小麦淀粉粉尘爆炸特性参数的研究

On the characteristic parameters of wheat starch dust explosion

采用哈特曼管式爆炸测试装置和20L球爆炸测试装置对小麦淀粉粉尘爆炸特性参数进行评估,对粒度小于75μm的样品的爆炸危险性参数进行测试,得出了一定条件下的小麦淀粉对静电火花的敏感程度以及其爆炸的猛烈程度,进而对其爆炸危险性程度进行分级。结果表明,温度在25℃,喷粉压力为0.70MPa,小麦淀粉的最小点火能量在40~80mJ;在点火能量为10 kJ时,最大爆炸压力为0.60MPa,最大爆炸指数为7.87MPa.m/s,其粉尘爆炸危险性为Ⅰ级。

In this paper,we attempt to make a systematic assessment of the parameters of explosive characteristics of the wheat starch dust with the Hartmann tube and 20 L sphere explosion test units.As is known,the potential hazards from wheat starch dust explosion have become more and more realistic in the powder processing industrial mills.The disaster of wheat starch dust explosion is characteristic of dust explosion leading to material loss and human casualty,therefore it is necessary to study the key parameters involved so as to make better risk evaluation and then to take necessary measures for technological and human-resource protection.Among the likely disasters to take place are the electric spark discharges when industrially handling the combustible dusts,in which the maximum explosion pressure and the explosion index are two central parameters,which can be obtained from a sample of less than 75 μm.Other parameters,like the sensitivity degree of the wheat starch to the electrostatic spark and the severity degree of explosion under a certain condition can also be obtained from some samples we used and then the likely risk degree of explosion can also be graded.The results of our experiments indicate that the minimum ignition energy of the wheat starch is 40-80 mJ under the temperature of 25 ℃ and powder spraying pressure of 0.70 MPa.With the increase of ignition energy,the wheat starch dust are likely to get burned easily.And,in turn,with the increase of dust concentration,the ignition energy tends to get lowered on the other hand under the dust concentration between 333 g/m3 and 667 g/m3.Furthermore,when the dust explosion pressure and the dust explosion index increase with the dust concentration,the concentration of the dust in the wheat would exceed 500 g/m3.In that situation,the dust explosion pressure and the dust explosion index would become decreased,the maximum explosion pressure is 0.60 MPa and the maximum explosion index is 7.87 MPa·m/s,and in turn the classification of dust explosion hazards would come to be Level I.Thus,it can be seen,that the conclusions drawn from the experimental results are of great significance to the safe application of these combustible substances.