Explosion characteristics and combustion mechanism of hydrogen/tungsten dust hybrid mixtures

Abstract

Hybrid mixtures of hydrogen/tungsten dust, which may cause explosions in nuclear fusion reactors and the tungsten industry, have higher risk and more complex mechanism than the explosion of a single combustible medium. The explosion and flame propagation characteristics of hydrogen/tungsten dust hybrid mixtures were studied in a closed combustion tube. The results show that the explosion pressure is dominated by the stoichiometric ratio of the hybrid fuel, while the rate of pressure rise and flame propagation behaviors are mainly dominated by the stoichiometric ratio of the gaseous fuel. The structure and composition of the residues were analyzed. With the change of the hydrogen-tungsten ratio, the composition of the explosion residues can be divided into four regions, corresponding to WO3, WO2.9, WO2.72 and W. Based on the residues analysis, a mechanism for the combustion of a hydrogen/tungsten dust hybrid mixture is further established. The mechanism reveals the combustion mode of tungsten agglomerates in oxygen-rich and hydrogen-rich environments, and explains the effects of heat balance, the mass-consumption rate of oxidizer and the agglomerate radius on the combustion behaviors of the aggregated particles. These results provide a reference for understanding the combustion mechanism of hybrid mixtures containing metal agglomerates and preventing the potential explosion risk.