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Table of Content
05 July 2009, Volume 60 Issue 7
    Heat transfer enhancement of free surface MHD-flow by protrusion wall
    LI Bo, HUANG Hulin
    2009, 60(7):  1609-1616. 
    Abstract ( 922 )   PDF (5768KB) ( 344 )  
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    Due to the magnetohydrodynamic (MHD) effect depressing heat transfer coefficients by pulsation suppression of external magnetic field on the electrical conducting fluid flow in many applications, the hemispherical protrusion wall was employed to free surface MHD-flow system as a heat transfer enhancement, because of its excellent characteristics, including high heat transfer coefficients, low friction factors and high overall thermal performance.The heat transfer characteristics of the free surface MHD-flow with hemispherical protrusion wall were simulated numerically by using the magnetic induction method and the modified turbulent equations, which were solved by the scalar transport equation solver.The results showed that in the range of Hartmann number 30—70, the protrusion wall assemblies could achieve heat transfer enhancement by about 1.3—2.3 relative to the smooth channel, with friction loss increase by about 1.34—1.45.Thus higher Nusselt number could be obtained by the protrusion wall with a smaller friction loss increase, resulting in much higher overall thermal performance.

    传递现象

    Forecasting fouling characteristics of plain tube based on least squares-support vector machine for regression

    XU Zhiming;WEN Xiaoqiang;SUN Yuanyuan;SUN Lingfang
    2009, 60(7):  1617-1622. 
    Abstract ( 1014 )   PDF (1520KB) ( 290 )  
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    A fouling test system was set up and the least squares-support vector machine for regression (LS-SVMR)was built to predict the fouling characteristics of the plain tube,with input vectors of tube wall temperature, inlet and outlet temperatures and output vector of fouling resistance.The model was proved to be reasonable and feasible by comparing predictions and measurement results.The results showed that the model is applicable not only to the conditions that water flow, ambient temperature, and material parameters are constant, but also to the conditions when they change.

    Kinematic characteristics and thermophoretic deposition of inhalable particles in temperature gradient field
    LIU Ruolei, YANG Ruichang, YOU Changfu, ZHAO Lei, ZHOU Tao
    2009, 60(7):  1623-1628. 
    Abstract ( 906 )   PDF (4387KB) ( 650 )  
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    The kinematic characteristics and thermophoretic deposition of inhalable particles(PM2.5)suspended in air flow in a vertical rectangular duct with temperature distribution were experimentally studied.Particle dynamics analyzer(PDA)was used for the on-line measurement of particle motion and particle concentration distribution in the cross-sections of the duct.Influence of the parameters such as the ratio of the bulk air temperature to the cold wall temperature in the duct on the kinematic characteristics and the deposition efficiencies of PM2.5 was investigated.Experimental results indicate that the particle concentration distribution in the duct,extremely in the area near the walls,is mainly determined by the turbulent diffusion in the flow,but turbulent diffusion is hard to make particles to deposit on the dust walls. Thermophoresis is the key factor to the particle deposition on the cold duct walls.Based on the experimental results,an empirical correlation for the calculation of thermophoretic deposition efficiency of PM2.5 is developed.The empirical correlation agrees reasonably well with the experimental data.

    多相流和计算流体力学

    Electrostatic potential in gas-solids fluidized beds influenced by injection of charge inducing agents

    XU Yi;WANG Jingdai;YANG Yongrong

    2009, 60(7):  1629-1637. 
    Abstract ( 690 )   PDF (8443KB) ( 270 )  
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    Accumulation of electrostatic charges in gas-solids fluidized beds can lead to particle adhesions, electrostatic discharges, wall sheeting and even explosion, so it is of vital importance to reduce the electrostatic level in industrial fluidized beds.A δU-χi theory was proposed for the LLDPE-N2 system.The electronegativity χi of the metal ion was assumed to play an important role in determining the polarity of the LLDPE particles, and the change of the electrostatic potential was in negative correlation to the electronegativity of the metal ion after contact and separation of the particles and LLDPE.The charge inducing agent included the positive charge inducing agent, negative charge inducing agent and the inactive liquid charge inducing agent.The experiments in gas-solids fluidized bed with the introduction of three kinds of charge inducing agent were designed and carried out.It was found that the addition of negative charge inducing agent increased the electrostatic level obviously, the addition of a small amount of positive charge inducing agent decreased visibly the electrostatic level, and the addition of inactive liquid charge inducing agent reduced the electrostatic level significantly in the fluidized bed.The results agreed well with the prediction according to the theory proposed, which would be helpful to choosing charge inducing agent in industrial application.

    CFD study on cavitation of liquid oxygen in Venturi

    ZHANG Xiaobin;CAO Xiaoli;QIU Limin;GAN Zhihua;ZHANG Xuejun

    2009, 60(7):  1638-1643. 
    Abstract ( 1128 )   PDF (5184KB) ( 656 )  
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    To accurately control the flow rate of liquid hydrogen and oxygen in liquid-fuel rocket engine,Venturi is commonly used.A CFD study on cavitation of liquid oxygen in Venturi was conducted,taking into consideration the thermal effect on the assumption about liquid-vapor thermal balance.The numerical model comprised homogeneous multiphase model on the basis of Reynolds-averaged Navier-Stokes equations and the full cavitation model.Computational results about the pressure and temperature distributions along the cavitating hydrofoil were then compared to the experimental data of NASA to validate the model.Detailed analysis on cavitation characteristics included the pressure,temperature and cavitation intensity profile along the hydrofoil wall,the impact of inlet-outlet pressure ratio on cavitation and the mechanism of maintaining cavitation in cryogenic fluids.The numerical results of this paper can be used to guide liquid-oxygen-Venturi design.

    Properties of water vapor supersaturation under spray scrubbing conditions

    FAN Fengxian;YANG Linjun;YUAN Zhulin
    2009, 60(7):  1644-1650. 
    Abstract ( 894 )   PDF (658KB) ( 486 )  
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    In order to achieve growth of PM2.5 fine particles by water vapor condensation using a flue gas desulfurization (FGD) spray scrubber, it is necessary to create a supersaturated water vapor atmosphere in the scrubber.Based on this, heat and mass transfer models between gas and liquid phase under spray scrubbing conditions were established, and the influences of operation parameters on water vapor supersaturation were investigated.The results showed that supersaturated water vapor atmosphere can be produced by lowering the spray liquid temperature, increasing the moisture content of the flue gas, as well as adding steam in the top of the scrubber above the spray liquid inlet.A higher liquid-to-gas ratio and smaller spray droplets favored the formation of supersaturated water vapor atmosphere.The measures for creating a suitable degree of water vapor supersaturation through changing the operation parameters were obtained.The research results are helpful to guiding practical design and operation of the desulfurization and dust removal process.

    Oil holdup modeling of oil-water two-phase flow using thermal method based on LSSVM and GA

    ZHANG Chunxiao;ZHANG Tao

    2009, 60(7):  1651-1655. 
    Abstract ( 874 )   PDF (435KB) ( 467 )  
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    Oil holdup of oil-water two-phase flow was measured by using platinum resistance based on the fluid thermal balance equation.In order to improve the measurement accuracy of oil holdup, the effects of the electrical heater fore-and-aft temperature difference of platinum resistance and total oil-water flux on oil holdup were researched.A least squares support vector machine(LSSVM)model with parameters optimized by genetic algorithm(GA)was proposed, the temperature difference and total flux of oil-water two-phase flow were used as inputs, and the oil holdup was used as output of the LSSVM model and the ideal model of oil holdups was obtained.The oil holdup model based on least squares support vector machine and genetic algorithm (LSSVM-GA) was compared with the theory corrected model and good oil holdup measurement results were obtained.The average measurement error was 0.96% in the range of 5% to 60% oil holdup.

    Slug velocity of severe slugging in pipeline-riser system

    LUO Xiaoming;HE Limin;MA Huawei

    2009, 60(7):  1656-1660. 
    Abstract ( 694 )   PDF (955KB) ( 341 )  
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    During the exploitation of offshore oil,it is easy to form severe slugging in the riser system at a low gas-liquid velocity.The magnitude of the pressure fluctuation can be significantly high,causing dramatic change of flow rate and leading to other damages.In this paper,the characteristics of slug velocity during the four stages of severe slugging in the pipeline-riser system were studied.It was found that the slug head rose in the riser at a constant velocity in the slug formation stage.At the same time,the direction of slug tail movement was opposite to the flow direction,and the tail velocity kept constant when flowing through the inclined pipe.In the process of blowout,the liquid velocity in the pipeline-riser system increased and reached a maximum value when the slug tail reached the top of the pipeline-riser.At this moment,the instantaneous flow rate was much larger than that in the slug production stage.

    Low-temperature catalytic steam reforming of phenol for hydrogen production
    XIANG Yizhi, KONG Lingniao, LU Chunshan, MA Lei, ZHANG Qunfeng, LI Xiaonian
    2009, 60(7):  1661-1667. 
    Abstract ( 813 )   PDF (673KB) ( 313 )  
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    The catalytic steam reforming of phenol for hydrogen production was realized under mild conditions (523-723 K) over a Raney Ni catalyst.The conversion of phenol and selectivity of H2 were highly dependent upon the reaction conditions, such as temperature, liquid hourly space velocity (LHSV), and phenol concentrations.A higher temperature and lower LHSV could increase the conversions of phenol, but decrease the selectivity of H2.When compared with the aqueous-phase reforming of phenol for hydrogen, however, a higher reaction temperature and the vaporization of the liquid solution are generally required for the steam reforming process, but it shows a significantly higher H2 selectivity (93%-100%) than the aqueous-phase reforming.Additionally, the steam reforming of phenol over the Raney Ni catalyst was carried out under milder conditions than those reported in literatures, meanwhile, the Raney Ni catalyst was quite stable (60 h) for the phenol steam reforming process, and the content of CO in the gas effluent was quite low (molar ratio of CO/CO2 was 0.01—0.2).Therefore, H2 produced can be used as hydrogen source directly.

    Effect of Co on selective hydrogenation of cinnamaldehyde to cinnamyl alcohol over Pt/CNTs catalyst
    YU Tieming, LI Yan, XU Xiaoling, ZHOU Renxian
    2009, 60(7):  1668-1672. 
    Abstract ( 663 )   PDF (998KB) ( 224 )  
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    The Pt-Co catalysts supported on carbon nanotubes (CNTs) were prepared by wet impregnation and used for the selective hydrogenation of cinnamaldehyde (CMA) to the corresponding cinnamyl alcohol (CMO).The results showed that the addition of Co could improve the catalytic activity and selectivity for C=O bond.The Pt-0.17%(mass) Co/CNTs catalyst exhibited the best hydrogenation activity of 97.1% conversion and selectivity for C=O bond of 93.6 % to cinnamyl alcohol (CMO) at 70℃ under 2.0 MPa H2 pressure with the reaction time of 1.5 h. The study of hydrogenation kinetics of CMA over Pt-0.17%(mass)Co/CNTs catalyst indicated that the activation energy of hydrogenation of cinnamaldehyde was 26.5 kJ•mol-1.

    Tetrahydrofuran polymerization catalyzed by organic-inorganic hybrid clay
    WANG Pengfei, JIA Zhiqi, ZHAO Min, SUN Zijin, ZHANG Hongbo, JI Shengfu, ZHAO Yongxiang
    2009, 60(7):  1673-1679. 
    Abstract ( 789 )   PDF (872KB) ( 346 )  
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    A kind of solid acid catalyst containing alkyl sulfonic acid group was prepared by post-synthesis grafting of 3-mercaptopropyltriethoxysilane (MPTES) to the surface of acid-modified clay.The clay samples were characterized by means of XRD, N2 adsorption-desorption, FTIR, IR analysis of adsorbed pyridine and acid-base titration.The results showed that the hybrid material maintained the mesoporous structure with pore size mainly distributed in 3-4.3 nm, and the acid amount increased by 35%.In the polymerization of tetrahydrofuran, the organic-inorganic hybrid clay catalyst showed good catalytic performance.When the temperature was 35℃ and the reaction time was 8 h, the yield of polymer reached 30% and the number-average molecular weight was about 2000.

    Degradation of high concentration nitrobenzene using hydrophobic nano-CuO/TiO2 under visible light
    JI Fangying, XU Xuan, FAN Zihong
    2009, 60(7):  1680-1686. 
    Abstract ( 750 )   PDF (975KB) ( 614 )  
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    Hydrophobic CuO/TiO2 was prepared from nano-CuO/TiO2 and sodium dodecyl sulfate(SDS).The influences on photocatalytic degradation of nitrobenzene using these catalysts under visible light irradiation were investigated.Characterization of the catalyst showed that SDS-CuO/TiO2 photocatalysts had complete diffraction peaks of anatase and CuO crystalloids,its UV-Vis absorption performances had nothing to do with the variations of SDS loadings,and hydrophobic sites on the catalysts surfaces were mostly long chain alkyls.Experiments indicated six factors having influence on the degradation of nitrobenzene and their best levels were determined respectively.SDS loading was 2.3 g•(2.5 g TiO2)-1.Initial concentration of nitrobenzene ranged from 400—500 mg•L-1.Dosage of catalysts and H2O2 were 0.2 g•L-1 and 6 ml•L-1,respectively.pH was 9.Under these conditions,nitrobenzene degradation ratio was about 80% after irradiation for 2 h and 93% for 4 h.

    催化、动力学与反应器

    Kinetics and mechanism of ZnOOH catalyzed ozonation of trace p-chloronitrobenzene in water

    XU Zhenzhen;CHEN Zhonglin; BEN Yue;QI Fei;SHEN Jimin
    2009, 60(7):  1687-1692. 
    Abstract ( 799 )   PDF (761KB) ( 446 )  
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    Zinc oxyhydroxide (ZnOOH) prepared in laboratory was used as catalyst to determine rate constants of the catalyzed ozone decomposition and the catalytic ozonation of p-chloronitrobenzene (p-CNB) in water.The mechanism of catalytic ozone decomposition was discussed and then determined by electron spin resonance (ESR) test.The effect of solution pH on the catalytic activity of zinc oxyhydroxide was investigated.The results showed that the first-order rate of ozone decomposition increased by 1.87 times in the presence of zinc oxyhydroxide.At the reaction time of 20 min, the p-CNB removal efficiency of ZnOOH/O3 was about 96.1%, one time more than that of O3.An enhancement of hydroxyl free radicals was obtained in the ZnOOH catalyzed ozone decomposition.The addition of radical inhibitor, such as t-butanol, significantly depressed the rate constant of catalytic ozonation of p-CNB, by at least 10 times.No correlation was found between surface hydroxyl groups and the activity of catalytic ozonation of p-CNB.The state of surface charge has some relation with the catalytic activity of ZnOOH, as the nearly zero charged surface (the solution pH was close to pHpzc) was favorable for the catalytic ozonation of p-CNB.

    Preparation and photocatalytic bactericidal activity of silver loaded TiO2 thin films

    WU Donghai;YOU Hong;LIU Weiwei;DU Jiaxuan;JIN Darui

    2009, 60(7):  1693-1699. 
    Abstract ( 720 )   PDF (2197KB) ( 358 )  
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    Photocatalytic nano-porous titanium dioxide films were prepared by the anodic oxidation method in sulfuric acid solution,and were loaded with silver by the photodeposition method.The microstructure and grain morphology in the films were characterized by SEM and XRD.The effect of anodizing parameters(anodizing voltage,current density and electrolyte concentration)on the photocatalytic bactericidal activity of TiO2 films was investigated.It showed that the titanium oxide film was mainly composed of anatase and rutile TiO2.With increasing anodizing voltage,the content of rutile TiO2 increased,and the average diameters of nano-holes was enlarged.When the current density was 150 mA•cm-2,the voltage increased from 120 V to 180 V,the content of rutile TiO2 increased from 19% to 96%,the average diameters of nano-holes increased from 93 nm to 283 nm.A proper increase of current density and a suitable Ag loading could enhanced the photocatalytic activity of TiO2 film.When prepared at 140 V/150 mA•cm-2 in 1 mol•L-1 sulfuric acid solution,and loaded with silver in 3 g•L-1 silver nitrate solution,the Ag-TiO2 film had the best photocatalytic bactericidal activity.The results suggested that photocatalytic bactericidal treatment with Ag-TiO2 thin film has the potential for use as a new tool for water treatment.

    Kinetic simulation of gas explosion and inhibition mechanism in enclosed space
    LIANG Yuntao, ZENG Wen
    2009, 60(7):  1700-1706. 
    Abstract ( 861 )   PDF (8047KB) ( 213 )  
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    Through amending the SENKIN code of CHEMKIN Ⅲ chemical kinetics package, the computational model of gas explosion in a constant volume bomb was built, and the detailed reaction mechanisms (including 53 species, 325 reactions) were adopted.The trends of variation of the mole fractions of reactants, activation centers in the explosion process, and the mole fractions of catastrophic gases after explosion were analyzed by using this model.Furthermore, through the sensitivity analysis of the reaction mechanisms of gas explosion, the key reactions that affected gas explosion and formation of catastrophic gases were identified.At the same time, the inhibition mechanism of H2O on gas explosion and formation of catastrophic gases were analyzed.The results showed that the temperature and pressure were 2700 K and 0.22 MPa respectively after gas explosion when the mixed gas had no water.When the mole fraction of water in the mixed gas was 10%, the temperature and pressure were 2580 K and 0.21 MPa respectively.When the mole fraction of water in the mixed gas was 15%, the temperature and pressure decreased by 180 K and 0.025 MPa respectively against the case that the mixed gas had no water.Furthermore, the water in the mixed gas would inhibit gas explosion and the formations of CO, CO2 and NO2.

    催化、动力学与反应器

    Experimental study on mechanism of lowering ignition temperature of anthracite combustion catalyzed by Fe2O3

    GONG Xuzhong;GUO Zhancheng;WANG Zhi
    2009, 60(7):  1707-1713. 
    Abstract ( 836 )   PDF (4288KB) ( 266 )  
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    TG-DTG and DTA determination indicated that ignition temperature of anthracite was lowered from 458℃ to 405℃ by addition of 10% catalyst Fe2O3.Based on the nature of anthracite ignition temperature, pyrolysis conversion and pyrolysis gas composition during the catalytic combustion were examined.The results showed that with Fe2O3 addition anthracite pyrolysis conversion was 3.0% at 405℃ and components with higher heating value increased in the pyrolysis gas. However, without Fe2O3 addition pyrolysis conversion was 1.8% at ignition temperature.It could be concluded that the heat from the homogeneous combustion of catalytic combustion was higher than that of non-catalytic combustion.TG-DTG indicated combustion conversion of 10 % at ignition.SEM images of chars indicated rough surface of char with plenty of small pores.BET of char from catalytic combustion was 170 m2•g-1 while BET of char from non-catalytic combustion was only 128 m2•g-1, which could be the main reason for lowering ignition temperature.The results from oxygen adsorption experiment showed increased oxygen content of coal with catalyst addition, which caused faster oxygen adsorption at a lower temperature and shortened the time to get required oxygen concentration and heat accumulation for ignition, thus the ignition temperature was lowered.

    Preparation of bromine-containing copper-organic coordination compound and its catalytic performance in oxidative carbonylation of methanol

    LIU Dinghua;JIANG Zhiyang;LIU Xiaoqin;ZHONG Qin

    2009, 60(7):  1714-1718. 
    Abstract ( 822 )   PDF (1579KB) ( 222 )  
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    A bromine-containing copper-organic coordination compound was prepared by the reaction of tetrrpropylammonium bromide with copper bromide in ethyl acetate solution.The compound obtained was characterized with FTIR, XRD, ICP-AES and EA.Meanwhile, its catalytic performance for the oxidative carbonylation of methanol was investigated.The results showed that the introduction of ligand could change the density of copper electron cloud, which improved the redox property for the oxidative carbonylation of methanol to prepare dimethyl carbonate.In the presence of strong base and weak acid salts, the per pass conversion of methanol could reach 57% under the reaction conditions of temperature 383 K, pressure 3.5 MPa, and the mass concentration of catalyst in methanol 0.20 g•ml-1.

    分离工程

    Theoretical calculations of electrostatic force between ellipsoidal drops in W/O emulsion

    GONG Haifeng;SONG Shiyuan;PENG Ye
    2009, 60(7):  1719-1724. 
    Abstract ( 713 )   PDF (1521KB) ( 443 )  
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    At the present time, there is no good means for calculating electrostatic force between two ellipsoidal drops in the process of electro-demulsification.In this paper, a “two-molecule” model of ellipsoidal drop was established.And then the ellipsoid situation was transformed into sphere situation by coordinate transformation.By utilizing bipolar coordinates and Maxwell stress tensor, the expression of electrostatic radial and tangential forces between two drops was deduced.The numerical calculation results showed that when the space between drops was large, electrostatic forces calculated by the model agreed well with those by the dipole model, and critical angle of attraction- repulsion, after being modified, was in good agreement with Eow’s test result.When the space between drops was small, the model was applicable to calculating electrostatic forces and critical angle between drops,and the calculating numerical values were larger than those obtained on condition that the space between drops was large, it could indicate clearly that the space between drops had a great influence on distribution of polarization charges on drops surface.

    Theoretical analysis of H2/HD/HT separation performance by electrolysis-distillation process

    XIA Xiulong

    2009, 60(7):  1725-1729. 
    Abstract ( 572 )   PDF (3433KB) ( 850 )  
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    A theoretical model was built to study the separation of hydrogen isotopes by the electrolysis-distillation process, and the separation performance of H2/HD/HT was investigated.Enrichment behavior of both electrolysis and distillation was obtained: HDO and HTO concentration in electrolysis reached 8.35×10-4 and 6.34×10-6 respectively; HD and HT concentration in reboiler finally reached 0.033 and 6.06×10-5 respectively.For the difference of separation factor for H/D and H/T, about 63.4% HTO stay in electrolysis cell which brought a poorer HT enrichment in reboiler compared with that of HD.As enrichment developed, deuterium(tritium) extraction efficiency decreased with time.

    A robust MPC technique with adaptive disturbance model
    HAN Kai, ZHAO Jun, ZHU Yucai, XU Zuhua, QIAN Jixin
    2009, 60(7):  1730-1738. 
    Abstract ( 737 )   PDF (3863KB) ( 1322 )  
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    A robust model predictive control(RAMPC)technique with an adaptive disturbance model is developed.The dynamics of unmeasured disturbances are modeled by ARMA model.In order to get accurate identification and faster convergence,a multi-iteration pseudo-linear regression(MIPLR)method is proposed.In addition,the optimization in MPC is formulated as a min-max problem,in which the data uncertainties have been taken into account.For lower computational burden,the min-max problem is reduced to a nonlinear min one,and is solved by multi-step linearization method.Numerical simulations have been demonstrated the effectiveness of the proposed methods.

    M-estimator based support vector machine and its application
    BAO Xin, DAI Liankui
    2009, 60(7):  1739-1745. 
    Abstract ( 768 )   PDF (1333KB) ( 346 )  
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    Validity of training samples is important to regression model, however, outliers in training sample sets are hard to avoid, which will disturb the model accuracy.In order to overcome the influence of outliers to regression model, a new M-estimator based support vector machine (M-SVM) was introduced. It replaced the sum of square residuals in least squares support vector machine (LS-SVM) with objective function of M-estimator.An iterative modeling algorithm of the M-SVM was proposed.The M-SVM was used in a low-dimension data regression problem with outliers and in the NIR spectral analysis of gasoline research octane number.Experimental results showed that the M-SVM was more robust and accurate than other SVMs.

    过程系统工程

    Optimization control of ball mill load in blending process with data fusion and case-based reasoning

    BAI Rui;CHAI Tianyou
    2009, 60(7):  1746-1752. 
    Abstract ( 648 )   PDF (723KB) ( 501 )  
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    Ball mill is used widely in various productions, such as chemical industry, metallurgical industry and power industry.Ball mill is high energy consumption equipment, whose load is the key index that affects the production efficiency and energy consumption.In the blending process of sintering alumina production, raw materials are fed into the ball mill and blended to form the raw slurry.In order to make ball mill work at the optimal load state, a control strategy of the ball mill load in the blending process was proposed with data fusion and case-based reasoning.Current and vibration were used to estimate the state of ball mill load with data fusion technology, and ball mill load was controlled to achieve the optimal state with case-based reasoning.Industrial experiment in an alumina factory showed the validity of the proposed control strategy.

    Direct electrochemical reduction of Sulfur Black 2BR 200% on silver-plated graphite electrodes
    MA Chun’an, ZHU Zhangen, XU Yinghua, CHU Youqun, ZHOU Yaming, GONG Jinxing
    2009, 60(7):  1753-1757. 
    Abstract ( 731 )   PDF (660KB) ( 422 )  
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    Silver-plated graphite electrodes were prepared by the absorption method and its surface structure was characterized by SEM assembled with energy dispersive spectrometer.The electrochemical behavior of Sulfur Black 2BR 200% on graphite and silver-plated graphite was studied with linear sweep voltammograms.Experimental results showed that metal silver was successfully coated on the surface of graphite and silver-plated graphite electrode gave higher current and showed better catalytic property for the reduction of Sulfur Black 2BR 200%.In addition, the rate of reduction reaction of Sulfur Black increased with increasing pH of electrolyte.The electrolysis experiments were performed by using graphite and silver-plated graphite cathodes respectively.Excellent current efficiency (92.2%) was obtained in the following reaction condition: silver-plated graphite used as cathode,temperature(27±2)℃, current density 6.25 mA•cm-2,pH of electrolyte 14.

    Identification of a shortcut denitrifying phosphorus removing bacterial strain and its biological utilization
    LIU Hui, SUN Yanfu, CUI Yingde, ZHOU Kangqun, GU Xueting, CHEN Yiping
    2009, 60(7):  1758-1766. 
    Abstract ( 776 )   PDF (1308KB) ( 346 )  
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    The study was based on the principle of shortcut denitrifying phosphorus removal.In order to enrich shortcut denitrifying phosphorus removing bacteria (SDPB), anaerobic sludge was used in the anaerobic/anoxic SBR as inoculum.Anaerobic/anoxic phase was studied and nitrite was added as electronic acceptor.A SDPB strain was screened and isolated and the classification status was studied by adopting traditional and modern molecular identification methods.The biological utilization of the bacterial strain under different nutrition and environment conditions was investigated.The result showed that the bacterium was facultative anaerobe and bore simultaneous shortcut denitrifying/phosphorus removing function.It belonged to Acinetobacter sp.according to its morphological, physiology, biochemical, properties and the analysis of 16S rDNA gene sequence with 99.3% similarity.The optimum carbon resource was sodium acetate.The bacteria used not only nitrite but also nitrate as electronic acceptor.The best pH value was 7 and the best temperature was 25℃.The appropriate temperature was 20—35℃.The growth of micro-organism was inhibited when the temperature was 10℃.The activity of microorganism decreased when the temperature was above 35℃.The highest removal efficiency of phosphate and nitrate were 82.94% and 82.99%,respectively.

    Production of epoxypropane from propene catalyzed by whole cells of Methylosinus trichosporium OB3b
    SU Tao, HAN Bing, YANG Cheng, WU Hao, JIANG Hao, LI Xin, XING Xinhui
    2009, 60(7):  1767-1772. 
    Abstract ( 696 )   PDF (920KB) ( 272 )  
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    The methane monooxygenase of methanotrophs is capable of catalyzing propene to produce epoxypropane directly in one step, without formation of by-products except water.Compared with the chemical synthesis method for production of epoxypropane, the biosynthesis has promising potential due to the mild reaction conditions, high selectivity and environmental friendliness.In this paper,the conditions were optimized for production of epoxypropane from propene with Methylosinus trichosporim OB3b whole cells cultivated by the traditional method, including temperatures, initial propene concentrations,sodium formate and MgCl2 concentrations, which are important factors affecting the epoxypropane biosythesis.Based on the optimization results, the performance of epoxypropane production carried out with M. trichosporium OB3b of high cell density was investigated,which was obtained by a novel rapid cultivation method developed by the authors.The final concentration of epoxypropane was almost four times of the highest productivity reported so far.

    Effects of CO content on selective non-catalytic reduction of NOx
    LV Hongkun, YANG Weijuan, ZHOU Junhu, ZHOU Zhijun, LIU Jianzhong, CEN Kefa
    2009, 60(7):  1773-1780. 
    Abstract ( 903 )   PDF (2504KB) ( 351 )  
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    An experimental study on the effects of CO content on selective non-catalytic reduction(SNCR)of NOx was performed in a quartz tube reactor,using ammonia and urea solution as N-agent.The results showed that as the CO content increased:(1)Both the SNCR temperature window and the optimal DeNOx temperature shifted towards a lower temperature.Simultaneously,the temperature window was narrowed and the optimal DeNOx efficiency decreased,especially when using ammonia as reductant.(2)The peak of N2O emission became higher.When using urea solution as the reductant,N2O emission temperature window extended towards a lower temperature mainly.In the case of ammonia,N2O emission temperature window extended to both higher and lower temperatures.(3)The slip emission curves of both NH3 and HNCO shifted to a lower temperature.When setting φ(CO)/φ(urea)constant,the optimal DeNOx temperature dropped slightly with the increase of ratio of ammonia to nitrogen in the feed(β),and there was no change of the emission regime profiles about NOx,N2O,NH3 and HNCO as β or oxygen content changed.

    Fusibility and flow properties of Shell gasifier slag
    SONG Wenjia, TANG Lihua, ZHU Xuedong, WU Yongqiang, RONG Yongqiao, ZHU Zibin
    2009, 60(7):  1781-1786. 
    Abstract ( 676 )   PDF (3444KB) ( 272 )  
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    The fusibility and flow properties of Shell gasifier slag were study in this paper.The physical properties of slag were analyzed with X-ray fluorescence, X-ray diffraction, and scanning electron microscopy.The fusion temperature, viscosity and lowestm tapping temperature for slag with the addition of fluxing CaO were measured by using high temperature fusion furnace and high temperature rotational viscometer.The thermodynamic computer package FactSage was used to predict the proportion of solid, the liquidus temperature as well as the mineral phase formed as a function of composition and temperature.The results showed that the fusion temperature, lowest tapping temperature and viscosity of slag in the temperature range of 1400—1500℃ decreased with increasing CaO content, whereas those values increase rapidly with CaO content higher than 35%.The effect of CaO on the liquidus temperature and the solid content at the same temperature calculated by FactSage was similar.The sub-liquidus phase predicted by FactSage transformed from the anorthite phase to the mullite phase with increasing CaO content.Also, the microstructure of quenched slag changed from a loose and porous state to rod-like crystallization.

    Thermal decomposition of biomass/polylactic acid during co-pyrolysis
    WANG Gang, LI Aimin, QUAN Cui
    2009, 60(7):  1787-1792. 
    Abstract ( 740 )   PDF (1663KB) ( 426 )  
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    Pyrolytic process has a promising potential for the environmentally friendly upgrading of biomass and other materials such as plastics, coal.In this study, the influence of a biopolymer, polylactic acid (PLA) on the pyrolysis of corncob was investigated by using a fast pyrolysis fixed-bed reactor.The results indicated that the co-processing of PLA with corncob increased liquefaction yield and a lower water content as a function of the corncob/PLA ratio was obtained.Furthermore, the thermal degradation of corncob, PLA and their blends in nitrogen was studied at different temperatures by using TGA/FTIR.The gas evolved during degradation was identified by in situ FTIR.The results showed obvious synergies between corncob and PLA during co-pyrolysis.

    Evolution of pore structure of biomass particles during pyrolysis
    FU Peng, HU Song, XIANG Jun, SUN Lushi, ZHANG Anchao, YANG Tao, JIANG Long
    2009, 60(7):  1793-1799. 
    Abstract ( 739 )   PDF (1947KB) ( 537 )  
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    The changes in pore structure characteristics of biomass particles during pyrolysis were studied.The samples were characterized by N2 isothermal adsorption/desorption method and scanning electronic microscopy (SEM).The results indicated that pyrolysis temperature had a notable impact on the pore structure and morphology of biomass char.Pyrolysis temperature was found to influence the size and the shape of char particles.A high temperature led to plastic deformation of particles resulting in smooth surfaces and large cavities.BET specific surface area first increased and then decreased.The change of pore volume was similar to that of BET specific surface area below 500℃.The fractal dimension (DFHH) calculated by fractal Frenkel-Halsey-Hill (FHH) equation could represent pore structure satisfactorily.The fractal analysis showed that pyrolysis temperature had a close relationship with DFHH.The fractal dimension could be correlated with BET specific surface area.

    能源和环境工程

    Structure and carbonation characteristics of dry potassium-based supported sorbent for CO2 capture

    ZHAO Chuanwen;CHEN Xiaoping;ZHAO Changsui
    2009, 60(7):  1800-1805. 
    Abstract ( 677 )   PDF (1531KB) ( 293 )  
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    The structure identification and carbonation characteristics of several potassium-based supported sorbents for CO2 capture were investigated with TGA,XRD,XRF,SEM and N2 adsorption method.Potassium-based sorbents were prepared by impregnation with potassium carbonate on supports,such as cocoanut activated charcoal(AC1),coal active carbon(AC2),silica gel(SG)and diatomite(DT)using the iso-volume impregnation method.The results showed that the K2CO3 loading amounts of AC1,AC2,SG and DT were 24.1%,22.5%,21.7% and 19.1% respectively.The surface area and pore volume of K2CO3/AC1 and K2CO3/AC2 were larger than others.In contrast,those of K2CO3/DT were small.For K2CO3/SG,pore volume was large but surface area was small.K2CO3/AC1 and K2CO3/AC2 showed excellent carbonation capacity.However,the carbonation capacities of K2CO3/SG and K2CO3/DT were low.The difference in carbonation capacity of those sorbents were attributed to the difference in pore structure,leading to different supported sorbents.

    Advanced nitrogen removal from landfill leachate with highly concentrated ammonia nitrogen via nitrite in SBR
    SUN Hongwei, WANG Shuying, WANG Ximing, SHI Xiaoning, PENG Yongzhen
    2009, 60(7):  1806-1811. 
    Abstract ( 1021 )   PDF (1080KB) ( 450 )  
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    The treatment of landfill leachate obtained from municipal solid waste (MSW) by using a lab-scale sequencing batch reactor(SBR) was studied.The aim of achieving and stabilizing partial nitrification and denitrification and the characteristics of advanced nitrogen removal were investigated.The experimental results showed that for 95 days running, stable partial nitrification with nitrite accumulation rate above 92.5% was achieved and maintained successfully.The stable biological nitrogen removal via partial nitrification and denitrification was realized and the average removal efficiency of NH+4 -N and TN were above 97.2% and 91.7%, respectively.The DO, ORP and pH could be used as the process control parameters for SBR reactor, because the characteristic points on the profiles indicated exactly the nitrification and denitrification end point.The nitrite oxidizing bacteria (NOB) was more sensitive than ammonia oxidizing bacteria (AOB) to the free ammonia (FA) and free nitrite acid (FNA), so the activity of NOB was inhibited by the synergetic effect of highly concentrated FA and FNA in the SBR nitrification.Furthermore, the key factor of achieving and stabilizing partial nitrification and denitrification for a long time was optimization of nitrifying microbial population by the assistance of process control, which was proved by FISH analysis.

    材料化学工程与纳米技术

    Tribological and corrosive behavior of PTFE composites filled with PTW in sulfuric acid solution

    WANG Huaiyuan;ZHU Yanji; FENG Xin; LU Xiaohua
    2009, 60(7):  1812-1817. 
    Abstract ( 839 )   PDF (1844KB) ( 439 )  
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    The tribological behavior and corrosion resistance of poly tetrafluoroethene (PTFE)composites filled with various amount of potassium titanate whiskers (PTW) and carbon fibers (CF) in sulfuric acid solution and under dry conditions were investigated respectively.The related mechanisms were discussed based on the SEM examinations of worn surfaces and optical micrographs of transfer behavior.The results indicated that the wear resistance of pure PTFE in acid increased by two orders of magnitude than that sliding in dry condition, and the friction coefficient was only 15.3% of that in dry condition.Compared with CF/PTFE composites, PTW/PTFE composites showed higher wear and corrosion resistance in acid.The wear rate and friction coefficient of PTFE in acid can be further decreased by PTW.At 15%(mass) PTW filler content, the wear rate of PTW/PTFE composites reached the lowest value, which increased the wear resistance of PTFE in acid by 13.8 times, and also 3.2 times higher than that of CF/PTFE composites.Owing to the cooling and lubricating effects of acid solution, the friction coefficient of PTFE composites decreased obviously than that in dry condition.However, the transfers onto the counterpart rings were significantly hindered when they were sliding in acid.When filler content was above 15%(mass), furrow and abrasive wear were the main mechanisms for PTFE composites whether sliding in dry condition or in acid.

    Numerical simulation for velocity and pressure in filling stage of injection molded parts with uneven thickness

    LIU Yongzhi;ZHAO Zhenfeng;MA Lan;SHEN Changyu
    2009, 60(7):  1818-1822. 
    Abstract ( 629 )   PDF (1730KB) ( 423 )  
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    The velocity and pressure in the filling stage of injection-molded parts with uneven thickness were simulated with finite element method(FEM).For given examples,the simulation results illustrated that the Hele-Shaw approximation did not work for the flow front and the area where the thickness was suddenly changed.The Hele-Shaw approximation tends to give larger error in the thick part if the thickness is changed.

    Synthesis and properties of ambient self-crosslinkable polyacrylate latex with sealed function
    LUO Chunhui, QU Jinqing, CHEN Huanqin
    2009, 60(7):  1823-1830. 
    Abstract ( 1492 )   PDF (635KB) ( 1099 )  
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    The ambient self-crosslinkable polyacrylate latexes with sealed function were synthesized by semi-batch seeded emulsion polymerization with diacetone acrylamide (DAAM), methyl acrylate (MMA), methacrylic acid (MAA) and butyl acrylate (BA) as co-monomers.The effects of DAAM and multiple emulsifiers on the emulsion polymerization stability and film performance were investigated.The results indicated that the emulsion polymerization stability decreased and the particle size of latex increased with increasing amount of DAAM, while the crosslinked degree of cured film increased and the water- or alcohol-resistance properties of cured film were improved.The optimal DAAM dosage was 3.0% (mass) and the molar ratio of DAAM to adipic dihydrazide (ADH) was 2∶1. On the other hand, the emulsion polymerization displayed high stability (low agglomeration and high monomer conversions), polyacrylate latexes exhibited good electrolyte stability, and its cured films possessed excellent sealed function.Sodium dodecyl sulphonate(SDS), nonyl phenol ethoxylates (OP-10) and OP-40 were used as multiple emulsifiers with 2.35% (mass) of the optimal dosage, the mass ratio of SDS to OP-10 and OP-40 was 1∶1.25, and the mass ratio of multiple emulsifiers dosages in seeded, core and shell was 1.5∶1∶2.The FTIR spectrum showed that the ketone carbonyl groups of DAAM reacted with hydrazide groups of ADH to form hydrazone (C=N) during film formation.TEM picture showed that the structures of particles were core and shell, and TGA curves indicated that the thermal stability of cured film decreased, which was attributed to the presence of C=N groups.

    Synthesis and characterization of monovinyl-functionalized silsesquioxane cage
    LIU Yong, ZHOU Yan, HUANG Fuwei, WANG Canfeng, SHEN Xuening, HUANG Farong
    2009, 60(7):  1831-1836. 
    Abstract ( 822 )   PDF (542KB) ( 420 )  
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    Monovinyl-functionalized silsesquioxane cage, 1,3,5,7,9,11,13-heptacyclopentyl-15-vinyl silsesquioxane(VinylPOSS), was prepared via the corner capping reaction of incompletely condensed silsesquioxanes, (C5H9)7Si7O9(OH)3, with vinyltrichlorosilane.VinylPOSS was characterized by FTIR, 1H NMR, 29Si NMR, 13C NMR, elemental analysis, WAXD and TGA.The yield of VinylPOSS increased with reaction time, when vinyltrichlorosilane reacted with (C5H9)7Si7O9(OH)3 for 10 h, the yield was 90%.VinylPOSS has good solubility in weak polar solvent,and it shows good thermal stability, its temperature with 5% decomposition is 283℃ and the temperature with 56% residue is 800℃.The reactivity of VinylPOSS with high hydrogen-containing silicone fluid (HHSF) was investigated.It can be reacted with HHSF by Michael additions at both α- and β- positions, and the reaction is mainly β-addition.

    Preparation of water-soluble ionic liquids by electrodialysis
    YANG Lanlan, LIU Lifen, LI Yiming, MAO Peiqing, XU Danqian
    2009, 60(7):  1837-1842. 
    Abstract ( 655 )   PDF (649KB) ( 263 )  
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    A new method was proposed to prepare water-soluble ionic liquids by using four-compartment electrodialysis.1-Ethyl-3-methylimidazolium tetrafluoroborate ([EMIm]BF4), used as a model ionic liquid, was synthesized.Operation voltage, feed concentration and the type of ion-exchange membrane had important impacts on the performances of the electrodialysis process, such as average current efficiency, energy consumption and product yield.Compared with the traditional method of chemical synthesis, this new method was more eco-friendly and economical.Less reaction time was needed though the reaction proceeded at room temperature.No traditional solvent was needed and higher purity was obtained by the new method.

    Preparation of carboxymethylcellulose from steam exploded crop straw
    YANG Ye, CHEN Hongzhang
    2009, 60(7):  1843-1849. 
    Abstract ( 676 )   PDF (1013KB) ( 798 )  
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    Crop straw resources are abundant in nature.In this study the crop straws were used as raw material for carboxymethylation after activation by steam explosion treatment.Then the high value-added carboxymethylcellulose(CMC) was separated from other components through solvent extraction according to their different physico-chemical properties.The results indicated that the best reaction condition was that the straws were carboxymethylated at 75℃ for 2 h with the liquid volume (ml)/solid mass (g), molar ratio of NaOH/SMCA and H2O/straw (ml∶g)were 18∶1, 4∶3 and 1∶2,respectively.Under the optimized reaction conditions, the yield of CMC in the products could reach 40.70% , the substitution degree (DS) of CMC obtained reached 0.91, which was similar to that prepared from straw α-cellulose, which possessed special characteristics of low viscosity.The CMC was characterized with FTIR and 1H NMR.Meanwhile, the lignin part with great industrial potential could also be separated from the products.Compared with the current utilization of high α-cellulose as raw material in the carboxymethylcellulose industry, the new process was not only lower cost, but also more simplified, and made full use of straw components.

    Effect of ODA content in mixed solvent of ODA and OD on luminescence of CdSe quantum dots
    JI Tianhao, LIANG Hui, SUN Jiayue, SUN Baoguo, ZHU Jun, GE Guanglu
    2009, 60(7):  1850-1854. 
    Abstract ( 838 )   PDF (1151KB) ( 453 )  
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    The monodisperse and uniform CdSe quantum dots (QDs) were synthesized in a mixed solvent of octadecylamine (ODA) and octadecanol (OD) by using the high-temperature solvent method.The diameter and optical properties of the QDs prepared under different reaction times and different ODA contents were characterized.The measurement results showed that with the increase of added ODA content, the diameter of the QDs was hardly influenced, whereas the PL quantum yield tended to increase.

    Homogeneous synthesis of cellulose acetate butyrates in ionic liquid
    CAO Yan, LI Huiquan, ZHANG Jun, HE Jiasong, ZHANG Yi
    2009, 60(7):  1855-1858. 
    Abstract ( 847 )   PDF (396KB) ( 878 )  
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    Cellulose acetate butyrates (CAB) were homogeneously synthesized in an ionic liquid, 1-allyl-3-methyl-imidazolium chloride (AmimC1).By a sequence of first adding butyric anhydride and then acetic anhydride in the cellulose/AmimCl solutions, CAB products with the butyryl contents ranging from 33% to 47%(mass) were obtained.NMR analysis showed that among the three OH groups of the anhydroglucose unit (AGU) of the synthesized CAB, the distribution of the butyryl moieties showed a preference at the C6 position, while the partial degree of substitution of acetyl moieties at the C6 position showed the minimum values.Solubility measurement showed that CAB samples readily dissolved in the common organic solvents, such as methyl ethyl ketone, dichloromethane, and ethyl acetate.

    材料化学工程与纳米技术

    Application of variable molecular connectivity indices for topological research on diamagnetic susceptibilities of organic compounds

    MU Lailong;HE Hongmei

    2009, 60(7):  1859-1865. 
    Abstract ( 640 )   PDF (4018KB) ( 146 )  
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    For predicting the molar diamagnetic susceptibilities of organic compounds, a variable molecular connectivity index mχand its converse index mχ based on adjacency matrix of molecular graphs and the variable atomic valence connectivity index δI were proposed.The optimal values of parameters a, b, and y included in definition of δ′i,mχand mχcan be found by optimization method.When a=1.10, b=2.8, and y=0.36, a good five-parameter model can be constructed from mχand mχby using the best subsets regression analysis method for the molar diamagnetic susceptibilities of organic compounds.The results showed that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an organic compound.

    Explosion characteristics and applications of multicomponent explosive gas mixture consisting of CH3OH, NH3 and air
    HU Rui, WU Xiaohua, WENG Xuexiang, MA Jingmeng, HU Yaoyuan
    2009, 60(7):  1866-1872. 
    Abstract ( 756 )   PDF (468KB) ( 504 )  
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    Systematic studies were carried out to investigate the explosion characteristics and morphology of the multicomponent explosive gas mixture CH3O-NH3-air.It was found that the explosive limit of concentration of the gas mixture (CH3OH∶NH3=1∶1.1) was 12.85%—45.25%.There were only two explosion morphologies for the explosive gas mixture.One is cool flame, and the other is deflagration.Furthermore, strong detonation was not observed during the explosion experiments.N2 and steam did have some inert effect on the explosion of the explosive gas mixture, while NH3 had a clear damping effect on the explosion for the gas mixture with CH3OH and air.With the decrease of ratio of CH3OH to NH3, the degree of explosive danger, explosion maximum pressure and pressure rise rate decreased at the same time.The present work provides a good guidance for the technological upgrade of methanol ammoxidation in industrial production due to its good effectiveness of explosion suppression and powerful explosion-proof measure.It also has a potential application of methanol ammoxidation because of its substantial increase in productivity, low investment, rapid implementation, and high economic benefits.