Flame propagation behaviors and influential factors of TiH2 dust explosions at a constant pressure

The flame propagation through TiH2 dust cloud at near constant pressure condition is studied in a series of experiments using an apparatus with transparent latex balloons. The influential factors for the combustion performance of TiH2 dust cloud, including dust concentration, particle size, scale of isobaric space and oxygen content are investigated. Results show that the burning velocity increases with dust concentration in the fuel-lean mixtures, and then plateaus after crossing the stoichiometric condition, while the trend of flame speed changing with dust concentration varies for different mean particle sizes (D50) of 48 and 106 μm. The flame propagation speed of dust cloud is positively correlated to the isobaric space scale and oxygen content. The burning mechanism of TiH2 dust is thought to be mainly controlled by diffusion regime, the appearance of hydrogen gas accelerates the combustion rate of TiH2 particles and also makes the TiH2 dust changed from a discrete media to a continuum, which may account for the phenomenon that the flame speed in dust cloud of TiH2 is larger than that of Ti at the same concentration no matter in air or oxygen atmosphere.