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05 September 2014, Volume 65 Issue 9
    CIESC Journal(HUAGONG XUEBAO)Vol.65 No.9 May 2014
    2014, 65(9):  0-0. 
    Abstract ( 230 )   PDF (1658KB) ( 338 )  
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    Prediction of VLE data for system containing α-pinene by UNIFAC model
    FENG Qi, SUN Lixia, TONG Zhangfa
    2014, 65(9):  3309-3316.  doi:10.3969/j.issn.0438-1157.2014.09.001
    Abstract ( 564 )   PDF (2821KB) ( 450 )  
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    α-Pinene has a special bicyclo and C=C structure. In order to predict the vapor-liquid equilibrium (VLE) data for the system containing α-pinene more accurately, α-pinene was divided into one bicyclo[3.1.1]hept-2-ene and three CH3 according to the theory of UNIFAC model. With the correlation of VLE data for the binary system containing α-pinene, group interaction parameters for bicyclo[3.1.1]hept-2-ene with CH3, C=C, ACH and ACCH3 were obtained, which expands the application of the UNIFAC model. Comparing with the original UNIFAC model using only CH3, C=C, ACH and ACCH3 to predict VLE data of ternary system containing α-pinene, the average deviation of vapor composition and temperature from the prediction of VLE data by new group parameters are smaller than that by the original group parameters, indicating that the new group for α-pinene is more reasonable.
    Thermodynamics computational simulation of 4-nitrophenylarsonic acid synthesis
    LÜ Le, YANG Zuoguo, ZHAO Ying
    2014, 65(9):  3317-3322.  doi:10.3969/j.issn.0438-1157.2014.09.002
    Abstract ( 571 )   PDF (955KB) ( 356 )  
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    The structures of the reactants and products of synthesis of 4-nitrophenylarsonic acid were studied by using the B3LYP method of density functional theory. Then the structures were optimized by computational analysis. The changes in reaction enthalpy, Gibbs free energy and equilibrium constant for the primary and side reaction were calculated and analyzed with the basic thermodynamic data obtained from vibration frequency analysis. The simulation results show that the primary reaction process is exothermic and irreversible, the enthalpy change is -15.0 kJ·mol-1, the Gibbs free energy change is 39.7 kJ·mol-1. The side reaction process is endothermic and irreversible, the enthalpy change is 10.0 kJ·mol-1, the Gibbs free energy change is 45.2 kJ·mol-1. The computational studies on thermodynamics of 4-nitrophenylarsonic acid synthesis can provide the theoretical guidance to the reaction process condition control.
    Numerical simulation of mixing characteristics of trace sample and bed material in micro fluidized bed reaction analyzer
    YANG Xu, LIU Yaning, YU Jian, JIANG Fuming, HAN Yongsheng, XU Guangwen, GE Wei
    2014, 65(9):  3323-3330.  doi:10.3969/j.issn.0438-1157.2014.09.003
    Abstract ( 831 )   PDF (4935KB) ( 552 )  
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    The micro fluidized bed reaction analyzer (MFBRA) developed by Institute of Process Engineering, Chinese Academy of Sciences has isothermal differential characteristics and is suitable for gas-solids fast reaction analysis, including the measurement of reaction rate and kinetic parameters. The instantaneously intensive particle mixing between trace sample in milligrams and high-temperature fluidized material is the essential condition to keep isothermal differential characteristics of the micro fluidized bed reactor. Therefore a three-dimensional numerical simulation based on the Eulerian multi-fluid model was performed for the micro fluidized bed connected with different gas jet structures. The instantaneous flow structures and quantitative mixing characterizations for different injector structures and locations were obtained. Experiments were conducted through measurements using high speed camera to capture the instantaneous solids flow pictures in the bed. Comparison revealed good qualitative agreement between experiment and simulation. The simulation results suggested that the injector should avoid the bending angle that confronted the injected gas with the fluidizing gas or left the trace sample in the injector.
    Laser induced fluorescence technique for measuring liquid distribution in structured packing
    ZHANG Huishu, YUAN Xigang, KALBASSI Mohammad Ali
    2014, 65(9):  3331-3339.  doi:10.3969/j.issn.0438-1157.2014.09.004
    Abstract ( 316 )   PDF (6441KB) ( 372 )  
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    Laser induced fluorescence (LIF) technique was used to perform experiments of liquid distribution in corrugated structured Perspex packing. The technique was based on continuous detection of intensity of fluorescence change. In order to validate the feasibility of this method, liquid distributions of three systems in 750Y corrugated structured packing were investigated. The LIF technique was very useful not only for the identification of liquid distribution, but also for quantification of liquid film thickness and liquid hold up on the structured packing surface. Both interfacial tension and viscosity of experimental systems could affect liquid distribution but interfacial tension's influence was more remarkable.
    Chaotic mixing intensified by rigid-flexible coupling impeller
    LIU Zuohua, SUN Ruixiang, WANG Yundong, TAO Changyuan, LIU Renlong
    2014, 65(9):  3340-3349.  doi:10.3969/j.issn.0438-1157.2014.09.005
    Abstract ( 817 )   PDF (9365KB) ( 396 )  
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    Rational design of impellers in stirred vessels for strengthening the fluid flow and mixing is an important way to achieve efficient and energy-saving mixing. Rigid-flexible coupling impeller can be designed by combination of flexible body and rigid body, possessing multiple-body motion behavior. In this study, CFD simulation and PIV flow visualization were comparatively employed to analyze the difference between rigid impeller and rigid-flexible coupling impeller for fluid flow structure and mixing performance. Results showed that, compared with rigid impeller system, velocity decaying rate was reduced by 25% with rigid-flexible coupling impeller system, because it had the ability to intensify the input energy transportation by flexible part and distribute the input energy in flow field structure effectively. The streamline of the fluid stirred by rigid PBT-6 impeller and rigid RDT-6 impeller had obviously periodic attractor with fractal dimension 1.9046 and 1.9138 respectively. Rigid-flexible coupling impellers could intensify chaotic mixing of fluid and regulate the fractal dimension of flow field structure. The streamline of fluid stirred by flexible RDT-6 impeller had quasi-periodic attractors with fractal dimension of 1.9337, while the fractal dimension of chaotic attractor was 1.9545 with flexible PBT-6 impeller. It suggests that the flexible impeller could regulate multi-scale structure of the flow field by changing streamline attractor to intensify the chaotic mixing and achieve energy efficient operation.
    Impact of gas distributor configuration on hydrodynamics in bubble column with pipe internals
    GUAN Xiaoping, LI Zhaoqi, ZHAO Yuanfang, WANG Lijun, CHENG Youwei, LI Xi
    2014, 65(9):  3350-3356.  doi:10.3969/j.issn.0438-1157.2014.09.006
    Abstract ( 344 )   PDF (657KB) ( 271 )  
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    Gas holdup and liquid axial velocity profile were measured in a large scale bubble column with tube bundle internals with four different types of gas distributor configuration and were compared with results in the bubble column without internals. Gas distribution type directly determined gas holdup and liquid axial velocity profile in the bubble column with internals. With central distribution, gas holdup and liquid axial velocity profile showed much steeper than those in the bubble column without internals. With annulus or near wall distribution, they presented saddle profile, while with uniform distribution, both of them showed more flat than those in the bubble column without internals. The influence of gas distributor was local in the bubble column without internals and the well-developed region occupied a major part of the column, however, its impact was global in the bubble column with internals and the initial distributions of gas holdup and liquid velocity determined their distributions in the whole column. It was difficult to observe the existence of well-developed region in the bubble column with internals and therefore, designing gas distributor is more meaningful than the bubble column without internals.
    Coupled heat and moisture transfer in diatomite-based humidity control material
    ZHENG Jiayi, CHEN Zhenqian
    2014, 65(9):  3357-3365.  doi:10.3969/j.issn.0438-1157.2014.09.007
    Abstract ( 265 )   PDF (2484KB) ( 264 )  
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    A 1-D mathematical model is established for diatomite-based humidity control materials (DBHCM), to simulate the coupled heat and moisture migration process at different porosities, different ambient temperatures and different ambient relative humidities. The humidity control performance of DBHCM is tested and surfaces of DBHCM are characterized by micrograph. The results show that with the decrease of porosity, the amounts of adsorption and desorption increase, ambient temperature does not significantly influence the coupled heat and moisture migration process, and the effect of ambient temperature (the maximum deviation is 20℃) on the adsorption and desorption of DBHCM is about 10%. Better humidity control performance demands smaller pore diameter and larger quantity of small pores. The experimental results and the predictions of humidity control performance of DBHCM, as well as the micrograph representation of pore structures of DBHCM agree well with each others, which can fully verify the rationality of the mathematical model.
    Analysis of thermodynamic losses of heat transfer process in large-scale LT-MED desalination plant
    SHEN Shengqiang, ZHOU Shihe, MU Xingsen, GUO Yali
    2014, 65(9):  3366-3374.  doi:10.3969/j.issn.0438-1157.2014.09.008
    Abstract ( 316 )   PDF (740KB) ( 386 )  
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    Based on correlations of flow resistance and sea water boiling point elevation (BPE) applicable to the low-temperature multiple effect distillation (LT-MED) desalination plant, the thermodynamic losses in a large-scale LT-MED desalination plant were calculated and analyzed, including the distribution and proportion of various thermodynamic losses caused by BPE and flow resistances. The effect of the number of evaporator/condenser on thermodynamic losses was studied. The result indicates that, for a large-scale LT-MED desalination plant with constant production capacity, the total thermodynamic losses increases with the number of effects. The thermodynamic loss caused by BPE constitutes the highest proportion while that by the flow resistances can not be ignored. According to the analysis on the loss, the operating characteristics of LT-MED desalination system are summarized as small temperature difference, low pressure drop, saturation states and high sensitivity.
    Pressure drop of gas-solids distributor located at outlet of riser with combined restraint
    JIA Mengda, WANG Dewu, ZHANG Shaofeng, ZHAO Lijun, LI Rui, WU Guangheng
    2014, 65(9):  3375-3382.  doi:10.3969/j.issn.0438-1157.2014.09.009
    Abstract ( 317 )   PDF (640KB) ( 200 )  
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    Based on a cold model experimental setup of riser reactor with combined restraint outlet, an experiment was conducted to analyze pressure drop of gas-solids distributor at the outlet of riser under different circumstances. Gas-solids distributor's pressure drop increased with increasing superficial gas velocity and solids flux, with or without active operating bed. The slope of gas-solids distributor's pressure drop curve increased with increasing superficial gas velocity at lower solids flux, while decreased at higher solids flux. Pressure drop of the distributor declined with increasing distributor's aperture ratio and increasing pressure drop of the upper fluidized bed. When the pressure drop of the upper fluidized bed increased to a specific value, the holes of the distributor were all able to be passed through by gas-solids flow, with the distributor pressure drop approximately unchangeable. At the same superficial gas velocity, pressure drop of gas-solids distributor was bigger than that of conventional gas distributor.
    Effect of feeding gas on hopper discharge of pulverized coal
    LU Haifeng, GUO Xiaolei, TAO Shunlong, GONG Xin, LU Jun
    2014, 65(9):  3383-3388.  doi:10.3969/j.issn.0438-1157.2014.09.010
    Abstract ( 274 )   PDF (600KB) ( 228 )  
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    Hopper discharge is one of the most important components in the entrained-flow gasification technology of pulverized coal. Safe and stabilized hopper discharge is of great economic significance. The effect of feeding gas, including air and CO2 on hopper discharge was studied in the loop feeding system of pulverized coal. Both gravity discharge and aerated discharge were examined and analyzed. The behavior and flowability of powders would be influenced by their previous bulk or fluidized state. For gravity discharge, the pulverized coal fed by CO2 showed a higher void and thus corresponded to higher discharge rate. For aerated discharge, the pulverized coal fed by air was hard to be fluidized by CO2, resulting in lower discharge rate.
    Blockage of triangle leakage zones in heat exchanger with helical baffles
    WANG Simin, MING Yusheng, CHEN Kang, ZHANG Zaoxiao, WEN Jian, XUE Yulan
    2014, 65(9):  3389-3394.  doi:10.3969/j.issn.0438-1157.2014.09.011
    Abstract ( 455 )   PDF (2483KB) ( 380 )  
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    Four fan-shaped baffles are used to form a pitch in shell side of heat exchangers with helical baffles. There are two triangular leakage zones between the two adjacent baffles, making the shell-side fluid deviate from ideal plug flow and degrading the heat transfer performance of the heat exchanger. In this paper, the structure of fold baffle is used to block the external triangular leakage zones, so the shell-side fluid flows in approximately continuous spiral flow. The heat transfer experiments are used to evaluate the performance of the improved heat exchanger. The experimental results show that the shell-side heat transfer coefficient is increased by 11.6%-21.6% and the overall heat transfer coefficient is increased by 6.7%-19.1% with an average value of 16.9%, compared with that of conventional heat exchanger with plain baffles. The heat transfer of improved heat exchanger is intensified obviously. Although the shell-side pressure drop increases correspondingly, the increment in pumping power consumption is limited. The values of thermal performance factor are all above 1.0, with an average value of 1.071. It demonstrates that taking into account heat transfer coefficient and pressure drop, better integrative performance is obtained through the configuration optimization of baffles. It is benefit to optimizing design for heat exchangers with helical baffles.
    Flow characteristics of radial flow adsorber and its structure parameters optimization
    CHEN Yao, ZHANG Xuejun, LU Junliang, QIU Limin, ZHANG Xiaobin, SUN Daming, GAN Zhihua
    2014, 65(9):  3395-3402.  doi:10.3969/j.issn.0438-1157.2014.09.012
    Abstract ( 291 )   PDF (951KB) ( 264 )  
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    Non-uniform flow distribution along the axial direction usually exists in a Z-flow type radial flow adsorber which will decrease the utilization of adsorbents and even result in operating safety problems in cryogenic air separation. The structure parameters in a differential equation which determined the flow characteristics of Z-flow type radial flow adsorber were dimensionlessly processed, and the effects of structure parameters on flow distribution in the adsorber were investigated. The theoretical result of the flow distribution in an experimental radial flow adsorber was in agreement with the experimental data. Reducing the axial height of adsorption bed and the diameter of adsorbent particle could significantly improve flow distribution in the Z-flow type radial flow adsorber. However, the amount of processed air had little impact on flow distribution when kinematic viscosity of air and other structure parameters remained unchanged.
    Thermodynamic analysis of enhanced heat transfer process in microchannel heat sinks with complex structure
    ZHAI Yuling, XIA Guodong, LIU Xianfei, LI Yifan
    2014, 65(9):  3403-3409.  doi:10.3969/j.issn.0438-1157.2014.09.013
    Abstract ( 365 )   PDF (662KB) ( 300 )  
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    It is a typical irreversible process of flow and heat transfer in the microchannel and it is necessary to reduce the irreversibility to improve effective utilization of energy in the heat transfer process. The entropy generation rate and transport efficiency of thermal energy are derived from the first and second law of thermodynamics, which indicate that the effective utilization of thermal energy increases with the decrease of net temperature gradient of fluid in the micro heat sink. A new micro heat sink with complex structure is proposed and simulated based on the previous study. The effect of structure on entropy generation rate and transport efficiency of thermal energy is also analyzed. The results reflect that the less the net temperature gradient of fluid, the less irreversibility and the more uniform the temperature of bottom in the heat sink. Based on the definitions of thermal enhancement factor, entropy generation rate and transport efficiency of thermal energy, it is reasonable to use thermal enhancement factor to evaluate the comprehensive performance of micro heat sinks, while the other two are used to measure the irreversibility and level of utilization in the heat transfer process. In short, the evaluation criteria is provided by the first law of thermodynamics, while the essence of heat transfer enhancement is indicated by the second law of thermodynamics, giving a complete thermodynamic theory for optimizing micro heat sinks.
    Incident shock wave attenuation in oscillatory tube and influence on performance of pressure wave refrigerator
    ZHENG Minfeng, LIU Xi, HUANG Cheng, LIN Yuedong, LEI Xiaojian, LI Xuelai
    2014, 65(9):  3410-3417.  doi:10.3969/j.issn.0438-1157.2014.09.014
    Abstract ( 245 )   PDF (574KB) ( 208 )  
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    The pressure wave refrigerator represents a simple arrangement for gas cooling by its decompression and has many applications in chemical processes and energy transformation. The mechanism of the cooling effect of oscillatory tube is the conversion of the pressure energy of gas to heat through the movement of pressure waves, which are moving shock wave and unsteady expansion wave. In the present paper, the regular pattern of incident shock wave attenuation and its influence on the performance of pressure wave refrigerator are investigated by means of a single-tube set up. In the experiments, the expansion ratio is from 2.0 to 6.0, the relative length of the oscillatory tube L/d is from 87 to 737, and the exciting frequency is from 10 Hz to 240 Hz. The experimental results show that the relative strength of incident shock wave is reduced with the increase of relative position in length x/L because the energy of the reflected shock wave is exhausted by the viscosity and friction of the gas inside the tube. The other reason is the result of the gas in the tube pressurized and heated by the shock wave. The shock wave strength is also influenced by transmission and reflection effects resulted from the reflected shock wave. When the tube is relatively short, the relative strength of incident shock wave is less reduced as the tube length decreases, while the strength of the reflected shock wave at the closed end of the tube increases. The maximum refrigeration efficiency ηmax of the refrigerator increases with the tube length, but the value of ηmax is not affected obviously when the tube length increases to some value. The recommended optimal tube length L/d is 300-435 for the tube in this experiment. It helps to improve the performance of the pressure wave refrigerator under variable work condition when the amplitude of the refrigeration efficiency fluctuation is reduced as the length increases. The relative strength of the incident shock wave attenuation is concerned with the gas Reynolds number and Mach number in the front of the incident shock wave and the ratio of length to diameter. The attenuation formula is obtained by the dimensional analysis and experimental data, and the results are in good agreement with the experimental data. The maximum error is 5.70%.
    Combustion characteristics of premixed CH4/air flame in mesoscale channel with cavities
    WAN Jianlong, LIU Yi, FAN Aiwu, PI Boming, DU Yiqing
    2014, 65(9):  3418-3424.  doi:10.3969/j.issn.0438-1157.2014.09.015
    Abstract ( 300 )   PDF (11088KB) ( 260 )  
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    Premixed CH4/air combustion in a mesoscale channel with cavities were experimentally investigated and compared with that without cavity. The experimental results demonstrate that no symmetric stable flame is observed in the channel without cavities and flame is prone to inclining and pulsating. In contrast, flame can be effectively anchored by the recirculation zone and low velocity zone in the channel with cavities. When the inlet velocity is close to blowout limit, curved fluctuating flames occurs. The blowout limit of the channel with cavities is 0.8, 1.35 and 1.75 m·s-1 for the equivalence ratio of 0.8, 0.9 and 1.0 respectively, which is several times larger than the corresponding burning velocity of incoming CH4/air mixture. These indicate that the cavities have a strong ability to anchor flame. Numerical simulation is performed to help analyzing the flame blowout mechanism, and reasonable accuracy of the numerical model adopted is confirmed. Results reveal that a large shear stress exists at the transition point between the ramped cavity wall and downstream inner wall, making flame split at high inlet velocity, and it is difficult to stabilize the flame in a straight channel. Once the second part of the reaction zone is separated from the one in the cavity, it is prone to blowout. In summary, flame behavior in the mesoscale channel with cavities strongly depends on the interactions between the reaction zone and flow field.
    Numerical simulations for steam condensation in presence of air
    SU Jiqiang, WANG Hui, SUN Zhongning, ZHANG Dongyang
    2014, 65(9):  3425-3433.  doi:10.3969/j.issn.0438-1157.2014.09.016
    Abstract ( 297 )   PDF (713KB) ( 767 )  
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    The passive containment cooling system (PCCS) is widely used in the next generation of nuclear reactor systems to maintain the integrity of containment for longer time after utmost accidents such as the loss of coolant and main steam line break. For double concrete containment, the condenser is one of the most essential equipment in the PCCS and its heat transfer capability determines its performance. In the steam condensation process, the presence of large amounts of non-condensable gases will lead to serious deterioration of heat transfer, so further study on steam condensation in the presence of air must be conducted. In this study, condensation processes of steam in the presence of air are modeled by applying a user defined function added to the commercial computational fluid dynamics package. Calculated profiles of temperature, air concentration, velocity components and condensation heat transfer coefficient are compared to experimental results. The simulation results indicate a good agreement between the experimental results and model predictions. It also shows that both the latent and the sensible heat transfer coefficient decrease with the increase of air mass fraction, and the latent heat transfer is a dominant factor in the total condensation heat transfer at air mass fractions less than 50%. Local latent heat coefficient presents an upward tendency along the axial direction of heat transfer tube from the bottom to the top, while the sensible heat transfer coefficient takes an opposite trend.
    Equivalent straight pipe heat transfer model of cement clinker porous media in grate cooler
    WEN Yan, WANG Jiashun, YUE Hailong, LI Bin, LIU Bin
    2014, 65(9):  3434-3440.  doi:10.3969/j.issn.0438-1157.2014.09.017
    Abstract ( 265 )   PDF (1049KB) ( 231 )  
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    For the study on porous cement clinker, researchers solve the equations of Darcy's law and local no-thermal equilibrium heat transfer based on the theory of heat transfer of fluid flow in porous media. However, the solving process is complex and not convenient for engineering application. A kind of straight pipe equivalent heat transfer model was established by introducing the theory of straight pipe heat exchange to unit body of porous cement clinker. In order to decrease the difficulty of the solving process, the methods and ideas based on the theory of straight pipe heat transfer were used to solve the heat transfer process of porous cement clinker. On the premise of ensuring calculation precision, the changes of temperatures of both clinker and gas with time were obtained. A self-designed experimental equipment was used to verify the temperature expressions at different porosities. The calculation results basically agreed with the experimental data, which verified the feasibility of straight pipe equivalent heat transfer model.
    An experimental investigation on a novel liquid thermoelectric cooling device
    ZHANG Bo, WANG Yaxiong
    2014, 65(9):  3441-3446.  doi:10.3969/j.issn.0438-1157.2014.09.018
    Abstract ( 435 )   PDF (2363KB) ( 1259 )  
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    A novel liquid thermoelectric cooling device is developed and assembled for sub-ambient temperature cooling of chips in over-clocking or super calculating. A testing system was set up and experiments were conducted to investigate the thermal performance of the novel cooling device under various application conditions. Results showed that the maximum heat dissipating capacity was 45.2 W·cm-2 and the lowest total thermal resistance was 0.107℃·W-1 at case temperature of 65℃ and cooling air flowrate of 7-13 m·s-1. The case temperature of the heat source was reduced 4.0 and 4.6℃, respectively, at cooling air flowrate of 9 and 13 m·s-1, with input heat flux of 28.5 W·cm-2 and TEC at its optimum input voltage. The cooling performance of the device is also closely related with the input voltage of TEC. With the heat flux of heat source at 28.5 W·cm-2 and cooling air flowrate of 9 and 13 m·s-1, the optimum operating voltage of TEC is 28 and 32 V, respectively.
    Steam gasification characteristics of coal char in micro-fluidized bed reaction analyzer
    JI Ying, ZENG Xi, YU Jian, YUE Junrong, LI Aoming, XU Guangwen
    2014, 65(9):  3447-3456.  doi:10.3969/j.issn.0438-1157.2014.09.019
    Abstract ( 365 )   PDF (4444KB) ( 415 )  
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    Two types of char were made through rapid quenching in liquid nitrogen (Char-Q) and natural cooling in argon (Char-S). Systematic comparison was performed for the chars in terms of structure and gasification characteristics measured in the micro-fluidized bed reaction analyzer (MFBRA), a well-proven isothermal reaction analyzer developed by Institute of Process Engineering, Chinese Academy of Sciences. Char-Q had the higher surface area but smaller average size of pores, while Char-S from slow cooling showed higher degree of graphitization. Gasification tests in MFBRA demonstrated that Char-Q had obviously higher reaction rate, and activation energy determined according to the iso-conversion method was higher for Char-S. Particularly, MFBRA enabled the determination of activation energy not only for the overall C conversion but also for the formation reactions (a reaction system) of every individual gas component, thus allowing a rather comprehensive analysis of the reaction nature. Consequently, in order to get the gasification characteristics close to the hot char intrinsic nature, Char-Q should be used, while MFBRA provided as well a more effective instrument for measurement of the differential reaction characteristics involving steam agent.
    Preparation of CuCrO2-WO3 and its photocatalytic performance for hydrogen production
    WANG Guiyun, LIU Xianping, ZHAO Qian, WANG Yanji, LIN Ruirong
    2014, 65(9):  3457-3463.  doi:10.3969/j.issn.0438-1157.2014.09.020
    Abstract ( 495 )   PDF (3952KB) ( 827 )  
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    The principle of p-n type semiconductor composite photocatalysts is discussed as a strategy to develop efficient photocatalysts for water splitting. Composite of p-type and n-type semiconductor has an advantage in taking full use of each semiconductor's function of oxidation and reduction, which could facilitate the photo-induced electron/hole pairs' separation by the inner electric field, enhancing the photocatalytic efficiency of the system. CuCrO2 was synthesized by a novel combustion reaction method with glycerin as fuel, and WO3 was prepared by the tungsten acid decomposition method. The configurations CuCrO2-WO3 and Ru/(CuCrO2-WO3) were successfully prepared by mechanical grinding and heat-treatment. The prepared samples were characterized by using X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance (UV-vis DR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of CuCrO2, WO3, CuCrO2-WO3 and Ru/(CuCrO2-WO3) were evaluated under xenon lamp irradiation. The factors including pH of grinding media and Ru loading were also investigated. When glycerin was used as the sacrificial reagent under xenon lamp irradiation, CuCrO2 or WO3 powders alone was not able to catalyze H2 generation from water splitting, while coupled photocatalysts of CuCrO2-WO3 displayed remarkable photocatalytic activity. The improvement of photocatalytic activity was attributed to the formation of p-n junctures at the interface of CuCrO2-WO3. When grinding media was at pH 8, dispersion of WO3 was particularly better, which contributed to more efficient compounding of the two powders and better activity of the composite as a consequence. Ru loading as cocatalyst also remarkably enhanced photocatalytic hydrogen production. The 0.5% (mass) Ru/(CuCrO2-WO3) exhibited better photocatalytic activity for splitting pure water into hydrogen under 300W xenon lamp irradiation, on which H2 production was about 10 μmol for 3 h.
    Air strengthening of hydrometallurgy process for leaching vanadium from converter slag
    LIU Zuohua, Ayinuer·Nueraihemaiti, LIAN Xin, DU Jun, FAN Xing, TAO Changyuan
    2014, 65(9):  3464-3469.  doi:10.3969/j.issn.0438-1157.2014.09.021
    Abstract ( 374 )   PDF (3989KB) ( 350 )  
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    Low valency vanadium produced in the insufficient sodium roasting process affects the improvement of vanadium leaching rate. Anthraquinone-2,6-disulfonic acid disodium salt (ADA) or tannin as oxygen carrier was added into the water leaching process to transfer oxygen and to strengthen the air oxidation process of low valency vanadium. Phases of reaction system were analyzed using XRD, SEM, UV and UV-Vis DRS. The reaction mechanism of the process was also studied to prove its theoretical feasibility. Low valency vanadium was effectively oxidized by ADA or tannin, and vanadium leaching ratios increased from initial 89.47% to 92.84% and 93.64%, while vanadium contents in the leaching residue reduced from 1.1% to 0.52% and 0.47%, respectively. It also proved that catalysts had no negative effect on the consequential process.
    Thermal decomposition kinetics of humic acid
    CHENG Liang, ZHANG Baolin, XU Li, HOU Cuihong, LIU Guoji
    2014, 65(9):  3470-3478.  doi:10.3969/j.issn.0438-1157.2014.09.022
    Abstract ( 969 )   PDF (784KB) ( 546 )  
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    Process and kinetics of thermal decomposition of humic acid were studied with TG-DTG techniques. Thermal decomposition temperature of humic acid was in the range of 284.65-417.16℃. The structure of humic acid was characterized with FT-IR, 1H NMR and 13C NMR. The kinetic parameters, including activation energy and pre-exponential factor of the thermal decomposition process of humic acid were calculated with the Flynn-Wall-Ozawa (FWO), Kissinger and Šatava-Šesták method respectively. Activation energy and logarithmic value of pre-exponential factor were found to be 210.83 kJ·mol-1 and 17.55, respectively. Moreover, reaction order and mechanism of thermal decomposition and thermodynamic parameters were also studied. Thermal decomposition of humic acid was a second-order reaction, and the mechanism of the decomposition process was obtained. The maximal used temperature of humic acid maintaining one-minute lifetime in N2 atmosphere was 278℃. Meanwhile, the thermodynamic paramaters of ΔH, ΔS and ΔG were calculated as 67.99 kJ·mol-1, -164.83 J·(mol·K)-1 and 176.36 kJ·mol-1, respectively.
    Pyrolysis kinetics modeling of flame retarded HIPS
    MA Chuan, SUN Lushi, JIN Limei, XIANG Jun, HU Song, SU Sheng
    2014, 65(9):  3479-3484.  doi:10.3969/j.issn.0438-1157.2014.09.023
    Abstract ( 307 )   PDF (520KB) ( 187 )  
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    A thermo-gravimetric (TG) study of flame retarded high impact polystyrene((Br-Sb-HIPS) pyrolysis was conducted at various heating rates(5℃·min-1,10℃·min-1, 15℃·min-1). A kinetic model of the pyrolysis of flame retarded HIPS that contains three series reaction was built. The activation energy of pyrolysis reaction of flame retarded HIPS obtained by the method of Flynn-Wall-Ozawa changed between 103-307 kJ·mol-1. Parameters were solved by a multidimensional unconstrained nonlinear minimization method. The values of activation energy were 191.632, 213.263 and 238.331 kJ·mol-1 and the values of pre-exponential factor were 11.641, 12.772, 11.666 min-1 respectively for the three reactions. The kinetic model was able to accurately predict the pyrolysis process of flame retarded HIPS.
    Ethylene oligomerization catalyzed by PNP/Cr(Ⅲ)/MAO in biphase systems
    WANG Mei, SHI Pengfei, CHEN Yanhui, JIANG Tao
    2014, 65(9):  3485-3489.  doi:10.3969/j.issn.0438-1157.2014.09.024
    Abstract ( 576 )   PDF (482KB) ( 409 )  
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    1-n-Butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6])/cyclohexane biphasic system was used for studying performance of ethylene oligomerization catalyzed by diphosphinoamine ligand (PNP)/Cr(Ⅲ)/ methylaluminoxane(MAO). The effect of reaction temperature, molar ratio of Al/Cr and ionic liquid concentration on catalytic activity and product distribution was investigated. The results showed that compared with homogeneous catalysis system, the action of catalytic active center in biphase systems changed from ethylene tetramerization to ethylene trimerization. selectivity was up to 97.40%. The product existed in the organic solvent while the catalyst was dissolved in ionic liquids, which made the separation of product and recycle of catalyst easy.
    Binary adsorption equilibrium of CH4, N2 and CO2 on zeolite ZSM-5
    SHEN Wenlong, LI Jiaxu, YANG Ying, LI Ping, YU Jianguo
    2014, 65(9):  3490-3498.  doi:10.3969/j.issn.0438-1157.2014.09.025
    Abstract ( 282 )   PDF (708KB) ( 399 )  
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    Adsorption equilibrium isotherms of CH4, N2 and CO2 on zeolite ZSM-5 were measured by Rubotherm magnetic suspension balance in the pressure range of 0-500 kPa and the temperature range of 273-353 K. Sips model, Toth model and MSL model were used to fit the experimental data with acceptable accuracy, and the model parameters were obtained by the non-linear regression method. Binary adsorption isotherms of CO2/N2, CO2/CH4 and CH4/N2 were measured by the magnetic suspension balance with different compositions in the pressure range of 0-500 kPa at 293 K. The Sips model-based ideal adsorbed solution theory and two-component MSL model were used to simulate the competitive adsorption equilibrium isotherms of CO2/N2, CO2/CH4 and CH4/N2. Furthermore, the selectivity of CO2/N2, CO2/CH4 and CH4/N2 gas mixtures were calculated, and the feasibility of adsorption separation, using zeolite ZSM-5 as adsorbent to separate CO2 from flue gases (CO2/N2), CH4 from landfill gases (CO2/CH4) and coal mine gases (CH4/N2) was evaluated.
    Application of polyvinylidene fluoride/polydimethylsiloxane composite membrane in butanol recovery
    DU Guangqing, CHEN Lijie, XUE Chuang, BAI Fengwu
    2014, 65(9):  3499-3504.  doi:10.3969/j.issn.0438-1157.2014.09.026
    Abstract ( 366 )   PDF (4379KB) ( 313 )  
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    A polyvinylidene fluoride (PVDF)/polydimethylsiloxane (PDMS) composite membrane for butanol recovery was fabricated by coating a dense PDMS separation layer on a PVDF porous support layer prepared by phase inversion. The total flux and separation factor of the PVDF/PDMS composite membrane could be 158.2 g·m-2·h-1 and 17.3, respectively, when feed solution was 15 g·L-1 butanol at 37℃ with a flow rate 1.6 L·min-1. To simulate the fermentation liquor, acetone and ethanol were added into the feed solution in a ratio 6(butanol):3:1, the total flux of PVDF/PDMS composite membrane increased to 189.5 g·m-2·h-1, but separation factor decreased to 14.8. Furthermore, fermentation broths with/without biomass as feed solution were investigated to evaluate pervaporation performance of the PVDF/PDMS composite membrane. The total flux and separation factor were 120.2 g·m-2·h-1 and 19.7 for without biomass case, 122.1 g·m-2·h-1 and 16.7 for with biomass case, respectively. Compared with PDMS membrane, the performance of PVDF/PDMS composite membrane had significant improvement for butanol recovery, indicating that it is of potential for industrial application of butanol recovery.
    Effect of water and impurity accumulation in reclaimed solvent on crystallization of carbazole from crude anthracene
    YE Cuiping, WU Tingting, LI Wenying, ZHENG Huan, FENG Jie
    2014, 65(9):  3505-3511.  doi:10.3969/j.issn.0438-1157.2014.09.027
    Abstract ( 254 )   PDF (2918KB) ( 307 )  
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    To investigate the effect of water and other impurities in solvents on crystallization of carbazole from crude anthracene, the accumulation amount of impurities in xylene and water in ethanol in the solvent recycling were studied. Results showed that with the increase of xylene recycling, the main impurities in mother solution gradually accumulated in xylene, with the concentration of naphthalene up to 0.35 mg·ml-1 after recycling twice, and the carbazole content in the corresponding filter cake was reduced about 2.77% (mass) and the yield decreased 7.05% (mass). At the same time, the accumulation of impurities makes solvent recovery difficult, and the loss ratio of xylene increased from 44.75% (vol) to 79.17% (vol) after recycling three times. Water was gradually accumulated to 6.65% (vol) in ethanol. The purity of carbazole was higher than 98% (mass) when the water content added was between 0 to 12% (vol). The relative crystallinity of carbazole decreased from 45.67% to 40.79% when added water content is between 0 and 6% (vol) in ethanol; with the added water content of 9% (vol) and 12% (vol) in ethanol, it increased to 48.85% and 48.52%, respectively.
    Boiler system design based on stochastic programming under uncertain steam demand and equipment failure
    LIU Chang, SUN Li, HE Gaohong, GAI Limei
    2014, 65(9):  3512-3518.  doi:10.3969/j.issn.0438-1157.2014.09.028
    Abstract ( 287 )   PDF (415KB) ( 171 )  
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    The utility system design would consider the reliability to respond to boiler failure even shut down. The design would ensure system flexibility for the fluctuation of process steam demand as well. In this work, boiler system design was studied considering both the uncertainty of process steam demand and equipment failure based on mathematical programming. Probability distribution was used for fluctuation of process steam demand and the Markov model was used to deal with boiler failure to express uncertain parameter with probability. The approach of two-stage stochastic programming was to compensate the constraint violations caused by uncertain steam demand and boiler failure to reduce the effect on optimization and constraints. A mixed integer linear programming model (MILP) was formulated with the objective of minimum annual cost to design system configuration, equipment modes and operation of compensating flexible steam demand and equipment failure.
    Multiple steady states of fluid catalytic cracking unit with high-efficiency regenerator: effect of reaction temperature control strategy on heat feedback
    WANG Rui, LUO Xionglin, XU Feng
    2014, 65(9):  3519-3526.  doi:10.3969/j.issn.0438-1157.2014.09.029
    Abstract ( 286 )   PDF (957KB) ( 193 )  
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    Analyses of multiple steady states of a fluid catalytic cracking unit (FCCU) with high-efficiency regenerator with the riser reaction temperature under open loop and closed loop control were performed based on the theory of output multiplicity and input multiplicity. The multiple steady states under these two conditions were determined with respect to the amount of the added CO combustion promoter. The heat removal curve was found monotonously increasing with riser reaction temperature under open loop control, which resulted in the existence of three multiple steady states because of weak coupling between regenerator temperature and riser reaction temperature. On the other hand, the heat feedback of regenerator and riser reactor changed under closed loop control because regenerated catalyst flow rate could be used as an extra measure to compensate the difference between regenerator temperature and riser reaction temperature to enhance coupling between regerator temperature and riser reactor temperature. Multiple steady states would exist only when CO promoter was extremely insufficient. Otherwise, only one steady state existed under current operating condition which avoided multiple steady states with riser reaction temperature under open loop control.
    Modeling of batch process based on higher order partial least squares
    WANG Jianping, HU Yi, SHI Hongbo
    2014, 65(9):  3527-3534.  doi:10.3969/j.issn.0438-1157.2014.09.030
    Abstract ( 365 )   PDF (781KB) ( 411 )  
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    The products of batch processes are closely related to the daily life of modern people, and it is crucial for batch process monitoring to establish a model based on the normal process data sets. In this paper, according to the characteristics of batch process, a new generalized multilinear regression model, termed the higher order partial least squares (HOPLS), is introduced with the aim to better model the three-way batch data. It differs substantially from the traditional modeling approach, and instead of unfolding the three-way array to a two-way array, it explains the data by a sum of orthogonal Tucker tensors. Higher order orthogonal iteration (HOSVD), tensor transformation and higher order orthogonal iteration (HOOI) are used to find the latent vectors, which contain the maximum information of independent variables and dependent variables simultaneously. And the loading vectors are calculated at the same time. For the new observation values, the dependent variables will be predicted through the output of the model. Finally, the feasibility and efficiency of the method are verified through the PenSim2.0 simulation platform.
    A real-time optimization approach for uncertain batch processes
    YE Lingjian, MA Xiushui, SONG Zhihuan
    2014, 65(9):  3535-3543.  doi:10.3969/j.issn.0438-1157.2014.09.031
    Abstract ( 296 )   PDF (626KB) ( 291 )  
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    An integrated batch-to-batch and within batch optimization approach was proposed for real-time optimization of uncertain batch processes. Firstly, the structural information of optimal input trajectory was obtained by optimizing the nominal model, then the whole trajectory was parametrized as scalar variables and sub-trajectories. For the active terminal constraints in the necessary conditions of optimality, the batch-to-batch optimizing approach was taken to satisfy constraint condition. For the sensitivity part, which contained unknown disturbances that entered the optimal feedback, a regression approach was proposed to approximate the optimal input using measurements, hence within batch optimization could be realized. The effectiveness of the proposed integrated optimization approach was verified through the study of a batch reactor.
    Building predicting model of paper tensile strength based on partial least-squares approach
    LI Yuanhua, TAO Jingsong, LI Jigeng, LIU Huanbin
    2014, 65(9):  3544-3551.  doi:10.3969/j.issn.0438-1157.2014.09.032
    Abstract ( 304 )   PDF (644KB) ( 314 )  
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    The problems existing in the mechanism models include difficulty in obtaining the parameters, and most of the parameters had little relationship with production which reduced its practicability. The partial least-squares method (PLS) was used to establish the model to predict paper strength based on a production line of a corrugated paper mill. By selecting parameters and their data aided with mechanism analysis, we built the model and obtained the key parameters. The results showed that the model had a good precision that its Pearson's value was 0.732, root mean square error (RMSE) was 276 N·m-1, and mean relative error (MRE) was 5.17%. Besides, the model had a good analytical ability that the key elements could be interpreted very well from the mechanism angle.
    Chemical production planning and scheduling integration under demand uncertainty
    TIAN Ye, DONG Hongguang, ZOU Xiong, LI Shuangshuang, WANG Bing
    2014, 65(9):  3552-3558.  doi:10.3969/j.issn.0438-1157.2014.09.033
    Abstract ( 533 )   PDF (727KB) ( 357 )  
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    Production planning and scheduling are two of the most important decision-making problems in supply chain optimization. To ensure the efficiency of decision-making, planning and scheduling were integrated, with consideration of demand uncertainty. For a multi-period production planning and scheduling problem, planning and scheduling deterministic models were established in each period firstly, and they were integrated through production correlation. Then, demand uncertainty was introduced and decision variables were represented with a finite number of scenarios in a two-stage stochastic programming model. At last, rolling horizon strategy was used to achieve consistency between planning and scheduling results in an iterative process. The case study demonstrated that compared with the conventional method, the stochastic programming method could reduce total cost under demand uncertainty. Combined with the hierarchical integration method, production operational and economic optimization was achieved.
    Novel surface pretreatment process of aluminum alloy with fluoride-free and ammonium-free formula
    ZHANG Chao, LIU Qingfen, HUANG Xiaozhu, LIANG Xiangfeng, LI Wangliang, WANG Xiao, LIU Yinting, LIU Huizhou
    2014, 65(9):  3559-3567.  doi:10.3969/j.issn.0438-1157.2014.09.034
    Abstract ( 280 )   PDF (2689KB) ( 316 )  
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    A novel aluminum alloy surface pretreatment process with fluoride-free and ammonium-free formula was developed. Through the two-step process of pretreatment etching-neutralizing, the aluminum alloy surface was smooth and had excellent sand finishing, the aluminum consumption was less than 2.0%. The sand finishing performance of the new process was better than that in the traditional alkaline-etching process, and was close to the traditional acid-etching process. The aluminum consumption of the new process was reduced by 71% compared with the traditional alkaline-etching process, and was close to the traditional acid-etching process. The process duration was 23% and 31% faster than the traditional alkaline-etching process and traditional acid-etching process, respectively. The optimum composition of the formula was: Na2CO3 (80 g·L-1), NaOH (8 g·L-1), Na2SO4 (25 g·L-1), Na3PO4 (20 g·L-1), SDS (0.6 g·L-1) and glycerol (5 g·L-1). The process was operated at 55℃ for 10 min. This process achieved following functions in one-step: degreasing, sand-finishing, surface mechanical lines-eliminating. This novel process has the advantages of lower pollution and water consumption, shorter process and higher efficiency, which is environment friendly and energy efficient.
    Average temperature coupling calculation method for end faces of contact mechanical seals
    WEI Long, GU Boqin, LIU Qihe, ZHANG Penggao, FANG Guifang
    2014, 65(9):  3568-3575.  doi:10.3969/j.issn.0438-1157.2014.09.035
    Abstract ( 362 )   PDF (704KB) ( 222 )  
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    Mutual coupling calculating method of average temperature and friction factor of end face for contact mechanical seal was studied. Simplifying the mechanical seal ring as equal cross-section equivalent cylinder, average temperature calculation equation of end face for contact mechanical seal was derived, and the method of simplifying the mechanical seal ring as equal cross-section equivalent cylinder was given. Friction factor calculation model of end face for mechanical seal was established based on fractal theory. Taking into account the mutual coupling relationship between average temperature and friction factor of end face, the calculation method of average temperature was proposed. Influence factors of average temperature for B104a-70 mechanical seal were analyzed by simulation. Average temperature of end face increased linearly with increasing spring pressure and sealant pressure, and increased approximately linearly with increasing rotating speed, and the smoother the end face, the better the linear relationship and the greater the increase. Average temperature of end face increased nonlinearly with increasing fractal dimension or decreasing characteristic length scale. The change of average temperature was small when end face was coarse. It increased rapidly with increasing fractal dimension or decreasing characteristic length scale when end face was smooth.
    Enhanced production of spinosad with strains of Saccharopolyspora spinosa by genome shuffling
    XIA Yanchun, WANG Chao, CHEN Yuan, WU Jianglei, ZOU Qiulong, ZHANG Xiaolin, LI Chun
    2014, 65(9):  3576-3582.  doi:10.3969/j.issn.0438-1157.2014.09.036
    Abstract ( 271 )   PDF (692KB) ( 214 )  
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    In this study, genome shuffling of eight original strains obtained by various methods of chemical and physical mutations was used to achieve rapid improvement of spinosad production. The conditions of preparation, regeneration, parents inactivation and fusion of protoplast of the original strain were investigated. The strain grown for 65 h was treated by 4 mg·ml-1 lysozyme at 39℃ for 20 min, and preparation rate and regeneration rate were 92.30% and 7.66%, respectively. The protoplasts were inactivated by heating at 60℃ for more than 90 min and UV treatment more than 200 s, respectively. The inactivated protoplasts were fused and regenerated in polyethylene glycol (PEG 6000, 50%) for 15 min, and fusion rate was about 1.18%. After three rounds of genome shuffling, a high yielding strain, designated as S.spinosa 3-652, was isolated. The increased yield was about 36.07% higher than that of the original strain. Subculture experiments indicated that the high producers were stable.
    Biosynthesis of genipin from gardenoside catalyzed by β-glucosidase in two-phase medium
    WAN Lihua, YAO Zhong, NI Fang, WEI Min, ZHOU Zhi, WANG Haoqi, SUN Yun, ZHONG Zhaoxiang
    2014, 65(9):  3583-3591.  doi:10.3969/j.issn.0438-1157.2014.09.037
    Abstract ( 807 )   PDF (637KB) ( 411 )  
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    Genipin is an important bio-crosslinking agent with multiple physiological activities. In this paper, the competitive inhibition for activity of β-glucosidase by genipin was demonstrated. The stabilities of β-glucosidase in different organic solvents were investigated. Stability of β-glucosidase was satisfactory in the octanol-water and hexanol-water medium. The partition coefficients for gardenoside in the octanol-water and hexanol-water system were 0.17 and 0.76, while those for genipin were 42.57 and 37.75 respectively. The process for preparation of genipin was carried out in water, octanol-water and hexanol-water respectively, while gardenoside concentration was 0.25 μmol·ml-1. The obtained genipin yields were 89.17%, 93.96% and 90.16% respectively. Furthermore, the effect of gardenoside concentration on genipin yield was also investigated. While in the octanol-water system, conversion rate of genipin was as high as 91.9% at the gardenoside concentration of 2.0 μmol·ml-1, an increase of 12.2% compared to that in water. Using the octanol-water medium was helpful for partially eliminating product inhibition, improving genipin yield and simplifying product recovery.
    Numerical simulation of coal pyrolysis using FD model
    YU Junwu, CHEN Yongli, HE Rong, ZHANG Yanguo
    2014, 65(9):  3592-3598.  doi:10.3969/j.issn.0438-1157.2014.09.038
    Abstract ( 376 )   PDF (588KB) ( 279 )  
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    For numerical simulation of coal pyrolysis using the fragmentation and diffusionn (FD) model, a numerical method was proposed. The pyrolysis of three kinds of coal in a heated-tube reactor was simulated respectively, and the results were compared with the experimental results and also with the numerical results of FG-DVC model and CPD model. The effect of pyrolysis temperature and particle diameter on coal pyrolysis product was also studied. The accuracy of FD model was higher than FG-DVC model and CPD model, proving that FD model was more applicable for numerical simulation of coal pyrolysis. The gas product increased rapidly by increasing pyrolysis temperature until 1373 K, and then was nearly constant when pyrolysis temperature was higher than 1373 K. The tar product decreased with increasing pyrolysis temperature, and less time was needed to reach the maximum tar amount. The gas product and tar product both decreased by increasing particle diameter of coal, while more time was needed to reach the maximum tar amount.
    Degradation of dichloromethane by absorption combined with iron-active carbon micro-electrolysis
    HUANG Guifeng, HUANG Liwei
    2014, 65(9):  3599-3603.  doi:10.3969/j.issn.0438-1157.2014.09.039
    Abstract ( 596 )   PDF (480KB) ( 358 )  
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    The removal of dichloromethane by absorption combined with iron-active carbon micro-electrolysis in a tube reactor filled respectively with iron mash, activate carbon particle and combined iron-active carbon (Fe-C), was investigated. The result shows that removal of DCM is higher for Fe-C mixed packing than for iron mash or activate carbon one. Oxidation Reduction Potential(ORP) of solution in the reactor filled with Fe-C mixed packing rapidly drops, which can create a more reducing environment at around 180 mV, while for other two fillers there is significant difference. It was also found that removal and dechlorination of DCM can be enhanced when pH of aqueous solution decreases. After 300 min the Cl- concentration in solution is about 4 times higher at pH 1.5 than at pH 5, and the maximum rate of Cl- generation is 2.85%. The gaseous product from dechlorination of dichloromethane by Fe-C is mainly methane.
    Migration and distribution characteristics of trace elements in 220 MW cogeneration boiler
    WANG Chao, LIU Xiaowei, WU Jianqun, ZHOU Zijian, CHEN Jun, XU Minghou
    2014, 65(9):  3604-3608.  doi:10.3969/j.issn.0438-1157.2014.09.040
    Abstract ( 307 )   PDF (466KB) ( 190 )  
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    The experiment was conducted in a 220 MW cogeneration boiler in Beijing. The Dekati Gravimetric Impacter system was used to sample particulate matter (PM) at the inlets of selective catalytic reduction (SCR), electrostatic precipitation (ESP) and flue gas desulfurization (FGD) in this boiler, to investigate the migration characteristics of trace elements in the flue gas tunnel. In addition, distribution of trace elements in solid combustion residues was also studied. The concentrations of As, Cd, Cr and Pb in PM at the inlet of ESP were obviously higher than those at the inlet of SCR. The masses of gaseous As, Cd, Cr and Pb converted to solid in the process of flue gas flow from SCR to ESP accounted for 26%, 16%, 12%, 11% of the total masses in coal respectively. In the process of flue gas flow from ESP to FGD, the concentrations of As and Cd in PM slightly increased, while those of Cr and Pb were almost constant. The concentrations of Mn at the three sampling sites were almost the same. Most trace elements remained in the fly ash collected by ESP, and at the outlet of ESP, the masses of As, Cd, Cr and Pb in the four size segments with size <10 μm increased with decreasing particle size, however, mass distribution of Mn was similar with that of PM.
    Improving removal of PM2.5 by electrostatic precipitator with chemical agglomeration
    LIU Yong, ZHAO Wen, LIU Rui, YANG Linjun
    2014, 65(9):  3609-3616.  doi:10.3969/j.issn.0438-1157.2014.09.041
    Abstract ( 548 )   PDF (2264KB) ( 478 )  
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    Emission of fine particles from coal combustion is an important source of atmospheric PM2.5. The removal of PM2.5 from coal combustion by electrostatic precipitator (ESP) with adding agglomerant solution and evaporating treatment of desulfurized wastewater was investigated experimentally based on the coal-fired thermal system. Change of concentration and diameter distribution of particles were tested before and after agglomeration, and the influence factors, including concentration of agglomerant solutions, temperature of flue gas at the point of addition,agglomeration solution pH,flue gas flow, and diameter of spray droplets were analyzed. The average diameter of particles could grow more than four times with the effect of wetting, liquid bridge force and adsorption bridging, and the PM2.5 concentration at ESP outlet could decrease by more than 40% under typical flue gas conditions. Increasing concentration of agglomeration solution could promote PM2.5 removal. Reducing agglomeration solution pH was better for agglomeration by making the polymer chain more soft stretch. The PM2.5 concentration at ESP outlet had no change after spraying desulfurized wastewater, and the PM2.5 concentration decreased when adding agglomeration solution.
    Effect of TiO2 dopant on CO2 capture performance of Na2CO3/Al2O3
    DONG Wei, CHEN Xiaoping, WU Ye
    2014, 65(9):  3617-3625.  doi:10.3969/j.issn.0438-1157.2014.09.042
    Abstract ( 238 )   PDF (7834KB) ( 204 )  
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    The control of CO2 emission by using sodium-based solid sorbents is receiving attention increasingly because of low reaction temperature and low energy consumption. However, there is a primary drawback for it, i.e. low reactivity with CO2 during sorption process. So, a modified sodium-based solid sorbent, Na2CO3/NaHCO3 supported on alumina and modified by TiO2, was proposed for CO2 capture and characterized by SEM, XRD and TG. The results indicate that TiO2 is stable in whole range of operation temperature of capturing CO2 process and after use there is no formation of Ti compounds except TiO2. More importantly, after dopping TiO2 the CO2 capacity of the sorbent increases and its reaction rate with CO2 goes also up. The reaction products are NaHCO3 and Na5H3(CO3)4. However if too much TiO2 was doped, block of sorbent microstructure could take place, leading to unfavourable effect on the CO2 capture process.
    Characterization of structure and pyrolysis behavior of lignin
    CHEN Lei, CHEN Hanping, LU Qiang, SONG Yang, DING Xuejie, WANG Xianhua, YANG Haiping
    2014, 65(9):  3626-3633.  doi:10.3969/j.issn.0438-1157.2014.09.043
    Abstract ( 416 )   PDF (673KB) ( 1049 )  
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    The influence of extraction method and structure type on the pyrolysis behavior of lignin was investigated. The functional groups and pyrolysis characteristics of Klason lignin extracted from cotton stalk and walnut shell by the Klason method (labeled as KCSL and KWSL, respectively), and milled wood lignin extracted from walnut shell via the Björkman method (labeled as BWSL), were analyzed with Fourier transform infrared spectroscopy (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). The results were compared with commercial alkali lignin (CAL). The FTIR results revealed that alkali lignin, cotton stalk lignin and walnut shell lignins were Type G, Type GS and Type HGS, respectively. The pyrolysis results from Py-GC/MS suggested that the products distribution of various lignins were affeted by material type and extraction method greatly. The contents of catechol derivatives obtained from KCSL, KWSL and BWSL were 28.18%, 18.12% and 35.11%. Meanswhile modification of BWSL was mainly attributed to the breakage of benzyl aryl ether linkages, whereas cleavage of ether bonds at the α-and β-positions on the propanoid side chain was the marked feature of Klason lignin.
    Waste heat recovery of blast furnace slag and utilization for production of hydrogen from biomass transformation
    TONG Li, HU Songtao, LUO Siyi
    2014, 65(9):  3634-3639.  doi:10.3969/j.issn.0438-1157.2014.09.044
    Abstract ( 316 )   PDF (1471KB) ( 189 )  
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    Blast furnace (BF) slag, one of main byproducts in steelmaking industry, is of high sensible heat and contains some metal oxides, which both can be utilized and is very beneficial to catalytic converse of tar and low carbon hydrocarbons for production of hydrogen-rich gas. Based on this idea, to realize heat recovery of BF slag and utilization for biomass catalytic gasification to generate hydrogen-rich gas, a heat recovery and catalytic conversion system was proposed in this paper. The liquid-solid transition state particles are firstly made by centrifugal granulation from liquid BF slag and then taken them as heat carrier for biomass gasification in a moving-bed reactor, and due to catalysis of multi-metal oxide the selectivity of production hydrogen is improved. Ultimately, the low-grade waste heat of liquid BF slag is translated into the high grade hydrogen energy. To examine main factors influencing gas composition and product distribution, gasification experiments are conducted. The results show that BF slag shows a good catalytic activity for tar cracking and methane reforming. With increase of BF temperature and decreases of particle size the tar content in gasification product decreases and the quality of hydrogen-rich gas improves. At the optimum conditions: BF slag particle size below 2 mm as heat carrier and catalyst, the gas yield can reached 1.65 m3·kg-1, hydrogen content 53.22% and tar content only 2.52%.
    Effects of nitrite on integrated process of denitrification with anaerobic acidogenesis
    YIN Zhixuan, XIE Li, WANG Rui, ZHOU Qi
    2014, 65(9):  3640-3646.  doi:10.3969/j.issn.0438-1157.2014.09.045
    Abstract ( 335 )   PDF (515KB) ( 238 )  
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    The effects of nitrite on integrated process of denitrification with anaerobic acidification were conducted in a batch reactor using cassava stillage (CS) as substrate. The results showed that the final volatile fatty acids(VFA) production of anaerobic reactor was similar for with and without adding nitrate (600 mg·L-1 ), but severe inhibiton of acidogenesis took place after adding the same amount of nitrite and the final VFA production was only 1.8% of that of the blank reactor. The decrease of anaerobic acid production in the nitrate reduction process was mainly due to the presence of nitrite. A small amount of nitrite could strongly suppress anaerobic acidogenesis, and the effects of nitrite on VFA composition was n-butyric>propionic>acetic acid. With decrease of ratio, nitrite reduction rate decreased from 74.9% to 22.2%, and was suppressed almost completely (>90%) at the concentration free nitrous acid (FNA) above 0.05 mg·L-1. Furthermore, with increase of ratio the proportion of denitrification decrease gradually in nitrite reduction, while dissimilatory nitrate reduction to ammonium (DNRA) process became dominant gradually.
    Characteristics of anaerobic granular sludge in EGSB reactor treating traditional Chinese medicine wastewater
    SU Chengyuan, LIU Xingzhe, WANG Kaiyao, LI Weiguang
    2014, 65(9):  3647-3653.  doi:10.3969/j.issn.0438-1157.2014.09.046
    Abstract ( 384 )   PDF (807KB) ( 396 )  
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    The characteristics of granular sludge in the EGSB reactor treating TCM wastewater were analyzed in terms of particle size distribution (PSD), integrity coefficient (IC), metal content and extracellular polymeric substances (EPS) of granular sludge. When COD concentration was 2000-5000 mg·L-1, hydraulic residence time (HRT) was 12 h, temperature was 30℃, the peak of PSD was in the range of 500-1000 μm, IC value was less than 20, and the contents of total EPS, protein, polysaccharide in granular sludge were 85.59, 63.67 and 21.92 mg·(g VSS)-1, respectively. At this stage, flocculation of granular sludge was good, and its mechanical strength was high. When HRT was reduced to 6 h, IC value increased to 30.03, and the ratio of protein and polysaccharide increased to 6.86. However,the concentration of polysaccharide in granular sludge decreased to 18.11 mg·(g VSS)-1. When temperature decreased to 20℃, the peak of PSD was in the range of 250-750 μm and IC value was 32.11. The concentrations of Ca2+, Mg2+ and Mn2+ were only 20.78, 4.79 and 0.94 mg·L-1, respectively. At the same time, the contents of total EPS, protein, polysaccharide in granular sludge were 69.04, 58.87 and 10.17 mg·(g VSS)-1, respectively. During this period, granular sludge was washed out from the EGSB reactor and COD removal efficiency decreased.
    Performance evaluation and energy efficiency analysis for magnetic refrigeration near room temperature
    LIU Chaopeng, WU Jianghong, HUANG Yihe, TANG Yongbai
    2014, 65(9):  3654-3660.  doi:10.3969/j.issn.0438-1157.2014.09.047
    Abstract ( 384 )   PDF (618KB) ( 280 )  
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    A novel energy efficiency evaluation index, exergetic efficiency, was proposed to evaluate the performance of magnetic refrigerator rationally and compensate for the limitation in evaluating magnetic refrigerator system with available two indexes, temperature span and cooling capacity. To testify the feasibility of exergetic efficiency evaluation indexes, the experimental data by University of Victoria in the form of temperature span-heat source temperature curve and experimental data by Technical University of Denmark in the form of temperature span-cooling capacity curve were converted to the temperature span-exergetic cooling capacities. Furthermore an experimental platform was established based on Sichuan University magnetic refrigerator prototype. With the heat source temperature controlled at 25, 27 and 30℃, performance parameters of refrigerator such as cooling capacity, temperature span, cooling exergy and exergetic efficiency were obtained. Experimental results indicated that the cooling capacity of the magnetic refrigerator prototype could reach 240 W and its maximum cooling exergy was 3.26 W at heat source temperature 30℃ and 6 r·min-1. With the efficiencies of motor loss, mechanical loss, hysteretic loss and eddy current loss ignored, the peak exergetic efficiency was 0.039.
    Flow and purification effect of heavy metal-containing materials in zinc ore smelting process
    WANG Xueqian, MA Yixing, SHI Yong, WANG Ping, LAN Yi, GUO Xiaolong, WANG Langlang, NING Ping
    2014, 65(9):  3661-3668.  doi:10.3969/j.issn.0438-1157.2014.09.048
    Abstract ( 236 )   PDF (571KB) ( 234 )  
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    Investigation and evaluation for flow and purification effect of heavy metal-containing materials in zinc smelting processes are important and can provide important basic data for controlling heavy metals in the metallurgical off-gas. Heavy metals involved in the materials of zinc ore smelting and metallurgical off-gas were analyzed by XRF, ICP-OES, ICP-MS and double light display mercury analyzer. The results show that after zinc fine ore roasting, 58% Pb and 75% Cd enter into solid materials of zine calcine and dust, 52% As and about 100% Hg flow into metallurgical off-gas. After acid washing and electrostatic demisting, the removal of Pb, Hg, Cd and As are 78.6%, 35%, 90.9% and 83.2% respectively. After deep removal of mercury by Boliden-Norzink technology, the Hg removal is 90.1%. Based on the characteristics mentioned above for heavy metals flow and purification effect, it should be considered that dust removal process must be enhanced to remove effectively Pb and Cd in the metallurgical off-gas, and technology improvement is needed to meet emission standard although the Boliden-Norzink technology has good removal efficiency for mercury.
    Degradation mechanism of silicone rubber in simulated PEM fuel cell environment
    LI Guo, TAN Jinzhu, GONG Jianming, JIA Wenhua
    2014, 65(9):  3669-3675.  doi:10.3969/j.issn.0438-1157.2014.09.049
    Abstract ( 321 )   PDF (900KB) ( 206 )  
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    Elastomer material gasket as an important component works in proton exchange membrane (PEM) fuel cell under moist, acidic conditions. The evolution process of the material's chemical degradation plays a fundamental role in studying the performance of mechanical seal gasket material and its life prediction. The chemical process of the elastomer material was analyzed by using X-ray photoelectron spectroscopy (XPS). The degradation mechanism was mainly molecular chain scission in the backbone and side chain and hydrolysis of crosslinking.
    Grading of dry-bulb and wet-bulb temperature allowances based on characteristics of performance curves
    ZHANG Zhongbin, DU Kai, HUANG Hu, ZHANG Ruonan
    2014, 65(9):  3676-3679.  doi:10.3969/j.issn.0438-1157.2014.09.050
    Abstract ( 418 )   PDF (1457KB) ( 364 )  
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    Based on performance test results, characteristics of cooling capacity (CC) and energy efficiency ratio (EER) change with indoor dry-bulb and wet-bulb temperatures (D&WBT) are examined. By applying corrected Akaike information criterion, best fit 3D surface equations of CC and EER are determined to obtain their variation gradients and corresponding intervals of gradient extrema. Based on the classification principle of keeping the maximum (minimum) EER variation rates between neighboring classes equal, D&WBT allowances in national standard are classified into three classes by using nonlinear classification, with the corresponding range of D&WBT in the union set of the intervals of gradient extrema of CC and EER as Class A, and the current D&WBT allowances set in the national standard as Class C. As an illustration of this new method, indoor D&WBT allowances under the cooling working condition are classified into Class A, B and C. The results show that the EER variation rate in Class A is as low as 1.04%, while that in Class C is 5.19%. It can be concluded that classified D&WBT allowances are more effective in evaluating the performance of a unit and valuable as a reference for revision of the national standard.
    Coal tar pyrolysis to acetylene in thermal plasma
    LI Xuan, HAN Jiantao, WU Changning, GUO Yi, YAN Binhang, CHENG Yi
    2014, 65(9):  3680-3686.  doi:10.3969/j.issn.0438-1157.2014.09.051
    Abstract ( 265 )   PDF (470KB) ( 196 )  
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    The pyrolysis of coal tar using thermal plasma provides a direct and cleaner route to produce acetylene with low hazardous emission, since the ultra-high temperatures and concentrated active species in thermal plasma can easily decompose solid/liquid/gas feedstock into smaller molecules. Experiments were carried out in a lab-scale thermal plasma test platform to investigate the effects of key operating conditions including the sample inject temperature, plasma atmosphere, and coal tar specific enthalpy on the performance of coal tar pyrolysis. The results demonstrated that coal tar can be rapidly cracked to acetylene and other light gases in the thermal plasma reactor. The viscosity of coal tar can be decreased by pre-heated, thereby increasing the mix efficiency between coal tar and thermal plasma jet. The increased hydrogen concentration in plasma working gases improves the coal tar conversion and the yield of acetylene, and reduces coking as well. Higher specific input power of coal tar leads to higher coal tar conversion, acetylene yield and the yields of light gases. 86.3% coal tar conversions, 24.6% acetylene yields and 51.7% yield of light gases were obtained in the optimal experiment. In addition, plasma pyrolysis process can generate ethylene as by-products, and the concentration ratio of ethylene to acetylene can be used to predict the gas reaction temperature.
    Experiments and reaction simulation for SO2 inhibition on de novo formation of PCDD/Fs
    FU Jianying, CHEN Tong, WU Hailong, LIN Xiaoqing, LU Shengyong, LI Xiaodong
    2014, 65(9):  3687-3693.  doi:10.3969/j.issn.0438-1157.2014.09.052
    Abstract ( 441 )   PDF (788KB) ( 223 )  
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    The objective of this article is to study the inhibition characteristics of SO2 on de novo formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) at various temperatures and to explore its inhibition mechanism by simulation of reaction process utilizing HSC Chemistry 6.1 software. Model fly ash and flue gas (10%O2/5%H2O/85%N2) were used as materials of the de novo formation of PCDD/Fs in a temperature range of 200-400℃. SO2 of concentration 200 mg·m-3 was added as inhibitor in inhibiting experiments. The suppression rate and homologue distribution of PCDD/Fs were analyzed to find SO2 inhibiting characteristics. The results showed that the control ability of SO2 was obvious and became stronger along with increase of temperature. Both total suppression rates and toxic equivalent concentration of PCDD/Fs increased with temperature, at 200℃ both below 20%, at 300℃ 75.6% and 77.3%, and at 400℃ up to 89.2% and 80.5% respectively. SO2 caused a lower-chlorinated distribution of PCDD/Fs, especially for PCDDs. At higher temperature, SO2 restrained chiefly PCDFs while at lower temperature PCDDs was mainly inhibited. Besides, SO2 showed selective inhibition for dioxin isomer. At 300℃ de-chlorination of high-chlorinated PCDFs, like HpCDF and OCDF, made 2,3,7,8-TCDF increase. Based on the computation for Gibbs free energy of pivotal reactions and their equilibrium composition, SO2 preferentially reacted with CuCl2, and CuSO4 formed had no catalytic activity. Then, reaction of SO2 with Cl2 made decrease of chlorine source. So, formation of PCDD/Fs was brought down. The results of reaction simulation could not only verify and replenished the sulfur inhibition mechanism existed but also could be an effective and creative method for exploring inhibition mechanism of different kinds of inhibitors like nitrogen-compounds. This could help develop high-effective inhibitors and apply in municipal solid waste incinerator practically.
    Cathode performance in long-term operation of microbial fuel cells
    PAN Bin, SUN Dan, YE Yaoli, GUO Jian, HUANG He, CHENG Shao'an
    2014, 65(9):  3694-3699.  doi:10.3969/j.issn.0438-1157.2014.09.053
    Abstract ( 284 )   PDF (3660KB) ( 546 )  
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    Cathode performance will gradually decrease during long-term operation of microbial fuel cells (MFCs), to answer why cathode performance decrease is of significant for practical application of MFCs. In this paper, nickel foam air-cathodes were used in a MFC to search the reason causing the degradation. It was found that power density of MFC with a nickel foam air-cathode was 22% less for after 4 months operation than for after 1 week operation. Electrode polarization curves measured showed that cathode performance degradation was the main reason leading to decrease in power density. At -0.2 V (vs Ag/AgCl), current density of a new cathode was 12.3 A·m-2, and decreased to 4.2 A·m-2 after 4 months operation. Cathode performance decreased with increase of operation time, which showed mainly in the high current range [>-0.05 V (vs Ag/AgCl)]. Scanning electron microscope (SEM) images indicated that there was no biofilm on cathode surface, implying that the decrease of oxygen diffusion rate through cathodes was the main reason causing the decrease of cathode performance. From energy dispersive spectrometer (EDS) measurement it was found that there was phosphate precipitation inside the cathode after 4 months operation. These results indicated that salt precipitation increased with increase of operation time could clog micro-pores of cathode and decreased oxygen diffusion rate, leading to degradation of cathode performance.
    Degradation of humic acid in water by single- and dual-frequency ultrasound methods
    ZHAO Li, YANG Yanling, LI Xing, ZHOU Zhiwei, ZHANG Yang, MA Changhong
    2014, 65(9):  3700-3704.  doi:10.3969/j.issn.0438-1157.2014.09.054
    Abstract ( 737 )   PDF (474KB) ( 342 )  
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    To understand the degradation of humic acid in simulated water a series of static experiments assisted with ultrasound were done at various energy density of ultrasound produced by both single-frequency (68 kHz, 80 kHz, 100 kHz, 125 kHz and 160 kHz) and dual-frequency (X-Y axial orthogonal 80/125 kHz and 80/160 kHz and X-X axis parallel 68/100 kHz and 125/160 kHz) ultrasound irradiation system. The degradation of dissolved organic carbon (DOC) and trihalomathame precursors (THMFP) were measured. The main results obtained are as follows: for the same energy density of sound, the degradation efficiency is better for low frequency (68 kHz and 80 kHz) than for high frequency ultrasound (100 kHz, 125 kHz, and 160 kHz), dual-frequency is superior to single-frequency, and X-Y axial orthogonal ultrasound excels X-X axis parallel. The best result for degradation of COD and THMFP is obtained in 25 min by using X-Y axial orthogonal combination of 80/160 kHz ultrasound, and is 32.6% and 66.6% respectively.
    Synthesis, characterization and curing characteristics of single benzoxazine containing DOPO based on bisphenol A
    LIU Jianhua, SHI Tiejun, XU Guomei, WANG Quan, WANG Qidong
    2014, 65(9):  3705-3711.  doi:10.3969/j.issn.0438-1157.2014.09.055
    Abstract ( 335 )   PDF (631KB) ( 345 )  
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    Double benzoxazine based on bisphenol A(DBOZ)was synthesized from bisphenol A, aniline and paraformaldehyde, and the single benzoxazine containing DOPO based on bisphenol A(DBDO)was synthesized from DBOZ and DOPO. FT-IR, NMR (1H NMR and 13CNMR) were used to characterize the chemical structure of DBOZ and DBDO. Curing characteristics were studied with DSC and thermostability was studied with TG. In N2 atmosphere, the ring opening polymerization of DBOZ took place at about 205℃, and initial decomposition temperature was 312℃. At 373℃, the fastest decomposition was achieved. At 800℃, carbon residue was 37.19%. In N2 atmosphere, initial decomposition temperature of DBDO was 353℃. At 443℃, the fastest decomposition was achieved. At 800℃, carbon residue was 39.60%.
    Synthesis and properties of novel latent curing agent
    WANG Quan, SHI Tiejun, YU Fu, LIU Jianhua, ZHOU Xun
    2014, 65(9):  3712-3717.  doi:10.3969/j.issn.0438-1157.2014.09.056
    Abstract ( 812 )   PDF (689KB) ( 1678 )  
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    A novel latent curing agent for epoxy resin was synthesized via modifying dicyandiamide (DICY) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) through addition reaction. The chemical structure of the modified DICY was confirmed by FTIR and 1H NMR. The thermal properties of this modified DICY and its epoxy curing system were evaluated by DSC and TG. It was found that the melting point of the modified DICY decreased markedly and curing temperature dropped by nearly 40℃. The optimized curing process was also presented. Moreover, latency and flame retardancy of this system was proven, the storage period was more than 100 d and limiting oxygen index (LOI) was 22.
    Synthesis of SBA-15/Ni/TiO2/CNTs composites and their photocatalytic activities
    SUN Xiuli, CHEN Aiping, LÜ Hui, HE Hongbo, HE Tiantian, LIN Qizhi, LI Chunzhong
    2014, 65(9):  3718-3723.  doi:10.3969/j.issn.0438-1157.2014.09.057
    Abstract ( 266 )   PDF (4057KB) ( 357 )  
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    SBA-15/NiO/TiO2 nanocomposites were prepared by coating nano-TiO2 doped with nickel on SBA-15 support using the sol-gel method. Then carbon nanotubes (CNTs) were grown by in-situ chemical vapor deposition (CVD) on the surface of the SBA-15/NiO/TiO2 with metallic nickel reduced in TiO2 as catalyst. The prepared SBA-15/Ni/TiO2/CNTs nanocomposite photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, UV-Vis absorption spectroscope and Raman spectra. The photocatalytic activities of the samples were investigated by the photocatalytic degradation of methylene blue. The photocatalytic activities of SBA-15/Ni/TiO2/CNTs increased significantly in comparison with SBA-15/NiO/TiO2. The photocatalytic activities of the nanocomposite by twice coating with TiO2 doped with nickel on SBA-15 was also higher than once coating.
    CO2 carbonation of calcium acetate derived from acidolysis of natural CaCO3 for recycling of acetic acid and production of precipitated calcium carbonate
    YANG Zheng, YUE Hairong, ZHOU Xiangge, LIANG Bin, XIE Heping
    2014, 65(9):  3724-3731.  doi:10.3969/j.issn.0438-1157.2014.09.058
    Abstract ( 632 )   PDF (3414KB) ( 455 )  
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    Acetic acid dissolution of limestone for formation of cavity is a kind of environmental approach to fabricating underground storage and preparing precipitated calcium carbonate. This process is an integrated technology consisting of acetic acid dissolution of limestone and CO2 carbonation of calcium acetate. The kinetics of limestone acidolysis with acetic acid was investigated. Orthogonal experiments were conducted with emphasis on operation conditions (i.e., concentration of calcium acetate, pressure of CO2, reaction temperature, and reaction time) of the carbonation reaction. The highest conversion of calcium acetate (23.13%) was achieved at the calcium acetate concentration of 0.631 mol·L-1, CO2 pressure of 5 MPa, reaction temperature of 80℃ and reaction for 50 min. The product of calcium carbonate was analyzed and could meet the requirements of Chinese national standard.
    Sintering mechanism of ceramics prepared from BOF slag
    WANG Wei, DONG Hanqiong, WANG Biao, ZHAO Yunchao, WANG Kai
    2014, 65(9):  3732-3737.  doi:10.3969/j.issn.0438-1157.2014.09.059
    Abstract ( 257 )   PDF (1273KB) ( 210 )  
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    In order to study the sintering mechanism and kinetics of buildings ceramics prepared from basic oxygen furnace (BOF) slag, the BOF slag with different grain sizes as the main materials were mixed with some additives to improve the properties of sintering, and ceramic tiles with good performance were made. Sintering mechanism was studied with respect to ceramic tiles samples deformation and changes of density before and after sintering, and sintering activation energy of the BOF slag ceramic tiles was calculated. Crystallization kinetics of the BOF slag ceramic tiles was studied with differential thermal analysis and scanning electron microscopy. The smaller the grain size of raw material, the easier the sintering and the lower the sintering temperature. The broad crystallization peak in the differential thermal analysis indicated surface crystallization, whereas the sharp peak indicated bulk crystallization. The current work is useful for harmless processing and recycling of the BOF slag on a large scale.
    Anticorrosion property of polyaniline doped twice with functional acid
    YANG Xian, YANG Xiaogang, MA Xinqi
    2014, 65(9):  3738-3743.  doi:10.3969/j.issn.0438-1157.2014.09.060
    Abstract ( 375 )   PDF (579KB) ( 283 )  
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    As polyaniline (PANI) has unique doping and dedoping characteristics, good morphology nanofibers can be synthesized under specific reaction conditions and new nanomaterials with special anticorrosion functional groups can be prepared via the dedoping and twice doping process. PANI nanofibers doped with sulfuric acid were dedoped by ammonia solution, and based on this dedoped PANI, twice doped PANI were prepared in phosphoric acid, p-toluene sulfonic acid and tartaric acid system respectively. The structure of doped and twice doped PANI was characterized by FT-IR spectrometer and UV-Vis absorption spectrometer. An electrochemical workstation was used to record the open circuit potential (OCP) and the electrochemical impedance spectroscopy (EIS) of polyaniline/epoxy composite coatings, and their anticorrosion mechanism were investigated theoretically. FT-IR spectra and UV-Vis spectra indicated that the state of PANI was doped PANI in its emeraldine salt form. The electrochemical testing results showed that every coating had certain anticorrosion performance and the impedance value suffered a significant decrease at the beginning of immersion because the coating was permeated by the corrosive medium. The impedance value of twice doped PANI and doped PANI tended to stabilize after immersion for 22 d and 60 d respectively, the protection effect could be explained by the assumption that metallic cations formed a passivating complex with the dopant anion released from PANI, which improved the barrier property of PANI coating and slowed down the further corrosion of the metal. PANI doped twice with functional acid had better anticorrosion performance than doped state and twice doped PANI had higher impedance. PANI doped twice with tartaric acid had the highest impedance, the impedance value was 3.48×107 Ω·cm2 after immersion for 120 d, an order of magnitude higher than its doped state.