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Table of Content
05 August 2009, Volume 60 Issue 8
    Measurement and correlation of VLE data for α-pinene + limonene and p-cymene + limonene systems under atmospheric pressure
    TONG Zhangfa, YANG Zhengyu, LIAO Dankui, WEI Tengyou, CHEN Xiaopeng
    2009, 60(8):  1877-1882. 
    Abstract ( 717 )   PDF (692KB) ( 411 )  
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    Vapor-liquid equilibrium (VLE) data for binary systems of α-pinene(1)+(S)-(-)-limonene(2) and p-cymene(1)+(S)-(-)-limonene(2) were determined under 100.7 kPa by using the modified Ellis equilibrium still.Parameters of four solution models, Liebermann-Fried, Wilson, NRTL and UNIQUAC, were calculated with the least squares method and an objective function based on the pressure.Comparisons of the VLE predictions from the four solution models above were made with the result from the UNIFAC model.The Liebermann-Fried model used to correlate the isothermal VLE data and excess molar enthalpies was found to be more accurate than the others, in predicting isobaric VLE data.

    Application of molecular simulation in density characterization and structure validation of heavy oil fractions
    REN Wenpo, CHEN Honggang, YANG Chaohe, SHAN Honghong
    2009, 60(8):  1883-1888. 
    Abstract ( 751 )   PDF (938KB) ( 533 )  
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    Average molecular structure of heavy oil fractions was constructed by elemental analysis, molecular weight determination, NMR.And then, the rationality of density and molecular structure was justified with molecular simulation.At first, n-tetracontane and 1-dodecyl naphthalene were selected as model compounds to do density simulation, which was used to establish the simulation parameters and calculation process.Under the same simulation condition, the density of heavy oil fractions was simulated, and then compared with the experimental value.The result showed that the relative errors of density of n-tetracontane and 1-dodecyl naphthalene were 0.27% and 0.26% respectively, indicating that the simulated condition was suitable for density characterization.The density values of heavy oil fractions obtained by molecular simulation compared well with the experimental value, and the relative errors were between 2% and 3%.The consistence of simulation density and experimental density confirmed that the average molecular structure of heavy oil fractions were deduced reasonably.Therefore, molecular simulation could be used as a tool to estimate of density, and the result could justify the average molecular structure of heavy oil fractions.

    热力学

    Performance estimation method and formula for low-temperature multi-effect evaporation seawater desalination system

    WANG Yongqing
    2009, 60(8):  1889-1893. 
    Abstract ( 941 )   PDF (794KB) ( 566 )  
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    Low temperature multi-effect evaporation (LT-MEE) seawater desalination systems with top brine temperature lower than 70℃ have attracted attention in recent years.A method for performance estimation of LT-MEE is proposed, and a formula is built for a typical LT-MEE configuration.Excluding complex properties of working fluids and details of heat and mass transfer processes, this formula involves only simple algebraic operations, thus provides a convenient way to evaluate the water production of LT-MEE for different motive heat source conditions and design parameters.Comparing the formula prediction with the data from both rigorous models and references, it indicates that the formula can give good results in wide parameter ranges.Although this method is proposed based on a typical LT-MEE configuration, it is also applicable to other LT-MEE configurations and thermal desalination systems.

    Microscale boiling and microbubble dynamics under pulse heating
    CHEN Gang, QUAN Xiaojun, CHENG Ping
    2009, 60(8):  1894-1899. 
    Abstract ( 641 )   PDF (1754KB) ( 199 )  
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    Using microelectromechanical system(MEMS)technology,a Pt microheater fabricated on a glass wafer was placed in a silicon-based microchannel of trapezoidal cross section.With the aid of a high-speed charge coupled device(CCD)camera and based on Pt’s linear temperature-resistance characteristics,flow boiling phenomena and temperature response on the surface of the microheater in the microchannel under pulse heating were observed and recorded.At a given mass flux,two types of microscale boiling were observed with increasing imposed voltage,especially the growth of stable vapor film which rarely appeared in other similar researches.Finally,the corresponding microbubble dynamics and the differences during two neighbor pulse durations due to non-condensed gas were analyzed.

    PIV experimental study and field synergy analysis of external flow field of vibrating tube
    JIANG Bo, TIAN Maocheng, QIU Yan, TANG Yufeng, CHENG Lin
    2009, 60(8):  1900-1905. 
    Abstract ( 791 )   PDF (3345KB) ( 333 )  
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    Using particle image velocimeter(PIV)combined with CFD dynamic mesh,an experimental and simulation study was carried out on flow field in the near-wall region outside a vibrating tube.The charts of velocity vector of flow field outside the tube under five conditions with amplitude 1.3 mm and frequency 5—25 Hz were obtained,and the cosine of average synergy angle of flow field outside the tube was calculated.Experimental and simulation results showed that vibration could significantly increase flow velocity in the near-wall region outside the tube,and cause effective scouring on both sides of tube wall in the vibration direction.The average velocity of near-wall region outside the tube showed an approximate linear increase with the increase of vibrating frequency,and reached a peak when resonance condition appeared.In the same region,the cosine of average synergy angle under vibrating condition was greater than that under non-vibrating condition,but there occurred a narrower change of cosine of average synergy angle at different vibrating frequencies.Besides,preliminary measures were proposed to improve heat transfer of vibration surface by analysis of field synergy.

    Flow and heat transfer characteristics in silicon-based microchannels with internal ribs
    LIU Enguang, WU Huiying, TANG Huimin
    2009, 60(8):  1906-1911. 
    Abstract ( 642 )   PDF (1198KB) ( 258 )  
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    At present, channels made of copper, aluminum or stainless steel are widely used for the heat transfer enhancement research, but the fabrication precision and size of these traditional channels are usually limited.In this paper, silicon-based microchannels with square internal ribs were made by the MEMS method, and their flow and heat transfer characteristics were experimentally investigated for the first time.It was shown that the flow and heat transfer characteristics were affected apparently by rib height and the distance between two neighboring ribs.When compared with the smooth silicon microchannels without internal ribs, both the friction factors and Nusselt numbers of the silicon microchannels with internal ribs increased, and the heat transfer enhancement performance of the silicon-based microchannels with internal ribs was mainly dependant on rib height and rib distance.The entrance effect on the flow and heat transfer in the silicon microchannels was obvious.

    Heat transfer performance of inclined spray cooling in non-boiling regime
    WANG Yaqing, LIU Minghou, LIU Dong, XU Kan
    2009, 60(8):  1912-1919. 
    Abstract ( 828 )   PDF (2481KB) ( 360 )  
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    Experiments were conducted to study the effect of inclination angle(the angle between the normal of surface and the axis of symmetry of the spray)on heat transfer of spray cooling in the non-boiling regime by using water as coolant.A generalized correlation was developed for local and average Nusselt numbers as a function of the spray Reynolds number and non-dimensional temperature when the mass flow rate ranged from 4.44—7.05 L•h-1.The spray was produced by using a semi-solid swirl nozzle under the atomization pressure of 0.5 MPa.The results showed that at a fixed inclination angle,the optimum orifice-to-surface distance where the heat transfer performance was the best was determined when the major axis of the elliptical spray impact area intersected the square test surface.Comparing different inclination angles from 0° to 49° at the optimum orifice-to-surface distance,the heat transfer performance and cooling efficiency increased with increasing inclination angle.

    传递现象

    Molecular dynamics simulation of diffusion coefficients of small molecules in amorphous PET

    WANG Pingli;WANG Zhiwei;HU Changying;CHEN Mo

    2009, 60(8):  1920-1925. 
    Abstract ( 979 )   PDF (1031KB) ( 463 )  
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    Diffusion of molecules with molecular weights ranging from 32 to 339 in amorphous polyethylene terephthalate(PET) was examined by using molecular dynamics simulation.The diffusion coefficients were calculated based on Einstein relation and the influence of simulation time and density on diffusion coefficients was discussed.The results showed that for a higher temperature a shorter simulation time was needed in order that the linear area in mean square displacement (MSD) curves could be observed while for a lower temperature a longer simulation time was needed.Diffusion coefficients decreased with increasing density of the polymer and a higher density required a longer simulation time.Comparison of the calculated diffusion coefficients with experimental values found in the literature indicated that the calculated and experimental values were in the same order of magnitude.It suggested that the polymer model was acceptable and could describe correctly the diffusion process of small molecules in PET.This work can provide an approximate method of calculating diffusion coefficient, which is the key parameter in the migration model.

    3D numerical simulation of fluid flow and heat transfer enhancement in plastic elliptic oblique teeth flat strip tube
    SHU Junjie, LI Qunsong, YU Tianlan, LIU Yuejin, PENG Deqi
    2009, 60(8):  1926-1931. 
    Abstract ( 640 )   PDF (2101KB) ( 241 )  
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    With the help of Fluent 6.2 and supporting softwares,computer 3D numerical simulation of fluid flow and heat transfer enhancement of plastic elliptical oblique teeth flat strip tubes with eddy port were performed,and the flow rate,turbulence intensity and improvement of convective heat transfer coefficient distribution in smooth tubes and plastic elliptic oblique teeth flat strip tubes were analyzed and compared.The results showed that the fluid flow in flat strip tubes was complicated three-dimensional flow,mainly swirling flow.With interference flow by flat strip,flow rate and turbulence intensity increased greatly.Fouling deposition around inner wall was effectively inhibited and heat transfer was enhanced.Compared with smooth tubes,average heat transfer coefficient inside flat strip tubes increased by 45%.The pressure drop caused by oblique teeth flat strip was in the permissible range of engineering application.It was suitable for the heat exchanger at a flow rate lower than 0.8 m•s-1.

    Experiment and analysis of visualization and heat transfer of MPP condensers
    TONG Mingwei, YE Liang, ZENG Xin, YANG Jiankang, ZHU Yunqi
    2009, 60(8):  1932-1937. 
    Abstract ( 1025 )   PDF (1715KB) ( 544 )  
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    Based on the heat transfer analysis of two-phase zone augmentation technique employed in multiple parallel-pass (MPP) condenser, visualization and performance tests are employed to compare and evaluate the performance of MPP condenser by referencing a same-sized parallel flow(PF) condenser as a baseline sample.Visual observation by using a high-speed camera indicates that a more uniform refrigerant quality entering the next cooling pass can be achieved in MPP condenser because superheat vapor through a pass-through hole on flow distributor directly injects into a liquid -vapor zone in a header tube.In addition, analytical and test results show MPP condenser, being designed to enlarge two-phase condensing zone, is able to improve cooling performance as high as 9.6% while its refrigerant mass flow increases as high as 13.34% when comparing with a benchmark PF condenser.

    Effect of temperature on formation of crystalline fouling on heat exchanger surface
    ZHAO Liang, ZOU Yong, LIU Yida, LIU Wen, CHENG Lin
    2009, 60(8):  1938-1943. 
    Abstract ( 718 )   PDF (1140KB) ( 309 )  
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    The effect of temperature on the crystalline structure and morphology of calcium carbonate fouling was investigated by X-ray diffraction analysis and SEM observation.The experimental results indicated that temperature not only affected the crystalline type of fouling, but also affected the lattice parameter and particle size of the precipitated phase.Calcite was the main precipitated phase at a lower temperature, and the amount of aragonite would increase with increasing temperature.The disturbance induced by low temperature boiling could reduce the size of aggregating fouling particle.

    传递现象

    Local characteristics in converging-diverging tube with delaying self-sustaining swirl flow

    HONG Mengna;DENG Xianhe
    2009, 60(8):  1944-1949. 
    Abstract ( 777 )   PDF (1278KB) ( 313 )  
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    The distributions of thermal resistance in viscous sublayer,buffer region and turbulent core region,local flow resistance and local heat transfer characteristics at different locations downstream of the twisted-tape element were numerically studied in a converging-diverging tube inserted with spaced twisted-tape element by analyzing the attenuation of self-sustaining swirl flow.The results showed that the local performance was poor as thermal resistance was too concentrated in its distribution for a particular region.The more uniform the distribution of thermal resistance,the better the local performance.The local performance reached its best when the fluid just left the spaced twisted-tape,in which the flow resistance dropped substantially but the enhancement of heat transfer was still significant.The self-sustaining flow was maintained at a long distance.The best performance was at the length of 36.85 times the diameter,increasing by 6.8% compared with a converging-diverging tube.

    多相流和计算流体力学

    Application of DSMC method in large-scale gas-solid two-phase impinging streams

    DU Min;HAO Yingli;LIU Xiangdong

    2009, 60(8):  1950-1958. 
    Abstract ( 1096 )   PDF (3816KB) ( 390 )  
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    The direct simulation Monte Carlo(DSMC)method based on Lagrangian approach was applied to large-scale gas-solid two-phase impinging streams with a large number of particles to solve the problem of calculating too many particle collisions with the particle trajectory model.A mathematical model for the gas-solid two-phase impinging streams was proposed.The gas flow field,particle distributions and collision positions were analyzed based on the calculation results.The particle motion behavior,particle residence time and the particle effect on gas flow by considering the particle collision were compared with those without considering the particle collision.The results indicated that the DSMC method can be effectively applied to the numerical study of large-scale gas-solid two-phase impinging streams.The particle distribution can be divided into three zones:particle-collision zone,particle-jetting zone and particle-scattering zone.Particle collisions occurred mainly in the particle-collision zone causing enrichment of particles and decreased residence time of particles in the area.The particle effect on gas flow was not significant at a small particle to gas ratio of the present study.

    Flow characteristics in micro/mini cylinder group

    ZHAO Xiaobao;LIU Zhigang;ZHANG Chengwu

    2009, 60(8):  1959-1964. 
    Abstract ( 874 )   PDF (1118KB) ( 252 )  
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    De-ionized water, used as working fluid, flowed through micro/mini cylinder group plates with 3.5 mm width and 40 mm length, which were made up of micro/mini cylinder group with diameter of 0.5 mm and heights of 1.0 mm, 0.75 mm, 0.5 mm and 0.25 mm, respectively.The flow rate and pressure drop between inlet and outlet of micro/mini cylinder group plates were measured and the resistance characteristics of micro/mini plates at staggered array and at in-line array could be experimentally studied.The investigation showed that the value of fRe was approximately constant in micro/mini cylinder group plates when flow was purely laminar state.The values of fRe for all test sections except test sections with 0.25 mm cylinder height would increase with the increase of Re at Re>100, as a result of eddy resistance, enhancement of stream pulse and acceleration of stream frequency.For test sections with 0.25 mm cylinder height, the values of fRe increased quickly and oscillatingly when Re was larger than 150 due to the influence of the micro-size effect and the roughness effect on the cylinder surface and bottom of micro/mini cylinder group plates.The friction factor at staggered array was much larger than that at in-line array for micro/mini cylinder group plates, and the higher the cylinder height, the lower the friction factor.

    Multi-scale and multi-fractal characteristics of tube-pressure signals in Kenics static mixer
    WU Jianhua, MENG Huibo, YU Yanfang, GONG Bin
    2009, 60(8):  1965-1973. 
    Abstract ( 771 )   PDF (1477KB) ( 331 )  
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    In order to understand the intrinsic mechanism of heterogeneity, non-linearity and chaotic behavior of fluid system in Kenics static mixer (KSM), the signals of tube-pressure fluctuation dynamics with different flow rates were collected with a high speed collector.Tube-pressure signals at different flow rates denoised by using the wavelet transform modulus maxima method were firstly decomposed to 1-7 scale detail signals and scale approximation and then evaluated by using multi-scale and R/S analysis method based on Daubechies second order wavelet.By analyzing the profiles of different scale signals, different fractal structures at different scales were found, and the similar trend of fractal structures with increasing flow rate was established.Besides, there were some non-periodic components in the system, and the similar energy exchange between particles caused the diffusion of turbulence, which was characteristic of an open system.The vortex with different scales would cause the chaos.The energy profiles of different scale signals indicated that pressure fluctuations mainly reflected the macro-scale interaction between vortex and liquid phase.

    Effect of number of mixing elements on flow field in Kenics static mixer
    GONG Bin, BAO Zhongping, ZHANG Chunmei, WU Jianhua
    2009, 60(8):  1974-1980. 
    Abstract ( 996 )   PDF (1908KB) ( 401 )  
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    In order to evaluate the influence of number of mixing elements on velocity distribution and turbulence,the flow field inside a Kenics static mixer(KSM) was measured by using laser Doppler velocimetry.The results showed that the velocity in the KSM was redistributed and the turbulence was strengthened due to the mixing elements.It took place primarily in the first three elements,in which the turbulence was strengthened but the rate of increase fell off along the mixing elements.And more important,the strengthening effect was most significant for the first element and the stabilized state was reached after the fourth element.When the number of the mixing elements was more than three,the limit of strengthening fluid turbulence was reached and the turbulence was no more strengthened by increasing the number of mixing elements.

    催化、动力学与反应器

    Milliseconds steam reforming of methane using Rh/MgO/γ-Al2O3 catalyst

    YANG Yiyang;DING Shi;JIN Yong;CHENG Yi
    2009, 60(8):  1981-1987. 
    Abstract ( 632 )   PDF (1130KB) ( 361 )  
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    Steam reforming of methane(SRM)on Rh/MgO/γ-Al2O3 catalyst with contact time of milliseconds for producing hydrogen was studied.The effects of reactor temperature,space velocity and rhodium loading were investigated in detail at the H2O/CH4 molar ratio of 1 or 3.The results showed that Rh/MgO/γ-Al2O3 catalyst was extremely active and stable during the process of methane steam reforming.Under the conditions of rhodium loading of 5%(mass),H2O/CH4 molar ratio of 3,reaction temperature at 1150 K and space velocity at 641.11 L•(g cat)-1•h-1,methane conversion could reach 90% and the selectivity to carbon dioxide was about 20%.The reaction performance approached nearly thermodynamic equilibrium within milliseconds contact time.A high reaction temperature benefited the progress of the reaction.

    Gas phase in-situ hydrogenation of methyl benzoate to benzaldehyde
    ZHOU Yinjuan, PAN Guoxiang, XIANG Yizhi, LU Chunshan, ZHANG Qunfeng, MA Lei, LI Xiaonian
    2009, 60(8):  1988-1996. 
    Abstract ( 1019 )   PDF (663KB) ( 476 )  
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    An in-situ hydrogenation process of methyl benzoate (MB) to benzaldehyde in gas phase was proposed.A Cu-MnO/γ-Al2O3 bi-functional catalyst was prepared with the impregnation method, and was used for the proposed process.The effects of catalyst composition, reaction temperature, feeding rate, and molar ratio of methyl benzoate/methanol/water in the feed on the conversion of methyl benzoate and the selectivity of benzaldehyde were investigated with a fixed-bed reactor under atmospheric pressure.Under the optimal conditions (molar ratio of MB/methanol/water,temperature and feeding rate were 0.5/40/40,420℃,0.1 ml•min-1), the selectivity of benzaldehyde reached 88.5%, and the conversion of MB was 79.6%.In addition, the Cu-MnO/γ-Al2O3 catalyst was quite stable for such a reaction.Moreover, a reaction mechanism was proposed based on the product distribution of the in-situ hydrogenation of methyl benzoate to benzaldehyde.In this process, external supply of hydrogen was not needed, which is different from the traditional hydrogenation process in gas phase.

    Agglomeration and demulsification of emulsions by ultrasound
    ZHOU You, SUN Liyun, ZHENG Guoqiang, LV Xiaoping
    2009, 60(8):  1997-2002. 
    Abstract ( 694 )   PDF (2356KB) ( 703 )  
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    A stable emulsion was prepared by using dichloroethane as the dispersed phase and water as the continuous phase.Agglomeration and demulsification of the emulsion in ultrasonic standing wave field were studied.The factors affecting demulsification, such as ultrasound intensity, treating time, sedimentation time, ultrasonic frequency, were investigated.The results showed that the change of ultrasound directly affected the cohesion and dispersion of the particles, and ultrasound intensity should be lower than a critical value.The treating time also should be lower than a critical value.The equation for calculating the best ultrasonic frequency was proposed, and the experimental results verified the calculated best ultrasonic frequency.The orthogonal experiment was designed by considering energy consumption and demulsification efficiency.The optimum experimental conditions of the demulsification were ultrasonic frequency of 10 kHz,sound intensity of 270 W• m-2,irradiation time of 9 min,sedimentation temperature of 40℃ and sedimentation time of 3 h.Under the optimum experimental conditions, the demulsification efficiency could reach 91%.

    Application of distributed parallel algorithm for long term crude oil scheduling
    ZOU Laixi, LI Chufu, HE Xiaorong
    2009, 60(8):  2003-2009. 
    Abstract ( 610 )   PDF (1599KB) ( 316 )  
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    A novel distributed parallel algorithm for crude oil scheduling is presented in order to shorten the long computation time in the scheduling of a long scheduling horizon problem.The event-tree based modeling and optimization algorithms are adopted and the whole problem is divided into two sub problems (the portside sub problem and the refinery sub problem).Thus, the algorithm is proposed by analyzing the solving sequence of the two sub problems.The algorithm is based on master-slave distributed model.The master node solves the refinery sub problem firstly and sends the quality changeover sequence that is needed to start the portside scheduling to slave nodes, then the slave nodes send the results back to the master node.By comprehensive comparison of the results of the two sub problems, an optimized scheduling scheme will be obtained.The numerical example demonstrates that the algorithm is efficient in reducing the time overhead, especially when the crude oil distillation units(CDUs) have different feed quality requirements and the scheduling horizon is very long.For example when the horizon is 4 weeks, the sequential algorithm can not get a feasible solution in 48 h while the proposed algorithm can get optimal solution within 25 h.

    过程系统工程

    Fault isolation:an FDA-SVDD based pattern classification algorithm

    ZHU Zhibo;SONG Zhihuan

    2009, 60(8):  2010-2016. 
    Abstract ( 750 )   PDF (2151KB) ( 256 )  
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    In order to overcome the shortage of fault isolation in multivariable statistical process control, a new fault isolation algorithm was proposed that included Fisher discriminant analysis (FDA) based feature extraction, Fisher linear classification and support vector data description (SVDD) based pattern classification in nonlinear kernel space.FDA-SVDD based cascade and series parallel combination forms were constructed, and a novel SVDD based weighted normalization radius discriminance was designed.The simulation of a non-isothermal continuous stirred tank reactor (CSTR) process showed that the series parallel combination form had better fault isolation performance than the simple FDA method and the cascade combination form.

    A novel iterative learning control for product quality control in batch process

    JIA Li;SHI Jiping;CHIU Minsen
    2009, 60(8):  2017-2023. 
    Abstract ( 668 )   PDF (1443KB) ( 507 )  
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    Considering that it is difficult to analyze the convergence of iterative learning optimal control for quality control of batch processes, a novel iterative learning control based on data-driven neural fuzzy model for product quality control in batch process was proposed.In the presented algorithm, the region of the searching space for optimal solution is changed by adding a new constraint condition, which resulted in the convergence of the product quality in batch axes.Moreover, the rigorous proof was given.Lastly, to verify the efficiency of the proposed algorithm, it was applied to a benchmark batch process.The simulation results showed that the proposed method was better and could be applied to practical processes, thus it provides a new way for the control of batch processes.

    Dissipative particle dynamics simulation of SBA-15 mesophase formation
    CHEN Huiyong, WU Yongbiao, ZHOU Bihong, XI Hongxia, XIA Qibin, LI Zhong, QIAN Yu
    2009, 60(8):  2024-2030. 
    Abstract ( 923 )   PDF (2569KB) ( 1129 )  
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    Dissipative particle dynamics (DPD) method is performed to investigate the surfactant-silica cooperative organization effects in the mesoporous silica SBA-15 formation process, and steady shear is introduced to represent stirring in actual experiment.Simulation results show that uniform spherical super-molecular micelles can be assembled by the cooperation of the two precursors in SBA-15 formation, the template copolymer (P123) and the silica source (TEOS).The hydrophobic PPO micelle cores play a decisive role in the uniform mesopore formation process of SBA-15, while the hydrophilic PEO micelle coronas interact with the silica matrix to form the micropores upon calcinations.When steady shear introduced into the simulation system, the P123/TEOS super-molecular assembly no longer form spherical micelles, but form cylindrical micelles with hexagonally array, and finally form the structure of SBA-15.The simulation results proved that the DPD method can exactly describe the surfactant-silica cooperative organization and the SBA-15 mesophase formation process, which is also an effective tool for investigating the formation mechanism of ordered mesoporous silica.

    De-flocculating behavior of flocculating yeast SPSC01 under chemostat conditions
    LIU Chenguang, LI Ning, Xumeng, BAI Fengwu
    2009, 60(8):  2031-2039. 
    Abstract ( 778 )   PDF (1499KB) ( 580 )  
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    The de-flocculating of the flocculating yeast SPSC01 under chemostat conditions was monitored with the focused beam reflectance measurement system (FBRM).When the medium containing 50 g•L-1 glucose, supplemented with 4 g•L-1 yeast extract and 3 g•L-1 peptone was fed at the dilution rate of 0.12 h-1, the size of the yeast flocs started to decrease in 15 days, indicating the occurrence of de-flocculating of the culture system.Batch culture and fermentation demonstrated that the free yeast cells de-flocculated from the yeast flocs grew faster but less tolerant to ethanol inhibition, making the chemostat culture system more favorable for them to grow and overtake the yeast flocs with extension of the culture period.A dynamic model was developed to simulate this de-flocculating process and the impact of de-flocculating probability, dilution rate, growth kinetic parameters, and a bioreactor operation model was further analyzed.It was expected that the improvement of the retention of the yeast flocs within the bioreactor could effectively prevent the de-flocculating from occurring, which was validated by installing a baffle within the bioreactor to retain the yeast flocs.

    Biosynthesis of glycyrrhetinic acid monoglucuronide by whole-cell of Penicillium purpurogenum in an aqueous / organic system
    ZOU Shuping, ZHANG Qi, LI Limin, GUO Yanxia, DAI Dazhang, LI Chun
    2009, 60(8):  2040-2045. 
    Abstract ( 850 )   PDF (7004KB) ( 306 )  
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    Biosynthesis of glycyrrhetinic acid monoglucuronide (GAMG) by β-D-glucuronidase from the whole cell of Penicillium purpurogenum Li-3 in an aqueous / organic system was studied.Results showed that tert-butyl alcohol is the best organic solvent and the optimum volume ratio of aqueous to organic phase is 3 to 7.The rest optimum conditions for this biocatalysis are 1.5 g•L-1 of substrate concentration, 45℃ of temperature, pH 5.0, 7 g•L-1 of enzyme concentration and 120 r•min-1 of shaking rate.Under these optimized conditions,79.12% yield of GAMG was achieved after 48 h reaction. The whole-cell enzyme has a good reusability and a high stability, which demonstrates the prospect for real application.

    Splitting reaction of corn stalk powder in discharged plasma
    SONG Chunlian, ZHANG Zhitao, CHEN Wenyan, YANG Xianli, LAN Shaowei
    2009, 60(8):  2046-2053. 
    Abstract ( 739 )   PDF (2721KB) ( 326 )  
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    Corn stalk powder was processed in high pressure non-equilibrium plasma aiming to produce saccharide compounds by one step without oxidation and combustion.The results show that corn stalk powder can be splitted into saccharide compounds, such as monosaccharide and disaccharide etc., in discharged plasma without any pretreatment and any additives.The optimized splitting conditions were found to be: 70℃ of circumstance temperature, 90 kPa of pressure, 0.35 L•min-1 of media gas N2 flow, 0.1 L•min-1 of saturated vapour flow, 3 kV of discharge voltage, 0.60 mm of discharge gap, and 60 min of discharge duration. Under these conditions, the conversion of corn stalk powder was 69.36% with the selectivity of 39.68%, and the yield of saccharide compounds was 40.16%.These results clearly illustrated that the production of saccharide compounds by the splitting of corn stalk powder is possible without any acid or alkali or any other complicated pretreatment, and the process can proceed even with no needs of high temperature and high pressure.

    Hydrogen production from reform of bio-oil aqueous phase over Z204 catalyst using two-stage fixed bed reactor
    WANG Lu, WANG Tiejun, ZHANG Qi, XU Ying, CHANG Jie
    2009, 60(8):  2054-2060. 
    Abstract ( 1019 )   PDF (1376KB) ( 464 )  
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    Influence of commercial catalyst Z204 on steam reforming performance of bio-oil aqueous fraction for hydrogen production was studied using two-stage fixed bed reactor.Effects of reaction and distillation temperatures on hydrogen production, as well as the lifetime of the catalyst and the characteristics of the distillation residue were investigated.Comparative study illustrated that the yield of hydrogen production with Z204 catalyst was much higher than that without Z204 catalyst,with the highest hydrogen yield of 47%.Under the conditions of reaction temperature of 750 ℃ and distillation temperature of 200℃, the hydrogen yield kept about 35% within 4 h of reaction.

    Mechanism of mercury speciation transformation based on combined removal at medium-to-low temperature
    WANG Xihe, GAO Jihui, WANG Shuai, YANG Jianguo, DU Qian, WU Shaohua
    2009, 60(8):  2061-2066. 
    Abstract ( 751 )   PDF (1172KB) ( 276 )  
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    Combined removal with other coal fired pollutants was an effective method to control mercury emission during coal combustion.Accelerating the transformation of Hg0 to Hg2+ could enhance the performance of air pollution control devices in mercury emission control.Therefore, it is necessary to understand the influence factors of mercury speciation transformation.A bench scale test rig was built to simulate the process of mercury oxidation by gas components by using the Ontario Hydro Method for mercury detection at medium-to-low temperature.It was found that 90% Hg0 could be oxidized by Cl2 at the concentration of 10 μl•L-1.The process of Hg0 oxidation was sensitive within a range of SO2 concentration, out of which SO2 concentration had little influence on Hg0 oxidation.HCl, as the reaction product of H2O and Cl2, could also oxidize mercury from Hg0 to Hg2+, but its oxidation ability was weaker than Cl2, which generally made H2O an inhibitor of Hg0 oxidation.The process of NO2 decomposition would release free oxygen atoms which could oxidize mercury from Hg0 to Hg2+, so mercury oxidation by NO2 should be considered in a comprehensive kinetics model.

    Screening aerobic strains from AAC reactor and comparative study on properties of strains combination
    WEN Shumei, LI Chun, FU Weichao, LU Jianjiang, CAO Peng
    2009, 60(8):  2067-2073. 
    Abstract ( 622 )   PDF (2540KB) ( 299 )  
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    According to the characters of aerobic-anaerobic coupled reactor (AAC) with effective treatment of wastewater and achievement of sludge reduction in tomato catsup processing, aerobic strains were isolated from the aerobic field of AAC, and 29 bacterial strains were obtained.The performances of these strains to tomato processing wastewater treatment were investigated by compatibility test.Six bacterial strains were determined as the dominant ones by TOC removal rate in 12 hours.A fundamental flora including 2 strains was constructed by comparing TOC removal rate, in which the TOC removal rate and the ratio of cell growth increment to TOC removal were 85.29% and 1.89, respectively.On this basis, an efficient flora including 7 strains was constructed by comparing the TOC removal rate, the ratio of cell growth increment to TOC removal and the settling ability.The ratio of cell growth increment to TOC removal of this efficient flora decreased to 0.94, and the ratio of sludge production to TOC removal was reduced by 50.26%.With this efficient flora, the sludge settling property improved obviously and the OD600 decreased to 0.347, and the effluent water quality met the second grade criteria of integrated wastewater discharge standard in China.

    Application of acylated weak base resin for treatment of highly chromium-containing wastewater
    CAO Feiting, LIU Xiaoning, LI Xiang, WEI Rongqing, LIU Tao, CHEN Xiao, ZHANG Limin, XIA Mingfang
    2009, 60(8):  2074-2079. 
    Abstract ( 1005 )   PDF (882KB) ( 360 )  
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    Acylated weak base resin was used to the treatment of highly chromium-containing wastewater.A set of technology about resin adsorption and gradient desorption was established.The ion-exchange ability of the acylated weak base resin could be improved obviously by acid pickling.The application of gradient desorption made the concentration of chromium enriched for 6 times.With these techniques, the treated wastewater could meet the regulation for draining, and also the waste chromium resource could be recovered.IR and elemental analysis of the fresh and recovered resin samples indicated that the resin structure and efficiency are stable.

    Chemical looping combustion of sawdust in a 10 kWth interconnected fluidized bed
    WU Jiahua, SHEN Laihong, XIAO Jun, WANG Lei, HAO Jiangang
    2009, 60(8):  2080-2088. 
    Abstract ( 965 )   PDF (2025KB) ( 292 )  
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    A 10 kWth interconnected fluidized bed reactor (air reactor and fuel reactor) for chemical looping combustion was designed and built.The experiments on chemical looping combustion of biomass (sawdust) with NiO/Al2O3 oxygen carrier were performed in this reactor.The effects of fuel reactor temperature and steam/biomass ratio (S/B) on the gas composition of both fuel reactor and air reactor, combustion efficiency, etc., were discussed.The results indicated that the fuel reactor temperature was an important factor which affected the process of chemical looping combustion.With the increase of fuel reactor temperature, CO2 content increased, and CH4 content decreased evidently.CO content increased remarkably with increasing fuel reactor temperature in the temperature range 720—820℃, and reached its maximum at the temperature 820℃, and then decreased remarkably after the fuel reactor temperature exceeded 820℃.A higher fuel reactor temperature would contribute to increasing combustion efficiency.With the increase of steam/biomass ratio, CO and CH4 content increased, CO2 content and combustion efficiency decreased accordingly. In a total continuous operation time of 100 h, the oxygen carrier which was prepared by using impregnation exhibited extremely good oxidation-reduction reactivity and strong recycling ability.It was an ideal oxygen carrier for chemical looping combustion of biomass.

    Effect of heating-rate on Ca-based absorbent performance of CO2 capture
    LUO Jian, ZHUO Yuqun, FENG Wujun, CHEN Changhe, XU Xuchang
    2009, 60(8):  2089-2094. 
    Abstract ( 720 )   PDF (1444KB) ( 833 )  
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    A wire-mesh reactor capable of heating samples at a given heating-rate (1—1000 K•s-1) was used to investigate the effect of heating-rate on Ca-based absorbent performance of CO2 capture.BET method was used to analyze the morphology of the produced CaO, and the capabilities of the absorbent were compared.It was found that CaO calcined at a higher heating-rate had more appropriate pore distribution for CO2 capture, and the capability of CaO calcined at 1000 K•s-1 was 15% higher than that calcined at 1 K•s-1 determined by TGA.

    Preparation of novel polyampholyte water treatment agent
    QI Zheng, QI Peishi, YANG Wei
    2009, 60(8):  2095-2100. 
    Abstract ( 759 )   PDF (504KB) ( 467 )  
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    Mg3Al layered double hydroxides (Mg3Al-LDHEPCL) was grafted through free radical polymerization using S2O2-8/S2O2-5 redox initiator.Monomers used for the graft copolymerization were composed of anionic monomers acrylic acid (AA) and sodium acrylate (SA) as well as cationic monomers trimethylallyl ammonium chloride (TMAAC) and dimethyldiallyl ammonium chloride (DMDAAC).The produced hybrid graft copolymer, Mg3Al-LDHEPCL-g-PAA-PSA-co-PTMAAC-co-PDMDAAC, can be used as polyampholyte sewage treatment agent.The graft copolymerization process was monitored by differential scanning calorimetry (DSC) to obtain the kinetic characteristics in the foamed dispersion polymerization system.The graft copolymerization composition was optimized aiming to achieve lower water content in the sludge and lower COD value in the filtrate.The optimized composition was found to be m(Mg3Al-LDHEPCL )∶m(AA+SA+TMAAC+DMDAAC)=0.12∶1;m(TMAAC+DMDAAC)∶m(AA+SA+TMAAC+DMDAAC)=0.288∶0.712, and the neutralization ratio of AA was 18%—24%.Hydrolysis analog studies in 1.0 mol•L-1 NaOH solution revealed that the layered cluster of Mg3Al-LDHEPCL hydrolyzed into multiple lamellar segments forming a secondary quaternary ammonium polyampholyte that functioned as coagulation agent.These inherent structural characteristics are important factors for improving the dehydration effect significantly.The crystal structures were characterized by XRD and IR.

    Synthesis and swelling properties of multiresponsive chitosan microgel
    LIU Weijun, HUANG Yongmin, PENG Changjun, LIU Honglai
    2009, 60(8):  2101-2106. 
    Abstract ( 911 )   PDF (608KB) ( 513 )  
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    Poly(N-isopropylacrylamide)/chitosan microgel was synthesized by surfactant-free emulsion polymerization.The morphology and stimuli-responsive properties of the microgel were characterized with transmission electron microscope and dynamic light scattering.The results showed that the microgel particles presented a microsphere with core-shell morphology.The addition of chitosan had a significant effect on the volume phase transition temperature (VPTT) of PNIPAM microgel, and the VPTT shifted to a high temperature with increasing amount of chitosan.This result was consistent with measurements of differential scanning calorimeter.The diameter changes of the microgels at various pH solutions indicated that the size decreased gradually with increasing pH, and then increased after pH>7, implying obvious pH sensitivity of the particles.The relevant Zeta potential of the particles also decreased gradually, and changed to a negative value.This transition can explain reasonably the pH sensitivity of the microgel.

    Synthesis of polyaspartic acid derivative and its characteristics in scale inhibition
    GAO Yuhua, LIU Zhenfa, GUO Ruhui, WANG Yanji
    2009, 60(8):  2107-2111. 
    Abstract ( 1044 )   PDF (1013KB) ( 434 )  
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    Polyaspartic acid derivative was prepared from aspartic acid(ASP)and polysuccinimide(PSI)that was the thermal condensation polymer of ASP.Its grafting ratio was examined by measuring the residual ASP.Effect of the mole ratio of PSI to ASP on grafting ratio and the scale inhibition properties of PASP-ASP were studied.The product structure was characterized by using FTIR.Calcium carbonate crystals in the scale samples were observed with SEM.The highest grafting ratio of PASP-ASP up to 66.45% was achieved when the mole ratio of PSI to ASP was 1∶1.8.Under the concentrations of Ca2+ with 400 mg•L-1,HCO-3 with 800 mg•L-1 and PASP-ASP with 6 mg•L-1,the scale inhibition efficiency of PASP-ASP was up to 100%.Polyaspartic acid derivative could make the calcium carbonate crystallite more distortive and more dispersive.

    Synthesis of ester-tin(butyl acrylate) and processing stability for PVC
    ZHANG Shuhua, LIU Bo, CAO Jian, ZHU Hui
    2009, 60(8):  2112-2117. 
    Abstract ( 884 )   PDF (774KB) ( 342 )  
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    Ester-tin (butyl acrylate) was synthesized by mixing solvent and phase transfer catalyst, and was characterized with IR and HNMR.Thermal stability was tested by means of rheometer and Color Quest XE.It was shown that ester- tin (butyl acrylate) exhibited good performance.The dynamic stability time was >50 min and initial stability time was >15 min at 180—190℃ for the ester-tin (butyl acrylate)/PVC compound system.The transparence decreased from 91.61% to 91.37% and yellowness increased from 1.86 to 3.51 after processing over 20 min on the plasticator.Ester-tin(butyl acrylate) can be used to produce PVC transparent products and PVC environmentally friendly products.

    Effect of triethanolamine on anodizing process of magnesium alloys
    OU Ailiang, YU Gang, HU Bonian, HE Xiaomei, ZHANG Jun, YI Haibo, CHEN Yun
    2009, 60(8):  2118-2123. 
    Abstract ( 1107 )   PDF (937KB) ( 669 )  
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    The effect of triethanolamine concentrations on the properties of anodizing film of AZ91D magnesium alloy was investigated by using constant current anodizing technique in electrolyte containing KOH, Na2SiO3, Na2B4O7 and triethanolamine etc.Properties of the anodizing coatings were evaluated by voltage-time curves, corrosion rate and polarization curves and the coating morphologies were characterized by using SEM.Experimental results revealed that triethanolamine has remarkable effect on arc restraining, which resulted in an increase in the anodizing film thickness and a decrease in the surface micro-hole size, and finally the improvement in the surface finish.The anodizing film obtained by anodic oxidation in a solution containing 30 g•dm-3 triethanolamine has good corrosion resistance.During the anodic oxidizing process, triethanolamine molecules are adhered by chemisorption to the surface of the magnesium alloy, through which the adsorption ability and the number of oxygen bubbles on the alloy surface decreased.Hence, the porosity of the obtained ceramic film is reduced, and the film density as well as its corrosion resistance is improved.

    Preparation of high purity precipitated silica from iron ore tailings by molten salt method
    YU Honghao, XUE Xiangxin, HE Yan, HUANG Dawei
    2009, 60(8):  2124-2129. 
    Abstract ( 1122 )   PDF (1024KB) ( 535 )  
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    The iron ore tailings were mixed with NaOH-NaNO3 and calcined at 500℃ for 3 h to produce soluble sodium silicate.The iron ore tailings and NaOH were used as raw materials, and NaNO3 was used as molten salt.The precipitated silica particle was prepared by using sodium silicate as a source of silicon by the chemical precipitation method.The composition, morphology and structure of the synthesized particles were characterized by X-ray diffraction (XRD), FTIR analysis, transmission electron microscopy (TEM) analysis, and X-ray fluorescence analysis (XRF).The SiO2 purity in the precipitated silica product was 99.3% by XRF.The chemical structure of precipitated silica was hydrated silicon oxide by FTIR analysis.The structure of precipitated silica was amorphous by XRD analysis.The TEM micrograph showed that the shape of precipitated silica particles was nearly spherical, and the average grain diameter was about 100 nm.The specific surface area was 152 m2 •g-1 by the BET method.

    Microwave synthesis optimization, structure and properties of CTA
    WEI Yunlu, ZHENG Cheng, NING Zhengxiang, SUN Baoxing
    2009, 60(8):  2130-2136. 
    Abstract ( 744 )   PDF (554KB) ( 549 )  
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    3-chlorine-2-hydroxypropyl triethyl ammonium chloride (CTA) was synthesized with epichlorohydrin, triethylamine muriate as raw materials under the irradiation of constant power microwave.Analysis by TLC and chemical titration indicated the purity of the product above 99.0% after the crystallization in the mixture of acetoacetate and ethanol.The structure of CTA was identified by IR and NMR.The factors which influenced the yield of CTA were investigated in terms of microwave power, reaction time, temperature and mole ratio of raw materials.Experimental results showed that the yield of CTA improved by 16.58% and the reaction time was 340 min shorter than the traditional method under the following reaction conditions: microwave power 300 W, 50℃, mole ratio of raw materials 1.15∶1, reaction time 20 min.Finally the CMC, surface tension, Krafft point and melting point of the CTA were determined.

    Direct synthesis and characterization of super-microporous SiO2 with spherical and cylindrical shapes
    HU Wenbin, CUI Yingde, YIN Guoqiang, Duncan J Macquarrie, LIAO Liewen, CHEN Xunjun
    2009, 60(8):  2137-2140. 
    Abstract ( 532 )   PDF (754KB) ( 237 )  
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    The direct synthesis of templated super-microporous silica with spherical and cylindrical shapes was achieved in a water/acetonitrile/n-dodecylamine system, using 3-mercaptopropyltrimethoxysilane and 3-trifluoromethyltrimethylsilane as co-template.The benefits of this system to prepare such silicas were high surface area, much enhanced wall thickness, and consequently to greater structural stability.The particles obtained from this route were spherical and cylindrical.The sample was characterized by using N2 adsorption /desorption, XRD, FTIR,SEM , TG-DSC and 13C CP MAS NMR methods,and the process of the direct preparation was given.