The Chinese Journal of Process Engineering

Gas-Liquid Mass Transfer in a Slurry Bubble Column Reactor under High Temperature and High Pressure

LIU De-lin;JIN Hai-bo;TONG Ze-min

. 2004, 4(4): 289-294.

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The dynamic method was used to measure the gas-liquid mass transfer coefficient under high temperature and high pressure in a slurry bubble column reactor. The influences of the main operation conditions on mass transfer such as temperature, pressure, superficial gas velocity and solid concentration, were studied systematically. It has been found that under the conditions of temperature 293~473 K, pressure 1.0~3.0 MPa, gas velocity 0.03~0.10 m/s and solid concentration 0%~20%(w), the gas-liquid mass transfer coefficient increases with increasing pressure, temperature, and superficial gas velocity, but decreases with the increase of solid concentration. Moreover, the discrepancy of kLa in two different slurry reactors was compared. The result shows that the kLa values in a bigger reactor are a little larger than those in a smaller one at the same superficial gas velocity.

Viscosity of Kaolin Slurry from Coal Seam and the Influencing Factors

WANG Xu-hai;LU Xu-chen;LI You-chu

. 2004, 4(4): 295-299.

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The concentrated suspension of the kaolin slurry, known as a non-Newtonian fluid, possesses the shear-thinning characteristic. Negative polyelectrolytes, such as sodium polyacrylate (NaPAA), adsorbed on the surfaces of kaolin particles, can change the potential of particle surfaces, produce repulsive forces between particles, and make the kaolin particles effectively disperse each other. The effects of solid concentration, dispersant content and size of particles on the characteristics of the kaolin slurry are presented in this paper. The slurry viscosity of the kaolin increases with the increase of solid concentration and the decrease of particle size. The optimum dosage of dispersant NaPAA is about 0.3%. For the dispersant content of 0.3%, the viscosities of the slurry are 0.004 Pa×s and 0.020 Pa×s at high shear rate (729 s-1) with solid concentrations of 30%(w) and 70%(w) respectively

Water Separation of Esterification by Azeotropic Rectification with Partial Condensation

WEI Teng-you;TONG Zhang-fa

. 2004, 4(4): 300-304.

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The method of outside cooling and then generating partial condensation to offer reflow was used to realize azeotropic rectification that is effective in water separation and easy in control of reflow. By the application of esterification for n-butyl lactate, n-butyl acetate and iso-amyl acetate, it showed that this method improved the conversion of the acid by 2%~3% and reduced the loss of organic in waste water by 9%~12% compared with that of common water separator by rectification.

Effects of Ultrasound on Rate and Characterization of Copper Electrodeposition

WANG Ya-qiong;FU Xiang-lin;XU Wen-lin;LI Min;ZHANG Xiao-xing

. 2004, 4(4): 305-309.

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The current-potential curves for copper electrodeposition were measured in the presence and in the absence of ultrasound. The effects of ultrasound on the crystal orientation and surface morphology were discussed in the copper electrochemical reduction. The experimental results showed that the mass-transfer-controlled current density of the electrochemical reduction of copper ions remarkably increased in the presence of ultrasound. The influence of ultrasound on the average limiting current density decreased with increasing temperature. The average current density in the presence of ultrasound was about 14-fold than that in the absence of ultrasound at 25oC. Otherwise, the ratio of the current density with ultrasound to that without ultrasound was 8.4 at the temperature of 55oC. Ultrasound could change texture coefficient in the process of copper electrodeposition. The texture coefficient of 200 was improved with increasing time under the condition of ultrasonic irradiation. The electrodeposited grain size was also decreased in the presence of ultrasound.

Electrolytic Recovery of Nickel Powder from Acid-washing Solution Containing Nickel in Artificial Diamond Production

ZHAO Hai-peng;GUO Yi-fei;ZHANG Xiu-xin

. 2004, 4(4): 310-313.

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The treatment of acid-washing waste solution was investigated and a new method for electrolyticaly recovering nickel powder from the acid-washing waste solution containing nickel in artificial diamond production was developed. The results demonstrated that the new technique made the consistency of Ni2+, Co2+, Mn2+ in discharge liquor below 0.8, 0.2 and 0.01 mg/L, respectively, and that when the course of electrolyticaly recovering nickel powder was performed in two phase multiple electrolyte with additives and saturated cationic-exchange resin containing nickel ion, high electrolytic efficiency, high stability of composition of cathode electrolyte and high recovery efficiency of nickel could be achieved, in contrast with electrolysis in single phase electrolyte.

Recovery of Copper from Copper and Cadmium Sediment

ZENG Mao-hua;XI Chang-sheng;PENG Cui-hong;LONG Lai-shou

. 2004, 4(4): 314-319.

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The displacement of copper from copper and cadmium sediment by different metallic reducing agents was studied. The result of experiment showed that the displacement of copper by zinc was not the optimum technique, and the displacement of copper by fresh sponge cadmium was better. A new method of displacement of copper using fresh sponge cadmium was presented. The new method has some advantages which reduced the displacement of coexistence ion and prevented the release of poisonous gas effectively. Some important facts which affect reaction were researched, for example, the quantity of metallic reducing agent, the time of reaction and the temperature of reaction etc. The sponge copper was obtained from acid solution of copper and cadmium sediment which contained 2% copper by fresh sponge cadmium and the purity of sponge copper was 95%, the recovery of copper was over 99%.

Growth and Metabolism of Taxus cuspidata Immobilized in Microcapsul

SUN Qi;GE Zhi-qiang;YUAN Ying-jin

. 2004, 4(4): 320-324.

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Alginate-chitosan beads with liquid cores as a novel carrier was introduced to immobilize Taxus cuspidata cells in this work. Physiology of Taxus cuspidata cells enclosed in alginate-chitosan liquid or solid core beads were investigated. It was found that the cell viability was greater in liquid core beads than in solid ones. Liquid core beads enhance the absorption of sucrose and cell metabolism. Intracellular starch granules became gradually less according to the order of solid beads, liquid core beads and suspension. Both alginate-chitosan liquid core and solid core beads improved cell permeability, especially liquid core beads. This benefited the release of secondary metabolite and other intracellular substances into the culture medium. The synthesis and secretion of phenolics increased. Overally, the growth and metabolism of Taxus cuspidata cells encapsulated in alginate-chitosan liquid core beads were improved than in solid beads. The results show that liquid core beads is a better carrier for plant cell immobilization.

Promotion of Cell Growth and Flavonoids Production in Saussurea medusa Cell Suspension Cultures by Rare Earth Elements

YUAN Xiao-fan　;WANG Qian;ZHAO Bing;WANG Yu-chun

. 2004, 4(4): 325-330.

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Cell suspension culture of Saussurea medusa was cultivated with either Ce3+, La3+, Nd3+ or a mixture of rare earth elements (MRE) supplemented. After 20 d culture, moderate concentrations of Ce3+, La3+ and MRE can promote cell growth and flavonoids biosynthesis, while Nd3+ presented an inhibitting effect. Ce3+ at 0.025 mmol/L, gave the highest cell dry weight (17.7 g/L) and flavonoids production (942 mg/L) with both NAA and 6-BA in the culture medium. They were 34% and 67% higher than those without Ce3+ addition, respectively. Ce3+ at 0.005~0.05 mmol/L or the mixture of rare earth elements at 0.01~0.025 mmol/L, can substitute for 6-BA in promoting cell growth and the biosynthesis of total flavonoids of S. medusa while without 6-BA in the culture medium. When NAA were removed from the culture medium, none of the four rare earth elements can substitute for it in promoting S. medusa cell growth and the flavonoids biosynthesis. The kinetic curves of cell biomass, flavonoids production, residual sugar, NH4+ and NO3- concentration with or without 0.025 mmol/L Ce3+ in the culture medium were also obtained. The mechanism of the promotion effect of Ce3+ on cell growth and the biosynthesis of total flavonoids of Saussurea medusa was explained in some degree.

A New Method for Preparing Ultra-fine CaCO3 Powder via a Turbo-flow Micro-reactor and Exploration of Technological Parameters

ZHANG Yi;LI Yong-chao;TIAN Miao;MA Xiu-qing;JIN Ri-guang

. 2004, 4(4): 330-334.

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A new method is reported for preparing ultra-fine CaCO3 power with average apparent particle size of about 20~30 nm by the new turbo-flow equipment with high shearing force. The suspension of Ca(OH)2 and mixture gases of CO2 and air were dispersed well in the turbo-flow equipment, and smashed in the high-shearing container under certain pressure. This method can control the shape and size of CaCO3 powder. In this technology, the equipment is simple with small volume and high efficiency, and the fluid flows smoothly and quantificationally. The technological parameters of the new method were also explored.

Fractal Dimension to Characterize Surface Topography of Flaky Powders

JIN Yi-su;YE Hong-qi

. 2004, 4(4): 335-339.

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Surface fractal dimension was employed to describe the topography of flaky powder. DBC algorithm was chosen here to calculate the surface fractal dimension. With this algorithm computer program were tested for six kinds of flaky powder images that were obtained through microscope by digital camera under same resolution. It was found that the values of surface fractal dimension ranged from 2 to 3 and increased with the ruggedness of powder. The tiny pits or ruffles on powder surface made great contribution to the value as fractal dimension. The results obtained show that the surface fractal dimension reflects to some degree the surface roughness. It is valuable to apply the surface fractal dimension to the preparation and application of flaky powder as a description of surface roughness.

SEM Morphology and Tensile Strength of Nickel Foil by Electrodeposition

LIU Yu-xing;GUO Zhan-cheng;LU Wei-chang;DUAN Yue

. 2004, 4(4): 340-346.

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The process conditions in the electrodeposition of nickel foil were studied. The SEM morphology of the surface and section of nickel foil was observed and associated with tensile strength. The results showed that the limiting current density could be greatly increased by dynamic electrodeposition. When the flow velocity was about 1.2 m/s the limiting current density reached 0.9 A/cm2. The SEM morphology showed that the grain size of nickel foil by dynamic electrodeposition was less than that by static condition. The grain size was decreased to about 1 μm. The section morphology showed that the crystal size of pure nickel foil grew gradually along the direction of thickness during electrodeposition. When adding additive, the surface of nickel foil was much brighter. The tensile strength was greatly increased when adding 5 g/L saccharin. The maximum tensile strength could reach 900 MPa.

Preparation of Microporous PVC and in Situ Composite Technology of PVC/CaCO3

XIONG Chuan-xi;DONG Li-jie;WANG Qing-gang;WANG Tao;LU Sheng-jun;XIANG Ni-ya

. 2004, 4(4): 347-351.

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This article describes the preparation of PVC/nanometer CaCO3 composite particles by an in situ method. Porous polyvinyl chloride (PVC) particles were swelled by compound solvent with foaming agent 2,2￠-azo- bis-iso-butyronitrile (AIBN). When heated at 112oC, PVC particles were foamed because AIBN decomposed to gas. When the volume percentage of cyclohexanone in compound solvent reaches 11.7%, the porosity of microporous PVC increases to the maximum of 35.9%. Microporous PVC, Ca(OH)2 and some additives were dispersed uniformly in water and then aerated with CO2, thus PVC/nano-CaCO3 composite particles was prepared by this in situ method. Chemical analysis indicated that the maximal content of synthesized CaCO3 reached 20%. SEM micrographs show that microporous PVC particles had many cavities and nanometer CaCO3 were filled in these cavities at the same time. It is inferred that nanometer CaCO3/PVC mixture toughens and reinforces PVC.

Synthesis and Characterization of P-type Zeolite Membrane on a Porous a-Al2O3 Tube

ZHU Gang;WANG Jin-qu;LU Jin-ming

. 2004, 4(4): 352-357.

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The influence of gel alkalinity on the synthesis of zeolite P and its membrane was examined in detail, which show the decisive effect of gel alkalinity on the structure of the zeolite synthesized and the optimum gel alkalinity for the synthesis of zeolite P is given. Zeolite P membranes were hydrothermally synthesized in situ on the outer surface of a porous a-Al2O3 support tube with a length of 25 cm and pore size of 3~5 mm. XRD and SEM characterization of the as-synthesized membrane show that the as-synthesized membrane is a typical zeolite P membrane, with no apparent defects on the membrane surface, where the zeolite crystals grow interlinkedly and compactly, and that the outer surface of the support tube is completely covered with P crystal layers with a thickness of about 10~12 mm. At 25oC, H2 and N2 single component permeation tests of the as-synthesized membrane give the permeability up to 10-6 magnitude and the H2/N2 selective factor between 3.19~3.33.

Production of High Quality Carbon Black by Gasification and Pyrogenation of Industrial Propane

ZHANG Wei;XIE Hong-yong

. 2004, 4(4): 358-361.

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High purity carbon black of 10~40 nm was synthesized by industry propane/O2 flame and propane/air flame in both gasification regime and pyrolysis regime. The effect of fuel/O2 ration was investigated on the DBP and pH values, particle size and morphology. The experimental results show that the carbon black synthesized in gasification regime is suitable as filler materials, whereas, the carbon black synthesized in pyrolysis regime has higher performance in conductivity and wear. And the optimal conditions for the highest yield of carbon black were obtained to be C3H8 1.29′10-3 mol/s, air rate 1.512′10-2 mol/s.

Preparation of Magnetic Nanoparticles and Its Application to Enzyme Immobilization

LIU Wei;BAI Shu;SUN Yan

. 2004, 4(4): 362-366.

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Lauric acid-stabilized magnetic nanoparticles were prepared and used for enzyme immobilization. The Fe3O4 magnetic nanoparticles were characterized by transmission electron microscopy and magnetic measurements. The observations indicated that the particles were superparamagnetic. Magnetic sedimentation of the nanoparticles was achieved within 0.6 min in organic solution, 200 times faster than the gravitational sedimentation. Lauric acid provided a hydrophobic interface to the immobilized lipase, and the conformational changes induced by interacting with the hydrophobic interface yielded an "open structure" of the lipase. CRL was immobilized to the magnetic carrier with a specific activity of 718 U/g, 1.8 times higher than the free lipase containing the same protein quantity. The pH dependencies of the immobilized and free lipases were investigated and the optimum pH for them were determined. Moreover, activity amelioration and stability of the immobilized lipase for the hydrolysis of olive oil was observed.

Extraction of Volatile Oils from Asarum Heterotropoides by Supercritical CO2 and Microwave-aided Techniquesand Microware

ZENG Hong-yan;JIN Yong-zhong;ZENG Mei-xia;WANG Ping;BAO Luo-tao

. 2004, 4(4): 367-371.

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The volatile oils were obtained with the supercritical CO2 and microwave methods to search for the optimum extraction conditions. The uniform design of experiment was used to optimize the supercritical CO2 extraction conditions. The optimal conditions were determined: pressure 16 MPa, temperature 32oC, CO2 flow rate 20 kg/h and time 80 min. The optimum conditions of the microwave extraction were obtained by orthogonal experiment: radiation time 200 s, microwave power 720 W, volume of solvent 300 ml, volume of washing solvent 30 ml. The volatile oils were obtained by supercritical CO2, microwave and steam distillation, and the extraction rate was 3.78%, 5.46% and 1.62% respectively. The results showed that the extraction rate of microwave extraction was higher and its process was simpler, but the quality of the volatile oil was worse than those extracted by supercritical CO2 and steam distillation.

Investigation on Pressure Field in Bubbly Flow with Cell-ensemble Averaging

XU Zhao-feng;LUO Rui;YANG Xian-yong

. 2004, 4(4): 380-384.

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Bubbly flow is a basic two-phase flow problem and is usually analyzed using two-fluid models. The closure laws are very important and determine accuracy of two-fluid models. The previous closure laws were derived based on the potential flow assumption, such as the averaged pressure difference, pli-pl, between the interface and the liquid phase. However, the pressure difference is affected by fluid viscosity, wake of bubbles, bubble deformation, and so on. In this paper, taking fluid viscosity into consideration, the pressure difference is constituted using cell-ensemble average. The new formula can be applied for"laminar"bubbly flows where the relative Reynolds number is small and therefore the influence of bubble wakes on the pressure field is negligible. The new formula gives a larger result than the potential one, which agrees with the empirical data for"laminar"bubbly flows. The new formula can not be applied for turbulent bubbly flows, because the pressure field is considerably affected by wakes of bubbles. So it is necessary to investigate the effects of wakes of bubbles to construct a pressure difference formula for turbulent bubbly flows.

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