, BI Erli, WU Youting, ZHANG Zhibing, MENG Weimin
    2008, 59(8):  2041-2045. 
    Abstract ( 608 )   PDF (688KB) ( 170 )  
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    A high-pressure quartz crystal microbalance (QCM) apparatus was developed to investigate the absorption of carbon dioxide in two glassy polymer films—polystyrene (PS) and polyvinylpyrrolidone (PVP) at 40℃ and pressure up to 9.0 MPa.PVP was shown to have better CO2 absorption and chosen as the representative for supercritical impregnation of two model drugs—o-aminobenzoic acid and ibuprofen at 40℃ and pressure up to 8.0 MPa.It was found that the two impregnants were embedded into the polymer with a partition coefficient as high as 104 order of magnitude.Since the sub-microweighing technique established and utilized in this study was simple, convenient and accurate, it was believed that the technique could have wide and effective applications in supercritical impregnation processes.

    过程系统工程

    Optimization of regeneration recycling water networks with internal water mains

    FENG Xiao;SHEN Renjie;YU Xinjiang

    2008, 59(8):  2046-2051. 
    Abstract ( 713 )   PDF (825KB) ( 323 )  
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    A water network with regeneration recycling can reduce freshwater consumption and wastewater discharge to the maximum extent.Networks with internal water mains are normally more flexible, and more convenient to operate and control.In this paper, a general methodology for the design of optimal regeneration recycling water networks with internal water mains was proposed, based on a newly established superstructure.The optimization was virtually a multi-objective problem.Considering the relative importance of these objectives, sequential optimization was adopted.Freshwater consumption, regenerated water flowrate and contaminant regeneration load, were minimized in sequence, which corresponded to three mathematical models.By solving these models step by step, a regeneration recycling water network could be constructed, which was economically favorable.A case study showed the effectiveness of the method.

    Adaptive local learning based least squares support vector regression with application to online modeling for fermentation processes
    LIU Yi, WANG Haiqing, LI Ping
    2008, 59(8):  2052-2057. 
    Abstract ( 737 )   PDF (1034KB) ( 325 )  
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    A new online modeling method based on adaptive local learning and least squares support vector regression was proposed for nonlinear multi-input multi-output processes.Both distance measure and angle measure were used to evaluate the similarity between data, thus a more comprehensive and relevant set was constructed.In the present method, the model parameters were optimized online by using the fast leave-one-out criterion.In addition, an online adaptive model selection strategy for modeling of fermentation processes was developed.Simulations on a fed-batch streptokinase fermentation process showed that the active biomass and streptokinase concentrations could both be predicted simultaneously just from the second batch.The results also showed that the proposed method was more accurate and adaptive compared with the alternative modeling methods.

    过程系统工程

    Time delay estimation of soft-sensor model based on hybrid differential evolution algorithm

    WANG Junyan;HUANG Dexian
    2008, 59(8):  2058-2064. 
    Abstract ( 845 )   PDF (1237KB) ( 460 )  
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    Time delay estimation is one of the most important issues in system control and signal processing.Through establishing an appropriate fitness function, the time delay estimation of soft-sensor model could be formulated as a multi-dimension nonlinear functional optimization problem, which could be solved by hybrid differential evolution (HDE) algorithm.Numerical simulation results on two benchmarks demonstrated the effectiveness and robustness of HDE.Taking a crude atmospheric distillation unit in oil refinery as an example, a numerical application of the soft-sensor model for the kerosene flash point was made.The application results demonstrated that the accuracy of soft-sensor model was greatly improved with the introduction of time delay estimation.Besides, the effectiveness of the proposed HDE was confirmed.

    Maximized pyruvate production through temperature shifting strategy based on kinetics model
    XU Qinglong, LIU Liming, SHI Zhongping, DU Guocheng, CHEN Jian
    2008, 59(8):  2065-2070. 
    Abstract ( 712 )   PDF (1383KB) ( 225 )  
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    In the batch fermentation of pyruvate, temperature is one of the most important environmental factors that affect pyruvate productivity.The effect of temperature, varying from 26℃ to 34℃, on production of pyruvate in a 7 L stirred fermenter by T.glabrata CCTCC M202019 was investigated.A modified Logistic equation and Luedeking-Piret equation were used to estimate kinetics of cell growth and pyruvate production.The effect of temperature on the estimated kinetic parameters was further studied by regression analysis.Based on kinetic parameters analysis, a temperature-shifting strategy was proposed, in which, at 0—8 h, culturing was performed at 34℃ to obtain a high specific cell growth rate, and at 8—42 h, the temperature was decreased step by step from 34℃ to 27℃ to keep a high pyruvate production rate.After 42 h, the temperature was maintained at 27℃ to weaken inhibition of pyruvate and offer constant production capacity of pyruvate in the anaphase of fermentation.A high concentration (89.4 g•L-1), yield (0.76 g•g-1) and productivity (1.32 g•L-1•h-1) of pyruvate were achieved by applying this strategy, which were 25.7%, 16.9% and 48.3% higher than batch fermentation at a constant temperature 30℃, respectively.

    Isolation of phoC from Enterobacter aerogenes and its characteristics on enzymatic phosphorylation of inosine by fusing PhoC with MBP
    ZHAO Hongxin, LAI Qiheng, YANG Cheng, ZHANG Zineng, XING Xinhui
    2008, 59(8):  2071-2078. 
    Abstract ( 647 )   PDF (1688KB) ( 254 )  
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    Acid phosphotransferase of E.aerogenes IAM1183 is of high potential for industrial application due to high regiospecificity of the nucleoside phosphorylating activity to the C-5′-position.In this study, the phoC gene was isolated and sequenced from E.aerogenes IAM1183 and fused with the MBP (maltose binding protein) gene to construct expressing vector pMKL-c2x-phoC named as pcphoC.The pcphoC was transferred into different host strains for the expression of the MBP-Pho fusion protein.It was found that the transformed E.coli TB1I (pcphoC) exhibited the highest phosphotransferase activity.The hydrolysis activity was lower than that of the original strain.And the optimum pH was 6.7 in the vicinity of neutral.

    Reaction-diffusion kinetics for enzymatic hydrolysis of konjac glucomannan
    YUAN Suxia, SU Rongxin, QI Wei, LI Qiujin, HE Zhimin
    2008, 59(8):  2079-2082. 
    Abstract ( 897 )   PDF (872KB) ( 273 )  
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    Enzymatic hydrolysis of konjac glucomannan(KGM)by β-mannanase was studied at constant mass ratio of enzyme to substrate to investigate the reaction-diffusion mechanism.By using size exclusion chromatography(SEC),the changes in molecular weight distribution of KGM were followed during the process of hydrolysis.When the ratio of enzyme to substrate was constant,the changes in molecular weight at different KGM concentrations were remarkably different,which showed that the reaction depended on the diffusion of enzyme.The changes in molecular weight showed a zero-order kinetics.Integrating the empirical reaction kinetics and diffusion characteristics,a reaction-diffusion model was established from a series of chromatographic results.But the degradation rate was shown to be greatly affected by the diffusion of enzyme as well as the concentration of substrate.This equation of reaction kinetics indicated the importance of diffusion,and the experimental data can be well predicted at semi dilute concentrations of KGM.

    Emission characteristics of thermal processing of tannery sludge in paddle dryer
    ZHU Xiaowan, DENG Wenyi, WANG Fei, JIANG Xuguang, YAN Jianhua, CHI Yong, CEN Kefa
    2008, 59(8):  2083-2088. 
    Abstract ( 793 )   PDF (1828KB) ( 266 )  
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    Thermal drying experiments of tannery sludge were conducted in a sludge paddle dryer.The drying characteristics of sludge, emission characteristics of flue gases and condensed water quality were analyzed.The result indicated that three kinds of volatile compounds, i.e., ammonia, volatile fatty acid (CHCOOH, CH3CH2COOH) and alkane (heptane) were found in the thermal drying process.The water content of sludge decreased by increasing the temperature of heat-transfer oil.The concentration of volatile compounds and the COD value of condensed water were also influenced by the hydrolysis and decarboxylation in this process.The concentration of volatile compounds was measured before and after condensation.It was found that condensation could markedly reduce the emission of gaseous pollutants.

    能源和环境工程

    Characteristics of liquid droplet motion at gas diffusion layer/gas flow channel interface in PEM fuel cells

    XIAO Yu; MING Pingwen;YI Baolian

    2008, 59(8):  2089-2094. 
    Abstract ( 742 )   PDF (1491KB) ( 233 )  
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    Two dimensional models based on the typical part in the flow field of PEM fuel cell were presented to analyse the characteristics of liquid droplet motion at the gas diffusion layer(GDL)/gas flow channel(GFC)interface.There were some regular relationships among the contact angle hysteresis(the difference angle between the advancing and the receding angle of moving droplet),the height of the droplet and the velocity of the shear flow,however,the length of the typical part chosen by random had no effect on the result.This model also coupled the condition when the droplets just ran-off from the surface,and reflected the trend of droplet moving,chasing and coalescing.Analysis showed that:lower flow passage,higher fluid velocity and adopting hydrophobic GDL interface to increase the instability of droplets,while using hydrophilic GFC interface to get bigger acceleration were all good ways for removing water from the fuel cell by corner flow.

    Theoretical study on pyrolysis mechanism of O-containing model compound anisole in coal
    ZHAO Lijuan, LING Lixia, ZHANG Riguang, LIU Xuefang, WANG Baojun
    2008, 59(8):  2095-2102. 
    Abstract ( 952 )   PDF (1923KB) ( 497 )  
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    The isomeric pyrolysis mechanism of anisole was investigated using the density functional theory(DFT) of quantum chemistry.Two parallel consecutive reaction paths were determined, which involved the formation of intermediate o- and p-methyl cyclohexadienone followed by H transfer.The theoretical evidence of this important intermediate was proposed.The mechanism resulted in the formation of the two major products, o- and p-cresol.The yields of major products were almost the same, which was in accordance with the experimental fact.Kinetic analysis showed that the homolysis of O—CH3 bond in anisole was the rate-determining step, and the activation energy was 285.90 kJ•mol-1 at 1000 K.

    Experimental study on coal gasification in interconnected fluidized bed
    WU Jiahua, SHEN Laihong, XIAO Jun, LU Haiyong, WANG Lei
    2008, 59(8):  2103-2110. 
    Abstract ( 796 )   PDF (773KB) ( 226 )  
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    Gasification of coal in a novel interconnected fluidized bed was proposed in this paper.The novel fluidized bed resembled a high velocity circulating fluidized bed in combination with a bubbling fluidized bed after a cyclone.The circulating fluidized bed was designed for coal combustion fed with air, the bubbling fluidized bed was for coal gasification fed with steam.The heat required for gasification was supplied by means of the circulation of inert heat carrier particles.Direct contact between the gasification and combustion processes was avoided.The experiments of coal gasification were performed in a laboratory apparatus of interconnected fluidized bed, and high quality syngas was produced free of N2 dilution.The effects of gasifier temperature and steam/coal ratio on gas composition, heating value, cold gas efficiency and total carbon conversion were discussed.The experimental results indicated that with the increase of gasifier temperature and steam/coal ratio, both heating value and cold gas efficiency increased rapidly.Total carbon conversion increased remarkably with the gasifier temperature at the lower temperature range of 900—950℃, and reached its maximum of 92% at the gasifier temperature of 950℃, and then kept nearly constant.The steam/coal ratio had little effect on the variation of total carbon conversion in the process of coal gasification in the novel interconnected fluidized bed.The maximum heating value and cold gas efficiency could reach 6.9 MJ•m-3 and 68%, respectively.

    Kinetics and mechanism of chloronitrobenzenes wastewater ozonation
    LI Bingzhi, XU Xiangyang, ZHU Liang
    2008, 59(8):  2111-2120. 
    Abstract ( 682 )   PDF (743KB) ( 410 )  
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    The kinetics and mechanism of ozonation degradation of chloronitrobenzenes (ClNBs) in aqueous solution were investigated in a semi-continuous reactor, and the molecular and free radical contribution of ozone to the degradation of ClNBs was also evaluated.The results of kinetic studies showed that the decomposition of ClNBs was a pseudo-first-order reaction with respect to pollutant concentration and the degradation rate was in the order o-CNB<m-CNB<p-CNB.The overall rate constant increased with increasing pH, however decreased with increasing pollutant and free radical scavenger concentration.Furthermore, the TOC removal rate was significantly lower than the degradation rate.Ozonation could not reduce TOC completely, the results of HPLC and GC-MS showed that p-CNB was mainly transformed into p-chlorophenol, p-nitrophenol, 2-chloro-5-nitrophenol, etc., and carboxylic acids with low molecular weight.Finally, it was found through evaluating the contribution of ozone molecule and hydroxyl radical that hydroxyl radical played a decisive role in the removal of ClNBs.Therefore, advanced oxidation processes(AOPs) which enhance the generation of free radicals in eliminating this kind of pollutants from environment may be a preferred choice.

    能源和环境工程

    Analytical calculation of leakage rate for natural gas pipelines

    LIU Zhongliang;LUO Zhiyun;WANG Jieteng;ZHANG Jian;SUN Xiaochun

    2008, 59(8):  2121-2126. 
    Abstract ( 932 )   PDF (799KB) ( 892 )  
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    As the leakage rate is one of the important factors of natural gas pipeline operation that have not been well defined,it is necessary and important to give an analytical equation for the leakage flow rate of natural gas pipelines to improve the accuracy of simulation and estimation of leakage accidents.Based on the theories of thermodynamics and fluid mechanics,together with the use of ideal gas equation of state,adiabatic equation and energy conservation equation,the natural gas leakage process was studied and divided into two leakage phases,the critical phase and the sub-critical phase.Equations were obtained for calculating the leakage flow rate of the whole leakage process,and examples were given to analyze the influences of various parameters on leakage flow rate.

    Structural characteristics of sodium lignosulfonates and its use as dispersant of dimethomorph water-dispersible granules
    LI Zhili, PANG Yuxia, LI Xiaona, QIU Xueqing
    2008, 59(8):  2127-2133. 
    Abstract ( 893 )   PDF (1112KB) ( 601 )  
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    Structural characteristics of different sodium lignosulfonates (SLs),Kinsperse126,Ultrazine Na,Borresperse Na, GZMN, and SXMN were investigated with ultraviolet spectrum, gel chromatography and chemical titration.The total hydrophilic groups content of Ultrazine Na was 5.46 mmol&#8226;g-1, which was the highest among these SLs.The sulfonic groups content of Kinsperse126 was 2.05 mmol&#8226;g-1, which was the highest among these SLs.The weight-mean relative molecular weight (Mw) of GZMN was 13000, which was the largest of these SLs.Mw of SXMN was 10000.Each SL was used as dispersant of dimethomorph water-dispersible granules (WG) respectively.The properties of dimethomorph WG were also investigated.The suspending rate of the WG with Kinsperse126 was as high as 95.03%.The suspending rate of the WG with SXMN was 89.70%.The dispersion ability of SL increased with increasing content of sulfonic groups and increasing Mw.Moreover, the sulfonic groups content was more important than Mw.Turbiscan LabExpert was initially used to estimate the stability of dimethomorph WG’s suspension.The suspension with Kinsperse126 had the best stability, in which deposition did not appear until 15 min and the height of sediment was only 0.38 mm.Particle size increase in the WG’s suspension with GZMN was only 0.59 μm which was the lowest.The stability depended on the dispersion ability of SL; furthermore, a larger Mw could weaken particle size increase.

    材料化学工程与纳米技术

    Preparation and water absorbency performance of modified feather protein grafted acrylic acid-acrylamide superabsorbents

    YIN Guoqiang;CUI Yingde;CHEN Xunjun

    2008, 59(8):  2134-2140. 
    Abstract ( 1227 )   PDF (1199KB) ( 635 )  
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    Modified feather protein grafted poly(acrylic acid-acrylamide) superabsorbents [P(MFP-g-AA/AM)] were synthesized by using modified feather protein (MFP), acrylic acid (AA) and acrylamide (AM) as start materials, N,N′-methylenebisacrylamide (NMBA) as crosslinker and K2S2O8-NaHSO3 as initiator.The water absorbency performance and its influence factors of the P(MFP-g-AA/AM) superabsorbents were investigated.The results showed that the preferable synthesis conditions for P(MFP-g-AA/AM) were as follows: WAAWAM=70∶30, WMFPWAA+AM=10%, WcrosslinkerWAA+AM=0.10%, WinitiatorWAA+AM=0.8%, neutralization degree of the acrylic acid 90%, reaction temperature 60℃ and reaction time 2 h.The absorbency of the P(MFP-g-AA/AM) superabsorbents was 578.0 g&#8226;g-1 in the case of de-ionized water,78.6 g&#8226;g-1 in the case of 0.9% NaCl solution and 75.1 g&#8226;g-1 in the case of artificial urine, higher than the absorbency of modified feather protein grafted acrylic acid superabsorbents.

    Microwave assisted recycle of waste PET and preparation of polyester used in powder coating
    SONG Hongwei, XU Zhongbin, ZHENG Suxia
    2008, 59(8):  2141-2148. 
    Abstract ( 862 )   PDF (1947KB) ( 219 )  
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    The waste poly(ethylene terephthalate) (PET) could be glycolized with neopentyl glycol (NPG) in several minutes with microwave assistance.The glycolized product, an oligomer, was esterified with a certain amount of hexanedioic acid and 1,2,4,5-benzene-tetracarboxylic acid dianhydride.The esterified products could be used as the polyester for polyester-epoxy powder coatings.The influences of the main factors, such as the amount of NPG, the power of microwave, reaction time, on the glycolysis and esterification were studied and optimized.The effects of 1,2,4,5-benzenetetracarboxylic acid dianhydride introduced during the esterification process were also investigated.

    Batch-semi-batch two-stage RAFT mini-emulsion polymerization of styrene
    YANG Lei, LUO Yingwu, LI Bogeng
    2008, 59(8):  2149-2155. 
    Abstract ( 837 )   PDF (2402KB) ( 214 )  
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    A batch-semi-batch two-stage reversible addition-fragmentation chain transfer(RAFT) mini-emulsion polymerization of styrene was investigated.It was found that the starting point of the feeding stage (the semi-batch stage) and the solid content of the final latex were critical to reducing the amount of coagulum.The monomer feeding of the second stage should start after monomer conversion 40% of the first stage and the solid content of the final latex should remain below 40%.Under such conditions little coagulum was observed.It was concluded that the two-stage semi-batch RAFT mini-emulsion polymerization was effective to synthesize higher molecular weight polymer (~8×104 g&#8226;mol-1) with narrow molecular weight distribution (PDI=~1.3) and low residues of the surfactant and co-stabilizer (~1.5%,mass).