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Table of Content
05 July 2015, Volume 66 Issue 7
    CIESC Journal(HUAGONG XUEBAO)Vol.66 No.7 May 2015
    2015, 66(7):  0-0. 
    Abstract ( 153 )   PDF (1381KB) ( 281 )  
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    Preliminary inquiry of monitored natural attenuation remediation of chlorinated organic compounds contaminated sites
    CHEN Ranran, ZHU Xin, LIN Yusuo, YU Ran, LONG Tao
    2015, 66(7):  2361-2369.  doi:10.11949/j.issn.0438-1157.20150003
    Abstract ( 298 )   PDF (553KB) ( 655 )  
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    Due to the high toxicity, potential of biological accumulation, recalcitrance to degradation and the known carcinogenic/teratogenic/mutagenic effects, the chlorinated organic compounds have been listed as priority controlled pollutants by the United States Environmental Protection Agency (EPA). In view of chlorinated pollutants contaminated sites, the traditional physical, chemical and biological remediation methods often impose relatively high costs and considerable impacts on the surrounding environment. The monitored natural attenuation (MNA) is an effective technology for site remediation and management and has been widely used internationally, which gradually attracts more and more attentions in China in recent years. It relies on the intrinsic potential of the pollutants to degrade naturally to meet the remediation requirements, and thereby would reduce treatment costs and lower on-site project risks. This paper focuses on the introduction of MNA technology, as well as the characteristics of chlorinated organic compounds such as the biodegradation pathways and mechanisms during the process of natural attenuation, the main degradation microbial communities and the key biodegradation enzymes. A preliminary discussion on the suitability of implementing MNA remediation on chlorinated organic compounds contaminated sites is provided.

    Embedding microbial fuel cell into constructed wetland systems for electricity production and wastewater treatment: state-of-the-art
    XU Dan, XIAO Enrong, XU Dong, WU Zhenbin
    2015, 66(7):  2370-2376.  doi:10.11949/j.issn.0438-1157.20141397
    Abstract ( 250 )   PDF (542KB) ( 1066 )  
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    Constructed wetland-microbial fuel cell (CW-MFC) is a newly emerging device in which electricity can be generated by microorganisms that use wastewater and root exudates as fuel. The novelty of this system is enhanced purifying effect of treating wastewater and simultaneously electricity generation by embedding MFC into CW. The effectiveness of the system depends on the configuration of reactor, the operational and environmental parameters. Identification and optimization of these parameters are important to enhance the efficiency of the hybrid system. In this review following the introduction and explanation of the principle, the development process and the present situation of CW-MFC systems, the factors influencing the performance of the systems were described focusing on the major components including plants, microorganisms, electrodes and separators, and the impact of important variables involving carbon source, oxidation reduction potential and hydraulic retention time. The problems in this field of the CW-MFC systems were summarized and the potential applications in the future were prospected.

    Thermodynamic calculation and energy saving analysis of combined reaction system for production of dimethyl carbonate, methylal and dimethyl ether from methanol
    DING Xiaoshu, LI Naihua, WANG Shufang, ZHAO Xinqiang, WANG Yanji
    2015, 66(7):  2377-2386.  doi:10.11949/j.issn.0438-1157.20141673
    Abstract ( 319 )   PDF (779KB) ( 395 )  
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    To achieve the target of the efficient, green, safe and energy saving synthesis of dimethyl carbonate, a combined reaction system with energy saving is proposed for synthesis of dimethyl carbonate, methylal and dimethyl ether from methanol. Thermodynamics of single reaction and the complex system is analyzed by Aspen Plus software. The results show that there is thermodynamic equilibrium limit for the synthesis of dimethyl carbonate from methanol in gas phase, to improve significantly equilibrium concentration of dimethyl carbonate higher reaction pressure and lower reaction temperature is necessary, even so, large amount of unreacted methanol must be recycled which consume a lot of energy. When synthesis of dimethyl carbonate is combined with methylal and dimethyl ether synthesis, the equilibrium conversion of methanol can be improved observably from 0.5%—5.9% to 91.7%—96.3%. Based on the thermodynamic calculations and kinetics of these reactions, a series process of three catalytic reactors are proposed for synthesis of dimethyl carbonate, methylal and dimethyl ether in order, and the system including reaction and separation processes is simulated. The results show that the mixture of methylal and dimethyl carbonate can be separated by simple distillation and the separation of dimethyl carbonate-H2O azeotrpoe need to employ pressure swing distillation. Mass concentration of three products can be reached above 99%. The process proposed could effectively solve the problems as follows: recycle of large amount un-reacted materials, high energy consumption, easy explosion and so on, which exist in the process for detached production of dimethyl carbonate and methylal.

    Construction and application for VLE and pressure-enthalpy diagrams of R134a/R23/R14 zeotropic mixtures
    ZHANG Qingqing, ZHANG Hua, LOU Jiangfeng, LI Jia, ZHAO Wei, WANG Xi, LIU Zhanjie
    2015, 66(7):  2387-2394.  doi:10.11949/j.issn.0438-1157.20141676
    Abstract ( 309 )   PDF (847KB) ( 1248 )  
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    The thermodynamic properties of R134a/R23/R14 ternary mixtures used in three-stage auto-cascade refrigeration systems were calculated based on the PR equation, and enthalpy and entropy were calculated by using dryness. The diagrams of pressure-enthalpy and VLE of R134a/R23/R14 mixture under the typical composition were given. The deviations of bubble pressure and vapor composition between simulation results and the experimental data were less than 1.3% and 1.2% for R134a/R23, 1.0% and 2.4% for R32/R134a, respectively. The deviations of 95% calculated values of R32/R125/R134a were between ±5%. The simulation results could meet the requirements of engineering calculation. Based on the experiment, the thermodynamic properties of the auto-cascade refrigeration system were analyzed in detail. The pressure-enthalpy diagrams of R134a/R23, R23/R14 and R134a/R23/R14 under the operating compositions were given, and the diagram of spatial pressure-enthalpy described the circle of this system clearly. This simulation program could analyze the system circle effectively.

    Mixing characteristics and enhancement of excitation in mini confined impinging jets reactor
    DU Kejiang, LI Weifeng, SHAN Zhihao, LIU Haifeng, WANG Fuchen
    2015, 66(7):  2395-2401.  doi:10.11949/j.issn.0438-1157.20141811
    Abstract ( 268 )   PDF (2072KB) ( 475 )  
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    An experimental study is undertaken on liquid mixing process in mini confined impinging jets reactor (CIJR) with excitation by using planar laser induced fluorescence (PLIF) technique quantitatively, and the jet inlet Reynolds number is in the range of 75 to 150. The results show that the mixing effect of two fluids significantly increases during the segregated steady flow translates to the dynamic chaotic flow regime in CIJR. The excitation affects the mixing process in CIJR and the mixing performance is enhanced in the segregated flow regime. However, the excitation has no significant influence on the mixing for the flow in the oscillation regime.

    Characteristics of phase-concentration measurement for capacitance sensors in gas-liquid two-phase flow
    ZHAO An, HAN Yunfeng, ZHAI Lusheng, CHEN Chunyuan, JIN Ningde
    2015, 66(7):  2402-2410.  doi:10.11949/j.issn.0438-1157.20150166
    Abstract ( 233 )   PDF (2083KB) ( 791 )  
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    A capacitance measurement system for vertical upward gas-liquid two-phase flow has been established to explore the feasibility for measuring fluid phase-concentration by using concave capacitance sensor and double helix capacitance sensor. The experimental results prove that the concave capacitance sensor has poor measurement resolution, but double helix capacitance sensor shows high resolution in phase-concentration measurement. The fluctuation signals of the two types of capacitance sensors are analyzed by means of time frequency analysis. The time frequency representation can effectively identify flow patterns and characterize their motion clearly. Finally, the drift model of gas-liquid two-phase flow is employed based on the measurement signals of double helix capacitance sensor. Moreover, the phase superficial velocities are estimated for slug and churn flow patterns, and good prediction results are achieved. The results show that the double helix capacitance sensor possesses a good application prospect for measuring the flow parameter in gas-liquid two-phase flows.

    Flow and mixing characteristics of granular jet exposed to central and annular air jet
    LÜ Hui, WANG Haiyong, LI Dalong, CAO Guiping, LIU Haifeng, GUO Yanglong
    2015, 66(7):  2411-2419.  doi:10.11949/j.issn.0438-1157.20150088
    Abstract ( 206 )   PDF (3299KB) ( 338 )  
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    An experimental study was conducted on gas-particle coaxial jets by PIV and high-speed camera. The effects of the coaxial jets form and the addition of swirl on the flow and mixing characteristics of particle phase were investigated. The results showed that the axial velocity of the granular jet exposed to an annular air jet was higher than that of the granular jet with a central air jet. In addition, the mixing effect of the case with an annular air jet was found to be much better. For the two coaxial jets forms, the particle axial velocity profile in the cross-section close to the nozzle was more even. The addition of swirl, especially for the strong swirl, could not only achieve the uniform distribution of the particle axial velocity in the far field, but also improve the mixing effect of the two-phase efficiently.

    Mechanism of natural convection around heated microwire at low Rayleigh number
    DAI Chuanshan, WANG Jue
    2015, 66(7):  2420-2425.  doi:10.11949/j.issn.0438-1157.20150010
    Abstract ( 258 )   PDF (1294KB) ( 460 )  
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    The mechanism of natural convection around horizontal and vertical heated microwires in silicon oil is studied by using the wire itself for temperature measurement. The comparison between present measured Nusselt numbers and those in literature shows that the present data agreed better with those of Tsubouchi than those of Fand. The horizontal microwire presents a larger Nu than the vertical one at low Rayleigh number. However, all of these experimental Nu are much larger than the numerically simulated values. In order to give a theoretical explanation on this phenomenon, heated microwire with weak vibration was used in the numerical simulations. The simulated Nu shows a perfect match with the measured data and are in agreement with the correlation of Tsubouchi with a deviation less than 5%. Therefore, an enhanced heat transfer mode due to weak wire vibration is proposed, to fill the gap between simulated and experimental results.

    Heat and mass transfer characteristics of evaporation and salt crystallization process of a saline droplet during depressurization
    LIU Lu, WANG Mo, LIU Yan, BI Qincheng, LIU Yanfeng
    2015, 66(7):  2426-2432.  doi:10.11949/j.issn.0438-1157.20150022
    Abstract ( 371 )   PDF (976KB) ( 407 )  
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    A mathematical model was developed to simulate the heat and mass transfer of evaporation and salt crystallization process of a saline (aqueous NaCl solution) droplet during depressurization. The model considered the formation of porous salt crust at the droplet surface, the air flow around the droplet caused by pressure drop, the mass diffusion of vapor through porous medium and the heat transfers due to evaporation and convection at the droplet surface. By comparing the numerical results with the experimental data, the validity of the present model was verified. Through numerical calculations, the variations of droplet surface temperature and droplet mass with time were obtained, and the different characteristics of droplet evaporation and crystallization process under low pressure environment and atmospheric environment were analyzed. The results showed that the temperature variation of a saline droplet during evaporation and salt crystallization process under reduced pressure can be divided into four stages: the stage of temperature drop, the temperature recover stage, the equilibrium temperature stage, and the temperature rising stage. During the equilibrium temperature stage, the movement of salt crust interface was slower, with the evaporation process, the size of liquid core decreased continuously, and then the movement of salt crust interface was quicker. The effect of ambient pressure on evaporation and salt crystallization process of a brine droplet was theoretically analyzed. With a lower ambient pressure, the equilibrium temperature was lower and the time for salt completely precipitated was shorter.

    Visual experiment on evolution of flow pattern of R124-DMAC bubble absorption process in vertical tube
    JIANG Mengnan, XU Shiming, HU Junyong, WANG Wei, WU Xi
    2015, 66(7):  2433-2441.  doi:10.11949/j.issn.0438-1157.20150229
    Abstract ( 200 )   PDF (7500KB) ( 340 )  
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    Through constructing a visual experiment platform of bubble absorption heat and mass coupled transfer characteristics in the vertical tube, the flow pattern characteristic and distribution regularity of bubble absorption process on R124/DMAC (2-chloro-1,1,1,2,-tetrafluoroethane / N', N'- dimethylacetamide) as working medium are studied. The result shows that the flow pattern characteristic and distribution regularity are influenced by the refrigerant vapor flow rate, absorption solution flow rate and its inlet temperature. Under large refrigerant vapor flow rate and high solution inlet temperature conditions, three kinds of flow patterns of churn flow, slug flow and bubble flow can be simultaneously observed in the bubble absorption tube. Under the condition which the vapor is completely absorbed in the absorption tube, the height of churn flow is no more than half of the total absorption height, while the height of slug flow is no more than 2/5 of the total absorption height. The rest of the absorbing height is occupied by bubble flow.

    Condensation of vapor using sound pressure oscillation signals
    TANG Jiguo, YAN Changqi, SUN Licheng, LI Ya, WANG Kaiyuan
    2015, 66(7):  2442-2449.  doi:10.11949/j.issn.0438-1157.20150080
    Abstract ( 173 )   PDF (1511KB) ( 260 )  
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    Signals of sound pressure oscillations during vapor condensation and transition of condensation regimes were investigated using a high-speed video camera and a hydrophone. Results indicate three different condensation regimes with the increase of subcooling and vapor injection rates, which are referred to as bubble oscillation regime, transition regime and capillary wave regime. In addition, two waveforms occur in the detected signals, of which sources are vapor bubble split-up and collapse. The kurtosis of the signals presents step changes, which is close to the transformation threshold of condensation regimes. The peak at frequency of 150—300 Hz appears in spectra in all condensation regimes, which may be resulted from the periodic variation in vapor volume. The peaks with frequency higher than 7000 Hz appear only in transition and capillary wave regimes and may be the resultant of the high-frequency oscillation in pressure caused by sudden collapse of vapor bubbles. The bubble collapse frequency increases with the increase of subcooling and vapor injection rates and is close to the frequency of the first peak in spectra with an error within ±20%.

    Experimental study and mechanism analysis of liquid morphologies in particle packing porous medium
    YU Mingzhi, FAN Xuejing, HU Aijuan
    2015, 66(7):  2450-2455.  doi:10.11949/j.issn.0438-1157.20141667
    Abstract ( 167 )   PDF (2918KB) ( 314 )  
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    The particles aggregation states and apparent volume of the stacked glass beads at different liquid content are studied experimentally. It shows that the liquid mainly exist as liquid bridges at low liquid content, while that in different pores connects to each other at higher liquid content. The apparent contact angle of water on particle surface determines the critical moisture content which separates the low and high moisture content. The transformation of liquid morphologies induces the variation of the liquid action on particles, which finally influences the particles aggregate state and leads to the change in the sample apparent volume. A model is developed to determine the critical liquid content by the apparent contact angle, from which the liquid begins to mainly exist as interconnectedness morphology other than isolated liquid bridges. The prediction from the model is in good agreement with the experimental data.

    Local heat transfer characteristics for forced convection condensation of steam/air in horizontal tube
    XU Huiqiang, SUN Qiunan, GU Haifeng, LI Hao, SUN Zhongning
    2015, 66(7):  2456-2463.  doi:10.11949/j.issn.0438-1157.20150046
    Abstract ( 187 )   PDF (957KB) ( 605 )  
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    An experimental investigation on forced convection condensation of steam with air in a horizontal tube was presented. Based on the results of flow regime prediction, influences of air mass fraction, velocity and pressure of the mixture gases and inner wall sub-cooling on local condensation heat transfer were analyzed. According to the experiment results, local heat transfer coefficient always decreased with the increase of air mass fraction and increased with the increase of total mixture gases pressure. For annual flow, the local heat transfer coefficient was affected by the mixture velocity, and for wavy flow, the ability of local heat transfer was influenced greatly by the air mass fraction and development of wavy flow, while for stratified flow, the effect of wall sub-cooling on heat transfer was dominated.

    Orthogonal test of self-pumping mechanical seals based on numerical simulation
    GU Dongsheng, SUN Jianjun, MA Chenbo, LU Jianhua
    2015, 66(7):  2464-2473.  doi:10.11949/j.issn.0438-1157.20150204
    Abstract ( 201 )   PDF (1441KB) ( 780 )  
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    A kind of self-pumping hydrodynamic mechanical seal, that the liquid inlet groove was arranged on the stationary ring and the dynamic pressure groove was distributed on the rotating ring, was put forward based on the principle of centrifugal pump. The experimental scheme of the self-pumping mechanical seals was designed by orthogonal test. The numerical simulation experiments were carried out based on Fluent, including discussing the significant effects of every parameter on the face opening force and the leakage rate. The numerical results showed that the groove number Ng, the ratio of groove length and dam length γ, the ratio of groove width and ridge width d, and the pressure p were the significant factors affecting the opening force FO and the leakage rate Q within the experimental ranges. Besides, the rotate speed n also affected Q significantly. Specifically, FO was increased with increasing g, d and p, while decreased with increasing Ng. The influence of g, d, p and Ng on Q was similar to that on FO. But Q was also increased with increasing n. The preliminary optimization of sealing structure was brought forward by analyzing the results of orthogonal test.

    Characteristic of ligament in centrifugal granulation by spinning disc
    WU Junjun, WANG Hong, ZHU Xun, LIAO Qiang, LI Jun, LIN Lin
    2015, 66(7):  2474-2480.  doi:10.11949/j.issn.0438-1157.20150008
    Abstract ( 241 )   PDF (2518KB) ( 594 )  
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    Aiming at the granulation of molten blast furnace slag by spinning disc, the visualization granulation experiment was conducted using water as the substance. The granulation process including film waving and ligament break-up was captured by high-speed camera. A self-compiled MATLAB program was employed to extract the data from the images. The ligament formation and the process of ligament break-up into droplets during centrifugal granulation were analyzed. Variation of ligament formation and droplet formation with operating conditions was investigated. The qualitative relationship between ligament formation and droplet formation was obtained. The impacts of Weber and Reynolds numbers on ligament number, ligament break-up length, droplets diameter distribution and average diameter were discussed. The results revealed that the ligaments were originated from surface instable waves of liquid film on the spinning disc and the droplets were formed by ligament break-up due to symmetric shocking waves spreading from the ends to the middle of ligament. The number of ligament increased with increasing rotary speed and the distribution of droplets became more highly concentrated as well, while the break-up length of ligaments and the average diameter of droplets were decreased as rotary speed increased. With increasing liquid flow rate, the number of ligaments increased, while the distribution of droplets became less concentrated. The break-up length of ligaments and average diameter were increased with higher liquid flow rate. Besides, larger ligament number or shorter ligament break-up length resulted in smaller droplets. Meanwhile, both of the Weber and Reynolds numbers had significant influence on the ligament formation, while only the Weber number had significant effect on droplet formation. By fitting the experimental data, correlations have been obtained to predict the granulation variation with different operational conditions quantitatively.

    Isobutane alkylation catalyzed by ether functionalized ionic liquids
    LU Dan, ZHAO Guoying, REN Baozeng, JIANG Zhenxi, ZHANG Suojiang
    2015, 66(7):  2481-2487.  doi:10.11949/j.issn.0438-1157.20150233
    Abstract ( 367 )   PDF (626KB) ( 580 )  
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    A series of acidic ether functionalized chloroaluminate ionic liquids were synthesized and studied. The catalyst with the highest acidity was screened out by FT-IR spectra using acetonitrile as infrared probe and used to catalyze the alkylation of isobutane with 2-butene. It was proved that the acidity of 1-methoxyethyl-3- methylimidazolium bromide aluminium chloride ([MOEMIM]Br/AlCl3) was the highest when the molar ratio of AlCl3 was 0.75. The high quality alkylate with a C8 selectivity of 66.6%(mass) was obtained at 35℃ with the isoparaffin/olefin molar ratio (I/O) of 10, which was much better than that with non-ether functionalized chloroaluminate ionic liquids. The catalysts could be reused several times without obvious loss of activity.

    Heteropolyanion-based ionic liquids catalyze esterification of ammonium succinate in aqueous solution
    ZHANG Feng, LIANG Jinhua, HU Xi, WANG Junge, CHEN Liulong, REN Xiaoqian, JIANG Min
    2015, 66(7):  2488-2497.  doi:10.11949/j.issn.0438-1157.20150131
    Abstract ( 203 )   PDF (687KB) ( 507 )  
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    Propane sulfonate (PS) functionalized organic cations were combined with Keggin heteropolyanions to synthesize a series of sulfonated organic heteropolyacid salts (HPA-ILs). Their structures were characterized by FT-IR and elemental analyses (C, H, N). These catalysts were applied to directly catalyze the esterification of ammonium succinate with 1-butanol in aqueous solution. Compared with HPAs, H2SO4, [MIMPS]HSO4 and Nafion®NR-50 resins, HPA-ILs exhibited excellent catalytic activities. Finally, the excellent catalyst [MIMPS]3PMo12O40 was selected to investigate systemically the reaction conditions. The optimization of the reaction conditions was ammonium succinate concentration 50% (mass), catalyst dosage 1.0% (based on ammonium succinate), n(1-butanol):n(ammonium succinate)=5:1, reaction time 12 h, reaction temperature 130℃ and vacuum degree 0.02 MPa. The highest yield of esters could reach 89.7%. After reusing 6 times the catalyst still showed the superior catalytic performance with yield of above 85%.

    Model considering catalyst deactivation kinetics and equilibrium activity for catalytic cracking unit
    REN Jie, REN Yongmo, YUAN Haikuan
    2015, 66(7):  2498-2504.  doi:10.11949/j.issn.0438-1157.20141892
    Abstract ( 284 )   PDF (573KB) ( 581 )  
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    Based on the flow pattern of perfect mixing and the age probability density exponential function of equilibrium catalyst in commercial FCC unit, a model equation was established by derivation of catalyst deactivation kinetics, in which equilibrium catalyst activity or micro-reactor activity was related to carbon and metal contents on catalyst, replacement rate of catalyst, temperature and steam partial pressure in regenerator. The mathematical model with high calculation precision for equilibrium catalysts activity or micro-reactor activity was developed through the simulation for operation data of commercial FCC unit and model parameter estimation. The comparison of model parameters indicated that the effect of V contaminate on catalyst activity is the biggest and the effect of Na is the smallest, while the effect of Ni and Fe is in the middle. The results predicted by the model showed that the activity or micro-reactor activity of equilibrium catalyst increases with the decrease of metal and carbon contents on catalyst and the increase of catalyst consumption. It would be advantageous to the activity or micro-reactor activity of equilibrium catalyst to reduce properly the catalyst hold-up or the temperature in regenerator.

    Effect of support on catalytic performance of nickel-based catalysts used for liquid phase hydrogenation of maleic anhydride
    ZHANG Yin, ZHAO Lili, ZHANG Hongxi, LI Haitao, LIU Panpan, GE Yuanyuan, ZHAO Yongxiang
    2015, 66(7):  2505-2513.  doi:10.11949/j.issn.0438-1157.20150020
    Abstract ( 270 )   PDF (631KB) ( 906 )  
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    Nickel-based catalysts supported on ZrO2, SiO2, and Al2O3 supports, were prepared by incipient impregnation method and evaluated using liquid phase hydrogenation of maleic anhydride. BET,XRD,H2-TPR and TPO-MS were employed to characterize these catalysts. Their catalytic performance varied with supports used. Among all the catalysts, Ni/Al2O3 catalyst exhibited the highest activity for C=C hydrogenation, while there was the lowest activity for C=O hydrogenation. Ni/ZrO2 catalyst had the highest C=O hydrogenation activity, and maleic anhydride conversion and γ-butyrolactone selectivity were 100% and 79.2% respectively under the reaction condition of 483 K, 5 MPa of H2 and 8 h of reaction time. The re-use experiment of catalyst demonstrated that the stability of catalyst in liquid phase hydrogenation of maleic anhydride was better for Ni/ZrO2 and Ni/SiO2 than Ni/Al2O3. Both selectivity and stability of catalysts could be explained by the interaction between succinic anhydride and catalyst.

    Hydrodesulfurization performance of TiO2-graphene oxide composite support prepared by electro-spinning
    WANG Huaiyuan, XIAO Bo, WANG Chijia, CHENG Xiaoshuang, JIANG Feng
    2015, 66(7):  2514-2520.  doi:10.11949/j.issn.0438-1157.20141781
    Abstract ( 171 )   PDF (1165KB) ( 718 )  
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    Novel TiO2 nanofibers(NF) and TiO2(NF)-graphene oxide (GO) supports were prepared by electro-spinning, and NiMo/TiO2(NF) and NiMo/TiO2(NF)-GO catalysts were obtained by incipient impregnation. The properties of supports and catalysts were characterized by N2 absorption-desorption, X-ray diffraction, SEM, TEM, Raman spectra and NH3-TPD. The effect of different loading of GO was investigated. The results showed that when the mass fraction of GO/TiO2(NF) was 0.5%, the intermediate-strong acid sites increased to the maximum. Under the mild conditions of 280℃, 2.0 MPa, LHSV 4 h-1 and H2/feed ratio 400 (vol), the corresponding catalyst exhibited the excellent HDS performance.

    Synthesis of cis-1,4-polyisoprene with low-temperature prepared Ti-Al catalysts
    WANG Zhaowei, YU Junwei, LI Xing, LIU Xiaoxuan
    2015, 66(7):  2521-2527.  doi:10.11949/j.issn.0438-1157.20150032
    Abstract ( 228 )   PDF (640KB) ( 397 )  
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    The high cis-1,4-polyisoprene is prepared by Ziegler-Natta coordination polymerization. The effect of preparation method and condition of heterogeneous TiCl4-Al(i-Bu)3 two component catalyst on isoprene polymerization are investigated. The influence of several parameters on the catalytic activity, the gel content, intrinsic viscosity, microstructure and cis-1,4-content of the polyisoprene is examined in detail, including mole ratio of catalyst component, prefabricate temperature and aging time as well as catalyst dosage, polymerization temperature and time. The results show that the optimum conditions of catalyst preparation are as follows: the molar ratio of Al/Ti is 1.0, the temperature of prefabricate is at -40℃, the aging time is 2 h at room temperature, molar ratio of Ti/Ip(catalyst content)is 6×10-3, the polymerization for 5 h at 50℃. Under these condition, the monomer conversion is 87.1% in the polymerization, the microstructure cis-1,4 content in obtained polymer is up to 91.76%.

    Optimization of acid hydrolysis for preparing L-arabinose from Gum Arabic
    HUANG Minhui, BAO Zongbi, DUAN Shuran, XING Huabin, YANG Yiwen, REN Qilong
    2015, 66(7):  2528-2533.  doi:10.11949/j.issn.0438-1157.20150378
    Abstract ( 270 )   PDF (602KB) ( 317 )  
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    Gum Arabic, an ideal raw material for preparing L-arabinose, can be catalytically hydrolyzed by sulfur acid to obtain the hydrolysate containing L-arabinose, D-galactose and L-rhamnose. In order to ensure the stability of subsequent purification process as well as product quality, optimization of the acid hydrolysis process is necessary. In this work, single factor experiments are performed to determine the key parameters of acid hydrolysis reaction. The effects of reaction time, acid concentration, temperature and solid-to-liquid ratio on the hydrolysis are investigated. The results show that the temperature affects more significantly on the yield rate of L-arabinose. The degree of hydrolysis as high as 85% and the relative purity of L-arabinose up to 85% or 87% can be obtained under the optimized hydrolysis conditions of 90 min reaction at 100℃ or 200 min reaction at 90℃ with 0.1 mol·L-1 H2SO4 and solid-to-liquid ratio of 1:10 (g/ml).

    Structural and catalytic characteristics of temperature-responsive lipase catalyst in organic solvents
    YONG You, ZHU Jingying, LU Diannan, GE Jun, LIU Zheng
    2015, 66(7):  2534-2539.  doi:10.11949/j.issn.0438-1157.20150068
    Abstract ( 270 )   PDF (1476KB) ( 301 )  
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    Pluronic polymers P123, P105, F127 and F108, which have different chain lengths of PEO block were modified to generate aldehyde terminals for the conjugation with surface amine groups of CALB. The resulted Pluronic-CALB conjugates were characterized by SDS-PAGE and transmission electron microscopy. It was showed that the conjugates were dispersed well in toluene and appeared as nanoparticles with diameters ranged from 20 nm to 40 nm. The conjugates can be dispersed in methyl isobutyl ketone (MIBK) with temperature- responsive properties. The conjugate with a longer chain length of PEO block appeared a higher low critical solution temperature (LCST). The apparent activity of the conjugates in toluene at 37℃ was increased by 4 to 6 folds compared to the native counterpart. The recovery of CALB conjugates can be accomplished by precipitation at low temperature, making this enzyme conjugate suitable for industrial enzymatic synthesis in organic media.

    Adsorption mechanism of H2 on covalent organic frameworks
    YANG Xiao, LIU Jing, HU Jianbo
    2015, 66(7):  2540-2546.  doi:10.11949/j.issn.0438-1157.20150117
    Abstract ( 349 )   PDF (3292KB) ( 1187 )  
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    Covalent organic frameworks (COFs) are considered as a new type of adsorbing material for hydrogen. In this work, density functional theory (DFT) has been applied to investigate the adsorption mechanism of H2 on seven main clusters of COFs, and GGA/PBE is used in the calculation. The results indicate that the center of benzene ring is the most favorable site when H2 molecular attacks vertically, in addition the center and oxygen atom of B3O3 ring are more favorable when H2 molecular attacks parallelly. The increase of carbon atom number on organic cluters would be beneficial for adsorption of H2. By calculation of different adsorption configurations for two H2 molecules on COF-10 and COF-105, it is found that a cooperative effect between H2 adsorption on these two COFs could be exist. Doping of alkali metals (Li, Na, K) and substitution of organic functional groups (methyl, sulfhydryl, amino) on COFs can significantly enhance the adsoroption energy, indicating that these chemical modifications are an effective way for enhancement of hydrogen adsorption capacity of COFs.

    A code matrix-based method for distillation sequences synthesis
    XU Yan, ZHANG Chunxia, WANG Ruxian, LÜ Jing, ZHAO Yujun, MA Xinbin
    2015, 66(7):  2547-2554.  doi:10.11949/j.issn.0438-1157.20141938
    Abstract ( 196 )   PDF (576KB) ( 550 )  
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    A code matrix-based synthesis method for multicomponent distillation sequences is described as well as its algorism. Four steps, such as grouping the components of feed, generating the basic search space of sub-column configurations, transforming 0-1 matrices into code matrices and eliminating configurations with separation constraints, are included in this method. The code matrices, whose element code includes the information about the column sequence number and the location of product withdrawing, are transformed from 0-1 matrices determined by matrix method. Thus, this method not only provides a complete set of separation configurations with sharp or non-sharp split but also can pick out all the desirable configurations with the constraints by logical programming. Additionally, the use of this method is illustrated by applying it to the ethylene glycol purification from dimethyl oxalate hydrogenation. Eight configurations are selected out and one configuration with the lowest total reboiler heat duty is identified by Aspen Plus optimization.

    Nanofiltration performance and mass transfer characteristics of PDMS/PVDF composite membranes filled with white carbon black
    CAI Weibin, XIA Yang, WANG Yujun, LI Jiding, ZHU Shenlin
    2015, 66(7):  2555-2564.  doi:10.11949/j.issn.0438-1157.20141691
    Abstract ( 258 )   PDF (2778KB) ( 480 )  
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    Nano white carbon black particles filled PDMS/PVDF composite membranes were prepared, and FT-IR, TGA and contact angle were used to characterize the physical and chemical characteristics of the composite membranes. By using soybean/hexane miscellas, the separation performance of the composite membranes was systematically investigated. The results indicated that by filling white carbon black to PDMS, the crosslinking density was promoted, and the hydrophobicity, thermal stability and solvent resistance were improved. The permeate flux was declined with increasing filling content of white carbon black, while the oil retention was risen from 96% to 98%. With the increase of oil concentration, both of the permeate flux and oil retention were declined. With increasing feed temperature, the permeate flux was risen while the oil retention was declined. Mass transfer characteristics of soybean oil and hexane through the membrane can be described by the solution-diffusion with imperfections model, and the experimental values of the micelle osmotic pressure were well in accordance with calculated values.

    Synthesis of porous carbon through polymerization catalyzed by basic magnesium carbonate and their CO2 adsorption performance
    WANG Enmin, LI Wencui, LEI Cheng, LU Anhui
    2015, 66(7):  2565-2572.  doi:10.11949/j.issn.0438-1157.20141744
    Abstract ( 171 )   PDF (935KB) ( 307 )  
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    By taking the advantages of easy decomposition and catalytic function of basic magnesium carbonate, the mechanically stable porous carbon materials (MCM-Mg) are synthesized through rapid gelation of resorcinol with formaldehyde and subsequently carbonization. Compared with samples catalyzed by traditional carbonates, the synthesis process can obtain a well-developed porous structure. The resulted samples can withstand a pressure of up to 9.4 MPa. At 273 K, the equilibrium CO2 adsorption capacities of MCM-Mg are in the range of 3.49—4.50 mmol·g-1 at 0.1 MPa and can reach 1.87 mmol·g-1 at 0.015 MPa. Experimental test of the MCM-Mg shows that the micropores play a major role in contribution of the amount of adsorbed CO2. Importantly, MCM-Mg can adsorb 7.15 μmol CO2 per Smicro, which surpasses most of the carbons prepared by activation. Dynamic breakthrough tests show that over such series of samples, CO2/N2 streams can be fully separated. The CO2 release is achieved facilely in Ar purge at 298 K. The samples also exhibit stable performance for CO2 separation under humid conditions and exhibit good regeneration capability.

    Batch-to-batch self-optimizing control for batch processes
    YE Lingjian, SONG Zhihuan, MA Xiushui
    2015, 66(7):  2573-2580.  doi:10.11949/j.issn.0438-1157.20150247
    Abstract ( 298 )   PDF (584KB) ( 406 )  
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    For real-time optimization of batch processes, a batch-to-batch self-optimizing control approach is proposed based on necessary conditions of optimality approximation method. Firstly, the nominal optimal input trajectory is numerically obtained, which is further parameterized as a few decision variables to simplify the problem complexity. Secondly, the optimality conditions for the batch-to-batch optimization problem are analyzed, from which regression models are built using terminal measurements. The obtained regression models are further adopted as controlled variables to be tracked from batch to batch. The proposed method is applied to a simulated batch reactor. The results show that the new method can realize batch-wise self-optimizing control efficiently.

    Water network optimization with temperature constraints
    LI Ruizhen, FENG Xiao, WANG Yufei
    2015, 66(7):  2581-2587.  doi:10.11949/j.issn.0438-1157.20150142
    Abstract ( 160 )   PDF (486KB) ( 162 )  
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    In a practical water using process, a temperature requirement exists. Thus, it is significant to consider the temperature constraint in water network integration to decrease the water and energy consumption at the same time. Besides, there are non-water process streams which only have temperature requirements in the process system. If these streams are integrated with water streams in the water network, better energy efficiency can be reached. In this paper, a method for optimizing water networks is proposed under the background of heat integration in whole process system. First, an LP model is established to obtain the initial status of the water network and stream data. Then, four rules for non-isothermal mixing are proposed by comparing the relative position of water streams with the background and whole process pinches to exclude the irrational non- isothermal mixing. Finally, the heat integration in the whole system is performed with minimal total annual cost as the objective function. A case study is used to show the feasibility of the method, which can get a decrease of 6.27% in the annual cost.

    On-line prediction model for concentrations of zinc ion and sulfuric acid inzinc electrowinning process
    DENG Shijun, YANG Chunhua, LI Yonggang, ZHU Hongqiu
    2015, 66(7):  2588-2594.  doi:10.11949/j.issn.0438-1157.20141569
    Abstract ( 291 )   PDF (760KB) ( 392 )  
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    The concentrations of zinc ion and sulfuric acid in electrolytic solution are detected by off-line analysis with large time-delay, which will be detrimental to the on-line optimal control for zinc electrowinning process (ZEWP). It is very significant to predict the concentrations of zinc ion and sulfuric acid on line. The electrochemical reaction mechanism for ZEWP is analyzed, and a dynamic model for ZEWP is established based on the material balance and electrochemical equations. Based on the data collected from the practical ZEWP, the working conditions of the ZEWP are classified using FCM algorithm. The parameters of the dynamic model under different classes are identified, and the concentrations of zinc ion and sulfuric acid in ZEWP are predicted using the multi-condition fuzzy matching approach. The results obtained from the practical data show that the model can effectively predict the variation tendency of the concentrations of zinc ion and sulfuric acid, which is profitable to the optimal control for ZEWP.

    Optimization based on particle swarm algorithm for leaching rate ofgold hydrometallurgy process
    YUAN Qingyun, WANG Fuli, HE Dakuo, WU Chang
    2015, 66(7):  2595-2600.  doi:10.11949/j.issn.0438-1157.20141924
    Abstract ( 232 )   PDF (556KB) ( 297 )  
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    Rational allocation of leaching rates is significant for the organization of leaching process production. Generally, each leaching rate is given by engineers with the help of their experiences, which makes the supervision of leaching process production with a large extent of fuzziness and randomness, and it does not guarantee that the adjusted total leaching rate is the maximum. In order to determine the optimal leaching rate of gold hydrometallurgy process, an optimization model is established with maximizing the total leaching rate of hydrometallurgy process as the goal. And the second-order oscillating particle swarm algorithm is applied to solve the model. Finally, an experimental research demonstrates the effectiveness of the established model and algorithm.

    Influence of CO2 fraction on micro interfacial properties of miscible(CO2+n-hexane)/NaCl interface
    TAO Lu, ZHAO Lingling, WANG Jingfan
    2015, 66(7):  2601-2606.  doi:10.11949/j.issn.0438-1157.20150104
    Abstract ( 275 )   PDF (1482KB) ( 353 )  
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    In the geological carbon dioxide (CO2) sequestration in abandoned oil reservoirs, there usually exists a fluid system including CO2, oil and brine, where the interplay between them is very important for the successful CO2 storage. In this paper, molecular dynamics simulations were carried out to investigate the interfacial characteristics of the CO2, n-hexane and NaCl solution system with different CO2 fractions at the miscible state. CO2 and n-hexane formed a miscible phase, and a clear interface was observed to separate the CO2 and n-hexane mixture with brine. Both the interfacial width and roughness increased with increasing CO2 composition, indicating the stronger interfacial interactions when water molecules contacted with CO2, leading to the reduction of interfacial tension. The surface adsorption of CO2 reached the maximum when CO2 molar fraction equaled to 65%, as well as the deficiency of n-hexane. This implied the surfactant feature of CO2 and the hydrophobicity of n-hexane towards the interface investigated. A special micro structure was observed at the interface, where CO2, water and n-hexane molecules had own preferred arrangement tendency. The special interfacial characteristics found could explain the experimental IFT phenomena and the microstructure variation in the CO2 injecting process, and could provide some theoretical guidance for CO2 sequestration.

    Stability of corrosion inhibitor film of high sulfur gas gathering pipeline
    CHEN Siwei, LIU Dexu, GONG Jinhai
    2015, 66(7):  2607-2612.  doi:10.11949/j.issn.0438-1157.20141825
    Abstract ( 307 )   PDF (2108KB) ( 291 )  
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    Aiming at the stability problem of corrosion inhibitor film of the high sulfur gas gathering pipelines with two-phase turbulent flow, the corrosion inhibitor film stability with typical pipe flow in high sour gas field was evaluated by using the dynamic corrosion test system with high temperature and high pressure cyclic reactor. The inhibitor prefilm stability was better when the flow velocity was below 6 m·s-1 and it began partial failure when the flow rate exceeded 7.5 m·s-1, while it was completely failure under the action of flow shear force when the flow rate reached 9 m·s-1. The fluid dynamics study showed that the shear stress of 6.5 N·m-2 was the critical point of the inhibitor film being overall damaged.

    Construction and application of temperature sensitive thermotolerant systemin Escherichia coli
    JIA Haiyang, SUN Huan, SUN Xiangying, FENG Xudong, LI Chun
    2015, 66(7):  2613-2619.  doi:10.11949/j.issn.0438-1157.20141929
    Abstract ( 252 )   PDF (1574KB) ( 765 )  
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    The heat stress produced in fermentation process can not only affect the growth and reproduction of microorganisms, but also increases production cost from cooling and temperature control. The improvement of strain thermotolerance is highly desire for fermentation industry, which could significantly go up productivity and reduce production cost. So in this study, an artificial design and synthesis RNA switch with temperature sensitivity is employed to regulate and control the heat shock protein Dnak from Thermoanaerobacter tengcongensis MB4, which leads to the thermotolerance improvement of Escherichia coli. This improvement not only alleviated the burden of overexpressing heat shock protein in Escherichia coli at 37℃, but also enhanced its productivity at high temperature. The results of application test show that at 40℃ the output of lysine produced by E. coli increases by 2.95 folds, when compared with control group. This success could be twilight for the development of new method to prepare thermotalerance microorganisms.

    Biosynthesis of D-1,2,4-butanetriol from D-xylose by recombinantEscherichia coli
    MA Pengfei, MENG Jian, ZHOU Jing, GAO Haijun
    2015, 66(7):  2620-2627.  doi:10.11949/j.issn.0438-1157.20141703
    Abstract ( 263 )   PDF (724KB) ( 741 )  
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    1,2,4-Butanetriol (BT) is an important organic synthetic intermediate. In this study, the metabolic network of Escherichia coli was reconstructed by heterogeneously expressing a keto acid decarboxylase (mdlC) from Pseudomonas putida ATCC12633 and a D-xylose dehydrogenase (xdh) from Caulobacter crescentus CB15, and knocking out xylA, yjhH and yagE which were the genes of xylose utilization pathway and intermediary metabolite pathway for D-1,2,4-butanetriol synthesis. The recombinant strain could synthesize D-1,2,4-butanetriol directly using D-xylose as precursor. Culture conditions such as temperature, medium volume, pH of fermentation broth were investigated at the titer of D-1,2,4-butanetriol of 3.96 g·L-1 under suitable fermentation conditions. The relationship between glucose utilization and D-1,2,4-butanetriol synthesis was discussed. After modifying the phosphoenolpyruvate: sugar phosphotransferase system (PTS) by knocking out ptsG the reconstructed E.coli could utilize glucose and xylose simultaneously, leading to a higher D-1,2,4-butanetriol productivity.

    Drying process of Hulun Buir brown coal under isothermal condition
    SUN Xiaolin, GUO Xiaolei, LU Haifeng, GONG Xin
    2015, 66(7):  2628-2635.  doi:10.11949/j.issn.0438-1157.20141566
    Abstract ( 169 )   PDF (610KB) ( 186 )  
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    The drying characteristics under isothermal condition of Hulun Buir pulverized brown coal with high moisture content of 40% was studied using thermo-gravimetric method. The effects of drying temperature and particle size on drying process were analyzed. The results showed that the constant rate stage was obviously observed, and the characteristics were closely related to drying temperature and free water content. The critical (MCcr) and equilibrium (MCeq) moisture content were obtained. The drying rate decreased with the decrease of particle size, but the effect of particle size was not obvious when the coal particle was enough small. MCcr and MCeq decreased with the increase of temperature, however, MCcr increased and MCeq decreased slightly with the decrease of particle size. The experimental results could provide a basis of selection and optimization of brown coal powder and drying process.

    Promotion of ascorbic acid on oxidation of NO by Fe2+/H2O2 system
    ZHAO Haiqian, GAO Jihui, ZHOU Wei, WANG Zhonghua, WU Shaohua
    2015, 66(7):  2636-2642.  doi:10.11949/j.issn.0438-1157.20141920
    Abstract ( 173 )   PDF (526KB) ( 429 )  
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    The influences of ascorbic acid (AA), which is a low cost and eco-friendly additive agent, on NO oxidation and H2O2 decomposition in Fe2+/H2O2 system were experimentally studied and their reaction mechanisms analyzed. The results demonstrated that AA can improve oxidation of Fe2+/H2O2 system for NO through accelerating the reduction from Fe3+ to Fe2+. [AA]0:[Fe2+]0 ratio has important effect on oxidization ability and H2O2 decomposition of the system. Taken together the amounts of NO oxidized and H2O2 decomposition, the appropriate ratio of [AA]0:[Fe2+]0 should be between 1/3 to 1/2. Batch add of AA can greatly enhance the oxidation ability of Fe2+/H2O2 system for NO. These results would be a theoretical basis for the development of NO oxidation technology by H2O2.

    Effect of Zn, Cd compounds on formation of dioxins in model fly ash
    LIAO Junhong, YANG Jie, MENG Weijie, LI Xiaodong, CHEN Tong
    2015, 66(7):  2643-2648.  doi:10.11949/j.issn.0438-1157.20150034
    Abstract ( 270 )   PDF (582KB) ( 416 )  
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    Catalyst is the key factor for formation of dioxins i.e. PCDD/Fs, for which there is not enough study currently. In this paper, the effect of different metal catalyst contained in model fly ash (MFA) on both PCDD/Fs concentration and distribution is studied under laboratory conditions. The results show that ZnO can inhibit the formation of PCDD/Fs. The catalytic effect of ZnCl2 on PCDD/Fs is far more obvious than that of CdCl2 and the concentrations of PCDD/Fs obtained are 341.78 and 16.32 ng·g-1, respectively. PCDD/Fs formed by ZnCl2 promotion is 338 times as many as that of ZnO, while the concentration of PCDD/Fs catalyzed by CdCl2 is twice more than that of CdO. Principal component analysis (PCA) is used to research the effect of catalyst on PCDD/Fs distribution. It is observed that the change of distribution for 17 toxic PCDD/Fs catalyzed by different metal catalyst is significant. Meanwhile, the PCDD/Fs concentration rises with increase of O2 content, but for PCDD/Fs distribution it has only limit influence.

    Development of online monitoring and evaluation device for treatment of circulating cooling water
    CAO Shengxian, ZHAO Zhenchao, LI Sibo, CHEN Yanfei, FU Congwei, REN Jibing, FENG Baozhu
    2015, 66(7):  2649-2655.  doi:10.11949/j.issn.0438-1157.20141859
    Abstract ( 189 )   PDF (583KB) ( 570 )  
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    A new online monitoring and evaluation device for the treatment countermeasures of circulating cooling water was developed,which is used for evaluation and optimization of water treatment countermeasures, and online monitoring of the core water quality parameters. This device can online monitor the heat exchanger fouling resistance, corrosion rate and core water quality parameters (pH, ORP, concentrated ratio) in real-time based on the fluid state, water quality, metal materials and heat transfer intensity of the power plant circulating cooling water, and can evaluate and adjust the concentration of the water treatment agent online. The monitoring system hardware including fouling resistance detector, corrosion rate detector, automatic dosing device, analysis instrumentation of water quality parameters and industrial computer was designed. And the software was developed by Delphi7.0 which can carry out monitoring parameter settings, real-time display, online control, historical data query and report printing. This device has been used in Unit 1 of the Power Plant of Shandong Yancon Croup Co., Ltd. The experimental results showed that the instantaneous fouling resistance and corrosion rate were less than 1.5×10-4 m2·K·W-1 and 0.005 mm·a-1, respectively, and the concentration ratio of the circulating cooling water can increase from 2 times to 4 times. This device can evaluate the water treatment dosing programs in real-time, inhibit the growth of fouling resistance effectively, reduce the corrosion of the heat exchanger and improve the economic efficiency of power plants.

    Pyrolysis of coal with different moisture contents in fixed-bed reactorwith internals
    HU Erfeng, ZHANG Chun, WU Rongcheng, FU Xiaoheng, XU Guangwen
    2015, 66(7):  2656-2663.  doi:10.11949/j.issn.0438-1157.20141772
    Abstract ( 189 )   PDF (681KB) ( 470 )  
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    The effects of coal moisture on heating rate and product distribution for pyrolysis of coal in a fixed-bed reactor with or without internals were investigated. The results showed that the reaction time in the reactor without internals is approximately twice of the time in the reactor with internals. With utilization of internals to enhance heat transfer and regulate the pyrolysis gas flow direction inside the reactor, increasing the coal moisture content prolonged the time that required to heat up the coal at the bed center to the preset temperature and increased the light tar content, whereas the tar yield tended to first increase and then decrease and the yields of pyrolysis gas and water tended to increase. In contrast, there was not dramatic difference in the reactor without internals when varying the coal moisture. At a heating furnace temperature of 900℃, the increase of coal moisture from 0.41% to 11.68% (mass) increased the tar yield from 9.21% to 10.74% (mass) for the reactor with internals, but when the coal moisture content increased further to 15.93% (mass) the tar yield decreased to 10.26% (mass). The variation trend with coal moisture content in the average pyrolysis gas composition was similar for both reactors, and the higher heating value (HHV) became lower when the coal moisture increased.

    Influence of pyrolysis temperature on biochar stability and leaching properties of nutrients contained in biochar
    LU Tao, YUAN Haoran, WANG Yazhuo, HUHETAOLI, CHEN Yong
    2015, 66(7):  2664-2669.  doi:10.11949/j.issn.0438-1157.20150253
    Abstract ( 228 )   PDF (510KB) ( 525 )  
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    The biochar was produced from sewage sludge by pyrolysis at 300, 500 and 700 ℃. In this study the biochar degradation rate represented by CO2 release rate through alkali absorption method in microbial incubation was investigated and the half-life using a recommended prediction method was predicted. In addition, deionized water was used to investigate the content and leaching properties of the water-soluble nutrients contained in biochar. During the temperature range of 300—700℃, the biochar produced at higher temperature was degraded slowly and had longer half-life, which may exist in soil for a longer time span and then perform a better effect on carbon sequestration than that produced at lower temperature. However, biochar produced at lower temperature contained more water-soluble N and K but less water-soluble P, which was agreed with the concentration of leaching nutrients. The leaching water of biochar produced at lower temperature also contained more much water-soluble N and K but less water-soluble P.

    Influence of final retorting temperature on composition and property of Huadian shale oil
    WANG Qing, CUI Da, CHI Mingshu, ZHANG Hongxi, XU Xiangcheng
    2015, 66(7):  2670-2677.  doi:10.11949/j.issn.0438-1157.20150210
    Abstract ( 191 )   PDF (703KB) ( 403 )  
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    Oil samples, obtained by retorting Huadian oil shale at five different final temperatures, were divided, according to boiling point, into light oil (<300℃) and heavy oil (>300℃). The light oil was analyzed using GC-MS and their components classified to find the regular pattern that is variation of oil chemical composition with final retorting temperature. 1H and 13C nuclear magnetic resonance spectroscopy was employed to analyze the chemical structure of the compounds in the heavy oil. The results show that the majority of Huadian light shale oil is aliphatic series compounds. Among of them, n-alkanes, α-alkenes, n-alkanals and n-alcohols are of homology and all come from alkyl radicals. With the increase of final retorting temperature, length of carbon chains in light oil is shorter and there is more n-aliphatic hydrocarbons in heavy oil, because long chain aliphatic compounds were decomposed and the side chains in branched alkanes broken, while more aromatic ring condensation reactions took place which results in more aromatic rings formation in both light oil and heavy oil as well as increase of condensational degree in light oil.

    Oxygen transfer characteristics and operational performance ofrotating drum biological contactor
    LI Ning, MIAO Zhijia, LI Zaixing, WANG Zhongdong, QIN Xue, HUANG Juan
    2015, 66(7):  2678-2685.  doi:10.11949/j.issn.0438-1157.20141880
    Abstract ( 245 )   PDF (1348KB) ( 857 )  
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    A novel rotating drum biological contactor (RDBC) was operated with MBBR packing particles inside, by which anaerobic, anoxic and aerobic operating modes can be achieved by adjusting immersion level or rotating speed. The volume oxygen transfer coefficient (KLa) and power efficiency can reach 25.87 h-1 and 228.62 g·(kW·h)-1, respectively. Synthetic domestic sewage was treated with step feed post-denitrification process. The results showed that the optimal operating conditions were immersion level 2/3, rotating speed 8 r·min-1 and DO 3.0 mg·L-1 in aerobic tank, and immersion level 5/6, rotating speed 8 r·min-1 and DO 1.0 mg·L-1 in anoxic tank. In above conditions, when the influent average COD was 385.0 mg·L-1, NH4+-N 38.0 mg·L-1, TN 38.0 mg·L-1, total inflow 6 L·h-1 (HRT=18 h) and flow distribution ratio 3:1, the remove rate of effluent COD, NH4+-N and TN can reach 90.4%, 93.7% and 80.9%, respectively, which can meet the first level A discharge standards in China (GB18918—2002).

    Optimization of flow for modified step feed process treating low COD/TN municipal sewage
    WANG Wei, CHEN Qiang, WANG Chuanxin, PENG Yongzhen
    2015, 66(7):  2686-2693.  doi:10.11949/j.issn.0438-1157.20150081
    Abstract ( 207 )   PDF (696KB) ( 413 )  
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    By adjusting the distribution ratio of influent flow into anaerobic and anoxic zones, the removal efficiency of pollutants in low C/N(COD/total nitrogen)<3.5 municipal sewage using modified step feed process was analyzed. Keeping the following conditions unchanged: hydraulic retention time (HRT) 10 h, sludge retention time (SRT) 10—15 d, volume of anaerobic zone:volume of total anoxic zones:volume of total aerobic zones 4:9:9, when the actual efficiency obtained and material balance calculation results were utilized to increase gradually the water ratio distributing to the first stage i.e. anaerobic zone, the best operating conditions could be found and 4 kinds of operating conditions determined. The results show that, at given C/N ratio, concentration of nitrogen oxides in anaerobic zone does not decrease with the increase of the water ratio entered into anaerobic zone, even appears the opposite situation. The simultaneous nitrification and denitrification(SND)and microbial assimilation effect intensity play crucial role in TN removal. The rise of water ratio entered into anaerobic zone improves the removal rate of phosphate due to the phosphorus release effect of phosphorus-accumulating bacteria is enhanced in anaerobic zone. Both nitrogen and phosphorus removals as well as subsequent optimization space are considered, one of optimized water distribution ratio is 6:3:1,and at this condition, the effluent concentration of COD, ammonia nitrogen, TN, phosphate is 45.98, 0.04,17.47 and 2.43 mg·L-1 respectively.

    NO emission from burning distilled spirit lees with high contents of moisture and nitrogen in fluidized bed
    LIU Huan, CUI Lijie, ZHU Chuanqiang, ZENG Xi, GAO Shiqiu, XU Guangwen
    2015, 66(7):  2694-2701.  doi:10.11949/j.issn.0438-1157.20150182
    Abstract ( 167 )   PDF (665KB) ( 348 )  
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    This study was devoted to investigating the NO emission from combusting distilled spirit lees with high contents of moisture and nitrogen in a laboratory fluidized bed. The results showed that the NO emission increased with increasing excess air ratio and combustion temperature. The addition of extra water vapor into the combustion atmosphere for simulating the combustion of high-moisture fuel effectively decreased the NO emission, and about 46% (mass) of NO emission was reduced under appropriate conditions. In the N2-base atmosphere containing CO or H2, the metallic oxides containing in the ash of distilled spirit lees showed obvious catalytic activity on the reduction of NO, and the catalytic activity increased with increasing temperature. Water vapor in itself had not detective effect on reduction of NO, showing that its reduction of NO into N2 would be implemented through its reactions with hydrocarbons to generate reductive gases such as H2 and CO under the catalytic effect of ash.

    Numerical simulation on effect of burner tilting up angle on reheat steam temperature deviation for tangentially fired pulverized-coal boiler
    TIAN Dengfeng, FANG Qingyan, TAN Peng, ZHANG Cheng, CHEN Gang, ZHONG Lijin, ZHANG Dianping, WANG Guoqiang
    2015, 66(7):  2702-2708.  doi:10.11949/j.issn.0438-1157.20141829
    Abstract ( 240 )   PDF (1847KB) ( 465 )  
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    The burner tilting up and the bias setting of AA tilting up angle was employed in order to reduce the temperature deviation of flue gas and reheat steam. The combustion processes in a 700 MW tangentially fired boiler with different burner tilting up angles were numerically simulated. The simulated results were fitted in with the measured data well. For greater burner tilting up angle, the swirling momentum moment in the furnace and the residual swirling momentum moment in the entrance of platen zone were reduced, while the flue gas deviation in the horizontal flue gas pass was lower. The bias setting of AA burner tilting up angle can reduce the flue gas residual swirling momentum moment of the entrance of platen zone considerably and lower the deviation of the flue gas temperature and velocity. The combustion tests showed that as an effective measures to reduce the temperature deviation of flue gas and reheat steam of this boiler, the burner tilting up for 11° and the bias setting of AA tilting up angle for 10° can reduce the temperature deviation of reheat steam from 20℃ to about 4℃.

    Molecular simulations of adsorption self-assembly of SDS surfactants on nano-sized multilayer graphenes
    LIU Shuyan, CHEN Qi, WU Bin, YANG Xiaoning
    2015, 66(7):  2709-2717.  doi:10.11949/j.issn.0438-1157.20150050
    Abstract ( 311 )   PDF (7831KB) ( 938 )  
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    Molecular dynamics simulations were carried out to study the structure and morphology of SDS adsorbed on nano-sized graphene surfaces in pure water and electrolyte solution. The effects of the layer numbers of the graphene on the adsorption self-assembly structure and the buoyant density of the SDS/graphene assemblies were explored. The simulation results show that the aggregate morphology was highly dependent on the layer number of the graphene in both solutions. The stretching of surfactants to solution was enhanced with increasing layer number, leading to expansion of the self-assembly structure. In the presence of electrolyte in the solution, the surfactant micelles of SDS were transformed from the rough multi-layer to hemi-cylinder structure. In the meantime, the buoyant densities of the SDS/graphene assemblies were found to increase linearly with increasing layer number of the graphene. This behavior provided a direct theoretical basis for graphene dispersion with controlled thickness using the density gradient ultracentrifugation in the surfactant aqueous solution.

    Rheological behavior, morphology and mechanical property of poly(propylene carbonate)/thermoplastic oxidized starch composites
    JIANG Guo, XU Jinghuo, FENG Jian, HUANG Hanxiong, ZHANG Shuidong
    2015, 66(7):  2718-2724.  doi:10.11949/j.issn.0438-1157.20141682
    Abstract ( 253 )   PDF (3928KB) ( 392 )  
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    Maleic anhydride grafted poly(propylene carbonate) (PPCMA)/thermoplastic starch (TPS), PPCMA/thermoplastic oxidized starch (TPOS) and PPCMA/DL-TPOS (TPOS modified by aluminate coupling agent) composites were prepared by melt blending. Effects of starch oxidation and content of DL and DL-TPOS on rheological behavior, morphology and mechanical properties of composites were investigated. The results of Fourier Transform Infrared Spectroscopy (FTIR) revealed that the reinforcement in mechanical properties of PPC/starch composites was probably resulted from hydrogen-bonding interaction between carbonyl groups of PPC and hydroxyl groups of starch. The compatibility between PPCMA and TPOS was better than that of PPCMA and TPS. The mechanical property, storage modulus (G'), loss modulus (G'') and complex viscosity (η*) of composites were improved by oxidation of starch. Moreover, the dispersion of TPOS in PPC matrix became better when starch was modified by DL, improving the tensile strength of composites. For PPCMA/DL-TPOS composites, the tensile strength increased by 460% from 2.45 MPa to 13.72 MPa, when DL-TPOS content was from 0 to 40% (mass), while it decreased when the loading of DL-TPOS was 50% (mass). In addition, G', G'' and η* of composites was improved with increasing DL-TPOS content.

    Preparation and characterization of nanoscale humic acid-urea complex under low temperature conditions
    CHENG Liang, XU Li, HOU Cuihong, LUO Tingliang, ZHANG Baolin, LIU Guoji
    2015, 66(7):  2725-2736.  doi:10.11949/j.issn.0438-1157.20150246
    Abstract ( 112 )   PDF (2581KB) ( 462 )  
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    The nanoscale humic acid-urea complexes of 70—90 nm were prepared using nanoscale humic acid and urea as raw materials through complex reaction in order to determine their production process conditions and physical and chemical properties. The optimal process conditions of preparation nanoscale humic acid-urea complexes using response surface methodology was as follows: reaction temperature 47.6℃, reaction time 1.80 h, sodium dodecyl sulfate (as activator) concentration 50.0% (mass), solid-liquid mole ratio 9:1, concentration of complexing agent 0.14 mol·L-1 and urea dosage 200 mg. Three separate experiments were carried out in the above conditions with product yield of 90.6%±0.9%, which was agreed with the predicted yield of 91.2% by the model. The quadratic polynomial equation model of response and factor was established. The crystal form, component, morphology and specific surface area were characterized respectively by XRD, FTIR, TG, SEM, BET and so on. The results showed that the complex had perfect crystal form, high purity, uniform granularity and good dispersibility with particle size of 70—90 nm, specific surface area 189.85 m2·g-1, mean pore size 10.2 nm and pore volume 0.86 cm3·g-1, and also higher heat stability.

    Synthesis of 2,5-diaryl-1,3,4-thiadiazole corrosion inhibitors andtheir performance
    QIAN Jianhua, PAN Xiaona, ZHANG Qiang, LIU Lin
    2015, 66(7):  2737-2748.  doi:10.11949/j.issn.0438-1157.20150037
    Abstract ( 237 )   PDF (11323KB) ( 295 )  
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    Four 2,5-diaryl-1,3,4-thiadiazole compounds, namely, 2,5-diphenly-1,3,4-thiadiazole (DPTD), 2,5-di(2-hydroxyphenly)-1,3,4-thia-diazole (2-DHPTD), 2,5-di(3-hydroxyphenly)-1,3,4-thiadiazole (3-DHPTD), and 2,5-di(4-hydroxyphenly)-1,3,4-thiadiazole (4-DHPTD) were synthesized. Their corrosion-inhibiting performance in S-ethanol system was evaluated by Tafel polarization and electrochemical impedance spectroscopy (EIS). Electrochemical experimental results showed that all the thiadiazole derivatives were excellent inhibitors. The corrosion current decreased and the inhibition efficiency increased with increasing concentrations of the inhibitors. The optimum concentration was 90 mg·L-1, while the inhibition efficiency of DPTD, 2-DHPTD, 3-DHPTD and 4-DHPTD was 85.8%, 94.6%, 96.4% and 97.1%, respectively. Scanning electronic microscope (SEM) and atom force microscope (AFM) were also carried out, and confirmed the existence of the adsorbed film which was prevailed in addition of thiadiazole derivatives. The adsorption of these compounds onto silver surface from 50 mg·L-1 S-ethanol was followed the Langmuir adsorption isotherm and attributed to mixed-type adsorption mainly dominated by chemisorption. Quantum chemical calculations and molecular dynamic simulations also demonstrated that thiadiazole derivatives were good inhibitors. The experimental results showed that the order of inhibition efficiency was [4-DHPDT]> [3-DHPDT]> [2-DHPDT]> [DPDT], which was agreed with the theoretic method.

    Influence of ignition position on overpressure of premixedmethane-air deflagration
    ZHENG Ligang, LÜ Xianshu, ZHENG Kai, YU Minggao, PAN Rongkun, ZHANG Yugui
    2015, 66(7):  2749-2756.  doi:10.11949/j.issn.0438-1157.20141789
    Abstract ( 290 )   PDF (1915KB) ( 445 )  
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    The premixed stoichiometric methane-air deflagration is conducted in a transparent square cross-section duct. Effects of the ignition positions on the overpressure characteristics of the premixed methane-air deflagration flame propagating in the duct closed at one end and open at the opposite end are obtained. The experimental results show that the pressure waveform changes from no oscillation to weak oscillation with the equiamplitude then to sharp oscillation with the exponential increase amplitude as the ignition positions relative to the closed end of the duct are increased. The generation mechanism of the overpressure is closely dependent on the transient flame structures and the overpressure extrema of the oscillating waveforms always correspond to the flame position extrema. The oscillation periods of the overpressure waveforms during the phase of the exponential increase amplitude are linearly decreased with the time since ignition and well correlated with the length of the unburnt gas column. The oscillation is triggered by the venting of the flame front located at the open end of the duct, and then amplified by the flame-sound interaction in the unburnt gas column between the pressure wave and the flame front located at the closed end of the duct.