Explosion hazards related to combustible dusts.
Kauffman-CW; Sichel-M; Wolanski-P
NIOSH 1993 Jul; :1-38
Research on the basic elements of a dust explosion, single particle burning, and primary and secondary explosions was presented in a grant final performance report. The physical and chemical processes involved in single particle burning, primary explosions, and secondary explosions were described. Studies focused on the combustion of individual particles, flame propagation in turbulent dust mixtures, and flame acceleration and transition to detonation. A specifically designed furnace for corncob particles was used for studies of individual particle combustion. Heat transfer to the particle was found to be the rate controlling mechanism of the particle burning and ignition processes. The effect of particle size in dust mixtures and the determination of a safe void space were discussed. The effect of turbulence on flame propagation in dust mixtures in primary explosions was examined in a Premixed Turbulent Combustion Bomb. The pressure rise rate was observed to be dependent on turbulence level. A Flame Acceleration Tube was used to study secondary explosions, which are generated by combustible dust layers on the bottom of the tube. Quasi detonations resulting from corn and mira-gel dusts and transition to detonation from wheat and wood dust were observed. Analytical models of dust explosions were developed accounting for the possibility of an explosion of unburned material between the flame and shock precursor. The authors conclude that dust explosions are the result of combustion of individual particles ignited by a primary explosion followed by a secondary explosion caused by the high pressures of an accelerating dust flame.
NIOSH-Grant; Traumatic-injuries; Dust-explosions; Explosive-dusts; Explosive-hazards; Grain-dusts; Wood-dusts; Analytical-methods
University of Michigan, Department of Aerospace Engineering, Ann Arbor, MI 48109-2140
Final Grant Report
National Institute for Occupational Safety and Health
University of Michigan, Department of Aerospace Engineering , Ann Arbor, Michigan