Investigation on the correlations between thermal behaviors and explosion severity of aluminum dust/air mixtures

Abstract

Present researches show that aluminum powders with different size show various behaviors. With the increasing of aluminum particle size, reaction rate are greatly reduced and characteristic temperatures are slightly increased, but the melting point of particles seems unaffected by the particle sizes. Surface oxidation of aluminum under lower temperature conditions is controlled by the diffusion resistance of oxygen through the alumina shell. However, under higher temperature conditions, particle burning is mainly controlled by the chemical reaction kinetics. Aluminum dust explosion parameters are positively related to their burning rate. However, the explosion parameters are negatively related to the ignition temperature and maximum burning rate temperature. Aluminum dust with particle size less than 5 μm and dust concentrations among 400 g/m3 to 800 g/m3 would be presenting higher explosion severity. Under lower explosion pressures conditions, γ-Al2O3 was produced. However, α-Al2O3 would be produced only under high explosion pressure condition.