CIESC Journal

PROTEIN DENATURATION AND REFOLDING DURING CHROMATOGRAPHIC PROCESSES

LI Ming, JanChrister Janson, SU Zhiguo

2004, 55(7): 1033-1040.

Abstract ( 569 )

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The impressing from immobilized medium and moving solution might cause protein conformational change and accompanying loss of protein activity during separation by chromatographic processes. At the same time, the denatured protein might refold to gain their native structure and total activity when they pass through the chromatographic column at suitable operation condition. This review focuses on recent advances in column separation and refolding, which have shown promising results on activity recovery from native protein and refolding yield from inclusion bodies. Suitable chromatographic medium and optimized operation system will affect conformational change and improve the yield of active proteins, which are valuable on both laboratory research and commercial productivity.

EXCESS VOLUME MODEL OF BINARY LIQUID MIXTURES

DING Shujing;SHEN Xiaoyan;LIU Guojie

2004, 55(7): 1041-1046.

Abstract ( 904 )

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According to the thermodynamic model of formation of the solutions containing alcohol proposed in this work, an equation of excess volume was established by adopting the approach to releasing and charging attractive potential energy between two components.It indicated that the excess volumes of solutions containing alcohol were mainly dependent on changes of enthalpies caused by the dissociation of components and cross-association between them and attractive potential energy released or charged in this model. This equation showed good generality and was not only applicable to the solutions containing alcohol, but also to the solutions not containing alcohol. Extensive test proved that it could be used to correlate experimental data of variation of excess volume with composition for all kinds of binary liquid mixtures satisfactorily.

MASS TRANSFER AND HEAT TRANSFER IN CONTINUOUS PLATE DRYER

LIU Xiaolong;JIANG Jialing;LIU Baoqing

2004, 55(7): 1047-1052.

Abstract ( 621 )

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A mathematical model for the heat-mass transfer in a continuous plate dryer was proposed. The calculation of several important parameters, such as height, volume of ringy granule piles on the heating pan and drying time, were made.By using the penetration model of particle heat transfer, exit temperature(T_e), humidity of material exit(X_e) of ringy granular piles and average drying rate(m•) were calculated by iterative equations.The only empirical parameter Nmix, called the mixing number, could be predicted by the method, provided that the experimental data with various input humidity(X_i) were known.The model and equations were used for a published experimental plant.The theoretical predictions were in satisfactory agreement with experimental data, and the error between measured data and calculated values was less than 20%.

THREE-DIMENSIONAL NUMERICAL SIMULATION OF TURBULENT FLOW AND HEAT TRANSFER CHARACTERISTICS IN SHELL SIDE OF SHELL-AND -TUBE HEAT EXCHANGERS

DENG Bin;TAO Wenquan

2004, 55(7): 1053-1059.

Abstract ( 636 )

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A three-dimensional, staggered grid, full-implicit consistent control-volume numerical model was presented for the analysis of turbulence fluid flow and heat transfer in the shell side of shell-and-tube heat exchanger.The numerical model used the distributed resistance method along with the concept of volumetric porosities, surface permeabilities to account for the presence of tubes in the heat exchangers. A modified k-ε model was used to account for the effects of tubes on turbulence generation and dissipation. Shell and baffle walls were modeled by using the wall function approach. The three-dimensional model was validated by comparison of the computed pressure drop distribution with experiment data obtained on an E shell type heat exchanger model and the previous research results. Good agreement between the simulation results and experimental data is obtained. It showed that the three-dimensional numerical model could more effectively simulate the flow characteristics in the shell-side of heat exchanger than the previous numerical simulation models.

ANALYSIS OF HEAT TRANSFER FOR GAS SLIP FLOW IN TRIANGULAR MICRO-CHANNELS WITH UNIFORM HEAT FLUX

ZHU Xun;XIN Mingdao

2004, 55(7): 1060-1065.

Abstract ( 635 )

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In this paper a theoretical analysis of heat transfer characteristics is presented for the fully developed laminar flow of the incompressible gas in the triangular microchannels in slip flow regime.The energy equation with the temperature jump boundary conditions is solved by using a computation-oriented method of the orthonormal function analysis in the triangular microchannels heated with uniform heat flux along flowing direction and with isothermal walls. The theoretical calculations of dimensionless temperature profiles and the average Nusselt number in the microchannels are obtained. The results show that the orthonormal function method is applicable to study the heat transfer characteristics in the triangular microchannels.The average Nusselt number in triangular microchannels is lower for slip flow than that for no-slip flow, and decreases with increasing Knudsen number. The relation curve of average Nusselt number vs the aspect ratio of the triangular microchannels moves downward parallelly with increasing Knudsen number.

ESTIMATION OF TURBULENT KINETIC ENERGY DISSIPATION RATE IN CHANNEL FLOW BY PIV

WANG Hanfeng, LIU Zhaohui, GUO Fushui, ZHENG Chuguang

2004, 55(7): 1066-1071.

Abstract ( 812 )

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Accurate estimation of turbulence dissipation rate is very important for engineering and academic study of turbulence.It is challenging to measure the dissipation rate due to its complex definition. The measurement of the turbulence flow in a horizontal channel was performed by using PIV, and thus the method of using SGS model to estimate the turbulence dissipation rate was introduced and the advantage of such method was analyzed.All the estimation results were compared with the DNS’s results.The outcome of the corrected Smagorinsky model fitted the DNS’s results best.

EFFECTIVE THERMAL CONDUCTIVITY WITHIN MATHEMATICAL MODEL OF SOLID-LIQUID PHASE CHANGE

CHEN Jingliang;TIAN Huaizhang;CHEN Linhui

2004, 55(7): 1072-1076.

Abstract ( 698 )

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Based on the empirical equation of one-dimensional effective thermal conductivity within mathematical model of solid-liquid phase change,a modified equation of effective thermal conductivity is proposed and applied to solving the two-dimensional problem according to mathematical analysis and experimental data. The results of the model simulation are compared with the experimental data and the computing method for effective thermal conductivity is reasonable.

REFRIGERATING CHARACTERISTICS OF SOLID ADSORPTION COOLING TUBE

WU Weidong;MAO Zhengrong;ZHANG Hua;LIU Xunhai;WU Zhimin;WU Yiwen;LIN Hantao

2004, 55(7): 1077-1082.

Abstract ( 635 )

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A solid adsorption cooling tube with a working pair of zeolite-water driven by waste heat is presented in this paper. Firstly, the cooling power for the cooling tube was tested and the varying status of the cooling temperature at different cooling capacities was studied.The performance of the cooling tube showed strong coupling with exterior ambient parameters such as heat source temperature, ambient temperature, air velocity and air relative humidity.A series of experiments for the effects of the ambient parameters on the performance were performed and analyzed.The results indicated that the performance of the cooling tube was very good.The results could be used as the reference for optimizing system design and improving the performance of the cooling tube.An engineering design scheme of adsorption cooling tube air-conditioner was also proposed.

MULTI-FACTOR EFFECTS ON AND CORRELATION OF MINIMUM SPOUT-FLUIDIZING VELOCITY IN SPOUT-FLUID BEDS

TANG Fengxiang;ZHANG Jiyu

2004, 55(7): 1083-1091.

Abstract ( 699 )

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Almost all the literature correlations for predicting the minimum spout-fluidizing velocity, u_msf,were developed from single particle component and special gas-distributor,and hence have some limitation in actual application.In view of this,u_msfof binary particle mixtures were determined in a semi-cylindrical spout-fluid bed of 125 I.D. and 60° conical base angle. Since bed diameter and perforated distributor modes affect obviously the gas dispersion and the exchange between spout and annular region in spout-fluid beds, four functions, i.e.,cos(aθ),sin(bθ),tan(cβ) and f(D_c/D_cref),were proposed to represent the effects of conical angle,θ, uniform gas distribution style， holes orientation angle,β, and bed diameter,D_c, on u_msf, respectively.Based on 590 u_msf data from this work and literatures, six dimensionless numbers, standing for bed geometry, particle properties and momentum at minimum spout-fluidizing conditions, and the above four functions are satisfactorily used to develop a new correlation for predicting umsf with a correlation coefficient 0.97, a deviation ±29.5% and an average deviation 11.5%.

SYNTHESIS OF Ti-MCM-41 MOLECULAR SIEVES BY ELECTROSTATIC S⁺X^-I⁺ ASSEMBLY PATHWAY AND ITS CATALYTIC OXIDATION PERFORMANCE

GUO Jianwei, WANG Lefu, CUI Yingde, LIU Sa

2004, 55(7): 1092-1097.

Abstract ( 677 )

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Ti-containing mesoporous molecular sieves Ti-MCM-41 were synthesized by electrostatic S⁺X^-I⁺ assembly pathway.Influences of different factors on the structure of Ti-MCM-41, as well as catalytic oxidation performance of Ti-MCM-41 on many kinds of alkenes were investigated systematically.Only a part of Ti source could be introduced into the framework of Ti-MCM-41 molecular sieve due to the high solubility of Ti under strongly acidic conditions.Ti content in framework decreased with the increase of HCl/TEOS, while the yield, the unit cell parameter a₀ and the framework wall thickness δ_w of Ti-MCM-41 molecular sieve increased with the increase of HCl/TEOS.The highly ordered of Ti-MCM-41 molecular sieve could be obtained in the wide range of C16TMABr /TEOS（0.3～1.0）and H₂O/TEOS（60～120）.The template could be effectively recovered from the Ti-MCM-41 precursor by extraction with a mixed solvent of acetone-water which would not change the ordered structure of Ti-MCM-41 products. Ti-MCM-41 showed catalytic activity to oxidation of many alkenes with hydrogen peroxide or molecular oxygen as oxidizer. The catalytic activity of Ti-MCM-41 from electrostatic S⁺X^-I⁺ assembly pathway was a little lower than that of Ti-MCM-41 from hydrothermal crystallization.

CATALYZED SYNTHESIS AND CHARACTERIZATION OF 2，2-DIMETHYLOL-1-BUTANAL

FANG Li;ZHAO Yongxiang;QU Jifang;WANG Yongzhao;LIU Diansheng

2004, 55(7): 1098-1102.

Abstract ( 943 )

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2,2-dimethylol-1-butanal(DMB) was synthesized by n-butyraldehyde（NBAL）with paraformaldehyde（PFA）in the existence of triethylamine（TEA）. NBAL reacted completely(＞99％) and the yield of DMB reached 88%.The structure of DMB was characterized by IR、GC、GC-MS、¹HNMR.It was found that the concentration of TEA and H₂O greatly affected the rate of temperature rise of the reaction system and the yield of DMB. The optimized reaction conditions were as follows:under the nitrogen atmosphere,n_NBAL∶n_PFA∶n_TEA=1∶3∶(0.05—0.1)and 10%—15% water by weight, temperature 50—80℃,reaction time 2h.

HEAVY OIL DEEP CATALYTIC CRACKING PROCESS IN DOWNER REACTOR TO PRODUCE LIGHT OLEFINS

LI Qiang;WANG Lei;ZHANG Qihao;LUO Guohua;WEI Fei

2004, 55(7): 1103-1108.

Abstract ( 755 )

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A hot model of a gas-solid circulating fluid downer reactor was built to study the deep catalytic cracking process with DAO feedstock and commercial equilibrium CHP-1 catalyst. The influence of reaction temperature and catalyst to oil ratio(CTO) on product′s distribution was examined. The experiments showed, with the increase of reaction temperature, light olefin yields increased at first to a maximum and then decreased. However, the light olefin yields increased with the increase of CTO. Owing to the short residence time, more uniform gas-solid flow and reduced backmixing of downer reactor, it can obtain more object products and the dry gas yield can be inhibited. The experiment results indicate that the downer reactor is suitable for deep catalytic cracking of heavy oil which needs high severity reaction condition.

GAS FLOW BEHAVIOR IN A ROUGH-CUT CYCLONE IN FCC DISENGAGER

CHAO Zhongxi;SUN Guogang;GONG Bing;SHI Mingxian

2004, 55(7): 1109-1116.

Abstract ( 626 )

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Gas flow behavior in a rough-cut cyclone in FCC disengager was studied. DSM model provided by CFX 5.5 was adopted to predict the gas flow field, and simulation results were compared with experimental data measured by means of five-hole probe. The comparison verified the good power of DSM model. The simulation and experimental results both revealed great differences between a rough-cut cyclone and a traditional one in terms of flow field.There existed reversed flow in the exit tube and dipleg,which could get to the separation space and strongly disturb the flow field. On the basis of the flow field, scalar transport equation was used to compute the gas residence time distribution. Simulation results of gas tracing showed that residence time distribution of the gas from the inlet and out of the dipleg and exit tube assumed logarithmic normal distribution. Gas residence time of the reversed flow took on a double-peak profile. Average gas residence time was increased by 5%—10% approximately for the existence of reversed flow in the exit tube. Decrease of diameter of the dipleg and existence of a hopper could increase mass flux out of the exit tube as well as decrease the reversed flow distinctly, thus the average gas residence time was decreased significantly.

ADSORPTION SEPARATION OF β-NAPHTHALENESULPHONIC ACID WASTEWATER ON WEAKLY BASIC RESIN AND THERMODYNAMICS

LI Changhai;SHI Hongren;TANG Hongyu

2004, 55(7): 1117-1123.

Abstract ( 590 )

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Equilibrium of single component adsorption for β-naphthalenesulphonic acid, sulfuric acid and sulfurous acid from β-naphthalenesulphonic acid wastewater was studied, and the single-solute adsorption data were fitted to the Langmuir and Freundlich models. It could be found from thermodynamic calculation and analysis results that adsorption was a chemical adsorption, adsorption affinity of various acids was H₂SO₄>NSA>H₂SO₃,and adsorption force between resin and acids was H₂SO₄>NSA>H₂SO₃ and entropy was increasing in the course of adsorption.The separation operation could be effectively carried out for these acids based on weakly basic resin D301R.

GROUP-CONTRIBUTION BASED ENSEMBLE NEURAL NETWORK APPROACH TO ESTIMATION OF NORMAL FREEZING POINT OF ORGANIC COMPOUND

2004, 55(7): 1124-1130.

Abstract ( 657 )

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A model was developed to evaluate and predict normal freezing point of organic compounds.This study was based on the group-contribution method and the neural network ensemble technology.The input parameters of neural network were group numbers of organic compounds and isomeric characterization parameters, the output was normal freezing point.The error saturation (ES) condition, which was caused by the use of gradient descent method, would greatly slow down the learning speed of BP algorithm. Having analyzed the causes of the ES condition,an ESP function was proposed to avoid the ES condition from hidden nodes.The simulation result of using ESP method in hidden layers showed that it would reduce the probability of trapping into local minimum in the error surface and accelerate the convergence speed.The ensemble method was used and the neural network ensemble model was established.The nodes in the hidden layer were chosen rationally through simulation,and the cross-validation method was adopted for preventing the BP network from overfitting, which improved the generalization ability of network.According to the ensemble neural network model established in this paper, the estimation result showed that the network had good stability and prediction accuracy and the estimation absolute mean relative error of 207 samples was 8.62%.

ROBUST CONTROL OF ILL CONDITIONED PLANTS

WANG Wei;S.Engell

2004, 55(7): 1131-1134.

Abstract ( 587 )

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A robust control design procedure is proposed for ill-conditioned plants, in which the loop shape design procedure (LSDP) and the frequency response approximation (FRA) method are combined to design a two-degree-of-freedom robust controller: feedback controller and prefilter.The whole design procedure is demonstrated by a well-known control problem of an ill-conditioned plant.

CHEMICAL BEHAVIOR OF BRONZE LOCALIZED CORROSION IN SOIL

WANG Julin, XU Chunchun

2004, 55(7): 1135-1139.

Abstract ( 699 )

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This paper describes a study on the corrosion behavior of archaeological bronze in simulated soil solution (0.028 mol• L^-1 NaCl+0.01 mol•L^-1Na₂SO₄+0.016 mol•L^-1NaHCO₃) by means of simulated occluded cell (O.C.).The present study illustrates the migration, enrichment and deposition patterns of ions in the environment and the cations produced by anodic dissolution during localized corrosion of bronze.The relationship between copper solution factor f_Cu and time is given.The dissolution rate of Sn is higher than that of Cu during the initial period of dissolution. It gradually reverses the trend of dissolution rate i.e. the dissolution rate for Cu is higher than that for Sn. The migration of cations to the bulk solution is obviously observed.

MATHEMATICAL MODEL OF CONTINUOUS ELECTRODEPOSITION OF POROUS METAL

WANG Dianlong;DAI Changsong;WU Ning;JIANG Zhaohua

2004, 55(7): 1140-1144.

Abstract ( 622 )

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In order to prepare the continuous porous metal by electrodeposition, a mathematical model of continuous electrodeposition of strip porous metal under steady state was deduced,based on the transition from time variable to location variable.Furthermore the expression of apparent distribution for current density was derived. This relationship was verified experimentally from the preparation of porous nickel. When the angle between porous metal strip and anode configuration conformed to the same angle the apparent current density could be kept constant, and nickel crystal was compact.This work provided the theoretical foundation of on-line control in preparing porous metal by electrodeposition.

BIOLEACHING OF MARMATITE FLOTATION CONCENTRATE

SHI Shaoyuan;FANG Zhaoheng

2004, 55(7): 1145-1149.

Abstract ( 876 )

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The bioleaching of marmatite flotation concentrates by Acidithiobacillusferrooxidans was investigated.The leaching effects under the conditions of uninoculated, inoculated original strains, inoculated adapted strains were studied and the biooxidation rates of marmatite leached by the adapted strains for different pulp density values were determined.The experimental results on an orbital shaker showed that the adapted Acidithiobacillus ferrooxidans increased markedly the dissolution rate and the leaching ratio of marmatite under the leaching conditions of pH 2.0, temperature 35 ℃, 10% inoculating volume of microorganisms, 5% pulp density, <35.5μm particle size and rotating speed of a shaker 160r•min^-1.The increase of pulp density resulted in the decrease of the leaching ratio of Zn in marmatite minerals, and the increase of totally leached concentration of Zn²⁺ ions per unit time.

INFLUENCES OF OSMOLYTES ON CELLULAR PROLIFERATION, MORPHOLOGY AND VIABILITY OF Saccharomyces cerevisiae

WANG Yajun;YAO Shanjing;WU Tianxing

2004, 55(7): 1150-1154.

Abstract ( 654 )

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Much attention has been paid to the influences of osmosis on Saccharomyces cerevisiae, due to the increasing application in the food and pharmaceutical industries, biotransformations. Besides, to maintain an appropriate turgor is of crucial importance to individual growth, cellular division and viability.In the study, to evaluate the impacts of different osmolytes on cellular proliferation, morphology and viability of the model microbe Saccharomyces cerevisiae FL 1, in additon to the commonly used sodium chloride, glycerol, poly(ethyleneglycol)600, and sorbitol were used.Moreover, the dynamic behavior of cell proliferation and metabolism under physiologicallg acceptable hyperosmotic condition were examined. Results indicated that these osmolytes had significant negative impacts on proliferation with increasing concentration, compared to the control treatment composed of YEPD media. The cellular morphology was close to sphere after exposure to high osmotic pressure for 24 h. After analyzing the dynamics data, sodium chloride of 0.5 mol•L^-1 was found to markedly reduce the specific cell growth rate, sugar consumption but prolong the duration of exponential growth phase. At the same time, PEG600 of 0.33 mol•L^-1 had no marked influence on cell proliferation but shortened the stationary phase.However, under the physiologically acceptable hyperosmotic condition, the final biomass density among all the treatments was similar.

INFLUENCE OF OPERATING PARAMETERS ON PULSE CLEANING PROCESS OF CERAMIC FILTER

JIAO Haiqing;JI Zhongli;CHEN Honghai;SHI Mingxian

2004, 55(7): 1155-1160.

Abstract ( 647 )

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A cold-model filter experimental set-up, with a single ceramic candle filter element, was built to gain more insight into the surface regeneration process.A U-tube manometer was used to obtain pressure drop traces across the filter and a resistance-type pressure transducer was used to measure the internal transient pressures within the candle during pulse-jet cleaning.There exist definite fluctuations in cleaning efficiency even for continuously stable cycle of ceramic filter.When the filtration parameters were changed and the pulse jet parameters are held constant, the cleaning effectiveness could be inferred by the pressure inside the filter element.The influence of operating parameters on cleaning efficiency was also analyzed.The valve opening time almost showed no effect on [JP2]cleaning efficiency.On the basis of meeting the cleaning requirements, excessive reservoir pressure showed little influence on cleaning efficiency. Excessive filtration velocity is disadvantageous, which could lead to the failure of stable operation of the filter unit.[

NUMERICAL SIMULATION OF GAS-COMPONENTS DISTRIBUTION IN PRE-CALCINER

HUANG Lai;LU Jidong;DI Dongren;HU Zhijuan;LIU Ruizhi

2004, 55(7): 1161-1167.

Abstract ( 630 )

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A 3D numerical simulation study was performed to simulate the physical and chemical processes in two-spray pre-calciner widely used in cement production.The relation between gas components distribution and rates of coal combustion and carbonate decomposition was studied.A calcium carbonate decomposition model applicable for industrial analysis based on previous work was used, and the total coal combustion rate and total carbonate decomposition rate were obtained by using numerical simulation.This article presents a method for predicting the distribution of gas components coming from different sources and provides theoretical information for the analysis of coal combustion and calcium carbonate decomposition on the commercial scale.

KINETICS OF ACRYLATES COPOLYMERIZATION IN INVERSE MICROEMULSION

LI Xiao;GAO Jing;ZHANG Weiying;ZENG Weijie

2004, 55(7): 1168-1172.

Abstract ( 618 )

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The kinetics of acrylates copolymerization initiated with azobisisobutyronitrile (AIBN) in inverse microemulsions composed of methyl methacrylate (MMA)-butyl acrylate (BA) / dodecyl sodium sulfate (SDS)-acrylic acid(AA)/water was studied. The results showed that the apparent polymerization rate at 5% conversion increased with increased AIBN concentration, AA concentration, aqueous fraction and reaction temperature while decreased with increased SDS concentration, and the kinetic relation was obtained.Nucleation in aqueous droplet was considered to be important.Furthermore, the total apparent activation energy was found to be 114 kJ•mol^-1.

NUMERICAL ANALYSIS OF INITIATION OF INTERFACE INSTABILITY IN POLYMER MULTIPHASE-MULTILAYER CAVITY FILLING FLOW MOLDING

ZHOU Guofa

2004, 55(7): 1173-1178.

Abstract ( 996 )

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On the basis of the engineering background of advanced polymer multi-component molding techniques, the fully three-dimensional unsteady non-isothermal theoretical model of multiphase-multilayer cavity filling flow is established in this paper and the corresponding stable numerical algorithm with fast convergence is put forward.By means of numerical simulation research, the quantitative comparisons of initiation and patterns of interface instability under various rheological parameters and process parameters are presented.Therefore, the initiation mechanism of interface instability is disclosured by theoretical analysis, and the dependence of interface instability on rheological parameters and process parameters are studied.The results of simulation have a good agreement with the experiment results given by Mohammad et al.

IMPROVEMENT ON THIONYL CHLORIDE METHOD TO ACTIVATE HYDROXYL GROUP OF POLYMER FOR AFFINITY PARTITION

LU Jin;LIN Dongqiang;YAO Shanjing

2004, 55(7): 1179-1182.

Abstract ( 1101 )

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The activation of hydroxyl group is a key step in the synthesis of ligand-polymer for affinity partition. Using thionyl chloride as the chloridating agent and polyethylene glycol (PEG) as the model polymer, the conventional process was improved by introducing triethylamine(Et₃N) into the reaction system.The precipitate of Et₃N•HCl formed in the system promotes the reaction into a thermodynamically beneficial process, which significantly reduced the dosage of thionyl chloride and simplified the synthesis procedure.The mole ratio of reaction materials（SOCl₂，Et₃N and PEG），reaction temperature and reaction time were investigated and optimized.A high value of the synthetic yield was reached at 1.54 mol Cl •(mol PEG)^-1.The comparisons to the conventional thionyl chloride method and epichlorohydrin method were also discussed.

COMMERCIAL TRIAL ON METALLOCENE ADDUCT TECHNOLOGY

CHEN Wei, ZHENG Gang, WANG Ru’en, XU Xin, GUO Zifang, WANG Hongtao, YANG Baozhu, HAN Yanqing, JING Xianghua

2004, 55(7): 1183-1187.

Abstract ( 617 )

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Metallocene catalyst was prepared based on the SINOPEC[DK]’s “Metallocene Adduct Technology”.Great effort was paid on the support procedure to obtain the supported catalysts. The supported catalysts were evaluated in slurry, loop slurry and gas phase fluidized bed pilot plant of polyethylene processes respectively. The metallocene adduct catalyst could catalyze the polymerization of ethylene as well as the co-polymerization of ethylene with α-olefin. Based on the pilot plant experiment results the commercial trial was carried out successfully in a 60000 t•a-1 plant of gas phase fluidized bed polyethylene process for the production of metallocene-based linear low density polyethylene. The resin-grade switching technology between metallocene adduct and Ziegler catalyst was investigated. The influence of the supported catalyst composition and the polymerization controlling parameters on the properties of the obtained polyethylene resin was also studied.The processability and performance of the film-grade resin seem to be acceptable as compared to the analogous materials in the commercial mLLDPE market.

KINEMATIC VISCOSITY OF SATURATED LIQUID DMM

MENG Xianyang;WU Jiangtao;LIU Zhigang

2004, 55(7): 1188-1191.

Abstract ( 805 )

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The kinematic viscosity values of the saturated liquid dimethoxy methane are reported over the temperature range from 248.467 to 353.154 K along the saturation line made with a calibrated Ubbelohde-type capillary viscometer.The total experimental uncertainty is less than 0.71%.In addition, the results were correlated as a function of temperature for the kinematic viscosity equation of saturated liquid. The absolute average deviation and the maximum deviation of the experimental results from the correlated equation are 0.35% and 1.45%, respectively.

MEASUREMENT AND CORRELATION OF SOLUBILITIES OF 4-HYDROXYBENZALDEHYDE AND ITS BROMO-DERIVATIVES IN CHOROFORM

WEI Dongwei;JIANG Haoxi;JING Xin;YUAN Jitang

2004, 55(7): 1192-1195.

Abstract ( 676 )

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Solubilities of 4-hydroxybenzaldehyde, 3-bromo-4-hydroxybenzaldehyde, 3,5-dibromo-4-hydroxybenzaldehyde in chloroform were measured at temperatures ranging from 283.15K to 323.15K.The measurements of temperature and enthalpy of fusion of pure solutes were used for caculation of solubility by ideal solution model,which was higher than the experimental values.The very low solubility in chloroform was due to self association of solute molecules.A λh formula was used to fit the data and had shown good correlation results.

INFINITE DIFFUSION COEFFICIENTS IN HIGH-PRESSURE ETHANOL:EXPERIMENTAL MEASUREMENT AND MODEL EVALUATION

ZHANG Baoquan, CHU Caiyun, LIU Xiufeng, LI Yongdan

2004, 55(7): 1196-1200.

Abstract ( 733 )

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The infinite diffusion coefficients of benzene, toluene, naphthalene, pyridine and p-nitroaniline in ethanol were measured by Taylor dispersion technique under 313—473 K and 0—16 MPa.The measurement accuracy of the established apparatus was first checked.The measured diffusion coefficient of the five organic solutes in ethanol did not change with pressure at low temperature, but it was significantly reduced with pressure increase when the temperature is higher than 373 K.Of the correlations available for polar solvents,the modified Wilke-Chang equation,the Yang-Zhang equation as well as the He-Yu equation were used to calculate the infinite diffusion coefficient. At low temperature, the three equations all agreed well with experimental results for both polar and non-polar solutes.However, the prediction accuracy was decreased sharply when the temperature was higher than 373 K, where the association factor of the solvent was varied with temperature as well as pressure.

PREPARATION AND CATALYTIC PROPERTY OF COPPER ALUMINUM BORATE IN SYNTHESIS OF INDOLE

GUO Cheng;WANG Jianqiang;HUANG Jiarui

2004, 55(7): 1201-1205.

Abstract ( 952 )

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The catalyst copper aluminum borate were prepared by coprecipitation and modification of B and Cu contents.In a fixed bed reactor indole was synthesized by using the catalyst.The crystal structure of the catalyst was characterized by XRD.The results indicated that the conversion rate was 90% and the yield of indole was 95% over the copper aluminum borate catalyst.B and Cu were two active centers of the catalyst.

New Isothermal Model for Grain Growth in Nanocrystallites

QU Yixin;SONG Xiaolan

2004, 55(7): 1206-1207.

Abstract ( 523 )

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