Safety Evaluation For Dust Combustion & Explosion And MIT Testing Device Development

There are lots of dust explosion accidents in process industry. The statistics about them can declare which kind of dust is more dangerous, and make influential factors clear, and establish the mode of dust explosion and sum up some steps to turn them away or lower the breakage.According to the frequency of accidents and the number of people killed or injured, the following should be controlled firstly: metal, grist, organic substance, complex, fiber, inorganic substance, coal powder etc.In order to understand the risk of dust more exactly, some useful evaluation methods should be built. In this thesis two ways have been introduced. One of them is to analyze the causes of dust explosion by Fault Tree Analysis (FTA), the other is to classify dust risk by fuzzy set.Under special dust circumstance, the two logical operations i.e. the minimum cut set and minimum diametric set are used to analyze the causes of dust explosion, man's influence together with other connotative factors. The conclusion is that more than 10 ways can lead to dust explosion: dust granule, design flaw, dust stack, operation garble, equipment failure, oxidant leaking, shortage of monitor and warning device, knowledge lack, inactive protection lack and inactive gas leakage.For the sake of making dust combustibility clear by microcosm, some parameters should be considered. For example, major grain size, explosion limit, flashing temperature (cloud and layer), minimal combustion energy, maximum blast pressure and its velocity. Base on 7 parameters, different dust's combustibility can be compared to find out their burning similarity under distinguishing confidence by fuzzy mathematics principle. Moreover, likeness degree of dust's combustibility can be accounted for the most dangerous (aluminum powder) in the same way. The weights of 7 parameters can be calculated by Analytic Hierarchy Process (AHP). The outcome precision may be ensured by engineering mathematics method. Theevaluation can provide credible safe explanation for dust using.Dust's combustibility parameters are useful especially when manufacturing, using and depositing. Therefore, some sets of measuring dust combustibility parameters are meaningful. Base on GB & International Electrician Commission (IEC) sketch, Godbert-Greenwald (G-G) oven is improved. Temperature can be controlled more scientifically by describer, and be recorded by computer automatically. In G-G oven, two asbestos boards keep heating energy. There is an alundum tube with an ark between the quartz ampoule and the heater winding. Making hot plate is difficult, but a certain way can achieve this goal. The improved G-G oven is more economical and convenient. Through experiments, MIT of sulfur, wheat, corn and rice etc can be determined on two sets. Compared with the values in literatures, the results are valuable.