Sensitivity analysis of dust explosion of organic/mineral mixtures

Roberts, Joshua

Student Work

Sensitivity analysis of dust explosion of organic/mineral mixtures

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The objective of this research project is to study how the dust explosion of Niacin is affected by several factors and how different inerts inhibit the explosion of Niacin when mixed together and suspended in air. This is important because the number of explosions in the animal feed industry went from 8.6 to 20.2 explosions per year from 1900 to 1988 (Eckhoff, 2003). Since 2016, there has been an average of 29.3 explosions per year, resulting in 183 injuries and 15 deaths (Keefe & Cloney, 2023). The industry is massive, with over 250,000 employees (IFIF, 2020) and an annual turnover rate of more than $400 billion (IFIF, 2024). Anything that can burn in air can become explosive if subdivided enough, with the rate of its reaction increasing exponentially until it becomes an explosion, which can be triggered by a number of sources. A 20-L sphere was used to test Niacin and mixtures of it with inerts to see how its explosion is affected by concentration, turbulence, and the location of the chemical igniters within the sphere. Also, the decomposition of NaHCO3 was explored, determining how its endothermic, radical scavenging decomposition affects Niacin’s explosion. The in-situ PSD of powder injected into the sphere was measured using a modified 20-L sphere and a Sympatec HELOS/KR-Vario laser. NaHCO3 and NaCl greatly inhibit the explosion of Niacin because they are radical scavengers with endothermic decompositions, which remove heat and H+ and OH- radicals from the reaction. MgO and CaCO3 did not inhibit the explosion as well, because they are not radical scavengers and only act as heat sinks for the reaction. Decomposing NaHCO3 into Na2CO3 increases the explosion severity greatly, but less so when CO2 is added to the sphere before the explosion. Moving the chemical igniters from the center of the sphere reduces the explosion severity because the flame gets quenched by the cold walls of the sphere. Increasing the ignition delay time linearly decreased the explosion severity exponentially. The dust particles became heavily fragmented when injected into the sphere because of the high force exerted on the particles.

This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

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