| During the production of industry, dust explosion accidents always happen and seriously threaten the human life and production safety, causing many casualties, property losses and environmental pollution. Dust ignition is an essential process of dust explosion. It has great significance to prevent the dust from ignition.The main work is as follows:(1) Eight kinds of typical dusts were chosen as the test samples of this investigation. The medium diameters of each dust were as follows. Sulfur:68.85μm; Magnesium-1:275.57μm; Magnesium-2:10.52μm; Aluminum:28.55μm; ABS:88.32μm; Polyethylene:500μm; Corn starch:79.65μm. Their minimum ignition energies were measured in the1.2L Hartmann tube and the minimum ignition temperatures were determined in the Golderberg-Greenwald (G-G) furnace.(2) The influences of reduced oxygen content on minimum ignition energy and minimum ignition temperature were studied.(3) Thermal gravity-Differential Scanning Calorimetry (TG-DSC) tests were carried out. Activation energies and pre-exponential factors of ABS, aluminum, sulfur and polyethylene were calculated. The influences of reduced oxygen content on the curves of TG-DSC were also studied.According to the experiment and analysis, it can be concluded that:(1) The minimum ignition energies and minimum ignition temperatures of each sample are as follows, respectively. Silicone:above10000mJ, above1000℃; Sulfur: below1mJ,225℃; Magnesium-1:3000mJ,650℃; Magnesium-2:3mJ,530℃; Aluminum:1000mJ,720℃; ABS:50mJ,325℃; Polyethylene:above10000mJ, above1000℃; Corn starch:50mJ,425℃.(2) Reduced oxygen content can increase the minimum ignition energy and minimum ignition temperature. The minimum ignition energy of sulfur powder is under1mJ when the oxygen content ranges from13.9%to21%and inerting is not effective in this range. However, the minimum ignition energy of sulfur powder reaches to3000mJ when the oxygen content decreases to10.2%. The minimum ignition energy of magnesium-1doesn’t change with the change of oxygen content, which is3000mJ. The minimum ignition energy of magnesium-2rises from3mJ to3000mJ when oxygen content decreases from21%to10.2%. The minimum ignition energy of aluminum reaches to1000mJ when oxygen content decreases to13.9%. The minimum ignition energies of ABS and corn starch have the same tendencies when the oxygen content decreases, which reach to1000mJ when oxygen content decreases to16.9%.The minimum ignition temperatures of sulfur and corn starch change little when oxygen content decreases, which is in the range of225～250℃and425～450℃, respectively. The minimum ignition temperature of magnesium-1increases from650℃to750℃when oxygen content decreases from21%to10.2%. The minimum ignition temperature of magnesium-2increases from530℃to675℃when oxygen content decreases from21%to10.2%. The minimum ignition temperature of aluminum increases from720℃to1000℃when oxygen content decreases from21%to13.9%. The minimum ignition temperature of ABS increases from325℃to550℃when oxygen content decreases from21%to10.2%.(3) The method of partial inerting can be carried out to prevent sulfur, magnesium, ABS from dust explosion. The recommended maximum oxygen contents are10.2%,13.9%,16.9%, respectively.(4) The activation energies and pre-exponential factors of ABS, aluminum, sulfur and polyethylene were calculated. The list of respective values is as follows. ABS:24.20kJ/mol,0.40s-1; aluminum:465.31kJ/mol,3.90×1016s-1; sulfur:94.04kJ/mol,4.65×106-1; polyethylene:26.03kJ/mol,0.07s-1。(5) Reduced oxygen content can slow down the velocity of oxidizing reaction. It results in that the heat flow of exothermic peak decreases and onset temperature increases when oxygen content decreases. Onset temperature of aluminum has primarily no change while the heat flow of exothermic peak decreases10%when the oxygen content decreases from16.9%to13.9%. |
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