Volumn Content

The Chinese Journal of Process Engineering 2011 Vol.11 Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Turbulent Characteristics of a Novel Circulating Jet Mixer YU Yan-fang WU Jian-hua MENG Hui-bo    2011, 11 (1): 1-8.   Abstract （1964）      PDF （620KB）（451）       Knowledge map    Save SST k-w turbulence model was employed to simulate the turbulent flow field of a novel circulating jet mixer. The similarity of confined zone jet and the decay of jet axial velocity at various baffle lengths were carried out. The decay of dimensionless jet axial velocity by simulation was in good accordance with theoretical curve for free turbulent jet. The fluid zone in the jet mixer was divided into four sub-regions based on the three-dimension velocities. The fluid circulating flow in the novel jet mixer was studied by vorticity and the average vorticity áw? with different axial positions and phase planes. The results show that the maximum value of áw? is 11.22 at z/H=0.25. áw? is positive at qp<20o, while at other qp it is negative. The maximum value of áw? is 27.22 which is located at qp=16o, and the minimum value of áw? is -100.66 at qp=20o. The simulation result of shear rate reveals that the larger value is located in the trailing vortex. The factors for enhancing the mixing effect are put forward. Related Articles | Metrics Select Effect of Sieve Plate Structure on Gas Cap Height and Local Gas Holdup in a Multistage Bubble Column Reactor QIN Ling JIN Hai-bo; YANG Suo-he HE Guang-xiang ZHU Jian-hua    2011, 11 (1): 9-14.   Abstract （1158）      PDF （245KB）（391）       Knowledge map    Save The effect of sieve plate structure on the gas cap height and local gas holdup in a f300 mm multistage bubble column was studied using differential-pressure method and double-sensor conductivity probe. The experimental results show that the gas cap height increases with the increase of superficial gas velocity, ug, and decrease of opening area of the sieve plates. The gas cap height increases from 0.01 to 0.06 m while ug increases from 0.04 to 0.24 m/s. Moreover, the radial distribution of gas holdup in the reactor is similar to that in a regular bubble column. The average gas holdups above and under the plate increase with the increase of ug. For the axial distribution of gas holdups, when ug is about 0.027 m/s, the gas holdups above and under the plate are all around 0.05. But when ug becomes 0.11 m/s, the gas holdup under the plate is about 0.3~0.35, which is much higher than the one above plate with around 0.25~0.3. Related Articles | Metrics Select Numerical Simulation of Mixing Performance in Seed Precipitation Tank with an Improved Intermig Impeller ZHAO Hong-liang ZHANG Ting-an ZHANG Chao LIU Yan ZHAO Qiu-yue WANG Shu-chan DOU Zhi-he    2011, 11 (1): 15-19.   Abstract （1236）      PDF （779KB）（501）       Knowledge map    Save Seed precipitation tank with a new-style improved Intermig impeller was numerically simulated by using the commercial software Fluent 12.0 on parallel computing graphic workstation. The suspension of Al(OH)3 particles and power consumption in the alumina seed precipitator under different conditions of the impeller off-bottom clearance height (C) and blade diameter (D) were numerically simulated by using realizable k-ε turbulence, Eulerian-Eulerian multiphase and multi-reference frame rotating models. The numerical simulation results showed that at a constant rotate speed, enlarging D was good for suspension of Al(OH)3 particles, but bigger D resulted in more power consumption. The optimal value of D/T was 0.6, T was the tank diameter. Too big or too small C was not conducive to the suspension of Al(OH)3 particles, and C had little effect on the stirring power. The optimal value of C/D was 0.55. Related Articles | Metrics Select Numerical Simulation of Three-phase Flow in an Oxygen Top-blown Convertor DONG Kai ZHU Rong; HE Chun-lai; WEI Xin-yan LIU Fu-hai    2011, 11 (1): 20-25.   Abstract （1117）      PDF （1065KB）（498）       Knowledge map    Save The impingement of supersonic oxygen jets on molten steel and slag in an 85 t top-blown convertor bath was studied and the flow field of molten bath analyzed. The results show that with the oxygen lance rising, the diameters of cavities created by jets in the molten slag and steel increase, whilst the depths decrease. With the lance height rising from 1.2 to 1.8 m, the diameter of cavity in the molten steel increases from 1.359 to 1.566 m, whilst the depth decreases from 0.187 to 0.157 m. At the same time, the maximum velocity of liquid steel decreases from 0.48 to 0.27 m/s 0.2 m under the molten steel surface, whilst the maximum velocity of liquid steel increases from 0.06 to 0.09 m/s 0.8 m under the molten steel surface. High lance position has a positive effect on the homogeneous distribution of liquid steel velocity. Related Articles | Metrics Select Mathematical Simulation for Velocity and Temperature Fields of Molten Steel in a 5-strand Tundish ZHONG Liang-cai WANG Ming-an ZHOU Xiao-bin LIU Le-dong TENG Li-hong    2011, 11 (1): 26-30.   Abstract （955）      PDF （480KB）（511）       Knowledge map    Save Velocity and temperature fields of molten steel in a 5-strand tundish with different baffles were investigated by mathematical simulation. The calculation results showed that liquid steel directly moved to the outlets of tundish with original baffle after it flowed out from the holes in the baffle, and there was a large dead zone above the first outlet. Temperature distribution in the original tundish configuration was not uniform. The temperature difference between high temperature zone and low one on the liquid surface outside the pouring zone was 10.7℃ and the temperature difference among the outlets of the tundish 4℃. With the improved baffle, molten steel mainly flowed in the upper layer of tundish bath after it departed from the holes in the baffle. The flowing route of liquid steel became long and dead zone small in the tundish. Temperature field of liquid steel turned uniform and temperature of steel flowing out from the tundish outlets was the same. Related Articles | Metrics Select Simulation of Slag Splashing in a 210 t Top-Bottom Combined Blowing Converter LIAO Guang-fu CHEN Min LI Guang-qiang ZHANG Hao XIAO Zun-hu SU Feng-guang    2011, 11 (1): 31-35.   Abstract （1316）      PDF （378KB）（453）       Knowledge map    Save Simulation experiments with water as slag on slag splashing in a 210 t top-bottom combined blowing converter were carried out. By measuring the amount of water taken as slag splashed onto the lining, the effects of operating parameters on slag splashing were examined, the optimal parameters were obtained as follows: top-blown gas flow rate was 50000 Nm3/h, lance height around 3680 mm, nozzle angle 15°, amount of slag remained for splashing 21 t, layout A1 of bottom tuyeres and bottom flow rate about 900 Nm3/h. Related Articles | Metrics Select Water Model Study on a 210 t Top-Bottom Combined Blown Converter CHEN Min LIAO Guang-fu LI Guang-qiang YUAN Gang XIAO Zun-hu SU Feng-guang    2011, 11 (1): 36-39.   Abstract （2011）      PDF （235KB）（484）       Knowledge map    Save The impacts of bottom tuyeres layout, flowrate of top blowing, lance height and other factors on mixing time, penetrating depth and cavity diameter in a 210 t top-bottom combined blown converter were studied using water model. The effects of different factors on the mixing time, penetrating depth and cavity diameter were not consistent. The operating parameters of the shortest mixing time were obtained as follow: layout A3 of bottom tuyeres, flowrate of top blowing 50000 Nm3/h, flowrate of bottom blowing 1000 Nm3/h, lance height 1700 mm, and nozzle angle 17°. Related Articles | Metrics Select Mathematical Modeling of Fluid Flow in an AOD Converter Bath under Conditions of Combined Side and Top Blowing: Application of the Model to Combined Side and Top Blowing Process and Results WEI Ji-he HE Yuan SHI Guo-min    2011, 11 (1): 40-43.   Abstract （1937）      PDF （343KB）（400）       Knowledge map    Save The fluid flows in the bath of a 120 t AOD converter and its water model with a 1/4 linear scale in the combined side and top blowing have been treated and analyzed from the superposition of the computed results of those during the simple side and top blowing processes respectively by the side and top blowing components of the mathematical model developed for the molten steel flow in an AOD bath under the conditions of combined blowing. The results demonstrate that the mathematical model can be used to simulate the fluid flow in an AOD bath with the combined blowing. The liquid flow in the bath with the combined blowing results from the gas side blowing streams under the influence of a gas top blowing jet, the gas side streams play a governing role for it, and the liquid is equally in vigorous stirring and circulatory motion during the combined blowing also without obvious dead zone in the whole bath. Compared with those in a simple side blowing, the impinging of a gas top blowing jet does not change the essential features of gas agitation and fluid flow in the bath, but can make the local flow pattern of the liquid vary evidently. The changes in the angle between each tuyere and the tuyere number have similarly not altered the basic characteristics and patterns of gas stirring and liquid flow and turbulent kinetic energy distribution in the bath. However, at a given tuyere number and gas side blowing rate or a given angular separation between each tuyere and gas side blowing rate, the variation of the number or the angle can change locally them. Using 6 tuyeres with 27° for blowing can reach more uniform flow field and turbulent energy distribution of the liquid in the AOD bath with the combined blowing than that taking 7 tuyeres with 18° or 22.5° and 6 tuyeres with 22.5°. Related Articles | Metrics Select Removal of Fluoride from Aqueous Solution by Modified Al-Zr Pillared Bentonite LONG Min TANG Yan-kui TONG Zhang-fa LIANG Da-wen    2011, 11 (1): 44-49.   Abstract （2108）      PDF （469KB）（382）       Knowledge map    Save Microwave-aided synthesized Al-Zr pillared bentonite (MAZPB) was applied to remove fluoride from aqueous solution. MAZPB was characterized by SEM and XRD. The influences of pH value, adsorbent dose and presence of other anions on fluoride adsorption on MAZPB were investigated. The results showed that MAZPB efficiently adsorbed F- in a wide pH range (3.5~10), and its removal rate remained above 89%. The presence of other ions such as ferric ion and carbonate affected the adsorption of fluoride significantly, indicating the selective nature of the adsorbent. The kinetic parameters of the adsorption showed that the adsorption kinetics followed a pseudo-second-order model. The Freundlich model yielded a much better fitting than the Langmuir model, indicating that the physical adsorption was predominant. Used MAZPB could be regenerated by alum, and the removal rate of fluoride reached 81.93%. Related Articles | Metrics Select Experimental Study on Rational Technology of Dephosphorization Pretreatment for High Phosphorus Content Hot Iron ZHOU Dong-jin BI Xue-gong WU Jie HUANG Zhi-cheng WEN Zhi-jun XIONG Wei LI Yong-bo JIN Yan    2011, 11 (1): 50-55.   Abstract （1134）      PDF （238KB）（367）       Knowledge map    Save The effects of oxygen supply method and flux consumption on temperature drop during the dephosphorization process and efficiency of high phosphorus hot iron with about 0.6%(w) phosphorus were studied in laboratory. The results revealed that by using pure solid form oxygen the slag volume was big, temperature drop great, and phosphorus oxidation rate was fast, the reaction was basically completed for 2 min with dephosphorization rate up to 89.45% while by partially replacing solid form oxygen with gaseous oxygen, slag volume was smaller, temperature drop less, but the treatment time was longer and the final dephosphorization efficiency was negatively affected. Dephosphorization rate was only 51.13% when gaseous oxygen content reached 75%. The rational dephosphorization pretreatment technology for high phosphorus hot iron should be close control of solid dephosphorization agent consumption, replacement of solid form oxygen with proper amount of gaseous oxygen at about 25% and control of shorter pretreatment time. Related Articles | Metrics Select Recovery of Valuable Metals by Leaching of Roasted Jarosite Residue XUE Pei-yi JU Shao-hua ZHANG Yi-fei WANG Xin-wen    2011, 11 (1): 56-60.   Abstract （1258）      PDF （267KB）（394）       Knowledge map    Save A new process of roasting-ammonium chloride leaching-alkali leaching for recovery of valuable metals and iron in jarosite residue generated during zinc hydrometallurgy was studied by experiment. After roasting of jarosite at 650℃ for 1 h, the main phase of KFe3(SO4)2(OH)6 containing Pb and Zn was decomposed into Fe2O3, ZnSO4 and PbSO4. When the roasted jarosite residue was leached by 5 times with aqueous solution of 6 mol/L ammonium chloride at 105℃ for 2 h, over 95% of Zn, Pb and Cd in the jarosite was leached and the iron content was raised from 22% to 40%. The leached residue was further leached with 23.08%(w) NaOH solution at 160℃ for 1 h, Fe content in the final residue was 54%, which could be used as qualified iron concentrate. Related Articles | Metrics Select Extraction Kinetics of Mn(II) by the Sodium Salt of P204 XING Peng WANG Chen-yan    2011, 11 (1): 61-64.   Abstract （2102）      PDF （190KB）（442）       Knowledge map    Save The extraction kinetics of Mn(II) from sulfate medium by the sodium salt of P204 (Na-P204) was studied using a modified Lewis cell. The effects of stirring speed, temperature, interfacial area, and concentrations of Na-P204 and of Mn(II) on the extraction rate of Mn(II) were investigated. The extraction rate increased with increasing of stirring speed, temperature and interfacial area. The extraction rate remained constant with further increase of stirring speed when it was above 104 r/min. The apparent activation energy of Mn(II) extraction by Na-P204 was 23.50 kJ/mol. The rate determining step of Mn(II) extraction by Na-P204 was chemical reaction at the interface. The extraction rate was proportional to the concentrations of Mn(II) in the aqueous phase and Na-P204 in the organic phase. The effect of concentration of Mn(II) on the extraction rate is less pronounced than that of Na-P204. The extraction rate could be represented by the following equation under the conditions of 18℃ and interfacial area 21.19 cm2: r=2.06′10-2[NaA](O)1.35[Mn2+]0.41. Related Articles | Metrics Select Study on Smelting Reduction Ironmaking of Copper Slag LI Lei HU Jian-hang WANG Hua    2011, 11 (1): 65-71.   Abstract （1312）      PDF （246KB）（600）       Knowledge map    Save According to the mechanism of smelting reduction, the process of smelting reduction ironmaking from copper slag was studied. The effects of slag basicity, holding temperature, holding time and CaF2 addition (mass ratio of CaF2 to CaO) on the iron yield and sulfur, phosphorus removal efficiency from the molten iron were examined. XRD analysis results indicated that the iron phases in the copper residue were mainly 2FeO×SiO2 and Fe3O4. In N2 atmosphere, the iron yield of 89.28%, sulfur content in hot metal of 0.039%, and phosphorus content of 0.087% were obtained in the conditions of basicity 1.6, holding time 30 min at 1575℃ and CaF2/CaO 10%. The study worked out the problem of high sulfur content in the iron from smelting reduction. Related Articles | Metrics Select Thermodynamic Analysis and Experimental Study on Alkali-roasting Treatment of Limonitic Laterite Ore with Sodium Carbonate GUO Qiang QU Jing-kui HAN Bing-bing WEI Guang-ji QI Tao    2011, 11 (1): 72-78.   Abstract （1283）      PDF （320KB）（416）       Knowledge map    Save Thermodynamic analysis and experimental study on the treatment of limonitic laterite ore by sodium carbonate roasting have been performed. Thermodynamic analysis results show that in the range of 500~1500 K, the decomposition of goethite and gibbsite can take place easily whereas chromite is decomposed spontaneously at high temperature. The formation reaction of sodium chromate during the alkali-roasting treatment process is feasible, and the thermodynamic trend FeO×Cr2O3>Cr2O3. Increasing the roasting temperature increases the leaching rate of Cr. And high temperature favors the production of sodium aluminate and sodium silicate, and increasing the roasting temperature improves the leaching rates of Al and Si in 1123~1273 K. However, with the further increase of temperature, the preferential generation of sodium alumino-silicate precipitates by the reaction between sodium aluminate and silicon dioxide can result in loss of soluble Al, Si, and Na. Experimental results show that the leaching rates of Cr, Al, and Si are 99.7%, 82.8%, and 40.4%, respectively, under the roasting temperature of 1273 K, roasting time of 2 h, and mass ratio of Na2CO3 t ore of 0.6. Related Articles | Metrics Select Effect of Pulsed Electric Field on Solidification Process of Fe-C-P System Alloy HONG Peng WANG Hai-chuan LI Xin LI Jie LIAO Zhi-you QIAN Zhang-xiu    2011, 11 (1): 79-84.   Abstract （1136）      PDF （614KB）（380）       Knowledge map    Save Imposing of pulsed electric field can effectively reduce the grain boundary segregation and improve the solidification structure Fe-C-P alloy during solidification of its melt, but it can also cause the migration and redistribution of elements, in which element P migrates from the anode to the cathode, the migration law of element C is similar to P. As the voltage increases, the standard deviation of P segregation is decreased from 1.67 to 1.26, and that of C from 1.03 to 0.65. After processing, the inclusions are mainly distributed in the central region, but phosphorus-containing inclusions can not be observed, there is a small amount of MnS and Al2O3 inclusions. Related Articles | Metrics Select Assessment of Oxygen Concentration Unit from Measured Oxygen Activity by Oxygen Sensor Based on Metallurgical Thermodynamics YANG Xue-min SHI Cheng-bin ZHANG Meng LI Dao-ming    2011, 11 (1): 85-90.   Abstract （1174）      PDF （207KB）（355）       Knowledge map    Save Taking Celox￠s oxygen sensor from Heraeus Electro-Nite Shanghai Company Limited as an example, the measured oxygen activity by the sensor has been compared with the reported oxygen activity from literatures, the calculated oxygen activity of aluminum-killed molten steel during a 210 t LF refining process based on [Al]-[O] equilibrium and the calculated oxygen activity of molten steel at steelmaking end-point in an 80 t top-bottom combined blown converter based on [C]-[O] equilibrium. The comparison results show that the measured oxygen activity from Celox oxygen sensor as a representative of commercial oxygen sensors is based on 1%(w) solution as standard state and one part per million, [10-6 O] as oxygen concentration unit, but not 1%(w), [%O] as oxygen concentration unit. Therefore, the magnitude of measured oxygen activity by the sensor must be treated as 10-4, rather than the displayed 10-6 in the display device of Celox oxygen sensor under the condition of applying 1%(w), [%O] as oxygen concentration unit. Related Articles | Metrics Select Experimental Investigation on Direct Reduction of Iron Ore Powder by Pulverized Coal in a Circulating Fluidized Bed FAN Li-juan; LU Qing-gang NA Yong-jie YU Kuang-shi;    2011, 11 (1): 91-96.   Abstract （1147）      PDF （599KB）（371）       Knowledge map    Save The effect of reaction temperature on the reduction degree and microscopic structure of reduced products, and the reduction process of iron ore powder by Datong pulverized coal in nitrogen was examined in a circulating fluidized bed in the reaction temperature range from 800℃ to 950℃. The metallization and reduction degrees of reduced products increase as the reaction temperature increases. There is a larger increase at 800~850℃, moderate increase at 850~900℃ and the greater increase at 900~950℃. The metallization and reduction degrees can reach 63% and 87%, respectively, when the reaction temperature ascends to 950℃. Compared with the raw iron ore powder, the specific surface area and total pore volume of reduced products are increased at 800℃, while reduced at the other temperatures, the corresponding variation of the average pore size parameters is opposite. Related Articles | Metrics Select Experimental Study on Assimilation of Iron Ores at Home and Abroad ZHANG Jian-liang SU Bu-xin CHE Xiao-mei LIN Xiang-hai KONG De-en GUO Hong-wei    2011, 11 (1): 97-102.   Abstract （1195）      PDF （245KB）（738）       Knowledge map    Save Assimilation of 7 kinds of iron ores from Australia, Brazil, India, South Africa and China was evaluated and analyzed. The results show that the ores with different types or from different places are apparently different in assimilation. Among them, the assimilation of India ore is the highest, of which the lowest assimilation temperature is 1235℃, the content of SiO2 9.52%, and content of crystallized water 5.67%; except these, the ore is hematite, showing as crumbly particles. The lowest assimilation ore is South Africa ore, of which the lowest assimilation temperature is 1355℃, the content of MgO up to 2.37%, and content of crystallized water 0.05%, except these, the ore is construction-compact magnetite. The assimilation of the ores has negative correlation with MgO content and binary basicity, while it has positive correlation with porosity and the content of SiO2, Al2O3, and crystallized water. The iron ores with small crystalline size and microstructure looseness have relatively higher assimilation. Related Articles | Metrics Select Study on Technological Conditions in Preparation of Anhydrous Cerium Chloride WU Jin-xiu LI Mei LIU Zhao-gang HU Yan-hong WANG Mi-tang    2011, 11 (1): 103-106.   Abstract （1350）      PDF （275KB）（435）       Knowledge map    Save Technological conditions in preparation of high purity anhydrous cerium chloride with ammonium chloride as chlorinating agent to chlorinate cerium oxide in argon atmosphere were studied. The reaction temperature and time, and dosing ratio of reactants by orthogonal experiments for optimization of the preparation conditions were examined, and its product was characterized by XRD. The results showed that by chlorinating cerium oxide for 30 min with ammonium chloride dosage in a molar ratio of n(NH4Cl):n(CeCl4)= 12:1 at 300℃, the chlorinating rate of oxide reached 99.6%, the impurity in the anhydrous cerium chloride product was less than 5%. Related Articles | Metrics Select Preparation of Hollow Silica Microspheres with Synechocystis sp. PCC 6803 as Bio-template ZHANG Bo REN Tian-rui WU Qing-hai WANG Quan-xi FENG Hao    2011, 11 (1): 107-112.   Abstract （1327）      PDF （1020KB）（357）       Knowledge map    Save Silica particles with different morphologies were prepared using cyanobacteria Synechocystis sp. PCC 6803 as a biotemplate via a sol-gel route. The Synechocystis sp. PCC 6803 and as-prepared silica were characterized. The reaction conditions of selective synthesis of monodisperse silica and hollow silica microspheres were established. The formation mechanism of different morphologies was discussed. The results indicated that the silica microspheres had an amorphous structure with an average diameter of 1.5 mm, and retained the original morphology of the cells. SiO2 nanoparticles could be uniformly coated on the surface of cells to form the hollow SiO2 microspheres, which had uniform wall thickness and could maintain the original morphology of cells. It was confirmed that the formation mechanisms of SiO2 hollow spheres and SiO2 microparticles were based on the difference between adsorption and penetration. Related Articles | Metrics Select Production of Coenzyme Q10 in Fed-batch Fermentation by Agrobacterium tumefaciens JIN Sai; XU Jian; ZHANG Liang; DING Chong-yang; SHI Gui-yang;    2011, 11 (1): 113-116.   Abstract （1149）      PDF （223KB）（408）       Knowledge map    Save The production of coenzyme Q10 by Agrobacterium tumefaciens Q14 was studied under fed-batch fermentation by adding restrictive nutrient substances in a 15 L fermentor. The best process of fed-batch fermentation was obtained by stepwise optimization in order to maintain glucose concentration between 5 and 15 g/L and phosphorus concentration between 50 and 120 mmol/L. 5%(j) fresh medium was added at 30 and 50 h, respectively, to satisfy the growth of cells. The results showed that the fermentation period was 84 h, a highest biomass of 87.2 g/L, coenzyme Q10 production of 2166.2 mg/L and productivity 25.9 mg/(L×h) which increased 7.8 times compared with batch fermentation. Related Articles | Metrics Select Preparation of Nano-TiO2/Attapuleite Composite and Its Photocatalytic Kinetics LIU Liang LU Jun LI Yun LIU Jia-qin WU Yu-cheng    2011, 11 (1): 117-123.   Abstract （1211）      PDF （732KB）（402）       Knowledge map    Save XRD, HRTEM, EDS and SEM were used to analyze the formation of nano-TiO2/attapulgite photocatalytic composite prepared by sol-gel method. XRD analysis showed that the composite was the mixture of anatase and rutile. HRTEM and SEM images showed that a uniform layer of TiO2 particles was loaded on the surface of attapulgite. The effects of calcination temperature, dosage of catalyst and adsorption properties on the photocatalytic properties of the composite were examined. The results showed that the grain size of TiO2 prepared at 600℃ was 16 nm and the phase content of anatase 87%. The composite had a stronger adsorption to methyl orange, and the adsorption equilibrium constant Ka=0.00896 L/mg. The kinetic equations of photocatalysis were in accord with Langmnir-Hinshelwood model, second-order kinetic equations could describe the degradation well and photocatalytic kinetic equation was lnCt+0.00896Ct=0.418-0.0197t. Related Articles | Metrics Select Influence of Heat Treatment on Microstructures and Properties of Nanosized Zirconia Powder and Coating YAO Xing-he; ZHU Yong-ping ZHANG Wei-gang    2011, 11 (1): 124-130.   Abstract （1255）      PDF （782KB）（416）       Knowledge map    Save The effects of high-temperature sintering, plasma torch and plasma flow heat treatments on the properties of ZrO2-8%mol Y2O3 (8YSZ) spherical powder and plasma sprayed coating were investigated. The results show that the plasma sprayed coating derived from plasma torch treated powder of 8YSZ has the highest bonding strength of 25 MPa and the best thermal shock resistance of 41 thermal cycles which is under water cooling after treatment at 1200℃ for 5 min. The coating fabricated by plasma flow treated 8YSZ has very low bonding strength of 11 MPa and poor thermal shock resistance of 17 thermal cycles. The coating prepared by sintering treated 8YSZ relies on the temperature and time of treatment, and the best mechanical properties are obtained when 8YSZ powder is treated at 1200℃ for 2 h, the average is 21 MPa and 38 thermal cycles. Related Articles | Metrics Select Crystallization Process of AlOOH Nano-particles with Different Shapes in Hydrothermal Systems HAO Bao-hong FANG Ke-ming    2011, 11 (1): 131-136.   Abstract （1214）      PDF （1014KB）（473）       Knowledge map    Save The model of growth unit was established for synthesis of AlOOH in hydrothermal systems, and the transfer process of growth unit deduced. The crystallization process of substances was analyzed from the angle of motion of growth units for the first time. The influential mechanisms of different hydrothermal environment systems on crystallization process and final morphology of heteromorphic AlOOH particles were discovered from the perspective of atomic aggregates. Emphasis was focused on the mechanisms of growth unit at various pH values in acidic medium, and characteristics of Al3+ tripolymers, ([Al3(OH)4(OH2)9]5+, [Al3(OH)5(OH2)8]4+ and [Al3(OH)6(OH2)7]3+) of nano-AlOOH. The formation process of the aggregates determined by various coordinate bonds of Al3+ tripolymers and the essence of oriented growth of AlOOH were discovered. The established model was directly proved with the experimental samples. Furthermore, the existence of polymers and motion of growth unit were proved right by means of detecting the infrared spectrogram. Various pH values determine different growth units, different growth units determines diverse successive transfer process, and finally determines one-dimensionally oriented growth of the crystal into different morphologies. Related Articles | Metrics Select Preparation of Nano-Al2O3 Particles via H2/Air Flame Synthesis and Their Dispersion Performance DING Hong-qiu; HU Yan-jie LI Chun-zhong    2011, 11 (1): 137-142.   Abstract （1164）      PDF （1020KB）（436）       Knowledge map    Save Nano-Al2O3 particles were prepared via H2/air flame synthesis in a multi-jet reactor with anhydrous AlCl3 as precursor, the morphology, structure, crystallinity, size and specific surface area of the prepared nanoparticles were investigated, and the influences of flame configuration and maximum temperature in the reaction zone on their properties characterized. The results showed that the size of particles increased with the flame temperature increasing, and their morphology changed from irregular chain-like aggregates to well dispersed spherical nanoparticles. At the same time, a simple γ-phase was gradually transformed to δ and δ* phases. Dispersion of nano-Al2O3 particles had strong stability. The growth mechanism of particles and aggregates at rapid high-temperature reaction was discussed. The morphology and particle size of prepared nanoparticles depended on the competition among the key influential factors. Related Articles | Metrics Select Study on Synthesis of TiO2 Powder Doped with Sm by Sol-Gel Method and Its Photoluminescent Properties SONG Jin-ling ZHOU Chang-cai HOU Zhi-peng LI Xia CAI Ying ZHANG Yin    2011, 11 (1): 143-147.   Abstract （1822）      PDF （315KB）（474）       Knowledge map    Save The influences of way and quantity of water adding, reaction temperature and inhibitor on the gelatification of sol are studied. The optimal conditions have been finally selected. The adding way of water is dripping, volume ratio of tetrabutyl titanate to water 5:1, reaction temperature 30~35℃ and inhibitor nitric acid. Under the optimized conditions, the TiO2 powder and TiO2 powders doped with different contents of Sm3+ are prepared by the sol-gel method, and their structures and luminescent properties characterized by XRD and photoluminescence spectra, respectively. The results indicate that the structure of prepared TiO2 powder is anatase, and doping ion Sm3+ can restrain the growth of TiO2 crystals. The doped Sm causes the changes of new emission peaks and their intensities under different Sm3+ doping quantities, achieving the minimum value of intensity at 4.0%(w). The morphologies of the TiO2 powder are particles with the diameters of 5~10 nm. Related Articles | Metrics Select Catalytic Activity of Low-loading Pd and Pt Supported Catalysts for Combustion of Dimethyl Ether WANG Yuan-yuan XU Hang FENG Dong-mei WANG Jin-fu    2011, 11 (1): 148-152.   Abstract （1899）      PDF （217KB）（338）       Knowledge map    Save In order to select desirable catalysts for combustion of dimethyl ether (DME), a series of low-loading Pd and Pt catalysts were prepared by impregnation on g-Al2O3. The effects of loading amount and sequence of the metals on catalytic performance were investigated, and the effect of loading molar ratio of the metals. Using 0.025%(w) Pt-loaded catalyst, DME was completely converted to CO2 and H2O at 190℃. The catalyst with Pd and Pt loaded together [Pd:Pt=2:1(mol), Pt 0.025%(w), Pd 0.027%(w), Pt first-loaded] had better performance, by which DME was completely converted at 175℃. Catalytic activity of these two catalysts was decreased by less than 5% after 200 h reaction. Related Articles | Metrics Select Synthesis of Biodiesel Catalyzed by SO3H-functionalized Quaternary Ammonium Ionic Liquids ZUO Shuang LIN Jin-qing SUN Ya-fei FANG Guo-yang    2011, 11 (1): 153-157.   Abstract （1110）      PDF （308KB）（565）       Knowledge map    Save 4 kinds of SO3H-functionalized quaternary ammonium ionic liquid were prepared by two-step method. Their IR and NMR spectra showed that their structures were in accordance with their theoretical structure. Their decomposition temperatures shown by TG were higher than 200℃, so they were enough stable as the catalyst in synthesis of biodiesel. Biodiesel was synthesized with triolein and methanol catalyzed by the 4 kinds of ionic liquid prepared. Their catalytic activity was related to their anion structure, and [n-But3N(CH2)3SO3H][CH3SO3] showed the best catalytic activity. The effects of reaction time, molar ratio of methanol to triolein and catalyst amount on the yield of fatty aid methyl ester were investigated when [n-But3N(CH2)3SO3H][CH3SO3] was selected as the catalyst of transesterification reaction. Under the conditions of molar ratio of methanol to triolein at 12:1, mass fraction of ionic liquid 7%(w), reaction temperature 65℃ and reaction time 24 h, the yield of fatty aid methyl ester reached 89.65%, and the ionic liquid was stable during the reaction and could be reused. Related Articles | Metrics Select Preparation and Characterization of Iron-Nickel Alloy Nanoparticles YUAN Ming-liang TAO Jia-hua YU Liang SONG Cong QIU Guan-zhou    2011, 11 (1): 158-161.   Abstract （1186）      PDF （1696KB）（572）       Knowledge map    Save In ethanol-water system, Fe-Ni alloy nanoparticles were prepared by reduction of the mixture solution of FeSO4 and NiSO4 in the presence of surfactant with liquid-phase reduction method. Their samples were characterized by XRD, SEM and VSM, respectively. The results indicate that single FeNi3 alloy phase could be obtained under the optimized conditions of solution composition of molar ratio of FeSO4/NiSO4 at 1:3, 4 g NaOH and 15 mL N2H4×2H2O at 150℃ for 2 h, the values of saturation magnetization and coercivity were 121.36 A×m2/g, and 1.42 A/m. Besides, the influences of synthesis conditions on the magnetic properties of Fe-Ni alloy nanoparticles were also examined. Related Articles | Metrics Select Research Progress in the Modeling Theory of Airlift Loop Reactor ZHANG Li-ying HUANG Qing-shan    2011, 11 (1): 162-173.   Abstract （1286）      PDF （292KB）（593）       Knowledge map    Save The hydrodynamic models for bubbly flow in airlift loop reactor are reviewed. In addition to the classification of two-fluid models according to the averaging methods, the estimation models of bubble-induced turbulence are also categorized. Furthermore, the inter-phase forces commonly used and some techniques of solving the bubbly flow are summarized and evaluated. It is pointed out that Favre averaging two-fluid model combined with the k-e model, in which the bubble induced turbulence is considered with the Sato model, is a useful tool for the design and scaling-up of airlift loop reactor at the present stage. Moreover, the problems and topics of interest in the future work are suggested on the basis of analysis of state-of-the-art theory of bubbly flow. Related Articles | Metrics Select Recent Research Development in Resolution Kinetics of Racemic Menthol by Lipase NIAN Bao-yi HUANG Zhi-hua LUO Ju-xiang NIU Yu    2011, 11 (1): 174-180.   Abstract （1274）      PDF （331KB）（423）       Knowledge map    Save A condensed review of the potential offered by lipase for resolution of racemic menthols for the past 10 years is presented. Especially, recent applications of the lipase catalytic approach and industrialization of unit operation to the preparation of the most important flavor, l-menthol, are comprehensively covered by analyzing their processes of transesterification, hydrolysis reaction and influential factors. The potential industrial processes based on lipase-catalytic methods are discussed in the terms of their advantages over classical ones. The optimal pathway of resolution is achieved by analyzing resolving routes of menthol and alternative of acyl agent for transesterification of menthol. And a vista of the future investigations is opened up for new realms from macro-kinetics of menthol resolution for the industrial processes. Related Articles | Metrics Select Solid-Liquid Dispersion in a Stirred Tank ZHANG You YIN Xi-xiang HUANG Xiong-bin;    2011, 11 (2): 181-186.   Abstract （974）      PDF （341KB）（302）       Knowledge map    Save The solid-liquid dispersion property by eight types of impeller such as four-pitched-blade turbine (PBT), Rushton turbine (RT), etc, and the influences of stirring power and impeller combinations on dispersion property were studied in a vertical stirred tank with diameter of 0.478 m. Kaolin particles were chosen as the particulate material to be dispersed in the water. The experimental results show that PBT and RT have the optimum dispersion performance, while the 2-blade CBY propeller has the shortest dispersion time. The dispersion rate is in the direct ratio of 1.08 to the stirring power. In the beginning period, the relative dispersion performance Y increases with the stirring power, but the stirring power has little influence on the dispersion performance when the relative dispersion performance Y is more than 0.999. The results also reveal that the combination of a bottom 2-blade CBY and an upper PBT has a clear advantage in continuous operation. Related Articles | Metrics Select Coupled Modeling of Fluid Flow, Heat Transfer and Solidification of Molten Steel in a Casting Mold with Double Horizontally Stabilized Electromagnetic Brakes YUE Qiang ZHOU Li WANG Jian-jun    2011, 11 (2): 187-192.   Abstract （833）      PDF （1430KB）（277）       Knowledge map    Save A three-dimensional model of liquid steel flow, temperature and solidification in a slab casting mold with magnetic induction is presented in FLUENT and magneto-hydrodynamics (MHD). The model is applied to investigate the effects of flow and heat transfer in the mold with and without electromagnetic brakes (EMB), their strength is measured at a steel plant. The results show that free face velocity and penetration depth of liquid steel can be decreased under a constant EMB strength. Electromagnetic forces can be controlled to stabilize the fluid flow in the mold cavity, and shell thickness of slab mold exit position increase 2 mm compared with the mold without EMB. Related Articles | Metrics Select Optimization of Flow Characteristics of Molten Steel in a Five-strand Tundish HAN Jian-jun FAN Xin-you LI Shi-qi WU Long YAN Guo-an GONG Fei DONG Da-xi    2011, 11 (2): 193-198.   Abstract （810）      PDF （217KB）（240）       Knowledge map    Save Flow characteristics in a five-strand tundish No.0 of Shijiazhuang Iron & Steel Co. Ltd. were optimized by hydraulic simulation. Coefficient of variance was used to describe the consistency of molten flow characteristics among strands in the multi-strand tundish. Mean residence time was used as the main evaluating indicator, and peak time, minimum residence time and coefficient of variance were considered as minor evaluating indicators. There were four impact factors considered, turbulence inhibitor, retaining wall, retaining dam and casting speed. The conclusions can be drawn as follows. Compared with that using circular turbulence inhibitor, the mean residence time could be extended by 12 s if quadrate turbulence inhibitor was used. Using V-type retaining wall, the consistency of melt flow characteristic among strands could be better. In addition, the retaining dam should not be used in the tundish, and the casting speed should be kept at 1.5 m/min. Related Articles | Metrics Select Effect of Bed Expansion Height on Electrogenesis Capacity of Anaerobic Fluidized Bed Membraneless Microbial Fuel Cell YUE Xue-hai ZHAO Shu-ju WANG Xu-yun GUO Qing-jie    2011, 11 (2): 199-203.   Abstract （958）      PDF （241KB）（214）       Knowledge map    Save Anaerobic fluidized bed microbial fuel cell (MFC) with 40 mm in diameter and 600 mm in height was employed to investigate the effect of fluidization bed expansion on the electrogenesis capacity of MFC. Three different cathodes were investigated for cathode positions at 150, 250 and 350 mm above distributor. When the expansion height was less than 170 mm, the electrogenesis capacity at cathode 1 was the maximum, up to 347.1 mW/m2. The power density decreased with decreasing cathode position along the bed height. When the expansion height ranged from 170 to 270 mm. The electrogenesis capacity at cathode 2 was larger than that at cathodes 1 and 3, which approached 361.0 mW/m2 when the flow rate of wastewater was kept at 8.35 mm/s. When the expansion height of fluidization bed was 270 to 400 mm, the electrogenesis capacity of three cathodes was all decreased. However, cathode 3 had a minimum decline value, 297.5 mW/m2 at the flow rate of wastewater of 10.61 mm/s. The power density increased with increasing cathode position along the bed height. The results were due to the effects of the flow rate on the mass and electron transport efficiency in anode chamber, and the effects of the flow rate on the growth of microbial film. Related Articles | Metrics Select Experimental Study on Mixing Performance of Improved Intermig Impeller WANG Shu-chan ZHANG Ting-an ZHANG Chao LIU Yan ZHAO Qiu-yue    2011, 11 (2): 204-208.   Abstract （1023）      PDF （238KB）（356）       Knowledge map    Save In order to study mixing performance of a new-style impeller, improved Intermig impeller, in an unbaffled stirred tank of alumina seed precipitator, the profiles of local solid concentration in a liquid-solid system of water-glass bead particles were measured using a PC6D fiber optic reflection probe and analyzed at different conditions. The results showed that the high agitation speed and viscosity of the system are more conducive to uniform distribution. When m=3.50′10-3 Pa·s and n=172 r/min, the multiple relationship of average values of the practice and theory is 1.011 times. It shows that the experimental concentration is closer to theoretical one under this condition, resulting in more even mixing. Related Articles | Metrics Select Dehydration and Electrodeposition of Magnesium from MgCl2×6H2O in Ionic Liquids MA Mei-yan ZUO Yong ZHANG Hai-lang CAI Ying-jun ZHANG Suo-jiang    2011, 11 (2): 209-214.   Abstract （950）      PDF （369KB）（203）       Knowledge map    Save The solubility and dehydration of MgCl2×6H2O in various ionic liquids (ILs) were investigated. The results showed that MgCl2×6H2O and MgCl2 were well soluble (solubility 20%~70%) in hydrophilic ionic liquids, especially those with chloride anion. The moisture content after dehydration was lower than 1′10-4(w) which satisfies the request of electrodeposition. The electrodeposition of magnesium from various MgCl2-ILs systems was further studied. The cathodic limit of ionic liquids (including alkylimidazolium, trialkylimidazolium and quaternary ammonium ILs), the reduction potential of magnesium and deposition process were observed using cyclic voltammetry, SEM and EDS measurements. It is shown that magnesium can be deposited from MgCl2-ILs systems, but the reduction potential of magnesium is not more negative than that for the reduction of ionic liquids cation and reversibility of magnesium is not very well. Related Articles | Metrics Select Effect of Microwave Irradiation on the Penetrability and Dewaterability of Dewatered Municipal Sewage Sludge XIAO Chao-lun TANG Jia-li PAN Feng WANG Juan SUN Yang LIU Hui-zhou    2011, 11 (2): 215-220.   Abstract （851）      PDF （212KB）（234）       Knowledge map    Save The penetrability of microwave at the frequency of 2450 MHz and the power of 500 W was studied in dewatered municipal sewage sludge, and the change of dewaterability of sludge was also studied in the process of microwave irradiation. The results showed that the penetration depth of microwave was 8.7 mm, and the dewaterability of sludge could be improved obviously by proper irradiation. The water content of sludge after centrifugation in the top container was decreased from 80.61% to 75.09% after the sludge was treated for 5 min by microwave irradiation. When the temperature was above about 60℃, microbial cells in sludge began to be broken in large quantities and the intracellular water was released, and the water content of sludge after centrifugation decreased with increasing temperature. When the temperature was above 88℃, the concentrations of extracellular polymeric substances (EPS) had no obvious increase but the hydrophilicity of EPS decreased, and the dewaterability had the quick improvement. Related Articles | Metrics Select Chelating Adsorption Behavior of Imido-acetic Acid-type Composite Chelating Adsorption Material IAA-PEI/SiO2 for Heavy Metal Ions LI Yan-bin GAO Bao-jiao DU Rui-kui;    2011, 11 (2): 221-226.   Abstract （1180）      PDF （230KB）（354）       Knowledge map    Save Polyamine polyethyleneimine (PEI) was grafted onto micron-sized silica gel particles, obtaining the grafted particles PEI/SiO2. Subsequently, the nucleophilic substitution reaction between chloroactic acid and the first and secondary amino groups of PEI/SiO2 was performed, forming the imido-acetic acid (IAA)-type composite chelating adsorption material IAA-PEI/SiO2. The chelating adsorption characteristics of IAA-PEI/SiO2 to heavy metal ions, and the adsorption mechanism were investigated. The experimental results showed that IAA-PEI/SiO2 possesses strong adsorption ability for heavy metal ions by right of the synergism of electrostatic interaction and coordination chelating action between imido-acetic acid groups and heavy metal ions. The adsorption process of IAA-PEI/SiO2 towards heavy metal ions is exothermic. In the pH range, the hydrolysis of the heavy metal ions can be inhibited, the chelating adsorption ability of IAA-PEI/SiO2 to heavy metal ions increases with increasing pH value. The adsorption ability order of IAA-PEI/SiO2 to heavy metal ions is Ni2+>Pb2+>Cu2+>Cd2+. Related Articles | Metrics Select Adsorption Behavior of Iron Oxide Coated Pumice for Phosphate PAN Yong-zhang ZHU Feng    2011, 11 (2): 227-232.   Abstract （944）      PDF （441KB）（199）       Knowledge map    Save Natural pumice was modified with iron oxide and tested as an adsorbent for the removal of phosphate from water, and the thermodynamics and kinetics of phosphate adsorption from aqueous solution using iron oxide coated pumice (IOCP) were investigated. The results indicated that the Langmuir model fit the equilibrium data better than the Freundlich model. The maximum adsorption capacity of 0.63~1.20 mm IOCP for phosphate was found to be 0.245 mg/g at 298 K. Evaluation of the experimental data in terms of adsorption kinetics revealed that the adsorption of phosphate onto IOCP followed well the pseudo-second-order kinetic model. The calculated values of DG0, DH0 and DS0 at different temperatures indicate that the adsorption is a spontaneous and endothermic process. The results of SEM and EDAX analysis showed that phosphate ions were chemisorbed on the surface of IOCP. Related Articles | Metrics page Page 1 of 5 Total 178 records First page Prev page Next page Last page