Large particles mixed with fine dust are commonly found in the processing and transportation of grain dust. The mixture of dust is exposed to the risk of dust explosions when suspended in the environment. Using a 20 L spherical explosion device and the dust cloud minimum ignition energy (MIE) experimental platform, this study examines the effects of crushed brown rice mixture on the ignition and explosion of fine rice husk dust. The discovery of large granules of crushed brown rice being lifted up to form flow "obstacles" in the mixed dust cloud has a similar inhibitory effect to inert materials, causing the MIE of the dust cloud to increase from 40 mJ to 150 mJ. However, 5 % of crushed brown rice will lower the 10 mJ dust cloud's ignition energy when the concentration of dust clouds is 500 g/m3. Through testing the dispersibility of mixed dust clouds, it was found that fine dust particles adsorbed on the surface of large particles will peel off after being lifted, improving the dispersibility of the mixed dust cloud and forming a system of mixed dust clouds with finer effective particle size, thereby promoting ignition. Furthermore, due to the improvement in the dispersibility of mixed dust clouds by large particles, at mixing ratios below 30 %, large particles will also significantly increase the maximum rate of pressure rise (dP/dt)max, increasing the likelihood of dust ignition and the consequences of an explosion. Therefore, these findings should be taken into consideration during the process of grain processing and transportation.

中文翻译：

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大颗粒混合对细稻壳云点燃爆炸的影响


在粮食粉尘的加工和运输中常发现混有细粉尘的大颗粒。当粉尘混合物悬浮在环境中时，会面临粉尘爆炸的风险。本研究采用 20 L 球形爆炸装置和尘云最小点火能 （MIE） 实验平台，研究了碎糙米混合物对细稻壳粉尘点燃和爆炸的影响。发现大颗粒的碎糙米在混合尘云中被抬起形成流动“障碍”，这与惰性材料具有类似的抑制作用，导致尘云的 MIE 从 40 mJ 增加到 150 mJ。然而，当尘埃云浓度为 500 g/m3 时，5 % 的碎糙米会降低 10 mJ 尘埃云的点火能。通过对混合尘云的分散性测试，发现吸附在大颗粒表面的细尘颗粒在被抬起后会剥落，提高了混合尘云的分散性，形成有效粒径更细的混合尘云系统，从而促进点火。此外，由于大颗粒对混合尘云的分散性提高，在混合比低于 30% 时，大颗粒也会显着增加最大压力上升率 （dP/dt）max，从而增加粉尘点燃的可能性和爆炸的后果。因此，在粮食加工和运输过程中应考虑这些发现。