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Table of Content
05 March 2012, Volume 63 Issue 3
    Group contribution methods for prediction of thermophysical properties and phase behavior of ionic liquids
    XIONG Yan, DING Jing, YU Dahong, PENG Changjun, LIU Honglai
    2012, 63(3):  667-676.  doi:10.3969/j.issn.0438-1157.2012.03.001
    Abstract ( 3037 )   PDF (478KB) ( 891 )  
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    Ionic liquids(ILs) are molten salts of great industrial interest and are now attracting the attention of a large number of researchers due to their unique characteristics, i.e., wide liquid range, thermal stability, negligible vapor pressure, tunable physicochemical properties and many others.  Thousands of ILs have been designed and synthesized for specific applications in different fields in both academic and industrial studies in the past decades. Thermophysical properties and phase behavior of ILs, such as melting points, densities, gas solubilities, viscosities, conductivities and vapor-liquid equilibrium are required in practical applications. Although a large amount of experimental data have been measured and reported, the number of potential ILs is so enormous, some say as many as 1012 to 1018,that it is impossible to determine all these data by laboratory methods which are complicated, time-consuming and sometimes are even hard to be developed. In recent years, many attempts have succeeded in developing methods to estimate the physical properties of unknown ILs in order to facilitate the design of new modifications and reduce the expenses in experimental work. Group contribution(GC) method is one kind of the successful predicting methods practicable for designing and selecting suitable ILs, in which the property of a compound is a function of structurally-dependent parameters, which are determined by summing the frequency of each group occurring in the molecule times its contribution. Since the number of functional groups is much smaller than the number of molecules, it indicates the great potential opportunity that properties of the whole series of ILs may be predicted rapidly and accurately if only a few data of ILs with similar molecular structure in the series are available. This review highlights a great deal of GC models for prediction of thermophysical properties of ILs, including melting point, viscosity, density, heat capacity, conductivity, sonic speed, ecotoxicity, surface, critical and transport properties, and some GC correlating models for estimation of phase behavior of mixtures containing ILs are summarized, too. At last, the research foreground of GC methods is prospected.
    An overview on lignocellulose pretreatment and recalcitrant characteristics
    CUI Mei1,HUANG Renliang2,SU Rongxin2,QI Wei2,ZHANG Yimin1,HE Zhimin2
    2012, 63(3):  677-687.  doi:10.3969/j.issn.0438-1157.2012.03.002
    Abstract ( 2745 )   PDF (1108KB) ( 1362 )  
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    Lignocellulose is the most abundant renewable biomass on the earth. Enzymatic hydrolysis of cellulosic polysaccharide is key step of lignocellulose biorefineries. To enhance efficiency of cellulose hydrolysis, pretreatment is necessary for effectively breaking its recalcitrant structure.  So, great attentions have been paid for design of pretreatment technologies to crack recalcitrant characteristics of lignocellulose. In this paper,the latest research progresses on lignocellulose pretreatment and recalcitrant characteristics were reviewed, focusing on the new pretreatment technologies and their main advantages,including combined pretreatment, cold pretreatment, green solvents pretreatment and electrochemical approach. Otherwise, the influence of recalcitrant characteristics, such as lignin, crystallinity, accessibility, on cellulose hydrolysis was discussed. The new methods used for analysis of recalcitrant characteristics and the new insight obtained are highlighted in this review. These are useful for evaluation of pretreatment technologies, and identification of key factors that limit cellulose hydrolysis, and can also be a basis for design and screen of appropriate pretreatment technologies, as well as for understand of lignocellulose hydrolysis mechanism.
    Correlation and prediction for vapor-liquid equilibria of dimethyl sulfide-pyridine-N,N-dimethylacetamide multicomponent system
    GAO Daming1,2,ZHANG Junlong1,ZHU Dechun1,2,ZHANG Hui1,CHEN Hong1,SUN Hong1,SHI Jianjun1,2
    2012, 63(3):  688-697.  doi:10.3969/j.issn.0438-1157.2012.03.003
    Abstract ( 2304 )   PDF (471KB) ( 742 )  
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    Isobaric vapor-liquid equilibrium (VLE) data at 101.325 kPa for the three binary systems containing dimethyl sulfide-pyridine, dimethyl sulfide-N,N-dimetylacetamide and pyridine-N,N-dimetylacetamide and the ternary system containing dimethyl sulfide-pyridine-N,N-dimetylacetamide were measured by different liquid phase compositions using an ebullionmeter. The activity coefficients were correlated with the Wilson, NRTL, Margules, van Laar and UNIQUAC models. The experimental T-x data are used to these model parameters through the least square method, and these parameters in turn are used to calculate vapor-phase compositions. Moreover, the vapor-phase compositions had been predicted from Tpx according to the function of molar excess Gibbs energy by the indirect method. The activity coefficients are useful to calculate excess Gibbs function for the three binary systems. The VLE data of the ternary system were correlated based on Wilson, NRTL, Margules, van Laar and UNIQUAC model parameters of these binary systems in order to build the thermodynamic model of VLE for the ternary system and obtain the vapor-phase compositions and the calculated bubble points, respectively. The thermodynamic consistency of the experimental VLE data were checked out by means of the Herington test for the binary systems and the McDermott-Ellis test for the ternary system, respectively, and the results showed that VLE data for these systems strictly satisfied thermodynamic consistency.
    Heat transfer model for particles with discrete element method
    BU Changsheng,CHEN Xiaoping,LIU Daoyin,DUAN Yufeng
    2012, 63(3):  698-704.  doi:10.3969/j.issn.0438-1157.2012.03.004
    Abstract ( 2386 )   PDF (858KB) ( 679 )  
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    Heat conduction in granular assemblies plays an important role in industrial applications. In this paper, the details of heat transfer mechanism are considered in particle scale. The conduction resistances of solid interior, rough surface, gas film between solids, and gas-gap between contacted surfaces are modeled and coupled with discrete element method to deduce a heat transfer model. Numerical simulations are performed to investigate the effects of particle diameter, specific thermal capacity, thermal conductivity of particles and compressive load on effective thermal conductivity(ETC) in fixed beds. The predicted ETC is compared with experimental and simulated data in literature, indicating that the presented model can predict ETC satisfactorily, which provides a useful tool for studying heat transfer in particle assemblies.
    Pressure drop and velocity distribution in two-stage gasifier
    JIN Weilong,WANG Yifei,SU Pan,PENG Kang,GUO Qinghua
    2012, 63(3):  705-712.  doi:10.3969/j.issn.0438-1157.2012.03.005
    Abstract ( 1824 )   PDF (477KB) ( 437 )  
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    The two-stage gasifier with heat recovery via chemical energy can improve heat recovery of high-temperature syngas effectively. In order to understand the flow pattern in the new two-stage gasifier, a cold model experimental device was set up. The pressure drop of second stage and velocity distribution in the gasifier were examined. The results showed that Montiller empirical equation could accurately predict the pressure drop of the second stage. When gas reached the bed surface of the second stage, an impact region was formed. The axial velocity attenuation equation of single nozzle on the top and downward radial velocity attenuation equation of four nozzles impacting were fitted out. Regarding the radial distribution of axial velocity, the center axial velocity appeared to be the largest and decayed the fastest. The distance of axial position from pipe flow region of four nozzles impacting was shorter than single nozzle on the top by 1.8D.
    Shell side heat transfer enhancement in twisted elliptical tube heat exchanger
    TAN Xianghui, SUN He, ZHANG Lizhen, ZHU Dongsheng
    2012, 63(3):  713-720.  doi:10.3969/j.issn.0438-1157.2012.03.006
    Abstract ( 2727 )   PDF (555KB) ( 543 )  
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     Heat transfer and pressure drop of twisted elliptical tube heat exchanger with FrM=79 are tested in the present work. Based on the experimental result, the application range of previous correlations for twisted elliptical tube heat exchanger with FrM>232 and FrM=64 is analyzed, and correlations of the tested heat exchanger with FrM=79 are derived. The testing result indicates that there exists a change of fluid flowing state when Res increases to 8000. Two heat exchangers with similar geometric parameters to the tested one but supported by segmental baffles and rod baffles are designed. Their shell side heat transfer coefficients and pressure drops are calculated with Bell-Delaware method and Gentry’s method, respectively. Heat transfer coefficients and pressure drops of the two designed heat exchangers are compared with the tested twisted elliptical tube heat exchanger. Comprehensive performance of the three heat exchangers is studied. The twisted elliptical tube heat exchanger gives the highest heat transfer coefficient and lowest pressure drop. This type of heat exchanger has the advantages of segmental heat exchanger and rod baffle heat exchanger and will be widely used in the industry.
    Water to water heat transfer on shell-side of trisection helical baffle heat exchangers
    DONG Cong, CHEN Yaping, WU Jiafeng, CAO Ruibing, SHENG Yanjun, NI Minglong
    2012, 63(3):  721-727.  doi:10.3969/j.issn.0438-1157.2012.03.007
    Abstract ( 2442 )   PDF (1280KB) ( 615 )  
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    Experimental study was conducted in trisection helical baffle heat exchangers with three sector baffle schemes of tilt angles 10°,15° and 20°,an ellipse baffle scheme of tilt angle 15°,and an axial overlap sector baffle scheme of tilt angle 20°,in contrast to a segmental baffle heat exchanger. Each helix heat exchanger has 48 tubes with layout of one third division of shell cylinder for each baffle, while the segmental baffle heat exchanger has 49 tubes. The data of the shell side, Nusselt number Nuo, axial Euler number Euz,o, and comprehensive performance indicator Nuo/Euz,o are presented versus the shell side axial Reynolds number Rez,o. The results show that the heat exchanger with the scheme of periphery connected sector baffles with tilt angle of 20° has the best performance, whose average comprehensive performance indicator Nuo/Euz,o is 69.8% higher than that of segmental baffle heat exchanger, while the comprehensive performance indicator of the scheme with tilt angle 10°is lower than that of segmental baffle scheme. With the same tilt angle, the performance with the periphery connected connection baffle scheme is better than that with the axial overlap baffle scheme, and the performance with the sector baffle scheme is better than that with the ellipse baffle scheme.
    Heat transfer enhancement of double-pipe heat exchanger inserted with rotors
    ZHANG Zhen, DING Yumei, YAN Hua, YANG Weimin
    2012, 63(3):  728-732.  doi:10.3969/j.issn.0438-1157.2012.03.008
    Abstract ( 2808 )   PDF (540KB) ( 701 )  
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    Enhanced heat transfer technology is an energy-saving technology. For new types of tube inserts, the mechanism of the rotors-assembled device for heat transfer enhancement and automatic cleaning is introduced in this paper. Experiments were carried out in order to study the heat transfer and friction characteristics of the tube inserted with helical blade rotors and discrete blade rotors. An experiment with a smooth tube was used to calibrate the experimental system and data reduction method. The experimental results show that the Nusselt number from the tube inserted with rotors is higher than that of plain tube within the experimental range of Reynolds number, though the friction factor of the tube with rotors inserted is slightly higher. The comparison of the tubes inserted with helical blade rotors and discrete blade rotors shows that the former present higher Nusselt number, lower friction factor and higher PEC value, indicating that the comprehensive performance of helical blade rotor is better.
    Boiling heat transfer characteristics of nano-refrigerant CuO/R141b flowing in smooth tube
    SUN Bin, QIAN Zheng
    2012, 63(3):  733-739.  doi:10.3969/j.issn.0438-1157.2012.03.009
    Abstract ( 3105 )   PDF (623KB) ( 579 )  
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    The boiling heat transfer characteristics of nano-refrigerant CuO/R141b flowing in a horizontal tube was studied experimentally. In order to verify the reliability of the experiment, the experimental results of boiling heat transfer of flowing pure HCFC141b were compared with Chenmin formula. The absolute average error was 7.4% when compared the calculated value with experimental results, which is satisfactory. The experimental condition was: mass flow rate 100—350 kg·m-2·s-1,vapor quality 0.3—0.8,the total length of copper tube 1.4 m and its inside diameter 10 mm. The heat transfer was investigated at different mass fractions of nanoparticles, different vapor quality and different mass flow rates. The boiling heat transfer is enhanced by adding nanoparticles, and the improvement is related to the mass flow rate, vapor quality and nanoparticle concentration. At the mass flow rate of 120 kg·m-2·s-1 and mass fractions of CuO nanoparticles of 0.1%,0.2% and 0.3%,the heat transfer coefficient increases 7%,10.4%,and 16.6%,respectively.
    Departure-site spacing for liquid columns falling between horizontal circular tubes
    LV Kai, WANG Xiaofei, ZHANG Ying, HE Maogang
    2012, 63(3):  740-745.  doi:10.3969/j.issn.0438-1157.2012.03.010
    Abstract ( 1842 )   PDF (539KB) ( 441 )  
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    The departure-site spacing between liquid columns was measured for water, ethylene glycol, water and ethylene glycol binary mixture with volume fraction 0.5/0.5 on eight different orifice configurations with a visualization method. The influences of flow rate, tube spacing, surface structure and orifice configuration on departure-site spacing were investigated for the subcooled liquid columns flowing between horizontal tubes at the ambient temperature and normal pressure. Under the conditions of this study, the departure-site spacing increases with the decrease of Re for high-Ga flow. For a fixed Re,the departure-site spacing increases with the increase of tube spacing. The surface structure and thermo-physical properties of fluid influence the departure-site spacing. Bigger hole diameter brings smaller departure-site spacing at a fixed distance between adjacent holes, while larger distance between adjacent holes leads to larger departure-site spacing at a fixed hole diameter.The departure-site spacing between liquid columns was measured for water, ethylene glycol, water and ethylene glycol binary mixture with volume fraction 0.5/0.5 on eight different orifice configurations with a visualization method. The influences of flow rate, tube spacing, surface structure and orifice configuration on departure-site spacing were investigated for the subcooled liquid columns flowing between horizontal tubes at the ambient temperature and normal pressure. Under the conditions of this study, the departure-site spacing increases with the decrease of Re for high-Ga flow. For a fixed Re,the departure-site spacing increases with the increase of tube spacing. The surface structure and thermo-physical properties of fluid influence the departure-site spacing. Bigger hole diameter brings smaller departure-site spacing at a fixed distance between adjacent holes, while larger distance between adjacent holes leads to larger departure-site spacing at a fixed hole diameter.
    Application and optimization of fin-and-tube heat exchangers with longitudinal vortex generators
    HE Yaling,CHU Pan,XIE Tao
    2012, 63(3):  746-760.  doi:10.3969/j.issn.0438-1157.2012.03.011
    Abstract ( 2682 )   PDF (3007KB) ( 756 )  
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    The longitudinal vortex generator (LVG)can significantly enhance the heat transfer in fin-and-tube heat exchangers with a moderate pressure loss penalty. A 3-D numerical simulation was employed to investigate the flow and heat transfer characteristics of fin-and-tube heat exchangers. The optimizations for critical parameters of vortex generator, i.e. , the attack angle, number and position of LVG, were performed. The results show that the enhancement of heat transfer on the airside can surpass the increase of the pressure drop in a fin-and-tube exchanger with three pairs of rectangular winglets and an attack angle of 15°. Compared with the conventional configuration, the heat transfer coefficient of the enhanced configuration is improved by 71.3%—87.6% while the pressure loss is increased by 54.4%—72%. The average heat transfer coefficient on the airside increases with the number of vortex generator, but the local heat transfer is affected little by the number of vortex generator after the fifth tube. Compared with the inline arrangement of vortex generators, the staggered arrangement of vortex generators can further reduce the pressure loss penalty while maintain the enhanced heat transfer.The longitudinal vortex generator (LVG)can significantly enhance the heat transfer in fin-and-tube heat exchangers with a moderate pressure loss penalty. A 3-D numerical simulation was employed to investigate the flow and heat transfer characteristics of fin-and-tube heat exchangers. The optimizations for critical parameters of vortex generator, i.e. , the attack angle, number and position of LVG, were performed. The results show that the enhancement of heat transfer on the airside can surpass the increase of the pressure drop in a fin-and-tube exchanger with three pairs of rectangular winglets and an attack angle of 15°. Compared with the conventional configuration, the heat transfer coefficient of the enhanced configuration is improved by 71.3%—87.6% while the pressure loss is increased by 54.4%—72%. The average heat transfer coefficient on the airside increases with the number of vortex generator, but the local heat transfer is affected little by the number of vortex generator after the fifth tube. Compared with the inline arrangement of vortex generators, the staggered arrangement of vortex generators can further reduce the pressure loss penalty while maintain the enhanced heat transfer.
    Effects of deflector structure on performance of micro-channel evaporator with parallel flow
    LIU Wei
    2012, 63(3):  761-766.  doi:10.3969/j.issn.0438-1157.2012.03.012
    Abstract ( 2440 )   PDF (535KB) ( 772 )  
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    Three different micro-channel evaporators with parallel flow were designed with the only difference in the structure of the first deflector,with the same open area but different number and location of holes. The performance of three evaporators was tested with refrigerant 134a under the same conditions.  Flow and heat transfer characteristics in the evaporators were investigated with different number and location of holes in deflectors. The results show that the structure of deflector affects the flow and heat transfer performance of the evaporator remarkably. An appropriate structure of deflector can improve the uniformity of flow distribution, cooling capacity and pressure drop. The increase in pressure drop is faster than that of cooling capacity. With the same open area of holes in the deflector, their number and location in deflectors have no effect on the resistance coefficient of the evaporator. Insufficient holes in deflectors may generate the mal-distribution of refrigerant and deteriorate the heat transfer performance of the evaporator. When the holes in the deflector are not in the middle of two neighboring flat tubes,flow of the refrigerant is limited and the uniformity of flow distribution gets worse. The optimal structure of the first deflector is that the number of holes is half of that of the flat tubes,and the projection location of each hole has the same distance from two adjacent flat tubes.
    Experimental and numerical study on liquid-liquid dispersion in static mixer
    WANG Xiugang,GUO Wali,WU Jianhua
    2012, 63(3):  767-774.  doi:10.3969/j.issn.0438-1157.2012.02.013
    Abstract ( 2159 )   PDF (2651KB) ( 1023 )  
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    Distributive mixing and dispersive mixing for the dispersion of toluene in water in a Kenics static mixer were investigated by means of numerical modelling tools and experimental study. Dispersive mixing performance was described as Sauter mean diameter (SMD), which was measured by photographic technique(direct shooting method on a cross-section).Polynomial expression of SMD was built by three factor Box-Behnken design and response surface analysis, which was based on Design Expert 7.0 code. A physical model of the static mixer was built, which was the same as the experimental apparatus. Mixture multiphase model and standard k-εturbulence model were chosen for CFD modeling. The contours of concentration field and non-uniform coefficient were obtained. Distributive mixing performance was described as non-uniform coefficient, which was calculated by contours of concentration field. The total deviation between simulated and experimental pressure drops was less than 15% in this way. Thus, the simulated results showed good agreement with the experimental results. The results showed that liquid-liquid dispersion in static mixer could be attributed to the combination of distributive mixing and dispersive mixing. A fully developed state for both mixing processes could be achieved through 6—8 mixing units. The influences of superficial velocity, volume fraction of dispersed phase and pipe diameter on fully developed SMD were obvious, but the influence of superficial velocity was most significant. The non-uniform coefficient in fully developed section decreased to below 0.05, so that the static mixer had excellent performance on distributive mixing under wider experimental conditions.
    Flow behavior in grooves with foam walls for sandwich panels
    LEI Bo1,ZHOU Chixing1,YU Wei1,ZHANG Yu2,ZHOU Hua2,WANG Jian2
    2012, 63(3):  775-780.  doi:10.3969/j.issn.0438-1157.2012.03.014
    Abstract ( 1904 )   PDF (788KB) ( 589 )  
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    Foam core sandwich panels are widely used in many technical fields, especially in aerospace and wind power structures, due to their high specific strength and high specific stiffness. Among the various manufacturing processes for sandwich panels, vacuum assisted resin transfer molding (VARTM) is used extensively for manufacturing large composite structures. The success of VARTM depends upon the complete filling of the mold with adequate wetting of the fiber preform. The addition of grooves on the surface of the low-density core is used to shorten the fill time, because of the high permeability of grooves. Therefore, the resin flow through the grooves is an important step to ensure that the resin infusion process can be finished before the resin gels. The flow characteristics in grooves with impermeable foam walls for sandwich panels were investigated through experimental observations. An empirical equation for the volume flow rate in a glass tube and cylindrical grooves with impermeable foam walls was obtained. It was shown that the volume flow rate was a function of pressure drop, pipe dimension and fluid viscosity. When compared to pipe flow with no-slip boundary conditions, the flow ability in grooves dropped by about 40%. This was ascribed to the rough surface of grooves and demonstrated by scanning electron microscope (SEM),which clearly showed that there were many broken or uncracked bubbles distributed in the foam walls. An equivalent permeability was introduced to describe the flow capacity in the grooves. The grooves were treated as a porous medium whose permeability represented the average flow capacity in grooves,and the empirical Darcy’s Law was used to calculate the average velocity in grooves. Then the equivalent permeability equation for pipe flow in grooves with impermeable foam walls was obtained. This equation can be used for quick engineering estimate of equivalent permeability in grooves.
    Starting characteristics of sodium heat pipe in metrology based on “flat-front” startup model
    JIAO Yonggang,XIA Guodong,ZHOU Mingzheng,WANG Wei
    2012, 63(3):  781-787.  doi:10.3969/j.issn.0438-1157.2012.03.015
    Abstract ( 1732 )   PDF (420KB) ( 607 )  
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    The structure and characteristics of the sodium heat pipe in metrology were described. The flat-front startup model for the heat pipe was established and used to analyze the starting characteristics of the heat pipe. As an example, with the input power of 1000 W,the axial temperature distribution in the wall at the startup of heat pipe was calculated and compared with the literature values,indicating that the flat-front startup model is applicable to the sodium heat pipe in metrology. Turning point temperature is an important parameter in startup process of high temperature heat pipe. The turning point temperature of the sodium heat pipe and the start-up time under different input power were analyzed. With the vapor channel diameter of 100 mm and vapor density 0.31×10-4kg·m-3,the transition temperature is 628.2 K. With the input power of 800 W, 1000 W, and 1200 W,the time for the hot-zone to move 300 mm in the heat pipe is 1200 s,919 s and 681 s,respectively. The sodium heat pipe has a larger diameter, which makes the heat pipe start easily without considering the limitations of heat pipe generally.
    Numerical analysis on thermal processes in coupled coking and combustion chambers of coke oven
    JIN Ke1,FENG Yanhui1,ZHANG Xinxin1,LIN Wei1,ZHANG Changqing2,YANG Junfeng2,MA Xiaobo2
    2012, 63(3):  788-795.  doi:10.3969/j.issn.0438-1157.2012.03.016
    Abstract ( 2574 )   PDF (2502KB) ( 571 )  
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    To describe fluid flow, combustion and heat transfer in coke oven,a three-dimensional transient mathematical model with coupled coking and combustion chambers was developed and solved numerically. The calculated central temperature of the coke was compared with measured data. Three different evaporation models were compared. Effects of operational factors such as temperature, moisture content and density of charging coal were investigated. It is shown that the proposed model is suitable for describing thermal processes in the coke oven. It reveals whether the temperature distribution is uniform along the height of the chambers with coking evolution. Some measures may be used to improve the production efficiency, such as preheat, adjustment of moisture content,and densification for charging coal. This work is theoretically valuable for the operation of coke oven.
    Flow regime identification of gas/liquid two-phase flow based ICA and RBF neural networks
    ZHOU Yunlong,GU Yangyang
    2012, 63(3):  796-799.  doi:10.3969/j.issn.0438-1157.2012.03.017
    Abstract ( 1634 )   PDF (357KB) ( 580 )  
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    It is the key issue of two-phase flow research to identify the flow type. The variability of two-phase flow medium leads to diversity and randomness of two-phase patterns, so it is difficult to identify the flow pattern effectively. Thinks to independent component analysis (ICA) fixed point algorithm,featuring fast convergence speed and no need of the introduction of some iterative process parameters,such as regulated step,in this paper the method named ICA-RBF was developed,which included two steps:first,applying the fixed point algorithm of negative entropy to extract convection-type characteristic parameters; second,identifying the parameters by radial basis function(RBF) neural network. Moreover, other two means, i.e. wavelet packet decomposition and singular value decomposition were introduced to extract feature from the same set of data. Through experimental comparison, it was concluded that ICA-RBF had better recognition results as well as simpler inspection process steps, which could reduce a lot of man-made errors and obtain more accurate and convincing result.It is the key issue of two-phase flow research to identify the flow type. The variability of two-phase flow medium leads to diversity and randomness of two-phase patterns, so it is difficult to identify the flow pattern effectively. Thinks to independent component analysis (ICA) fixed point algorithm,featuring fast convergence speed and no need of the introduction of some iterative process parameters,such as regulated step,in this paper the method named ICA-RBF was developed,which included two steps:first,applying the fixed point algorithm of negative entropy to extract convection-type characteristic parameters; second,identifying the parameters by radial basis function(RBF) neural network. Moreover, other two means, i.e. wavelet packet decomposition and singular value decomposition were introduced to extract feature from the same set of data. Through experimental comparison, it was concluded that ICA-RBF had better recognition results as well as simpler inspection process steps, which could reduce a lot of man-made errors and obtain more accurate and convincing result.
    Investigation of micro- or nano-scaled particle motion and deposition in square pore with natural convection
    LI Qi,DAI Chuanshan
    2012, 63(3):  800-805.  doi:10.3969/j.issn.0438-1157.2012.03.018
    Abstract ( 2442 )   PDF (2826KB) ( 742 )  
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    Dispersion and deposition of micro- or nano-scaled particles in a sudden expansion and attraction square pore were investigated, especially in different natural convection cases. Both the flow and temperature fields were simulated by using the lattice Boltzmann method (LBM).A two dimensional D2Q9 BGK model was used in the simulation. In addition to drag force, Saffman force and gravity,Brownian force was also taken into account due to the small size of particles. The trajectories of particles in the vortical flow field in a sudden small expansion and attraction square pore were simulated with the same Reynolds number,different Rayleigh numbers(Ra=102—105),different Stokes numbers(Stk=0.001,0.01,0.1,1,that was,particle diameters were respectively 5.5 μm,17.4 μm,54.8 μm,174 μm).In addition,the number and the position of deposited particles on the bottom with natural convection were analyzed by comparing with the case without natural convection. Moreover,the total deposition efficiencies were obtained under various Ra and Stk values. The results showed that the trajectories of particles varied with different Stokes numbers,but with the same Reynolds numbers. The Ra number showed a strong influence on deposition efficiency while Stk number was less than 0.1,and the deposition efficiency did not show a monotonic change with a decrease of Stk number. Natural convection in the present configuration could either increase or decrease the total deposition efficiency compared with the isothermal case. An intense natural convection could result in a high deposition efficiency, especially for the case of low Stokes number and high Rayleigh number. The goal of the paper was to give a preliminary explanation for the injectivity reduction of a reinjection well in geothermal uses, and the results also indicated that the blocking due to particle deposition in a pore happened easier while injecting cold water. This is true in many realistic reinjection tests for geothermal uses.Dispersion and deposition of micro- or nano-scaled particles in a sudden expansion and attraction square pore were investigated, especially in different natural convection cases. Both the flow and temperature fields were simulated by using the lattice Boltzmann method (LBM).A two dimensional D2Q9 BGK model was used in the simulation. In addition to drag force, Saffman force and gravity,Brownian force was also taken into account due to the small size of particles. The trajectories of particles in the vortical flow field in a sudden small expansion and attraction square pore were simulated with the same Reynolds number,different Rayleigh numbers(Ra=102—105),different Stokes numbers(Stk=0.001,0.01,0.1,1,that was,particle diameters were respectively 5.5 μm,17.4 μm,54.8 μm,174 μm).In addition,the number and the position of deposited particles on the bottom with natural convection were analyzed by comparing with the case without natural convection. Moreover,the total deposition efficiencies were obtained under various Ra and Stk values. The results showed that the trajectories of particles varied with different Stokes numbers,but with the same Reynolds numbers. The Ra number showed a strong influence on deposition efficiency while Stk number was less than 0.1,and the deposition efficiency did not show a monotonic change with a decrease of Stk number. Natural convection in the present configuration could either increase or decrease the total deposition efficiency compared with the isothermal case. An intense natural convection could result in a high deposition efficiency, especially for the case of low Stokes number and high Rayleigh number. The goal of the paper was to give a preliminary explanation for the injectivity reduction of a reinjection well in geothermal uses, and the results also indicated that the blocking due to particle deposition in a pore happened easier while injecting cold water. This is true in many realistic reinjection tests for geothermal uses.
    Simulation model and experimental study on parallel flow condenser based on two-phase flow regime
    HU Haomang1,CHEN Huanxin1,WANG Yanzhong1,XIE Junlong1,DENG Jiasheng2,ZHOU Along1
    2012, 63(3):  806-811.  doi:10.3969/j.issn.0438-1157.2012.03.019
    Abstract ( 2146 )   PDF (653KB) ( 667 )  
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    The pressure drop and heat transfer of refrigerant depend on the mass velocity, phase state and flow regime in the non-circular microchannel of parallel flow condenser. However, the flow regime is not considered in available researches, in which the predictions on pressure drop and heat transfer coefficients in the two-phase flow are not satisfactory. In this study, a model with different flow regimes is employed based on the two-phase flow on refrigerant side and the pressure drop is predicted from the change of flow regime. The coupling between pressure drop and heat transfer is investigated. A simulation model on the parallel flow condenser is established and studied experimentally under 6 different working conditions. It is found that the multiple-flow-regime model with intermittent flow model, overlap model and annular flow model as submodels can be used to predict the heat transfer and flow characteristics of microchannel condenser. The model may provide a reference for optimization design for parallel flow condenser.
    Acidic ionic liquid-catalyzed synthesis of 1,3-diphenyl urea from aniline and carbon dioxide
    YAO Sujie,ZHAO Xinqiang,AN Hualiang,WANG Yanji
    2012, 63(3):  812-818.  doi:10.3969/j.issn.0438-1157.2012.03.020
    Abstract ( 3164 )   PDF (450KB) ( 582 )  
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    A novel green process for the synthesis of 1,3-diphenyl urea(DPU) by reaction of aniline with carbon dioxide was studied,and the emphasis was put on the investigation of the catalytic performance of Lewis acidic ionic liquids. Firstly, the effects of a series of alkaline or Lewis acid catalysts and solvents on the synthesis of DPU were investigated, and it was found that AlCl3/acetonitrile system showed excellent catalytic performance. Then the influence of the kind of cation and anion in ionic liquids, initial pressure of CO2, reaction time,reaction temperature,and catalyst dosage was discussed in the presence of chloroaluminate ionic liquids as both Lewis acid catalyst and solvent. Under the reaction conditions of [Bmim]Cl-AlCl3 as both the catalyst and solvent,initial pressure of CO2 of 1 MPa,reaction time of 7 h,reaction temperature of 160℃,and mass ratio of AlCl3 to aniline of 1∶1,the conversion of aniline was 18.1%,and the yield and selectivity to DPU were 17.9% and 98.9%,respectively. Additionally, a plausible catalytic reaction mechanism was also proposed.
    Kinetics and DFT study of complete liquid-phase catalyst for dehydration of methanol to dimethyl ether
    HU Jianshui, WANG Chengjun, LIU Lei, ZUO Zhijun, HUANG Wei, XIE Kechang
    2012, 63(3):  819-825.  doi:10.3969/j.issn.0438-1157.2012.03.021
    Abstract ( 2431 )   PDF (1504KB) ( 748 )  
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    The kinetics and density functional theory (DFT) of dimethyl ether (DME) synthesis from methanol dehydration over AlOOH catalysts prepared by complete liquid phase method in a slurry bed reactor was investigated. The kinetic model showed that the rate-limiting step of CH3OH dehydration over AlOOH catalysts was coadsorption of two methanol molecules. The process of DME synthesis from methanol dehydration over AlOOH(100) surface in liquid paraffin was also studied with DFT,and the reaction process and activation energy of the rate-limiting step were consistent with the kinetic model,further indicating that the model could reasonably describe the process of DME synthesis from methanol dehydration over AlOOH catalysts by complete liquid phase method.
    Preparation and extraction of onion essential oil by ionic liquid and ultrasound-microwave-assisted method
    CAO Hong1,DUAN Haiyan1,LI Chun1,2,XIN Na1,LI Jun1,LI Bingqi1
    2012, 63(3):  826-833.  doi:10.3969/j.issn.0438-1157.2012.03.022
    Abstract ( 3319 )   PDF (546KB) ( 707 )  
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    To improve enzyme catalytic efficiency, the ionic liquid/buffer biphasic system was used as bio-catalytic medium in catalytic hydrolysis of alliin to the sulfur-containing compounds by alliinase. The results showed that the enzyme activity was higher for 25% [BMIM]PF6/ buffer biphasic system than for pure buffer system but inhibited markedly by excess amount of [BMIM]PF6,and the thermal stability of the enzyme was enhanced. Using natural alliin as substrate,the Km of 0.591 mmol·L-1 and the Vmax of 0.316 mmol·L-1·min-1 were obtained for the enzyme catalytic reaction in [BMIM]PF6/buffer biphasic system,and the Vmax/Km ratio was about 2 fold of buffer monophasic system. In addition,in order to rising yield of essential oil,a combination technique of ionic liquid [BMIM]PF6,as bio-catalytic medium and extraction agent,and ultrasound-microwave-assisted was used for preparation and extraction of onion essential oil. The optimized conditions established were as follows:[BMIM]PF6 concentration 20%(vol),enzymatic time 2 h,ratio of raw material to liquid 1∶1.5,extraction temperature and time 25℃ and 50 s,and ultrasound-microwave power 150 W.Total 22 substances were identified in the onion essential oil prepared from fresh onion and 19 kinds of them sulfur-containing compounds by GC-MS analysis.To improve enzyme catalytic efficiency, the ionic liquid/buffer biphasic system was used as bio-catalytic medium in catalytic hydrolysis of alliin to the sulfur-containing compounds by alliinase. The results showed that the enzyme activity was higher for 25% [BMIM]PF6/ buffer biphasic system than for pure buffer system but inhibited markedly by excess amount of [BMIM]PF6,and the thermal stability of the enzyme was enhanced. Using natural alliin as substrate,the Km of 0.591 mmol·L-1 and the Vmax of 0.316 mmol·L-1·min-1 were obtained for the enzyme catalytic reaction in [BMIM]PF6/buffer biphasic system,and the Vmax/Km ratio was about 2 fold of buffer monophasic system. In addition,in order to rising yield of essential oil,a combination technique of ionic liquid [BMIM]PF6,as bio-catalytic medium and extraction agent,and ultrasound-microwave-assisted was used for preparation and extraction of onion essential oil. The optimized conditions established were as follows:[BMIM]PF6 concentration 20%(vol),enzymatic time 2 h,ratio of raw material to liquid 1∶1.5,extraction temperature and time 25℃ and 50 s,and ultrasound-microwave power 150 W.Total 22 substances were identified in the onion essential oil prepared from fresh onion and 19 kinds of them sulfur-containing compounds by GC-MS analysis.
    Adsorption behavior of U(Ⅵ) ions from aqueous solution on novel cross-linked magnetic chitosan beads
    HUANG Guolin1,CHEN Zhongsheng1,LIANG Xizhen1,SHI Jeffrey2
    2012, 63(3):  834-840.  doi:10.3969/j.issn.0438-1157.2012.03.023
    Abstract ( 1759 )   PDF (1052KB) ( 714 )  
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    The performance of a novel cross-linked magnetic chitosan(TTG-MCTS),which is coated with magnetic fluids and cross-linked with glutaraldehyde and thiourea,is investigated for the adsorption of U(Ⅵ) from aqueous solutions. Infrared spectra of chitosan before and after modification show that the coating is successful and the cross-linking process is effective. The energy dispersive spectroscopy(EDS) analysis before and after adsorption indicates that U(Ⅵ) is adsorbed successfully onto the TTG-MCTS. The influences of the pH of solution,the initial concentration of U(Ⅵ) ions and the contact time on the adsorption amounts are discussed,and appropriate process conditions for the adsorption of U(Ⅵ) are obtained. Experimental equilibrium data are obtained and modeled using classical Freundlich and Langmuir adsorption isotherms. The data fits to the Langmuir isotherm better,and the uptake of U(Ⅵ) is 161.3 mg·g-1. Two simplified models including pseudo-first order and pseudo-second order equations are selected to follow the adsorption process. The experimental data for the kinetics of adsorption are correlated well with the pseudo-second order equation.
    An improved knowledge evolution algorithm and its application to chemical process dynamic optimization
    PENG Xin,QI Rongbin,DU Wenli,QIAN Feng
    2012, 63(3):  841-850.  doi:10.3969/j.issn.0438-1157.2012.03.024
    Abstract ( 1920 )   PDF (984KB) ( 581 )  
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    The intelligent optimization algorithms have been widely used in solving dynamic optimization problems for their ability to converge to global optimum at a specific probability without being trapped in local optimums. However,the practical industrial application fields of such random mechanism-based algorithms are restricted due to their demerits,such as slow convergence and low searching efficiency.Therefore, an improved knowledge-based evolutionary algorithm structure was presented for improving the efficiency of intelligent optimization algorithms which were used to solve dynamic optimization problems. The structure included a discretization method of candidate solutions in time and control domains,the evolution of the repository,population evolution steered by knowledge. When applied to dynamic optimization problems of four typical chemical processes,such as batch reactor,which owned distinguishing control feature,this algorithm demonstrated its competitive optimal searching ability,meanwhile verifying its satisfying convergence efficiency by using a smaller scale of population guided by knowledge and consuming less computational cost.
    Multi-objective optimization of aromatic extraction process
    CHEN Bo,LIAO Zuwei,WANG Jingdai,YU Huanjun,YANG Yongrong
    2012, 63(3):  851-859.  doi:10.3969/j.issn.0438-1157.2012.03.025
    Abstract ( 2028 )   PDF (3426KB) ( 457 )  
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    Aromatic extraction is an important process of industrial aromatic production, its operation will affect greatly the overall efficiency of the aromatic complex. Product purity model and process energy consumption model are obtained based on simulation and response surface method, which are applied on the optimization of the process. A multi-objective optimization model is developed to maximize the product purity and minimize the energy consumption. An improved adaptive weighted sum method is proposed and used to solve the model. The results show that the new method can improve the efficiency without decreasing the uniformity of distribution of Pareto optimal solutions. The optimal operation parameters are given for different purity grades. The comparison between the results of optimization and the base case result shows that the optimal operation condition can increase product purity while decrease the energy consumption. The model and method proposed can effectively improve the accuracy of decision making in the operation optimization of aromatic extraction process.
    A new combined-electrode exciting-measuring mode for electrical capacitance tomography
    ZHANG Lifeng1,WANG Huaxiang2
    2012, 63(3):  860-865.  doi:10.3969/j.issn.0438-1157.2012.03.026
    Abstract ( 1600 )   PDF (1109KB) ( 634 )  
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    Electrical capacitance tomography (ECT) is a technique for two-phase flow measurement. The image reconstruction of ECT is a nonlinear and ill-posed inverse problem. The sensitivity distribution of ECT is inhomogeneous and only few measurements can be obtained, which causes the low quality of reconstructed images for the objects in the center. More measurements can be obtained by increasing the number of electrodes. But it will cause the decrease of measurement values and lower measurement accuracy. Under the condition of ensuring the measurement accuracy,the 24 combined-electrode sensor for ECT was proposed and two exciting-measuring modes were studied. The values and the dynamic range of measured capacitance values, the uniformity of sensitivity distribution and the reconstructed images of different flow regimes were compared with the conventional 12-electrode sensor. Simulation results showed that the sensitivity distribution was more uniform and the reconstructed images for the objects in the central locations were improved obviously by using 24 combined-electrode ECT sensor.
    Optimal melt index prediction based on ICPSO_WLSSVM algorithm for industrial propylene polymerization
    JIANG Huaqin, LIU Xinggao
    2012, 63(3):  866-872.  doi:10.3969/j.issn.0438-1157.2012.03.027
    Abstract ( 1905 )   PDF (635KB) ( 554 )  
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    Melt index (MI) is considered as one of the important quality variables of propylene (PP) polymerization, which determines the products specifications. Thus, a reliable estimation of MI is crucial in quality control. Addressing the deficiency of the particle swarm optimization (PSO) algorithm, whose particles are easy to sink into premature convergence and run into local optimization in the iterative process,this article introduces the selection strategy,the immune clone PSO(ICPSO) algorithm,which makes the particles of ICPSO maintain the diversity during the iterative process so as to overcome the premature convergence of PSO. The ICPSO was used to optimize the parameters of weighted least support vector machine (WLSSVM) to predict the melt index of polypropylene,so the optimized model ICPSO_WLSSVM was obtained. Researches on the optimized model were illustrated with the real plant of propylene polymerization, and the results showed that the proposed approach had great prediction accuracy and validity.
    Unsupervised fault detection for multimode processes using distance space statistics analysis
    MA Hehe,HU Yi,SHI Hongbo
    2012, 63(3):  873-880.  doi:10.3969/j.issn.0438-1157.2012.03.028
    Abstract ( 1879 )   PDF (2989KB) ( 625 )  
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    Industrial processes are often operated under different modes. However,most of the multivariate statistical process monitoring(MSPM) methods,such as principal component analysis(PCA) which are effective in single mode process,do not perform well in multimode process. A novel multimode fault detection approach named distance space statistics analysis (DSSA) was proposed. First, every sample was represented by the deviations of its k-nearest distances between itself and its neighbor in the training data. All the samples were mapped from the original space into the distance space by this way. Then, different order statistics of the distance samples in a moving window were calculated in the distance space. Finally, principal component analysis(PCA) was used to analyze the new statistics samples. The proposed method, PCA method and a multimode fault detection method using k-nearest neighbor rule (FD-kNN) were applied to the Tennessee Eastman (TE) benchmark process. The comparison of monitoring results showed that the proposed method was superior to the PCA and FD-kNN for fault detection of the multimode process.Industrial processes are often operated under different modes. However,most of the multivariate statistical process monitoring(MSPM) methods,such as principal component analysis(PCA) which are effective in single mode process,do not perform well in multimode process. A novel multimode fault detection approach named distance space statistics analysis (DSSA) was proposed. First, every sample was represented by the deviations of its k-nearest distances between itself and its neighbor in the training data. All the samples were mapped from the original space into the distance space by this way. Then, different order statistics of the distance samples in a moving window were calculated in the distance space. Finally, principal component analysis(PCA) was used to analyze the new statistics samples. The proposed method, PCA method and a multimode fault detection method using k-nearest neighbor rule (FD-kNN) were applied to the Tennessee Eastman (TE) benchmark process. The comparison of monitoring results showed that the proposed method was superior to the PCA and FD-kNN for fault detection of the multimode process.
    Manipulation margin and control performance analysis of chemical process under advanced process control
    XU Feng,LUO Xionglin
    2012, 63(3):  881-886.  doi:10.3969/j.issn.0438-1157.2012.03.029
    Abstract ( 2245 )   PDF (360KB) ( 474 )  
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    During chemical process design,the margin of manipulated variables must be determined not only for the possible change of process and equipment condition but also for the dynamic control of process control system,but its size cannot be too large in consideration of equipment cost. Now advanced process control, represented by predictive control provides a new method to improve process control performance. It is necessary to analyze the relationship between manipulation margin and control performance under advanced process control and find out the process design scheme to improve process control performance significantly at a lower cost of manipulation margin. So the mathematical description of solving the manipulation margin of chemical process under advanced process control is established. In advanced process control the linear model predictive control is used based on linear state space model, which is obtained through linearization on the steady nominal operating point,and the possible disturbances are also involved,then the problem is solved through dynamic optimization. The air flow rate margin of FCC regenerator was calculated as an example. When prediction horizon of predictive control was changed, different control performances were obtained and those corresponding manipulation margins were calculated. So the relationship between control performance and manipulation margin was found out.
    Screening and identification of phospholipase-producing strains and their applications
    JIANG Fangyan1, WANG Jinmei2, DAI Dazhang1, LI Chun1,2
    2012, 63(3):  887-893.  doi:10.3969/j.issn.0438-1157.2012.03.030
    Abstract ( 2256 )   PDF (562KB) ( 584 )  
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    Using soybean phospholipids as substrates, one strain which expressed phospholipase was screened out from the oil-rich soil sample by preliminary screening of plate cultivation and re-screening of shake flask fermentation. According to the morphological characteristics, physiochemical properties, and 16S rRNA sequences, the strain BIT-18 was identified as Pseudomonas fluorescens. Synthetic phosphatecholine (1-palmitoyl-2-oleoyl phosphatecholine) was used as substrate, then the fatty acid compositions of hydrolyzates were analyzed by gas chromatography, and the phospholipase from BIT-18 was determined as phospholipase B. This enzyme could not tolerate a high temperature. The optimal conditions for the enzymatic reaction were 25℃ and pH 6. 5, and low concentrations of metal ions were good for trigging its reaction. The phospholipase B from BIT-18 was used as catalyst for the degumming of soybean oil in a self-made batch reactor. The optimal conditions were phospholipase B dosage of 500 U·kg-1 and 2% water, and reaction at 40℃, pH 4.7 for 6 h. The residual phosphorus content of degummed oil decreased from 90.1 mg·kg-1 to 4.6 mg·kg-1, with the degumming rate as high as 94.9%, which showed a good application potential in the degumming of vegetable oils.Using soybean phospholipids as substrates, one strain which expressed phospholipase was screened out from the oil-rich soil sample by preliminary screening of plate cultivation and re-screening of shake flask fermentation. According to the morphological characteristics, physiochemical properties, and 16S rRNA sequences, the strain BIT-18 was identified as Pseudomonas fluorescens. Synthetic phosphatecholine (1-palmitoyl-2-oleoyl phosphatecholine) was used as substrate, then the fatty acid compositions of hydrolyzates were analyzed by gas chromatography, and the phospholipase from BIT-18 was determined as phospholipase B. This enzyme could not tolerate a high temperature. The optimal conditions for the enzymatic reaction were 25℃ and pH 6. 5, and low concentrations of metal ions were good for trigging its reaction. The phospholipase B from BIT-18 was used as catalyst for the degumming of soybean oil in a self-made batch reactor. The optimal conditions were phospholipase B dosage of 500 U·kg-1 and 2% water, and reaction at 40℃, pH 4.7 for 6 h. The residual phosphorus content of degummed oil decreased from 90.1 mg·kg-1 to 4.6 mg·kg-1, with the degumming rate as high as 94.9%, which showed a good application potential in the degumming of vegetable oils.
    A model of economy for overall process of CO2 capture and saline storage
    WANG Baoqun,LI Huiquan,BAO Weijun
    2012, 63(3):  894-903.  doi:10.3969/j.issn.0438-1157.2012.03.031
    Abstract ( 1360 )   PDF (772KB) ( 477 )  
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    Carbon capture and storage (CCS) consists of separation,compression, transportation and storage of CO2 from exhaust gas such as vent gases of coalfired power plant. CCS is considered to be the most effective choice for mitigating greenhouse gas of CO2 in the middle and short-term, and attracts more attention recently. Although CCS has been proved to be feasible in technology, it is still unsuitable for commercialization on a large scale due to high cost at present. Most models developed for cost estimation focused on individual process of CCS, especially on capture process. In this paper, definition formulas were given to calculate the total cost of CCS overall process and of emission cuts of CO2. Furthermore, a model economy is developed to estimate total capital and cost for MEA capture,compression, pipeline transportation and saline storage. The economic study for a case of 600 MW PC power plant is also carried out in the paper. The results show that,when CO2 recovery efficiency ranges from 70% to 99%,the total CCS cost for the case is 257—269 CNY·(t CO2)-1,and the cost for emission reduction of CO2 is 364.8—384.2 CNY·(t CO2)-1 respectively.
    Carbon deposition during reduction in chemical-looping combustion with Fe-based oxygen carriers
    XUAN Weiwei,ZHANG Jiansheng
    2012, 63(3):  904-909.  doi:10.3969/j.issn.0438-1157.2012.03.032
    Abstract ( 2104 )   PDF (1158KB) ( 657 )  
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    The iron-based oxygen carriers with Al2O3 as an inert prepared by mechanical mixing were studied on thermal gravimetric analyzer(TGA).Through the thermograms reduced by CH4,it was found that there was severe carbon deposition which even caused the mass curve to increase during reduction process. The concentration of reducing gas had a strong effect on the reaction rate as well as the degree of carbon deposition. At the same mass loss, higher concentration of the gas fuel tends to lead higher reaction rate while less carbon deposition. In addition, as the newly-generated carbon can be oxidized when introduced O2, the amount of CO2 during oxidation process can be applied to compare the level of carbon formation. With the redox cycles increased, the reaction was almost stable while the formation of carbon had a slightly downward tendency. Through analysis of the products with carbon deposition by X-ray diffraction and scanning electron microscope, there was Fe3C generated and the other part of C existed on the carrier in the form of carbon filaments.
    Feature of dioxin generation during gasification of solid waste containing high Cl in fluidized-bed
    ZHENG Jiao1,2,CHI Yong2,LI Jianxin1,WANG Yongchuan1,HU Changxing1
    2012, 63(3):  910-915.  doi:10.3969/j.issn.0438-1157.2012.03.033
    Abstract ( 2192 )   PDF (792KB) ( 498 )  
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    The generation of dioxin during recycling of solid waste is widely concerned. An experimental research on gasification of simulation garbage containing-high-PVC was carried out on a special designed integrated experimental platform for fluidized-bed gasification. The effects of PVC content and equivalent air ratio (ER) on feature of dioxins generation were discussed. The results show that when PVC content is 20% and ER decreases from 1.2 to 0.4, the yield and TEQ of dioxin produced per gram of PVC are decreased from 146.53 ng·g-1 and 20.71 ng I-TEQ·g-1 to 2.07 ng·g-1 and 0.31 ng I-TEQ·g-1, respectively. For the same ER 0.4 and PVC decreased from 20% to 1%, the yield and TEQ of dioxin produced per gram of PVC reduced from 23.54 ng·g-1 and 3.49 ng I-TEQ·g-1 to 2.07 ng·g-1 and 0.31 ng I-TEQ·g-1. That means that the risk of dioxin generation in gasification of the solid waste increases with PVC content, while low-air equivalent factor can suppress its generation.
    Effect of heat treatment on structural character and desulfurization capability of palygorskite
    ZHANG Xianlong,JIANG Weiping,WU Xueping,SHI Bowen,YANG Baojun,JIA Xiaobin,ZHANG Cuiping
    2012, 63(3):  916-923.  doi:10.3969/j.issn.0438-1157.2012.03.034
    Abstract ( 1931 )   PDF (499KB) ( 616 )  
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    Palygorskite as an excellent adsorbent material shows a predominant performance on the adsorption of small gaseous polar molecules, which can be remarkably improved by suitable thermal treatment. In this study, the SO2 removal from the flue gas is investigated with the palygorskite treated at different temperatures. The structural transformation of palygorskite desulfurizer during the heat treatment process was characterized by XRD,BET and TPD. A correlation between structural characteristics and desulfurization performance of palygorskite adsorbent was discussed. Results indicate that, as the heat treatment temperature increases, the micro-crystal structure of palygorskite displays significant step changes, which is suggested to be closely related to the removal of water in different forms from palygorskite surface. The adsorption capacity of SO2 on palygorskite first increases and then decreases as the heat treatment temperature increases. Based on these results, it can be deduced that the water adsorbed on the surface and that in the pores of palygorskite inhibit the adsorption of SO2, but the crystalline water is favorable for SO2 adsorption.
    Hydrogen production from sonolysis of alcohol solution
    DU Xuemin, ZHANG Zherui, DANG Zheng, BAI Bofeng
    2012, 63(3):  924-928.  doi:10.3969/j.issn.0438-1157.2012.03.035
    Abstract ( 2460 )   PDF (503KB) ( 465 )  
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    The removal of organic waste in water can be coupled with producing hydrogen by ultrasonic treatment. An experimental setup was designed and constructed to investigate sonolysis of alcohol solution. Methanol, ethanol and propanol solutions were tested and decomposed to hydrogen under low-frequency ultrasound(40 kHz,500 W).The effects of solution concentration,temperature,pH and addition of NaCl on hydrogen production/rate are studied. The results show that with rise of alcohol concentration rate of hydrogen production increases initially and then decreases. The augmentation of solution temperature can make position of the rate peak of hydrogen production shift from the point having greater concentration to that lower one. The addition of NaCl can make the hydrogen yield goes up. By contrast, there is no significant effect of solution pH on the rate. These results obtained in this paper could be used for optimum of the operation parameters in hydrogen production system from organic waste in water.
    Exergy analysis of rice husk gasification process in entrained-flow reactor
    ZHANG Yaning,ZHAO Yijun,SUN Shaozeng,LI Bingxi
    2012, 63(3):  929-934.  doi:10.3969/j.issn.0438-1157.2012.03.036
    Abstract ( 2734 )   PDF (782KB) ( 548 )  
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    Effect of air equivalence ratio ER on rice husk gasification in an entrained-flow reactor at different temperatures is analyzed using exergy concept. The results show that the contribution of gas component to exergy value is as follows:CO>H2>CH4>(N2,C2H4,CO2).With ER goes up the exergy value and its efficiency increase first and then decrease for product gas,however,the residual ratio and exergy efficiency decline first and then augment for unreacted carbon. At ER 0.25 and reactor temperature 1000℃,total exergy value and exergy efficiency of product gas are 7983.95 kJ·kg-1 and 54.35%,respectively,and at ER 0.28 and temperature 1000℃,the residual ratio and exergy efficiency of unreacted carbon are 24.82% and 21.49%,respectively. Raising temperature can lift exergy value and exergy efficiency of product gas, but reduce residual ratio and exergy efficiency of unreacted carbon.
    Comparative study on processes of simultaneous saccharification and fermentation with high solid concentration for cellulosic ethanol production
    CHANG Chun1,WANG Duo1,2,WANG Linfeng2,MA Xiaojian1
    2012, 63(3):  935-940.  doi:10.3969/j.issn.0438-1157.2012.03.037
    Abstract ( 2605 )   PDF (389KB) ( 694 )  
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    The effects of various simultaneous saccharification fermentation (SSF) technologies on ethanol yield from cellulose were investigated. Using steam-exploded corn stalks as raw materials, five SSF technologies, including traditional SSF, SSF combined with preliminary enzymatic hydrolysis,fed-batch SSF coupled with preliminary enzymatic hydrolysis,SSF united with preliminary enzymatic hydrolysis coupling with vacuum separation and fed-batch SSF associated with preliminary enzymatic hydrolysis coupling with vacuum separation,were used for decomposition of the stalks. By comparing the fermentation process with higher solid concentration including 15% (mass) and 30% (mass), it was found that the fed-batch SSF combined with preliminary enzymatic hydrolysis is an effective way for raising substrate concentration. However, higher substrate concentration may lead to decrease of final ethanol yield. Moreover, SSF coupled with vacuum separation can weaken the product inhibition, and increase the ethanol yield. The ethanol productivity by the fed-batch SSF associated with preliminary enzymatic hydrolysis coupling with vacuum separation is 0.40 g·L-1·h-1,the highest value obtained,indicating that this technology can be a potential new technology.
    Solubility and nucleation of benzylidene acetals in polypropylene
    ZHOU Jun,XIN Zhong
    2012, 63(3):  941-947.  doi:10.3969/j.issn.0438-1157.2012.03.038
    Abstract ( 2514 )   PDF (462KB) ( 766 )  
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    The effect of molecular structure of benzylidene acetals on their solubility and nucleation in isotactic polypropylene(iPP) was studied,selecting mono-p-methylbenzylidene sorbitol,di-(p-methylbenzylidene) sorbitol,tri-p-methylbenzylidene sorbitol and di-(p-methylbenzylidene) pentaerythritol as objects for study. Differential scanning calorimetry(DSC) results indicated that the polarity of benzylidene acetal decreased gradually with decreasing number of hydroxyl group and increasing number of benzylidene group,and the solubility of benzylidene acetals in iPP increased gradually. The saturated concentrations of these benzylidene acetals in iPP were 0.15%, 0.20%,0.80% and 4.00%,respectively. With this addition amount, the crystallization temperature of the nucleated iPP increased by 8.4,15.8,15.7 and 16.5℃,and the flexural modulus of nucleated iPP increased by 19. 9%,35. 8%,28. 7% and 18. 6%,and the haze of iPP decreased by 12.5%,46.2%,7.4% and -17.4%. Di- (p-methylbenzylidene) sorbitol was the best nucleating agent in these benzylidene acetals,which indicated that the effect of molecular structure of benzylidene acetals on their solubility and nucleation in iPP should be given consideration.The effect of molecular structure of benzylidene acetals on their solubility and nucleation in isotactic polypropylene(iPP) was studied,selecting mono-p-methylbenzylidene sorbitol,di-(p-methylbenzylidene) sorbitol,tri-p-methylbenzylidene sorbitol and di-(p-methylbenzylidene) pentaerythritol as objects for study. Differential scanning calorimetry(DSC) results indicated that the polarity of benzylidene acetal decreased gradually with decreasing number of hydroxyl group and increasing number of benzylidene group,and the solubility of benzylidene acetals in iPP increased gradually. The saturated concentrations of these benzylidene acetals in iPP were 0.15%, 0.20%,0.80% and 4.00%,respectively. With this addition amount, the crystallization temperature of the nucleated iPP increased by 8.4,15.8,15.7 and 16.5℃,and the flexural modulus of nucleated iPP increased by 19. 9%,35. 8%,28. 7% and 18. 6%,and the haze of iPP decreased by 12.5%,46.2%,7.4% and -17.4%. Di- (p-methylbenzylidene) sorbitol was the best nucleating agent in these benzylidene acetals,which indicated that the effect of molecular structure of benzylidene acetals on their solubility and nucleation in iPP should be given consideration.
    Preparation of TMC/TMPIP nanofiltration composite membrane with ultra-thin skin layer
    ZOU Kailun1,WANG Lihong2,ZHANG Lin1,CHEN Huanlin1,GAO Congjie1,3
    2012, 63(3):  948-954.  doi:10.3969/j.issn.0438-1157.2012.03.039
    Abstract ( 1965 )   PDF (2258KB) ( 748 )  
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    A nanofiltration (NF)composite membrane, with an ultra-thin skin layer, was prepared through interfacial polymerization on a polysulfone support with trimesoyl chloride (TMC)and a key aqueous monomer trimesoyl piperazine (TMPIP)hydrochloride with branched triimine structure, which was designed and synthesized based on the principle of interfacial polymerization of TMC and piperazine (PIP).Fourier transform infrared spectroscopy (FTIR)was combined with scanning electron microscope (SEM)to characterize the chemical composition and structure of the skin layer. The results showed that an ultra-thin poly(piperazineamide)skin layer, around 100 nm thick, was formed on the surface of support membrane. Compared with the performance of TMC/PIP composite membrane against PEG 200, the improved performance of TMC/TMPIP composite membrane was attributed to its high crosslinking and ultra-thin skin layer. The performance for aqueous solution of different salts was investigated, and it was found that the rejection and flux were both better than those of TMC/PIP composite membrane, with the same rejection order.
    Controllable synthesis of poly(acrylamide-co-vinylamine)with low amino groups
    YANG Jingjing, TANG Bingtao, ZHANG Shufen, BO Gu
    2012, 63(3):  955-961.  doi:10.3969/j.issn.0438-1157.2012.03.040
    Abstract ( 2140 )   PDF (544KB) ( 597 )  
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    The linear equation of controllable synthesis of poly (acrylamide-co-vinylamine)with low amino groups at low NaOH dosage was established. The influence factors, such as NaClO dosage, NaOH dosage, reaction time and temperature were investigated respectively. The results indicated that when the content of amino groups of poly(acrylamide-co-vinylamine)was below 50%, NaOH dosage was only as three times as that of polyacrylamide. The linear equation between NaClO dosage and content of amino groups of the product was also verified by elementary analysis. The results of GPC analysis showed that the average number molecular weight and PDI of the obtained poly(acrylamide-co-vinylamine)were approximate 1000—1800 and 1.6—2.0, respectively. This obtained linear equation would provide reaction conditions for the controllable synthesis of poly(acrylamide-co-vinylamine )with low amino groups.
    Genipin-crosslinked soybean protein/chitosan hydrogels for controlled release
    DUAN Lihong1,JIN Bei2,GAO Lijun2,FENG Zongcai3
    2012, 63(3):  962-969.  doi:10.3969/j.issn.0438-1157.2012.03.041
    Abstract ( 2069 )   PDF (1860KB) ( 759 )  
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    A novel hydrogel system (HD) composed of soybean (SB) protein and chitosan(CS) blended with naturally non-toxic genipin was developed for controlling theophylline delivery. Additionally, the release profile of a model drug (theophylline) from test hydrogels was investigated in simulated gastric and intestinal fluid as well as pH7.4 buffer. The surface morphology and structure of composite chitosan-based hydrogels were characterized by infrared spectrophotometry and scanning electron microscopy as well as 1H NMR spectra. These results showed obvious crosslinking systems for soybean protein and chitosan by genipin in the composite hydrogels. These composite hydrogels had retained compact sheets. All hydrogels swelled in the simulated gastric and intestinal solution as well as pH7.4 buffer, but the swelling ratio of the hydrogels in the simulated gastric medium was low. In addition, the amount of theophylline released in the simulated gastric medium (pH1.2) was lower than that in intestinal fluid (pH6.8) and pH7.4 buffer. These composite hydrogels were found to be pH-sensitive. The controlled release of theophylline was realized in 120 h. Therefore, the genipin-corsslinked composite hydrogel could be a suitable carrier for site-specific drug delivery in the intestine.
    Preparation and drug release of pH and temperature sensitive MCM-41/P(AA-co-NIPAAm)
    CAO Yuan,ZHANG Li,WANG Xiao,XU Yanqin
    2012, 63(3):  970-977.  doi:10.3969/j.issn.0438-1157.2012.03.042
    Abstract ( 2707 )   PDF (467KB) ( 842 )  
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    Mesoporous silica materials with such advantages as high surface area, large pore volume, uniform porosity, stable aqueous dispersion, excellent biocompatibility,non-toxic properties,and the capability to be functionalized with different organic groups could be prepared. Such materials have the basic conditions for drug delivery due to the above advantages. In addition, in biomedical applications, smart intelligent hydrogels can be used for encapsulation of enzymes, controlled drug release, etc. and is also a good drug-carrier material. Smart intelligent hydrogels composites with mesoporous materials with the characteristics of the two materials can be made, and have a broad prospect in application. In this paper,mesoporous molecular sieve(MCM-41) was synthesized by the microwave method,and then composite material MCM-41/P(AA-co-NIPAAm) sensitive to pH value and temperature was synthesized by polymerization of MCM-41 with acrylic acid(AA) and N-isopropylacrylamide(NIPAAm) in situ. The materials were characterized by X-ray diffraction(XRD),nitrogen adsorption-desorption,Fourier transform infrared spectroscopy(FT-IR),and thermogravimetry analysis(TGA).It was found that a new polymer composite was synthesized.The polymer composite exhibited good sensitivities to both temperature and pH. Selecting hydrochlorothiazide as a model drug, the properties of drug loading and release behavior under different pH values and different temperatures were studied with ultraviolet spectrophotometry.  The results showed that composite material MCM-41/P(AA-co-NIPAAm) had a high hydrochlorothiazide storage capacity of 45.8% and hydrochlorothiazide molecules were controlled released from the composite material by adjusting the temperature and pH of the environment. The material released drug faster in simulated intestinal fluid(pH=6.8).When the temperature was higher than 32℃,the release amount would decrease,and when the temperature was lower than 32℃,the release amount would increase significantly. Therefore, this novel MCM-41/P(AA-co-NIPAAm) composite has a potential application to targeted intestinal drug release.Mesoporous silica materials with such advantages as high surface area, large pore volume, uniform porosity, stable aqueous dispersion, excellent biocompatibility,non-toxic properties,and the capability to be functionalized with different organic groups could be prepared. Such materials have the basic conditions for drug delivery due to the above advantages. In addition, in biomedical applications, smart intelligent hydrogels can be used for encapsulation of enzymes, controlled drug release, etc. and is also a good drug-carrier material. Smart intelligent hydrogels composites with mesoporous materials with the characteristics of the two materials can be made, and have a broad prospect in application. In this paper,mesoporous molecular sieve(MCM-41) was synthesized by the microwave method,and then composite material MCM-41/P(AA-co-NIPAAm) sensitive to pH value and temperature was synthesized by polymerization of MCM-41 with acrylic acid(AA) and N-isopropylacrylamide(NIPAAm) in situ. The materials were characterized by X-ray diffraction(XRD),nitrogen adsorption-desorption,Fourier transform infrared spectroscopy(FT-IR),and thermogravimetry analysis(TGA).It was found that a new polymer composite was synthesized.The polymer composite exhibited good sensitivities to both temperature and pH. Selecting hydrochlorothiazide as a model drug, the properties of drug loading and release behavior under different pH values and different temperatures were studied with ultraviolet spectrophotometry.  The results showed that composite material MCM-41/P(AA-co-NIPAAm) had a high hydrochlorothiazide storage capacity of 45.8% and hydrochlorothiazide molecules were controlled released from the composite material by adjusting the temperature and pH of the environment. The material released drug faster in simulated intestinal fluid(pH=6.8).When the temperature was higher than 32℃,the release amount would decrease,and when the temperature was lower than 32℃,the release amount would increase significantly. Therefore, this novel MCM-41/P(AA-co-NIPAAm) composite has a potential application to targeted intestinal drug release.
    Optimization of additives of intumescent fire resistant coating for steel structure by response surface methodology
    WANG Guojian1,2,WANG Yilong2
    2012, 63(3):  978-984.  doi:10.3969/j.issn.0438-1157.2012.03.043
    Abstract ( 1762 )   PDF (2645KB) ( 577 )  
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    Response surface methodology (RSM) is a statistical method to forecast response values by designing logical experiment programs, adopting quadratic polynomial equation to associate and optimize the relationships between factors and response values. In this work, RSM was applied to optimizing the most common fire resistant additives (APP-MEL-PER) of intumescent fire resistant coating for steel structure. The influence of fire resistant additives and their mutual effects on the fireproof properties of fire resistant coating were discussed. Moreover, relevant mathematical forecast model was also built. The analysis of variance showed that 98.33% response value could be explained by the quadratic polynomial created. The error rate of modeling prediction was only 0.48%. These results proved that this modeling was efficient and precise. The equilibrium temperatures of the optimized sample decreased by 12℃. Besides, the optimized sample had a more uniform foam structure and well-distributed cell sizes,which resulted in better fireproof performance. The optimization for fire resistant coating by response surface methodology was feasible and successful.
    Influence of flow field in extrusion dies on orientation and distribution of glass fiber
    WANG Quanjie,HUANG Hanxiong,CAI Zilin
    2012, 63(3):  985-990.  doi:10.3969/j.issn.0438-1157.2012.03.044
    Abstract ( 2042 )   PDF (4624KB) ( 588 )  
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    In the current work,flow fields in both straight and divergent dies were analyzed,and the circumferential stretch rate in the divergent channel was derived. The glass fiber orientation and distribution across the thickness of samples extruded from both dies at two flow rates were studied.  The formation mechanism of aforementioned glass fiber orientation and distribution was explained by using the distribution of shear and stretch strain rates. The results showed that most of the glass fibers were aligned in the flow direction in the samples extruded from the straight die. A five-layered structure, including two skin layers, two sub-skin layers,and a core layer,formed across the thickness of the samples extruded from the divergent die. It was first found that the fibers exhibited a “W” type alignment in the core layer. It was also demonstrated that the glass fiber alignments were affected more remarkably by the strain rate than the strain.In the current work,flow fields in both straight and divergent dies were analyzed,and the circumferential stretch rate in the divergent channel was derived. The glass fiber orientation and distribution across the thickness of samples extruded from both dies at two flow rates were studied.  The formation mechanism of aforementioned glass fiber orientation and distribution was explained by using the distribution of shear and stretch strain rates. The results showed that most of the glass fibers were aligned in the flow direction in the samples extruded from the straight die. A five-layered structure, including two skin layers, two sub-skin layers,and a core layer,formed across the thickness of the samples extruded from the divergent die. It was first found that the fibers exhibited a “W” type alignment in the core layer. It was also demonstrated that the glass fiber alignments were affected more remarkably by the strain rate than the strain.
    Recovery of titanium from titanium-bearing blast furnace slag by ammonium sulfate melting method
    WANG Sijia, ZHANG Yue, XUE Xiangxin, YANG He
    2012, 63(3):  991-995.  doi:10.3969/j.issn.0438-1157.2012.03.045
    Abstract ( 2498 )   PDF (364KB) ( 884 )  
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    A melting reaction process was developed to transform the titanium in titanium-bearing blast furnace slag into water-soluble one, such as TiOSO4 by the treatment with ammonium sulfate and potassium bisulfate, to recover titanium. The effects of quantities of ammonium sulfate and potassium bisulfate added, reaction temperature and holding time on the recovery rate of titanium were investigated systemically. The experimental results showed that reaction temperature and holding time have a great impact on the recovery of titanium. The recovery rate of titanium was improved with an increase of reaction temperature and holding time. The optimum conditions of titanium recovery from titanium-bearing blast furnace slag were as follows: the mass ratio of slag to ammonium sulfate 1∶6, reaction temperature 350℃, and holding time 27 min. Under such conditions the recovery rate of titanium was up to 91. 7% and the evaporation loss rate of nitrogen from (NH4)2SO4 was 81.5%. The residue obtained after recovery of titanium was mainly composed of CaSO4·H2O, CaSO4·0.5H2O, SiO2, a small amount of CaTiO3 and Ca2Al2SiO7. This study promises significant economic benefits for smelting enterprise.