Development Of Ignition Device For Coal Dust Cloud And Study On Ignition

The ignition device for coal dust cloud was designed and built in this paper,which prepared for further research of exploring the flame characteristics ofde-mineralized coal on the “Four-High” conditions, laid foundation for "OCCSS"system and the burning and explosion characteristics of combustible gas, combus-tible liquid steam and coal.Firstly, it introduced the design of ignition device for coal dust cloud, se-lected accessories for ignition device and control system.Then, preparation for ignition experiment was introduced, performance testwas made for ignition device for coal dust cloud, the safety and rationality of ig-nition device for coal dust cloud was verified, pressure and vacuum test for thedevice was done to verify its sealing, then, temperature test was made to verify therationality of the temperature system.A preliminary study was done on ignition experiment, coal dust clouds wasnot ignited with the maximum laser power9.3w on any condition, so I made use ofelectric spark to ignite, ignition study of coal dust cloud was done under normaltemperature and pressure, combustion lean limit for different particle size of pul-verized coal was determined, and studied the effect of coal particle size, concen-tration of pulverized coal and ignition energy on the maximum pressure and themaximum rate of pressure rise, the safety and rationality of ignition device for coaldust cloud was verified.The study shows the finer coal particle was, the lower combustion lean limitwas, the maximum pressure and the maximum rate of pressure rise has a big value.When coal particle size was respectively full size,75μm—125μm and8.5μm—12.5μm, combustion lean limit was respectively250g/m3,220g/m3and210g/m3with10kJ ignition energy. When the concentration of coal dust cloud was500g/m3and ignition energy was10kJ, the measured maximum pressure was re-spectively0.65MPa,0.82MPa and0.86MPa, the maximum rate of pressure risewas respectively4MPa/s,12MPa/s and13MPa/s.When the concentration of coal dust was less than700g/m3, the maximumpressure and the maximum rate of pressure rise increased with the concentration ofcoal dust, when it was larger than600g/m3, the maximum pressure0.86MPa nolonger increased with ignition energy10kJ.Maximum pressure rapidly increased with ignition energy, the maximumpressure caused by10kJ was nearly3times than by2kJ. Under the same ignition energy, when the concentration of coal dust cloud was600g/m3, under the maxi-mum pressure was up to0.86MPa with10kJ ignition energy, the maximum pres-sure of600g/m3is larger than200g/m3.200g/m3coal dust cloud reacted weaklycaused by2kJ, which caused a strong reaction for600g/m3, the maximum pressurewas respectively0.12MPa and0.28MPa.