Volumn Content

The Chinese Journal of Process Engineering 2010 Vol.10 Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Investigation on Turbulent Flow Characteristics in a Solid-Liquid Square Stirred Tank Using 2D-PIV Method JIANG Han LIU Xin-hong HUANG Xiong-bin;    2010, 10 (1): 1-9.   Abstract （1412）      PDF （912KB）（667）       Knowledge map    Save Two-dimensional particle image velocimetry and digital image analysis were used to quantify the hydrodynamics of solid-liquid suspension in a square stirred tank. Solid particle spheres with 750 mm diameter were employed as the dispersed phase with up to volumetric concentration of 0.9%(j) in water. The magnitude of continuous phase mean axial velocity decreased in the impeller and near-wall regions, as the solid concentration increased, the relationship of the velocity drop and the particle concentration could be respectively described as Dv*μCv0.776 and Dv*μCv1.474. The turbulent kinetic energy distribution of the continuous phase was complex, because it increased in the impeller region with the solid volumetric concentration up to 0.5%(j) and decreased above that. The average turbulent kinetic energy remained decreased as the particle concentration increasing from 0.2% to 0.9%(j), the relationship could be described as ( μCv-0.073). By contrast, the average turbulent kinetic energy dissipation rate of the continuous phase was more enhanced than that in the single phase flow, which could be described as μCv1.113. Related Articles | Metrics Select Model of Dynamic Distribution of Dissolved Oxygen Concentration and Oxygen Concentration Changing Rate of Hepatocyte in a Cylindrical Reactor of Bioartificial Liver LIU Jian-feng SONG Tao WANG Zhe JIANG Wei    2010, 10 (1): 10-16.   Abstract （1234）      PDF （233KB）（500）       Knowledge map    Save A mathematic mechanism model of dynamic distribution of dissolved oxygen concentration in a cylindrical bio-reactor was built up based on the modeling method of artificial liver bioreactor. Oxygen concentration changing rate of hepatocyte was analyzed on the basis of the model, a real-time detection method advanced, and the relationship between the real-time oxygen concentration changing rate and the total oxygen concentration changing derived. Finally, the comparison between simulation data and measured data verified the correctness of model, and the average error was within 5%, and the error of oxygen concentration changing rate within 1%. In the meantime, the experimental results verified the relationship between the total oxygen concentration changing and real-time oxygen concentration changing rate, a correlation was obtained as dDO=MNDhR/V. Related Articles | Metrics Select Attrition of Activated Carbon Particles in a Coupled Fluidized and Fixed Bed Reactor YUN Song QIAN Wei-zhong WEI Fei    2010, 10 (1): 17-22.   Abstract （1410）      PDF （213KB）（655）       Knowledge map    Save The cold model experiments on the attrition of activated carbon particles were conducted in a steel-made coupled fluidized and fixed bed reactor with a diameter of 50 mm at 130~150℃. The relationship between the weight loss of particles (4.2 mm in diameter, cylinder-like particles) at the fixed bed section and gas velocity was analyzed. The fine particles (0.2 mm in average size, pristine) of fluidized bed reactor, remained in the fluidized bed, fixed bed and the filter after fluidization, were studied thoroughly to understand their profiles of particle size and their mass ratio in different positions under different gas velocities. It was found that the attrition of particles was serious. Under the high gas velocity (0.212~0.424 m/s), the weight loss of particles in the fixed bed was 3%~4%, and the mean size of fine particles in the fluidized bed was reduced from 200 mm to below 100 mm. Related Articles | Metrics Select Experimental Study on the Performance of a Pulsed Fluidic Sampler LIU Bin-bin XU Cong    2010, 10 (1): 23-28.   Abstract （1289）      PDF （259KB）（484）       Knowledge map    Save A pulsed fluidic sampler without moving mechanical components with little maintenance was studied using glycerol-water system as working liquid. The effects of viscosity, static pressure, T-section cross-sectional area and down comer length on sampling performance of the sampler were investigated. The results indicated that the sampling quantity was reduced with increase of system viscosity from 14.6 to 6.1 mL, increased with increase of T-section cross-sectional area and more significant increasing trend with increase of system viscosity, and significantly reduced from 19 to 3.8 mL when the down comer length was reduced from 2.65 to 0.684 m. The effect of static pressure on the sampling quantity was very small. The source of sampling driving force was significant reduction of pressure in sampling needle tip, which was caused by the discontinuous flow fluid in the down comer. Related Articles | Metrics Select Effective Thermal Conductivity of Fixed Packing Bed of Cobalt-based Catalyst WU Jian-min ZHANG Hai-tao YING Wei-yong FANG Ding-ye    2010, 10 (1): 29-34.   Abstract （2368）      PDF （332KB）（560）       Knowledge map    Save The effective thermal conductivity coefficient of stagnant fixed bed packed with cobalt-based catalyst is measured using the steady state method in the temperature range of 165~265℃ at normal pressure. The correlation of the stagnant effective thermal conductivity coefficient with the thermal conductivity of fluid and catalyst is obtained based on the steady-state theory. The maximum deviation and standard deviation of the experimental results from the correlated equation are 1.74% and 0.43%, respectively. And the stagnant effective thermal conductivity coefficients from experiments are also compared with the predicted values. They are in good agreement. Related Articles | Metrics Select Numerical Simulation of Inclusion Removal with Argon Blowing in a Slab Continuous Casting Mold LUO Zhi-guo; NI Bing; DI Zhan-xia; LIU Hong-hua    2010, 10 (1): 35-40.   Abstract （1349）      PDF （787KB）（474）       Knowledge map    Save Aiming at the removal of non-metallic inclusions in liquid steel in a slab continuous casting mold, the harmonious phase model (HPM) and discrete phase model (DPM) were used to describe the particle behavior and removal rate in water-air-inclusion simulation and steel-argon-inclusion systems. The results showed that the argon blowing promotes inclusion removal. In the study on the mold, inclusion removal efficiency is the lowest at 1.3 m/min casting speed with 6.0 L/min gas flow rate. The inclusion trapping rate from domain decreases with the increase of gas flow rate blown, the critical 9.0 L/min gas flow rate is obtained at 1.2 m/min casting speed, while the inclusion trapping rate into slab increases with the increase of gas flow rate beyond the critical one. HPM and DPM can simulate behavior and removal of inclusions in the gas-liquid two-phase flow. Related Articles | Metrics Select Separation Performance of Multi-cyclone Separator for Purification of Natural Gas WU Xiao-lin XIONG Zhi-yi JI Zhong-li    2010, 10 (1): 41-45.   Abstract （1558）      PDF （236KB）（533）       Knowledge map    Save In order to evaluate the separation performance of multi-cyclone separator for purification of natural gas, the overall collection and grading efficiencies of a multi-cyclone separator with inlet velocities of 6~24 m/s and particle concentrations of 30~2000 mg/m3 were investigated under atmospheric pressure and room temperature. The particle concentration and particle size distributions of inlet and outlet of the cyclone separator were measured by aerosol spectrometer based on measured particle number. The experimental results showed that the overall collection efficiency and grade efficiency increased with increasing of particle concentrations and inlet velocities. The overall collection efficiency of multi-cyclone separator was 2%~15% less than that of single cyclone separator at the same operation condition. Most of the particles with the diameters bigger than 15 mm could be removed by multi-cyclone separator while single cyclone separator could remove clearly the particles bigger than 10 mm. The pressure drop of the single cyclone separators in a multi-cyclone occupied 80%~90% of the overall pressure drop of multi-cyclone separator. Related Articles | Metrics Select Fluidization Characteristics of Mixture of Straw and Semi-char Particles in a Fluidized Bed ZHU Jin-zhong CHEN Xue-li WANG Fu-chen    2010, 10 (1): 46-50.   Abstract （1372）      PDF （216KB）（470）       Knowledge map    Save Fluidization characteristics of straw and semi-char particles were investigated in a fluidized bed with I.D. of 100 mm and height of 1000 mm. The results show that straw particles can not be fluidized alone, but the semi-char particle fluidized well. The minimum fluidization velocities of semi-char particles increase with the particle size, but they are independent of the bed height, the minimum fluidization velocities of semi-char particles (with the sizes of 0.45~0.90, 0.18~0.45, 0.125~0.18 mm) are 0.19, 0.16, 0.14 m/s. The fluidization characteristics of semi-char particles at different temperatures (300~550℃) are similar. The fluidization characteristics of the mixture are well as long as the mass fraction of straw is less than 20%, but the minimum fluidization velocities of the mixture increase with the mass fraction of straw in the mixture. Related Articles | Metrics Select Mixing and Segregation of Particles in a Gas-Liquid-Solid Fluidized Bed in Batch Operation ZHOU Li ZHONG Hong LI Chao    2010, 10 (1): 51-55.   Abstract （2229）      PDF （380KB）（454）       Knowledge map    Save Experiments were carried out to examine axial concentration distribution and mixing and segregation behaviour of binary solids mixtures in a three-phase fluidized bed of 41 mm I.D. and 1500 mm height under batch operation mode. Macroporous adsorption resin and rubber balls with different diameters but similar density were employed in the experiments. Multiple shutter plates and bed expansion method were used to determine axial variation of the bed properties including concentrations of particles in the binary mixture and gas hold-ups. The sedimentation-dispersion model which was employed to describe two-phase fluidized bed could be modified to describe three-phase fluidized bed. Experimental results show that the sedimentation-dispersion model could be used to describe the gas-liquid-solid three-phase fluidized bed of solid concentration distribution, and Fan's assumption was established. Related Articles | Metrics Select Experimental Study on Gas Flow Field in a Rotating Zigzag Bed WANG Hong-jun LI Yu-min WANG Hong-jun    2010, 10 (1): 56-59.   Abstract （2243）      PDF （216KB）（549）       Knowledge map    Save The experiment was carried out in a rotating zigzag bed (RZB) with a rotor in 488 mm diameter and 104 mm height for measurement of gas flow field in inner chamber of the rotor by using five-hole probe at various rotational speeds and gas flowrates. By analysis and calculation, vector diagram of the gas flow field was given. The experimental results showed that gas in the rotor of RZB spiraled upward and downward. The tangential velocity was far greater than radial and axial velocities. According to angular momentum conservation law, the smaller the distance to the axis of RZB, the larger the tangential velocity. In addition, the effects of rotational speed and gas flowrate on the gas flow field were analyzed, and the distributions of static pressure and total pressure in the rotor of RZB obtained. Using experimental data, when the radius was reduced by 16.97%, the rotational speed of rotor increased by 54.18% and gas flowrate increased by 3.11 times, the tangential velocity increased by 12%~41%, 58%~88% and 29%~73%, respectively. Using dimensionless Reynolds number, radius and centrifugal acceleration, an empirical formula for calculating the tangential velocity was obtained, and the calculation results agreed well with the experimental ones. Related Articles | Metrics Select Leaching Kinetics of Vanadium Pentoxide from Ash of Stone Coal by Sulfuric Acid XU Yao-bing LUO Zhong-yang WANG Qin-hui ZHOU Jin-song SHI Zheng-lun    2010, 10 (1): 60-64.   Abstract （1397）      PDF （231KB）（581）       Knowledge map    Save The leaching kinetics of vanadium pentoxide from ash of stone coal by sulfuric acid was approached using the shrinking unreacted core model for the reaction between liquid and solid. The influences of temperature and sulfuric acid concentration on the reaction rate of vanadium pentoxide were investigated. The results show that the diffusion through the solid film was the rate limiting step in the leaching process of vanadium pentoxide within the selected temperature range from 30 to 115℃, and the apparent activation energy was calculated to be 29.96 kJ/mol. In the selected sulfuric acid concentration range from 3.0 to 6.0 mol/L, the rate limiting step changed from chemical reaction to diffusion through solid film when sulfuric acid concentration was over 6 mol/L. The apparent reaction progression was 1.199. The leaching rate was increased by enhancing the temperature. When sulfuric acid concentration was less then 6 mol/L, the leaching rate was remarkably increased by enhancing the sulfuric acid concentration. But the leaching rate was little affected as the sulfuric acid concentration was over 6 mol/L. Related Articles | Metrics Select Preparation of Activated Carbon from Shell of Carya cathayensis S. and Its Adsorption Behavior of Aniline YU Xiao-jie ZHOU Cun-shan WANG Yun-xiang PANG Lin-jiang    2010, 10 (1): 65-69.   Abstract （1422）      PDF （215KB）（714）       Knowledge map    Save The conditions for preparation of activated carbon from walnut (Carya cathayensis S.) shell were studied with phosphate method, and optimized with orthogonal experiments taking phosphate concentration, carbonizing temperature and time as influential factors, methylene blue adsorption, iodine value and yield as indexes, and the adsorption process was analyzed in thermodynamics. The results showed that the adsorption value of the activated carbon to methylene blue was 102 mL/g, the iodine value 804.36 mg/g, and the yield 53.21%, which was produced at the conditions of 300℃ activation temperature, 45 min activation time and phosphate concentration 50%(w). In the studied conditions, the adsorption increased with increasing of temperature, acidic condition was beneficial to the adsorption. The equilibrium data fit well with Freundlich isotherm, and the thermodynamic parameters indicated that the adsorption reaction was exothermic and spontaneous. Related Articles | Metrics Select Synthesis of p-Methoxyacetophenone Catalysed with Hb Zeolite and Competitive Adsorption of the Reactants and Products CHEN Ping ZHAI Yu-chun    2010, 10 (1): 70-74.   Abstract （1438）      PDF （270KB）（503）       Knowledge map    Save The heterogenous Friedel-Crafts acylation of anisole with acetic anhydride using Hb zeolite as catalyst was carried out without any solvent. p-Methoxy acetophenone selectively and rapidly formed on the fresh zeolite catalyst. The effects of molar ratio of reactants, dosage of catalyst and reaction temperature on the yield of products were investigated. Under the feasible reaction conditions of anisole (AN) of 0.1 mol, anisole/acetic anhydride (AN/AA) molar ratio of 1:1.5, catalyst dosage of 1.0 g, reaction temperature of 95℃ and reaction time of 4 h, the highest yield of p-methoxy acetophenone was achieved up to 73.25%. The reaction kinetics was studied by Langmuir-Hinshelwood model. The adsorption equilibrium constants (AEC) for reactants and products as well as the rate constants for the acylation reaction were obtained respectively based on hypotheses of quasi-initial and quasi-stationary states. The result showed that the competitive adsorption effects of reactants and products resulted from differences in their adsorption equilibrium constants. The estimated values of AEC indicated that the acylation product p-methoxyacetophenone was adsorbed strongly more than the reactants. The AEC values of p-methoxyacetophenone decreased with the increase in reaction temperature. Related Articles | Metrics Select Adsorption of Phosphate in Waste Water with Steel Slag HUA Quan-xian TANG Jian-wei LIU Yong; ZHANG Bao-lin WEI Hui; HUANG Ying;    2010, 10 (1): 75-79.   Abstract （1460）      PDF （209KB）（451）       Knowledge map    Save The oscillation experiments were carried out to study the characteristics behavior of phosphate adsorption on steel slag. The results showed that isothermal adsorption data fitted to both Langmuir and Freundlich equations and the adsorption was preferential type. The theoretical saturated capacity was 0.33 g/kg. Phosphate adsorption kinetics fitted to pseudo-second order Lagergren equation. Equilibrium adsorption amount increased with raising reaction temperature. The adsorption rate was governed by both liquid film diffusion and intra-particle diffusion. Thermodynamics parameters of phosphate adsorption were DH>0, DG<0, and DS>0, which indicated that the adsorption behavior was endothermic, spontaneous and physical process, and temperature elevation promoted adsorption. Related Articles | Metrics Select Vacuum Distillation of Pb-Pd Alloy YANG Chun-yu; QIU Ke-qiang; LIN De-qiang    2010, 10 (1): 80-83.   Abstract （1468）      PDF （245KB）（462）       Knowledge map    Save The basic rule of vacuum distillation of Pb-Pd alloy was investigated. The primary distillation results show that the removal rate of Pb was close to 92.5% and the Pd content in the primary distillation residue remained at about 60% when the Pb-Pd alloy containing 10%(w) Pd was distillated for more than 4 h at 1250 K and 35 Pa. After the secondary distillation at 1523 K, the Pd content in the secondary residue was still maintained at about 60%. In the vacuum distillation process of Pb-Pd alloy, most of Pb could be separated and collected as metallic Pb, while Pd was enriched in the residue. As a result, the material amount of further treatment for extraction of Pd was reduced remarkably by this method. Related Articles | Metrics Select Recovery of Zinc Concentrate and Preparation of Iron Red from High Iron and Low Zinc Wastewater from Extraction of Indium ZENG Mao-hua LI Zai-bo ZHAO Xu-guang XI Chang-sheng YE Fang;    2010, 10 (1): 84-90.   Abstract （1292）      PDF （303KB）（483）       Knowledge map    Save Recovery of zinc concentrate and preparation of iron red from high iron and low zinc wastewater from extraction of indium were carried out by controlling pH value of the solution. The recovery effect of zinc using different sulfides was studied. Technological conditions for preparing zinc concentrate and high-purity iron red using ultrasonic were investigated, and the morphology and granularity of zinc concentrate also characterized through SEM analysis. For the wastewater containing 60.47 g/L iron and 28.65 g/L zinc, the optimum process conditions were defined as pH value 2, pyrite concentrate -0.074 mm, and ultrasonic treatment time 50 min. The result showed that the product of zinc concentrate was obtained with 50.36% zinc, and its recovery rate reached 95.29%, which was much higher than 18.52% and 23.67% respectively under normal treatment. The recovery rate of iron reached 92% with high-purity iron red which can be qualified as the first grade product according to state standard of SJ/T10383-93. Related Articles | Metrics Select Phase Controlling of Hydrated TiO2 Formed under Low Titanium Concentration in Sulfuric Acid Solution SONG Hao LIANG Bin LV Li WU Pan LI Chun    2010, 10 (1): 91-96.   Abstract （1476）      PDF （386KB）（488）       Knowledge map    Save The relationship between hydrolysis condition and phase of hydrated TiO2 formed at low titanium concentration in sulfuric acid solution was investigated. The results showed that the polymorphic phase of titanium hydrolysate could be controlled by adjusting the feeding rate of titanium sulfate stock solution and concentration of sulfuric acid. When the feeding rate of stock solution was below 2 mL/h in 2.5%(w) sulfuric acid solution at 100℃, the hydrated titania was rutile, however, with that increasing to 8 mL/h, or the sulfuric acid concentration increasing to above 10%(w), the predominant phase switched to be anatase. The phase strongly depended on the rate and stage of hydrolysis. A rapid hydrolysis during homogeneous nucleation period generally led to the formation of an anatase hydrolysate. And in the nuclei growth stage slow hydrolysis process was beneficial to the formation of rutile, which was thermodynamically stable phase in acidic solution. Related Articles | Metrics Select Catalytic Conversion of Ethanol to Light Olefins over Fe2O3/HZSM-5 Catalyst ZHU Jian-hong YU Jian DUAN Zheng-lian; ZHANG Zhan-guo XU Guang-wen;    2010, 10 (1): 97-102.   Abstract （1478）      PDF （309KB）（510）       Knowledge map    Save The catalytic conversion of ethanol to light olefins over Fe2O3/HZSM-5 catalyst prepared with impregnation method was investigated. The selectivity of olefins was tested against the ratio of silica to alumina and amount of iron oxide in catalyst, reaction temperature and pretreatment method for the catalyst in the temperature range of 400~500℃. It was demonstrated that propylene and butylenes were in good yield at the ratio of silica to alumina of 140, while iron impregnation onto HZSM-5 obviously increased the yields of these light olefins. The highest propylene yield of about 25% was realized when iron oxide loading was 2.9%. Elevating reaction temperature increased the selectivity to propylene at the initial reaction stage but shortened the activity lifetime of catalyst. Catalyst reduction in advance with H2 further promoted the production of propylene and ethylene. Related Articles | Metrics Select Treatment of Nickel-containing Wastewater by Sulfate Reducing Bacteria with Rice Chaff as Immobilized Carrier LI Juan LI Hao-ran SUN Chun-bao    2010, 10 (1): 103-108.   Abstract （1331）      PDF （509KB）（537）       Knowledge map    Save A sulfate reducing bacterium was screened from the activated sludge. Complete rice chaff, gravel with 3~6 mm diameter and alginate-calcium chloride spheres with 4 mm diameter were used to make immobilized carrier. Comparative study on treatment of nickel-containing wastewater was carried out using an immobilized column filled with immobilized bacteria. The experimental results show that the immobilized column using rice chaff as carrier had a short start-up time and a better effect on removal of nickel ions in the wastewater. The nickel removal rate of immobilized column with rice chaff as carrier operated for 3 d could reach 95% and kept stable when the initial concentration of Ni2+ was 100 mg/L and the liquid volume 5 mL/d under the conditions of 31℃ and pH=7. Then the concentration was changed to 200 and 300 mg/L after 25 and 50 d with other conditions kept invariant, the removal rate remained up to 95%. The immobilized column was penetrated until the concentration and volume of the liquid feed were increased to 400 mg/L and 20 mL/d, and the nickel removal rate was lower than 40%. Related Articles | Metrics Select Simulation of Fabrication Process of Hollow Glass Microspheres by Sol-Gel Technology QI Xiao-bo; ZHANG Zhan-wen; LI Bo; CHEN Su-fen; SHI Tao;    2010, 10 (1): 109-114.   Abstract （1474）      PDF （269KB）（555）       Knowledge map    Save Based on the analysis of heat, mass and momentum transfer in the transformation process from dried gel particles to hollow glass microspheres, a mathematic model was established to simulate the temperature, mass, velocity and diameter of particle/microsphere in the transformation process. The temperature difference and heat transfer coefficient between furnace and particle/microsphere was also investigated. The results show that in the heating and encapsulating stages, the surface of dried gel particles have extremely high heating-up rate (1000~2000℃/s), and consequently the encapsulation process can be completed in very short time (<1 s) and distance (<4.5 cm). The cooling rate of liquid glass microspheres can not be improved by increasing the heat transfer rate of furnace atmosphere, since the cooling rate of liquid glass microspheres depends on the axial temperature gradient of cooling zone of drop-tower furnace. The simulation results agree well with the experimental results. Related Articles | Metrics Select Enhanced Formation of HCFC141b Hydrate with HCFC141b-in-water Emulsion ZHOU Xi-tang GUAN Jin-an LIANG De-qing    2010, 10 (1): 115-120.   Abstract （1417）      PDF （157KB）（393）       Knowledge map    Save Enhanced formation of HCFC141b hydrate was studied with HCFC141b emulsion before the hydrate formation. Tergitol TMN6 was selected as emulgator, HCFC141b and water were introduced into an airtight emulsifier at the molecular ratio of 17:1 and emulsified at the temperature of 14℃ under the stirring speed of 4000~6400 r/min. And HCFC141b hydrate formed and decomposed with the change of programmed temperature. The experimental results showed that with the new method HCFC141b hydrate began to form in the time of 30 min (in glycol-water bath) or 100 min (in air bath) even in static state, and under the same condition with conventional method (non-emulsion) the hydrate could not form, at least it difficultly formed. And in dynamic state HCFC141b emulsion formed hydrate in 20 min earlier than the mixed liquid did, liquid from hydrate decomposition was emulsified after brief stirring, and formed hydrate again more easily than the brand-new emulsion. Related Articles | Metrics Select Experimental Study on Controlling Step of Self Reduction Process of Carbon Composite Iron Ore Hot Briquette CHU Man-sheng WANG Zhao-cai LIU Zheng-gen LU Ji-ping    2010, 10 (1): 121-126.   Abstract （2249）      PDF （303KB）（487）       Knowledge map    Save Corresponding to the ascertained conditions of heat transfer and temperature range of 900~1150℃, self-reduction experiments of carbon composite iron ore hot briquette (CCB) are studied. By analyzing the changes of reduction weightloss and product gases of CCB, self reduction mechanism of CCB is explained. The experimental results show that the self-reduction of CCB in N2 atmosphere meets homogeneous and porous material model. The whole reduction process could be divided into two stages, the reduction rate during the first stage is significantly faster than that during the second one. In the experimental conditions, the reduction of CCB is controlled by the step of gas inner diffusion through the layer of reduction iron product. Related Articles | Metrics Select Vacuum Thermal Reduction Kinetics of Calcined Dolomite with Al-Si-Fe Alloy HU Wen-xin; LIU Jian; FENG Nai-xiang PENG Jian-ping    2010, 10 (1): 127-132.   Abstract （1412）      PDF （322KB）（521）       Knowledge map    Save Vacuum thermal reduction kinetics of calcined dolomite with Al-Si-Fe alloy was studied using shrinking unreacted-core model. The effects of pellet forming pressure, reduction temperature (T), and villaumite on reduction rate (R) of calcined dolomite were investigated. The results show that within the pellet forming pressure from 40 to 150 MPa, the reduction rate is increased with increasing of the pressure. Villaumite can accelerate the reduction rate and then increase the reduction rate, and the optimal conditions are reduction temperature 1413 K, reduction time (t) 120 min, vacuity 4 Pa, pellet forming pressure 150 MPa and addition of CaF2 3%. The reduction process is the first order reaction and controlled by diffusion of reductant in solid product layer. The equation for the reduction kinetics is 1+2(1-R)-3(1-R)2/3=0.194exp(-8.38×103/T)t, and the apparent activation energy 69.7 kJ/mol. Related Articles | Metrics Select Vacuum Carbothermal Reduction Kinetics of Zinc Oxide Ore XIONG Li-zhi CHEN Qi-yuan YIN Zhou-lan ZHANG Ping-min    2010, 10 (1): 133-137.   Abstract （1612）      PDF （205KB）（630）       Knowledge map    Save The kinetics of vacuum carbothermal reduction of zinc oxide ore was investigated. Experimental results indicated that the reduction ratio of zinc was increased by increasing the molar ratio of C/Zntotal or the reaction temperature. Furthermore, it decreased with increase in either the size of zinc oxide ore or pressure of system. The results revealed that carbon gasification or interface reaction had a lesser effect, but the gas diffusion of Zn vapor and CO had a very important effect on the reduction reaction at 1073~1223 K. The gas diffusion was the rate-determining step of overall reduction process, in which activation energy was estimated to be 177.72~191.31 kJ/mol. Related Articles | Metrics Select Release of Nitrogen and Phosphorus from Sewage Sludge Pretreated by Microwave Irradiation CHENG Zhen-min WEI Yuan-song LIU Jun-xin    2010, 10 (1): 138-141.   Abstract （1416）      PDF （192KB）（513）       Knowledge map    Save Release of nitrogen and phosphorus from sewage sludge produced by a municipal waste water treatment plant was investigated in a microwave reactor under atmospheric pressure and T≤100℃. Phosphorus and nitrogen in the sludge were rapidly released into the supernatant in the microwave irradiation process without any chemical agent addition. Under the same input of microwave energy, the concentrations of phosphorus and nitrogen in the supernatant after microwave irradiation were increased along with the increase of sludge concentration. The higher the microwave power, the faster the release of phosphorus and nitrogen. The concentrations of total phosphorus and total nitrogen in the supernatant increased from 2.05 and 19.58 mg/L before treatment respectively to 31.46 and 115.10 mg/L with only 100 s of 900 W microwave irradiation. Related Articles | Metrics Select Catalytic Oxidation of NO over CuSO4-CeO2/TiO2-SiO2 Catalyst and Its Property against the Effcts of H2O and SO2 XIA Bin TONG Hua; HUANG Yan; LUO Jing; LUO He    2010, 10 (1): 142-148.   Abstract （1390）      PDF （406KB）（569）       Knowledge map    Save CuSO4-CeO2/TS catalyst impregnated on TiO2-SiO2 (TS) support was prepared by coprecipitation method. The effects of loading, calcination temperature, volume fractions of NO and O2, and space velocity on CuSO4-CeO2/TS catalytic oxidation of nitric oxide were studied, and the resistance to poisoning of H2O and SO2 was also investigated. The support and catalysts were characterized by BET, XRD and FT-IR analysis. The results showed that the optimum catalyst could obtain the oxidation rate (NO2/NOx) about 67.5%, when the volumetric fraction of NO was 500′10-6, O2 8% and space velocity 10000 h-1 at 350℃ of reaction temperature, which could meet the condition of the highest absorption efficiency of NOx. But because of the higher reaction temperature and O2 content in the NO catalytic oxidation, the resistance to poisoning of H2O and SO2 was worse than that used in selective catalytic reduction process. Related Articles | Metrics Select Morphology Self-assembly of Ordered Mesoporous MgAlPO Synthesized by Ultrasound-assisted Solid State Chemical Reaction at Low Temperature LIU Shao-you JIANG Tian-zhi TANG Wen-hua    2010, 10 (1): 149-154.   Abstract （1457）      PDF （434KB）（498）       Knowledge map    Save With the ultrasonic-assisted approach, ordered mesoporous magnesium aluminophosphate (MgAlPO) crystalline powder was prepared by a solid-state reaction of maganesium chloride hexahydrate (MgCl2×6H2O), aluminium chloride hexahydrate (AlCl3×6H2O) and disodium hydrogen phosphate dodehydrate (Na2HPO4×12H2O) with cetyltrimethylammonium bromide as a template. Its properties were characterized by SEM, XRD, HRTEM, N2-physisorption at 77 K, FT-IR and EDS. The self-assembly mechanism of MgAlPO ordered mesoporous material was also investigated. The results show that magnesium was doped into the framework of aluminophosphate by isomorphous substitution of metal magnesium and then the ordered mesoporous material MgAlPO formed. The mesoporous channels in the material were arrayed by paralleogram. Its morphology was spherical from the self-assembly of nanoparticles with various sizes. Meanwhile, the specific surface area of 502.7 m2/g, pore radius size distribution centre of 1.21 nm and pore volume of 0.3378 cm3/g in the obtained material were measured. Related Articles | Metrics Select Preparation and Characterization of Gold Nanoparticles by Hydrothermal Technique in a Phosphotungstate Acid Solution System ZHANG Li; WANG Cong; ZHUO Xin; TAO Shu-hua;    2010, 10 (1): 155-160.   Abstract （1481）      PDF （632KB）（443）       Knowledge map    Save Gold nanoparticles were synthesized by reduction of chloroaurate acid (HAuCl4) through hydrothermal synthesis. The effects of influential parameters on synthesis of gold nanoparticles were studied, such as molar ratio of HAuCl4 to phosphotungstate acid, reaction time, and reaction temperature. Morphology, composition, particle size and structure of the gold nanoparticles were characterized by TEM, UV-Vis, FESEM, XPS, and XRD. The results showed that the reaction rate of HAuCl4 and phosphotungstate acid was fast. Au particles with different sizes were synthesized. The morphologies of Au particles such as sphere-like, triangular, multiple-twinned particles, and hexagonal ones could be obtained. The formation mechanism of Au particles was also discussed. Related Articles | Metrics Select Hydrothermal Stability of Microporous SiO2 Membranes QI Hong; HAN Jing; JIANG Xiao-luo; TAO Zhen; XING Wei-hong FAN Yi-qun    2010, 10 (1): 161-166.   Abstract （1470）      PDF （296KB）（598）       Knowledge map    Save Preparation and hydrothermal stability of microporous silica membrane were studied. A stable SiO2 polymeric sol was successfully synthesized with tetraethylorthosilicate as precursor through polymeric sol-gel route. a-Al2O3 supported defect-free mesoporous g-Al2O3 disk membrane with average pore size of about 3 nm was fabricated via dip coating and subsequently calcined at 600℃. The effect of calcination temperature on the properties of SiO2 powder and gas permeabilities of supported SiO2 membranes, especially with regard to the hydrothermal stability of SiO2 microporous membranes, was studied in detail. The results show that He permeability of SiO2 membranes calcined at 400~800℃ was (7.29~12.7)′10-8 mol/(m2×s×Pa) at 200℃ and 0.3 MPa. The permselectivity of He with respect to CO2, O2, N2, CH4 and SF6 was 98, 49, 64, 79 and 91, respectively, indicating a molecular sieving effect. The calcination temperature played a key role in determination of the hydrothermal stability of microporous silica membrane, which was confirmed experimentally. The performance of SiO2 membrane calcined at 400, 600 and 800℃ deteriorated under the H2O pressures of 8, 200 and 200 kPa, respectively. Related Articles | Metrics Select Preparation and Characterization of High Temperature Protective Ceramic Coating for Plain Carbon Steel ZHOU Xun Lianqi Wei LIU Peng WANG Xiao-jing YE Shu-feng CHEN Yun-fa    2010, 10 (1): 167-172.   Abstract （2169）      PDF （346KB）（563）       Knowledge map    Save A new high temperature protective ceramic coating used on the surface of plain steel was prepared by mechanical mixing method. The coating was consisted of magnesia, titania, alumina and calcium oxide mixture. Such a coating, when it was applied superficially on Q235B plain steel surface, could form a compact scale and enhance oxidation resistance at 1300℃. The experimental result showed that the granularity between 48~75 mm and coating layer thickness of 0.5 mm were needed to observe the coating performance. The coating could work effectively in the temperature range of 900~1300℃. Metal loss was diminished by 59.36% compared with the uncoated sample at 1300℃. Duration of the coating could last over 8 h. The ceramic coating converted the scale structure from classic Fe2O3/Fe3O4/FeO three layers to one spinel layer, suppressed the growth of iron oxides and decreased Fe diffusion speed sharply at elevated temperature. Related Articles | Metrics Select Synthesis and Characterization of High Degree of Substitution Cassava Carboxymethyl Starch TAN Yi-qiu HUANG Zu-qiang NING ke-liang    2010, 10 (1): 173-178.   Abstract （2235）      PDF （691KB）（564）       Knowledge map    Save Carboxymethyl starch (CMS) with high degree of substitution (DS) was synthesized by ethanol method, using cassava starch activated for 60 min as material. The process conditions were optimized by orthogonal experiments, the effects of reaction time, reaction temperature, catalyst amount, etherifying agent amount, concentration of ethanol and concentration of starch on DS of CMS were investigated. The results indicated that the optimized conditions for synthesis of high DS cassava CMS were temperature 50℃, concentration of ethanol 90%, reaction time 120 min, molar ratio of ClCH2COOH to starch 0.80, concentration of starch 35%(w) and molar ratio of NaOH to starch 0.80. The value of DS was 1.24 under the synthetic conditions. Furthermore the product was further characterized. Related Articles | Metrics Select Effect of Activation Temperature on Synthesis of LiMnPO4 Nano-crystallites via Solid State Reaction HUANG Ying-heng TONG Zhang-fa LAN Jian-jingC HEN Yi-zu    2010, 10 (1): 179-184.   Abstract （1413）      PDF （502KB）（574）       Knowledge map    Save The nano-crystallites of LiMnPO4 powder were successfully prepared after calcining the precursor of NH4MnPO4 at high activation temperature. The precursor was prepared with lithium hydroxide, monoammonium phosphate and manganese acetate via solid state reaction at low temperature. The effect of activation temperature on the crystallization process of LiMnPO4 was characterized by infrared spectroscopy, XRD, TG-DTA and SEM. The results showed that the synthesis of LiMnPO4 was involved in variety of kinetic competition at high activation temperature, but the calcination process was the control step of synthesis, the kinetic index number of crystal growth 1.1, and the activation energy of nano-grain growth 20.95 kJ/mol. And the particle size of LiMnPO4 was controlled in the synthesis process at different activation temperatures, and LiMnPO4 was used as hydrogen precipitation electrode material, the electrode equilibrium potential was changed by LiMnPO4 particle size. Related Articles | Metrics Select Hydrothermal Synthesis and Lithium Adsorption Properties of LiMn2O4 Spinel SUN Shu-ying; ZHANG Qin-hui; YU Jian-guo;    2010, 10 (1): 185-189.   Abstract （1585）      PDF （700KB）（669）       Knowledge map    Save Spinel-type ternary LiMn2O4 nanowires were synthesized via direct hydrothermal synthesis with Mn(NO3)2, LiOH and H2O2. The final low-dimensional MnO2 nanorod ion-sieve with selective adsorption property to lithium ion was prepared and further modified by acid treatment to completely extract lithium ions from the Li-Mn-O lattice. The effects of hydrothermal reaction conditions on the nanostructure, chemical stability and ion-exchange property of the LiMn2O4 precursor and MnO2 ion-sieve were systematically examined via XRD, HRTEM, SAED and lithium ion selective adsorption measurement. The results show that hydrothermal reaction conditions had the considerable effect on the structure of samples. The equilibrium distribution coefficient (Kd) of these metal ions was in the order of Li+>>Ca2+>Mg2+>Na+>K+, indicating high selectivity for Li+, but much less for Na+, K+, Ca2+, and Mg2+. The distribution coefficient for Li+ was 16770.63 mL/g, increased about 2.12 times compared with the bulky MnO2 ion-sieves (7917.49 mL/g), indicating remarkable improvement of the ion-sieve selectivity by the well-maintained nanowire structure. Related Articles | Metrics Select Suspension of Carbon Nanotubes Prepared by Non-covalent Functionalization with Surfactants HU Chang-yuan LIAO Xiao-ning LI Wen-kui ZHANG Rong-fa XIANG Jun-huai LI Ming-sheng DUO Shu-wang LI Feng-yi    2010, 10 (1): 190-194.   Abstract （2466）      PDF （413KB）（601）       Knowledge map    Save A series of carbon nanotubes (CNTs) suspensions with an initial concentration of 2 g/L were prepared by non-covalent functionalization of CNTs with SDBS, SLS, SDS, Brij35, CTAB surfactants in water with the aid of ultrasonication, respectively, and characterized. Based on the qualitative analysis via FT-IR and TGA techniques, it is concluded that surfactants are adsorbed onto the surface of CNTs after functionalization. Furthermore, the dispersion of CNTs is improved by adsorption of surfactants to CNTs, which is confirmed by TEM images. UV-Vis spectrum was used to determine quantitatively the concentration of CNTs suspensions and to investigate the stability of CNTs suspensions. The experimental results imply that the CNTs suspensions functionalized by surfactants reach equilibrium between dispersion and sedimentation of CNTs, when the concentration of CNTs suspensions no longer decreases after 240 h since suspensions have been prepared. The final concentration of CNTs suspensions changes from 1.68 to 1.84 g/L with the different surfactants used to prepare CNTs suspensions. Related Articles | Metrics Select Effect of Emulsifier on Morphology and Properties of Sodium Alginate-Paraffin Phase Change Microcapsules XIE Yan; YU Jian-ying    2010, 10 (1): 195-199.   Abstract （1279）      PDF （450KB）（624）       Knowledge map    Save Sodium alginate-paraffin phase change microencapsules were prepared by emulsification method. The effects of emulsifier type, proportion and dosage on morphology of the microcapsules were investigated. The surface morphology, chemical composition and thermal properties of microcapsules were characterized by optical microscope, SEM, FT-IR and DSC, respectively. The results show that emulsion system has greater impact on the formation of microcapsules. When the mixture of Tween-80 and Span-80 with volume ration 6:4 is taken as emulsifier, and the dosage of emulsifier is 0.12 mL/mL, the good spherical shape, small particle size, uniform distribution and good dispersion of microcapsules are obtained, and the loading efficiency is 79.14%. FT-IR spectra show that the microcapsules contain both sodium alginate and paraffin. DSC analysis reveals that the phase transition temperature of microencapsules is 52.69℃ and the latent heat 45.42 J/g. Related Articles | Metrics Select Research Progress of Bio-based Chemical 2,3-Butanediol DAI Jian-ying; SUN Ya-qin; SUN Li-hui; LI Dan; DONG Yue-sheng; XIU Zhi-long    2010, 10 (1): 200-208.   Abstract （1561）      PDF （341KB）（694）       Knowledge map    Save The progress of biotechnological production of 2,3-butanediol was reviewed, including microbial strains, sources of biomass used, fermentation processes and downstream recovery of 2,3-butanediol, and different separation techniques were compared. To reduce production cost of 2,3-butanediol, further research should be focused on screening of microbial strain, optimization of fermentation process, efficient separation techniques with energy saving, optimization of production system and exploitation of 2,3-butanediol applications. Related Articles | Metrics Select Characteristics of Flow Field in a Multi-layered Radial Reactor LI Rui-jiang CUI Chun-xia WU Yong-qiang ZHI Zi-bin    2010, 10 (2): 209-214.   Abstract （894）      PDF （563KB）（228）       Knowledge map    Save Pressure profiles in the flow channels and beds in a F3000 mm′7000 mm cold model of multi-layered radial flow reactor were measured and the flow properties of multi-layered radial reactor investigated. The results showed that when the mean square root of the pressure difference between distributing and collecting channels was smaller than 1%, the mean square root of the pressure difference between beds and maximum deviation of radial velocity along the axial direction of the beds were smaller than 5%. But when that of the pressure difference between the channels was greater than 10%, radial velocity along the axial direction of the beds became nonuniform. The flow maldistribution of the bed near the flow channel with the large change of pressure gradient was the biggest and the deviation of radial velocity on the top and the bottom of the bed was greater than 70%. The P-type flow gives the best flow distribution for the momentum recovery radial reactor and proper design of the pressure difference between distributing and collecting channels can ensure a uniform distribution in a multi-layered radial reactor. Related Articles | Metrics Select Circulating Granular Flow Partition in Pyrolytic Topping of Coal with a Circulating Fluidized Bed JI Wen-feng; DONG Li WANG Yin; NIE Wei XU Guang-wen    2010, 10 (2): 215-220.   Abstract （1078）      PDF （240KB）（283）       Knowledge map    Save The pressure difference between two particle-circulation loops in a circulating fluidized bed (CFB) for coal pyrolysis topping process was investigated to examine its effect on the partition of circulated particles. Experiments were conducted in a laboratory CFB of 12 m in height and 0.09 m in i.d. of its riser. The results demonstrated that raising the flow resistance in one side of the particle partition valve reduced the flow rate of particles into this side, implying that the pressure difference between the two circulation loops was one of the important factors affecting the performance of particle partition valve. A proposal was made and verified experimentally on how to control the pressure difference to optimize the particle partition in the valve. The realized particle partition to the low-pressure side of the partition valve varied in 0~52.4% under a total particle circulation rate of 126.9 kg/(m2×s). Related Articles | Metrics Select Fluidization Properties and Tanks-in-series Model of Silica Nanoparticles in a Horizontal Rectangular Fluidized Bed LUO Mei-fang HU Yan-jie ZHAO Ying-hong LI Chun-zhong    2010, 10 (2): 221-225.   Abstract （902）      PDF （321KB）（210）       Knowledge map    Save The fluidization characteristics of silica nanoparticles were investigated in a large-scale fluidized bed. The experimental results indicated that silica nanoparticles could be smoothly and uniformly fluidized, the incipient fluidization velocity was about 2 cm/s and the expansion ratio of bed could reach above 3. The backmixing characteristics and residence time distributions of silica nanoparticles in the horizontal rectangular fluidized bed were affected by the number of baffles, flow rate of SiO2 particles, etc. The results also showed that when two equidistant baffles were located in the horizontal rectangular fluidized bed, the solids flow pattern was apparently close to plug flow and the model parameter of tanks-in-series approached 4. On the basis of experimental results, a large horizontal rectangular fluidized bed was designed. Related Articles | Metrics Select Rheological Property of SiC-based Slurry ZHANG Zhi LU Xu-chen YAN Yan WANGTi-zhuan;    2010, 10 (2): 226-230.   Abstract （942）      PDF （289KB）（340）       Knowledge map    Save The effects of pH value, silica sol dispersant content and solid content on the rheological property of SiC-based ceramic slurry were investigated. The research results showed that Zeta potential of ceramic particles in silica sol changed significantly in comparison with that of ceramic particles in deionized water. This was caused by the adsorption of silica colloidal particles with negative charges on the surface of ceramic particles. Silica sol-dispersed slurry showed a minimum in viscosity and shear stress when pH value was around 11 and silica sol content 10%(w). The ceramic slurry showed high thixotropic behavior when solid content reached 69%(w). Related Articles | Metrics page Page 1 of 6 Total 211 records First page Prev page Next page Last page