Explosion characteristics and suppression evaluation of hydrogen mixed with low-concentration aluminum powder

To ensure the safety of the Al powder/H2 hybrid system in industrial production, the variation law of H2 explosion parameters under the environment of Al powder with a concentration of 0-150 g/m3 was investigated in the confined container, and feasible hybrid explosion suppression approaches were explored. The results show that with the increasing concentration of Al powder, the explosion intensity of the hybrid systems exhibited an enhancing trend in all cases. The explosion hazard of the hybrid system was most severe when the concentration of H2 reached stoichiometry. At 30 % H2 and 150 g/m3 of Al powder, the maximum explosion pressure (Pmax) of the hybrid system was almost 2.4 times compared to the pure 30 % H2 explosion. CO2-driven silica/sodium phytate (SiO2/PA-Na) suppressed explosions more effectively than N2-driven SiO2/PA-Na. As the mass fraction of SiO2/PA-Na was increased to 50 wt%, the CO2-driven solid inhibitors decreased the Pmax and deflagration index (Kst) of the hybrid system by 60.9 % and 90.1 %, respectively, and the delay of the time to peak explosion pressure (Tp) was elevated to 306.4 %. Furthermore, it was revealed that the multi-component inhibitors suppressed the Al powder/H2 hybrid explosion mainly through comprehensive effects such as adsorption of heat, dilution of oxygen, disruption of chain reactions, and isolation reactants. This study contributes to the enrichment of experimental evidence of Al powder/H2 hybrid explosion and the precise development of efficient explosion prevention technology.