Study on propagation characteristics of the secondary explosion of coal dust

In the era when renewable energy resources are advocated, traditional fuels still account for a dominant proportion. During coal exploitation, coal dust explosion has been one of the most common and serious disasters. Nevertheless, the generated dust can suspend in the air, further leading to a secondary explosion. However, there are limited studies focusing on the propagation characteristics of secondary explosion induced by coal dust. Therefore, this paper aims to detect coal dust explosion in a pipe network and investigate the secondary explosion caused by the first explosion. In specific, this paper numerically analyzed the propagation characteristics of first and secondary explosion of coal dust in aspects of flame temperature, airflow rate and CO mass concentration. The results indicate that the maximum flame temperature of the secondary explosion of coal dust could reach up to 4500 K, which was more intense than the first explosion. After the secondary explosion, the air velocity witnessed a significant increase, compared with the first explosion, but the air velocity at the linear section of the pipe network witnessed the highest because of the air supplement at two sides. Different from the highest CO concentration at the ignition area in the first explosion, the CO concentration in the secondary explosion source area decreased rapidly and the maximum CO concentration appeared in the flame front. Moreover, because of enough oxygen supplement, the explosion reaction was much more sufficient, so that the maximum CO concentration was less than that in the first explosion.