Fire & Explosion Protection Laboratory, Northeastern University, Shenyang 110819, China.
J Hazard Mater. 2013 Feb 15;246-247:283-90. doi: 10.1016/j.jhazmat.2012.12.038. Epub 2012 Dec 28.
The minimum temperature at which dust layers or deposits ignite is considered to be very important in industries where smoldering fires could occur. Experiments were conducted on the self-ignition behavior of magnesium powder layers. The estimated effective thermal conductivity k for modeling is 0.17 W m(-1)K(-1). The minimum ignition temperature (MIT) of magnesium powder layers for four different particle sizes: 6, 47, 104 and 173 μm, are also determined in these experiments. A model was developed describing temperature distribution and its change over time while considering the melting and boiling of magnesium powder. Parameter analysis shown that increasing particle size from 6 to 173 μm increased MIT from 710 to 760 K, and increased thickness of the dust layer led to a decreased MIT. The calculation termination time more than 5000 s didn't significantly impact MIT. Comparing predicted and experimental data showed satisfactory agreement for MIT of magnesium powder layers at various particle sizes. According to the ignition process of magnesium powder layer, a meaningful definition for the most sensitive ignition position (MSIP) was proposed and should be taken into consideration when preventing smoldering fires induced by hot plates.
在可能发生闷燃火灾的工业中，灰尘层或沉积物点燃的最低温度被认为非常重要。对镁粉层的自点火行为进行了实验。用于建模的估计有效热导率 k 为 0.17 W m(-1)K(-1)。还在这些实验中确定了四种不同粒径（6、47、104 和 173 μm）的镁粉层的最小点火温度（MIT）。开发了一个模型，描述了在考虑镁粉的熔化和沸腾的情况下，温度分布及其随时间的变化。参数分析表明，从 6 到 173 μm 增加颗粒尺寸会将 MIT 从 710 增加到 760 K，并且增加灰尘层的厚度会导致 MIT 降低。计算终止时间超过 5000 s 不会对 MIT 产生显著影响。比较预测和实验数据表明，对于各种粒径的镁粉层的 MIT，预测值与实验值吻合良好。根据镁粉层的点火过程，提出了一个有意义的最敏感点火位置（MSIP）定义，在防止热板引起的闷燃火灾时应考虑该定义。
