Research On The Minimum Ignition Energy Of Some Nonmetal Ignitable Dusts

Nonmetal ignitable dust occupies a large proportion of the ignitable dust, they exist in allkinds of industries, most of them are people intensive industries, once the explosion happens,the consequences will be serious. Therefore it has extremely significance to research thecombustion and explosion characteristics of the nonmetal ignitable dust. The minimumignition energy of dust is one of the most important explosion characteristic parameters, itplays a important role in measuring the explosive risk of dust and determining to using whichone of the explosion precautions. The test of minimum ignition energy is affected by manysensitive conditions. So it is very important for preventing nonmetal dust explosion tomeasure the minimum ignition energy of the nonmetal ignitable dust and study theinfluencing factors of the minimum ignition energy.Used the third MIE(minimum ignition energy)measuring device developed by theChilworth company, the minimum ignition energy of two kinds of grain dust(wheat starch andcorn starch)and two kinds of additive dust(soap additive dust and flavor dust)were tested, theeffect of the concentration and environmental humidity to the minimum ignition energy wasstudied, and the ignition mechanism of the dust was analyzed. The results show that:(1) The dust concentration is an extreme factor for the minimum ignition energy of dust,that is to say, there exists an optimum dust concentration, in this concentration the value of theignition energy of dust is minimum. It is measured that the sensitive concentration of wheatstarch and corn starch is about 1200g/m3, and the sensitive concentration of soap additive dustand flavor dust is about 1000g/m3.(2) The influence about the environmental humidity to the minimum ignition energy isobvious. With the increasing of the environmental humidity, the minimum ignition energy ofthe dust increases. To the grain dust, when the environmental humidity is over fifty percent,the minimum ignition energy is more than 500mJ, it can be suggested that the dust isnonflammable. To the additive dust, when the environmental humidity increases fromeighteen percent to fifty three percent, the minimum ignition energy of the dust is one order of magnitude larger. Therefore, in the dust production workshop, it can be used to prevent dustexplosion by increasing the air humidity.(3) It has been tested that the minimum ignition energy of wheat starch and corn starch isrespectively 78.68mJ and 193.5mJ, the minimum ignition energy of soap additive dust andflavor dust is respectively 27.55mJ and 20.33mJ. It can be concluded that the explosive risk ofthe additive dust higher than the grain dust. Besides, according the regulations of theVDI2263, the four dusts are common sensitivity to ignition, the measure of“to avoid theeffective ignition sources”should be used to prevent the explosion.