(203d) Effect of Particle Morphology on Metal Dust Deflagration Severity and Explosion Protection Design

Combustible dust explosions continue to present a significant threat toward industries processing, storing, or pneumatically conveying metal dust hazards. Through recent years, investigations have thoroughly observed the influence of particle size, polydispersity, and chemical composition on dust explosion sensitivity and severity. However, studies characterizing the effect of particle shape (or morphology) on metal dust explosibility are limited and merit further consideration. In this work, three pure aluminum dust samples of varying particle morphology were examined (spherical granular, irregular granular, and flake). To maintain consistency in results obtained, all granular samples were prepared with similar particle size distribution and dispersity. In the case of flake morphology, particle mass was employed as the control parameter rather than particle size due to the obscure shape relative to granular dust samples. Investigations were performed in a Siwek 20 L sphere combustion test vessel and provide a series of measurements of minimum ignition energy (MIE), maximum rate of pressure rise (∝ K_St), maximum overpressure (P_max), and peak combustion temperature as a function of fuel concentration for all morphologies considered. This work aims to apply scanning electron microscopy (SEM) as a means of correlating specific surface area to dust cloud flame propagation dynamics, with the objective of proposing recommendations to standard risk hazard analysis procedures and to existing metal dust explosion mitigation design guidance.