The Chinese Journal of Process Engineering

One-dimensional Modeling of Multiple-unit Pneumatic Transport Reactor for Producing Titanium Tetrachloride — I. Mathematical Model Tetrachloride I. Mathematical Model

XU Cong;YUAN Zhang-fu;XIAO Wen-ming

. 2004, 4(6): 481-489.

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The multiple-unit pneumatic transport reactor is an innovative reactor, which consists of multiple units of a pneumatic transport riser and a dense-phase turbulent bed. It can be used as a reactor for gas-solid reaction system to avoid adhesion and agglomeration and enhance mass transfer rate. In this paper, a one-dimensional model has been established to describe the behavior of multiple-unit pneumatic transport reactor for producing titanium tetrachloride, in which the bubble assemblage model is used to calculate the reactant gas mass transfer rate from the bubble phase to the emulsion phase, and the particle-size distribution along vertical axis is determined by a population balance. Some important parameters such as reaction temperature, composition of solid particles, composition of gas phase, elutriation rate of solid and efficiency of reaction etc. can be solved from the model.

Numerical Solution of Convection-Diffusion-Nonlinear Chemical Reaction Equation in Fixed Beds

LI Ming-chun;XU Zeng-he;ZHAI Yu-chun;TIAN Yan-wen

. 2004, 4(6): 490-495.

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Considering that the overall rate of a single pellet is co-dominated by intra-particle diffusion and chemical reaction, the overall rate of representative-element volume was derived from that of a single pellet. Then, the convection-diffusion-nonlinear reaction equation was established, and solved numerically. Taking the indirect reduction of iron ores as a case, the mass transfer, reaction and conversion process occuring within one-dimensional fixed bed was discussed. The results show that the size of pellets and convection velocity influence notably reaction and conversion process. Their influence can be measured by the Thiele module and Peclet module respectively. Because the Thiele module depends on L2 positively, and Pe* does on L positively, the length of reactor L is an important factor to influence the performance of reactor itself. The effect of convection on reaction and conversion descends, and gaseous conversion increases with increasing ratio of y/Pe*.

Hydromechanical Performance Measurement and Comparison of Four Species of Minitype Packings

CHANG Yan-long;FENG Qing-hua;ZHANG Kun;YAN Xiao-hua

. 2004, 4(6): 496-501.

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In a F30 mm packing column, the hydromechanical performance was determined and compared for the four species of high-efficiency mini-packings, such as q network ring, etc. The uniform pressure-drop formula and liquid holdup formula were derived for the mini-packings with diameters from 1.5 to 10 mm. And their errors were calculated, the average error is less than 6% except connon ring packing which has an unideal configuration and a lower specific surface area. According to the errors, the formula derived better fits the packings with the specific surface areas more than 2000 m2/m3. Compared with the large-scale bulked packing, the mini-packing has a lower pressure drop which increases by 1.5 power of gas phase loading factor under the flooding point and a smaller liquid holdup which increases with 0.3 power of Froude number, so it has a better hydromechanical performance. The mini-packing is first selected for the separation of liquid fine chemical products because of its excellent performance.

Synthesis of a Novel Boron-specific Chelating Resin an Its Adsorption to Boron from Salt Lake Brine

WANG Li-na;QI Tao;LI Hui-quan;ZHANG Yi

. 2004, 4(6): 502-507.

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A novel boron-specific chelating resin was synthesized by the functionalization of poly(glycidyl methacrylate-co-trimethylolpropane trimethacrylate) [poly(GMA-co-TRIM)] with N-methyl-D-glucamine. The structures of polymer matrix, resin, and boron-loaded resin were confirmed by infrared spectroscopy. The behavior of the resulting resin in adsorption of boron from salt lake brine was investigated. The results show that the properties of polymer matrixes especially the GMA molar fraction in polymers have strong impact on the uptake capacity of boron. The resin exhibits high selectivity, large uptake capacity and high adsorption rate towards boron in salt lake brine. The maximum uptake capacity of boron reaches 0.6 mmol/g. Boron can be eluted thoroughly from the resin by 1.0 mol/L hydrochloric acid. The adsorption kinetics is well explained by a particle diffusion model.

Preparation of Methyl Methacrylate by One-step Oxidative Esterification of Methacrolein

LI Gui-hua;ZHANG Suo-jiang;LI Zeng-xi;LI Ming-xiu;ZHAO Wei

. 2004, 4(6): 508-512.

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The two-step reaction for preparation of methyl methacrylate (MMA) from methacrolein (MAL) was simplified to a one-step oxidation-esterification reaction, a new catalyst was prepared and applied to this reaction in pending patents. Under the conditions of continuous stirring and atmospheric pressure the effects of reaction conditions on MAL conversion and MMA selectivity were systematically investigated. The results indicated that the catalyst Pd5Bi2Pb1Fe1/CaCO3 was active and could be used to the reaction of methacrolein one-step oxidation-esterification. The most appropriate reaction conditions are temperature 50℃, O2 velocity 6 mL/min, nMeOH/nMAL=75, catalyst 2.4% and reaction time 60 min. At the above conditions the MAL conversion and MMA selectivity reached up to 99.4% and 95.7% respectively. The apparent reaction kinetics for MAL was 1.1 order. The activation energy was 19.3 kJ/mol. The results confirm the feasibility of the new green technology for production of MMA.

Production and Application of Hollow Capsules Templated on Melamine-formaldehyde Microspheres

LIU Ya-jun;ZHU Yi-hua;ZHANG Su-qiu;YANG Xiao-ling

. 2004, 4(6): 513-518.

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Uniform hollow capsules were produced by the layer-by-layer electrostatic self-assembly technique. The core-shell microspheres were prepared by alternately depositing negative and positive polyelectrolytes onto the weakly-crosslinked MF microspheres which were used as solid templates, then the templates were decomposed by 0.1 mol/L hydrochloric acid to get hollow capsules. The loaded drug amount and controlled release from the capsules were tested using Dexorubicin hydrochloride as the model medicine. The result shows that the loaded drug amount in the capsules is 27.07 μg/mg and capsules can slow down the release of Dexorubicin remarkably.

Characteristics of Bioleaching of Zijin Copper Ore by Acidianus brierleyi

LI Cong-ying;MENG Chun;LIN Hui;CHEN Shou-qing;SUN Jie;GUO Yang-hao;ZOU Lai-chang

. 2004, 4(6): 519-524.

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Characteristics of Zijin copper ore bioleaching by Acidianus brierleyi were studied. Experriments estimated the effects of initial pH, inoculum and solid concentration on fraction of leached copper, experimental data showed that the optimal opertating conditions were pH 2.0, 10% inoculum and 5% solid concentrations. The mechanism of bioleaching of Zijin copper ore by Acidianus brierleyi was discussed, the bioleaching of Zijin copper ore by Acidianus brierleyi was the result of a complex process of direct microbial attack and chemical oxidation by the ferric iron. The bioleachig capability of Acidianus brierleyi(65oC) with the Zijin copper ore was strong, 1.7 times as high as that of Thiobacillus ferrooxidans (31℃). Acidianus brierleyi has a promising perspective of industrial application.

Process Conditions of Extraction of Xanthan gum via Ultra-filtration and Alcohol-precipitation

ZHU Sheng-dong;LEI Yun-zhou;TONG Hai-bao;CHEN Da-chang;XIE De-cheng

. 2004, 4(6): 525-530.

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The effect of three different pretreatment methods on xanthan gum yield and quality was examined and the dilute multiple and diatomite loading in diatomite—filtration pretreatment were optimized. The effect of membrane, velocity on the membrane surface, temperature, pressure and gum concentration on the water permeation flux in the ultra—filtration was investigated and the best ultra—filtration conditions were determined. The effect of solvents, loading of solvent and pH on alcohol—precipitation of xathan gum was studied and the optimal alcohol—precipitation conditions were obtained.

Analysis of Reactions for External Desulphurization of Molten Iron with Mg/CaC2 Desulphurizer

XU Yang;SUN Ben-liang;LI Cheng-wei;YU Kui-feng

. 2004, 4(6): 531-535.

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The desulphurization experiments were carried out in 15 kg heats of molten iron. It was found through the experiments that the desulphurization rates could be improved by predeoxidation with an addition of aluminium. Before injection, the initial oxygen content could be dropped to 5 10 6 by addition of aluminium, accelerating desulphurization rate, and the sulphur content could be dropped to 4 10 5. The experiments without adding aluminium showed that the ultimate oxygen content and sulphur content were dropped to 8 10 6 and 5 10 5 respectively, because both Mg and CaC2 have the function of deoxidation.

Cluster Analysis and Visualization Enhanced Genetic Algorithm —II. Analysis of Cases and Validation

SUN Xiao-jing;WANG Ke-feng;YAO Ping-jing

. 2004, 4(6): 536-543.

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This paper validated that the Cluster Constrained Mapping (CCM) can keep the "topological" information of the points in the reduced dimension map by comparing the cluster results obtained using the K-means algorithm. The enhanced GA proposed in Part I was applied to three constrained optimization cases. The results show that the combination of visualization, cluster analysis and genetic algorithms can help users to participate in selecting appropriate parameters of clusters, and the combination of a computer and the user is more powerful than either alone, which is an effective process optimal design tool with high solution quality and consistency. In the new cluster analysis method, the data are visualized by CCM that provides immediate direct information about the feasible domain, and the user is directly involved in determining the parameters for the cluster analysis and increasing the effectiveness of feasible regions discovery by visual interaction; the obtained knowledge is visualized by Parallel Coordinate Systems (PCS), thus the user has a deeper understanding of the feasible regions. It is clear that in most cases the proposed IGA based on the combination of visualization and cluster analysis has performed not only with the high efficiency (in terms of getting closer to the best-known solution) and with more robustness (in terms of the number of GA runs finding solutions close to the best known solution), but also with providing more information about the feasible regions for the user to understand the model and accept the optimal results.

Simple Stoichiometric Reactions

HU Shan-ying;LI Ming-heng;LI You-run;SHEN Jing-zhu

. 2004, 4(6): 544-548.

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It is a key step for reducing waste generation in chemical processes to design optimal reaction paths. In this paper, a new conception of simple stoichiometric reaction is proposed for the reaction path synthesis problem. A simple stoichiometric reaction is the reaction in which the freedom of atomic matrix formed by reactants and resultants is 1 and also fulfils the atomic balance equations. The simple stoichiometric reactions greatly reduce the number of reaction equations, so as to reduce lots of search space in reaction path synthesis. All simple stoichiometric reactions can be obtained by mathematical transformation for atomic matrix of a reaction system, and the best one is then easily to be chosen. This conception is an important basis for much more complex problems.

Application of the Soft Measurement Technology to Optimization System of Boiler Burning at Power Station

LI Zhi;CAI Jiu-ju;XU You-ning;GUO Hong

. 2004, 4(6): 549-553.

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The unburned carbon content in the fly ash of a 200 MW unit coal burning boiler at Fuxin Power Plant is tested and data specimens have been gained. By taking back propagation (BP) neural network based on Levenberg-Marquardt (LM) algorithm, the soft measurement model of the unburned carbon content in fly ash is established. The measurement system of the unburned carbon content in the fly ash is made up of the soft measurement model. With the help of it, the optimization system of utility boiler combustion has been developed, which is used to realize optimal adjustment of a 200 MW unit coal burning boiler at Fuxin Power Plant.

Photosynthetic Characteristics of Prorocentrum Minimum and Its Nutrient Uptake at Different Nitrogen and Phosphorus Levels

SHI Yan-jun;HU Han-hua;MA Run-yu;CONG Wei;CAI Zhao-ling

. 2004, 4(6): 554-560.

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The uptake of nitrate and phosphate by Prorocentrum minimum and its growth and photosynthesis characteristics were studied by laboratory culture. The results indicated that the maximum specific growth rate (0.46 d 1) was observed at low nitrate level (0.0882 mmol/L NaNO3), the maximum yield (54900 cell/mL) occurred at middle nitrate level (0.882 mmol/L NaNO3), which increased by 7.2% and 20.1% respectively compared with those at low nitrate and high nitrate levels. The cell yield and specific growth rate increased with increasing phosphate concentrations in culture, and the maximum cell yield (57400 cell/mL) and the maximum specific growth rate (0.45 d 1) were recorded at high phosphate concentration (0.108 mmol/L KH2PO4). The higher chlorophyll a-specific and cell-specific light-saturated photosynthetic rates (Pmchl a and Pmcell) and higher light intensity at which photosynthesis is initially saturated were observed at high nutrient levels. The cells grown in the cultures with low nitrate and high nitrate levels showed the same values of apparent photosynthetic efficiency ( chl a and cell). The maximum chlorophyll a-specific apparent photosynthetic efficiency ( chl a) was obtained at high phosphate level. The experimental results showed that the lower ratio of N/P with sufficient nitrate had a positive effect on the propagation of Prorocentrum minimum.

Effect of Glucose as Cosubstrate on 1,3-Propanediol Fermentation by Klebsiella pneumoniae

CHENG Ke-ke;LING Hong-zhi;ZHANG Li-li;SUN Yan;LIU De-hua

. 2004, 4(6): 561-566.

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The effect of glucose as cosubstrate for the seed culture and fermentation of 1,3-propanediol by Klebsiella pneumoniae with glycerol as substrate was investigated. The results showed that the mixed substrate of glycerol and glucose for the seed culture could shorten the seed culture period. When adding glucose as cosubstrate, the productivity and yield of 1,3-propanediol were increased greatly in batch and fed-batch fermentation, but different glucose feed strategies could lead to different results. Compared with the 1,3-propanediol fed-batch fermentation production with glycerol as the only substrate, the 1,3-propanediol concentration, productivity and yield increased by 41.2%, 38.6% and 8.3% respectively when 5 g/L glucose was added to the initial fermentation media and a mixture of glycerol and glucose was fed during 4 40 h.

Effect of ATP Addition on 1,3-Propanediol Biosynthesis from Glycerol by Klebsiella pneumoniae

ZHANG Yan-ping;RAO Zhi;DU Chen-yu;LI Chun;CAO Zhu-an

. 2004, 4(6): 567-571.

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Biosynthesis of 1,3-propanediol (1,3-PD) attracted much attention recently. Glycerol dehydratase, the key enzyme of the biosynthesis of 1,3-PD from glycerol, tends to undergo mechanism-based inactivation by glycerol during catalysis, and the inactive dehydratase was rapidly reactivated in the presence of AdoCbl, ATP and Mg2+ (or Mn2+). In this paper, the effect of ATP on biosynthesis of 1,3-PD from glycerol by Klebsiella pneumoniae L1 was investigated. Although bacterium growth was inhibited with ATP addition in fermentation medium, the capability of 1,3-PD biosynthesis by K. pneumoniae cells per OD was increased. By addition of 0.6 0.8 g/L ATP, the reductive metabolism of glycerol was strengthened and the titer of 1,3-propanediol increased by 50 70 . The yield of 1,3-PD was also improved, especially in the latter phase of fermentation compared with a rapidly decreased yield in control experiment. For seeing about the simulative effect of ATP on 1,3-PD biosynthesis, rest K. pneumoniae cells were used in this work. It indicated that ATP could reactivate the inactive glycerol dehydratase effectively, and the activity of dehydratase would not decrease observably during repetitious reactivation. ATP was an important factor affecting the catalysis activity of glycerol dehydratase and even the biosynthesis of 1,3-PD from glycerol by K. pneumoniae. Keeping ATP in a higher concentration in the fermentation system was a logical approach to improve 1,3-PD biosynthesis.

Enzymatic Synthesis and Purification of Alkyl Xylosides and Xylobiosides

ZHU Yun-ping;JIANG Zheng-qiang;LI Li-te;LI Dao-yi;SHEN Ying-jie

. 2004, 4(6): 572-576.

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Phase Diagram Analysis of a New Cleaner Process for Making Chromium Trioxide and Potassium Nitrate Simultaneously

CHEN Heng-fang;LI Zuo-hu;ZHANG Yi;LI Hui-quan

. 2004, 4(6): 577-582.

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