盘式磨粉机闭路循环中的压力分布研究

介绍了一种盘辊式磨粉机闭路循环系统,对该系统中一些关键部位的压力进行了讨论和研究,指出影响各点压力的主要因素.通过实验测定出这些因素对各点压力的影响情况,并对实验数据进行了详细的分析,得出了一些重要结论,为合理设计和应用这一系统提供了参考依据.     

Enzymatic synthesis of low-calorie structured lipids in a solvent-free system

For the synthesis of low-calorie structured lipids (LCSL), transesterification between triacetin and stearic acid using immobilized lipase in a solvent-free system was investigated. Stearic acid, a long-chain saturated fatty acid, was incorporated mainly into the sn-1 and/or sn-3 positions of triacetin by lipase-catalyzed reaction. Three types of reactor systems (open, closed, and vacuum) were studied for the production of LCSL. The effects of various reaction variables such as water activity of substrates and lipase, molar ratio of substrates, stirring speed and reaction temperature were investigated. In the vacuum reactor system, a certain amount of water was added periodically to maintain the optimal water content of the reaction system. When a suitable amount of water (0.65 wt% of substrates) was added at every 1 h into the vacuum reactor system, more than 88% LCSL was obtained within 4 h using Chirazyme^® L-2.     

相反转法制备超细Bi-Pb-Sn-Cd易熔合金粉

用相反转法将含分散剂的水滴加到熔融的Bi-Pb-Sn-Cd易熔合金液中,制备了一系列超细合金粉,使超细粉的制备与表面修饰同步进行,系统研究了制备过程中温度、搅拌速度和分散剂浓度对超细合金粉粒径的影响。实验结果表明,随着水在合金液中含量的增加,体系发生相转变,合金从连续相逐渐破裂成分散相而形成超细金属粉,同时改性剂以物理吸附的方式对超细金属粉进行表面改性;制备温度、搅拌速度和分散剂浓度对合金粉粒径有明显影响,以浓度为1%的油酸钠为分散剂,温度为85℃,搅拌速度为1750r.min-1,可制得平均粒径为0.3μm的超细Bi-Pb-Sn-Cd合金粉。为获得满意粒径和表面改性效果的超细合金粉,必须将制备温度、搅拌速度和分散剂浓度控制在适当的范围。     

Electrochemical promotion in O<Superscript>2−</Superscript> cells during propane oxidation

The catalytic oxidation of propane was studied in an oxygen ion conducting solid electrolyte cell at 623–773 K and atmospheric total pressure. Three catalyst-electrodes were tested, Pt, Pd and Ag. Under open circuit, the technique of Solid Electrolyte Potentiometry (SEP) was used to monitor the thermodynamic activity of oxygen adsorbed on the catalyst surface during reaction. Under closed circuit, the effect of electrochemical promotion was investigated. On Pt and Pd, the promoting effect was of the “inverted volcano” type. On Pt, the reaction exhibited a strong NEMCA effect; the closed circuit rate exceeded the open circuit rate by more than three orders of magnitude. On Pd, on the other hand, the effect was hardly Faradaic. On Ag, a moderate NEMCA behavior was observed and the promoting effect was purely electrophobic. Both open and closed circuit results obtained with these three catalyst-electrodes, are evaluated and compared to each other.     

不同运行方式对多阳极型微生物燃料电池反硝化及产电性能的影响

利用多阳极型微生物燃料电池（multi-anode microbial fuel cell,MA-MFC）实现生物阴极反硝化过程,分别考察了阴极和多阳极之间不同连接方式、开路或闭路状态、阴极是否存在碳源以及电阻值的大小对MA-MFC的产电性能及反硝化过程的影响。当MA-MFC的阴极存在碳源时,闭路状态下15天内的硝酸盐氮去除率为64.35%,明显高于开路状态下同样时间内的硝酸盐氮去除率（45.89%）。当MA-MFC的阴极不存在碳源时,闭路状态下15天内的硝酸盐氮去除率为17.49%,而开路状态下的硝酸盐氮浓度没有变化。此外,MA-MFC采用并联方式运行时的产电性能和硝酸盐氮去除速率比采用串联方式运行时大幅提高。而在外电阻为100Ω时,MA-MFC在串联或并联状态下均能够达到最高的硝酸盐氮去除率及较高的产电性能。综合上述条件,发现当MA-MFC处于闭路状态、采用并联方式运行、阴极无碳源以及外电阻为100Ω时,能够实现最佳的硝酸盐氮去除率和最大输出功率,分别为94.21%、2.07W/m³。     

Effect of hydrodynamic conditions on the inhibition performance of l-methionine as a “green” inhibitor

Influence of hydrodynamic conditions on the behavior of l-methionine (l-MTI) as a green organic inhibitor was studied using mild steel rotating disc electrode. Electrochemical impedance spectroscopy (EIS) and polarization measurements were carried out in the absence and presence of inhibitor in 1 M H₂SO₄ solution under static conditions and at different rotation speeds; the inhibitor concentration was 5 × 10⁻³ M in all tests. The open circuit potentials (OCP) were measured versus time in all studied rotation speeds; it was found that the OCP shifted toward more positive potentials as the rotation speed increased. It was also found that the inhibition efficiencies for still electrode and low speed rotations did not have noticeable changes, but in much higher rotation speeds, increased efficiencies were observed. This behavior could be attributed to the enhanced mass transport of inhibitor molecules from bulk to the metal surface in high rotation rates.     

一种新型分级机分级效果的研究

介绍了一种新型分级机和由其组成的闭路磨粉系统,指出该系统中影响分级效果的重要因素,并着重对分级机转速和分级叶片处的通流面积两个因素进行了实验研究.结果表明:粉磨方解石时,分级机转速为600 r/min左右、通流面积为0.766 m2时,分级效果较好.     

On the origin of the non-faradaic electrochemical modification of catalytic activity (NEMCA) phenomena. Oxygen isotope exchange on Pt electrode in cell with solid oxide electrolyte

Homomolecular oxygen exchange on Pt electrode in a zirconia electrochemical cell was studied. It was found that the current passing through the cell (O^2– pumping through the electrolyte) does not change the rate of oxygen exchange on the Pt electrode with respect to its open circuit value, a fact that indicates that the strength of the chemisorptive bond of oxygen on the Pt electrode is invariant under open and closed circuit conditions.     

Performance of a Yeast-mediated Biological Fuel Cell

Saccharomyces cerevisiae present in common Baker’s yeast was used in a microbial fuel cell in which glucose was the carbon source. Methylene blue was used as the electronophore in the anode compartment, while potassium ferricyanide and methylene blue were tested as electron acceptors in the cathode compartment. Microbes in a mediator-free environment were used as the control. The experiment was performed in both open and closed circuit configurations under different loads ranging from 100 kΩ to 400Ω. The eukaryotic S. cerevisiae-based fuel cell showed improved performance when methylene blue and ferricyanide were used as electron mediators, rendering a maximum power generation of 146.71±7.7 mW/m³. The fuel cell generated a maximum open circuit voltage of 383.6±1.5 mV and recorded a maximum efficiency of 28±1.8 % under 100 kΩ of external load.     

The effect of chemical composition on portland cement clinker grindability

The relationship between specific power consumption (kWh/t) and Blaine fineness attained during grinding of the Portland clinker is represented by an exponential function. This function varies by stages. For each stage the following equation may be written: In kWh/t = a + bS, where S is the Blaine fineness and a and b are constants assuming different values at each stage. The values of these constants for the first stage, up to about 250 m²/kg Blaine, are not significantly affected by the chemical composition of the clinker, while at the second stage, about 250 – 500 m²/kg Blaine, the values of the constants are affected by C₃A, C₄AF, K₂O and MgO contents.     

Continuous microbial fuel cell using a photoautotrophic cathode and a fermentative anode

A complete microbial fuel cell (MFC) operating under continuous flow conditions and using Chlorella vulgaris at the cathode and Saccharomyces cerevisiae at the anode was investigated for the production of electricity. The MFC was loaded with different resistances to characterise its power capabilities and voltage dynamics. A cell recycle system was also introduced to the cathode to observe the effect of microalgae cell density on steady‐state power production and dynamic voltage profiles. At the maximum microalgae cell density of 2140 mg/L, a maximum power level of 0.6 mW/m² of electrode surface area was achieved. The voltage difference between the cathode and anode decreased as the resistance decreased within the closed circuit, with a maximum open circuit voltage (infinite resistance) of 220 mV. The highest current flow of 1.0 mA/m² of electrode surface area was achieved at an applied resistance of 250 Ω.     

Preparation and Properties of HMX Coated with a Composite of TNT/Energetic Material

To improve the safety of HMX without sacrificing energy properties, the composites of TNT and an energetic material (HP‐1) were used to coat HMX particles by a method of integrating solvent–nonsolvent with aqueous suspension‐melting. SEM (scanning electron microscopy) and XPS (X‐ray photoelectron spectrometry) were employed to characterize the samples. The effect of the processing parameters, such as mass ratio of HP‐1 to TNT (MRHT), stirring speed, and cooling rate, on the quality of coated samples were investigated and discussed. The mechanical sensitivity, thermal sensitivity, thermal decomposition characteristic, and heat of detonation of raw and coated HMX samples were also measured and contrasted. Results show that when MRHT, stirring speed in the second stage and cooling rate are 1 : 5, 1000 r⋅min⁻¹ and 5 °C⋅min⁻¹ respectively, the optimal coating effect is achieved. Compared with that of raw HMX, both impact and friction sensitivity of HMX coated with 2.5 wt.‐% TNT and 0.5 wt.‐% HP‐1 decrease obviously, whereas there is a slight change in their thermal sensitivity and thermal decomposition characteristics. Meanwhile, such surface coating does not result in the decrease of its energy properties.     

两段闭路磨矿工艺在磷酸装置配套湿法磨矿系统中的应用

介绍了两段闭路磨矿工艺技术路线、设备选择以及在云峰分公司磷酸装置配套湿法磨矿系统上的应用效果。应用结果表明,两段闭路磨矿工艺能较好解决开路磨矿存在的磷矿粒度分布呈现粗细两级分化的问题,实现磷酸装置反应工序所要求的-0.15 mm正态分布,提高磷矿转化率和磷收率,最终达到降低磷矿和硫酸消耗的目的。     

A study on the electrocodeposition processes and properties of Ni�CSiC nanocomposite coatings

Ni–SiC nanocomposite coatings were prepared on a brass substrate by electrocodeposition. The electrodeposition was carried out by adding the SiC nanoparticles to a nickel-containing bath. Nickel deposition processes were analyzed by cathodic polarization curves, and the plating parameters were determined preliminarily by analyzing the effects of different technological parameters on the deposition process. Then, electrocodeposition processes were carried out with different concentrations of SiC nanoparticles in the bath. The effects of current density, stirring rate, and SiC nanoparticle’s concentration in the plating bath on the hardness of coatings were investigated by microhardness tests. Besides the microhardness tests, wearing tests and corrosion tests were also applied to the coatings with the highest hardness and coatings of pure nickel. The structures and surface morphologies of the coatings were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The experimental results show that the microhardness of the codeposited coating increases with increasing current density and attains a maximum at the SiC concentration of 6 g/L. The decrease in the microhardness at higher SiC concentrations may be due to agglomeration of nanosized particles in the plating bath. Increasing the stirring speed did not give a better quality deposition as coatings produced at low stirring rates always had higher microhardness values than did those at high stirring rates. Furthermore, the Ni–SiC nanocomposite coatings have lower friction coefficient and better corrosion resistance than those of pure nickel coatings.     

Open circuit potential shifts of activated carbon in aqueous solutions during chemical and adsorption interactions

Interaction of certain inorganic and organic compounds with activated carbon and the effect of such interaction on open circuit potential of activated carbon were studied. Open circuit potential shifts were observed for an overwhelming majority of the substances and brands of activated carbons investigated. Both negative and positive potential shifts were observed. It was shown that open circuit potential shifts for organic substances depend on degree of coverage of the activated carbon surface. Whereas adsorption of investigated organic compound on activated carbon led to positive potential shifts, desorption of adsorbates from the activated carbon surface led to potential shifts in the opposite direction. Furthermore, time dependencies of open circuit potential shifts were similar for different carbon brands. The magnitude of the shifts depended on the adsorbate, adsorption activity of the adsorbent, and the steric configuration of potential-determinative pores and adsorbate molecules.     

Large-area TiO2 nanotube dye-sensitized solar cells using thermal-sprayed Ti layers on stainless steel

This work presents large-scale dye-sensitized solar cells and methods for their manufacture. A dye-sensitized solar cell device contains a photosensitive dye adsorbed on a large surface of the anode, and a transparent conductive cathode disposed opposite the anode, wherein platinum nano-catalytic particles adhere to its surface, and an electrolytic solution is sealed between the anode and the transparent conductive cathode. A titania nanotube film was fabricated by thermo-spraying titanium film on 304 stainless-steel substrate. The photo-current conversion efficiency was tested under an AM 1.5 solar simulator. The dye-sensitized solar cell device has a short current density of 8.22 mA cm^–2, open voltage of 0.71 V, fill factor of 0.59, and conversion efficiency of 3.4%. The internal impedance of the dye-sensitized solar cell was detected and simulated using an electrical impedance spectra technique with inductance, resistance, and capacitance characteristics. The stainless-steel/titania, titania/electrolyte, electrolyte, and electrolyte/(platinum/indium tin oxide) interfaces were simulated using an resistor–capacitor parallel circuit, and bulk materials such as stainless steel, tin doped indium oxide, and conducting wire were simulated by using a series of resistors and inductance.     

工艺条件对陶瓷模具石膏性能的影响

通过对比试验研究了水膏比、搅拌速度、搅拌时间、拌合水温度对模具石膏凝结时间、强度、吸水率性能的影响,并结合SEM、XRD技术探索其影响机理.结果表明:模具石膏成型时合适的工艺条件为水膏比65%~70%,搅拌速度400~500 r/min,搅拌时间2~3 min,拌合水温度25~30 ℃;水膏比、搅拌速度、搅拌时间、拌合水温的变化直接影响了二水石膏的结晶化程度和晶体形态.     

Chitosan nanoparticles with controlled size and zeta potential

Optimization of chitosan nanoparticles (ChNs) production process employing a 2^(5–2) fractional factorial design was performed to analyze the influence of viscosity average molecular weight (40–120 kDa), the initial concentration of chitosan (2–5 g/L), the initial tripolyphosphate (TPP) concentration (0.8–1.2 g/L), the ratio chitosan/TPP (4/1–10/1) (V/V), and the stirring speed (300–700 rpm), on final nanoparticles size and zeta potential. The measured responses of average particle size and surface charge were determined on Zetasizer Nano ZS. ChNs were prepared using ionotropic cross-linking of chitosan and TPP and were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and differential scanning calorimetry (DSC). The experiments showed that the size of synthesized nanoparticles depended on initial concentration and molecular weight of chitosan, TPP concentration and stirring speed within the chosen levels. However, the zeta potential was significantly influenced by chitosan molecular weight, chitosan concentration and stirring speed. The FTIR analysis confirmed the interaction between negative charge of TPP with positive charge of chitosan through the appearance of new peaks at 1222 and 895 cm⁻¹ in produced ChNs. XRD and DSC analysis were used to evaluate the effect of crosslinking of chitosan on crystal structure of ChNs.     

表面羧基化聚丙烯酸酯多孔微球的制备及其铜离子吸附性能研究

以浓乳液作为悬浮聚合的油相,采用水（W）/油（O）/W浓乳液/悬浮聚合方法制备出了内部具有通孔结构、粒径均一的聚甲基丙烯酸叔丁酯多孔微球。结果表明,通过研究乳化剂含量、搅拌速度等参数对多孔微球的内部微孔形貌与微球粒径的影响,发现当乳化剂含量为4 %时,得到的聚合物微球内的微孔结构分布均匀;而聚合物微球的平均粒径会随着搅拌速度的增大而减小。将不同粒径的多孔微球进行酸化水解后得到了表面羧基官能化的聚合物多孔微球,利用其丰富的通孔结构实现了对铜离子（Cu²⁺）的有效吸附,当微球平均粒径介于200~300 μm时,铜离子的去除率最高,可达99.3 %。     

湿球温度与闭式冷却塔蒸发冷却能力关系的研究

以探究环境湿球温度对闭式冷却塔蒸发冷却能力的影响为研究目的,以理论模型闭式冷却塔、实际产品闭式冷却塔以及开式冷却塔为比较对象,给出了不同闭式冷却塔塔型以及同一塔型在不同管材、管径、壁厚等设计细节时环境湿球温度与被冷却水出口温度间的对应关系,并与开式冷却塔作了比较.