Table of Content

20 April 2013, Volume 13 Issue 2

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流动与传递

Simulation Study on the Best Tertiary Air Velocity of Coal Blend Combustion in a Calciner

XU Shun-sheng LI Luo-jun HUANG Ri-sheng DENG Bo ZHANG Li-na SHI Yong-bin

. 2013, 13(2):  181-185. 

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In order to solve the problem of coal blend ineffective combustion in a 5500 t/d triple-spouting calciner, using FLUENT software and applying two-step competitive reaction model and two mixture fraction method, the fields of velocity, temperature and composition in the calciner were studied by numerical simulation under different tertiary air velocities. The influential law of tertiary air on the combustion of coal blend was obtained, and the simulation results were verified. The simulation results show that the results computed by the two-mixture-fraction and PDF calculation are in accordance with the real combustion of coal blend in the calciner. When the third air velocity is 26 m/s, the combustion zone of coal blend accounts for 2/3 of the calciner, the maximum combustion temperature of pulverized coal is 1940 K and the burnout rate of pulverized coal 95.45% in the calciner. The temperature distribution can meet the requirements of raw material decomposition, and slagging phenomenon can be avoided.

Theoretical Analysis on the Influential Factors of Bubble-Particle Collision Efficiency in Hydrocyclone Flotation

HAN Yan-he CHEN Jia-qing SANG Yi-min RUAN Xiu-li WANG Chun-sheng WANG Jian-wen ZHANG Ming

. 2013, 13(2):  186-190. 

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On the basis of the bubble-particle collision efficiency model in the contact zone of cyclone flotation, the effects of physical property parameters, operating parameters and structural parameters on the collision efficiency were investigated. The results show that physical property parameters such as disperse phase size and density, operating parameters such as bubble size and tangential velocity and structural parameters such as equivalent hydrocyclone diameter have great effect on the collision efficiency. In the hydrocyclone flotation process, the collision efficiency increases with the increase of disperse phase size, and decreases with the increase of bubble size and disperse phase (oil droplet) density. When the disperse phase size is less than 0.02 mm, which is mainly dissolved oil, the collision efficiency increases with the decrease of tangential velocity, and increases with the increase of equivalent hydrocyclone diameter. However, when the disperse phase size is over 0.02 mm, the effects of tangential velocity and equivalent hydrocyclone diameter on the collision efficiency are exactly opposite of a bond. What removed by cyclone flotation is mainly non-soluble oil (oil drop diameter >0.02 mm). The densification of hydroclone flotation can improve the bubble-particle collision efficiency, achieving high efficiency separation.

反应与分离

NO Reduction Characteristics of Biomass Pyrolysis Products in a Drop-tube Reactor

YANG Wu WANG Yin; SONG Yang YAO Chang-bin LIU Yue-jin XU Guang-wen

. 2013, 13(2):  191-196. 

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A continuous drop-tube furnace was used to simulate the combustion conditions in the reburning zone of circulating fluidized bed decoupling combustion, and a series of experiments was conducted to study the NO reduction characteristics of pyrolysis products of distilled spirit lees, char, tar and pyrolysis gas, in terms of the specific NO reduction efficiency (hE) defined against the unit-mass flow reductant. The results indicated that with increasing of reaction temperature from 800 to 1050℃, hE of char, tar and pyrolysis gas increased. The optimal residence time for the possibly highest hE was 3.4 s for tar and char reductants. With increasing of NO concentration from 400′10-6(j) to 1000′10-6(j) in the reactant gas, the specific NO reduction efficiency decreased, but the reduced absolute NO amount increased for all the pyrolysis products. Increasing the O2 concentration in the reactant gas caused hE to decrease for char, to increase for pyrolysis gas and a parabola variation with increase first and then decrease for tar. At the O2 concentration of 1.63%(j), hE for tar was highest and reached 60.1%. This study demonstrated that unit-mass flow reactant tar enabled the highest NO reduction in comparison with char and pyrolysis gas.

Extraction of Rare Earth Ions by Emulsion Liquid Membrane from Acidic Leaching Solution of Phosphorus-containing Ore

XIE Zi-nan CHEN Qian-lin ZHAO Li-jun

. 2013, 13(2):  197-201. 

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Lanthanum and cerium ions riched phosphate ore in Zhijin was dissolved by hydrochloric acid, then extracted by emulsion liquid membrane. This liquid membrane system contained di(2-ethylhexyl)-phosphate as carrier, sorbitol anhydride or polyisobutylene succinimide as surfactant, sulfonated kerosene as solvent and hydrochloric acid as strippant. The effects of carrier and surfactant to emulsion on recovery of rare earth ions were studied. Separation and extraction of rare earth ions under different pH values were also examined. The results showed that the optimum concentrations of carrier and surfactant were 12%(j) and 4%(j) respectively, with the increase of pH value in external aqueous phase, the extraction rate of rare earth ions with emulsion liquid membrane increased. When the concentration of rare earth ions was 100 mg/L, and pH=1 in external aqueous phase, their extraction rate was up to 79.93%.

New Extraction Process of Vanadium from Stone Coal by Acid Curing

WAN Hong-qiang NING Shun-ming SHE Zong-hua XING Xue-yong FENG Zhi-min

. 2013, 13(2):  202-206. 

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Using the vanadium-containing stone coal from south China as raw material, the acid curing process of vanadium recovery was studied. The effects of process parameters, such as granularity, water addition, dosage of sulfuric acid, curing temperature, curing time and leaching solution, on the leaching of vanadium were examined, as well as the behavior of H2O in the acid curing process. The optimal conditions were obtained as follows: ore granularity 125 mm, water addition 10%(w), dosage of sulfuric acid 20%(w), curing temperature 140℃, curing time 3 h, leaching time 2 h, and ratio of liquid to solid 1.5 mL/g. Under the optimum conditions, the leaching rate of vanadium was 87.8%. The structure of micas mineral in the ore was destroyed, and SiO2 formed in the curing, which was difficult to digest. The concentration of SiO2 in leaching solution was 0.09 g/L, being beneficial to subsequent processing.

Effect of Extracellular Polymeric Substances on Flocculation-Sedimentation during Domestic Wastewater Treatment

MA Xing-guan JI Wen-juan JIANG Tao XUE Xiang-xin YANG He FU Jin-xiang

. 2013, 13(2):  207-211. 

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The effects of concentrations of protein and polysaccharide, mass ratio of protein to polysaccharide (P/C) and total quantity of EPS on flocculation-sedimentation were studied using an integrated membrane biological reactor (IMBR) during domestic wastewater treatment at room temperature. The relationships between influential factors and turbidity as well as sludge volume index (SVI) were established by binomial nonlinear regression equations, and the corresponding flocculation-sedimentation mechanism was analyzed. The results show that increasing the concentration of EPS worsens the flocculation and sedimentation with the higher nonlinear related coefficient (R2) being 0.683 and 0.785, respectively. With the increase of concentrations of protein and polysaccharide, both turbidity and SVI exhibit ascending tendency, demonstrating the depressed flocculation-sedimentation. The turbidity decreases while SVI displays a relative steady with increasing of P/C. And the polysaccharide has a greater effect on flocculation-sedimentation than protein. Based on the DLVO theory, the functions of EPS and its constitutes were analyzed. It is explained that the flocculation-sedimentation mechanism originates from the competitive result between long range van der Waals force and double-layer repulsion.

Treatment of Wastewater Containing Chromium Ion by Intermittent Foam Fractionation

WANG De-jin SHEN Wen-hao

. 2013, 13(2):  212-216. 

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Using a homemade inner circulating foam fractionation column, simulated wastewater containing Cr ion was treated and compared with a conventional bubble tower in its separation efficiency, and the influential factors pH value, Fe(NO3)3, concentration of sodium dodecyl sulfate (SDS), gas flow and separation time were examined. The results show that the circulating flotation column separation efficiency is higher within 12 to 35 min, Cr ion concentration reaches 0.6 mg/L in the fractionation in 35 min, but 10 mg/L in the conventional bubble column. The optimum operating conditions of inner loop flotation column are obtained, for the initial Cr ion concentration of 20 mg/L in waste water, under pH 5.5, SDS 100 mg/L, Fe(NO3)3 60 mg/L, and gas flow rate of 800 mL/min, the treatment effect is preferable. The bubble entrainment rate is about 10%, and Cr(III) removal rate over 97%.

过程与工艺

Pyrolysis Kinetics of Activated Sewage Sludge in Preparation of Sewage Sludge-based Activated Carbon

SHAO Rui-hua FANG Ping

. 2013, 13(2):  217-223. 

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Pyrolysis mechanism of activated sewage sludge in preparation of sewage sludge-based activated carbon was studied by using non-isothermal TG and non-isothermal pyrolysis kinetics. The non-isothermal kinetic parameters and mechanical functions were analyzed by Flynn-Wall-Ozawa and Coats-Redfern equations. Pyrolytic kinetics parameters were studied respectively before and after DTG peak in low-temperature pyrolysis and mesothermal solution stages. The most probable pyrolysis mechanism function of activated sewage sludge was determined by double extrapolation method. The results showed that the kinetic parameters (reaction activation energy E and Arrhenius factor A) before and after DTG peak in low temperature pyrolysis stage are Ea?0=32.53 kJ/mol, lnAb?0=4.37, Ea?0=39.7 kJ/mol, lnAb?0=3.94 (a, sample conversion rate, b, heating rate) respectively, and Ea?0=130.24 kJ/mol, lnAb?0=19.10, Ea?0=150.14 kJ/mol, and lnAb?0=17.13 before and after DTG peak in middle temperature pyrolysis stage. Pyrolysis mechanism of activated sewage sludge meets the four-stage pyrolysis mechanism model, Mampel-Power rules (n=1/3), three-order chemical reaction, two-order chemical reaction and Mampel-Power rules (n=3/2).

Preparation of Al- and K-containing Products from Associated Alunite Ore Tailings

QIN Ming ZHAO Wei XUE Tian-yan YU Zhi-hui ZHAO Hong-xin; LI Jie SONG Jing GUO Qiang RUAN Ren-mang QI Tao

. 2013, 13(2):  224-229. 

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A medium temperature calcination-low concentration acid leaching process was introduced to treat the associated alunite ore tailings. After calcination of the tailings at 700℃ for 3 h, and following leaching at 90℃ for 3 h in 10% sulfuric acid system with the acid/ore ratio of 6 mL/g, the leaching rates of Al and K reached 83% and 93%, respectively. Alum and aluminum sulfate hydrate crystals were obtained through natural and evaporation crystallization. The recovery rate of alum and aluminum sulfate hydrate crystals was up to 65%. This work provides a method to separate aluminum and potassium products preliminarily under the premise of reduction of energy and acid consumption.

Dissolution of Al2O3 in VOD Refining Slag

SU Li-juan LI Guang-qiang LI Wei YUAN Gang LI Peng; CHEN Zhao-ping

. 2013, 13(2):  230-235. 

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The absorption rate of Al2O3 in CaO-SiO2-Al2O3-MgO-CaF2 VOD refining slag is simulated by the dissolution rate of rotating Al2O3 rod in the slag. The effects of various factors on its dissolution rate were examined. The results show that the limiting step of Al2O3 dissolution is its mass transfer to molten slag. The rate increases with increasing of the rotating angular velocity of Al2O3 rod. The dissolution rate in the slag with the basicity of 4 and Al2O3 content 25% increases from 19.2′10-3 to 29.2′10-3 g/(cm2·min) with increasing of the rod rotation angular velocity from 100 to 200 r/min at 1600℃. Increasing the basicity of refining slag reduces the saturation solubility of Al2O3 in the slag. When the basicity of refining slag increases from 3 to 5, the dissolution rate of Al2O3 decreases from 30.7′10-3 to 9.4′10-3 g/(cm2·min) at 1600℃. When the basicity of refining slag is 4, with the initial Al2O3 content in slag increasing from 15% to 35%, the dissolution rate from 36′10-3 down to 25.8′10-3 g/(cm2·min) at 1600℃. Increasing the temperature and decreasing the basicity of slag are beneficial to increase of the Al2O3 absorbability. The dissolution activation energy of Al2O3 in dissolving process is obtained, which increases with the initial Al2O3 content in the refining slag.

Reduction Progress of Vanadium Titano-magnetite with Coal Powder

CHEN Shuang-yin GUO Peng-hui CHU Man-sheng GUO Peng-hui HAN Yuan-ting

. 2013, 13(2):  236-240. 

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对煤粉还原钒钛磁铁矿过程中产生的铁氧化物和钛铁化合物进行热力学分析，得出工艺还原过程中的反应热力学数据，进一步采用高温炉在还原温度1350℃、配碳比1.0、还原煤粒度小于75 mm的条件下，考察还原时间对工艺指标的影响和还原过程，得出不同还原时间下产物的定量结果和物相成分. 结果表明，还原时间为60 min时，还原产物的全铁、金属铁、金属化率均达最大值，分别为68.60%, 65.81%和95.93%，钒钛磁铁矿中铁氧化物的还原过程为Fe2O3→Fe3O4→FeO→Fe，钛铁化合物的还原过程为Fe2TiO5→Fe2TiO4→ FeTiO3→FeTi2O5.

Effect of Aluminum Plant Waste Slag on the Melting Characteristics of Gasification Briquette with Low Ash Fusion Temperature

LIN Hua-feng LIN Rong-ying LIN Bo ZHENG Fu-bao

. 2013, 13(2):  241-245. 

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The effect of aluminum plant waste slag on the melting characteristic of Fujian Jianxing coal (JX), Yongan coal and Chuanghong coal with low ash fusion temperature was studied under the mild reducing atmosphere. The change of mineral compositions under various temperatures before and after addition of the waste slag into JX was examined by XRD and SEM-EDX. The results show that low-temperature eutectic mixtures formed over 1000℃ is the major reason for low ash fusion temperature of JX. The coal ash fusion temperature is obviously increased by adding the waste slag .While the added mass of waste slag is 6% (ash as reference), the ash softening temperature (ST) of JX can be increased to over 1250℃ to meet the ash fusion temperature requirements of the gasifier solid deslagging process. Adding the waste slag, mullite phase forms in JX ash above 1000℃. The mullite phase plays a skeleton effect on ash, and delays the formation of low-temperature eutectic mixtures, thereby improving the ash melting point.

Experimental Study on Reduction of Cr-containing Materials in Iron Bath with C and H2

FU Hui-long NIU Shuai CHEN Wen-bin HONG Xin

. 2013, 13(2):  246-249. 

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Low-grade chromium ore and stainless steelmaking dust were reduced with carbon in iron bath, H2 was also used as reductant. The results showed that under an appropriate reducing condition, the Cr-containing materials were reduced effectively. The Cr recovery rate up to 97% was obtained while the Cr2O3 content in the end-slag kept below 0.1%. Furthermore, H2 blown through the bottom accelerated the reaction.

系统与集成

Optimization of the Multi-biomass Fuel Ethanol Production System

ZHANG Zhi-qiang HU Shan-ying CHEN Ding-jiang SHEN Jing-zhu DU Feng-guang; LI Peng

. 2013, 13(2):  250-256. 

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This paper takes the system which utilizes wheat, corn, cassava to produce fuel ethanol as the study object, builds up and illustrates a process-based nonlinear programming model for the system with many complex biochemical reactions from some key perspectives such as structure and process parameters optimization, production program selection, etc., which aims at the problems that the constant changes of feedstock cost, product price, subsidy policy and fossil energy market always affect profits. Then, three cases are introduced to make further analysis. The deduction result of the material structure optimization shows that the monthly benefit of the system can be increased by 5%~8% after optimization, and whenever a feedstock price, e.g. wheat price keeps rising, the plant can use other low price feedstock as alternative under the baseline satisfying the process and product quality requirements. The optimized results of product route show that the plant should adjust respective product yield when the prices keep increasing from 0.6 yuan per cubic meter to guarantee maximal. This model is useful for solving the decision-making problems in production, improving the overall efficiency and arranging production for multi-biomass material and multi-product enterprise.

Optimization Methodology of Process System Based on Meta-modeling

LI Qi JI Zhong-li MA Li-min

. 2013, 13(2):  257-263. 

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A general methodology for optimization of complex process system via empirical meta-modeling is described. The uniform design and support vector machine are used to build a meta-model of the system, and the meta-model as fitness function is incorporated into genetic algorithm. This optimization methodology involves data collection from the process simulation model or real operation, and fitting to less complex surrogates: meta-model, which is more readily optimized. The use of empirical meta-model allows the optimization to complex process while requiring only a few of solutions to be obtained from the process model. The effectiveness of proposed optimization methodology of complex process system has been proved by optimizing the operating parameters of Puguang high acid natural gas purification plant. The meta-model of whole process has been built by selecting 10 experimental points within the optimizing space of operating parameters. The relative error of predicted value by the meta-model is less than 4%. The optimization results show that the exergy efficiency of purification plant could be increased by 6.6% under the optimum operating point.

Simulation of Rectisol Process for Purifying the Reformed Gas of Synthetic Oil Tail Gas

ZHANG Yong-jian LI Zhong MENG Fan-hui ZHENG Hua-yan

. 2013, 13(2):  264-269. 

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Based on actual Rectisol process, its simulation for purifying the reformed gas of F-T synthesis tail gas using Aspen Plus software was carried out, some key parameters including flow rate of purified gas and volume fraction of each component were obtained, and the results calculated from Aspen Plus were in consistent with the actual data. The related parameters were optimized using sensitivity analysis method. At last, the capacity of adsorption tower could be improved by 8.84% at the existing operating conditions. The suitable temperature range of methanol was from -44 to -41℃, and the flow rate of methanol to the adsorption tower was decreased by 11.96%, at the same time, the distillation rate of thermal regeneration tower was decreased by 9.55%, when the load of reformed gas was steady and CO2 content in the purified gas was controlled by 0.5%(j), the energy consumption of the purified process was reduced by 9.43% under the optimized conditions.

Application of METSIM in Process Design of Sub-molten Salt Technology for Processing of Vanadium Slag

LV Ye-qing ZHENG Shi-li WANG Shao-na DU Hao WANG Shao-na

. 2013, 13(2):  270-274. 

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The effective cleaner V/Cr production process using sub-molten salt technology has been successfully simulated using METSIM software in order to evaluate the mass balance and energy consumption. Based on the simulation results, the mass and heat balances of each operation unit are obtained, vanadium mainly exists in potassium vanadate crystal, and its mass flow rate is 298.4 t/a, and chromium exists in the potassium chromate crystal, and its mass flow rate is 64.3 t/a, providing valuable reference for the process design. Furthermore, aiming at the problems of high energy consumption and low heat utilization of the process, the optimization of heat exchange network using pinch technology is performed, enabling the reductions of the hot and cool energy consumption by 97.5% and 16.9%, respectively.

生化工程专栏

Preparation of Uniform and Heterogeneous Structure Polystyrene Particles by Premix Membrane Emulsification

ZHU Lin GONG Fang-ling; YUAN Qi-peng MA Guang-hui

. 2013, 13(2):  275-280. 

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Uniform polystyrene (PST) particles with controlled heterogeneous structure were synthesized by premix membrane emulsification method, the effects of the emulsification pressure and cycles, pore size of the membrane used, and porogen on the PST particle size and uniformity were studied. The results indicate that the membrane pore size has linear relation with the average diameter of PST particles and is in inverse proportion to the optimum emulsification pressure. The prepared PST particle sizes can be controlled in 1~6 mm with the size distribution index Span of 0.8, and the relative standard deviation of reproducibility within 3%. Furthermore, the degree of phase separation between polymers and porogen decreases with decreasing of the particle size. Liquid paraffin is unsuitable as the porous medium for the particle size smaller than 2 mm, hexadecane can be used as macroporous medium but with the dosage of under 60% when the particle size is larger than 2 mm.

Effect of Morphology of Aspergillus terreus on Itaconic Acid Production Efficiency

GAO Qian LIU Jie LI Zhen CHEN Jian;

. 2013, 13(2):  281-286. 

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Using Aspergillus terreus to produce itaconic acid (IA), its three morphologies (dispersed mycelia, clump and pellet) were obtained by manipulating inoculum level and flask shape. Then the effects of three morphologies on broth rheology and IA production showed that higher yield of IA on DCW and yield of glucose on DCW were achieved at the clump, than that of dispersed mycelia and pellet. Furthermore, the effect of clump diameter on IA production was investigated by changing KH2PO4 content and culture temperature, which demonstrated that the yield of IA on DCW and yield of glucose on DCW were closely correlated with clump diameter. The optimal clump diameter range for higher yield of IA on DCW was 0.40~0.50 mm, and the yield of IA on DCW and the yield of glucose on DCW were achieved at 4.42 g/g and 8.38 g/g under the conditions of KH2PO4 content 0 and 35℃, which was 35.4% and 27.5% higher than the corresponding values of KH2PO4 content 0.05 g/L and 37℃, respectively.

Application of Poly(glycidyl methacrylate-divinylbenzene-triallylisocyanurate) Monolith in Plasmid Analysis

LIU Meng-ru LIU Lin-lin ZHANG Qi CUI Wei-jia ZHANG Min-lian

. 2013, 13(2):  287-291. 

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Anion-exchange poly(glycidyl methacrylate-divinylbenzene-triallylisocyanurate) (PGDT) monolith with superporous pores with the diameters range of 10~300 mm was synthesized, which was used to analyze plasmid standard and cell lysate. The analysis results were compared with commercial columns, including TSK DNA-NPR and CIM DEAE Disk Monolithic Column. The prepared PGDT monolith could effectively absorb plasmid and separate it from impurities, with its results similar to TSK and CIM

Analysis and Measurement of Total CO2 and Total NH3 in Carbonating Ammoniacal Solution

LIU Ming YANG Peng-bo ZHANG Li-ye; TIAN Yuan CONG Wei

. 2013, 13(2):  292-296. 

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An excessive CaCl2 solution was applied to convert all carbonates and NH2COO- into CaCO3 and NH4+ or (NH3 and NH4+), respectively. Then after CaCO3 was removed by filtrating, the concentration of total NH3 in filter liquor could be obtained by measuring the amount of nitrogen with formol-titration method. And the concentration of total CO2 could be measured by determining the excessive amount of Ca2+ with EDTA titration method. The results showed that relative error of the method for determining the concentrations of total CO2 and total NH3 was less than 1.0% and 1.5%, respectively. Therefore, this method could be adapted to determinate the important index, CO2 loading, when CO2 was absorbed into aqueous ammonia.

Salting-out Extraction of Valuable Components from Waste Liquor of Processing Sea Cucumber

CHEN De-ling YANG Xiang-chun CAO Wen-jing GUO YU-xi SUN Ya-qin XIU Zhi-long

. 2013, 13(2):  297-301. 

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The extraction behavior of protein and polysaccharide in waste liquor of processing sea cucumber was studied in an aqueous two-phase system composed of different hydrophilic organic solvents and inorganic salts. The results showed that t-butanol-(NH4)2SO4 and ethanol-Na2CO3 system performed better in extracting protein and polysaccharide directly from the waste liquor as an interfacial precipitate layer between the upper organic and the lower aqueous phase. The extraction conditions were determined and optimized. For t-butanol-(NH4)2SO4 system, the process was conducted by adding t-butanol (1:1.5, j) and 300 g/L (NH4)2SO4 into the waste liquor of processing sea cucumber at room temperature, resulting in the highest recovery rates for protein and polysaccharide of 99.6% and 96.3%, respectively. For ethanol-Na2CO3 system, the optimum conditions were 16%(w) ethanol, 12%(w) Na2CO3, 72%(w) waste liquor of processing sea cucumber, and the recovery rates for protein and polysaccharide were 96.9% and 90.6% at 37℃, respectively. When the ethanol-Na2CO3 system was progressively enlarged from 30 g to 3 kg, the recovery rates for polysaccharide and protein decreased only by 1% and 0.7%, respectively, meanwhile, heavy metal ions in the waste liquor of processing sea cucumber reduced.

Production of Fumaric Acid from Raw Starchy Materials by Rhizopus oryzae with SSF

GAO Min XU Xiao-kang LI Shuang LI Shuang

. 2013, 13(2):  302-305. 

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To reduce the manufacturing cost of fumaric acid production by fermentation, four kinds of raw starchy materials were investigated, cassava powder, corn powder, degermed corn powder and starch. By comparing the nitrogen contents in them, carbon/nitrogen ratio of raw materials was the key factor affecting the fumaric acid production by Rhizopus oryzae. Based on this point, degermed corn powder was selected as the best raw starchy material for fumaric acid production. In addition, the simultaneous saccharification and fermentation (SSF) process for fumaric acid production was optimized. With degermed corn powder as substrate at 100 g/L total sugar concentration, the fumaric acid production (35.51 g/L), yield (0.355 g/g) and productivity (0.493 [g/(L×h)]) were obtained via SSF process in a 7-L fermentor.

材料工程专栏

Establishment and Application of Supercritical Fluid Extraction and Expansion Apparatus for Preparation of Particles

LI Hai-ting QUAN Can ZHOU Jun-bo

. 2013, 13(2):  306-313. 

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A patented supercritical fluid extraction and expansion (SFEE) apparatus for preparation of particulate products was established, in which supercritical fluid extraction (SFE) with rapid expansion of supercritical solution (RESS) were coupled with. The SFEE technology can directly prepare target nanoparticles from the sample matrix. The demo instrument was controlled by a workstation for automatic control and data analysis. Finally, the applied research using the apparatus was carried out. The mean diameter of stearic acid particles prepared by the apparatus was 0.9 mm, and the contact angle of the paper surface treated by SFEE-AKD was 154o, which meets the requirements of the super hydrophobic properties. So the feasibility of this patent technology and the performance of the demo instrument were verified.

Formation Mechanism of Inclusions in SPCC during CSP Process in JISCO

GUO Jing CHENG Zi-jian CHENG Shu-sen

. 2013, 13(2):  314-320. 

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Steel samples were taken out at the start, intermediate and end of LF refining in the tundish from casting slabs and rolling strips for Steel Plate Cold Commercial (SPCC) during compact strip production (CSP) process in JISCO. SEM-EDS was used to analyze the morphology and composition of inclusions. The results showed that a large number of Al2O3 inclusions with irregular morphology after Al feeding formed, and two routes were found for Al2O3 inclusion modification for SPCC, Al2O3-MgO·Al2O3-CaAlMg multi-component and Al2O3-CA6-CA2-CA-liquid inclusions, and the majority of inclusions could be modified into liquid or solid-liquid coexisting region after calcium treatment. Furthermore, the better the modification of inclusion, the higher the spherical rate and the lower the amount of remaining inclusion in liquid steel. The inclusion composition also significantly affected its size, but the size was determined by other factors. Finally, the formation mechanisms of multi-component inclusions surrounded with calcium-aluminate or CaS ring were analyzed. The former was due to the reduction of Mg in MgO·Al2O3 spinel by Ca or reduction of Al in Al2O3, and the latter was because CaS precipitated directly surrounding solid inclusion core during solidification due to the segregation of S and temperature decreasing. During rolling process, the former had better formative performance, while the outer CaS layer of the latter was easily separated from the inner core and even micro-cracks were caused.

Preparation of Nanoscale Pd-Au@Fe Trimetallic Catalyst Particles for the Dechlorination of Trichloroethylene

TIAN Zhi-hai WANG Yuan YUAN Feng-jun LIU Wei JIN Zhao-hui LI Tie-long

. 2013, 13(2):  321-326. 

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Fe0 nanoparticles were prepared through liquid phase reduction by borohydride in ethanol-water solution, nanoscale Pd-Au@Fe trimetallic catalyst was synthesized by the reduction of Pd2+ and Au3+ with Fe0 nanoparticles. The structure and morphology of synthesized powder were characterized by TEM, EDS and XPS. The Pd-Au@Fe trimetallic catalyst showed the better reductive dechlorination property for trichloroethylene (TCE) than Fe0 monometallic and Pd@Fe bimetallic one. Keeping the dosage of mass ratio of Pd to Fe at constant (0.35%) and Au to Fe at 1.0%, the removal ability of the trimetallic catalyst was the highest. After reaction for 5 min, around 88.21% of 15 mg/L TCE was removed when the catalyst dosage was 1.4 g/L. The dechlorination rate constant was 0.311 min-1, which was 3.6 times of nanoscale Pd@Fe bimetal with the same loading rate. During the degradation reaction process, the generation rate of ethylene and ethane and hydrogenation conversion rate of ethylene to ethane by Pd-Au@Fe trimetallic catalyst are far higher than those by Pd@Fe bimetallic catalyst.

Chemisorption Characteristics of CO and H2 over Iron-based Fischer-Tropsch Synthesis Catalyst

WU Jian-min SUN Qi-wen ZHANG Zong-sen PANG Li-feng LIU Ji-sen

. 2013, 13(2):  327-332. 

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The adsorption behaviors of CO, H2 and syngas over precipitated iron-based Fischer-Tropsch synthesis catalyst were studied by temperature programmed desorption (TPD) and in situ diffuse reflectance FT-IR spectroscopy under the conditions of 25~300℃ and 0.1~2.5 MPa. CO-TPD showed that there were different adsorbed active sites over the iron-based catalyst and linear, twin and bridged CO. H2-TPD evidenced that there were two kinds of desorption peaks (strong and weak) over the catalyst. CO FT-IR demonstrated that clear double linear CO bands existed at 2170 and 2116 cm-1 and a few surface adsorption bands occurred at 1623~1313 cm-1. Characteristic adsorbed CO2 bands appeared with the temperature increasing at 2360 and 2319 cm-1. Meanwhile, the temperature and pressure had effects on CO adsorbed sites over the catalyst. Mechanisms of Fischer-Tropsch synthesis and oxygenate compound formation over the catalyst could be explained by the change of adsorbed species. In addition, increasing the temperature enhanced the CO hydrogenation, while high temperature and pressure favored the formation of C2+-oxygenate compound at the reaction conditions.

Erosion of Refractory by Boron-containing Slag

WANG Shu-huan GUO Jian-long LI Qiu-jing

. 2013, 13(2):  333-338. 

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The experiments were carried out on the erosion of different refractory materials by boron-containing slag with carbon tube and intermediate frequency furnaces in lab. The results with static crucible showed that the average erosion thickness of carborundum, quartz and alundum refractory materials was 0.52, 1.03 and 1.40 mm, respectively. The erosion of alundum was worst, that of quartz at a certain level, and that of carborundum very little. The results with intermediate frequency furnace showed that the erosion of quartz was much bad than that of carborundum. The erosion mechanism of refractory materials by boron-containing slag was analyzed with direct smelting of alloy. Based on phase diagram of slag, the erosion-resistant ability of different types of refractory by slag was analyzed, and the erosion of refractory could be decreased by addition of CaO agent into slag.

Corrosion Resistance of Corundum Spinel Castable to Different Slags

ZHOU Fei-fei JIN Cong-jin CHEN Li-na LI Chong-he ZHEN Qiang

. 2013, 13(2):  339-344. 

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The erosion of corundum spinel castable by high basicity desulfurization and Al-Si killed steel refining slags was studied by dynamic anti-slag experiments with a vacuum induction furnace, and their erosion mechanism analyzed. The results show that the anti-erosion of corundum spinel castable to Al-Si killed steel refining slag is better than that of high basicity desulfurization slag. Because the erosion behavior is mainly affected by the content of CaO and Al2O3 in the slag. The high basicity desulfurization slag contains more CaO, CaF2 and SiO2, which will react with Al2O3 in corundum spinel castable, leading to the serious erosion. Besides, the low content of Al2O3 in high basicity desulfurization slag makes MgO in spinel directly dissolve. The high content of Al2O3 in Al-Si killed steel refining slag will result in formation of spinel at the interface between MgO and slag, leading to indirect dissolving and high resistance to the erosion of slag.

Effects of Width and Inclined Angel of PS Plate on Its Combustion Flame Structure and Spreading

HUANG Xin-jie ZHANG Hao ZHU Qing-ming ZHANG Ying SUN Jin-hua

. 2013, 13(2):  345-350. 

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The flame structure and spread characteristics of insulation materials expandable polystyrene (EPS) and extruded polystyrene (XPS) with the widths (W) of 4, 8, 12 and 16 cm inclined at the angles of 0o, 15o, 30o and 90o in the typical environments of Lhasa (low pressure and oxygen content) and Hefei (normal pressure and oxygen content) were studied. The result shows that the environments affect the flame angle, pool fire length and flame spread speed (vf). For the same width of EPS and XPS inclined at the same angle, the flame angle in Lhasa is bigger than that in Hefei, and it is more influenced by XPS than EPS for the more intensive combustion. The pool fire shows the cyclical increasing and the continual increasing in the length, and has the flowing and dripping characteristics when the width and inclined angle are changed. In Lhasa, the surface flame is easier to extinguish and then the surface zone is ignited again. When EPS and XPS are inclined at the angle of 90o in Lhasa and Hefei, vf firstly decreases with the width of sample and then increases, for the radiative heat flux dominates the whole process. When the width is relatively small, vf follows vfμ1-e-kW, while when the width is large, it follows that vfμTh4.

Preparation of Cellulose Aerogel by the Salt-induced Gelation

WEI Zhi-ping WANG Tao

. 2013, 13(2):  351-355. 

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For the cellulose-7% NaOH-12% urea aqueous solution, adding inorganic salts can induce and accelerate its gelation process. The inorganic salts show a remarkable accelerating effect on the gelation with the sequences as K+>Na+>Li+ for cations and Cl->Br->NO3- for anions. For all kinds of salts used, the gelation rate increases with the increase of the salt dosage. Based on this result, a new preparation method of cellulose aerogels has been proposed using inorganic salt-induced gelation followed by solvent exchange and supercritical CO2 drying. According to the SEM, N2 adsorption and mercury intrusion measurements, the porous structure of cellulose aerogel made through salt-induced gelation is characterized as follows: in the mesopore range, the specific surface area is 284 m2/g, the pore volume 2.0 cm3/g and the average pore diameter 20.5 nm, in the macropore range, the pore volume is 13.95 cm3/g, the average pore diameter 0.732 μm and the porosity 91%.

Preparation and Evaluation of Modified Natural Rosin Oil-soluble Temporary Plugging Agen

ZHAO Qing-bo SHAN Gao-jun

. 2013, 13(2):  356-360. 

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An ideal oil-soluble temporary plugging agent was synthesized from a natural macromolecular rosin, its solubility in diesel, acid resistance, water resistance and dispersivity were evaluated, and the type and concentration of suspension stabilizer determined. In a polymer suspension, the temporary plugging efficiency was more than 93%, and its permeability regeneration rate more than 85%, which demonstrates that the plugging agent meets the demands of selectively breaking down blocks in high water-containing oil-wells in order to increase oil production and control water content.