液氢生产中若干固氧爆炸事故分析及防爆方法概述

对一些氢液化器在液氢生产中发生过的固氧爆炸事故作了分析， 试图通过这些事故， 总结经验， 从中探索出防止发生固氧爆炸事故的途径与方法。

液氢生产中若干固氧爆炸事故分析及防爆方法简述

对一些氢液化器在液氢生产中发生过的固氧爆炸事故作了分析，试图通过这些事故，总结经验，从中探索出防止发生固氧爆炸事故的途径与方法。文内简述了各种防瀑途径，根据固氧爆炸的特点和我们的研究成果，提出了三种防爆方法，以期防止这类爆炸事故的发生。

党参对鼠J774巨噬细胞吞噬活性的增强效应

验证党参对机体免疫功能的增强效应并探索其作用机理。方法 :用党参水提液加入鼠 J774巨噬细胞培养液中作微量细胞培养 ,以自动微量荧光分析仪直接检测其对细胞吞噬活性的影响。结果 :显示党参水提液对巨噬细胞的吞噬活性有明显的增强作用 ,在浓度 5 0 0～ 3 0 0 0 μg/m l时 ,与无药对照组 ( O)比较都有显著性差异 ( P<0 .0 5 ) ,分别增强 1.3 3～ 1.70倍。结论 :巨噬细胞是重要的免疫活性细胞之一 ,对机体免疫反应的各个环节都起关键性作用 ,党参能增强机体免疫的效应 ,可能是通过其增强巨噬细胞的免疫活性而实现的。

Explosive limits of mixed gases containing CH_4,CO and C_2H_4 in the goaf area

The explosive gases CO and C2H4, released mainly flammable gases during the process of coal self-ignition, are of the most important ingredients of the multi-component gases in goal areas, along with CH4. We have determined some of the parame- ters of explosive properties of the one-component gases CH4, CO and C2H4 using an explosive trial device of polybasic explosive gas mixtures and emphasized particularly the effect on the limits of explosive concentration of the binary explosive mixed gases CH4＋CO, CH4＋C2H4, as a function of the amount of CO, C2H4 and inert flame resisting gases （N2, CO2）. The experimental results show that the effect of inert gases on the explosive limits of mixed gases, given the property of explosive gas, is obvious： the inert gases （N2, CO2） possess some inhibitory effects on the explosion of the multi-component explosive gas mixtures. The results will provide some experimental support to suppress the occurrence of the gas explosions in goaf areas and provide some directions for designing explosion-proof electric equipment and fire arresters.

Effect of non-vacuum storage condition on minimum explosible concentration of aluminum dust

Non-vacuum storage condition has a great impact on the explosion characteristics of aluminum powders. In this paper, vacuum-packed flake and globular aluminum powders stored in a dryer after opening the vacuum package are selected as the experimental samples, and a 20 L spherical explosion device is chosen to test the minimum explosible concentration (MEC) values of aluminum dusts under different storage time. The results show that the MEC values of two types of unoxidized aluminum powders are 30 g/m^3. The MEC values of flake and globular aluminum powders firstly go up with the increase of storage time in the dryer and then reach the maximum values of 50 g/m^3 and 60 g/m^3 at respective storage time until finally they stabilize gradually. The main reason is that the oxidation rate is faster owing to the bigger specific surface area of globular aluminum powders. Hence, the storage time has more significant effect on the MEC of globular aluminum powder than that of flake aluminum powder. After a period of time, the outer surface is oxidized to generate a layer of film, which prevents the further oxidation of aluminum powder, resulting in the temporary stability of MEC.

Thermotics Study of the Semimetallic Nylon1010 Composite

Thermal expansion characteristics of semimetal nylon composites (nylon 1010 incorporated with metal oxides) were analyzed with thermal expansion instrument. The changes of composite weight after being heated and the heat absorption and release of the composites were analyzed by carrying out TG-DSC experiments. Experimental results show that the average thermal expansion coefficient of the composites rises as the average diameter of the metal oxides decrease from room temperature to 160 ℃. Thermal dynamics and physical properties of the nylon composites change with the addition of the oxides; the crystallization temperature rises from 180 ℃ of pure nylon to 190 ℃ (maximum) and the melting point of the oxide composites also increases continuously with the addition of the oxides. The water content of the oxide/nylon composite is related to the kind and content of the oxide. The water content reaches its maximum when the content of oxide is 10%, and the 10% Al2O3/nylon composite has a water absorption ratio up to 1%.

Impact of an accidental explosion in Tianjin Port on enhanced atmospheric nitrogen deposition over the Bohai Sea inferred from aerosol nitrate dual isotopes

In recent years,emergent pollutant’s accidents have occurred frequently in China,causing serious harm to the ecological environment.In this study,the impact of an accidental fire and explosion at Tianjin Port in 2015 on the atmosphere over the Bohai Sea was explored.Results showed sharp increases in the concentrations of several important components of fine particulate matter(e.g.NO3−,SO42−,NH4+,organic carbon,elemental carbon)over Beihuangcheng Island after the explosion.Among them,NO3−was most affected(about 10 days),with a maximum concentration of 16.45μg m−3.Theδ15N-NO3−ranged from−1.58‰to+8.74‰,with an average of+2.79‰±3.32‰.Influenced by the explosion,δ15N-NO3−decreased significantly,which was in accordance with the industrial processes of explosives.Theδ18O-NO3−varied between+49.40‰and+69.52‰,and showed a marked increase(+66.62‰±3.92‰)in the explosion-affected period.Using Monte Carlo simulation,the•OH pathway for NO3−formation was 51.79%±10.94%at that time—much lower than in the regular period.The elevated dry deposition of NO3−caused by the explosion was 266.08μmol N m−2 d−1 over the Bohai Sea—again,much higher than in the regular period.With the dry nitrogen deposition of NH4+(42.41μmol N m−2 d−1),the total nitrogen deposition increased by 308.49μmol N m−2 d−1,leading to severe ecological risk.Through the inverse computation of the dry deposition flux of NO3−,the affected area over the Bohai Sea was less than 1.42×104 km2,which is about 20%of the total area.

Synthesis of PE with Broad MWD Catalyzed by Supported Ziegler-Natta Catalyst Consisting of Cycloalkoxy Silane as IED

Two kinds of cycloalkoxy silane compounds were synthesized and used as the internal electron donors （IEDs） of supported Ziegler-Natta catalyst for ethylene polymerization to produce polyethylene with broader molecular weight distribution （MWD）, The effect of the structure and the amount of these IEDs on the polymerization performance was in- vestigated. The results implied that the molecular weight distribution of the obtained polyethylene could be adjusted by the incorporation of IEDs. SEM result showed that the morphology of catalyst particle was spherical and uniform in size distribution. The titanium content of these catalysts was higher, the active TiCl4 species were easily anchored on the support than that without adding IED, which was determined by ICE The GPC result confirmed that the polyethylene with broader molecular weight distribution in the range of from 23.4 to 25.6 was obtained using triethoxy-（-cyclopentyloxy）-silane （ED1） and triethoxy-（-cyclohexyloxyl）- silane （ED2） as the internal electron donors.

Mechanical alloying of platinum with 5% ZrO_2 nanoparticles for glass making tools

Synthesis and characterization of mechanically alloyed Pt-5%ZrO2(volume fraction) for structural components in the glass industry were described. Zirconia(ZrO2) nanoparticles(<100 nm) were produced by the electrical explosion of zirconium(Zr) wires, and blended with platinum(Pt) powders(<44 ?m) for 2-72 h in ambient atmosphere. The Pt particle size followed the typical decreasing trend of the normal ball milling process up to 48 h, but particle agglomeration was observed at 72 h. The grain size evolution was similar to that of the particle size, dropping down to around 50 nm at 48 h. The root mean square strain of the Pt crystallites showed the opposite behavior, maximizing at 48 h with a subsequent relaxation process. For the 48 h ball milled powders, spark plasma sintering was carried out to form a bulk disk. The measured mass loss of the sintered bulk sample shows a decent thermal stability despite its relatively low density.

Flammability and Explosion Property of Gases in the One-Step Process of Propane Oxidation to Acrylic Acid

Abstract： In order to study the flammability and explosion property of gases during the propane oxidation to acrylic acid process, the explosion limits and the safety oxygen content of gases at the recycle gas compressor outlet, the reactor inlet, and the reactor outlet were theoretically calculated and experimentally tested. Finally, the inert limit was also determined. It showed that gases at the recycle gas compressor outlet and the reactor outlet were nonflammable based on three indicators： the explosion limits, the safety oxygen content and the inert limit. The C3H6 and O2 contents were higher at the reactor inlet, which made the mixed gases easily ignitable. However, the large amount of inert gases suppressed the possibility of explo- sion effectively. As a consequence, no explosion phenomenon would happen in all three locations. But gases at the reactor inlet are most dangerous, where more supervision on the concentration of gases and more strict control on the temperature and pressure should be implemented. Besides this, open flame, hot surfaces and other sources of ignition are prohibited in working spaces. The experimental results can be applied to similar process for oxidation of propane.

Laser-induced Alignment and Coulomb Explosion of CO2

Dynamic processes of CO2 are experimentally studied in intense femtosecond laser fields with laser intensity varying from 1×10^13 W/cm^2 to 6×10^14 W/cm^2. When the laser intensity is below the ionization threshold, a coherent rotational wave-packet is formed for CO2 at room temperature through nonadiabatic rotational excitation. The evolution of the wave-packet leads to transient alignment. The field-free alignment revives periodically after the laser pulse is over. The revival structure can be modified by a second laser pulse for the rotational wave-packet through precisely adjusting the time delays between the two laser pulses. When the laser intensity excesses the ionization threshold, ionization and Coulomb explosion occur. The atomic ions C^m＋ （re=1-3） and On＋ （n=1-3） observed in the experiment exhibit highly anisotropic angular distributions relative to the laser polarization. Using two linearly polarized laser pulses with crossed polarization, we conclude that the anisotropic angular distribution results from dynamic alignment, in which the rising edge of the laser pulse aligns the neutral CO2 along the laser polarization direction prior to ionization.

Effects of different product phases in aluminum dust detonation modeling

Modeling aluminum(Al)dust detonation is difficult due to uncertainties in the product species and fractions.Recent experiments indicate both gaseous and solid alumina may appear in the detonation product,but only the gaseous one was considered before.To resolve this drawback,we study the effects of different product phases on the detonation parameters with the hybrid combustion model proposed recently.Numerical results demonstrate that the assumption of gaseous product induces high velocity and pressure,while the assumption of solid product induces low velocity and pressure.To clarify how close-to-experiment results have been obtained with one phase assumption,we revisit previous studies and analyze the models.The inconsistency between the product phase and heat release is found,and then one model with variable heat release dependent on the product phase is proposed.Then simulations with both the gaseous and solid products are carried out,and results reveal the necessity of establishing a relationship between the heat release and reaction products.