Please wait a minute...
Table of Content
05 August 2018, Volume 69 Issue 8
    A review on effects of extracellular polymeric substances on contaminants fate & transport in soil and water environment
    WU Yuhui, YANG Yuesuo, ZHAO Chuanqi, ZHANG Xi, CHEN Yu, XU Bin
    2018, 69(8):  3303-3317.  doi:10.11949/j.issn.0438-1157.20180182
    Abstract ( 187 )   PDF (2054KB) ( 175 )  
    References | Related Articles | Metrics

    There are a large number of microorganisms in the soil and water environment. The extracellular polymeric substances (EPS) attached on their surfaces play an important role in the migration and transformation of heavy metals and organic contaminants. This paper aims at protecting the water and soil environment, improving the level of problem-solving of science and engineering in remediation efficiency of contaminated water and soil. Various studies conducted so far about composition and structure of EPS, factors affecting the EPS secretion of microorganism, the EPS extraction methods and biodegradability of EPS were reviewed. The microscopic mechanism of EPS in biodegradation and removal of metals and toxic organic substances in soil and water environment was systematically analyzed. The further perspectives of EPS research in soil and water environment are proposed in considering the current problems and issues in the related studies, and particularly in supporting bio-chemical remediation engineering of contaminants using the EPS scientific understanding.

    Progress in biomass gasification power generation technology
    CHANG Shengqiang, LI Wangliang, ZHANG Xiaoyu, MA Liqiang, LU Changbo, AN Gaojun
    2018, 69(8):  3318-3330.  doi:10.11949/j.issn.0438-1157.20180235
    Abstract ( 254 )   PDF (501KB) ( 193 )  
    References | Related Articles | Metrics

    The depletion of fossil energy and environmental pollution gradually become the barriers of social development. To promote the sustainable development of society, it is urgent to seek green and clean energy. Because of its renewability, abundance in raw materials, cleanness and low-carbon characteristics, biomass energy has great potential for industrial application. Biomass gasification-power generation technology, one of the methods of biomass utilization, can replace the traditional fossil energies and avoid environmental pollution. This paper reviews the research progress of biomass gasification-power generation technology, including gasification equipment, life cycle assessment and power generation technology, etc., which can provide the references for the development of biomass gasification-power generation technology.

    van der Waals' force effect on viscoelasticity of Lennard-Jones fluid
    JI Jiayuan, ZHAO Lingling
    2018, 69(8):  3331-3337.  doi:10.11949/j.issn.0438-1157.20180133
    Abstract ( 124 )   PDF (1339KB) ( 104 )  
    References | Related Articles | Metrics

    In order to reveal the influence of van der Waals' force on Lennard-Jones fluid viscoelasticity from the micro scale, equilibrium molecular simulation method was used to research the liquid-solid coexistence Lennard-Jones fluid of 30 conditions in the range of ρ*=0.85-1.0 and T*=0.6-1.5 in this study. First, the viscosity of argon is simulated by this model and the results are consistent with the experimental value of the error within 6.69%, which verifies the expansibility of the model to the real substance. Then the liquid-solid coexistence Lennard-Jones fluids simulated, and the accuracy of the simulation in this range is verified by comparing the simulation viscosities with the literature values within the error of 5.16%. Finally, the variation of both static viscoelasticity (viscosity η*, high-frequency shear modulus G*) and dynamic viscoelasticity (storage modulus G'*, loss modulus G"*) were observed from the external factors (temperature and density) and internal factors (Lennard-Jones potential parameters, ε and σ), in addition, the microscopic mechanism of van der Waals' force effect on the viscoelasticity was elaborated as well. The results show that both density increment and temperature decrement lead to the increase of the static viscoelasticity (η*, G*), meanwhile, G'* and G"* in the high frequency region were also increased by the increment of temperature and density, which suggests the enhancement of the viscosity and elasticity. Furthermore, when Lennard-Jones potential parameter, ε or σ increases, the Lennard-Jones fluid tends to be more solidified, this enhances both static and dynamic viscoelasticity and provides a guide to improve the viscoelastic properties of monatomic material in the engineering applications.

    Prediction of thermodynamic properties of n-alkanes based on temperature-corrected force field
    QI Chang, LU Diannan, LIU Yongmin
    2018, 69(8):  3338-3347.  doi:10.11949/j.issn.0438-1157.20180294
    Abstract ( 143 )   PDF (734KB) ( 82 )  
    References | Related Articles | Metrics

    Aim to accurately predict the thermodynamic properties of n-alkanes and their mixtures at different temperature, in this paper, the non-bond Lennard-Jones (L-J) interaction parameter, ε, was optimized by using n-C4-C10 as the training set and all-atom molecular dynamics simulations. Here an empirical relationship between the L-J parameter (ε) and the reduced temperature (Tr) and carbon atomic number of n-alkanes (NC) was obtained. According to above-mentioned relationship, the values of ε at different temperatures were successfully calculated. Further, the properties of viscosity, density and diffusion coefficient of different n-alkanes and their mixtures were predicted using traditional and non-equilibrium molecular dynamics simulations with all-atom OPLS-AA force field corrected by temperature-dependent ε. Compared with previous theoretical prediction values and experimental data, the prediction with temperature-dependent ε showed that the physical properties of n-alkanes and their mixtures predicted by this method were in the best agreement with the experimental values. The relative deviations between the predicted values of density, viscosity and diffusion coefficient and their corresponding experimental counterparts were less than 2%, 5% and 10%, respectively. The new predicted values are significantly superior to those predicted by both other theoretical methods and molecular dynamics simulations with the original OPLS-AA force field. Therefore, the established temperature-dependent force field has important practical application value for accurately predicting the thermodynamic properties of n-alkanes and their mixtures by molecular dynamics simulations.

    Experimental and numerical investigation on effect of particle characteristics on performance of plate-type impact separator
    FENG Lele, WANG Jingyu, WU Yuxin, ZHANG Hai, ZHANG Man, LÜ Junfu, YUE Guangxi
    2018, 69(8):  3348-3355.  doi:10.11949/j.issn.0438-1157.20180112
    Abstract ( 133 )   PDF (874KB) ( 129 )  
    References | Related Articles | Metrics

    Particle-wall collision and particle-gas interaction have significant influence on the separation performance of the impact separators. The experiments were carried out to study the particle-wall collision behaviors. A particle-wall collision model with average restitution coefficient was proposed. The restitution coefficient and friction coefficient were described as a function of collision angle, and this function varies for different particles. The shape of particles was measured by microscope. The glass beads are very close to sphere, while the coal particles are quite irregular. Thus spherical particle drag force model was adopted for glass beads, and non-spherical particle drag force model was adopted for coal particles. The numerical investigations on the separation performance and gas-solid flow in the plate-type impact separators were conducted with the particle-wall collision model and non-spherical drag force model. The simulation results show good agreements of both overall and grade separation efficiency with the experimental results. The separation prediction of particles with large Stokes number is sensitive to the particle-wall collision model, while that of particles with small Stokes number is sensitive to the particle-gas drag force model.

    Central sheet formation mechanism and dynamic characteristics in simultaneous impact of multiple droplets on liquid film
    LIANG Gangtao, ZHANG Tianyu, CHEN Hongliang, YU Haibing, SHEN Shengqiang
    2018, 69(8):  3356-3363.  doi:10.11949/j.issn.0438-1157.20180179
    Abstract ( 111 )   PDF (945KB) ( 169 )  
    References | Related Articles | Metrics

    This study employed the method of coupled level set and volume of fluid (CLSVOF) to simulate simultaneous impact of multiple droplets on a liquid film three-dimensionally, and focused on the splashing process with the implement of Gaussian distribution to generate perturbation on liquid phase. The formation and break-up mechanisms of the central sheet and the formation mechanism of the column jet were revealed through analyzing pressure and velocity distributions after impingement. The effects of impact Weber number, film thickness and droplet interval were discussed. It is shown that the splashing characteristics can be well predicted with the use of Gaussian distribution on liquid phase. After the neck-jet or crown liquid sheet contacting with each other, a great pressure gradient is produced in the contact region, which leads to production of the upward-moving central liquid sheet with the conjunct motivation of fluid kinematic discontinuity and breaks up under the effects of fluid instability and gas vortex. The central sheet height increases with increasing Weber number and film thickness, or with decreasing droplet interval.

    Compensation method for slug flow measurement in shale gas well using Venturi tube
    NIU Shouzi, WU Haitao, XU Ying, LI Jianli, ZHANG Tao
    2018, 69(8):  3364-3372.  doi:10.11949/j.issn.0438-1157.20180129
    Abstract ( 101 )   PDF (705KB) ( 129 )  
    References | Related Articles | Metrics

    The flowrate measurement technology for the wet gas with intermittent slug flow was developed. The dimensionless analysis and the Chisholm correlation were applied to build the overreading correlation and compute the liquid flow rate. The flowrate of intermittent slug was regarded as the sum of the flowrate in the film region and the slug region. The wet gas measurement system was applied directly in the film region. The gas and liquid flowrates in the slug region were obtained by the slug closure model. By studying the effect of the slug on the pipe pressure and differential pressures of Venturi tube, a new method was carried out to determine liquid slug. Logistic regression was attached with it to improve the accuracy of the method. Industrial field testing for 19 d, the results showed that, due to the use of slug flow compensation technology, the cumulative deviation of gas flowrate was improved from 14% to 1.08% and the cumulative deviation of liquid flowrate was improved from -57% to -11%.

    Pressure drop of gas-liquid two phases parallelly flowing down through a stacked sieve plate packing
    JIANG Peng, WANG Kun, QIAO Min, LI Junfeng, XUE Yunxiang, HUANG Weixing
    2018, 69(8):  3373-3382.  doi:10.11949/j.issn.0438-1157.20180056
    Abstract ( 155 )   PDF (640KB) ( 121 )  
    References | Related Articles | Metrics

    Stacked sieve plate packing, a newly developed packing, has been successfully used in degassing column of nuclear power plant. For the purpose of engineering design, systematic experiments were carried out to investigate resistance characteristics of gas-liquid co-currents flowing down through this packing under a broad range of gas-liquid flowrate. 6 packings were used, including three hole diameters of 6 mm, 10 mm, 14 mm and their corresponding square and triangle hole distributions. Different hole diameters had different spacing between holes and plates. Measurement of pressure drop were analyzed to understand influence of flowrates and geometrical parameters, e.g., hole diameter, hole distribution, hole spacing and plate spacing, on flow behaviors and pressure drop characteristics of gas-liquid two phases parallel through the packings. Based on empirical formula of perforated plate resistance coefficient, a new correlation of resistance coefficient for single phase (gas) flowing through stacked sieve plate packing was developed. The model correctly reflected influence of all geometrical parameters in good agreement with experimental results with a deviation of less than 5%. Further, based on homogeneous flow model, a prediction model of two-phase pressure drop of gas and liquid flowing through stacked sieve plate packing was proposed. This new two phase pressure drop model had good prediction with less than 10% deviation. This work provides valuable basis not only for the design of stacked sieve plate packing column, but also for further study of mass transfer in this new packing.

    Three-dimensional electrical capacitance tomography in rectangular spouted bed
    SUN Yang, YANG Daoye, LIU Dazhen, FENG Wenxuan, GU Muyang
    2018, 69(8):  3383-3389.  doi:10.11949/j.issn.0438-1157.20180086
    Abstract ( 83 )   PDF (2948KB) ( 89 )  
    References | Related Articles | Metrics

    A 32-electrode electrical capacitance volume tomography (ECVT) system was designed to investigate the characteristics of particles flow in rectangular spouted bed. To calculate the sensitive field, the finite element simulation model was established. The sensor characteristics were simulated and analyzed. The accuracy of sensitive field was verified by imaging. By making scale solid model, the capacitance of electrode couples attached around the model was carried out by using the system. Linear back projection (LBP) algorithm was adopted to reconstruct the distribution of three-dimensional dielectric constant in the bed. The results indicated that the 32-electrode ECVT system can detect the regular movement of particles from static to circular in the spouted bed effectively, which provided another effective method for the research of motion characteristics of particles in the spouted bed.

    Influence of twisty flow heat exchanger's structural parameters on flow field and temperature field
    GU Xin, LUO Yuankun, XIONG Xiaochao, WANG Ke, TAO Zhilin
    2018, 69(8):  3390-3397.  doi:10.11949/j.issn.0438-1157.20171612
    Abstract ( 115 )   PDF (648KB) ( 114 )  
    References | Related Articles | Metrics

    Periodic whole cross-section computation models of twisty flow heat exchanger and segmental baffle heat exchanger are established respectively. The heat transfer coefficient, flow resistance and thermal performance are studied with CFD simulation. The influence of inclination angle of trapezoidal baffles, baffles width, baffles pitch and number of baffles on the heat transfer performance in the twisty flow heat exchanger was studied. The results showed that the inclination angle of trapezoidal baffles and baffles pitch have a significant effect on heat transfer performance, the effect of baffles width is secondary, and the number of baffles have no significant effect. When the thermal performance factor TEF of twisty flow heat exchanger reaches the best, compared to segmental baffle heat exchanger, the pressure drop decrease by 42.5% to 46.9%, the TEF is improved by 7.2% to 14.1%. The results of this paper provide a new scheme of the shell and tube heat exchanger for structure optimization and heat transfer enhancement.

    Drag characteristics of air-mixed heavy oil in horizontal pipes
    JING Jiaqiang, YIN Ran, MA Xiaoliang, SUN Jie, WU Xi
    2018, 69(8):  3398-3407.  doi:10.11949/j.issn.0438-1157.20180088
    Abstract ( 122 )   PDF (780KB) ( 85 )  
    References | Related Articles | Metrics

    Based on visualizable fluid circuit, a lab-scale setup for drag reduction of aerated heavy oil was designed. Two heavy oil models mixed with air were experimentally studied for flow resistance characteristics in horizontal pipe. Photos were taken to capture fluid flow patterns in pipe at various air liquid ratios. The drag reduction effect of air on heavy oil at different conditions was analyzed and a corresponding pressure drop prediction model was established. At gas-liquid ratios ranged from 0 to 15, six flow patterns were observed, i.e., bubbly flow, plug flow, stratified flow, slug flow, annular flow and spray flow. The drag reduction rate of 220# and 440# model oils reached peak at 48.19% and 33.76% at air liquid ratio of 1.17 and 0.96 respectively. When the ratio was in a range of 0.9 to 1.2, drag reduction rate of both oils could be maintained at 20%. The mechanism of drag reduction was attributed to that air changed interface from oil-oil to oil-gas-oil such that shear stress between layers of mixed phase could be lowered. The Dukler's method is not applicable to gas-liquid two-phase flow of high viscosity oil, however, the established heavy oil-gas two-phase pressure drop model predicts well with measurement which has less than 20% average relative standard error.

    Numerical simulation of fully developed liquid-solid flow in vertical narrow channel
    HU Rentao, REN Libo, WANG Dewu, LIU Yan, ZHANG Shaofeng
    2018, 69(8):  3408-3417.  doi:10.11949/j.issn.0438-1157.20180189
    Abstract ( 74 )   PDF (699KB) ( 83 )  
    References | Related Articles | Metrics

    Water-glass bead system and Euler-Euler dual-fluid model were used to simulate liquid-solid two-phase flow at fully developed stage of a vertical narrow channel with a dimension of 240 mm in length, 12 mm in width and 1800 mm in height. The results show that the liquid-solid two-phase flow enters full development stage after 0.7 m in vertical direction of the narrow channel. At cross section of the full development stage, particle velocity and concentration in both wide and long axial directions were high in central region but low near wall area. With increase of inlet liquid velocity, solid particle velocity increased at each position of the cross section, while particle concentration decreased at center but increased near wall. With increase of initial solid phase volume fraction, solid particle concentration increased at each position of cross section, while particle velocity decreased slightly at center but increased slightly near wall. Particle thickening effect was observed in the region near three wall junction at both long axial ends of the channel cross-section. In the region of large particle velocity distribution and high concentration gradient along the wide direction of channel cross-section, non-dimensional proportion increased with increase of inlet liquid velocity but decreased with increase of initial solid volume fraction.

    Composite model of heat transfer and phase transition with high gas and liquid density ratio
    LIU Bingbing, WANG Mingyu, GAO Hongtao, ZHANG Shaojun
    2018, 69(8):  3418-3427.  doi:10.11949/j.issn.0438-1157.20180021
    Abstract ( 84 )   PDF (4049KB) ( 59 )  
    References | Related Articles | Metrics

    Based on lattice Boltzmann thermal model and large density ratio model, a phase transition source term was introduced into two-phase density distribution control function to describe effect of temperature field on gas-liquid phase transition. A composite lattice Boltzmann thermal model, which can describe heat transfer and phase transition at gas-liquid ratio up to 2778, was proposed to study two-phase heat transfer mechanism. Numerical instability caused by extremely large gas-liquid density ratio was resolved by regress correction of pressure velocity distribution function. Double bubble rising movement and the surrounding temperature field distribution in lithium bromide solution was simulated using the model. Upper bubble temperature was higher than that of lower bubble prior to collision during moving up. Upon coalescence, liquid bridge between the two bubbles was open, heat transfer started and temperature inside the bubble became uniform. The volume of the double bubbles decreased first and then increased with maximum at time of two bubbles collision. After bubble coalescence, the volume gradually decreased and eventually stabilized to certain value. The larger the initial bubble volume is, the greater the velocity of the bubble rises.

    New model for measuring stratified gas-liquid flow by Chisholm-model-based V-cone flowmeter
    HE Denghui, CHEN Senlin, BAI Bofeng
    2018, 69(8):  3428-3435.  doi:10.11949/j.issn.0438-1157.20180136
    Abstract ( 97 )   PDF (639KB) ( 68 )  
    References | Related Articles | Metrics

    Large errors are usually observed when Chisholm model is used in V-cone flowmeter to measure stratified gas-liquid flow rate. Three V-cone flowmeters with throttle ratios of 0.55, 0.65 and 0.75 were used to study stratified gas-liquid flow at gas volume fraction of more than 95%. The effects of gas and liquid flow rates, operating pressure and throttle ratio on correction factor C of the Chisholm model were analyzed and new model for measuring stratified gas-liquid flow was developed. Correction factor C was monotonically decreased with increase of Lockhart-Martinelli, XLM, but was hardly affected by pressure and the gas densiometric Froude number. However, C was somehow affected by throttle ratio. The relationship between C and XLM was obtained and new models for three V-cone flowmeters to measure stratified flow were developed. The relative standard error of the predicted gas flow rate was with ±3.0% for V-cone flowmeters with throttle ratios of 0.55 and 0.65 under confidence level of 94.6% and 88.6%, respectively, while that was with ±4.0% under 91.7% confidence level for V-cone flowmeter with throttle ratio of 0.75.

    Experimental study on pore characters effect on drainage process
    MA Bin, MA Yuezheng, SHI Lin
    2018, 69(8):  3436-3442.  doi:10.11949/j.issn.0438-1157.20171502
    Abstract ( 75 )   PDF (772KB) ( 67 )  
    References | Related Articles | Metrics

    Macro drainage characters were determined by micro drainage features in pore scale. They are inhomogeneous everywhere in different directions. Three distinctive Hele-Shaw cells were designed to study the effects of pore structure on drainage process. The pore structure characters were elucidated by several parameters including pore angle, critical ratio (the ratio of the max pore diameter to the min throat size), tortuosity and porosity. The results show that when displacement velocity is the same, larger pore angle or smaller tortuosity results in greater non-wetting phase (dodecane and hexadecane) saturation; when displacement velocity is not the same, larger displacement velocity makes greater non-wetting phase saturation. Critical ratio and porosity are not the decisive factors; their effects on drainage process are evaluated by their values and other pore structure parameters, such as pore angle and so on. When pore angle and displacement velocity are the same, smaller viscosity ratio pairs tend to have a higher drainage effect.

    MP-PIC simulation of particle clusters in fast fluidized bed risers
    SUN Ziwen, CHEN Dailin, ZHONG Wenqi, YU Ai-Bing
    2018, 69(8):  3443-3451.  doi:10.11949/j.issn.0438-1157.20171666
    Abstract ( 85 )   PDF (2680KB) ( 74 )  
    References | Related Articles | Metrics

    A three-dimensional Eulerian-Lagrangian model, based on MP-PIC method, was developed to simulate particle clusters in fast fluidized bed risers. In the model, gas phase was simulated by large eddy simulation (LES), real particles were displaced by numerical-particles and particles was described by Newton movement equations, drag between gas and particles was calculated by Gidaspow model, and normal stress of particles was calculated and interpolated into Eulerian grids to describe particle contraction. The model was used to simulate gas solid movement in a 3D fast fluidized bed riser with dimension of height H=3 m and diameter d=0.1 m and adjusted according to experimental data. Cluster characteristics of particles (ρp=2650 kg·m-3 and dp=250 mm) was studied at operational condition of Ug=5.28 m·s-1gas velocity. The results indicate that the MP-PIC simulation can recognize different shapes of clusters, such as stripe-shaped, saddle-shaped and U-shaped, as well as disclose cluster development including formation, expansion, coalescence and breakup. Mean particle concentration distribution of clusters in the riser cross section shows a core-annular structure with low middle and high edge concentrations, which is opposite to mean cluster velocity distribution. The mean particle concentration of clusters decrease while the mean cluster velocity increase with increase of riser height, but the change of both concentration and velocity slows down above certain riser height.

    γ-Valerolactone synthesis from levulinic acid hydrogenation over Ni/ZrO2-SiO2 catalyst
    WANG Jie, ZHANG Yin, GUO Jianjian, ZHAO Lili, ZHAO Yongxiang
    2018, 69(8):  3452-3459.  doi:10.11949/j.issn.0438-1157.20180027
    Abstract ( 88 )   PDF (977KB) ( 97 )  
    References | Related Articles | Metrics

    ZrO2、SiO2 and ZrO2-SiO2 oxide composite supported Ni catalysts with Ni content of 10%(mass) were prepared by incipient impregnation method and characterized by N2 physical adsorption, NH3-TPD, H2-TPR, XRD, TEM. The catalysts were evaluated for liquid phase hydrogenation of levulinic acid. The results showed that levulinic acid was first hydrogenated to 4-hydroxy valeric acid via C=O hydrogenation and γ-valerolactone was then produced by immediate esterification of 4-hydroxy valeric acid. Compared to Ni/ZrO2 and Ni/SiO2 catalysts, Ni/ZrO2-SiO2 catalyst exhibited highest dispersion of metallic Ni and most surface acid sites. As a result, the Ni/ZrO2-SiO2 catalyst demonstrated highest activity for C=O hydrogenation and superior performance for synthesis of γ-valerolactone via levulinic acid hydrogenation. 100% levulinic acid conversion and over 99.9% γ-valerolactone selectivity were achieved under reaction temperature of 200℃ and hydrogen pressure of 4 MPa.

    Falling film crystallization kinetics of paraxylene
    WANG Rui, XU Yanxia, SONG Xingfu, XU Zhigang, YU Jianguo
    2018, 69(8):  3460-3468.  doi:10.11949/j.issn.0438-1157.20180134
    Abstract ( 117 )   PDF (576KB) ( 125 )  
    References | Related Articles | Metrics

    Falling film crystallization is an important production method of paraxylene in industry. The falling film crystallization kinetics of paraxylene was studied based on the fractal and porous media theory. The experimental conditions were optimized by kinetic modeling. The crystallization conditions were feeding speed of 60 ml·min-1, crystallization temperature of -15℃ and raw material precooling temperature of 25℃, and sweating conditions were heating rate 1℃·min-1, and sweating end temperature of 5℃. Under the optimized experimental conditions, the crystal growth rate equation and the liquid entrapment rate equation were built by measuring the amount of paraxylene crystallization and liquid entrapment, and the correlation coefficients were 0.967 and 0.977. The results show that the liquid entrapment rate increases faster, and the volume fraction of the liquid entrapment in the crystal layer increases with the augment of supersaturation, resulting in the increase of porosity in the crystal layer. The establishment of crystal growth rate equation and liquid entrapment rate equation has important significance for the control of the crystal layer growth by adjusting the liquid film supersaturation in the industrial paraxylene production by falling film crystallization.

    Simulation and analysis of a side stream reactive distillation-pervaporation integrated process for ethyl acetate production
    JIN Hao, LU Jiawei, TANG Jihai, ZHANG Zhuxiu, FEI Zhaoyang, LIU Qing, CHEN Xian, CUI Mifen, QIAO Xu
    2018, 69(8):  3469-3478.  doi:10.11949/j.issn.0438-1157.20180154
    Abstract ( 149 )   PDF (562KB) ( 120 )  
    References | Related Articles | Metrics

    Due to the complicated process and huge energy consumption of ethyl acetate production via esterification of acetic acid and ethanol, a reactive distillation and pervaporation integrated process was proposed. The byproduct water was removed from the system through the side stream of the column and membrane modules, which promoted the forward reaction and improved the purity of ethyl acetate. The effect of the process parameters on total annual cost was investigated. The parameters included side stream drawn stage, side stream flowrate ratio, reactive stages, rectifying stages and number of membrane modules. Compared with conventional double-column process, the proposed RD-PV integrated process saved 26.6% energy. Through the investigation, it was found that the price of membrane material had significant effect on the total annual cost of RD-PV integrated process. With the development of pervaporation technology, the RD-PV process would appear economically competitive, when the price of membrane material is lower than 1913 CNY·m-2.

    Phase equilibrium and separation of n-dodecane-toluene-phenol in low temperature coal tar
    ZHANG Haiyong, LIU Qian, LIU Xingkun, ZHANG Xianglan, XIE Qiang, WANG Yonggang
    2018, 69(8):  3479-3487.  doi:10.11949/j.issn.0438-1157.20180032
    Abstract ( 194 )   PDF (560KB) ( 125 )  
    References | Related Articles | Metrics

    The group separation of low temperature coal tar (LTCT) is important for its effective utilization. With n-dodecane, toluene and phenol as model compounds, the liquid-liquid-equilibrium (LLE) of alkane-aromatics-phenol ternary system in LTCT were obtained by experimental method and Aspen Plus simulation. The LLE of typical ternary systems during separation of the mixture by N, N-dimethylformamide (DMF) water solution were also simulated. The results show that the ternary phase diagram simulated by Aspen Plus through UNIF-LL model fit well with experimental data. Toluene as a cosolvent promotes n-dodecane-toluene-phenol to be a homogeneous system. According to the solubility difference of n-dodecane, toluene and phenol in DMF and with the Hansen solubility parameters theory, n-dodecane and toluene can be separated successively from their homogeneous mixture by DMF in which different content of water were added to adjust the polarity of solvent. Based on the optimization of extraction temperature, solvent/oil ratio and water content in solvent, n-dodecane with 93.2% purity was separated by one stage extraction with DMF, and after phase separation, toluene with 93.4% purity was obtained by adding water weighted 30% of DMF to the extract phase at 303K, 1.5 solvent/oil ratio.

    Effect of inlet structure on transient properties of gas flow in cyclone separator
    WANG Lu, ZHANG Xingfang, DONG Zhenzhou, ZHAO Zhongkai, YANG Jingxuan, HAO Xiaogang
    2018, 69(8):  3488-3501.  doi:10.11949/j.issn.0438-1157.20180114
    Abstract ( 158 )   PDF (986KB) ( 165 )  
    References | Related Articles | Metrics

    The processing vortex core phenomenon (PVC) diminished the efficiency of a cyclone in capturing fine particles. In this paper, the numerical simulation method was used to study the motion frequency of vortex core and eccentricity degree from vortex core to geometrical center in a gas-flow field with a spiral inlet. Generally, the surface minimum pressure was regarded as the vortex core, and the PVC phenomenon was swung most heavily at the dust outlet section. Therefore, the variation of minimum pressure over time at dust outlet was analyzed by the fast Fourier transform (FFT), and the location of the vortex core was recorded. The results showed that the frequency and eccentricity degree at the dust outlet were gradually decreased with the increase of volute wrapping angle, and the PVC phenomenon was weakened. While the volute wrapping angle was more than 270°, the PVC phenomenon in the gas-flow field almost disappeared. The influence of the entrance cut-off on the movement characteristics of the vortex core at the dust outlet section would vary depending on the volute wrapping angle. Compared with the symmetry of the inlet structure, the eccentricity degree of vortex core was more strongly related to the energy loss of the down draft. When the energy loss of the downward airflow was greater, the energy getting from outer vortex to inner vortex zones was higher, and upward flow would suffer greater horizontal disturbances. When the energy of the incoming air flow exceeded a certain threshold value, the vortex core oscillation was induced. The vortex core rotation frequency was less affected by the energy loss of the downward airflow.

    Monovalent anions removal by capacitive deionization integrated with monovalent anion permselective exchange membrane
    PAN Jiefeng, ZHENG Yu, DING Jincheng, SHI Wenhui, SHEN Jiangnan, GAO Congjie
    2018, 69(8):  3502-3508.  doi:10.11949/j.issn.0438-1157.20180149
    Abstract ( 193 )   PDF (687KB) ( 149 )  
    References | Related Articles | Metrics

    The objective of this study is to investigate the feasibility of applying capacitive deionization (CDI) integrated with a monovalent anion permselective exchange membrane (PSMCDI) to remove chloride selectivity from a solution of mixed chloride and sulfate ions. Two types of membranes (ASC and ASV) were evaluated for selectivity removal of monovalent and divalent anions. A variety of parameters (anion composition and concentration, pH, operating time, voltage, and flow rate) were investigated to achieve a maximum selectivity. The selectivity for monovalent anions was evaluated by a lab-made MCDI with a model aqueous system (Cl-/SO42-). The results show that the removal amount of anions increased with increasing anion concentration, but the selectivity for monovalent anions (Cl-) decreased. The selectivity also decreased with operating time. For the ASV membrane, a monovalent anion selectivity of 1.6 was obtained under the conditions of 1.2 V operating voltage, 10 min adsorption time and 30 ml·min-1 feed flow rate. The corresponding monovalent anion removal selectivity was 1.4 for the ACS membrane. The results in this study can help in developing the PSMCDI technology, and expand its application for removing monovalent anions from a mixed solution.

    Removal of chromium-containing wastewater by integration treatment of magnetic flocculation and HGMS magnetic-fluid extraction
    DU Jiao, SUN Zongying, GUAN Yueping, ZHANG Zhi, LI Tao, XU Guoli, FAN Qingqian
    2018, 69(8):  3509-3516.  doi:10.11949/j.issn.0438-1157.20171630
    Abstract ( 84 )   PDF (535KB) ( 86 )  
    References | Related Articles | Metrics

    The magnetic separation technology was combined with chemical flocculation and solvent extraction method to synthetically provide a new way of treating chromium-containing wastewater by the application of magnetic flocculation and high gradient magnetic separation (HGMS) for magnetic-fluids extraction.Namely magnetic flocculation method was used to treat high concentration chromium-containing electroplating wastewater once, and the optimal magnetic flocculation conditions were obtained by orthogonal test method:pH 8, the dosage of magnetic Fe3O4 particles 4 g, mixing speed 80 r·min-1, the main flocculant PAFC dosage 6 ml, under which can reduce the chromium concentration in the wastewater from 4325.13 mg·L-1 to 29.8·mg·L-1. After magnetic flocculation treatment, the method of high gradient magnetic-fluids extraction was used in secondary processing, the wastewater was pumped and continuously flowed through two series of high gradient magnetic-fluids extraction devices within seven hours, and the highest extraction rate could achieve 99.4%, average extraction rate could achieve 98.97%, under optimal conditions. Furthermore, chromium concentration could be reduced to 0.31 mg·L-1, which met the national emission standard. Under alkaline conditions, the stripping rate of magnetic fluid was more than 90%, and the regenerated magnetic fluid extraction agent can be reused.

    Association rules based conditional state fuzzy Petri nets with applications in fault diagnosis
    LI Peijie, YANG Bo, LI Hongguang
    2018, 69(8):  3517-3527.  doi:10.11949/j.issn.0438-1157.20180063
    Abstract ( 95 )   PDF (713KB) ( 167 )  
    References | Related Articles | Metrics

    As a knowledge representation model, fuzzy Petri nets can be potentially used in industrial process systems for fault reasoning and diagnosis. The establishment of fuzzy Petri nets model usually demands for a priori knowledge, which discourages the use in practice. To utilize industrial process data effectively, association rules based on conditional state fuzzy Petri nets are proposed, which are subsequently applied to industrial process fault reasoning and diagnosis. Fuzzy rules along with confidences of fuzzy Petri nets are extracted by association rule algorithms of data mining. Key principal components (conditional variables) affecting the confidence are extracted by correlation analysis between variables and conditional states, thus creating the conditional state fuzzy Petri nets. The reverse reasoning of dynamic confidence is performed with the iterative algorithm of the maximal algebra, obtaining the probability of fault occurrence in industrial processes. This approach realizes data driven fault diagnosis, so as enhancing the speed and accuracy of fault diagnosis. A case study on chemical reactions shows the effectiveness of the proposed method.

    Fault detection method based on state space-PCANet
    DONG Shun, LI Yiguo, SUN Shuanzhu, LIU Xichui, SHEN Jiong
    2018, 69(8):  3528-3536.  doi:10.11949/j.issn.0438-1157.20180025
    Abstract ( 172 )   PDF (700KB) ( 101 )  
    References | Related Articles | Metrics

    As a classical algorithm for feature extraction, principal component analysis (PCA) has been widely used in multivariate statistical process monitoring. However, PCA and its various improved methods extracted from original data only one layer of features but no deep layer features. The development of deep learning technology in computer field indicates that deep network structure is beneficial to extraction of data features. Therefore, principal component analysis network (PCANet), a deep learning network structure, was introduced into fault detection and combined with multivariate statistical process monitoring method to enhance fault detection efficiency. Under framework of PCANet, state space model was added to network structure as dynamic layer to solve dynamic issue of industrial process data. In addition, the output layer was redesigned to use fault detection as target function. Finally, method feasibility and validity for fault detection were verified by simulated testing on the Tennessee Eastman (TE) process.

    Corrosion failure mechanism of return pipeline elbow of regeneration tower in LPG desulfurization unit
    ZHANG Jianwen, SU Guoqing, JIANG Aiguo
    2018, 69(8):  3537-3547.  doi:10.11949/j.issn.0438-1157.20180165
    Abstract ( 88 )   PDF (4286KB) ( 64 )  
    References | Related Articles | Metrics

    Elbow mainly controls medium flow direction in pipelines, and is one of the most commonly used pipeline components in oil and gas transportation. Corrosion-induced failure was studied on return pipeline elbow of regeneration tower in LPG desulfurization unit. From both macroscopic and microscopic viewpoint, distribution of corrosion pore diameters and reduction of wall thickness of failed elbow were surveyed. Physicochemical analysis was further performed by X-ray diffraction (XRD)and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The results show that corrosion is gradually intensified along fluid flow direction and a complete destruction zone is formed in the middle and outlet of the elbow. The main mechanism of elbow corrosion failure was that fluid scour destroyed protective film formed by electrochemical corrosion and weakened its protective effect on substrate, resulting in continuous corrosion of inner wall. Also, the presence of heat-stable salts aggravated elbow corrosion.

    Effects of different accelerated tests on failure process of epoxy/polyurethane coating
    HU Mingtao, JU Pengfei, ZHAO Xuhui, TANG Yuming, ZUO Yu
    2018, 69(8):  3548-3556.  doi:10.11949/j.issn.0438-1157.20180256
    Abstract ( 104 )   PDF (1261KB) ( 59 )  
    References | Related Articles | Metrics

    Failure process of epoxy zinc yellow primer/acrylic polyurethane coating system on aluminum alloy substrate was studied under simulated ocean atmosphere environment. By comparative evaluation at cyclic acceleration, UV/condensation and neutral salt spray conditions, effects on failure modes of epoxy primer, polyurethane topcoat and composite coating were assessed. Results showed that UV/condensation had strong destructive effect on acrylic polyurethane topcoat, but had little effect on impedance change of overall composite coating. During UV/condensation process, experimental temperature within glass transition temperature of topcoat and UV damage on carbamate group were main reasons for topcoat destruction. Salt spray had minimal effect on change of gloss loss and color difference, whereas consistent salt spray infiltration obviously accelerated impedance decrease of the coating system and caused significant reduction of adhesion between primer and substrate. Compared to UV/condensation or salt spray test alone, cyclic accelerated tests considered influences of different environmental factors such as strong solar radiation, high temperature and humidity, high salinity and temperature difference in ocean atmosphere of the South Sea, which can more accurately reflect failure process of the coating system in the region.

    Characterization of rubber O-ring seal in high-pressure gaseous hydrogen
    ZHOU Chilou, CHEN Guohua
    2018, 69(8):  3557-3564.  doi:10.11949/j.issn.0438-1157.20171691
    Abstract ( 155 )   PDF (1162KB) ( 92 )  
    References | Related Articles | Metrics

    Rubber O-ring seal in high-pressure hydrogen system swells due to hydrogen absorption and dissolution after direct exposure to high pressure and high purity gaseous hydrogen. Few works are available in literature on swelling effect on seal performance. A constitutive model of rubber hyperelasticity coupled with hydrogen-induced strain was proposed. Finite element software ABAQUS and user material subroutine (UMAT) program were used to establish a finite element analysis model of hydrogen-swelled rubber O-ring seal in high-pressure hydrogen. Effect of swelling on O-ring seal performance was further studied with the developed model. Results showed that seal contact stress was increased by swelling, which is beneficial to maintain seal performance. However, hydrogen swell increased height and area of O-ring cross section and Mises stress of O-ring, which may make it more susceptible to crack and less reliable of seal quality. Therefore, design pre-compression ratio and groove of rubber O-ring seal structure in high-pressure hydrogen shall consider hydrogen swelling influence in order to avoid occurrence of high stress and O-ring extrusion.

    Performance analysis of double-end self-pumping mechanical seal for main coolant pump of sodium-cooled fast reactor
    CHEN Guoqi, SUN Jianjun, SUN Dianfeng, MA Chenbo
    2018, 69(8):  3565-3576.  doi:10.11949/j.issn.0438-1157.20180101
    Abstract ( 70 )   PDF (630KB) ( 64 )  
    References | Related Articles | Metrics

    Sealing performance of reactor coolant pump is an important indicator for safety evaluation of sodium-cooled fast reactor. A double-end self-pumping mechanical seal was proposed for certain type of coolant pump for sodium-cooled fast reactor. Fluent numerical simulation at conditions of orthogonal design of experiments was performed to study influence of structural and operational parameters on open force and leakage rate of end surface. The pressure adjustment range of blocking fluid was analyzed to meet the requirement of zero argon leakage in the pump chamber. The results show that although both affect the open force within the experimental range of these parameters, the influence of ratio of groove to face width is more significant than that of helix angle. The open force was increased with the increase of ratio of groove over face width and helix angle. Also, the ratio of groove to face width had a significant effect on the leakage rate, which was increased rapidly with the increase of the ratio of groove to face width. The relationship between pressure of blocking fluid with both leakage rate and open force was obtained for conditions of maximum speed and shutdown. The mechanical seal is assured to be safe and effective at 0.05 MPa pump working pressure as long as blocking fluid pressure is controlled within 0.0528-1.6378 MPa.

    Bioactive coating prepared by bio-3D printing of castor oil-based waterborne polyurethane mixed with carbonic anhydrase
    CUI Jiandong, CUI Zhaohui, SU Zhiguo, ZHENG Chunyang, MA Guanghui, ZHANG Songping
    2018, 69(8):  3577-3584.  doi:10.11949/j.issn.0438-1157.20180054
    Abstract ( 117 )   PDF (1495KB) ( 92 )  
    References | Related Articles | Metrics

    Castor oil-based anionic waterborne polyurethane (WPU) mixed with carbonic anhydrase (CA) was used to prepare bioactive coatings by bio-3D printing technique and regular coating methods. Interactions between CA and WPU were studied by dynamic light scattering, IR, SEM-EDC, TGA, and contact angle analyses. The results showed that the CA could attach tightly to WPU nanoparticles through the electrostatic interactions with anionic groups on the polyurethane. The activity recovery of bioactive coatings prepared by bio-3D printing technology was 4-fold higher than that of the conventional coating method, reaching 50.51%. The higher activity recovery could be attributed to the thin layer, smooth surface, and uniform distribution of CA in the 3D printed coating.

    Reentrant aggregation and fractal structure of bovine serum albumin pre-aggregates in dispersion induced by multivalent counterions
    WEI Dan, JIANG Gan, SU Qiulan, XIA Zhengbin
    2018, 69(8):  3585-3595.  doi:10.11949/j.issn.0438-1157.20180288
    Abstract ( 44 )   PDF (1255KB) ( 41 )  
    References | Related Articles | Metrics

    Bovine serum albumin pre-aggregates in dispersion undergo a reentrant aggregation phenomenon upon adding trivalent counterion Y3+ found by dynamic light scattering experiment, i.e. the aggregation of BSA-PAs is very slow at low counterion concentration, and it increases as the counterion concentration increases, while aggregation decreases as counterion concentration further increases. This reentrant condensation phenomenon is attributed to the short-ranged repulsive hydration force originating from increased dipoles generated by excess multivalent counterion binding. Small-angle light scattering and TEM (transmission electron microscope) results indicate that the incompact filamentous aggregates are formed at low and high counterion concentration, and the compact globular aggregates are formed at intermediated counterion concentration, which further supports the exist of hydration force at high counterion concentration. Hydration force occurs mainly on charged or polar patches of protein to protect it from aggregating; the aggregation of the filamentous BSA-PAs at hydrophobic patches at the two ends is still possible.

    TBCFB system simulation and optimization for pyrolysis-gasification-combustion of low rank coal
    WANG Yaxiong, YANG Jingxuan, ZHANG Zhonglin, MA Xuli, LI Peng, HAO Xiaogang, GUAN Guoqing
    2018, 69(8):  3596-3604.  doi:10.11949/j.issn.0438-1157.20180280
    Abstract ( 217 )   PDF (633KB) ( 210 )  
    References | Related Articles | Metrics

    The quality-based utilization technology of low rank coal has attracted much attention due to its advantages in energy saving and emission reduction. A novel triple-bed combined circulating fluidized bed (TBCFB) system, which includes a pyrolyzer, a gasifier and a combustor, is developed to minimize energy loss. A new process was proposed to used char coal particles instead of sand particles as heat-carried circulating medium and an Aspen Plus process simulation was established to obtain optimum operating conditions for material conversion and energy utilization between three bed reactors. The results showed that 40% char coal combustion could provide enough energy for both low rank coal pyrolysis at 600℃ and gasification of water over 60% residual char coal at 800.9℃. High heat capacity char coal particles significantly reduced amount of heat-carried particles needed to circulate in the system. To meet the requirements of heat transportation, mass ratio of char coal to low rank coal was 5.5, whereas mass ratio of quartz and ash to low rank coal were 11 and 12, respectively. Comprehensive analysis of syngas composition, cold gasification efficiency (CGE) and lower heating value (LHV) indicated optimal ratio of steam to char coal (St/C) was 1.5 in gasification. The simulation results would provide some guidance on industrial application of TBCFB system with char coal as heat-carried particles.

    Relationship between liquid change in dual chambers and performance of electricity production in DCMFC
    YIN Yue, YUAN Linjiang, NIU Yuwei
    2018, 69(8):  3605-3610.  doi:10.11949/j.issn.0438-1157.20180159
    Abstract ( 90 )   PDF (457KB) ( 85 )  
    References | Related Articles | Metrics

    The liquid level difference between the cathode and the anode increased obviously with increase of operation cycles in the dual chamber microbial fuel cell (DCMFC). To analyze this phenomenon, the transport behavior of proton and water was investigated from evaporation, osmotic pressure, metabolism and electric field. The relationship between water production and the fuel's performance was studied. The results showed that within 360 h, the liquid change due to evaporation and osmotic pressure was less than 0.50 ml (liquid level declined near 0.5 mm). Within 312 h of circuit breakage, the anodic metabolism gas led to the proton exchange membrane (PEM) deformation convex to the cathode. The anodic liquid decreased 6.20 ml (liquid level reduced near 6.5 mm), the cathodic liquid increased 10.75 ml (liquid level rose near 11.2 mm) and the liquid level difference reached 17.7 mm. Under the circuit connection, except the PEM deformation, the protons were dragged by electro-osmotic to the cathode and reduced to water. Within 312 h, the anodic liquid decreased 10.70 ml (liquid level reduced about 11.1 mm), the cathodic liquid increased 17.00 ml (liquid level rose about 17.7 mm), and then formed a 28.8 mm liquid level difference. Moreover, the water transmission increased with the increase of output voltage. The results implied that the biological metabolism and electro-osmotic had an important influence on DCMFC liquid difference. It was possible to calculate proton transfer rate based on its water production. The proton transfer rate in the system was over 54%. This study provided a simple and intuitive basis for judging the electricity production efficiency.

    Co-combustion characteristics and kinetic analysis of semi-coke and bituminous coal
    ZHANG Jinping, WANG Chang'an, JIA Xiaowei, WANG Pengqian, CHE Defu
    2018, 69(8):  3611-3618.  doi:10.11949/j.issn.0438-1157.20180211
    Abstract ( 114 )   PDF (494KB) ( 80 )  
    References | Related Articles | Metrics

    Co-combustion of bituminous coal with low volatile semi-coke is an effective method, which can improve the ignition and burnout performance of semi-coke. This paper describes the combustion characteristics differences, interaction effect, kinetic analysis of semi-coke and anthracite blended with bituminous coal by applying thermogravimetric analyzer. The results indicate that the combustion process of semi-coke is divided into two stages:combustion of combustible materials, and decomposition of calcium carbonate in the semi-coke. The main mass loss peak of the blend fuels close to DTG peak of the single fuel, which has an approximate fuel ratio with the blend. The blend of semi-coke with bituminous coal has better ignition and comprehensive combustion characteristics than blend of anthracite with bituminous coal. Addition of bituminous coal can lower the apparent activation energy, and improve the ignition and burnout performance of semi-coke or anthracite. Moreover, the apparent activation energy decreased, while the ignition and comprehensive combustion characteristics index increased with the blend ratio of bituminous coal. There exist more significant synergetic effects between bituminous coal and semi-coke than between bituminous coal and anthracite. In addition, the ignition index and comprehensive combustion index reveals negative correlation with fuel ratio, while the apparent activation energy shows positive correlation with fuel ratio.

    Experimental study on U(Ⅵ) bioreduction by incubated sulfate reducing bacteria sediment in groundwater
    LI Dianxin, HU Nan, HUANG Chao, DING Dexin, LI Guangyue, WANG Yongdong
    2018, 69(8):  3619-3625.  doi:10.11949/j.issn.0438-1157.20180219
    Abstract ( 84 )   PDF (753KB) ( 70 )  
    References | Related Articles | Metrics

    To study how the incubated sulfate reducing bacteria (SRB) sediment affects U(Ⅵ) bioreduction, the sediment together with ethanol was added into the sediment-groundwater microcosms, which were compared with microcosms amended with both pure SRB and ethanol and with ethanol only. The results indicated that uranium concentrations of the microcosms amended with the incubated SRB sediment together with ethanol, the pure SRB together with ethanol, and ethanol decreased below 0.05 mg·L-1 (GB 23727-2009) at day 19, 22 and 28, respectively. The diversity of microbial communities capable of reducing U(Ⅵ) in all the microcosms had no significant difference. The abundances of microbial communities capable of reducing U(Ⅵ) in the microcosms amended with the incubated SRB sediment together with ethanol, and the pure SRB together with ethanol, in which ethanol were 35.3%, 32.5% and 13.1%, respectively. The abundance of microbial communities capable of reducing U(Ⅵ) increased when the incubated SRB sediment together with ethanol was added into the sediment-groundwater microcosm. It is indicated that incubated SRB sediment could accelerate the bioreduction of U(Ⅵ) in the microcosm.

    Effect of additional carbon sources on nitrogen and phosphorus removal characteristics in A2/O-BCO process
    SUN Yawen, ZHANG Jianhua, PENG Yongzhen, WANG Shuying
    2018, 69(8):  3626-3634.  doi:10.11949/j.issn.0438-1157.20180139
    Abstract ( 100 )   PDF (651KB) ( 95 )  
    References | Related Articles | Metrics

    Simultaneous nitrogen and phosphorus removal could be realized by denitrifying phosphorus removal system. However, a shortage of organic carbon for wastewaters with low COD/N ratio can result in adding carbon source to overcome the limitation of low organic carbon. By adding carbon sources to adjust influent COD/N ratio around 4.3,the role of various carbon source in the A2/O-BCO(anaerobic anoxic oxic-biological contact oxidation)process was investigated. The batch tests were used to further research the substrate storage and conversion of activated sludge with various additional carbon sources. These results showed that the substrate storage and utilization characteristics were influenced by the type of influent carbon, which further effected the nitrogen and phosphorus removals. When sodium propionate was the additional carbon source, PO43--P removal steadily maintained around 94%, however, the removal efficiency of TIN was 70.82%. For sodium acetate, TIN removal reached to 74%, but the average removal efficiency of PO43--P was 89.90%. The conversion analysis of carbon source revealed that the content of PHA was mainly PHV with adding sodium propionate in the anaerobic phase. On the contrary, the proportion of PHB increased with adding sodium acetate. In the anoxic phase, the effect of PHB and PHV degradation by DPAOs was closely related to its content. Compared to PHB, PHV is liable to be absorbed by DPAOs. When sodium propionate was used as additional carbon source, the higher PHV degradation rate and productivity efficiency were observed, which improved the phosphorus absorption rate. In addition, the optimal operation strategy of the A2/O-BCO process with various sources was proposed.

    Partial nitrification coupled anaerobic ammonia oxidation process to treat low C/N domestic sewage
    YANG Qing, YANG Yubing, LI Jianmin, FENG Hongli, ZHOU Xueyang, LIU Xiuhong
    2018, 69(8):  3635-3642.  doi:10.11949/j.issn.0438-1157.20180107
    Abstract ( 109 )   PDF (665KB) ( 237 )  
    References | Related Articles | Metrics

    To achieve high-efficiency and low-consumption stable removal of municipal wastewater, the start-up and nitrogen removal performance of partial nitration-anaerobic ammonium oxidation(Anammox) process were studied under normal temperature conditions. The results showed that real-time control strategy can quickly start partial nitrification under high DO (2.5 mg·L-1) conditions. The unique structure of biofilm provides Anammox bacteria with good anaerobic environment in the presence of dissolved oxygen. Overcame temperature changes during start-up. After 173 d, the removal rate of ammonia nitrogen and nitrite reaches more than 90%, the removal rate of total nitrogen (TN) approach to 80%. Anammox filter started successfully after 173 d. The nitrogen removal performance of the coupled system under different filtration conditions was studied. The results showed that the total nitrogen volumetric loading of the coupled system reached 0.75 kg·m-3·d-1 when the filtration rate was 0.5 m·h-1. The average concentration of TN in the effluent was 8 mg·L-1. The nitrogen of municipal wastewater could be treated stably and efficiently through partial nitrification-anaerobic ammonia oxidation process.

    Study on chemical kinetics of Na2SO4 formation in coal fired flue gas
    ZHANG Zhichao, LIU Jing, YANG Yingju, ZHANG Zhen
    2018, 69(8):  3643-3650.  doi:10.11949/j.issn.0438-1157.20180051
    Abstract ( 107 )   PDF (564KB) ( 139 )  
    References | Related Articles | Metrics

    The formation of gaseous sodium sulphate during Zhundong coal combustion leads to a series of problems such as the deposition and corrosion of heat exchange surface and the deactivation of tail SCR catalyst. Therefore, the kinetic study on the transformation of Na2SO4 is important for predicting and controlling the Na2SO4 formation in coal-fired flue gas. In this study, a more complicated chemical kinetic model of Na/Cl/S/O/H in flue gas was established and the formation mechanism of Na2SO4 was studied. The influence of oxygen content, temperature, SO2and H2O concentrations on Na2SO4 formation was also investigated. The model predictions were in good agreement with the experimental results. Oxygen promoted the formation of Na2SO4. Even though the chemical reactions were accelerated at high temperature, the Na2SO4 formation was inhibited. The effects of SO2 and H2O on Na2SO4 formation depended on reaction temperature. The path analysis indicated that there were two important paths to form Na2SO4:(1) the direct oxidation of SO2 (NaCl→NaSO3Cl→NaHSO4→Na2SO4), and (2) the indirect oxidation of SO2(NaCl→NaO2→NaSO4→NaHSO4→Na2SO4). The result of sensitivity analysis showed that the Na2SO4 formation was sensitive to the reactions that generated or consumed radicals in the system.

    Synergistic effect of silicon-aluminum addition and seed-induced on stabilization of heavy metals in MSW incineration fly ash during hydrothermal process
    SHI Dezhi, WANG Pan, HU Chunyan, LI Pengfei, ZHANG Chao, WEI Yunmei, GU Li
    2018, 69(8):  3651-3661.  doi:10.11949/j.issn.0438-1157.20180046
    Abstract ( 127 )   PDF (857KB) ( 154 )  
    References | Related Articles | Metrics

    Coal fly ash (CFA), bentonite, kaolin and diatomite were selected as silicon-aluminium additives and tobermorite crystal were synthesized as seed added. Synergistic effect of silicon-aluminium addition and seed-induced on stabilization of heavy metals including Pb, Zn, Cu, Cd, and Cr in municipal solid waste (MSW) incineration fly ash (FA) during hydrothermal process under 150℃ was studied. Zeolites could not be formed by hydrothermal treatment (HT) mainly due to the high content of Ca but low content of Si, Al in FA, which led to the leaching toxicity of Pb (5.45 mg·L-1) beyond the limited value of non-hazardous waste. Hibschite or katoite were found in HT products with 10% mass of additives solely or combined added. Tobermorite could be successfully synthesized with higher 30% mass of additives solely or combined added, which was attributed to the proper element of Ca/(Al+Si) adjusted near 0.67-1.20. Leaching toxicity of Pb in HT products decreased to 0.30 mg·L-1 with 30% mass of combined additives including CFA and diatomite(1:1), and it decreased to lowest level (0.28 mg·L-1) with more 3% mass of seed added which owing to the effective synthesis of tobermorite from first 6 h. Furthermore, seed-induced hydrothermal treatment of FA with combined silicon-aluminium additives could cause the inhibition of heavy metals migration into liquid during hydrothermal process. The decrease of heavy metals in liquid phase, and the decrease of leaching toxicity of heavy metals in solid phase (HT products) were observed, which indicated that heavy metals were really stabled in solid phase.

    Study on release of polycyclic aromatic hydrocarbons during sewage sludge pyrolysis
    HU Yanjun, YU Fan, CHEN Jiang, YU Wenjing, LU Yanjun
    2018, 69(8):  3662-3669.  doi:10.11949/j.issn.0438-1157.20180018
    Abstract ( 108 )   PDF (673KB) ( 110 )  
    References | Related Articles | Metrics

    The production and distribution of 16 kinds of polycyclic aromatic hydrocarbons (PAHs) in liquid, gas and solid three-phase products from sewage sludge pyrolysis from 350 to 1050℃ were studied. The results show that PAHs tend to be concentrated in liquid product, then into gaseous and solid products. The mass ratio of 16 kinds of PAHs contained in liquid product reaches the highest value 96% at 650℃. 16 kinds of EPA-PAHs in liquid products are all detected out. The mass ratio of ∑16PAHs in gas phase products at 750℃ reaches the highest value, 21.3%. The content of PAHs in solid product is very low, which is 1%. At all the targeted pyrolysis temperatures, 2, 3 and 4 rings of PAHs occupied a leading position in the resulting products. The mass ratio of ∑2,3,4 rings of PAHs was over 95%, and the highest content of EPA-PAHs in liquid phase products is 15.25 mg·kg-1 at 850℃. In the gas phase, it mainly contains naphthalene (NaP), acenaphthylene (Acp), fluorene (Flu) and anthracene (Ant), and the high ring of PAHs are not detected out. During a high temperature sludge pyrolysis, the thermos-chemical reaction of large molecular structure reaches a peak, along with the functional-groups decomposition, synthesis, and cyclization reactions, the concentration of ∑low PAHs in gas product reached 7.248 mg·kg-1. The variation of PAHs TEQ in the pyrolysis products from different temperatures basically agrees their concentration distributions. The TEQ of PAHs in the liquid product is up to 1.129 at 850℃.

    Dielectric properties of mixed materials in transesterification reaction system
    SONG Rui, JIN Guangyuan, CUI Zhengwei, SONG Chunfang, CHEN Haiying
    2018, 69(8):  3670-3677.  doi:10.11949/j.issn.0438-1157.20180105
    Abstract ( 74 )   PDF (571KB) ( 75 )  
    References | Related Articles | Metrics

    In recent years, microwave enhanced chemical reaction has been widely used in the chemistry technology of biodiesel. There are some limitations in the study of microwave technology in chemical engineering applications. The dielectric properties of materials are one of the most important factors. Based on the transesterification reaction system of methanol and rapeseed oil with self-made catalyst, the dielectric constant of methanol and rapeseed oil transesterification system under different reaction conditions was measured by vector network analyser. The effects of reaction temperature, molar ratio of methanol to oil and the dielectric properties of the catalyst, were discussed based on experimental results. Combined with the kinetics of transesterification reaction, the influence of reaction temperature on the dielectric properties was discussed to provide material dielectric information for multi-physics simulation of transesterification under microwave heating.

    Study of simultaneous separation of lignosulfonate and xylooligosaccharides from magnesium bisulfite pretreated wheat straw spent liquor
    LIU Lei, REN Jiwei, LIU Xinlu, ZHENG Zhaojuan, LI Xin, OUYANG Jia
    2018, 69(8):  3678-3685.  doi:10.11949/j.issn.0438-1157.20180064
    Abstract ( 77 )   PDF (581KB) ( 55 )  
    References | Related Articles | Metrics

    Using solvent extraction, ultrafiltration, macroporous resin adsorption, and ion exchange methods, lignosulfonate and xylooligosaccharides were separated from magnesium bisulfite pretreated wheat straw spent liquor. The results showed that the ultrafiltration cannot achieve the purpose of separation. The magnesium lignosulfonate can be purified by organic solvent extraction and macroporous resin adsorption. D380 ion exchange resin was selected to completely separate xylooligosaccharides and lignosulfonate by ion exchange fixed bed simultaneously, the purity of recovered xylooligosaccharides and lignosulfonate could reach 63.95% and 91.28% respectively. Thus, ion-exchange fixed bed packed with D380 is an effective and simple way to recover high-valued chemicals from spent liquor, which achieved complete utilization of magnesium bisulfite pretreated wheat straw spent liquor with robust market prospects.

    Effect of ionic liquid micro emulsion pretreatment on rice straw at ultra-high pressure
    GAO Jing, ZHENG Caiju, TAN Tingru, ZHANG Di, LIU Shucheng, JI Hongwu
    2018, 69(8):  3686-3692.  doi:10.11949/j.issn.0438-1157.20171550
    Abstract ( 75 )   PDF (630KB) ( 46 )  
    References | Related Articles | Metrics

    Rice straw was pretreated by ultra-high pressure (UHP), ionic liquid micro emulsion (ILM), and ILM in UHP environment (ILM+UHP) at mild temperatures. The effect of the pretreatments on the chemical composition, crystalline structure, surface morphology and enzymatic hydrolysis of rice straw were investigated. The results show that after the pretreatment with 1-ethyl-3-methylimidazolium acetate/cyclohexane/Triton X-100/n-butanol ILM at 500 MPa, 50℃, for 4 h, 61.5% of the lignin was removed, crystallinity index was reduced by 17.3%, the surface was coarse and porous, and the reducing sugar yield achieved 75.3%.

    Chlorine release during low-temperature pyrolysis of olive residue
    XIE Min, CHENG Jian, CHEN Gang, ZHANG Lei, REN Xiaohan
    2018, 69(8):  3693-3700.  doi:10.11949/j.issn.0438-1157.20180176
    Abstract ( 100 )   PDF (564KB) ( 59 )  
    References | Related Articles | Metrics

    Biomass direct combustion is the main way of biomass energy utilization. Chlorine plays an important role in boiler slagging and corrosion during the combustion of high-chlorine biomass. Low-temperature pyrolysis could make chlorine release and get the low chlorine content biomass. We assessed the effect of the low-temperature pyrolysis intensity on the chlorine content of residual biomass and of the released gaseous species. For this purpose, olive residue was subjected to low-temperature pyrolysis (mild pyrolysis) at furnace temperatures, in the range of 250-400℃ in an inert nitrogen atmosphere. The major chlorinated species in the evolving pyrolysis gas (torgas) were identified as HCl and CH3Cl, and quantified. HCl and CH3Cl will compete Cl which is released during biomass low-temperature pyrolysis and low temperature will promote the conversion of Cl to CH3Cl. When the temperature is below 350℃, CH3Cl is the main product of Cl release and when the temperature arrives at 400℃, HCl will replace CH3Cl to become the main product during low-temperature pyrolysis.

    Thermal enhanced air sparging for oil contamination remediation in shallow groundwater of cold regions
    CHU Tong, YANG Yuesuo, LU Ying, WU Yuhui, CHEN Yu, DU Xinqiang
    2018, 69(8):  3701-3710.  doi:10.11949/j.issn.0438-1157.20180265
    Abstract ( 88 )   PDF (816KB) ( 53 )  
    References | Related Articles | Metrics

    Air sparging(AS) is often used to treat organic pollution in groundwater and soil, while the remediation efficiency would be restricted by complex field conditions such as low temperature in cold regions. Based on the results of AS pilot test in the field, taking toluene as a representative pollutant, the remediation effect of thermal enhanced air sparging for the field scale was predicted and evaluated by indoor soil column experiment and numerical modelling. The results show that there is a direct proportional relationship between the volatilization rate of toluene and temperature. In the soil column experiments, the toluene concentration decay faster under the condition of AS with high temperature gas injection. Numerical simulation of thermal enhanced air sparging for field site shows that the conduction radius of temperature is 2-4 m and the influence scope of the pollutants could expand to the area within a 10 m radius, which is about 40%-50% larger than normal AS in winter.

    Preparation and characterization of AgO ordered array electrode materials
    TIAN Hua, ZHANG Zhiying, LIU Chunyan
    2018, 69(8):  3711-3716.  doi:10.11949/j.issn.0438-1157.20180190
    Abstract ( 84 )   PDF (1037KB) ( 63 )  
    References | Related Articles | Metrics

    AgO ordered array materials were synthesized by electrochemical oxidization of Ag naoparticles in sodium hydroxide solution. As the characterizations of properties revealed, the prepared AgO material has unique straight-through hollow structure, bringing a positive effect on the dispersion of electrolyte inside materials, which would result in better electrochemical properties of corresponding batteries. Thus prepared AgO material could be used as an electrode directly without any binders. The electrode offered a discharge capacity of 422.6 mA·h·g-1 at 3 C rate and utilization ratio of electrode material could reach 97.8% as a cathode of Al/AgO battery (stopping potential is 0.5 V and reference electrode is Ag/Ag+ electrode). There was still a capacity of 387.8 mA·h·g-1 at 7 C rate with utilization ratio 89.7%. Meanwhile, the cycling performance was also improved and a specific capacity of 405.2 mA·h·g-1 could still be offered at the 10th cycle. The work provides a facile and eco-friendly method and the prepared AgO materials would have unique advantages in practical applications.

    Crystal structures, electronic structures and conductivity of Si highly doped RuO2
    LI Guorong, ZOU Xiangda, WANG Qifan, WANG Xin, TANG Zhongzhi, ZHOU Yangjie, TANG Dian
    2018, 69(8):  3717-3723.  doi:10.11949/j.issn.0438-1157.20180070
    Abstract ( 111 )   PDF (617KB) ( 65 )  
    References | Related Articles | Metrics

    The first-principle method based on the density functional theory(DFT) was performed to investigate the crystal structural characteristics of highly Si-doped (Ru1-xSix)O2 (x=0,0.125,0.25,0.375 and 0.5). The phase analysis of Si-doped RuO2 evidently proves that the high concentrated Si solid solutions are achieved by thermal decomposition with proper annealing process. The band structures show that the highly Si-doped RuO2 always maintains metallic nature. The density of states suggests that the electrical conductive-hosts originate from Ru-4d and O-2p electrons, along with small amount Si-3p electrons. The descending of electrical conductivity of Si-doped (Ru1-xSix)O2 abides by the single exponential attenuation trend with increasing Si doping.

    Preparation of ZIF-8 membranes on ZnO modified stainless steel nets
    LI Jia, GU Jinghua, YIN Wenjie, LI Zeyao
    2018, 69(8):  3724-3731.  doi:10.11949/j.issn.0438-1157.20180194
    Abstract ( 67 )   PDF (1436KB) ( 57 )  
    References | Related Articles | Metrics

    ZIF-8 is one of the most perspective membrane materials for gas separation due to its regular pore size of 0.34 nm. Stainless steel nets (SSN) have the advantages of low price, easy cutting, and thin thickness as membrane substrates. In this work, ZnO buffering layer was synthesized on SSN substrate by hydrothermal method. ZIF-8 membranes were prepared on the ZnO modified SSN (ZnO/SSN) supports. ZnO/SSN supported ZIF-8 membranes were characterized by X ray diffraction (XRD) and scanning electron microscopy (SEM). The gas separation property of prepared ZIF-8 membranes was carried out. It is indicated that phase-pure and defect-free ZIF-8 membrane can be obtained on the ZnO/SSN substrate without additional activation step of ZnO layer. The ideal separation factors of H2/CO2, H2/N2 and H2/CH4 were 7.3, 9.2 and 12.4 at room temperature. The membrane demonstrates a good stability of permeability at 150℃.

    Microstructural characterization and properties of Zn(O,S) thin film prepared by CBD method
    HUANGFU Lijuan, JIANG Yaxiao, ZHANG Sen, XU Tingting, XU Junmin, WANG Xinchang, CHEN Yongsheng
    2018, 69(8):  3732-3739.  doi:10.11949/j.issn.0438-1157.20180237
    Abstract ( 89 )   PDF (1126KB) ( 61 )  
    References | Related Articles | Metrics

    Zn(O,S) thin film has been successfully used in Cu(In,Ga)Se2 based solar cells. However, its application in perovskite solar cell has not been reported. In this paper, Zn(O,S) film prepared by low temperature chemical bath deposition has been studied. The morphology, structure and composition of the film were characterized by XPS,SEM,XRD, Raman spectra, PL spectra and UV-Visible absorption spectra. The band structure of the thin film is analyzed by UPS. The possibility of Zn(O,S) film being the electron transport layer of the perovskite solar cell is explored. The research shows that the Zn(O,S) thin film deposited by CBD belongs to the mixed membrane. The composition of the phase consists of ZnO, ZnS and ZnOS alloys. The prepared Zn(O,S) film has the equivalent electronic extraction capability to the CH3NH3PbI3 optical absorption layer with TiO2. It is a kind of high efficient flexible perovskite battery electronic transport layer material.

    Quantitative description of oxygen inhibition in radical UV-curing
    ZHU Guojian, FAN Tianfeng, WANG Dehai, BAO Liubing
    2018, 69(8):  3740-3746.  doi:10.11949/j.issn.0438-1157.20180155
    Abstract ( 87 )   PDF (547KB) ( 110 )  
    References | Related Articles | Metrics

    Curing rate curve was multimodally fitted by the peak separation method based on the consideration that free radical UV-curing process is generally caused by multiple active centers. A parameter of tV-inh, which is the intersection of abscissa and the tangent line of the inflection point of curing rate curve, is assigned to evaluate oxygen inhibition extent. The results showed a more oxygen-sensitive curing reaction could be isolated by overlapping peak resolving, and the relationship between tV-inh and initiator content x turned out to be fulfilled the algebraic expression of tV-inh=A/x+B optimally, and the value of (A+B) could be used to describe the oxygen inhibition trend for a given curing formula.

    Heat release rate model of regular burning polystyrene sheet
    CHEN Peiran, LI Haihang, DING Jie, LIN Peng
    2018, 69(8):  3747-3753.  doi:10.11949/j.issn.0438-1157.20171446
    Abstract ( 92 )   PDF (583KB) ( 88 )  
    References | Related Articles | Metrics

    Combustion experiments of polystyrene (PS) sheet in multiple dimensions were carried out on a small scale ISO 9705 cone calorimeter, which took 10cm×10cm plate as one unit and measured value of heat release rate. The flame began to accelerate spreading from the ignition corner to unburned region at the same speed upon ignition at right corner of PS sheet, and diffused in a geometry of regular fan. According to the shape of heat release rate (HRR) curve, combustion process was divided into three stages:ascending, plateau and declining stages. By analysis of heat release rate and combustion process, a linear relationship was found between total heat release and material area. Heat release in the ascending stage was about 77.83% of total heat release for burnings without a plateau. HRR curves were fitted with exponential function by combustion thermophysical parameters, such as heat release peak rate, peak time and heat release amount. The fitting results showed similar parameters which a mean of ascending stage was 0.003888 and mean of declining stage was -0.01178. Unified mathematical equation was obtained for ascending stage by taking 10×10-1 peak time of an experimental group as reference time. Both non-plateau peak value and peak time was calculated from correlation of heat release at ascending stage and total heat release. Further experiments verified that the mathematic model can predict heat release rate development of regular burning polystyrene sheet with and without plateau stage.

    Factors affecting the minimum burning pressure of ammonium nitrate
    WANG Xu, XU Sen, TIAN Yaokai, LIU Dabin
    2018, 69(8):  3754-3762.  doi:10.11949/j.issn.0438-1157.20180023
    Abstract ( 117 )   PDF (720KB) ( 90 )  
    References | Related Articles | Metrics

    Ammonium nitrate based explosives do not undergo self-sustained combustion when the pressure is lower than some threshold value, which is called the minimum burning pressure (MBP). The MBP has become a significant parameter in the production and management of ammonium nitrate based explosives. In order to study the effect of oil content on the safety of ammonium nitrate, the MBP values of samples were measured by pressurized vessel test. At room temperature, samples with 0 to 10% oil content were measured, and the MBP values of the samples were reduced from 6 MPa to 1.59 MPa. Samples with 4%, 6%, 8% and 10% oil content were measured at 20℃, 75℃ and 100℃, and the MBP values of the samples decreased from 2.25, 2.01, 1.75 and 1.59 MPa to 1.51, 1.05, 0.41 and 0.21 MPa, respectively. The results showed that the MBP values decreased with the increase of oil content at normal temperature. In addition, the MBP values of the ammonium nitrate mixed with oil decreased obviously when the initial temperature was increased.