Case Studies in Thermal Engineering (Aug 2024)
Hazard evaluation of ignition sensitivity and explosion severity for aluminum and aluminum powder-petroleum ether mixtures
Abstract
The safety implications of aluminum powder and petroleum ether have garnered significant attention as two typical materials in the production process of energetic materials. To investigate the effect of the common solvent petroleum ether on the ignition and explosion characteristics of aluminum powder, ignition energy, flame propagation characteristics, and explosion pressure of three aluminum powder sizes and their mixtures with petroleum ether through a Hartmann tube test device and a 20 L spherical explosion vessel test system. Findings show that the ignition energy of aluminum powder initially decreases and then increases with the increase of petroleum ether content. At the petroleum ether concentration of 5.5 % and 11 %, the minimum ignition energies of the mixed systems of Al-Flake, Al-T4, and Al-T2 are 1–20 mJ, 5–30 mJ, 450–485 mJ, and 1–20 mJ, 5–25 mJ, 440–480 mJ, respectively. Lower than the minimum ignition energy of the original sample (1–30 mJ, 10–40 mJ, 470–510 mJ), indicating that the aluminum powder dust containing low concentration solvent (5.5%, 11 %) is more sensitive to an electric spark. The ignition energy of the mixed system is rather increased when the content of petroleum ether is further increased to 16.5 %. On the contrary, the probability of ignition and the electric spark sensitivity are decreased. With the addition of petroleum ether to Al-Flake and Al-T4, the flame propagation speed slightly decreases and the phase duration lengthens. The flame propagation characteristics and combustion state of Al-T2 with large particles remained largely unchanged after the addition of petroleum ether. During the 20 L spherical explosion vessel test, the maximum explosion pressure and explosion index of the mixed samples initially increase and then decrease with the increase in petroleum ether concentration. A small quantity of petroleum ether intensifies the reaction intensity of aluminum dust. At an aluminum powder dust concentration of 250 g m-3, the explosion pressure and explosion index of Al-Flake and Al-T4 peak at a petroleum ether content of 5.5 %, while Al-T2 reaches its peak at 11 %.
