Experimental Study On Ignition Of Methane-Air Mixture By Coal Powder In Thermal Environment

Nowadays the methane explosion accidents happened frequently in coal mine in China, and had a great threat to the peaple’s life and property. Spontaneous combustion of coal is generally considered to be an important source of ignition, However, at present there is a lack of experimental study to this field. This thesis has carried out the research about the characteristics of ignition of methane-air mixture by coal powder in thermal environment.According to the needs of the experiment, the author has designed a set of automatic heating device, and applied to the intelligent module to control the temperature; and applied to the Data Transition module to record the change of the coal temperature. The oxidation kinetics parameters apparent activation energy of four different coal samples were tested by the crossing point temperature method. The testing apparent activation energy values of brown coal,1#bituminous coal,2#bituminous coal and anthracite coal were:51.29kJ/mol,57.98kJ/mol,62.61kJ/mol and77.26kJ/mol. Then the author applied to MITL testing device to test MITL of four different coal samples respectively were:270℃,290℃,340℃and>400℃(beyond the testing range). After the experiment we can draw the conclusion that the coal with lower apparent activation energy, the lower MITL and can be ignited more easily.In order to study the characteristics for the ignition of methane-air mixture by coal powder in thermal environment, the author was tested AIT of methane, the result was595℃. Then studied on the influence of existing coal powder with different kinds and diffierent size on the ignition of methane-air mixture in thermal environment below590℃. After the experiment we find that the ignition temperature of methane obviously decrease when there is coal powder exist in thermal environment.When the coal particle’s size is small(0.3mm),1#bituminous coal with high sulfur content can only ignite the methane. After different groups of experience, we can find that the bigger powder of the same coal sample, the lower igniton temperature of methane with coal; the different coal samples of same particle size can ignite methane at different minimum ignition temperatures. the order from low to high is1#bituminous coal,brown coal,2#bituminous coal and anthracite coal. The experimental phenomena and data analysis showed that methane can be ignited by volatile which first get burnt but not the surface burning of fixed carbon.The conclusions of this experimental research have guiding significance for the preventing underground existing from fire and explosion accident where both the coal powder and methane coexist.