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SCI和EI收录∣中国化工学会会刊
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Table of Content
28 February 2013, Volume 21 Issue 1
    Performance of V2O5-WO3-MoO3/TiO2 Catalyst for Selective Catalytic Reduction of NOx by NH3
    GAO Yan, LUAN Tao, LV Tao, CHENG Kai, XU Hongming
    2013, 21(1):  1-7.  doi:10.1016/S1004-9541(13)60434-6
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    The V2O5-WO3-MoO3/TiO2 honeycomb catalyst was prepared with industrial grade chemicals. The structural and physico-chemical properties were analyzed with X-ray diffraction (XRD), scanning electron micrograph (SEM) and mercury porosimetry. The NOx conversion and durability were investigated on a pilot plant test set under the actual operational conditions of a coal fired boiler. The catalyst monolith had good formability with mass percentage of V:W:Mo:TiO2:fiber glass 1: 4.5:4.5:72:18. Vanadium, tungsten and molybdenum species were highly dispersed on anatase TiO2 without causing the transformation of anatase TiO2 to rutile by calcining under a current of air at 450 °C for 4.5 h, but there were some degrees of crystal distortion. The catalyst particle sizes were almost uniform with close pile-up and the pore structure was regular with complete macro-pore formation and large specific surface area. The NOx conversion was sensitive to temperature but nearly insensitive to NH3. The catalyst showed strong adaptability to NOx concentration with activity above 80% in the range of 615-1640 mg·m-3. Within the range of 720-8640 h continuous operation, the NOx conversion dropped at a rate of about 1% reduction per 600 h.
    CATALYSIS, KINETICS AND REACTORS
    Synthesis of Diphenyl Carbonate over the Magnetic Catalysts Pd/La1-xPbxMnO3 (x=0.2-0.7)
    LU Wei, DU Zhiping, YUAN Hua, TIAN Qifeng, WU Yuanxin
    2013, 21(1):  8-13.  doi:10.1016/S1004-9541(13)60435-8
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    The magnetic perovskite-supported palladium catalysts Pd/La1-xPbxMnO3 (x=0.2-0.7) were prepared and used for the oxidative carbonylation of phenol to diphenyl carbonate. The synthesized catalysts were characterized by the X-ray diffraction (XRD), surface area measurement BET, vibration sample magnetometer (VSM) and temperature-programmed reduction (TPR). The experimental results demonstrated that the magnetic Pd/La1-xPbxMnO3 (x=0.4-0.5) obtain relative better catalytic activity. It can be explained by higher concentration of oxygen vacancies, larger amount and better mobility of lattice oxygen of their support. Furthermore, these samples possess sufficient saturated magnetization. Thus, Pd/La1-xPbxMnO3 (x=0.4-0.5) may be suitable for operation in the magnetically stabilized bed reactor.
    FLUID DYNAMICS AND TRANSPORT PHENOMENA
    Single-jet Spray Mixing with a Confined Crossflow
    SUN Huijuan, BAI Bofeng, YAN Junjie, ZHANG Haibin
    2013, 21(1):  14-24.  doi:10.1016/S1004-9541(13)60436-X
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    In order to achieve uniform mixing between spray droplets and crossflow, cold-model experiment of a hollow-cone water spray in an air crossflow is investigated via a numerical simulation. The simulation cases are designed by using the orthogonal design method. The Eulerian-Lagrangian formulation is employed for modeling the droplets-crossflow two-phase flow while the realizable k-ε turbulence model is used to describe the turbulence. A new index, mixedness quality, is proposed to assess the overall mixing of the droplets in the crossflow. The simulation results demonstrate that the counter-rotating vortex pair (CVP) imposes a more significant impact on the spatial distribution than on the size distribution of the droplets. Pairs of CVP with smaller scales are preferable for achieving a better mixing. The influencing factors are listed in the following order in terms of the degree of their impact from the greatest to the least: the Sauter diameter of the initial droplets, the mixing tube diameter, the spray angle, the velocity of the inlet crossflow, and the vertical velocity of the initial droplets. A moderate droplet diameter, a smaller tube diameter, a moderate spray angle, a greater crossflow velocity and a moderate vertical velocity of the droplet are favorable for achieving a higher mixedness quality of the jet spray in a confined crossflow.
    Effects of Gas Temperature Fluctuation on the Soot Formation Reactions
    CHEN Ying, ZHANG Jian
    2013, 21(1):  25-30.  doi:10.1016/S1004-9541(13)60437-1
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    The effects of gas temperature fluctuations on soot formation and oxidation reactions are investigated numerically in a reacting flow. The instantaneous variations of soot mass fraction with time are obtained under the time-averaged gas temperature of 1500-1700 K. The simulation results show that the gas temperature fluctuation has obvious influence on the instantaneous processes of soot formation and oxidation. Within the present range of gas temperature, the gas temperature fluctuation results in generally lower soot mass fraction comparing to that without gas temperature fluctuation. The increase in the fluctuation amplitude of gas temperature leads to decrease in time-averaged soot mass fraction and increase in time-averaged soot particle number density.
    Extraction of Theanine from Waste Liquid of Tea Polyphenol Production in Aqueous Two-phase Systems with Cationic and Anionic Surfactants
    ZHANG Junwei, WANG Yan, PENG Qijun
    2013, 21(1):  31-36.  doi:10.1016/S1004-9541(13)60438-3
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    Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactant two-phase system (ASTP) with cationic surfactant (CTAB) and anionic surfactant (SDS). Results indicate that the region of ASTP is narrow and there is only a two-phase region of cationic surfactant. The increase in concentrations of NaBr and Na2SO4 are beneficial to the formation of ASTP. Theanine concentration in the bottom phase increases with increasing concentration of theanine, whereas the partition coefficient and extraction rate only change a little when the concentration of theanine is above 0.2 g·L-1. With the increase of SDS concentration, the phase ratio and the partition coefficient decrease, while the extraction efficiency of theanine increases and the concentration of theanine changes a little in the range from 2.4/7.5 to 2.8/7.2 for SDS/CTAB ratio. The temperature has a notable effect on the concentration of theanine in the bottom phase, partition coefficient and extraction rate of theanine. The increase of waste liquid decreases the phase ratio, increases the concentration and extraction rate of theanine in the bottom phase, since the protein and the saccharide enter the bottom phase with theanine.
    High-yield Synthesis of Nanohybrid Shish-kebab Polyethylene-carbon Nanotube Structure
    CUI Chaojie, QIAN Weizhong, ZHAO Mengqiang, XU Guanghui, NIE Jingqi, JIA Xilai, WEI Fei
    2013, 21(1):  37-43.  doi:10.1016/S1004-9541(13)60439-5
    Abstract ( )   PDF (1004KB) ( )  
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    We report a novel method to prepare nanohybrid shish-kebab (NHSK) structure of polyethylene (PE) and carbon nanotube (CNT). Pristine CNTs without surface modification with high concentration was effectively dispersed in xylene solution by a simple shearing method, which induces the quick crystallization of PE in xylene to form a novel NHSK structure with more dense and smaller PE kebab on CNT axis. The flocculated NHSK product was transferred quickly from the xylene solution to the ethanol solution, in order to shorten the preparation time. The freeze-drying method was used in vacuum instead of high-temperature drying to avoid the aggregation of NHSK product. These improvements allow the formation of NHSK with an absolute yield of 200 mg·h-1, which is 2000 folds of that reported previously. It is favorable to apply this structured material in high performance nanocomposite, by improving the compatibility of CNTs in polymer and the interfacial force between CNTs and polymer.
    PROCESS SYSTEMS ENGINEERING
    A New Extension Theory-based Production Operation Method in Industrial Process
    XU Yuan, ZHU Qunxiong
    2013, 21(1):  44-54.  doi:10.1016/S1004-9541(13)60440-1
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    To explore the problems of dynamic change in production demand and operating contradiction in production process, a new extension theory-based production operation method is proposed. The core is the demand requisition, contradiction resolution and operation classification. For the demand requisition, the deep and comprehensive demand elements are collected by the conjugating analysis. For the contradiction resolution, the conflict between the demand and operating elements are solved by the extension reasoning, extension transformation and consistency judgment. For the operating classification, the operating importance among the operating elements is calculated by the extension clustering so as to guide the production operation and ensure the production safety. Through the actual application in the cascade reaction process of high-density polyethylene (HDPE) of a chemical plant, cases study and comparison show that the proposed extension theory-based production operation method is significantly better than the traditional experience-based operation method in actual production process, which exploits a new way to the research on the production operating methods for industrial process.
    Solution of Chemical Dynamic Optimization Using the Simultaneous Strategies
    LIU Xinggao, CHEN Long, HU Yunqing
    2013, 21(1):  55-63.  doi:10.1016/S1004-9541(13)60441-3
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    An approach of simultaneous strategies with two novel techniques is proposed to improve the solution accuracy of chemical dynamic optimization problems. The first technique is to handle constraints on control variables based on the finite-element collocation so as to control the approximation error for discrete optimal problems, where a set of control constraints at element knots are integrated with the procedure for optimization leading to a significant gain in the accuracy of the simultaneous strategies. The second technique is to make the mesh refinement more feasible and reliable by introducing length constraints and guideline in designing appropriate element length boundaries, so that the proposed approach becomes more efficient in adjusting elements to track optimal control profile breakpoints and ensure accurate state and control profiles. Four classic benchmarks of dynamic optimization problems are used as illustrations, and the proposed approach is compared with literature reports. The research results reveal that the proposed approach is preferable in improving the solution accuracy of chemical dynamic optimization problem.
    Novel Control Vector Parameterization Method with Differential Evolution Algorithm and Its Application in Dynamic Optimization of Chemical Processes
    SUN Fan, ZHONG Weimin, CHENG Hui, QIAN Feng
    2013, 21(1):  64-71.  doi:10.1016/S1004-9541(13)60442-5
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    Two general approaches are adopted in solving dynamic optimization problems in chemical processes, namely, the analytical and numerical methods. The numerical method, which is based on heuristic algorithms, has been widely used. An approach that combines differential evolution (DE) algorithm and control vector parameterization (CVP) is proposed in this paper. In the proposed CVP, control variables are approximated with polynomials based on state variables and time in the entire time interval. Region reduction strategy is used in DE to reduce the width of the search region, which improves the computing efficiency. The results of the case studies demonstrate the feasibility and efficiency of the proposed methods.
    Numerical Investigation on Effect of Vapor Split Ratio to Performance and Operability for Dividing Wall Column
    Laleh Torab Maralani, YUAN Xigang, LUO Yiqing, GONG Chao, YU Guocong
    2013, 21(1):  72-78.  doi:10.1016/S1004-9541(13)60443-7
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    Operability problem of dividing wall column (DWC) raised by vapor split was investigated by numerically analyzing four cases defined by different compositions of a three-component mixture. DWCs were firstly designed for each case by optimizing the vapor split to the two sides of the dividing wall, and then their feasibilities and total annual costs in operation were evaluated against different vapor split ratios. The analysis on the operability of the DWC for four cases was made based on two scenarios: (1) vapor split is shifted by the vapor resistance difference between the column sections in the two sides of the dividing wall and (2) the feed composition is changed. It was demonstrated that the positioning of the dividing wall and the decision on the vapor split may affect significantly the operability of a DWC.
    Three Stage Equilibrium Model for Coal Gasification in Entrained Flow Gasifiers Based on Aspen Plus
    KONG Xiangdong, ZHONG Weimin, DU Wenli, QIAN Feng
    2013, 21(1):  79-84.  doi:10.1016/S1004-9541(13)60444-9
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    A three stage equilibrium model is developed for coal gasification in the Texaco type coal gasifiers based on Aspen Plus to calculate the composition of product gas, carbon conversion, and gasification temperature. The model is divided into three stages including pyrolysis and combustion stage, char gas reaction stage, and gas phase reaction stage. Part of the water produced in the pyrolysis and combustion stage is assumed to be involved in the second stage to react with the unburned carbon. Carbon conversion is then estimated in the second stage by steam participation ratio expressed as a function of temperature. And the gas product compositions are calculated from gas phase reactions in the third stage. The simulation results are consistent with published experimental data.
    ENERGY, RESOURCES AND ENVIRONMENTAL TECHNOLOGY
    Measurement of Two Phase Flow in Porous Medium Using High-resolution Magnetic Resonance Imaging
    JIANG Lanlan, SONG Yongchen, LIU Yu, YANG Mingjun, ZHU Ningjun, WANG Xiaojing, DOU Binlin
    2013, 21(1):  85-93.  doi:10.1016/S1004-9541(13)60445-0
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    Measurement of two phase flow in porous medium for sequestration was carried out using high-resolution magnetic resonance imaging (MRI) technique. The porous medium was a packed bed of glass beads. Spin echo multi sequence was used to measure the distribution of CO2 and water in the porous medium. The intensity images show that the fluid distribution is non-uniform due to its viscosity and pore structure of porous medium. The velocity distribution of fluids is calculated from the saturation of water and porosity of porous medium. The experimental results show that fluid velocities vary with time and position. The capillary dispersion rate donated the effects of capillary, which was largest at water saturations of 0.45. The displacement process is different between in BZ-02 and BZ-2. The final water residual saturation depends on permeability and porosity.
    Number Concentration of Cylindrical Particles in a Fluidized Bed
    CAI Jie, ZHAO Xiaobao, LI Qihe, YUAN Zhulin
    2013, 21(1):  94-103.  doi:10.1016/S1004-9541(13)60446-2
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    In this study, a three-dimensional model based on RANS, slender-body theory and Newton-Euler dynamics is established to study the number concentration, one of the most important fluidization characteristics of cylindrical particles. Also, the effects of interaction between cylindrical particles are taken into account by introducing the rigid collision dynamics. To validate the model, the fluidization experiments of cylindrical particles in a cold-state fluidized bed are carried out. The number concentration characteristics of cylindrical particles are obtained from computational fluid dynamics (CFD) simulation. It is found that cylindrical particles arriving at the exit of the riser the earliest come from the near-wall regions, the horizontal transfer of so many cylindrical particles from the radial centre regions to the near-wall regions is evident. Meanwhile, there is no distinct relationship between the number concentration and inlet wind velocity.
    RESEARCH NOTES
    Influence of Nonionic Surfactant Addition on Drag Reduction of Water Based Nanofluid in a Small Diameter Pipe
    Michał Drzazga, Andrzej Gierczycki, Grzegorz Dzido, Marcin Lemanowicz
    2013, 21(1):  104-108.  doi:10.1016/S1004-9541(13)60447-4
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    The goal of this research was to determine the impact of nonionic surfactants on drag reduction effect in water and metal oxide nanofluid. Two nonionic surfactants (Rokacet O7 and Rokanol K7) and copper(II) oxide water-based nanofluid were examined. Friction factors in a 4 mm diameter pipe for the Reynolds number between 8000 and 50000 were determined. Results showed that addition of nonionic surfactants caused the decrease of friction factor in water and nanofluid. The drag reduction effect was similar in both cases. Presence of nanoparticles in the system has no great influence on drag reduction effect.