Effects of concentration and spray pressure on TiH₂ dust ignition and flame propagation

This study examines the ignition and explosive properties of titanium hydride (TiH₂) dust, with the objective of assessing the influence of dust concentration and spray pressure on its explosion and flame propagation behaviour. The minimum ignition temperature (MIT) of TiH₂ dust was ascertained experimentally, and the flame propagation characteristics and velocity were examined. The MIT of TiH₂ dust diminished with increasing concentration, however the influence of powder spraying pressure on MIT exhibited a complex “∧”-shaped trend, attaining its minimum at 0.3 MPa. Experiments on flame propagation indicate that augmenting the powder spraying pressure and dust concentration markedly enhances both the flame propagation height and velocity, particularly at a spraying pressure of 0.5 MPa, when considerable increases in flame propagation speed and height are observed. At 0.5 MPa, the flame propagation reaches a maximum height of 809 mm and a maximum flame propagation speed of 8.04 m/s. The flame propagation speed of 8.04 m/s is the maximum height of the flame propagation at 0.5 MPa. X-ray photoelectron spectroscopy analysis elucidates the chemical state of titanium in the combustion products of titanium hydride, confirming the presence of titanium dioxide (TiO₂) and titanium nitride (TiN) or nitrogen-containing titanium oxides, indicating that nitrogen participates in the combustion reaction and modifies the chemical environment of TiN. These findings are crucial for comprehending and mitigating the explosion danger of TiH₂ dust in industrial applications and offer theoretical support for the secure storage and utilisation of hydrogenated titanium dust.