CIESC Journal

Calculation of partial molar volume of components in supercritical ammonia synthesis system

WANG Cunwen, YU Chuanbo, CHEN Wen, WANG Weiguo, WU Yuanxin, ZHANG Junfeng

2006, 57(7): 1503-1507.

Abstract ( 687 )

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The partial molar volumes of components in a supercritical ammonia synthesis system were calculated under different conditions with the calculation formula of partial molar volume derived from R-K equation of state.The objectives were to comprehend phase behavior of components and to provide the theoretical explanation and guidance for developing novel processes of ammonia synthesis under supercritical conditions. The conditions of calculation were H₂/N₂=3, concentration of NH₃ in synthesis gas ranging from 2% to 15%, concentration of medium in supercritical ammonia synthesis system ranging from 20% to 50%,temperature ranging from 243 K to 699 K and pressure ranging from 0.1 MPa to 187 MPa.The results showed that the ammonia synthesis system could reach supercritical state by adding a suitable supercritical medium and then controlling the reaction conditions.It was good for supercritical ammonia synthesis that medium reached supercritical state under the corresponding total pressure and composition,and at a temperature near the normal temperature or near the critical temperature of medium or in the range of temperature of commercial ammonia synthesis.

New correlation for binary interaction parameters of paraffins mixtures

CHEN Jian, HUANG Zhiming, BAO Yongzhong, WENG Zhixue

2006, 57(7): 1508-1512.

Abstract ( 673 )

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Based on the Mie potential function theory and London dispersion forces theory, and with the introduction of Leland’s molecular shape factors to modify the inadequacy of the two parameters corresponding states principle for complex fluids, a new correlation for binary interaction parameters of the equation of state was proposed.The pseudocritical rules of Joffee and Stewart were introduced to evaluate the molecular shape factors of mixtures in the deduction process.When Mie potential constant was set to be 3, the new correlation obtained could be used to evaluate the binary interaction parameters of paraffins mixture without back-calculation.The new correlation showed that besides the critical properties of components in paraffins mixture,the binary interaction parameters were the function of composition, temperature, molar volume, acentric factor and component’s ionization potential.Satisfying results with the maximum average absolute error of 2.40%, were achieved when the correlation was used in the Peng-Robinson equation of state to calculate the critical pressure of paraffins mixture.

A modified model of diffusion coefficient in polymer-solvent systems based on Simha-Somcynsky equation-of-state

LV Hongling, WANG Baoguo, YANG Jichu

2006, 57(7): 1513-1517.

Abstract ( 619 )

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A modified diffusion model for polymer-solvent systems was proposed by introducing the Simha-Somcynsky（SS）equation-of-state（EOS）into the Vrentas-Duda free-volume model.The complex process of viscoelastic measurements in the Vrentas-Duda model was avoided successfully，since the effective free volume of a polymer can be estimated from the SS EOS together with the Williams-Landel-Ferry（WLF）fractional free volume.Calculated diffusion coefficients of benzene，toluene，ethylbenzene and chloroform in polystyrene，polyisobutylene and poly（vinyl acetate）indicated that predictions from the modified model were consistent with experimental values，and the accuracy was better than those from the Vrentas-Duda model for predicting solvent self-diffusion coefficients.Moreover，the modified model can reflect the effect of pressure on diffusion coefficients.Solvent diffusion coefficients in polymers decrease with increasing pressure.Especially in dilute polymer-solvent systems，diffusion coefficients change by several orders of magnitude with increasing pressure.With the increase of solvent concentration，diffusion coefficients gradually approach those values under atmospheric pressure，thus the effect of pressure can be neglected reasonably.

Analysis of entropy generation in falling film evaporation

CHEN Xi, WANG Jianjun, ZHU Jiahua, SHUAI Jianyun, FENG Zhaohua

2006, 57(7): 1518-1524.

Abstract ( 771 )

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Based on the second law of thermodynamics for an open system under non-equilibrium state an intensive analysis of the entropy generation in the process of falling film evaporation was made.A quantitative correlation was deduced to calculate the unit entropy generation number,N_s from the traditional Reynolds number and other parameters under the condition of Re>1450(c_pμ/λ)-1.06(0.5-0.25ω)^-1.It was unveiled that N_s decreased with decreasing thickness of the falling film and increased after the optimal ω, which corresponded with a minimum value of N_s.The good agreement between the expressions of correlation and the results obtained from an experimental rig of falling film evaporation for phosphoric acid concentration in a vertical heated tube with the dimension of φ30×2×6000 demonstrated that the correlation equation could be rationally used to predict the entropy generation in falling film evaporation.This theoretical prediction, calculated from ordinary thermal process parameters is useful in enhancement of thermodynamic efficiency in industrial processes.

Optimal designing of cracking tower for waste tires based on heat and mass transfer model （Ⅰ）Model development

LIU Baoqing, JIANG Jialing

2006, 57(7): 1525-1531.

Abstract ( 574 )

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A new vertical cracking tower with multiple hollow disks was developed, which could pyrolyze waste tires into carbon black, liquid oil and fuel gas.Based on the assumptions of annular granular heap, constant angle of repose and uniform physical properties, a mass transfer model in the cracking tower for waste tires was presented.The equations for calculating several important parameters, such as height and volume of each granular heap, retention time, effective covering ratio, critical capacity were provided along with the new mass transfer model.According to the penetration model of particle heat transfer and kinetic model of tire pyrolysis, the exit temperature and rubber remnant content in granular heaps were effectively predicted by a straightforward stepwise calculation procedure, and the maximum pyrolysis capacity was predicted as well.The theoretical results predicted with the heat and mass transfer model were in satisfactory agreement with experimental data from a 3000 t•a^-1 pilot-plant.

Optimal designing of cracking tower for waste tires based on heat and mass transfer model（Ⅱ） Optimal designing

LIU Baoqing;JIANG Jialing

2006, 57(7): 1532-1536.

Abstract ( 568 )

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In order to achieve maximum effective heat transfer area and heat transfer coefficient, some important parameters of a new cracking tower with multiple hollow disks were optimized on the basis of heat-mass transfer model developed in Part（Ⅰ）, including the area overlapping ratio, rotating speed of axis, plow-setting coefficient, number and setting angle of plows, distance between plows.It was shown that the area-overlapping ratio was better in the interval of 0 to ξ_c.A higher rotating speed of axis was preferred provided that the quality of pyrolysis products was not affected.Multiple plows system was recommended in the design of a new cracking tower for waste tires.The distance between plows was optimal when the critical capacity values of all annular granular heaps were equal.The setting angle of 45° was helpful to decrease the drag force acting on plow and enhance mixing of granular heaps.

Compressible flow analysis of filling stage in plastic injection molding

SHEN Changyu, WANG Lixia, LI Qian, CHEN Jingbo, LIU Chuntai

2006, 57(7): 1537-1542.

Abstract ( 563 )

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The flow and heat transfer of the melt in cavity have crucial effects on the final quality and properties of injection-molded parts.In order to predict the shrinkage, warpage and mechanical properties of the injection molded parts, it is necessary to predict the history of flow and heat transfer of melt accurately during the molding process.In this paper, the modeling of filling stage is based on the generalized Hele-Shaw flow of a compressible viscous fluid under non-isothermal conditions with consideration of the effects of compressibility and phase change.A hybrid FEM/FDM was employed to calculate the pressure field and temperature field, and the control volume method was adopted to advance the melt front.The compressible flow analysis of filling stage in plastics injection molding was implemented by using Visual C++.In order to keep each energy term be continuous across inter-element boundaries, each item of energy equation was discretized at the centroid of the elements, and then the energy equation at each vertex node was obtained by a weighted averaging scheme, thus the temperature field was estimated by solving the integrated energy equation of the whole calculation domain.Two parts were analyzed, and the comparison of numerical and experimental results verified the numerical algorithm and program of the compressible filling simulation.The numerical results also indicated that the compressibility of the material had important effects on the flow field of imbalance molds.

LDV measurements of flow field in a unit of structured packing

LIU Chunjiang, LI Yingke, HUANG Ying, CHEN Jiangbo, YUAN Xigang, YU Guocong

2006, 57(7): 1543-1547.

Abstract ( 683 )

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It has long been recognized that the flow pattern，especially the velocity distribution of the fluid，is of great importance in determining the performance of the equipment using structured packing as its internals.By using three-dimensional laser Doppler velocimetry（LDV），the liquid velocity distribution of the glycerol aqueous solution was measured in a typical unit of structured packing（Mellapak 350Y）.Time averaged three-dimensional velocity distributions of the unit were measured at different flow rates.The experimental data showed that the liquid velocity profile of the single phase flow was complex because of the special geometry of the unit of structured packing.In the central region of the unit，the liquid was mixed strongly and re-distributed.It was the main cause generating the vortexes and secondary flow.

Numerical simulation of flow field and heat transfer within a vortex tube

ZHOU Shaowei, JIANG Renqiu, SONG Fuyuan, ZHANG Peng, WANG Pengtao, CAI Jie

2006, 57(7): 1548-1552.

Abstract ( 690 )

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Despite the simplicity of the vortex tube’s geometry，the fundamental mechanism underlying the energy separation effect is still elusive due in part to the complexity of flow behavior inside the tube.In order to investigate its fundamental mechanism，a three-dimensional simulation was performed to predict the flow field and temperature distribution within a vortex tube.The results demonstrated that the large pressure gradient in the radial and axial directions was the main reason for the separation of hot and cool flow.Radial centrifugal force led to different static pressures at different positions along the axis.Inner flow experienced an adiabatic expansion process while peripheral flow experienced an adiabatic compression process.Due to gradient distribution of static temperature from axial center to periphery at different positions along the axis and re-circulating flow，heat trasfer and mass transfer occurred between inner and peripheral flow.Meanwhile，the numerical data and experimental results were compared and good agreement was obtained.

Multi-scale and multi-fractal characteristics of pressure signals in SCISR

ZHANG Jianwei;JIAO Li

2006, 57(7): 1553-1559.

Abstract ( 547 )

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The complexity of pressure fluctuation dynamics in submerged circulative impinging stream reactor (SCISR) with different rotating speeds was studied by using the multi-scale and R/S analysis method.The Daubechies second order wavelet was firstly used to decompose pressure signals at different rotative speeds to 1—9 scale detail signals and scale approximation signals.Then, Hurst analysis was used to analyze multi-fractal characteristics of different scale signals.By analyzing the signal profile of different scales, different fractal structures at different scales were found, and there remained the similar trend with increasing rotating speed.Besides, there were some deterministic non-periodic components in the system and similar energy exchange between particles caused the diffusion of turbulence, which was the characteristic of an open system.The vortex with different scales would cause chaos.

Multi-scale analysis of acoustic emissions and malfunction diagnosis in gas-solid fluidized bed

WANG Jingdai;JIANG Binbo;YANG Yongrong;SHU Weijie

2006, 57(7): 1560-1564.

Abstract ( 768 )

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Agglomerations could be detected in a fluidized bed by utilizing wavelet analysis, on the basis of the mechanism that AE signals with different frequencies were emitted when the particles with different sizes impacted the wall.The acoustic signals of particles were investigated in an externally heated fluidized bed φ100 in diameter and in a pilot-scale industrial fluidized bed φ420 in diameter respectively.In those experiments, the number of small particles decreased obviously while the number of large particles increased due to agglomeration.The signals were decomposed by multi-scale wavelet analysis.While the acoustic energy ratio increased from low scale to high scale layer by layer, the main frequency of acoustic signals transferred from high frequency to low frequency.Meanwhile, the d6th, d7th scales, which represented large size particles, increased suddenly,indicating the occurrence of agglomerations.Thus, the agglomerations in fluidized bed could be quickly and exactly detected online by the acoustic emission technique.

Modeling of liquid circulation in gas-liquid bubble columns

LUO Xiao;LIU Pingle;LUO He’an

2006, 57(7): 1565-1569.

Abstract ( 557 )

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This paper proposes a modified model of eddy viscosity distribution for liquid flow in bubble columns based on a relationship from single-phase flow and then develops a liquid circulation model for bubble columns.The comparison between the liquid circulation model and the reported experimental data shows that the liquid circulation model based on the modified model of eddy viscosity distribution not only agrees with the data very well but also has a wide application range.In addition, the determination of the model parameters is discussed according to the simulation for the reported data with this model.

Preparation of lanthanum and carbon co-doped TiO₂ and photocatalysis under visible irradiation

SUN Hongqi;CHENG Youping;JIN Wanqin;XU Nanping

2006, 57(7): 1570-1574.

Abstract ( 618 )

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TiO₂-based photocatalysis technology was developed and applied to photodegradation of organic contaminants by utilizing solar energy effectively.Pure and doped or co-doped TiO₂ catalysts with various amounts of lanthanum and carbon were obtained by a modified sol-gel process, in which tetrabutyl titanate was used as precursor and lanthanum nitrate, tetrabutylammonium hydroxide as ion donors.The as-prepared photocatalysts were found to be of anatase phase, higher specific area, and visible response by means of XRD, BET and UV-vis spectra analysis.The co-doped TiO₂ catalysts showed higher photocatalytic activity in degradation of rhodamine B, methyl orange and 4-chlorphenol under Xe lamp, sunlight or daylight irradiation than that of pure and single doped ones.Photodegradation experiments showed that the co-doped catalyst with 0.5% (molar ratio) lanthanum calcinated at 500℃ was of the highest catalytic efficiency under visible irradiation.The higher visible light photocatalytic activity of co-doped TiO₂ was attributed to the doped carbon that lowered the ban

Relationship between photocatalytic degradation of formic acid and formation of hydrogen peroxide

HUA Zhaozhe, CHEN Jian, Shiraishi Fumihide, Nakasako Tsugunori, WANG Xinpeng

2006, 57(7): 1575-1581.

Abstract ( 688 )

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The formation of H₂O₂ in the decomposition of HCOOH in water with TiO₂ or Pd/TiO₂ as catalyst under irradiation with one of the three types of UV lamps（blacklight blue fluorescent lamp, BL;germicidal lamp,GL;ozone lamp，OL）was investigated.Irradiation with UV light from the BL synthesized H₂O₂ from water in the presence of the photocatalyst.Similarly，irradiation with UV light from the BL or GL decomposed HCOOH in the presence of the photocatalyst.Under irradiation with every light source，HCOOH was decomposed more quickly with Pd/TiO₂ than with TiO₂.The rate of decomposition of HCOOH was large and in decreasing order of OL，GL and BL.The rate and amount of H₂O₂ formed were also large and in the same order.The result showed that the initial rate of decomposition of HCOOH was directly proportional to the initial rate of formation of H₂O₂，indicating that the photocatalytic activity was strongly dependent on the capability of the photocatalyst to form H₂O₂.

Polymerization of methyl methacrylate/acrylic acid/water soap-free inverse microemulsions

LI Xiao;XIA Shengping;ZHANG Weiying;XIAO Xianhua;REN Wencheng;DONG Shengxiong

2006, 57(7): 1582-1587.

Abstract ( 632 )

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The ternary phase diagram of methyl methacrylate (MMA)/acrylic acid (AA)/water soap-free microemulsion system was figured out by the conventional titration technique, and the domains of different types of single phase microemulsions were partitioned with conductivity measurement.Based on the phase diagram, the influence of the amount of initiator (AIBN), the contents of AA and water on the rate of polymerization in MMA/AA/H2O soap-free inverse microemulsions was investigated.The results showed that polymerization rate increased with increasing amount of initiator or increasing content of AA and there appeared a peak value of rate with increasing content of water.The kinetic relation was obtained, which indicated that AA was an effective emulsifier to enforce and hasten polymerization in dispersed droplets at the same time with conventional polymerization in the continuous phase.In addition, the morphology of the products from soap-free microemulsion was observed under an environment scanning electron microscope and the existence of microporous structure was found.

Electro-oxidation of oxalic acid with polypyrrole prepared in 1-ethylimidazolium trifluoroacetate

LI Meichao, SHEN Zhenlu, MA Chun’an, GAO Yunfang

2006, 57(7): 1588-1590.

Abstract ( 999 )

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The electrochemical oxidation of oxalic acid is important in environmental engineering.In this paper，polypyrrole（PPy）was prepared galvanostatically in an ionic liquid 1-ethylimidazolium trifluoroacetate（HEImTfa）and its electro-catalysis function for the electrochemical oxidation of oxalic acid was investigated by using cyclic voltammetry.The results showed that the electro-catalytic activity of PPy prepared in HEImTfa（PPy-HEImTfa）was greatly improved as compared with that prepared in conventional H₂SO₄ aqueous solution.Therefore，the use of HEImTfa as growth electrolyte and solvent for electro-polymerization of pyrrole resulted in an electrochemically catalytic film of PPy for the electro-oxidation of oxalic acid.

Synthesis of thermally coupled complex distillation system based on stochastic optimization (Ⅰ) Problem formulation

AN Weizhong;YUAN Xigang

2006, 57(7): 1591-1598.

Abstract ( 646 )

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Based on stochastic optimization strategy, a formulation methodology was proposed for optimal synthesis of thermally coupled complex distillation column systems comprising simple columns, complex columns with side rectifier and/or side stripper as well as partially or fully thermally coupled (Petlyuk) columns with prefractionators.To cope with the uncertainty of the number of column sections and thermally coupled streams for a given multi-component mixture separation problem, a decomposition strategy was proposed so that the original problem could be divided into a series of subproblems with different numbers of column sections.To represent and manipulate the flowsheet structure in the optimization, a coding procedure was developed.The procedure was implemented by tearing the representation into two strings of code: separation sequence and thermal-coupling scheme.The flowsheet structure encoding was performed by adopting a binary sort tree approach that is originally used in data structure theory, so that the problem formulation and solution becomes tractable.Finally, taking the recoveries of key components in the pretractionators and reflux ratios as continuous variables, a conceptual mixed-integer nonlinear programming (MINLP) problem was formulated.The solution to the problem could be achieved with an improved simulated annealing algorithm.

Synthesis of thermally coupled complex distillation system based on stochastic optimization(Ⅱ)Example illustration and analysis

AN Weizhong;YUAN Xigang

2006, 57(7): 1599-1604.

Abstract ( 570 )

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By applying the method developed in part (Ⅰ) of this paper series for the formulation and solution of the problems of synthesis of thermally coupled complex distillation system, three example problems for five-component mixtures separation were solved to illustrate the implementation and effectiveness of the proposed procedure.In each case, six sub-schemes were solved respectively.The optimized parametes and economic benefits of different optima scenarios were analyzed and compared.Some preliminary insights into the rules for synthesis and design of multi-component thermally coupled complex distillation systems were presented as well.

Lumped kinetics model and its on-line application to commercial catalytic naphtha reforming process

HOU Weifeng;SU Hongye;HU Yongyou;CHU Jian

2006, 57(7): 1605-1611.

Abstract ( 697 )

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Based on the lumping theory and the reaction network with seventeen lumped components reported earlier, a new kinetic model involving twenty lumped components and thirty-one reactions was developed for catalytic reforming process.The subdivision of 8-carbon aromatics and all the hydrocracking reactions of the paraffin lumps were considered in this model.The 20-lumped kinetics model was used to simulate commercial continuous catalytic reforming (CCR) unit.Fair agreement between the calculated and operating data was obtained and the simulation precision of cracking products by the 20-lumped kinetics model was better than that by the 17-lumped model.By adopting an on-line prediction and correction strategy, the 20-lumped model was also used to on-line calculate aromatics yield, yield of each aromatics lump, and RON (octane number of reformate) of the CCR process.The trend and precision of on-line prediction were very good.The average deviations between on-line predicted and actual aromatics yield and RON were 0.52%(mass) and 0.36 respectively,nearly equivalent to the off-line prediction performance.

Application of least squares support vector machine within evidence framework in PTA process

ZHENG Xiaoxia;QIAN Feng

2006, 57(7): 1612-1616.

Abstract ( 688 )

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Support vector machine（SVM）is a new learning machine based on the statistical learning theory.A regression algorithm based on least squares vector machine（LS-SVM）within the Bayesian evidence framework was proposed by considering the noise parameter β.Within the evidence framework，the regularization and kernel parameters could be adjusted automatically，to achieve a better tradeoff between the minimum error and model’s complexity.The proposed method was applied to predict the concentration of 4-carboxybenzaldhyde（4-CBA）in an industrial purified terephthalic acid（PTA）oxidation process.The estimated outputs of LS-SVM match the real values and followed the change of the 4-CBA content very well.The results show that the proposed method provides a new and effective method for on-line 4-CBA prediction.

Activated carbon electrodes optimization

LI Shengjuan;WANG Shulin;XU Bo;CHEN Xinlong

2006, 57(7): 1617-1621.

Abstract ( 645 )

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In the present study，the commercial activated carbon(AC) as electrode material used by electric double-layer capacitor(EDLC) were modified through physical method.The experiment was carried out in a vibration mill.The resultant activated carbon was characterized by BET surface area, pore size, pore volume and electrochemical performance.BET surface area increased from 1739.77 m²•g^-1 to 2215.40 m²•g^-1 after modification,micro-pore surface and mesopore increased 22% and 35% respectively and pore volume increased by 20%—30%.Both high pore volume and more rational pore distribution of active carbon contributed to better electrochemical characteristics.The modified activated carbon increased the specific capacitance of electrode by 10%, up to 424 F•g^-1.

Formation of aluminum corrosion sensitive film on optical fiber and its corrosion performance

QIU Zhigang;LUO Ya’nan;SONG Shizhe

2006, 57(7): 1622-1625.

Abstract ( 716 )

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In this paper, with the technology of vacuum sputter, pure aluminum corrosion sensitive film was directly deposited on the core of optical fiber with its clad removed.Metallographic microscope and scanning electron microscope (SEM) were used to analyze the structure of the film.The thickness of the pure aluminum corrosion sensitive film was about 14.65 μm, and the film was distributed evenly and firmly bonded with the fiber core.Galvanostatic step and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion resistance in NaCl solution with different concentrations (0.001—0.1 mol•L^-1).The result showed that the corrosion resistance of the aluminum film was similar to that of industrial pure aluminum in NaCl solution with the concentration less than 0.1 mol•L^-1.But the EIS data showed that there were holes on the film surface.

Leakage model of contacting mechanical seal based on fractal geometry theory

SUN Jianjun;GU Boqin;WEI Long

2006, 57(7): 1626-1631.

Abstract ( 939 )

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The existing leakage models，which include smooth plane leakage model，rough and waveform surface leakage model，and tapered-face leakage model，can not be applied to describing the active state of contacting mechanical seal.In these models，only prime microscopic surface topography and constant leakage rate are taken into consideration.Based on fractal geometry theory，a leakage model was established with consideration of the change of microscopic surface topography and time-correlation of leakage rate.The relationship between leakage rate，the change of microscopic surface topography of seal surface and leaking channel under operation conditions was described quantitatively by fractal parameter with unattached dimension.There existed an optimum fractal parameter during the mechanical seal running，which corresponded to the lowest leakage rate.The research results helped to ascertain the roughness and waviness of seal surface，and to select machining methods of sealing members.According to the leakage model presented in this paper，the leakage rate of contacting mechanical seal can be forecasted，which may be used as reference in the maintenance and operation of mechanical seals.

Estimation and control of yield of cephalosporin C separated from fermentation broths by ceramic membrane

WANG Longyao, XING Weihong, YANG Gang, XU Nanping

2006, 57(7): 1632-1636.

Abstract ( 581 )

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This paper is concerned with estimation and control of the yield in the process of clarifying fermentation broths for the production of cephalosporin C by ceramic membrane.Three parameters (volume concentration ratio in pre-concentration step, a; volume dilution ratio in diafiltration step, b; volume concentration ratio in post-concentration step, c) are introduced in the model to estimate the yield of cephalosporin C.The equations for estimating overall yield and the piecewise functions for estimating real-time yield are put forward.The yields are compared with the operation modes of continuous feed diafiltration (CFD) and intermittent feed diafiltration (IFD) by model calculation and experiment.The results show that the model is helpful for optimizing the microfiltration process by enhancing the yield and reducing the overall operation time.By using the model in this paper, the yield of cephalosporin C can be controlled effectively in the process of membrane filtration.

Influence of cell homogenization on interactions between biomass and adsorbent in expanded bed ion-exchange adsorption

DONG Jiannan;LIN Dongqiang;YAO Shanjing

2006, 57(7): 1637-1642.

Abstract ( 619 )

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For ion-exchange expanded bed adsorption, the biomass (cells and cell debris) existing in the feedstock would adhere to the adsorbent, which certainly influence the bed stability and adsorption efficiency for the targets.With E.coli DH5α as the model biomass and Streamline DEAE as the typical anion exchanger for EBA, the influence of cell homogenization processes on the biomass/adsorbent interaction in expanded bed was investigated by using the biomass pulse-response experiments.The biomass transmission index (BTI) was used as a quantitative parameter for evaluating the biomass adsorption in expanded bed.The results indicated that more intense homogenization caused higher BTI and weaker biomass/adsorbent interaction, with smaller size of cell debris and lower zeta potential of homogenate.Based on the theory of electrostatic interactions, a good linear correlation was found between BTI and (-ζ_Aζ_Bd_B), which combined the influences of zeta potential of adsorbent (ζ_A), zeta potential of biomass (ζ_B) and biomass size (d_B).When -ζ_Aζ_Bd_B<100 mV²•μm, BTI response was more than 0.9, indicating no or very slight biomass/adsorbent interactions.This relation could be used to pre-evaluate the influence of biomasss and simplify the process design of EBA.

Effects of temperature and its profile on purification performance of biotrickling bed for waste gas treatment

LIAO Qiang;TIAN Xin;ZHU Xun

2006, 57(7): 1643-1648.

Abstract ( 659 )

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The effect of temperature on the purification performance of trickling biofilter for treating toluene waste gas was investigated experimentally.The results showed that temperature in trickling biofilter bed had a significant influence on purification efficiency.As the inlet temperature of circulation water increased from 10℃ to 60℃, the purification efficiency of trickling bed had a maximum value corresponding to a temperature within 30—40℃.For verifying the effect of temperature on purification efficiency, the experiments for the activity of toluene dioxygenase were conducted at various temperatures of culture fluid.The results of enzyme activity experiment showed that ambient temperature had a great effect on the microorganism enzyme activity for toluene degradation.There existed a maximum enzyme activity at the culture fluid temperature of 30℃, which was coincident with the purification experiment.The temperature profile in the packed bed of trickling biofilter was also measured in the experiments.Under co-current operation mode,the temperature of trickling biofilter bed increased gradually in gas and liquid flow directions which indicated that the metabolic biodegradation of the organic pollutants was an exothermic process.The temperature rise between the outlet and the inlet of trickling biofilter increased as the circulation liquid flow rate decreased and that of waste gas increased.A higher inlet toluene concentration led to a higher temperature rise.Meanwhile, it was also found that the operation mode had a significant effect on temperature profile in the trickling biofilter.

Characteristics of poly（vinyl alcohol）degradation bacterium Xanthomonas sp.

ZHANG Xing;DU Guocheng;CHEN Jian

2006, 57(7): 1649-1654.

Abstract ( 742 )

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A bacterium，isolated from putrified poly(vinyl alcohol)(PVA) gum，could degrade completely poly（vinyl alcohol）.It belongs to the genus of Xanthomonas and needs complex organic nitrogen for growth.The biodegradation rate of PVA was increased by addition of beef extract and peptone F403，in which peptone had more influence on PVA degradation.The bacterium could adapt to a broad pH range for PVA degradation.The polymerization degree of PVA did not show any significant influence on PVA biodegradation rate.The results of resting cells culture showed that PVA was firstly adsorbed and then degraded by the cells.1 g•L^-1 of PVA could be completely degraded as expressed with TOC by 1 g•L^-1 of resting cells after 52 h cultivation.However it was difficult to determine the activity values of PVA oxidase，dehydrogenase and total degrading enzyme in this strain.

Mathematical modeling of Zoogloea sp.batch fermentation for PHAs synthesis

YANG Jinshui; HUANG Jianxin

2006, 57(7): 1655-1658.

Abstract ( 572 )

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A mathematical model that described the strains growth, product formation and medium consumption was presented to predict the performance of batch fermentation of Zoogloea sp.GY3 which was screened from activated sludge and could synthesize PHAs.A simple model was proposed by using the Logistic equation for growth, the Luedeking-Piret equation for PHAs production and the Luedeking-Piret-like equation for sucrose consumption.The model appeared to provide a reasonable description for each parameter during the growth phase.The production of PHAs was growth-associated.The models were in good agreement with the measured data in experiments.

Effects of activated carbon surface chemistry and pore structure on adsorption of HAAs from water

WANG Kunping;ZHANG Yu;QI Rong;YANG Min; DENG Rongsen

2006, 57(7): 1659-1663.

Abstract ( 710 )

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To improve the adsorption performance of polar，hydrophilic haloacetic acids（HAAs）on non-polar，hydrophobic activated carbon，the surface properties and HAAs adsorption ability of several activated carbons of different origins were characterized with N₂ adsorption and X-ray photoelectron spectroscopy and HAAs isothermal adsorption experiments, and the relationship between the surface chemistry characteristics and the adsorption ability of HAAs onto activated carbon was investigated.It was found that the adsorption capacity was influenced by the properties and contents of the surface chemical group.The adsorption capacity was higher with a lower oxo-group content.

Physiochemical characteristics and formation mechanism of inhalable particulate matter in coal combustion process

SUI Jiancai, XU Minghou, QIU Jihua, YU Yun, XIA Yongjun, GAO Xiangpeng

2006, 57(7): 1664-1670.

Abstract ( 591 )

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By using low pressure impactor, fly ash was sampled at the inlet and outlet of ESP in 50 MW and 100 MW utility boilers separately.The composition, mass size distribution and microstructure of fly ash were measured by using X-ray fluorescence,0.001 mg precision microbalance and scanning electron microscope (SEM).A similar bimodal distribution of PM₁₀ was obtained in both boilers studied, the small and large modes were formed at 0.1 μm and 4 μm, respectively.The chemical composition of the size-segregated ash showed that the ash particles smaller than 0.377 μm were formed via nucleation of vaporized ash components, and the primary chemical components were the oxides and sulfates of alkali metal and alkali earth metal in submicron-size ash.The microstructure measurements showed that the supermicron-size ash was formed by coagulation and coalescence of the submicron-size ash,and fragmentation and coalescence of mineral matter.Refractory oxides were the major composition of supermicron-size ash.

Mixing and transport of partcles in rotating cone

HU Guoxin;CHEN Hongwen;GONG Xiwu

2006, 57(7): 1671-1676.

Abstract ( 640 )

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An experimental apparatus was set up to investigate the particles mixing and transport in a rotating cone.The effects of cone rotational frequency，feed rate and the cross section of overflow gate on the hold-up and residence time of particles in the cone were examined for different conditions.The results showed that it was absolutely possible for the rotating cone to control particles transport and ensure a suitable residence time of particles simultaneously by proper structural design and operational means.The erected ring wall could prolong the residence time of particles in the cone.The blender was important to particles mixing and transport in the rotating cone.The particle hold-up in the rotating cone tended to increase with the increase of feed rate and with the decrease of cone rotational frequency.The residence time was inversely proportional to feed rate and cone rotational frequency.The increase of the overflow gate cross section tended to reduce hold-up and the residence time of particles in the rotating cone.

High pressure hydrogen storage in hollow glass microspheres

ZHANG Zhanwen;TANG Yongjian;WANG Chaoyang;LI Bo;QI Xiaobo

2006, 57(7): 1677-1681.

Abstract ( 535 )

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High strength hollow glass microspheres with diameter no more than 1 mm are attractive for hydrogen storage and transport.Microspheres were made by drop tower techniques with 150—250 μm diameter and 0.9—4.0 μm membrane thickness.By immersion in high pressure hydrogen for a period of time at an elevated temperature the microspheres could be filled with hydrogen.The hydrogen pressure was equal to that of gas-filled chamber at 350℃ for 6—10 h.With the help of Fick〖DK〗’s first law and the ideal gas law the pressure in the microsphere could be calculated.Based on the Arrhenius expression,permeability coefficient decreased as temperature dropped.The half-life time for hydrogen retention in hollow glass microspheres was about 40—50 d at room temperature.The maximum hydrogen pressure could reach 20—25 MPa in the hollow glass microspheres with 200 μm

Simulation of bimodal polyethylene products by operation parameters oscillation

WANG Jingdai;PU Yajun;YANG Yongrong

2006, 57(7): 1682-1688.

Abstract ( 757 )

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For the industrial fluidized bed gas-phase polyethylene production process, a new technology that produces bimodal polyethylene in a single reactor by oscillating the operation parameters was proposed.The change of molecular weight distribution during oscillation of operation parameters, including hydrogen flow rate, ethylene flow rate, comonomer flow rate and reaction temperature was investigated by simulation.After oscillating the operation parameters, the bimodal molecular weight distribution (MWD) of polyethylene was generated.The simulation results show that it is feasible to produce bimodal polyethylene in a single reactor by oscillating the operation parameters.The simulation result also shows that oscillating hydrogen flow rate is the most effective method to produce bimodal polyethylene.

Reactivity and property of phenolic resin synthesized by phenol and paraformaldehyde

MA Junjie;CHENG Jue;YANG Wantai

2006, 57(7): 1689-1693.

Abstract ( 658 )

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Phenolic resin is considered to be the first commercialized synthetic resin and is widely used in industry.But a convenient and quantitative method for monitoring the structure of phenolic resin has seldom been proposed.In this paper，the expandable phenolic resin was synthesized by paraformaldehyde and phenol in the presence of aqueous NaOH.The gelation time and the CH₂OH index measured by FT-IR spectrometer were employed respectively to investigate the reactivity of the synthesized expandable phenolic resins.The experimental results showed that the two analytical methods were very effective in tracing and differentiating the variation in reactivity of resins during the process of phenolic resin synthesis，and the analytical results agreed with each other.The effect of reaction time on the reactivity，viscosity and solid contents of the phenolic resins and further on the preparation of the expandable phenolic resins was investigated.

Preparation of PLA microparticles by ASES technique

YU Wenli;ZHAO Yaping;ZHANG Hejun

2006, 57(7): 1694-1698.

Abstract ( 644 )

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Poly lactic acid(PLA) microparticles were prepared by a supercritical fluid method, called the aerosol solvent extraction system method.The effects of pressure, temperature, PLA solution concentration and its flow rates,and PLA molecular weight (Mw) on the morphology and particle size (PS) of the resulting PLA microparticles were investigated.The results showed that a viscous film was found at sinter filter fixed on the bottom of the precipitator when Mw was 100000, or PLA solution concentration was 1 g•ml^-1, when Mw was less than 100000 or PLA solution concentration was smaller than 1 g•ml^-1, PLA microparticles were produced.In the scope of study here, pressure and temperature were the most significant factors on PS, and increasing pressure, or decreasing temperature could lead to a significant decrease in PS.At 20 MPa，35℃，PLA flow rate 240 ml•h^-1，concention 0.1 g•ml^-1,M_w=10000, the PLA microparticles with a PS of 200～600 nm were successfully obtained.XRD suggested that there was no significant change in crystalline type, but significant decrease in the crystallinity of the resulting PLA products was observed.

Preparation of hexagonal plate nano-aluminum trihydrate by hypergravity-carbonation

WANG Ziyun;SHAO Lei;GUO Fen;CHEN Jianfeng;ZHAO Ruihong;WANG Dongguang

2006, 57(7): 1699-1703.

Abstract ( 606 )

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Nanosized aluminum hydroxide was prepared by carbonation in a hypergravity rotating packed bed（RPB）reactor using sodium meta-aluminate and carbon dioxide as source materials.Characterization of XRD，TEM，TG-DSC and particle size distribution indicated that the as-prepared product was bayerite with hexagonal-plate shape and particle size of less than 100 nm，which also exhibited uniform morphology，narrow particle size distribution and good dispersibility.The optimum synthesis conditions were obtained.The experimental results showed that the preparation of hexagonal-plate-shaped aluminum hydroxide by RPB is technically feasible due to its simplicity and reproducibility.

Preparation, characterization and dielectric properties of solid solution Ca_1-xSr_xZrO₃

LEI Jixia;LIU Xiaolin;DOU Xiaoliang;CHEN Jianfeng

2006, 57(7): 1704-1708.

Abstract ( 628 )

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Ca1-xSrxZrO3(CSZ) powders were synthesized successfully by the oxalate coprecipitation process.In this study,oxalate acid and a mixture solution of CaCl2, SrCl2 and ZrOCl2 were used as reactants and the product was a precursor of CSZ.TG-DTA curves were employed to characterize the thermal decomposition behavior of the precursor and gave an initial temperature of formation of CSZ crystal.The XRD results revealed also that when heating temperature was up to 1000℃, the powder crystallized was a full solid solution with cubic structure and the relationship of lattice parameter (a) and x agreed with the Vergard’s law.The CSZ powder calcined at 1100℃ was sintered at 1450℃.The SEM micrograph of the sintered ceramics showed that the average grain size was around 0.7 μm,and the relative density of the ceramics was 93.0%.The dielectric constant of the Ca0.8Sr0.2ZrO3 with Sr2+ in solid solution (x) of 0.2 measured at room temperature and under the high frequency of 10 MHz was 27.6.

Structure and performance of polycarbonate urethane

GUO Jintang, LIN Fangqian, LIU Bing, ZHAO Meihua

2006, 57(7): 1709-1714.

Abstract ( 1180 )

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Polycarbonate urethane was synthesized from polycarbonate diol(PCN),4,4′-methylene diphenyl diisocyanate and 1,4-bytanediol by the melting one-shot method.The thermal behavior and microphase separation of the polymer were characterized with DSC and TGA.The distance between microphases was estimated from the data of SAXS.Tensile test was used to analyze the effects of different M_n of PCN and content of soft segment on mechanical properties.The results showed that the polymer had partial microphase separation structure, and this structure was less obvious with the increase of the content of soft segment.There were two types of micro-domains in the continuous phase of polycarbonate，the micro-domain formed with urethane and the micro-domain of polycarbonate crystallization itself.There were two obvious stages in its thermal decomposition on which the effect of the content of soft segment was not obvious.With the increase of the content of PCN, the Young’s Modulus decreased and the elongation at break increased.The as-synthesized polycarbonate urethanes(PCNU)showed a maximum tensile strength of 80 MPa.At the same time, elongation at break was more than 400%.

Absorbency and adsorption of PAAAM in salt solutions

XIE Jianjun;LIU Xinrong;LIANG Jifu

2006, 57(7): 1715-1717.

Abstract ( 566 )

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The absorbencies (Q) of superabsorbent, prepared from acrylic acid and acrylamide by the solution polymerization method, in Cl^- salt solutions were investigated.The results have shown that,Q increased quickly at first and then increased slowly, and at last became constant in NaCl solutions with an increase of swelling time.However, in transitional metal ionic salt solutions,Q increased at first and then decreased with an increase of swelling time.The relationship between adsorption capacity (q) and adsorption time (t) was investigated, a good linear relation between t/q and t was obtained.The relationship between q and the concentration of Fe³⁺(C) was also discussed, and the largest q was 171 mg•g^-1 when C was 0.315 mg•ml^-1.

Preparation and property of polycation PVA

MENG Pingrui;LI Liangbo;QIN Huaixia;LIU Xuechun;CHEN Cuixian

2006, 57(7): 1718-1721.

Abstract ( 947 )

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A novel polycation electrolyte was synthesized by quaternizing polyvinyl alcohol(PVA) with (3-chloro-2-hydroxypropyl)-trimethylammonium chloride (CHTMAC) and using KOH as catalyst.The product was named as quaternized PVA(QAPVA).The factors affecting the quaternization reaction were investigated and optimized.The degree of substitutions of QAPVA increased from 1.0% to 6.7%.QAPVA exhibited higher glass transition temperature.The conductivity of QAPVA aqueous solution showed direct proportional relationship with QAPVA concentration.PVA and QAPVA were further prepared into the dense membranes and observed membrane surface morphology.It was found that the surface of PVA membrane was flat, whereas the surface of QAPVA membrane took on many spherical tubes.Furthermore, the QAPVA membrane showed permeation flux of 250 g•m^-2•h^-1 and separation factor of 1540 when dealing with water/ethanol system ［containing 95.4%（mass）ethanol］ at 75℃.QAPVA was further compounded with phosphatized anionic PVA(PAPVA)to prepare a new polyelectrolyte complex and thereby utilize the new complex to separate water/ethanol［containing 95.4%（mass）ethanol］.The results indicated that the complex had permeation flux of 380 g•m^-2•h^-1 and separation factor of 2250 for water/ethanol system.

Performance of nano-CaCO₃ coated with SiO₂ on CO₂ adsorption at high temperature

WU Rong;WU Sufang

2006, 57(7): 1722-1726.

Abstract ( 758 )

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Nano-CaCO₃ particles were surface-coated with SiO₂ by the sol-gel method and used as the high temperature CO₂ adsorption material.CaCO₃ samples prepared at 60—90℃ were characterized with TEM, EDS and XRD methods and the initial and final decomposition temperature were determined with TGA.The CO₂ adsorption ratio and carbonation-calcination characteristics were evaluated in a φ12 mm fixed bed reactor.The analytical results showed that there was an amorphous SiO₂ film formed on the surface of nano-CaCO₃,and the atomic ratio of Si to Ca is 1∶39.The initial and final decomposition temperatures were 595—620℃ and 800—820℃ respectively.The maximum CO₂ adsorption ratio of SiO₂ coated with nano-CaCO₃ was 92.1% at 600℃with a 10% increase as compared with the uncoated nano-CaCO₃ particles.After 20 cyclic carbonation and calcination runs, CO₂ adsorption ratio of the SiO₂ coated samples was 63%.The XRD analysis illustrated that the crystal type of nano-CaCO₃ had no change after 20 cyclic runs.

New process for extracting cadmium by ammonium-ammonia method

HE Jing;TANG Motang;LIU Wei

2006, 57(7): 1727-1731.

Abstract ( 889 )

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A new process was proposed for extracting cadmium from cadmium-containing raw materials by the ammonium-ammonia method.Investigation on leaching in the process for treating an electric precipitation dust from ISP sintering factory was carried out.The best conditions were established as follows:the ratio of liquid to solid was 2.5,［NH₃］/［NH₄⁺］=3/5,total concentration of ammonium and ammonia was 8 mol•L^-1,the leaching time was 1.5 h at 35℃.Under the above conditions, leaching rate of cadmium and its concentration in the leached solution was 90.99% and 8.74 g•L-1,respectively.

Computer assisted gasoline blending design

ZHANG Yuntao;DUAN Qibin;BAI Chunyan;YANG Xiaoli;ZHENG Wei

2006, 57(7): 1732-1735.

Abstract ( 709 )

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The design of gasoline blending made a linear transformation of the set of variables comprising component octane number, component distillation process data, component proportion of blending gasoline,and additive quantity.With a production-based data LSSVM and ν-SVR and RBFNN machine learning methods the prediction model for octane number was established, and the design was computerized for directing gasoline blending in a petroleum refinery.The experimental results showed that the mean of value of absolute error was 0.227RON,and the maximun absolute error was 0.480RON.The experiments with the absolute error within 0.3RON accounted for 76.2% of the total experiments while those with absolute error within 0.4RON accounts for 90.5% of total experiments.