微米级锌粉的爆炸危险性

Explosion hazard of micron zinc powders

微米级锌粉易悬浮于空中,形成具有爆炸危险性的粉尘云,粉尘质量浓度一旦达到爆炸下限易发生爆炸事故。爆炸下限随粉尘粒径减小而降低,爆炸可能性增强。为研究微米级锌粉爆炸危险性,选择粒径1μm的锌粉为研究对象,使用20 L爆炸试验装置进行试验,利用扫描电子显微镜观察锌粉及其爆炸产物形貌特征,研究锌粉爆炸机制,点火延迟时间和粉尘质量浓度对锌粉爆炸性参数的影响,确定粒径1μm锌粉爆炸下限、最大爆炸压力和最大爆炸压力上升速率。结果表明:锌粉爆炸为气相燃烧过程;1μm锌粉爆炸的最佳点火延迟时间为180 ms,爆炸下限为1500~2000 g/m^(3),锌粉质量浓度为5000 g/m^(3)时达到最大爆炸压力、最大爆炸压力上升速率和最大爆炸指数,分别为0.481 MPa、46.67 MPa/s、12.67 MPa·m/s;微米级锌粉爆炸危险等级属于St1,爆炸危险性较弱。

The micron zinc powders are easily suspended in the air,forming a dust cloud with explosive risk.An explosion accident will likely occur if the dust mass concentration reaches the lower explosion limit.Also,the lower explosion limit decreases with the decreasing in dust particle size,and the possibility of explosion increases.In order to study the explosion risk of micron zinc powders,size 1μm zinc powders were taken as the research object,the explosion mechanism was studied by observing zinc powders and explosion products while using scanning electron microscope,the influences of ignition delay time and mass concentration on the explosion parameters,and the determinations of the lowest explosion limit,maximum explosion pressure,and maximum rate of pressure rise were done by using 20 L spherical explosion test device.The results show that zinc powders explosion is gas phase combustion process and the optimal ignition delay time is 180 ms.On the condition,the lowest explosion limit is between 1500 g/m^(3)and 2000 g/m^(3).The maximum explosion pressure,the maximum rate of pressure rise,and the maximum explosion index are 0.481 MPa,46.67 MPa/s,and 12.67 MPa·m/s successively when mass concentration is 5000 g/m^(3).The hazard class of micron zinc powders is St1 and the explosive hazard is weak.