Impact of Inert Mass Fraction on Explosible Dusts

The dust characteristics, such as ash content (inert mass fraction), energy content, Particle Size Distribution (PSD), and particle density, affect the minimum explosible concentration (MEC) of a dust. The hypothesis is that, at a specific concentration, the combustible particles must be at a certain distance for a flame to propagate from one burning particle to another. The particle distance was determined using Mass Median Diameter (MMD) and particle density, assuming uniform dispersion and all the particles were of the same size. Explosible dusts were mixed with Fuller’s earth, an inert dust, to determine the percentage of inerts required to prevent a deflagration in the Center for Agricultural Air Quality Engineering and Science (CAAQES) chamber. It was assumed that the addition of an inert dust to an explosible dust increases the distance between the combustibles particles, inhibiting the flame propagation. Explosibility tests were also conducted using the CAAQES chamber to demonstrate that the inert mass fraction (ash content) affects the MECs of corn starch and sugar. Additionally, a theoretical approach was developed to determine the percentage of inert dust required to prevent a deflagration based on particle distances. It was concluded that approximately 50% of inert mass fraction will prevent a deflagration, and the high fraction of inerts increases the MEC of a dust by inhibiting the flame propagation. It was concluded that the dust characteristics of CGD rendered it non-explosible.