非真空存储条件对铝粉粉尘爆炸下限浓度的影响

摘要：非真空存储条件对铝粉粉尘爆炸特性有较大的影响。本文选取真空包装的球状铝粉和片状铝粉为研究对象,采用20L球测试装置研究拆封后铝粉放置于干燥器时间的不同对其爆炸下限浓度(Minimumexplosibleconcentration,MEC)的影响。结果表明,刚拆封后球状铝粉和片状铝粉的爆炸下限浓度均为30g/m3。随着存储时间的增加,铝粉逐渐被氧化,两种铝粉的爆炸下限浓度均呈现逐渐增大的趋势。此外,由于球状铝粉的比表面积更大,氧化程度较片状铝粉更为明显,因此存储时间对球状铝粉爆炸下限的影响更为显著,最终铝粉表面生成一层氧化膜,对铝粉的进一步氧化起到一定的保护作用。存储9-12个月,片状铝粉和球状铝粉的爆炸下限浓度分别稳定在50g/m3 和60g/m3。
Abstract： 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/m3. 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/m3 and 60 g/m3 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.