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The Chinese Journal of Process Engineering 2005 Vol.5 Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Heat Transfer in the Fixed Bed Embedded with a Cylinder in Cross Flow---I. Temperature Distribution in the Fixed Bed LIU Yu-lan;XU Zhi-gang;WU Yong-qiang;ZHU Zi-bin    2005, 5 (1): 1-5.   Abstract （1939）      PDF （87KB）（813）       Knowledge map    Save An experimental study was conducted on the cross-flow heat transfer in a fixed-bed, and simulated by a two-dimensional model. The contrast of simulation with experimental measurments suggests that the zone affected by the heat transfer is mainly downstream along the cylinder, and less effect is in the other directions. The cross-flow heat transfer is closely relied on the fluid flow, and heat is mostly transferred in the same direction as the fluid flows. The larger the Reynolds number is, the smaller the range of isothermal line changes, and the smaller the width of heated zone is. The local heat-transfer coefficient hw and the bed effective thermal conductivity b conform to the following correlations: hwDP/ f=14.77+0.058RepPr, b/ f=15.14+0.296RepPr. Related Articles | Metrics Select Heat Transfer in the Fixed Bed Embedded with a Cylinder in Cross Flow---II. Overall Wall Heat Transfer Coefficient Correlations LIU Yu-lan;WU Yong-qiang;ZHU Zhong-nan;ZHU Zi-bin    2005, 5 (1): 6-9.   Abstract （3056）      PDF （81KB）（804）       Knowledge map    Save The cross-flow heat transfer was discussed on a cylinder tube embedded in the fixed bed. The bed was packed with different kinds of particles which have dissimilar thermal conductivity. The medium of heat transfer was air, and the tube was heated. Under the conditions of Rep 10 180, Db/Dp 28 116, bo/ s 0.5 0.2, the following correlation was obtained by means of the least square method：Nuf 31( bo/ s)1.4(Db/Dp)0.2Rep0.33Pr0.62. Here the Reynolds number is based on the particle surface-equivalent diameter, Nusselt number is calculated by the overall wall heat transfer coefficient, the gas thermal conductivity and the diameter of heated tube embedded in the fixed bed. It is found that for cross-flow heat transfer, Reynolds number is still an important factor affecting heat transfer. Nusselt number has relations with bed characteristic parameter Db, particle equivalent diameter in outer surface Dp and thermal conductivity of packed bed. Related Articles | Metrics Select Two-dimensional Simulation for Hydrogen/Air Combustion in a Monolith Reactor HONG Ruo-yu;DING Jian-min;Vlachos D G    2005, 5 (1): 10-17.   Abstract （1869）      PDF （242KB）（935）       Knowledge map    Save Recent studies on hydrogen combustion were reviewed briefly. The laminar flow and combustion of premixed hydrogen/air mixture in a cylindrical channel of a monolith reactor with and without catalytic wall was numerically modeled by solving two-dimensional (2-D) Navier Stokes (N S) equations, energy equation, and species equations. Eight gas species and twenty reversible gas reactions were considered. The control volume technique and the SIMPLE algorithm were used to solve the partial differential equations. The streamlines of the flow field, temperature contours, the entrance length, and the concentration fields were computed. It is found that the entrance zone plays an important role on flow and temperature as well as species distribution. Therefore, the flow cannot be assumed either as fully developed or as plug flow. There is a small but strong thermal expansion zone between the wall and the entrance. Both diffusion and convection affect the heat and mass transfer processes in the expansion zone. Thus the equations of momentum, energy and species conservations should be used to describe hydrogen/air combustion in the monolith reactor. The hot-spot location and concentration field of the homogeneous combustion is strongly influenced by the inlet velocity and temperature, and the equivalence ratio. The catalytic combustion of premixed hydrogen/air mixture over platinum catalyst-coated wall in a cylindrical channel was also simulated. Related Articles | Metrics Select One-dimensional Model of a Multiple-unit Pneumatic Transport Reactor for Producing Titanium Tetrachloride---II. Simulated Results on Reactor Behavio XU Cong;YUAN Zhang-fu;WANG Xiao-qiang    2005, 5 (1): 18-22.   Abstract （1729）      PDF （107KB）（757）       Knowledge map    Save The multiple-unit pneumatic transport reactor is an innovative reactor suitable for gas solid reaction system to avoid adhesion and agglomeration or enhance mass transfer rate. The effects of initial oxygen concentration, initial chlorine concentration and initial ratio of petrocoke to ore on the characteristics and behaviors of the multiple-unit pneumatic transport reactor for producing titanium tetrachloride are simulated and analyzed. It is found that the conversion of high grade titania feedstock (HGTF) can be enhanced by increasing the initial concentrations of oxygen and chlorine. But CaCl2 and MgCl2 can not be efficiently diluted by petrocoke while the initial concentration of oxygen is greater enough, and the conversion of HGTF can not be further enhanced by increasing initial concentration of chlorine that is excessively high. Moreover, the limiting conversion of HGTF exists for initial ratio of petrocoke to ore, and the heat balance for MPTB can not be achieved between 973 K and 1373 K while the initial concentration of oxygen or the initial ratio of petrocoke to ore are lower than a certain value. Related Articles | Metrics Select Kinetics on Chlorination Process of La2O3 and CeO2 by Ammonium Chloride SHI Wen-zhong;ZHANG Xin;ZHAO Yong-he;WANG Jing-yan;ZHU Guo-cai    2005, 5 (1): 23-28.   Abstract （2752）      PDF （101KB）（2122）       Knowledge map    Save Using ammonium chloride (NH4Cl) as a chlorinating agent, the effects of chlorinating temperature, time and NH4Cl dosage on chlorination of La2O3 and CeO2, and the thermal decomposition of LaCl3 7H2O and CeCl3 7H2O were examined. The results show that NH4Cl directly participates the chlorination reaction, and HCl from pyrolysis of NH4Cl also contributes to the chlorination reaction. CeCl3 and LaCl3 can cause gas phase hydrosols formation or oxidation reaction which generates LaOCl, CeOCl and CeO2. The apparent activation energies of La2O3 and CeO2 chlorination reactions, Ea, are 43.73 and 140.67 kJ/mol respectively. The process is mainly controlled by the interfacial chemical reaction. Related Articles | Metrics Select Thermodynamics of Solvent Extraction of Re(VII) with N8161 FANG Da-wei;WANG Shu-kun;LIU Xing-zhi;ZHAO Di;ZANG Shu-liang    2005, 5 (1): 29-31.   Abstract （1567）      PDF （83KB）（647）       Knowledge map    Save This paper reported the thermodynamics of extracting Re(VII) with the extractant of N8161 in the HCl system. The equilibrium molalities of ReO4 in the extraction: N8161(org) H (aq) ReO4 (aq) H N8161ReO4 (org) were measured at ionic strength values from 0.1 to 2.0 mol/kg in the aqueous phase containing NH4Cl as the supporting electrolyte and at constant initial molality of extractant in the organic phase at the temperatures from 278.15 to 298.15 K. The standard equilibrium constant K0 at various temperatures was obtained, and the thermodynamic variations for the extraction process were calculated. Related Articles | Metrics Select Removal of Sulfur Compounds from FCC Gasoline by Olefinic Alkylation of Thiophenic Sulfur over Solid Acid Catalyst LUO Guo-hua;XU Xin;YANG Chun-yu;TONG Ze-min;PENG Shao-yi    2005, 5 (1): 32-35.   Abstract （2672）      PDF （76KB）（688）       Knowledge map    Save The influences of reaction conditions, including reaction temperature, pressure and diolefin impurity, on the catalysis performance of acid catalyst of AlCl3-supported CT175 resin have been studied by the alkylation reaction of thiophene as a model sulfur compound with isopentene as an alkylation agent. Under the reaction conditions of reaction temperature 100~110℃ and reaction pressure lower than 3.0 MPa, the decrease of the alkylation activity of AlCl3 CT175 catalyst results from the polymerization reaction of diolefin impurity in the feedstock over the surface of catalyst. However, AlCl3 CT175 catalyst shows excellent alkylation activity and stability when the reaction pressure is higher than 3.0 MPa, and the conversion of thiophene is nearly 100%. The desulfurization effectiveness of AlCl3 CT175 as catalyst for the removal of thiophenic sulfur compounds from the fraction of 60~150℃ boiling range of FCC gasoline is also investigated at the reaction conditions of 110℃, 3.0 MPa and 2.33 h 1 (WHSV), and the results show that over 98% of thiophenic sulfur compounds are converted into multi-alkylthiophene, and the diolefins in this fraction are effectively removed. Related Articles | Metrics Select Desalination of Fermented Broth Containing 1,3-Propanediol by Electrodialysis HAO Jian;LIU De-hua    2005, 5 (1): 36-39.   Abstract （1640）      PDF （63KB）（768）       Knowledge map    Save The desalination of fermented broth containing 1,3-propanediol by electrodialysis was studied. The relationship between fermentation broth conductance and temperature, effects of membrane pair voltage, pretreatment with flocculation or filtration, initial pH of fermented broth on desalination, and reuse time of membrane were also investigated. It is found that the conductance of fermented broth is linearly related to temperature, the correct coefficient of temperature is 0.0217; the optimal operation voltage over membrane pair is 1.3~1.5 V, the longer the time taken for desalination, the more loss of 1,3-propanediol, flocculation with chitin will decrease the concentration of protein in broth, then alleviate the fouling process of membrane, and improve the efficiency of desalination. Initial broth pH has a noticeable affection on desalination in the pH range of 5~8, and the lower the pH of broth, the lower the resistance of membrane pair. So adjusting broth pH to an acidic condition will accelerate the rate of desalination. After using 15 times, membranes should be cleaned with NaOH and NaCl solution for the reason of fouling. Related Articles | Metrics Select Separation and Purification of 2,6-Diisoproylnaphthalene LI Wen-yan;YANG Chun-yu;JIN Hi-bo;LUO Guo-hua;HE Guang-xiang    2005, 5 (1): 40-43.   Abstract （1738）      PDF （66KB）（713）       Knowledge map    Save The separation and purification of 2,6-diisopropylnaphthalene from the products prepared by alkylation of naphthalene and propylene are studied. The influence of operation conditions on distillation separation and that of crystallization temperature and solvent on purity and yield of the final product are examined. The experimental results show that the purity of 2,6-diisopropylnaphthalene is about 50% by collecting 165℃ distillate under the vacuum of 1000 Pa. Final product of 2,6-diisopropylnaphthalene with purity 99.42% is gained after the distillate is crystallized at 9℃ and the crystal is washed by ethanol. Related Articles | Metrics Select Preparation of Acetylized Polystyrene Carrier by Friedel Crafts Acetylation Reaction BIAN Guo-jian;WEI Rong-qing;LIU Xiao-ning;WANG Ning;OUYANG Ping-kai    2005, 5 (1): 44-48.   Abstract （1754）      PDF （59KB）（998）       Knowledge map    Save The functional acetylized polystyrene particles were prepared by Friedel Crafts acetylation on polystyrene (PS). The obtained particles may be used as the solid support in flexible immobilization of enzyme, and ion exchange and adsorption. The reported method avoided the toxic problem caused by classic chloromethylation process and eliminated side reactions such as multi-substitution and secondary cross link. In this work, the effects of catalyst, acylating reagent, time and solvent were studied to achieve optimum results. By controlling the amount of materials (catalyst, acylating reagent), the quantitative loading of acetylized resin could be attained. The maximum loading of the acetyl polystyrene could be to 5.9 mmol/g. Related Articles | Metrics Select Preparation of a New Amino Resin by Mannich Reaction ZHU Jian-xing;WEI Rong-qing;LIU Xiao-ning;BIAN Guo-jian;OUYANG Ping-kai    2005, 5 (1): 49-53.   Abstract （1665）      PDF （75KB）（658）       Knowledge map    Save A new amino resin was prepared from acetylated polystyrene micro-beads, formaldehyde and tetraethylene pentamine by the Mannich reaction, which can be substituted for anion-exchange resin prepared from chloromethyl polystyrene resin and immobilization support of enzyme. Influencing factors such as molar ratio of materials, reaction temperature and time, feeding methods as well as water in ethanol medium were discussed. The optimum experimental conditions were gained as follows: tetraethlene pentamine:formaldehyde: hydrochloride:acetyl(mole ratio) 10:10:3.3:1, reaction temperature 100℃, and reaction time 12 h. Under these experimental conditions, the product containing 13.7 mmol/g of nitrogen was obtained. The multi-substitution reaction of acetyl groups was also discussed. Related Articles | Metrics Select Preparation of Nanostructured Lipid Carriers Loaded with Retinoic Acid by the High Pressure Homogenization Method ZHANG Xiao-jia;XIA Qiang;MA Quan-hong;DUAN Lei;GU Ning    2005, 5 (1): 54-57.   Abstract （4081）      PDF （198KB）（757）       Knowledge map    Save The poor aqueous solubility and instability of retinoic acid (RA) have limited its clinical use. Solid lipid nanoparticles (SLN) have a potential limitation which is the drug expulsion. This study was undertaken to overcome the limitation by loading RA in nanostructured lipid carriers (NLC). RA-loaded NLC was prepared by high pressure homogenization and characterized by transmission electronic microscope (TEM), particle size analyzer, zeta potential analyzer and high-performance liquid chromatography (HPLC). The results were as follows: (1) When the homogenization cycle number varied from 1 to 12, the mean particle size decreased from 120 nm to 10 nm, while P.I. (polydispersity index) increased from 0.26 to 0.69. (2) The spherical shape observed by TEM indicated a better drug loading capacity over SLN. (3) The concentration of all-trans retinoic acid (ATRA) in NLC reached 56.26 g/mL compared to 20 g/mL dissolved in silicone oil and the photostability of ATRA was improved so that the effective concentration of RA could keep for a longer time. (4) As far as the stability of NLC was concerned, its potential value was ( 30.9 0.6) mV and it remained stable after 120 min centrifugation (4℃, 10000 r/min) or 6 month light-proof storage. Furthermore, freezing-drying ( 40℃, 0.01 Pa), which increased its mean particle size and reduced its P.I., could also be used to increase the NLC stability. Taken together, RA-loaded NLC is a promising drug form for clinical use. Related Articles | Metrics Select Agglomeration and Precipitation of Mg(OH)2 Particles in the Presence of Polyacrylamide XIANG Lan;WANG Tang;WU Qing-liu;JIN Yong    2005, 5 (1): 58-61.   Abstract （1666）      PDF （1207KB）（657）       Knowledge map    Save The agglomeration and precipitation behaviors of Mg(OH)2 particles in the presence of anionic polyacrylamide with a molecular weight of 15 million were studied. The change of properties of the Mg(OH)2 suspensions such as precipitation volume,distribution of cluster size, ζ-potential and functional groups was investigated to reveal the role of polyacrylamide in the precipitation and agglomeration process of Mg(OH)2 particles. Experimental results indicate that the presence of anionic polyacrylamide can acceler-ate the agglomeration and precipitation of Mg(OH)2 particles via absorption-bridging and electric neutralization routes, and has little influence on the morphology of the hydrothermal products. In the range of 0~125 10 6 anionic polyacrylamide, the increase of concen-tration of anionic polyacrylamide is favorable for the formation of Mg(OH)2 clusters with bigger sizes, leading to the acceleration of agglomeration and precipitation of Mg(OH)2 clusters. Related Articles | Metrics Select Dispersion Behavior of Nanosized TiN Powder in Water and Absolute Ethyl Alcohol FENG Ping;XIONG Wei-hao    2005, 5 (1): 62-65.   Abstract （1875）      PDF （146KB）（671）       Knowledge map    Save By means of the measurement of particle size and potential of particles, the dispersion of TiN nanoparticles and the effect of surfactants on the dispersion in water and absolute ethyl alcohol were investigated. It was revealed that pH value had a strong influence on the dispersibility for TiN nanoparticles in water, and at pH 8, dispersed result was optimal. With the increase of pH, the carried charge of particles was altered from positive to negative state, and IEP equaled 3.7. The dispersibility followed the mechanism of electrostatic stabilization. However, the pH value had a week effect on the dispersibility of TiN nanoparticles in absolute ethyl alcohol, in the whole range of pH, the particles carried positive charges. Solvent layer dominated the dispersibility. Surfactant polyoxyethylene do-decyl ether might be acted as dispersant in water, and polyethylene glycol as dispersant in water and absolute ethyl alcohol. Related Articles | Metrics Select Preparation and Photocatalysis Performance of BaSO4/TiO2 Composite Particles CHEN Gui-guang;LUO Guang-sheng;YANG Xue-rui;SUN Yi-wen;WANG Jia-ding    2005, 5 (1): 66-69.   Abstract （1656）      PDF （298KB）（749）       Knowledge map    Save Composite BaSO4/TiO2 particles were prepared by a 3-step membrane dispersion precipitation method. The structure of the composite material was analyzed by TEM and electron diffraction, and the photocatalysis performance was investigated in a self-designed reactor. The results show that BaSO4 can be coated by TiO2 nano-particles effectively with the multi-step precipitation method. The particle size and crystal type of TiO2 on the surface and photocatalysis performance of the composite particles were affected by the concentration of Ti(SO4)2. An increase in concentration of Ti(SO4)2 and with NH4HCO3 as precipitator was of benefit to the preparation of anatase-TiO2/BaSO4 particles and to the improvement of their photocatalysis performance. The photocatalytic degradation kinetics for methylic orange is of zero order. Related Articles | Metrics Select Preparation and Characterization of PMMA/K2O?6TiO2 Composite Particles CHEN Wei-ping;FENG Xin;SUN Sheng-hua;WANG Chang-song;LU Xiao-hua    2005, 5 (1): 70-73.   Abstract （1624）      PDF （2024KB）（691）       Knowledge map    Save This paper presented a method for modifying potassium titanate whiskers (K2O?6TiO2) to obtain polymethyl methacrylate (PMMA)/K2O?6TiO2 composite particles through emulsion polymerization. The effects of reaction time, initiator concentration, monomer concentration and reaction temperature on the efficiency of conversion or percentage of weight gain were investigated in details. The optimal conditions to reach high conversion efficiency were found. According to the characterization of TGA and SEM, the potassium titanate whiskers were modified through covering PMMA on their surfaces. The characterization of dynamic wetting capacity showed that K2O?6TiO2 was modified from hydrophilic to hydrophobic states. Related Articles | Metrics Select A New Method for Ceric Hydroxide Synthesis ZHONG Xue-ming;DENG An-min;SHU Hong-ying;WANG Yong    2005, 5 (1): 74-77.   Abstract （1723）      PDF （672KB）（871）       Knowledge map    Save A green method for ceric hydroxide synthesis with cerium carbonate and hydrogen peroxide as main raw materials is reported, and two products, ceric hydroxide and sodium acetate, are obtained. The effects of feeding procedure of hydrogen peroxide, the amount of hydrogen peroxide added, reaction temperature, cerium acetate concentration and sodium hydroxide added on the oxidation of cerium are investigated. Ceric hydroxide is characterized by a scanning electron microscope. The oxidation percentage of cerium is over 98 , and the recovery over 99%. Related Articles | Metrics Select Effects of Al(OH)3 Seeding on Carbonization of Sodium Aluminate Liquor in the Sintering Process WANG Zhi;BI Shi-wen;YANG Yi-hong    2005, 5 (1): 78-81.   Abstract （1658）      PDF （1138KB）（712）       Knowledge map    Save Poor product strength and excessive fine particle content are the main problems to be solved in sandy alumina production. Carbonization was investigated through adding seeds to sodium aluminate liquor, and orthogonal experiments were conducted on operation conditions in order to improve the particle size and strength of products. By comparison of mean particle size, attrition index and micrographs of products under the conditions with and without seed, it was shown that seeds played important roles in the carbonization process, and the product mean particle size was influenced by that of seed, but its effect was related to seed type and seed ratio. In addition, seeds could accelerate the inter-growth of unit crystal, as a result the strength of products was increased by 3%-25% . Related Articles | Metrics Select Synthesis of Zinc Carbonate Nano-crystals with a Novel Method and Data Mining JIANG Qiu-yu;LIAO Sen;WANG Jian-she;GUAN Yu-shi;LUO Fen;ZHANG Kai-fen    2005, 5 (1): 82-85.   Abstract （1635）      PDF （952KB）（960）       Knowledge map    Save Solid state reaction occurred when ZnSO4 7H2O and NH4HCO3 powders were mixed and grinded at room temperature with surfactant PEG-400 added. Then, the soluble inorganic salts were removed by washing with water, and the fully crystallized and pure nanometer zinc carbonate precursor was obtained after it was dried. This was a new and simple method for synthesizing precursor of zinc oxide. Based on the uniform design, stepwise regression and optimization calculation, data mining was conducted to the small database from synthesis of nanometer zinc carbonate. The optimization parameters of the experiment were gained: 1:1 in molecular ratio of NH4HCO3 to ZnSO4 7H2O(based on 10 mmol of Zn), 20 μL in volume of PEG-400, and 40 min in grinding time. Under such conditions, the average diameter of particles for the zinc carbonate powder was about 35 nm. The nanometer zinc oxide was obtained when the zinc carbonate was pyrolyzed at 350℃ for 2 h, and its average diameter of particles was about 20 nm. Related Articles | Metrics Select Process Optimization in Modification of rhG-CSF with Polyethylene Glycol YANG Rui-e;MOU Qiang;CHEN Ting;TAN Tian-wei;MA Guang-hui;SU Zhi-guo    2005, 5 (1): 86-89.   Abstract （1754）      PDF （84KB）（677）       Knowledge map    Save Recombinant human granulocyte colony-stimulating factor (rhG-CSF) was chemically modified with mPEG.The effects of reaction conditions on modification degree and in vitro bioactivity were investigated through orthogonal design of the experiment. The optimized reaction condition was borate buffer pH 7.6, molar ratio of PEG to G-CSF(25:1), reaction time 40min and reaction temperature 4℃. Under the optimized reaction condition , the bioactivity of PEG-G-CSF retained 40% while the modification degree was 50%. Different formulations had important influence on the storage activity of the pegylated product . Addition of mannitol and human serum albumin to the solution of PEG-G-CSF could maintain the bioactivity upto 92% for one month and 51% for three months when stored at 4℃. Related Articles | Metrics Select Two-tier Optimization Method for Reaction Path Synthesis HU Shan-ying;LI Ming-heng;LI You-run;SHEN Jing-zhu    2005, 5 (1): 90-93.   Abstract （1672）      PDF （65KB）（668）       Knowledge map    Save Based on the conception of simple stoichiometric reaction, a two-tier optimization method for complex reaction path synthesis problems is addressed. On the first level, a feasible and economic optimal overall reaction is searched by enumerating all simple stoichiometric reactions. Then, these reactions are sorted by gross profits. And evaluations for each reaction from kinetic, thermodynamic and environmental aspects are made. The feasible reaction that has the best profit will be appointed as the reference reaction. The overall reaction of which the profit is less than that of the reference reaction will be abnegated. Those reactions that have better economic potential but are unfeasible will then be tried to be decomposed into several feasible division reactions that take place under different operating conditions on the second level. If the decomposition is possible, the result will be the best reaction path; otherwise the reference reaction is the best result. A case study shows that the method can efficiently solve practical reaction path synthesis problems. Related Articles | Metrics Select Mass Closed Cycle Approach to Reaction Path Synthesis HU Shan-ying;LI Ming-heng;LI You-run;SHEN Jing-zhu    2005, 5 (1): 94-96.   Abstract （1589）      PDF （61KB）（739）       Knowledge map    Save It is important to achieve zero waste emission for reaction path synthesis of mass closed cycle system. This is generally realized by poly-generation of multi-products. The proposed approach consists of 5 steps. Based on the reaction network composed of simple stoichiometric reactions among the related species, a mathematical programming model is built to solve the optimal mass closed cycle reaction path. Finally a reaction path with zero waste is obtained. A case study shows that the method can be used to realize mass closed cycle reaction path. Related Articles | Metrics Select Simulation of Molecular Distillation between Coaxial Cylinder at High Vacuum ZHANG Xu-bin;XU Chun-jian;ZHOU Ming    2005, 5 (1): 97-102.   Abstract （1556）      PDF （198KB）（693）       Knowledge map    Save On the basis of the Bhatnagar Gross Krook equation, a new scheme for multi-component flow calculations between two closed surfaces of evaporation and condensation was developed. This model reveals the profiles of density, temperature, velocity and concentration of vapor in the space between evaporation surface and condensation surface. It was used to simulate the vapor behaviors of the dibutylphthalate dibutylsebacate (DBP-DBS) mixture system in the presence of an inert gas. The effects of inert gas pressure and construction parameters on evaporation efficiency and separation factor were discussed. Related Articles | Metrics Select Textural Fractal Dimension of Slag Metal Boundary in Top-blowing Converter with Water Modeling CHEN Ren;ZOU Zong-shu    2005, 5 (1): 103-106.   Abstract （2724）      PDF （118KB）（633）       Knowledge map    Save Based on the law of similarity, a top-blowing converter is simulated with water modeling. A digital camera is used to take pictures. Digital image processing is carried out with computer. The length of slag metal boundary in a top-blowing steelmaking converter is experimentally studied with fractal dimension theory, aiming to examine its variation with blowing parameters. The textural fractal dimensions and dimensionless length of the slag metal boundary are calculated from the mixing images under various blowing conditions. The result shows that the lance position, gas flowrate and slag quantity have great influence on the transition of texture fractal. Furthermore, gas flowrate is primary factor. Experimental relationships between the transition textural fractal dimension and the blowing parameters are obtained. Empirical formulae for calculating the dimensionless length and fractal dimension are discussed. The experiment proves that textural fractal dimension is important basis for estimating dimensionless length of the slag metal boundary. The fractal theory is one of effective ways used to quantitatively calculate the slag metal boundary. Related Articles | Metrics Select Research Advances in Process Integration ZHAO Yue-hong;WANG Shao-feng;WEN Hao;XU Zhi-hong    2005, 5 (1): 107-112.   Abstract （2760）      PDF （100KB）（902）       Knowledge map    Save Process integration, as a promising research field of process engineering, has been extensively studied in recent years. The latest academic progress in process integration is reviewed in this paper. Some new concepts and technologies of process integration, such as mass exchange network, waste minimization, cogeneration, industrial ecology and supply chain integration are described in detail, meanwhile the importance of developing and applying this technology in China is stressed. Related Articles | Metrics Select Particles Transport Velocity in a Moving-bed Column for Ion Exchange Resin LIANG Dong;JING Shan    2005, 5 (2): 113-118.   Abstract （1836）      PDF （361KB）（807）       Knowledge map    Save The particles transport velocity and influencing factors for a φ280 mm moving-bed column, which is possibly used in industry for removing 137Cs ions from the highly radioactive solution, are investigated. Experimental results show that the feeding rate of liquid into the moving-bed column, liquid rising velocity of riser and height of particles in the moving-bed column have important influence on particles transport velocity, and the reason is given to the system pressure balance. Based on the data, the dimensionless correlation has been obtained for particles transport velocity. Experimental results also show that the leakage rate of liquid through the solid-return pipe remains constant and the direction of liquid leakage is from riser to downer due to the relatively thin and long solid-return pipe. Related Articles | Metrics Select Experimental Study on Flow Characteristics of Catalyst in the Standpipe LUO Bao-lin;ZONG Xiang-rong;WANG Zhong-li;YANG Qi-ye    2005, 5 (2): 119-124.   Abstract （1750）      PDF （368KB）（796）       Knowledge map    Save Experimental study was conducted on flow characteristics of catalyst in a standpipe with φ108 mm×4 mm and height of 10 m. The axial profile of pressure and circulating rate of catalyst in the standpipe and the influence of auxiliary air on them were measured. The experimental results show that the gas-solid flow in the standpipe is comprised of both flow status of stripping gas at the down move-flow region with negative pressure gradient and holding gas at the down move-flow region with positive pressure gradient. The restrictive effect of the open-extent of discharge valve on solid circulating rate is obvious, and the increase of overall pressure drop in the holding gas section is more notable than that in the stripping gas section. Auxiliary air to the standpipe with suitable air volume and at appropriate entry position is possessed of marked function to increase pressure, and will change the profile of pressure in the standpipe. Based on the experimental results and analysis, the idea and principle about design of standpipe shape and dense-phase transportation of catalyst in the standpipe were presented. Related Articles | Metrics Select Preliminary Investigation on Interphase Mass Transfer in Agitated FANG Jing;YANG Chao;YU Geng-zhi;MAO Zai-sha    2005, 5 (2): 125-130.   Abstract （3285）      PDF （263KB）（1139）       Knowledge map    Save Volumetric mass transfer coefficients were determined for liquid-liquid-solid dispersion in a mechanically agitated baffled tank with internal diameter D=0.118 m. The effects of agitation speed (210～460 r/min), inert glass beads diameter (74～355 μm in size), type of impeller (Rushton, PTU, PTD), impeller-to-bottom distance (D/6, D/4, D/3), mass fraction of inert glass particles (<2%) on the mass transfer of typical liquid-liquid extraction system n-butanol-deionized water-succinic acid were examined. The data were collected on-line using a conductivity probe and processed with a PC computer. The mass transfer coefficients of liquid-liquid and liquid-liquid-solid systems were compared under the same operation conditions. It is revealed that the presence of a solid phase enhances the interphase mass transfer. The experimental results are discussed in light of hydrodynamics in stirred tanks. Related Articles | Metrics Select Numerical Simulation and Experimental Study on Mixing Characteristics of Stirred Bioreactor HONG Hou-sheng;ZHANG Qing-wen;WAN Hong-gui;OUYANG Ping-kai    2005, 5 (2): 131-134.   Abstract （2580）      PDF （420KB）（1437）       Knowledge map    Save By commercial CFD package CFX-4.4, mixing characteristics of stirred bioreactor were simulated and the mixing time variation under various operation conditions was investigated. The liquid mixing time was measured by means of detecting the concentration variety of [H+] with a pH probe. The deviation between simulation and experiment becomes smaller as the bioreactor volume is increased, and the error for 25 m3 bioreactor is less than 11.6%. Related Articles | Metrics Select Numerical Simulation of Fluid Flow and Optimization on Structure of Air-agitated Seed Precipitation Tank YAN Hong-jie;ZHOU Ping;ZHOU Jie-min;LU Zi-jian;ZHOU Huai-min    2005, 5 (2): 135-138.   Abstract （1782）      PDF （285KB）（851）       Knowledge map    Save Air-agitated seed precipitation tank is a key facility for the industrial production of alumina and there exist many defects, such as scaling, liquid short-circuiting and so on. In order to overcome these defects, three-dimensional flow field in the tank with different structures is calculated numerically using CFD software. Euler/Euler approach is used to study the effect of structure on the flow field in the tank. Two-fluid model and multi-block gird are adopted in the simulation. The results discussed in this paper are well consistent with the practical situations. The flow field is improved obviously and the rate of scaling is reduced in the optimized tank. With using a gathering sill, the problem of short-circuiting, which always appeared in the upper of the tank, is controlled very well. Related Articles | Metrics Select Influence of Resdistributors and Baffles on Hydrodynamics of Slurry Bubble Column Reactors SUN Shu-lan;LIU Chang-jian;WEI Wei-sheng;BAO Xiao-jun    2005, 5 (2): 139-143.   Abstract （1542）      PDF （366KB）（659）       Knowledge map    Save The effects of redistributors and baffles with different geometry on average gas holdup, solid holdup and gas axial profiles of an air-water-quartz sand three-phase system were investigated in a slurry bubble column reactor of 0.1 m in I.D. and 2.0 m in height. The results showed that the redistributors could significantly increase the average gas holdup in the reactor, but baffles had no obvious effect. The increase in average gas holdup by introducing the redistributors was found to depend upon the hole size and opening fraction of the perforated redistributors. It was also found that both redistributors and baffles could improve the uniformity of the axial profiles of gas and solid holdup with only small increase in pressure drop. Based on the correlation due to Smith, an empirical correlation for the average gas holdup in slurry bubble columns with redistributor was obtained. Related Articles | Metrics Select Pervaporation of Ethanol/Water and Acetic Acid/Water Mixtures through PDMS Membranes LI Hao;YU Jiang;LIU Hui-zhou    2005, 5 (2): 144-147.   Abstract （1583）      PDF （249KB）（739）       Knowledge map    Save The effects of feed concentration and feed temperature on the flux and selectivity of polydimethylsiloxane (PDMS) pervaporation membrane for separating ethanol and acetic acid from ethanol/water and acetic acid/water mixtures were investigated. The swelling properties of PDMS membrane in ethanol and acetic acid were also examined for exploring the possible separation mechanism in the pervaporation process. The results indicated that pervaporation was quite different for ethanol and acetic acid. Compared with the preferential pervaporation of ethanol through PDMS, the low diffusion rate of acetic acid in PDMS membrane was observed, which made water pass through PDMS membrane prior to acetic acid if the operation temperature was lower than 60℃. Related Articles | Metrics Select Extraction of Phenols with Hydrophobic Ionic Liquids LI Xian;ZHANG Suo-jiang;ZHANG Jian-min;CHEN Yu-huan;ZHANG Yan-qiang;SUN Ning    2005, 5 (2): 148-151.   Abstract （1770）      PDF （188KB）（871）       Knowledge map    Save Hydrophobic ionic liquids, 1-butyl-3-methylimidazolium hexfluorophosphate ([bmim]PF6) and 1-decatyl-3-methylimid- azolium hexfluorophosphate ([dmim]PF6), were used for extracting phenols from aqueous solutions. The distribution coefficients of phenols between water and ionic liquids were determined. The results showed that the distribution coefficients of phenols between water and ionic liquids were on the same order as that between water and conventional organic solvents, and the extraction efficiency was dependent on temperature and the length of alkyl chain on the imidazole of ionic liquids. Ionic liquids show the potential to replace organic solvents for extracting phenols from wastewater, due to its unique characteristics. Related Articles | Metrics Select Study of the Gelling Process for the Preparation of Tin Oxide Materials Based on Tin Tetrabutoxide HUANG Rui-an;HOU Li-song;ZHAO Qi-tao;REN Shu-hua    2005, 5 (2): 152-156.   Abstract （1771）      PDF （268KB）（565）       Knowledge map    Save The gelling process in the preparation of tin oxide materials based on tin tetrabutoxide is studied. Sn(OBun)4 modified by two moles of acetylacetone (AcAc) has a stable six-member ring structure and is less susceptive to water. In a system with a lower molar ratio of acetylacetone to Sn(OBun)4 ([AcAc]/[Sn(OBun)4]<2.0) or a larger portion of water ([H2O]/[Sn(OBun)4]>2.5), colloidal suspension or white precipitation will take place. A system with molar ratios of both acetylacetone to Sn(OBun)4 and water to Sn(OBun)4 at 2.0 is transparent and olivaceous sol. As catalysts, hydrofluoric, hydrochloric, hydrobromic and acetic acids, and ammonia all accelerate the hydrolysis and condensation of Sn(OBun)4 during the sol-gel process. Light scattering measurement indicates that cluster size distribution in the sol system undergoes gradual broadening during the sol-gel transition. Related Articles | Metrics Select Experimental Study on Co-gasifying of Natural Gas and Coal in a Fixed Bed for Preparation of Synthesis Gas SONG Xue-ping;GUO Zhan-cheng    2005, 5 (2): 157-161.   Abstract （1427）      PDF （220KB）（662）       Knowledge map    Save The reaction process of natural gas and coal was investigated using a fixed-bed reactor to model the furnace for preparing synthesis gas. Experimental results indicated that oxidation of methane and carbon occurred simultaneously in the lower zone close to the furnace bottom and O2 was used up. Pyrolysis of methane and reduction of CO2 and steam took place during the rising of synthesis gas. The whole reaction system for preparation of synthesis gas nearly reached equilibrium while the synthesis gas left the outlet of furnace. Related Articles | Metrics Select Synthesis of a Novel Superabsorbent Resin Based on Acrylic Acid and Maleic Anhydride WANG Li-yong;REN Tian-rui    2005, 5 (2): 162-165.   Abstract （1662）      PDF （308KB）（837）       Knowledge map    Save A kind of novel copolymer superabsorbent resin based on the monomers[maleic anhydride (MA), acrylic acid (AA) and its salts] was prepared by solution polymerization using ammonium persulfate (APS) as initiator, N,N-methylenebisacrylamide (MBA) and glycerine as cross-linking agents. Effects of process parameters such as the concentrations of monomers, cross-linker, initiator and degree of ammoniation of maleic anhydride on the absorbency of superabsorbent resin were discussed. Under the optimal conditions, the absorbency of water from distilled water and 0.9% NaCl solution was 1689 g/g and 115 g/g, respectively. Related Articles | Metrics Select Manufacture of Calcium Chromate from Decomposition of Calcium Carbonate in Aqueous Sodium Dichromate Solution WANG Tian-gui;LI Zuo-hu    2005, 5 (2): 166-169.   Abstract （2860）      PDF （223KB）（760）       Knowledge map    Save There are various processes known for production of calcium chromate, which suffer from inherent disadvantages such as poor quality and severe pollution. A novel process for the manufacture of calcium chromate was presented in this paper. It is shown that calcium carbonate can be decomposed in aqueous sodium dichromate solution and transformed to calcium chromate at ambient pressure and boiling temperature. Both reaction temperature and concentration of sodium dichromate are the main factors controlling the decomposition of calcium carbonate. Under the conditions of the concentration of sodium dichromate≥60% and the molar ratio of sodium dichromate to calcium carbonate≥1.05:1, the purity of calcium chromate can reach 99.5% and the yield approaches to 100%. The carbon dioxide and aqueous sodium chromate solution produced during the decomposition of calcium carbonate can be recycled and no waste is discharged. Related Articles | Metrics Select Properties of Li4Ti5O12 Prepared with Amorphous TiO2 YANG Jian-wen;ZHONG Hui;ZHONG Hai-yun;DAI Yan-yang;ZHAO Xuan    2005, 5 (2): 170-174.   Abstract （2776）      PDF （300KB）（756）       Knowledge map    Save Micron-sized powder Li4Ti5O12 was prepared in a single-step solid state reaction involving amorphous TiO2 and Li2CO3, and its microcosmic characteristics and electrochemical behavior were studied. X-ray diffraction analysis indicated that the products of Li4Ti5O12 were of single cube-spinel phase structure with good crystallization. The laser particle size and scanning electron microscopy analysis showed uniformly distributed gravel Li4Ti5O12 particles with average grain size of 2.66 μm. The lithium cell, consisting of Li4Ti5O12 cathode and lithium anode, displayed a wide discharge/charge plateau at 1.5 V, a very stable characteristic for Li ion insertion and emission. The first discharge and cycle specific capacitance were 180 and 150 mA·h/g at 0.1 C current respectively. AC impedance spectra of the Li/Li4Ti5O12 cell at charge/discharge potentials showed that electrochemical impedance was possibly influenced by the corresponding conductivity at the Li+ insertion extend, and the slopes of Warburg impedance lines were correlated with Li4Ti5O12 charge-states. Related Articles | Metrics Select Effect of Heat Treatment on the Microstructure of Glass Ceramic from Boron Mud SHI Pei-yang;JIANG Mao-fa;LIU Cheng-jun;DENG Jiang-ning;ZHU Ming-wei    2005, 5 (2): 175-178.   Abstract （1559）      PDF （451KB）（644）       Knowledge map    Save Glass-ceramic was prepared from raw materials mainly containing boron mud, and the crystallizability of glass ceramic of CaO-MgO-Al2O3-SiO2 system was studied by means of DTA, XRD and SEM. Effects of sintering time and crystallizing time on the microstructure of glass ceramic were also analyzed. The results show that the main crystalline phase of the glass ceramic is hedenbergite, while the subordinate crystalline phases are spinel and olivine, its grain sizes are about 2~5 μm, with dendrite, columnar crystal and bulk crystal existing in aggregation, and the optimum sintering time and crystallizing time are 4 and 4 h, respectively. Related Articles | Metrics Select Modelling and Optimization Based on the Molecular Matrix for the Overall Refinery Operation ZHOU Qi-hong;HU Shan-ying;CHEN Ding-jiang;YU Zhi-wu    2005, 5 (2): 179-182.   Abstract （2672）      PDF （234KB）（701）       Knowledge map    Save To complicated refining processes and stream components, molecular matrices are used to express refining stream compositions. Process models based on molecular matrices are built for catalytic reforming unit, naphtha hydro-treating unit, gasoline stabilizer unit and gasoline blending unit. Molecular compositions can be obtained from stream bulk properties with the conversion model and vice versa. The process models on the basis of molecular matrices can not only give out more detailed molecular information, but also form a common component base for the traditional pseudo-component models in the distillation processes and lumped models in the reaction processes, which makes it possible to integrate multi-process models into an overall plant modeling. Related Articles | Metrics page Page 1 of 4 Total 152 records First page Prev page Next page Last page