Ignition energy, explosion flame propagation, and particle movement process of coal dust cloud in vertical Hartmann tube

Abstract

To discuss the ignition energy, explosion flame propagation, and particle movement process of coal dust in vertical glass tube, experimental analysis and numerical simulation methods are used to carry out research. The experimental research results show that the optimal ignition delay time is 1 s, under this condition, the dust cloud near the ignition electrode has the highest turbulence, making it easier to ignite. When the dust cloud mass concentration is 2500 g/m3, the ignition energy is the smallest, resulting in the highest risk of explosion. The simulation results show that the propagation speed of flame is 4 m/s, due to the small amount of suspended dust used, the intensity of the explosion is not significant. The further away from the explosion source, the more energy is lost, the lower the temperature of the flame. Within 30∼50 ms after the ignition, the temperature near the explosion source rapidly increases, from 900 K to 1300 K. During the period of 0.2–0.5 s after dust injection, most particles move upwards along the tube. At 1 s after the dust injection, most particles move downwards and gather near the ignition electrode, forming a suspended dust cloud that is easily ignited, which is consistent with the optimal ignition delay time of 1 s obtained from the experiment.

Keywords

• Dust cloud
• Flame temperature
• Dust concentration
• Ignition energy