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Table of Content
05 July 2016, Volume 67 Issue 7
    CIESC Journal(HUAGONG XUEBAO)Vol.67 No.7 July 2016
    2016, 67(7):  0-0. 
    Abstract ( 156 )   PDF (2137KB) ( 295 )  
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    A review on regulation methods of nitrite oxidizing bacteria in one-stage anaerobic ammonia oxidation process
    XIE Li, YIN Zi, YIN Zhixuan, WANG Yuechao, ZHOU Qi
    2016, 67(7):  2647-2655.  doi:10.11949/j.issn.0438-1157.20160294
    Abstract ( 383 )   PDF (625KB) ( 569 )  
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    In recent years,anaerobic ammonium oxidation (Anammox), a new technology for nitrogen removal, has been used in the treatment of high-strength ammonia wastewater due to its low energy consumption and high treatment efficiency. Whereas, the accumulation of nitrite oxidizing bacteria (NOB) often occurs in full-scale Anammox process, leading to the accumulation of nitrate and deterioration of nitrogen removal effectiveness. In two-stage Anammox processes, NOB accumulation often occurs in partial nitritation stage, the inhibition of which has been discussed in details. While in one-stage Anammox process, NOB accumulation is more common and fatal due to the complexity brought by the coexistence of functional bacteria like ammonium oxidizing bacteria (AOB), NOB, anaerobic ammonia oxidizing bacteria (AnAOB) and denitrifiers. It has been reported that NOB could be effectively suppressed in the one-stage Anammox process by some methods, e.g. regulating dissolved oxygen, altering the free ammonia and free nitrous acid concentration, adjusting carbon source and adding externally intermediate products (N2H4, NO, NH2OH), etc. The regulation methods mentioned above are systematically introduced on the basis of previous reports. Moreover, in practical Anammox crafts, the inhibitory methods should be conducted according to the specific operational conditions, and thus the available methods are further discussed.

    Metabolic engineering for efficient microbial production of 2,3-butanediol
    TONG Yingjia, WU Wenjia, PENG Hui, LIU Lugang, HUANG He, JI Xiaojun
    2016, 67(7):  2656-2671.  doi:10.11949/j.issn.0438-1157.20160209
    Abstract ( 460 )   PDF (725KB) ( 1049 )  
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    2,3-butanediol (2,3-BD), which is considered as an important microbial metabolite, has been widely used in many fields such as food, medicine, chemical, and so on. Microbial 2,3-BD production has a history of more than 100 years, but the low efficiency of microbial 2,3-BD accumulation has constrained its process in biological manufacturing industrialization. Optimization of microbial metabolic pathway with the theory and method of metabolic engineering is expected to solve this problem. The objective of this paper is to review the state-of-the-art strain transformation and construction strategies in microbial synthesis of 2,3-BD, including overexpressing genes encoding for key enzymes in the 2,3-BD metabolic pathway, knocking out the metabolic bypass way genes, and using the methods of cofactor engineering in redesigning and reasonable transformation of the natural strains' metabolic network. Besides that, the using of synthetic biology in constructing brand new 2,3-BD pathways in model strains, such as Escherichia coli, Saccharomyces cerevisiae and Cyanobacteria, in order to enhance the yield or chiral 2,3-BD production in microorganisms is also introduced in this review. Finally, the future research direction is prospected, and the guidelines to develop high-efficiency microbial cell factories by advanced synthetic biology methods to achieve the optimal allocation of the intracellular metabolic flow are also proposed.

    Conductivity estimates of liquid hydrocarbons by finite element analysis in vibration mechanics
    QIU Minghua, LIU Wanqiang, CHEN Guanfan, LIU Fengping, YUE Ming
    2016, 67(7):  2672-2678.  doi:10.11949/j.issn.0438-1157.20151546
    Abstract ( 225 )   PDF (480KB) ( 218 )  
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    Given hydrocarbon molecular structures as elastomers, three dimentional (3D) molecular structure of hydrocarbons was analyzed by finite element analysis in vibration mechanics. The stiffness matrix and vibration equation of molecular structure system was established, and its eigen values of inherent frequency and stiffness matrix were obtained by calculation using MATLAB software, followed by QSPR model for the liquid hydrocarbon conductivity by multivariate regression method. For training set consisting of 581 liquid hydrocarbons, the correlation coefficient R between the calculated values of liquid conductivity using QSPR model and the experimented data is 0.9874, the mean absolute error less than 0.00259 W·m-1·K-1, and the relative error less than 2.39%. For testing set comprising 22 liquid hydrocarbons, the correlation coefficient R is 0.9550, the mean absolute error less than 0.00263 W·m-1·K-1, and the relative error less than 2.42%. It showed that the calculated values by this QSPR model fit experimental data well in terms of conductivity of liquid hydrocarbon. It can be used to estimate the liquid conductivity of complex hydrocarbons such as acyclic alkanes, alkenes, alkynes, monocycle alkanes, polycyoalkanes, decahydronaphthalenes, fluorene alkanes, perhydrophenanthrenes, indene alkanes, and pinanes.

    Measurement and prediction of speed of sound of three FAEEs
    ZHENG Xiong, CHEN Yutian, ZHANG Ying, HE Xinxin, LIANG Lili, HE Maogang
    2016, 67(7):  2679-2684.  doi:10.11949/j.issn.0438-1157.20160236
    Abstract ( 335 )   PDF (607KB) ( 358 )  
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    Biodiesels are regarded as the promising additives for fossil fuels, and fatty acid ethyl esters (FAEEs) are the main components of biodiesels. In order to obtain their speed of sound data, the speed of sound of three FAEEs were measured in this work using Brillouin light scattering method at temperatures from 293.15 K to 473.15 K and pressure of 0.1 MPa. The correlation for the speed of sound was also fitted as the function of temperature. The AAD was 0.13% for ethyl hexanoate, 0.11% for ethyl cinnamate and 0.08% for ethyl caprylate. The experimental data were also used to assess the predictive ability of Wada's model and Auerbach's model. It was shown that the former performed better than the latter one for the prediction of speed of sound of FAEEs.

    Vapor-liquid equilibrium for methanol + polyoxymethylene dimethyl ethers binary system under normal atmospheric pressure
    WANG Fengyang, LIANG Huanhuan, ZHOU Cairong
    2016, 67(7):  2685-2691.  doi:10.11949/j.issn.0438-1157.20151985
    Abstract ( 280 )   PDF (523KB) ( 357 )  
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    At 101.3 kPa constant pressure, the VLE data of methanol-DMM3 (polyoxymethylene dimethyl ethers with degree of polymerization of n, i.e., DMMn) system were determined by using an improved Rose still. Thermodynamic consistency of the obtained vapor liquid equilibrium data were examined. The results were satisfied with Gibbs-Duhenm's thermodynamic consistency. The VLE data were correlated by Wilson, NRTL and UNIQUAC activity coefficient model by Aspen Plus v7.1. The objective function was optimized by the maximum likelihood method and the corresponding model parameters were returned. Compared with the experimental results, the average absolute deviations for temperature and the composition in the vapor phase were less than 0.65 K and 0.0065, respectively. This work provides the important engineering data for an engineering design and further study in the multicomponent system containing methanol and DMM3.

    CFD simulation of cross flow in multi-tubular fixed-bed reactor of industrial level
    YANG Yao, GE Shiyi, HUANG Zhengliang, SUN Jingyuan, WANG Jingdai, LIAO Zuwei, JIANG Binbo, YANG Yongrong
    2016, 67(7):  2692-2701.  doi:10.11949/j.issn.0438-1157.20160047
    Abstract ( 372 )   PDF (2945KB) ( 570 )  
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    The conversion and selectivity of an extremely large multi-tubular fixed-bed reactor of industrial level remarkably relate to the distribution homogeneity of temperature and flow of heat transfer medium in shell side. In this work, through introducing two items of resistance source and a dispersed heat transfer source, the distribution of temperature and flow in the shell of a multi-tubular fixed-bed reactor of industrial level for butane oxidation to maleic anhydride was investigated by CFD simulation. Subsequently, effects of the window size and the location of baffles on the pressure drop of shell side and the distribution of temperature and flow were studied. It showed that the pressure drop of the shell side achieved by simulation are in good agreement with that by calculation of experimental equations, and the simulated temperature distribution of shell side is in accordance with industrial experimental data. With an increase in window area of the baffles, the pressure drop of shell side exponentially decreased, the range of large temperature difference (with a radial temperature difference greater than 2 K), and the radial temperature difference increased. With a decrease in height of the first baffle, both the range of large temperature difference and the radial temperature difference reduced, while the pressure drop of shell side did not show any consistent changes. Here the modeling strategy can be a good way to optimize the design of extremely large multi-tubular fixed-bed reactor of industrial level.

    Solutal Marangoni convection by Schlieren method
    ZHAO Song, CHEN Man, ZENG Aiwu, JIN Wu
    2016, 67(7):  2702-2708.  doi:10.11949/j.issn.0438-1157.20160263
    Abstract ( 288 )   PDF (3377KB) ( 271 )  
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    Marangoni convection in the physical desorption of carbon dioxide from ethanol solvent was studied experimentally. Evolution of the convective structures on the free surface of liquid layers was captured through Schlieren method. Especially, its initial form was captured under appropriate procedures. Each structure changed from approximately round to polygon because of space restriction. Mechanism of the Marangoni convection in mass transfer process was deduced from the luminance distribution of Schlieren images. The emergence, development and fission of a single structure were analyzed qualitatively. Interfacial turbulence caused by the non-uniform mass transfer process led to the deformation of free interface. Finally, the entire surface was filled with polygonal structures with its shape fixed. Fading color in the Schlieren images can reflect the decrease of turbulent intensity during the desorption process, which can be attributed to the change of mass transfer driving force.

    Effect of curvature and undercooling degree of surface on behavior of droplet spreading
    FAN Yao, WANG Hong, ZHU Xun, HUANG Geyong, DING Yudong, LIAO Qiang
    2016, 67(7):  2709-2717.  doi:10.11949/j.issn.0438-1157.20160224
    Abstract ( 422 )   PDF (5608KB) ( 519 )  
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    To considerate the harmness and the icing type of the power transmission line, the glaze was the most deadly harmness to the power transmission line than the other icing types. Dynamic characteristics of droplets impacting on the solid surface has a significant effect on the mechanism of heat and mass transfer during the phase transformation as well as the mechanism of the conductor ice coating. The evolution behaviors of droplets impacting on the different temperature curved surfaces were investigated by the visional experiments. It showed that the effects of the different undercooling degree and the surface curvature on the law of droplet spreading behavior. The results indicated that the circumferential liquid film spread out better and the axial one did worse with the increase of cylindrical surface curvature. Increasing the surface undercooling degree, the droplet spread worse and oscillation time became shorter and the upper film freeze faster on the undercooling surface. However, the droplet impacting on undercooling surface spread better than that at ambient temperature. It was speculated that there was an ice film formed rapidly at the bottom of the droplet when it spread on the cold solid surface by analyzing the effects of the surface tension and viscosity of water droplet on the spread behavior. The ice film, which obviously altered the interface energy between the solid phase and liquid phase, made the droplet spread easily. The ice film was distinctly observed at the droplet recoiling stage. The conclusion can provide theoretical reference for glaze ice on the conductors.

    Performance experiment of thermoelectric dehumidification device used for medicine storage and its parameter optimization
    ZHANG Teng, SHEN Limei, CHEN Huanxin, YANG Zonghao
    2016, 67(7):  2718-2723.  doi:10.11949/j.issn.0438-1157.20151640
    Abstract ( 338 )   PDF (751KB) ( 222 )  
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    Thermoelectric cooling dehumidification is a new dehumidification technology of energy conservation and environmental protection. Due to the efficiency and the velocity of the thermoelectric dehumidification device is relatively low, a thermoelectric dehumidification device using two TEC-12705 thermoelectric coolers was designed, and these two coolers were diagonal arranged. The factors affecting the performance of the thermoelectric device was analyzed systematically and the corresponding design and optimization conception were put forward according to the actual condition. The results showed that the wind speed, the driving voltage and the air flow organization form had a certain influence on the performance of the thermoelectric cooling device. The capacity of heat transfer and the contact time between the air and the cold sink should be considered comprehensively when the wind speed was determined.

    Combustion characteristic of hydrogen non-premixed micro-jet flames
    ZHANG Jing, LI Xing, YANG Haolin, JIANG Liqiao, WANG Xiaohan, ZHAO Daiqing
    2016, 67(7):  2724-2731.  doi:10.11949/j.issn.0438-1157.20160119
    Abstract ( 261 )   PDF (3156KB) ( 300 )  
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    Non-premixed hydrogen micro-jet flames in co-flow airs were studied by numerical computations with a detailed chemical reaction mechanism. The results of numerical computations agreed reasonably well with the counterparts of the experiments. The results showed that the computed maximum flame temperature decreased with decreasing fuel injection velocity for a fixed micro tube. When the fuel injection velocity was close to the minimum flow velocity sustaining a flame, the computed maximum flame temperature decreased sharply with decreasing fuel velocity. The wall materials had an influence on flame structures at a low fuel velocity. The lower the thermal conductivity of materials, the higher the wall temperature near the nozzle exit. The maximum flame temperature on the axis was relative higher. However, the effect of thermal conductivity on the quenching velocity of flame was not remarkable.

    Numerical simulation of gas-liquid flow in stirred tanks based on EMMS model
    XIAO Qi, YANG Ning
    2016, 67(7):  2732-2739.  doi:10.11949/j.issn.0438-1157.20160006
    Abstract ( 338 )   PDF (5019KB) ( 655 )  
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    3D Eulerian-Eulerian model was applied to simulate the flow in a gas-liquid stirred tank. Simulation results with different drag models were evaluated at the discharge flow region. CFD simulation could correctly predict the liquid velocity distribution around the impeller, but the traditional Schiller-Naumann drag model under-estimates the drag force, leading to the relatively lower gas holdup at the region under the impellers and gas distributor. The DBS-Global drag model derived from the gas-liquid EMMS model could obtain more reasonable gas holdup distribution at the complete dispersion regime and significantly improved the prediction accuracy of the gas holdup distribution at the discharge flow region.

    Experimental measurement and structure optimization of heat recovery exchangers on rotary kilns
    YIN Qian, DU Wenjing, JI Xinglin, CHENG Lin
    2016, 67(7):  2740-2747.  doi:10.11949/j.issn.0438-1157.20160093
    Abstract ( 338 )   PDF (1109KB) ( 347 )  
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    A novel heat recovery exchanger installed on the rotary kiln shell surface is proposed in this paper. The heat recovery exchanger contains water tubes and coiled pipes, which function as the radiative and the convective heat transfer surfaces, respectively. Numerical studies and experimental measurements are carried out to investigate the heat transfer characteristics of the heat exchanger. Several optimization models are proposed with the heat transfer area, the pressure drop and the modified entropy generation numbers set as the objective functions. The models describe the relation between the heat transfer rates and structural parameters of the heat recovery exchanger, i.e. the tube length, the tube numbers and the tube diameter. The optimized design parameters are obtained by applying the genetic algorithm toolbox in Matlab. The results indicate that the optimized heat transfer areas of water tubes and coiled pipes are decreased by 15% and 20%, respectively. The corresponding pressure drop is significantly decreased after optimization. In the optimization process, the modified entropy generation numbers are decreased due to fluid friction, while the modified entropy generation numbers remain unchanged due to heat transfer.

    Parallel algorithm of CFD-DEM model and applications on gas-solids flow in fluidized beds
    YANG Chunzhen, CHEN Chengmin, LIU Guangxia, DUAN Yufeng
    2016, 67(7):  2748-2755.  doi:10.11949/j.issn.0438-1157.20160026
    Abstract ( 250 )   PDF (2222KB) ( 567 )  
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    General domain coverage method (GDCM) was proposed to determine the region for each computing node efficiently by comparing all cell nodes, where these regions were helpful for Host to identify which computing node solid particle belongs to. Particle information was passed among host and nodes with the help of Fluent UDFs. The parallel algorithm for CFD-DEM model was developed successfully to simulate gas-solids flows in the fluidized beds (FBs) which were meshed in arbitrary shapes. Based on the comparison of calculation efficiency between parallel algorithm and serial algorithm, the bubble behaviors were studied in a FB with an immersed tube in a single jet FB, and the solids exchange behaviors between two half beds were simulated and compared with experimental results in a dual leg FB. The simulation results showed that the particle information was passed between host and nodes efficiently by parallel algorithm. It was efficient for GDCM to determine which computing node particles are in. The simulated bubbling frequency (about 3 Hz) was similar as Rong's simulation result. Compared with Bokkers' simulated and experimental jetting bubble size, the more similar bubble size and solid velocity vectors around the bubble were obtained by the parallel algorithm. The solid exchange between two half beds in both forms of the first (~1 Hz) and second (>2 Hz) domain frequency was simulated, which was similar as the experimental result.

    Influence of structure on drainage performance of metal foam
    LAI Zhancheng, HU Haitao, ZHUANG Dawei, DING Guoliang
    2016, 67(7):  2756-2760.  doi:10.11949/j.issn.0438-1157.20151958
    Abstract ( 267 )   PDF (2155KB) ( 268 )  
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    Metal foam has very large specific surface area, and it has great potential in dehumidification. The key for designing metal foam heat exchanger for dehumidification is to promote the drainage performance of metal foam. The influence of structure factors on drainage performance of metal foam with three different surface wettability was investigated by dynamic dip test in this study. The results showed that, the drainage performance was deteriorated with the increase of pore density or height and promoted with the increase of porosity. For hydrophobic samples, the drainage performance of 5—40PPI metal foams was promoted, while water retention was reduced by 26%—60%. For hydrophilic samples, the drainage performance of 5—10PPI metal foam was promoted with the maximum reduction of water retention of 23%, while the drainage performance of 15—40PPI metal foam was deteriorated with the maximum increment of water retention of 13%.

    Capillary performance of metal porous media for heat transfer enhancement
    TU Wenbin, WANG Yun, TANG Yong
    2016, 67(7):  2761-2766.  doi:10.11949/j.issn.0438-1157.20151434
    Abstract ( 297 )   PDF (6680KB) ( 287 )  
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    Metal porous media which enables the gas and liquid separation is adopted to enhance heat transfer. Due to the different mechanical behavior between gas and liquid in the porous wall, the gas-liquid two-phase can be separated along the porous media insert, where gas cannot enter the porous wall and the liquid is free to flow in the center. Thus, the gas can flow along the tube wall and the liquid flow in the center of the tube, leading to a high heat transfer performance. Capillary force of the porous media has an important influence on the enhancement performance. In this paper, a novel capillary force testing method is used to test the capillary force of the metal porous media inserts. It is found that the capillary force of the porous media is associated with the powder material, particle size and the filling of the porosity. The particle shape is the most important factor affecting the capillary force and then the particle size, while the porosity is the weakest one.

    Influences of external moisture content in pulverized coal on discharge characteristics of top discharge blow tank
    XU Guiling, LU Ping, XU Pan, LIANG Cai, CHEN Xiaoping
    2016, 67(7):  2767-2776.  doi:10.11949/j.issn.0438-1157.20160129
    Abstract ( 287 )   PDF (2049KB) ( 229 )  
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    Experimental investigations on the discharge characteristics of pulverized coal with different external moisture content were carried out in a dense-phase pneumatic conveying facility of top discharge blow tank. The effects of external moisture content on solid discharge rate, solid loading ratio and discharge stability were investigated. The limit and the best values of external moisture content for Neimenggu lignite used in the experiments were obtained. Combined with flowability analysis of the pulverized coal, the discriminate methods of limit and the best external moisture content for discharge process were discussed. The results showed that for pulverized coal with original external moisture content of 3.3%, an obvious electrostatic discharge phenomenon could be observed near the wall of the top discharge blow tank and the riser inlet during the discharge process. When the pulverized coal external moisture content was increased to 10%, arching phenomenon would appear in the top discharge blow tank. The limit external moisture content for Neimenggu lignite was in the range of 8.7%—10%, and its best external moisture content was about 4% corresponding to the maximum solid discharge rate and solid loading ratio, and to the best discharge stability. When the external moisture content was 4%, equal to the best external moisture content obtained by discharge experiments, the flow function reached the maximum value, the cohesion reached the minimum value and the pulverized coal flowability became the best. When the external moisture content was increased from 8.7% to 10%, the pulverized coal flowability turned from the easy flow region to cohesive region and the flowability became worse. When the external moisture content was 10%, the pulverized coal was in the cohesive region which meant difficult to flow. Compared with discharge experiments, the flow function and cohesion obtained by the shear tests could be used as preliminary criterion to judging the limit and best values of external moisture content pulverized coal in industrial applications more conveniently.

    Modeling and control simulation of a small-scale diffusion flame under direct-current electric fields
    SHI Yanling, GAN Yunhua
    2016, 67(7):  2777-2783.  doi:10.11949/j.issn.0438-1157.20151470
    Abstract ( 223 )   PDF (624KB) ( 259 )  
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    Charged particles in the flame produced by combustion of hydrocarbon fuels provided an alternative control option via external electric fields. The liquid ethanol was used as fuel. A stainless steel tube with an inner diameter of 0.9 mm was used as the nozzle and an external direct-current electric field was applied. The voltage-current characteristics of a small scale diffusion flames under the electric field were identified. The combustion system can be assumed as an equivalent circuit model. According to the theory of circuit, the change rules of flame equivalent resistance were obtained. The ion production was used as a sensor and a classical simple PID closed control method was used to adjust the flame. The simulation results showed that the system designed in present paper had well anti-jamming capability. The present study can supply some certain guidelines for the control and stable operation of microscale combustor.

    Numerical simulation of droplet impinging and freezing on cold surfaces with different wettability
    LENG Mengyao, CHANG Shinan, DING Liang
    2016, 67(7):  2784-2792.  doi:10.11949/j.issn.0438-1157.20151888
    Abstract ( 318 )   PDF (2049KB) ( 565 )  
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    A strategy is presented to simulate the impact and solidification of the water droplet on different substrates. Simulations were performed using a coupled volume-of-fluid and level-set method to tracking the air-water interface and an enthalpy-porosity method to capture the phase transition. Three surface types were investigated: hydrophilic surface (contact angle 30°), hydrophobic surface (contact angle 114°) and superhydrophobic surface (contact angle 163°). The results showed that decreasing the wettability would reduce the contact time and area with the cold surface, and delay the freezing of the droplet. When temperature of the surface is higher than -15℃, the superhydrophobic surface can remain entirely ice-free under the simulated conditions. By comparing the maximum droplet spread, retraction response and time for solidification with the experimental results, the effectiveness and precision of the simulation strategy were demonstrated.

    Hydrogenation of high-concentration monovinylacetylene for butadiene production over Pd-Pb/SiO2 catalysts
    ZHANG Yike, JIA Zekun, ZHANG Shuai, ZHEN Bin, HAN Minghan
    2016, 67(7):  2793-2798.  doi:10.11949/j.issn.0438-1157.20160160
    Abstract ( 432 )   PDF (511KB) ( 330 )  
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    The hydrogenation of high-concentration monovinylacetylene over silica supported Pd-Pb bimetallic catalysts was investigated. It showed that the appropriate presence of Pb can prevent Pd nanoparticles from aggregation, hence facilitated the improvement of catalytic activity, i.e. the optimal molar ratio of Pb to Pd of 0.2. With the molar ratio of Pb to Pd above 0.2, Pd-Pb alloy can be formed, which causes catalytic activity loss. The positive correlation between the catalytic activity and the electron bonding energy of Pd 3d was manifested by X-ray photoelectron spectra. The temperature for PdO reduction exhibited a remarkable influence on the structure and the activity of the catalysts. The PdO reduction at 350℃ of the catalyst was incomplete thus with low activity. At 450℃ of the reduction temperature, it caused Pd nanoparticle sintering, hence with low activity and low butadiene selectivity. As a result, the optimal reduction temperature was 400℃. After 40 h, the catalyst was deactivated due to the blockage of pore by coke formation on catalyst surface. Subsequently, the improvement of anti-coking ability and the lifetime of the catalyst will be of interest.

    Sulfonic acid functionalized MIL-101(Cr) catalysts with tunable Lewis acid and Brönsted acid sites for glucose dehydration to 5-HMF
    SU Ye, BAO Zongbi, ZHANG Zhiguo, XING Huabin, YANG Qiwei, SU Baogen, YANG Yiwen, REN Qilong
    2016, 67(7):  2799-2807.  doi:10.11949/j.issn.0438-1157.20160115
    Abstract ( 402 )   PDF (2881KB) ( 558 )  
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    A series of Cr-terephthalates metal-organic frameworks functionalized by sulfonic acid group (-SO3H) [MIL-101(Cr)-SO3H], featuring varied ratios of Lewis acid site to Brönsted acid site, were synthesized by hydrothermal reaction method starting from Cr(NO3)3·9H2O and sodium 2-sulfoterephthalate under various conditions of temperature and reaction time. The catalysts were characterized by techniques of PXRD, EDX, SEM, ICP-AAS and BET surface area, and the catalytic performances for glucose conversion to 5-HMF were evaluated. It showed that, in terms of the catalysis kinetics, Cr3+ serves as the Lewis acid sites of MIL-101(Cr)-SO3H for glucose isomerization, and sulfonic acid group, the Brönsted acid site for the fructose dehydration. The highest HMF selectivity of 47.15% and the highest HMF yield of 46.0% was achieved under conditions of molar ratio of Brönsted acid site to Lewis acid site of 1.1, 150℃ for 2 h.

    Reaction engineering calculation for ethylene catalytic oxidation over gear-shaped catalysts
    ZHOU Jipeng, FANG Dingye, LI Tao
    2016, 67(7):  2808-2814.  doi:10.11949/j.issn.0438-1157.20160081
    Abstract ( 236 )   PDF (3925KB) ( 389 )  
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    For the reaction of ethylene catalytic oxidation to ethylene oxide over a gear-shaped catalyst particle, a three-dimensional reaction-mass transfer-heat transfer model is developed to calculate effectiveness factor of the catalyst. Effective diffusivities and effective thermal conductivity are the function of temperature and concentration distribution in catalyst particle. The finite element method is employed to solve the set of highly nonlinear partial differential equations, and the values obtained agree well with those given by literatures. Geometric external surface area is a key parameter for the effectiveness factor. The effectiveness factor is 0.1804 for gear-shaped catalyst with geometric external surface area of 1862 m2·m-3, and 0.0993 for cylindrical catalyst with geometric external surface area of 924 m2·m-3. The quantitative calculation for reaction-transport phenomena in a single catalyst particle could be a guide for catalyst design and a basis for multi-scale simulation of coupling hydromechanics and catalytic reaction-transport phenomena.

    Kinetics of homogeneous polymerization of 1-decene over metallocene/organic boride catalytic system
    JIANG Hongbo, FAN Zongming
    2016, 67(7):  2815-2823.  doi:10.11949/j.issn.0438-1157.20151825
    Abstract ( 314 )   PDF (666KB) ( 237 )  
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    The 1-decene was polymerized over metallocene catalytic system of rac-Et(1-Ind)2ZrCl2/C6H5NH(CH3)2B(C6H5)4/ Al(i-Bu)3, and the kinetics under various reaction conditions such as temperature and molar ratio of aluminum to zirconium was investigated. In order to obtain dynamic data for monitoring the reaction process, samples taken at different time were analyzed on monomer concentration by gas chromatograph (GC), and that on molecular weight of polymer by gel permeation chromatography (GPC). Based on the polymerization reaction mechanism and material balance, and the hypotheses for alkene polymerization, the kinetic model of the polymerization was established. The model includes the reactions of chain initiation, chain propaganda, chain transfer to monomer, chain transfer to active center and chain termination. Levenberg-Marquardt algorithm was used to optimize the model parameters. Through the model, the reaction rate, number-average and weight-average molecular weights and so on can be predicted. By the validation experiments it showed that the values of model prediction are very close to the experimental data. The model prediction showed that the chain initiation reaction process was completed in a few seconds, the chain propagation reaction has lower activation energy than the chain transfer reaction, and higher temperature is beneficial to the chain transfer reaction.

    Synthesis of polyoxymethylene dimethyl ethers from methanol and formaldehyde catalyzed by ZnCl2
    SHI Midong, HE Gaoyin, DAI Fangfang, WANG Yunfang, LI Qingsong
    2016, 67(7):  2824-2831.  doi:10.11949/j.issn.0438-1157.20160226
    Abstract ( 353 )   PDF (832KB) ( 373 )  
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    Polyoxymethylene dimethyl ethers (PODEn) are kind of diesel fuel additives with features of environment friendly and high efficiency. PODEn were catalytically synthetized from methanol and formaldehyde by ZnCl2. In this work, the mechanism of the synthesis reaction was discussed, and the effects of preparation conditions, such as temperatures, time, usage of catalyst and reactant mass ratio were investigated. The comparison of different catalysts of ZnCl2, strong acid resin and ZnCl2 modified resin was carried out. The concentrations of the PODEn compounds and methanol were quantitatively analyzed using gas chromatography (GC), and formaldehyde was also determined by chemical titration method. Sulfuric acid standard solution was used to titrate sodium hydroxide formed by reaction of formaldehyde and excessive sodium sulfite. To obtain accurate experimental data, all the experiments were conducted strictly using the following procedures: poly-formaldehyde was de-polymerized to form anhydrous formaldehyde-methanol mixture solution; reaction device was heated to reaction temperatures (80, 95, 105 and 115℃); different proportions [2:(3—4)] of the mixture solution obtained, and ZnCl2 were added into reaction vessel; then, the pressurized vessel was sealed quickly and fixed, and rotational speed of the reaction device was set for 20 r·min-1; this moment was considered as the starting time of reaction; sampling time was placed after reacting 60—360 min. Reaction mechanism of synthetising PODEn from methanol and formaldehyde catalyzed by ZnCl2 was proposed as follows: formaldehyde was polarized firstly in the presence of catalyst, the first intermediate obtained came from the reaction of formaldehyde polarized and methanol, then other intermediates and PODEn were produced from the reactions of the first intermediate and raw materials. The experimental results confirmed that ZnCl2 could be used as catalyst for synthesis of PODEn from methanol and formaldehyde. The yield and selectivity of PODE2—6 reached 19.90%, 67.50%, respectively, when the better reaction conditions were used (mass ratio of methanol and formaldehyde 2:(3—4), catalyst usage 3.0% (mass), temperature 105℃ and reaction time 300 min). Content of the products was more than 10 percentage points higher for ZnCl2 modified resin catalyst which had higher catalytic activity than for ZnCl2 catalyst.

    Catalytic combustion of toluene over Cu-Mn mixed oxide catalyst
    GU Ouyun, LIAO Yongtao, CHEN Ruijie, JIA Lu, KAMEYAMA Hideo, LIN Yi, ZHOU Lü, MA Hua, GUO Yu
    2016, 67(7):  2832-2840.  doi:10.11949/j.issn.0438-1157.20151864
    Abstract ( 478 )   PDF (752KB) ( 484 )  
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    A series of copper manganese mixed oxide catalysts Cu1-xMnx (x 0—1.0) with high surface area were synthesized by using carbonate co-precipitation method and their performance in catalytic combustion reaction of toluene was investigated by varying the mole ratio of Cu and Mn. XRD, H2-TPR, XPS and N2 adsorption/ desorption were used to characterize the structure and textural properties of catalysts. The resulting Cu1-xMnx catalyst showed higher catalytic activity than mono-metal oxide catalyst, especially when a small amount of copper was doped into manganese oxide. With increasing the manganese content from 0 to 1.0, a volcanic tendency for catalytic activity was observed. Results of catalyst characterization revealed that the promoted catalytic activity can be associated with some interrelated factors, such as depressed crystallinity, highly dispersed oxide species onto the other, easier catalyst reducibility, more surface oxygen and enhanced surface area. It was difficult to attribute the promoted catalytic activity only to a single and specific factor. A synergistic effect between manganese and copper species was considered to be the most intrinsic reason.

    Numerical simulation of dynamic process during outside-in dead-end filtration in hollow fiber membrane module
    ZHUANG Liwei, DAI Gance
    2016, 67(7):  2841-2850.  doi:10.11949/j.issn.0438-1157.20160088
    Abstract ( 310 )   PDF (3282KB) ( 429 )  
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    A CFD model was developed based on the filtration in the dead-end outside-in hollow fiber membrane module. Various fiber length, diameter, permeability, packing density, fouling index and transmembrane pressure were chosen during numerical simulation of the dynamic evolution of flux distribution and permeate volumetric flow rate. The simulation revealed that the uniformity of flux distribution improved as the filtration processes. The self-adjustment of the flux distribution was more pronounced with longer, narrower, more permeable fibers, higher packing density, fouling index and trans-membrane pressure. The inverse of the water volumetric flow rate increased linearly with the accumulated volume of the permeate. Due to the non-uniformity of the flux distribution and its dynamic evolution, the linear relationship differed from the one presented in the classic cake filtration model. A correlation equation to characterize the dead-end outside-in cake filtration in the hollow fiber membrane module was obtained through curve fitting of the simulation data. The equation enabled the prediction of the module performance and better design of the module.

    Removal of phenols from aqueous solution by ionic liquid-molecular solvent composite extractant
    GUO Shaocong, YANG Qiwei, XING Huabin, ZHANG Zhiguo, BAO Zongbi, REN Qilong
    2016, 67(7):  2851-2856.  doi:10.11949/j.issn.0438-1157.20160149
    Abstract ( 329 )   PDF (515KB) ( 273 )  
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    Hydrophobic ionic liquid (IL)-molecular solvent composite extractant was developed for the removal of phenols from aqueous solution. The results showed that tetradecyltrihexylphosphonium bromide ([P66614]Br)-ethyl acetate mixtures could not only decrease the viscosity of extractant notably, but also have good affinity to phenols. The distribution coefficient of phenol in [P66614]Br-ethyl acetate-water biphasic system ([P66614]Br/ethyl acetate molar ratio 1:4) was 5.3 times higher than that using pure ethyl acetate as extractant, 9—60 times higher than those using several common hydrophobic ILs and only 25.3% smaller than that using pure [P66614]Br. The viscosity of 20% (mol) [P66614]Br mixture was only 1% of pure [P66614]Br. The solvation interactions calculated by COSMO-RS indicated that there were strong hydrogen-bonding interaction between the phenol and [P66614]Br, which drove phenol into the [P66614]Br-rich phase. This mixture also showed good extraction abilities for phloroglucinol, 4-chlorophenol and 2,5-dinitrophenol with distribution coefficients of 91, 490 and 1492, respectively. These results provided a new opportunity for designing phenol-removing solvent with both good thermodynamic and kinetic properties.

    Freeze-drying of porous frozen material with prefabricated porosity
    LI Hengle, WANG Wei, LI Qiangqiang, CHEN Guohua
    2016, 67(7):  2857-2863.  doi:10.11949/j.issn.0438-1157.20160080
    Abstract ( 288 )   PDF (8328KB) ( 268 )  
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    The porous frozen materials with prefabricated porosity were prepared to verify the effect on freeze-drying of liquid materials experimentally. Ceftriaxone sodium, a kind of commonly used antibiotics for injection, was selected as the primary solute in aqueous solution. Liquid nitrogen ice-cream making method was adopted to fabricate frozen materials with certain initial porosity. Freeze-drying experiments were conducted at the same operating conditions for two kinds of frozen materials, the initially unsaturated and saturated ones for comparison. The results showed that freeze-drying could be enhanced significantly using the porous frozen materials with prefabricated porosity. The drying time for the initially unsaturated frozen sample (S0=0.3 or 0.67 of initial porosity) can be 21.3% shorter than that required for the saturated one (S0=1.00 or zero porosity). SEM images of dried products displayed that the unsaturated materials had more tenuous solid matrix and continuous void space than those of the conventional one. This would be beneficial to migration of sublimated vapor and desorption of adsorbed moisture, favoring reduction of mass transfer resistance. Freezing rate had a little effect on freeze-drying of two kinds of frozen materials. Annealing could decrease the drying times, which were 16.2% saved for the initially unsaturated sample and 14.8% for the saturated one. Appropriately increasing ambient temperature had a positive impact on the freeze-drying process, and the change in chamber pressure had little contribution to the process.

    Structural property and dehumidification performance of hierarchically porous aluminosilicates
    LIU Qiao, WEI Xiaolan, DING Jing, WANG Weilong, HUANG Xiang, YANG Jianping
    2016, 67(7):  2864-2873.  doi:10.11949/j.issn.0438-1157.20151792
    Abstract ( 385 )   PDF (2677KB) ( 333 )  
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    Hierarchically porous aluminosilicate with high adsorption capacity and fast desorption kinetics was synthesized via hydrothermal method. Samples under different pre-crystallization temperature were synthesized. It was revealed that the excellent performance of adsorbents was attributed to its unusual pore texture. The adsorbents were characterized by N2 physisorption, XRD, TEM, FT-IR and NMR. The water vapor adsorption-desorption isotherms were measured on a dynamic vapor sorption system (DVS). The results of characterization showed that the adsorbent framework consisted of ordered mesoporous with microporous-like pits. As the pre-crystallization temperature raised, the proportion of microporous-like pits increased and the deep dehumidification performance was improved as more Al substituted in the framework. However, the amount of ordered mesopore and total pore volume decreased, leading to lower saturated adsorption capacity and water-desorbed percent. The hierarchically porous aluminosilicate showed its advantages for rotary dehumidifiers with deep dehumidification performance (relative humidification, RH 15%, 200 mg·g-1), high saturated adsorption capacity (RH 40%, 400 mg·g-1) and fast desorption kinetics under low desorption temperature (87℃).

    Development and adsorption properties of diatomite-LiCl composite desiccant
    ZHENG Xu, WANG Ruzhu, GE Tianshu
    2016, 67(7):  2874-2879.  doi:10.11949/j.issn.0438-1157.20160048
    Abstract ( 342 )   PDF (1317KB) ( 390 )  
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    Diatomite-LiCl composite desiccant was fabricated by impregnating LiCl into pores of porous diatomite. The surface area and pore parameters of composite desiccant were measured by Micromeritics gas adsorption analyzer (ASAP 2020). With improvement of the analyzer, water sorption capacity of composite desiccant was tested and compared to pure diatomite and conventional silica gel. Researches on nitrogen adsorption suggested that due to the impregnated salt particles, the surface area and pore volume of composite desiccant were smaller than pure porous media. Water sorption tests showed that the composite sample had water uptake much higher than that of pure diatomite and silica gel. Besides, sorption characteristic curves were fitted based on Polanyi potential theory. The result showed that the curve of composite desiccant could be divided into three sections.

    Synthesis of pyridinium based polymerized ionic liquid and its adsorptive desulfurization performance for thiophenic sulfurs from oil
    LI Chunxi, XU Huihui, ZHU Xuexi, LU Yingzhou, MENG Hong
    2016, 67(7):  2880-2886.  doi:10.11949/j.issn.0438-1157.20160104
    Abstract ( 284 )   PDF (1995KB) ( 402 )  
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    By using 4-vinyl pyridine (VP) and p-xylylene dichloride (PXDC), a PVP-PXDC, a highly crosslinked polymerized ionic liquid, was synthesized through radical polymerization and quaternary crosslinking reaction. In terms of composition, structure, morphology, thermal stability, specific surface area and pore structure of the ionic liquid polymer, it has been characterized by techniques of gel permeation chromatography, elemental analysis, infrared spectroscopy, scanning electron microscopy, thermo gravimetric analyzer and N2-adsorption, respectively, followed by the performance evaluation as adsorbent for desulfurization. It showed that the mesoporous ionic liquid polymer features 17.8 nm of average pore size, 56.9 m2·g-1 of specific area of and above 250℃ of decomposition temperature. The ionic liquid polymer was achieved by synthesis of the linear PVP polymer (160000 of weight-based mean molecular weight) followed by crosslinking with PXDC at molar ratio of VP/PXDC of 2:1 in DMF solvent. Its adsorption capacities for 1000 mg·kg-1 DBT, BT and T in a representative oil, are 5.65, 5.48 and 4.53 mg S·g-1 at 303 K and mass ratio of oil/adsorbent of 50:1, respectively, which are much higher than those of conventional pyridinium based ionic liquids. Moreover, the adsorption isotherms follow Freundlich equation.

    Purification of nitro T acid raffinate by nanofiltration membrane technology
    SHI Hu, LU Jianming, CHEN Zhong, LIN Xiao
    2016, 67(7):  2887-2892.  doi:10.11949/j.issn.0438-1157.20160076
    Abstract ( 248 )   PDF (1682KB) ( 267 )  
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    Production of nitro T acid which is an intermediate of H acid produces a large amount of waste acid. In this paper, the complex extraction coupled with nanofiltration membrane using trialkylamine (N235) as extracting agent was adopted to purify this waste acid in order to remove the residual extractant and soluble sulfonated naphthalene. The suitable extraction condition for nanofiltration processing was N235 volume fraction of 33%, water over oil ratio of 2:1 without addition of n-octanol. After secondary extraction, the removal rate of CODCr was 79%. When the secondary raffinates were concentrated to one sixth of the volume by nanofiltration, the average fluxes of the membranes were 9.9—20.9 L·m-2·h-1. Sulfuric acid with 27% concentration (mass fraction) was recovered. The total removal rates of CODCr and chroma were 94%—97% and 99%, respectively. This coupling method could greatly reduce the pollutant emissions in production of nitro T acid.

    Comparison of three silica resins in chromatographic property for mixed-mode chromatography
    DONG Binbin, XIA Haifeng
    2016, 67(7):  2893-2900.  doi:10.11949/j.issn.0438-1157.20160095
    Abstract ( 224 )   PDF (597KB) ( 300 )  
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    Spherical silica gel with a diameter of 5 μm and pore size of 30 nm was activated by KH-560 and coupled with three kinds of ligands (3-aminopyridine, 2-mercapto benzimidazole and 2-mercapto-1-methylimidazole) to prepare the high performance hydrophobic charge-induction chromatography (HPHCIC) column. The chromatographic properties of three columns were compared and evaluated with three model proteins (Lysozyme, BSA and IgG). The column with 2-mercapto-1-methylimidazole as ligand displayed a proper chromatography and separation behavior which controlled by pH. This work demonstrated that the novel synthetic materials can be utilized as the media of high performance hydrophobic charge induction chromatography.

    Mass transfer performance of CO2 absorption into DEA/ethanol solution in microchannel
    ZHOU Xu, WANG Xiaojing, ZHU Chunying, MA Youguang, XU Yiming
    2016, 67(7):  2901-2906.  doi:10.11949/j.issn.0438-1157.20151821
    Abstract ( 220 )   PDF (609KB) ( 334 )  
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    A high-speed camera was used to investigate the mass transfer process of CO2 chemical absorption into diethanolamine (DEA)/ethanol solution in microchannel. The volume evolution of the bubbles in the microchannel was obtained by the image-analysis method. By means of the gas pressure at the inlet and outlet of the microchannel, the average mass transfer coefficient (k) from the contact of two phases to equilibrium was attained. The influences of flow rates of gas and liquid and DEA concentration on the mass transfer coefficient were investigated. The experiment results indicated that k increased with increasing liquid flow rate and DEA concentration. For a given liquid flow rate and DEA concentration, k increased gradually up to a constant value with increasing gas phase flow rate. A correlation for estimating k was proposed and the calculated values by the present model agreed well with the experimental data.

    Robust PPLS model and its applications in process monitoring
    CHEN Jiayi, ZHAO Zhonggai, LIU Fei
    2016, 67(7):  2907-2915.  doi:10.11949/j.issn.0438-1157.20151439
    Abstract ( 151 )   PDF (648KB) ( 198 )  
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    A probability model can be developed by probabilistic partial least squares (PPLS) under the conditions that both principal components and errors satisfy Gaussian distribution. However, the expectation and variance of the Gaussian distribution is susceptible to outliers. As a result, the model is not robust for the real industrial process. This paper improves the robustness of the PPLS model based on the assumption that the raw data satisfy T distribution rather than Gaussian distribution. By adjusting the freedom degree of T distribution, the proposed robust probabilistic partial least squares (RPPLS) model can overcome the shortcomings of PPLS model. Furthermore, on the basis of RPPLS model, two monitoring indicators GT2 and GSPE are proposed to monitor the process state and the model changes, respectively. Comparing the monitoring performance in the TE process based on PPLS and RPPLS shows that RPPLS is more effective than PPLS in terms of the fault accuracy and the missing alarm rate.

    Fault detection method for uneven-length multimode batch processes
    GUO Jinyu, YUAN Tangming, LI Yuan
    2016, 67(7):  2916-2924.  doi:10.11949/j.issn.0438-1157.20151157
    Abstract ( 320 )   PDF (750KB) ( 438 )  
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    A fault detection algorithm for uneven-length multimode batch processes is proposed. First, the local weighted algorithm is used to preprocess the uneven-length batch data. In the training sample, the maximum retention length of uneven-length data is determined. Using the k-nearest neighbor information, the missing data points are reconstructed by weighting reconstruction. Secondly, the local neighbor normalized matrix is estimated for the training set of equal length. The K-means algorithm is used to classify the models. The local outlier factor method is used to determine the first control limits and remove outliers. Finally, the MPCA model is established and the second control limits are determined for each model. The unified statistics and control limits are calculated according to the matching coefficients of the control limit of the various models. The multimode fault detection is carried out under the unified control limits. The algorithm is applied to the semiconductor industrial process. Simulation results show that the proposed algorithm improves the fault detection rate relative to the traditional fault detection algorithms. The effectiveness of the proposed method is verified.

    Soft sensor method for moisture content of well oil based on automatic spectral clustering and multiple extreme learning
    LI Kun, HAN Ying, HUANG Haijiao
    2016, 67(7):  2925-2933.  doi:10.11949/j.issn.0438-1157.20151785
    Abstract ( 232 )   PDF (1610KB) ( 342 )  
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    Moisture content of the well oil is a key production variable in the oilfield, and it has great significance for improving the oil production efficiency by timely and accurate measurement of it. In order to overcome some deficiencies of the traditional manual measurement, the soft sensor technology is introduced to establish a soft sensor model based on automatic spectral clustering - multiple extreme learning machines (ASC-MELM). An automatic spectral clustering (ASC) algorithm is proposed and an improved firefly algorithm (FA) is applied to reach an optimal selection of the clustering number and the scale parameter. The proposed improved firefly algorithm (IFA) adopts a mechanism of jumping out of the current solution at a certain probability, which can avoid the deficiency of falling into the local optimal solution earlier of the traditional FA. For different training subsets after the clustering, the multiple extreme learning machines (ELM) are adopted to establish the different sub-models, in which IFA is used to reach an optimal selection of the hidden layer input weights, the hidden layer biases and the number of the hidden layer nodes. Finally, the output is obtained by calculating the weighted average of multiple sub-models. An application example of an oil well in a domestic oilfield is given. The simulation results show that the proposed method has better predicted accuracy and it is reasonable and effective to realize the soft sensor for moisture content of the well oil.

    Adaptive control for a class of uncertain pure-feedback nonlinear systems using Backstepping based on extreme learning machine
    LI Jun, SHI Qing
    2016, 67(7):  2934-2943.  doi:10.11949/j.issn.0438-1157.20151533
    Abstract ( 257 )   PDF (615KB) ( 236 )  
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    For a class of uncertain pure-feedback nonlinear dynamical systems, an adaptive neural control method using the extreme learning machine (ELM) is presented on the basis of mean value theorem and Backstepping control. As a kind of single-hidden layer feed forward networks (SLFNs), ELM, which randomly chooses hidden node parameters and analytically determines the output weights, shows good generalized performance at extremely fast learning speed. In the process of each step for the Backstepping controller design, the ELM network is used to approximate unknown nonlinear part of the subsystem. Meanwhile, the adaptive adjustment law of weights parameter by Lyapunov stability analysis is derived so that the semiglobal uniform ultimate boundedness of all signals in the closed-loop nonlinear system can be guaranteed and the output of the system can also converge to a small neighborhood of the desired trajectory. The employed control method is then applied to the instance of continuous stirred tank reactor (CSTR) system in the chemical process and the simulation results are presented to verify the effectiveness of the method.

    Effects of carbon chain length on dynamic interfacial tension between alkane and aryl alkyl sulfonate aqueous solutions
    NIU Ruixia, WANG Daqiang, WANG Jingling, WANG Chao, LIAO Lingzhi, SONG Hua
    2016, 67(7):  2944-2949.  doi:10.11949/j.issn.0438-1157.20151773
    Abstract ( 314 )   PDF (507KB) ( 218 )  
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    Using spinning drop method, the interfacial tensions between alkane and series of aryl alkyl sulfonate(CnNPAS, n=8,10,12,14,16)aqueous solutions were measured. The effects of the carbon number of alkane, the molecular weight of surfactant, the concentration of the surfactant and Na2CO3 on the interfacial tension were studied in detail. The results showed that the required time to reach the equilibrium interfacial tension increased with increasing molecular weight of the surfactant and content of Na2CO3. On the contrary, the higher carbon number of alkane and concentration of the surfactant, the less required time. The interfacial tension could be reduced obviously at a range of relative low surfactant concentrations, and then went through a minimum and eventually increased with increasing concentration.

    Effect of Ni/Co/Mn molar ratio on structure and electrochemical properties of xLi2MnO3-(1-x)LiMO2 cathode material
    PENG Jiming, CHEN Yuhua, LIU Shicheng, HU Sijiang, WANG Hongqiang, LI Qingyu
    2016, 67(7):  2950-2955.  doi:10.11949/j.issn.0438-1157.20151501
    Abstract ( 285 )   PDF (3288KB) ( 399 )  
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    Li-rich layered cathode materials were synthesized by a facile co-precipitation method with NaOH and NH3·H2O. The effect of Ni/Co/Mn molar ratio on the structure, morphology and electrochemical properties of the as-prepared material were intensively investigated through X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge tests. The Li1.2Mn0.54Ni0.13Co0.13O2 sample had good crystallity, uniform distribution of particle size and excellent electrochemical performance. It delivered the largest initial discharge capacity (247.9 mA·h·g-1) and coulombic efficiency (75.1%) at 0.1C-rate. Furthermore, it showed a high discharge capacity of 236.2 mA·h·g-1 at 1C-rate and a capacity retention of 88.3% after 50 cycles.

    Effects of Brevibacterium flavum with directed mutagenesis of ilvN and co-expression of ilvBNC cluster on L-valine production
    ZENG Bangding, HUANG Qingeng, LIANG Ling, GUO Xiaolei, WANG Mingzi, SHI Qiaoqin, WU Songgang
    2016, 67(7):  2956-2962.  doi:10.11949/j.issn.0438-1157.20151935
    Abstract ( 235 )   PDF (1519KB) ( 299 )  
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    Acetohydroxy acid synthase (AHAS) and acetohydroxy acid isomeroreductase (AHAIR) encoded by ilvBN and ilvC are two key enzymes which play important roles in the biosynthetic pathway of L-valine. Brevibacterium flavum MD515 was used as the origin strain and site-specific mutagenesis was performed in its ilvN gene which coded for the regulatory subunit of AHAS, resulting in the obtainment of an anti-feedback inhibition gene, named ilvBN'C. Then, the ilvBNrC gene was ligased to plasmid pZ8-1 for construction of the recombinant plasmid pZ8-1-ilvBNrC, which was subsequently transfored into B. flavum MD515. With this method, the targeted transformant B. flavum MD515/pZ8-1-ilvBNrC showed better L-valine producing capacity of 29.5 g·L-1, 27.7% increase than that of original strain when it was cultured in 250 ml shake flasks. Meanwhile, the yield of leucine and isoleucine also increased while the alanine decreased. The biomass and growth rate were also increased. Moreover, fermentation experiments was performed in a 30 L fermentor and the results indicated that the L-valine productivity of B. flavum MD515/pZ8-1-ilvBNrC reached to 61.7 g·L-1 while the conversion rate of glucose/valine was up to 39.2%. The work finally made some simple investigations about the purification of L-valine in B. flavum MD515/ pZ8-1-ilvBNrC and B. flavum MD515. The results showed that the light transmittance of strain B. flavum MD515/pZ8-1-ilvBNrC was higher while the protein content was lower than that of B. flavum MD515, which was beneficial for subsequent separation process.

    Micro-emulsion method for reducing viscosity of petroleum sludge
    YANG Jie, LIU Tianlu, SONG Huibo, MAO Feiyan, HAN Xu, LIN Bingcheng, HUANG Qunxing, CHI Yong
    2016, 67(7):  2963-2969.  doi:10.11949/j.issn.0438-1157.20160004
    Abstract ( 308 )   PDF (3051KB) ( 388 )  
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    In order to reduce the viscosity of petroleum sludge for oil recovery, a micro-emulsion method was studied based on its rheological behavior. The effects of surfactant, micro-emulsion dosage and composition on the viscosity were discussed. The results indicated that the petroleum sludge could be classified as pseudo-plastic fluid and its strong shear-thinning force was attributed to the high content of solid particles in the petroleum sludge. The rheological behavior of petroleum sludge could be described by the P-L model. The results showed that the micro-emulsion could well mix with petroleum sludge and viscosity of the sludge was reduced by more than 95% by adding 25% micro-emulsion by mass. The maximum viscosity reduction was achieved by using sodium dodecyl benzene sulfonate (SDBS) as single surfactant. A viscosity reduction of 99% was obtained with the composited surfactant of OP-10 and SDBS at a ratio of 2:1.

    Effect of K and Ca elements on transient light hydrocarbons and oxygen-containing gases during biomass fast pyrolysis
    FENG Dongdong, ZHAO Yijun, ZHANG Yu, QIAN Juan, SUN Shaozeng
    2016, 67(7):  2970-2978.  doi:10.11949/j.issn.0438-1157.20160032
    Abstract ( 334 )   PDF (1350KB) ( 246 )  
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    K and Ca elements in the biomass are in the form of inorganic and organic matter. AAEM species affect the chain scission and depolymerization process during the biomass pyrolysis of lignin, cellulose and hemicellulose molecules. To a certain extent, it affects the formation and transformation of biomass pyrolysis gas. In the process of pyrolysis reaction, the intermediate transient product has a very important significance for the formation of final product during the pyrolysis reaction. In this paper, biomass (rice husk) was treated with acid washing, and then the directional load of K, Ca elements, respectively. By using Py-GC/MS in the pyrolysis temperature of 500—900℃, the experimental study on rapid pyrolysis of biomass was carried out. By gas chromatography mass spectrometry (GC/MS), a semi quantitative analysis was made on the types and contents of light hydrocarbons and oxygen-containing species. It explained the effect of K and Ca elements on the transient light hydrocarbons and oxygen-containing species during biomass fast pyrolysis and the formed mechanism transformation of pyrolysis gas phase. At low temperature (≤600℃), fast pyrolysis instantaneous gas products of H-form, K-loaded and Ca-loaded biomass were mainly CO, CO2 and CH4. K and Ca elements promoted the generation of CO and CO2. However, at high temperature (≥700℃), C3H6 became the main transient gas products. Ca element had a certain promotion effect on the formation of C3 (C3H6), while K element inhibited the generation of C3H6.

    Modeling of substrate degradation and methane production in anaerobic baffled reactor based on inhibition parameter of volatile fatty acids
    SHI En, LI Jianzheng, MA Tiannan
    2016, 67(7):  2979-2986.  doi:10.11949/j.issn.0438-1157.20160043
    Abstract ( 208 )   PDF (559KB) ( 258 )  
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    A 4-compartment anaerobic baffled reactor (ABR) was operated for organic wastewater treatment at a constant hydraulic retention time (HRT) of 40 h and temperature of 35°C, with the influent COD increased from 2000 to 8000 mg·L-1 stage by stage. Based on the reactor performance, Andrews model was constructed firstly for substrate degradation in the ABR. And then a prediction model for methane production was constructed by combining the stoichiometry of methane fermentation with the developed substrate degradation model. The results showed that the simulated COD of the calibrated Andrews model was well agreed with the measured data in the ABR. The experimental data were used to calibrate the dynamics parameters. k as the estimated maximum specific substrate degradation rate and Ks as the semi-saturation constant were kept at 2 d-1 and 100 mg COD·L-1, respectively, though the influent COD increased by stages. On the contrary, Ki as the inhibition parameter of volatile fatty acids (VFAs) rose following the increased influent COD. With a COD of 2000, 4000, 6000 and 8000 mg·L-1 in influent, Ki was counted for 1500, 1700, 4000 and 6000 mg COD·L-1, respectively. The equivalent COD of VFAs in the first compartment was close to or higher than the estimated Ki, indicating that a serious inhibition of VFAs to methane fermentation had occurred. Meanwhile, the equivalent COD in the last 3 compartments was lower than their Ki and showed a decreasing trend, suggesting that the inhibitory effect of VFAs on methane fermentation became weaker compartment by compartment. The methane production in the 4 compartments was ranged from 1.12—6.42, 2.54—8.96, 1.24—4.48 and 0.16—0.58 L·d-1, respectively, and the developed model could predict the measured data very well. The calibrated Andrew model and the prediction model for methane production would provide an approach to the design and operation control of ABRs.

    Startup and stability of A2N2 double sludge system denitrifying phosphorus removal process
    WANG Meixiang, ZHAO Weihua, WANG Shuying, ZHANG Yong, PENG Yongzhen, PAN Cong, HUANG Yu
    2016, 67(7):  2987-2997.  doi:10.11949/j.issn.0438-1157.20160107
    Abstract ( 339 )   PDF (1458KB) ( 334 )  
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    The A2N2-SBR (anaerobic/nitrification/anoxic/nitrification) double sludge system was investigated by using low C/N domestic sewage. This study focused on the characteristics of nitrifying bacteria biofilm membrane and denitrifying phosphorus accumulating bacteria (DPAOs) domestication and cultivation, A2N2 double sludge denitrifying phosphorus removal process denitrification and phosphorus removal characteristics of the startup process. The results showed that by connecting sludge to A2/O-SBR unit and N-SBR unit, respectively to culture domestication phosphorus accumulating bacteria sludge and nitrifying bacteria biofilms separately. By using the A2/O-SBR unit effluent as the influent of N-SBR nitrifying units, the nitrification biofilm was grown up successfully within 25 d. The ammonia nitrogen removal rate was stable above 93%. In the A2/O-SBR unit, the sludge mixture was operated under anaerobic/aerobic (A/O) condition firstly. Then, the activated sludge was conducted under anaerobic/anoxic (A/A) condition, which reinforced the effect of the inoculating sludge denitrifying phosphorus removal commendably. After 43 d, the denitrifying phosphorus accumulating bacteria (DPAOs) was successfully enriched. DPAOs accounted PAOs for 67.81%. The denitrifying phosphorus removal rate steadily stayed above 77.9%. After startup successfully, about 73%, 13% COD of raw water was used by phosphorus accumulating bacteria during the A2/O-SBR unit anaerobic phase and was removed in the N-SBR unit aeration process, respectively. The A2N2 system effluent COD, NH+4-N, PO43--P, TN concentrations was 40.6, 0, 0.4 and 13.5 mg·L-1, respectively, meeting national level A emission standards. It was suggested that A2N2 double sludge system denitrifying phosphorus removal process with good denitrification and phosphorus removal performance.

    A microbial fouling model based on Kern-Seaton model and Capdeville biofilm growth system
    XU Zhiming, SHEN Yiwen, ZHANG Yilong, LIU Zuodong, WANG Jingtao, WANG Yuhang
    2016, 67(7):  2998-3003.  doi:10.11949/j.issn.0438-1157.20151944
    Abstract ( 195 )   PDF (475KB) ( 249 )  
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    In order to study biofouling process in heat exchangers, a new microbial fouling model was established by introducing the Capdeville biofilm growth system into the Kern-Seaton model. The new model was verified by experiments of the iron bacteria growth in tubular heat exchangers. Less than 20% relative error was achieved between the model prediction and the experimental data regardless of the induction period.

    Measurement and analysis of physical properties of mixed liquid desiccants based on calcium chloride solution
    SHEN Zijing, YIN Yonggao, ZHANG Xiaosong
    2016, 67(7):  3004-3009.  doi:10.11949/j.issn.0438-1157.20160050
    Abstract ( 435 )   PDF (454KB) ( 387 )  
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    In order to improve the performance of the single desiccant solution and reduce the cost, the study of mixed liquid desiccants has been conducted by many researchers. Taking into account the low cost and weak dehumidification performance and for the sake of improving dehumidification performance of calcium chloride solution, adding lithium chloride or lithium bromide into frequently-used calcium chloride solution is considered in this paper. The solubility limit is explored by measuring the mass concentration of saturated mixed liquid of calcium chloride and lithium chloride or lithium bromide. Afterwards, the viscosity and surface tension of the mixed desiccants of lithium chloride and calcium chloride are measured. Through the experimental data of solubility, it is found that the saturated concentration of mixed liquid desiccants promotes up to 8% compared with saturated calcium chloride solution. The viscosity and surface tension of different mixing ratio of calcium chloride and lithium chloride solution show the lowest value at 1:1 mass ratio.

    Mechanism of chlorination of threonine disinfection by-product trichloroacetone in drinking water
    DING Chunsheng, ZHANG Mengqing, ZOU Bangwen, LI Naijun
    2016, 67(7):  3010-3015.  doi:10.11949/j.issn.0438-1157.20151906
    Abstract ( 300 )   PDF (598KB) ( 232 )  
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    In order to inspect the process of L-threonine chloride to TCAce and its influencing factors, a novel method using methyl tertiary butyl ether (MTBE) as extractant and 1,2-dibromopropane as internal standard for the determination of the disinfection by-products trichloroacetone (TCAce) by gas chromatography mass spectrometry(GC-MS) was described.The formation process of TCAce and its influencing factors were discussed with L- threonine as the precursor during the chloramination process.It was indicated from the formation process that the TCAce amount produced increased with the increase of pH value from 5.5 to 8.5. Under the experimental conditions, it was also shown that when the chlorine dosage increased from 5.46 to 21.84 ml, the TCAce formation amount increased. It was also shown that when the L-threonine dosage increased from 59.6 to 476.4 mg·L-1, the TCAce formation amount decreased. Temperature affected the TCAce formation from L-threonine a lot, especially in the range of 10—30℃. The TCAce formation amount increased with the increase of temperature. The formation process of TCAce chlorided by L-threonine contained substitution, oxidation reaction, amino diazotation, reduction and a series of complicated reaction.

    Characterization on PAHs distributions in pyrolysis bio-oil from different wastewater sewage sludge
    HU Yanjun, MA Wenchao, WU Yanan, CHEN Jiang
    2016, 67(7):  3016-3022.  doi:10.11949/j.issn.0438-1157.20151994
    Abstract ( 223 )   PDF (483KB) ( 247 )  
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    Distribution of sixteen kind of EPA-PAHs in pyrolysis bio-oil from four sorts of different wastewater sewage sludge was investigated. The influences of free PAHs of raw sewage sludge and phi-chemical characteristics (carbon content, H/C molar ratio, O/C molar ratio and volatile content) of the sludge on PAHs distributions were discussed. The results showed that the bio-oil produced from pyrolysis of different sludge contained sixteen kinds of EPA-PAHs in different extent. A decreasing order of content of PAHs in the different bio-oil was as followed: Industrial wastewater sewage sludge in dying (21.72 mg·kg-1) > household wastewater sewage sludge (14.10 mg·kg-1) > paper manufacturing wastewater sewage sludge (13.72 mg·kg-1) > food production wastewater sewage sludge (5.48 mg·kg-1). The PAHs of bio-oil were majorly consisted of two, three and four rings of PAHs, and their amount was accounted for more than 95% of the total concentrated PAHs. The concentration distributions of different rings of PAHs were closely related with the concentrations of the free PAHs of raw sewage sludge. In addition, it was found that the distributions of PAHs in bio-oil was also dependent of the phi-chemical characteristics of raw sludge. Along with the phi-chemical properties of sludge varied, the PAHs concentrations of three and four rings presented a similar variation trend. Their maximum contents were obtained at 30.96% of carbon content, 1.1 of H/C molar ratio, 0.33 of O/C molar ratio and 35.5% of volatile contents. The maximum content of two rings of PAHs was obtained at 20.75% of carbon content, 1.44 of H/C molar ratio, 0.6 of O/C molar ratio and 46.30% of volatile contents.

    Interaction of cellulase with surfactants and their application in detergent
    YU Yue, ZHANG Jian
    2016, 67(7):  3023-3031.  doi:10.11949/j.issn.0438-1157.20151989
    Abstract ( 500 )   PDF (2334KB) ( 494 )  
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    Effects of surfactants on cellulase activity were studied. The interaction mechanism between surfactants and cellulase was discussed by dynamic light scattering (DLS), fluorescence spectrum and ATR-FTIR. The DLS results showed that anionic surfactants were adsorbed onto cellulase surface, which made cellulase zeta potential distribute in the lower negative charge region. There was no obvious difference of cellulase zeta potential between in nonionic surfactants and deionized water. As shown in spectroscopy, the anionic surfactants had stronger influence on the main chain and side chain of cellulase than nonionic surfactant AEOs. The washing performance data of liquid detergent with and without cellulase indicated that adding cellulase into liquid detergent can enhance detergency of liquid detergent.

    Effect of calcium salt detergent on dispersity of biofuel soot
    LIU Tianxia, SONG Ruhong, LIU Yiming, XU Yufu, HU Xianguo
    2016, 67(7):  3032-3039.  doi:10.11949/j.issn.0438-1157.20160005
    Abstract ( 274 )   PDF (1481KB) ( 198 )  
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    Soot dispersity is one of the main functions of the detergent.It was investigated the influence of the three kinds of calcium salt detergents on the dispersity of the biofuel soot (BS) in liquid paraffin (LP, simulant of base stock) by means of viscosity, spot experiment, sedimentation and particle size distribution simulation method. The calcium salt detergent included higher total base number synthesis calcium sulfonate T106, alkyl calcium salicylate T109 and higher total base number sulfuration calcium alkylphenol T115B. The disperse mechanisms of calcium salt detergent to BS were investigated by means of X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. The results showed that the dispersed systems with high concentration of BS presented obvious phenomenon of shear thinning, which was similar to that of non-Newtonian fluid. Adding T109 to the LP contaminated with BS, the disperse system showed the minimal dynamic viscosity, the maximum sludge dispersion threshold, the largest drop ratio of supernatant liquid height, the minimum aggregate particle size range and the average particle size in n-heptane. T109 was the excellent additive to disperse BS in LP. The mechanisms analysis showed that the O-containing polar groups (such as carboxyl or hydroxyl) on the surface of BS were liable to adsorb calcium salt detergent through hydrogen bond or acid-base function. At the same time, the lipophilicity of non-polar chain alkane group of calcium salt detergent formed steric hindrance in the oil and impeded BS particle aggregation. Consequently, the calcium salt detergent can disperse the BS particle in the oil.

    Service stress optimization of injection-molded engineering plastic product
    WANG Xinyu, LI Zheng, GU Junfeng, RUAN Shilun, SHEN Changyu, WANG Xicheng
    2016, 67(7):  3040-3046.  doi:10.11949/j.issn.0438-1157.20151843
    Abstract ( 284 )   PDF (2219KB) ( 346 )  
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    Recently, engineering polymer material is applied widely in aerospace and automotive fields. Engineering plastic products manufactured by injection molding have to endure mechanical, thermal and other complicated service conditions when they work. Under the complicated load conditions, the magnitude of service stress in engineering plastic parts is associated with the structure safety of the engineering devices, especially with people's lives. Taking warpage and residual stress of a hemisphere polycarbonate product as the initial conditions of the mechanical analysis, this paper proposes an efficient service stress optimization strategy with respect to the process parameters and the structure of the product and cooling channel, which integrals injection molding analysis and mechanical analysis. The maximum service stress is finally reduced by using an optimization strategy based on Kriging surrogate model and EI method. The results indicate that the thickness of the product, melt temperature and packing pressure are critical factors to influence the service stress.

    Thermal convection calculation with variable time step in Hele-Shaw flow simulation of injection molding
    WANG Chaofang, HUANG Ming, SHI Xianzhang, SHEN Changyu, ZHAO Zhenfeng
    2016, 67(7):  3047-3054.  doi:10.11949/j.issn.0438-1157.20151900
    Abstract ( 310 )   PDF (19383KB) ( 139 )  
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    In Hele-Shaw flow simulation, the directly solved variable is pressure and the velocity is only the post-treating result of pressure. Around the injection gate, the velocity may be very high along with reducing elemental size. This means that when the energy conservation equation is solved as a whole, the time step must be very short, otherwise, the error in the heat convection is unavoidable. The above problem can be overcome by using the operator-splitting method, in which the material at the current computing points needs to be tracked back to its position in the last time-step. However, this may lead to a new difficulty. If the elemental velocity is very high, the tracking needs to pass through a few elements and the reversetracking may fail. To solve the problem, a new algorithm named sub time step with variable size was suggested to deal with the thermalconvection in this paper, in which the sub time step using dichotomy was introduced that bounded the tracking path in a certain element. The new algorithm made the computation more simple and effective. The numerical examples showed that the new method had same accuracy as one using uniform small time step and high solving stability, but calculating time was dramatically reduced.

    Preparation and performance characteristic of MAPP flame-retardant EVA foamed composites
    LIAN Hanqing, ZHENG Yuying, QIU Hongfeng
    2016, 67(7):  3055-3062.  doi:10.11949/j.issn.0438-1157.20151597
    Abstract ( 234 )   PDF (2158KB) ( 438 )  
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    The MAPP, as a derivative of ammonium polyphosphate (APP), was synthesized via a grafting reaction between APP and ethylenediamine (EDA). The intumescent flame-retardant was fabricated by the mixture of MAPP, EG, and WF, and introduced into the EVA matrix for the preparation of flame-retardant EVA foamed composites. The FT-IR, XRD, 1H NMR, LOI, UL-94, CONE, SEM, TG, and electronic universal testing machine were applied to appraise the grafting degree, flame-retardant, and mechanical performance of the as-obtained composites, respectively. The results showed that the EDA has been successfully grafted on APP, and the as-prepared MAPP could not only possess desirable flame-retardant performance, water-resistance, as well as a better compatibility with EVA matrix, but also decrease the heat release. It is worth noting that foamed composite obtained the optimum comprehensive properties when the MAPP loading was 20%, and exhibited 28.8% (LOI), V-0 (UL-94), 1.282 MPa (tensile strength), and 326. 40% (elongation), respectively.

    Change in microstructures of hard elastic HDPE cast film during cold-stretching process
    SHEN Peng, LI Juan, YANG Xingcheng, LIU Jingru, YU Qiang
    2016, 67(7):  3063-3070.  doi:10.11949/j.issn.0438-1157.20151398
    Abstract ( 255 )   PDF (4502KB) ( 235 )  
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    The hard elastic high density polyethylene(HDPE)cast film was cold-stretched uniaxially with different stretching ratios and rates in a process of preparing HDPE microporous membranes. AFM, FE-SEM and WAXD were used to observe the variations in the lamellar structure during the cold-stretching processes, and the microporous structure of resulting microporous membranes was evaluated with measurements of porosity and permeability. It was found that increasing cold-stretching ratio could promote the separation of row-nucleated lamellar structure in the films, and be beneficial to the increase of porosity and permeability in the microporous membranes. However, over high cold-stretching ratio led to the collapse of the lamellae, destroying the microporous structure. With the increase of stretching rates, the lamellae was separated to a greater extent, resulting in generation of more micropores and more uniform distribution. During the cold-stretching, the broken micro-second crystals at the lamellae edge and the crystallized long tie chains between lamellae converted to bridges connecting separated lamellae.

    Preparation of niobium pentoxide loaded on porous carbon and its application in supercapacitors
    LI Heshun, GAO Lixin, ZHANG Daquan, LIN Tong
    2016, 67(7):  3071-3077.  doi:10.11949/j.issn.0438-1157.20151500
    Abstract ( 311 )   PDF (1122KB) ( 443 )  
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    Niobium pentoxide (Nb2O5) loaded on porous carbon was synthesized from resorcinol, formaldehyde and niobium oxalate hydrate based on in-situ polymerization and high-temperature calcination. X-ray diffraction (XRD) and scanning electron microscope (SEM) examinations showed that the orthorhombic type Nb2O5 was synthesized and loaded on porous carbon with protrusion on its surface. Cyclic voltammetry (CV) tests indicated that the specific capacitance of the composites was 290 F·g-1 (1.0~3.0 V vs. Li+/Li) with a good large-current discharge capability evidenced by the capacitance of 108 F·g-1 at a large-current of 5 A·g-1. The initial capacitance was 355 F·g-1 at 0.5 A·g-1 with 82% capacitance being maintained after 100 cycles. The pseudocapacitance characteristics of the complex was studied by analyzing the electrochemical impedance spectroscopy (EIS) and simulation of equivalent circuit. The improved conductivity and pseudocapacitance of Nb2O5 were due to several factors including the shortened distance in the composites and the reduced diffusion resistance of the Li+ in the electrolyte during the charge-discharge process and the enhanced contact with the electrolyte because of the protrusion morphology.

    Strengthen preparation of high purity heavy manganese carbonate in ammonia buffer system
    CHEN Nanxiong, XIE Luosheng, SHU Jiancheng, LI Huacheng, WANG Chunfei, LIU Zuohua
    2016, 67(7):  3078-3083.  doi:10.11949/j.issn.0438-1157.20151048
    Abstract ( 359 )   PDF (1437KB) ( 341 )  
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    High purity and heavy manganese carbonate was prepared via controlling crystallization in ammonia buffer system, with sodium carbonate and high purity manganese sulfate as the starting materials. When the concentration of MnSO4 and Na2CO3 solution was 1.5 mol·L-1, and Na2CO3 excess coefficient was 110% with adding rate of 120 ml·h-1 at pH 8.5 and 50℃, the apparent density of manganese carbonate was 1.67 g·cm-3 and tap density was 2.15 g·cm-3. Ammonia buffer system increased the stability of the solution, and suppressed the formation of manganese hydroxide and partial manganese hydroxide. The morphology of high density of manganese carbonate was spherical, and particle size with an average size (D50) of 30.32 μm distributed uniformly. Heating the manganese carbonate prepared in this study, the apparent density and tap density of obtained mangano-manganic oxide was 1.09 g·cm-3 and 2.18 g·cm-3, respectively.

    Quantitative risk assessment in storage tank areas based on event-chains
    ZHAO Jinlong, HUANG Hong, LI Cong, WANG Jianjun
    2016, 67(7):  3084-3090.  doi:10.11949/j.issn.0438-1157.20151908
    Abstract ( 317 )   PDF (714KB) ( 260 )  
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    Large storage tank areas are easily involved into severe accidents because of event-chains. According to the accidental escalation's law of tank accidents, the quantitative risk assessment method based on event-chains is developed. In the method, the individual risk (IR) and societal risk (SR) are calculated based on the practical accident scenarios that may occur because of event-chains. Moreover, the principals of individual risk are introduced to determine the effective scenarios, and thus many practical scenarios will be cut down. In the paper, the lightning event chain of tank areas is taken as an example. From the result, it can conclude that some common scenarios that have obvious effects are neglected and the calculated results are conservative by using the traditional method. Moreover, the planning areas enlarge obviously as the event chains are considered. Therefore, it is essential to consider the event chain especially for big tank areas.

    Quantitative safety early warning method of fault propagation for petrochemical plants
    HU Jinqiu, ZHANG Laibin, WANG Anqi
    2016, 67(7):  3091-3100.  doi:10.11949/j.issn.0438-1157.20151774
    Abstract ( 231 )   PDF (559KB) ( 267 )  
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    In the petroleum system, process fault and its damage caused by the fault propagation chains have a serious effect on the oil and gas production and people's life. In this paper, from the fault causal chain perspective, a quantitative safety early warning method of fault propagation is proposed. First, the fault propagation chains is analyzed, and the GTST-DMLD (goal tree success tree, GTST; dynamic master logic diagram, DMLD) model is developed, by which the chain effect of the fault propagation behavior can be quantitatively modeled. It can be further used to evaluate the system safety state when the abnormal event happens. Based on the results of GTST-DMLD model, Markov process theory is introduced to establish a fault prognosis model, by which the fault consequence and its propagation direction can be predicted timely. The results given by the proposed method can help field operation personnel to carry out pre-active maintenance or emergency disposal. In the case study, the proposed method is applied to the atmospheric distillation unit and the vacuum furnace in a certain petrochemical company. It has been fully validated and provides a great help for the risk reduction and accident prevention in the field.

    Suppression effect of CO2-twin fluid water mist on methane/air explosion in vented duct
    PEI Bei, YU Minggao, CHEN Liwei, YANG Yong, NIU Pan, ZHU Xinna
    2016, 67(7):  3101-3108.  doi:10.11949/j.issn.0438-1157.20151388
    Abstract ( 302 )   PDF (1157KB) ( 457 )  
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    The experimental study on the synergistic suppression effect of carbon dioxide and ultrafine water mist on stoichiometric premixed methane/air mixture in a vented duct was carried out in this paper. The ultrafine water mist was generated from a twin fluid nozzle. The results indicated that CO2 and water mist had a synergistic suppression effect on methane/air explosion and the efficiency of explosion suppression was significantly improved. With the increase of mist spraying time, the peak flame propagation speed and peak overpressure decreased obviously. When the pressure of CO2 increased to 0.4 MPa and mist spraying time was more than 3 s, the methane/air mixture cannot be detonated after several times of ignition. It was beneficial to improve the explosion suppression efficiency of water mist.

    Prediction of auto-ignition temperatures for binary liquid mixtures based on electro-topological state indices
    HE Fan, JIANG Juncheng, PAN Yong, NI Lei
    2016, 67(7):  3109-3117.  doi:10.11949/j.issn.0438-1157.20151811
    Abstract ( 243 )   PDF (752KB) ( 198 )  
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    The auto-ignition temperature (AIT) values of 168 sets of binary flammable liquid mixtures composed of different components and volume ratios were measured by AITTA 551 auto-ignition temperature tester. The mixed electro-topological state indices (ETSI) values of different atom types were calculated. The modified particle swarm optimization (MPSO) algorithm with exponential decreasing inertia weight (EDIW) was applied to optimize the support vector machine (SVM) hyper-parameters and MPSO-SVM prediction model was established. The model was employed in research for predicting the AIT of mixtures according to the mixed ETSI values of different atom types. The results showed that it could effectively predict the AIT of binary liquid mixtures based on electro-topological state indices. The squared correlation coefficient (R2) and average absolute error (AAE) of MPSO-SVM model were 0.991 and 3.962 K, respectively. In terms of model generalization performance and prediction accuracy, the result of MPSO-SVM model was obviously superior to the results of multiple linear regression (MLR), grid search method (GSM-SVM), genetic algorithm (GA-SVM) and particle swarm optimization (PSO-SVM). This study provided an effective method to predict the AIT of binary liquid mixtures for engineering.