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排序方式: 共有409条查询结果,搜索用时 15 毫秒
1.
International safety regulations such as EN 1127-1 consider ultrasound to be an ignition source. Currently, applications of ultrasound in explosive atmospheres have to comply with a threshold value of 1 mW/mm2. However, it is unclear as to how this intensity has to be measured and, therefore, this threshold value is poorly defined. Moreover, it is based on theoretical estimations in analogy to other ignition sources and there are no publications or significant records on these estimations. Within a research project at PTB, it has now been investigated experimentally in relation to worst-case considerations including airborne ultrasound, focused MHz ultrasound in liquids and acoustic cavitation. On the basis of the results of the research it is now possible to revise the current regulations and to specify measures for safe operation of ultrasonic applications in explosive atmospheres. In this context, for ultrasound coupled directly to gaseous atmospheres a new threshold value of 170 dB (re. 20 μPa) can be suggested, and for ultrasonic applications in liquids, an augmentation can be made to the threshold to 400 mW/mm2. 相似文献
2.
低浓度渣油-水系乳化液的抑尘性能现场试验研究 总被引:2,自引:0,他引:2
本文介绍了作者用渣油-水系乳化液做路面抑尘剂在某矿露天坑3种不同类型路面进行的大规模工业性试验。现场测定结果表明:这种路面抑尘剂可以获得比较理想的防尘效果,长期使用该乳化液可取得显著的综合经济效益。 相似文献
3.
4.
基于TMS320F240 DSP的电网谐波抑制全数字化控制的研究 总被引:1,自引:0,他引:1
为治理电力系统谐波污染 ,提高电力系统运行的安全稳定性 ,笔者对混合式并联有源电力滤波系统的结构和工作原理进行了分析和研究。该系统由无源滤波器和小容量有源滤波器串联构成 ,与被补偿的谐波负载并联连接。基于TMS32 0F2 4 0DSP开发套件 ,设计数字控制器主程序和中断服务子程序。实验结果表明 ,采用TMS32 0F2 4 0DSP编程方便并直观 ,运算精度高 ,控制器参数调整方便 ,易于实现各种控制策略。研究成果对DSP在有源电力滤波系统中的应用有重要参考价值。 相似文献
5.
本文对两种自然爆炸灾害——天体对地球的撞击和空间碎片对航天器的撞击进行了分析,指出了这种自然灾害发生的概率及危害特性,探讨了预防灾害的可能方案。 相似文献
6.
氯气和光气爆燃事故源强估算 总被引:2,自引:2,他引:2
在建立化学品泄漏的气体排放、液体排放、两相排放模式和爆炸燃烧的火球和气爆,蒸气云爆炸及绝热扩散和池蒸发扩展等模式的基础上,估计分析了氯气和光气爆燃事故源强,即爆炸能量及碎片抛射、冲击波、热辐射和毒云等后果影响 相似文献
7.
Threshold values for domino effects caused by blast wave interaction with process equipment 总被引:6,自引:0,他引:6
Valerio Cozzani Ernesto Salzano 《Journal of Loss Prevention in the Process Industries》2004,17(6):437-447
The present study focuses on the definition and assessment of overpressure threshold values for the damage to equipment caused by blast waves originated by primary accidental scenarios. A revision of literature data and of the available damage probability models was carried out. Threshold values were proposed for different categories of process equipment, taking into account either damage levels or release intensities following the loss of containment. Specific threshold values for domino effect were also proposed. 相似文献
8.
极性基湿润剂与矿岩类粉尘颗粒的作用机理 总被引:4,自引:0,他引:4
根据矿岩类粉尘微颗粒的表面性质和极性基湿润剂的特性,应用分子热力学和表面物理化学理论探讨了湿润型抑尘剂与矿岩类粉尘之间的相互作用机理。矿岩类粉尘吸附水的本质是由于它们之间的相互吸引作用,是分子之间的短程相互作用力和长程作用力共同作用的结果。当矿岩类粉尘与水相碰撞时,只有当吸引力大于排斥力时,水分子才能牯附于矿岩类粉尘,表面张力和体系自由能足够小时,水才能湿润矿岩类粉尘。分析了湿润剂对水和矿岩类粉尘的表面改性的原理,它增加水和矿岩类粉尘之间的相互作用力,减小了界面表面张力和体系自由能,使矿岩粉尘被水湿润能自由地进行。 相似文献
9.
Portable Fuel Containers (PFCs) made for consumer use can, under unusual circumstances, develop a flammable atmosphere in the container headspace. In order to prevent an inadvertent ignition from causing flame propagation into this headspace and a subsequent explosion or flame jetting, PFC manufacturers are developing prototype Flame Mitigation Devices (FMDs) for installation in the PFC. A test method is described in this paper to determine if the installed FMD will indeed prevent flame entry into the PFC in a high-challenge flame propagation scenario. The method entails the use of a butane-air mixture ignited in a 5 cm diameter, 12 cm long tube attached to either the container neck or a spout on the container neck. Two concept FMD designs have successfully prevented repeated attempts at flame propagation into the PFC and have also produced encouraging results in tests for fuel flow restriction, duel dispensing nozzle friction, and prolonged fuel exposure. Versions of these tests are currently being promulgated in a draft ASTM standard on PFC FMDs. 相似文献
10.
In this study, in order to research the synergistic inhibition effect of nitrogen and ultrafine water mist on gas explosion in a vented duct, a semi-confined transparent chamber was designed with the size of 120 × 120 × 840 mm, and the experiments were carried out with stoichiometric methane/air premixed mixture (fraction of methane: 9.5%), adding different fractions of nitrogen and ultrafine water mist. The experimental results showed the following: The combination of nitrogen and ultrafine water mist had a synergistic inhibiting effect on methane/air explosion, which was preferable to the single use of any kind. With the increase of spraying time of water mist and fraction of nitrogen, the initial shape of the explosion flame became snakelike, and at the same time the peak flame propagation speed and peak overpressure decreased significantly. When the nitrogen fraction was increased to 10% and the mist spraying time was increased to 2min, synergistic inhibiting effect on overpressure was high efficient. However, with the increase of spraying time of water mist and fraction of nitrogen going on, the amount of increase of explosion inhibition efficiency was gradually reduced. 相似文献