Effect of dust dispersion on particle integrity and explosion hazards

Dust explosion hazards can be described with parameters such as MIE, MEC, P-max, K-st etc., which are known to depend on particle size distribution within a dust cloud. Literature has shown the dispersion system (outlet valve, in particular) in a standard 20-L dust explosion apparatus breaks the dust into smaller particles leading to explosion parameters not necessarily corresponding to the original size. This study uses a novel dispersion system in a 36-L dust explosion apparatus to eliminate the mechanical shearing from the outlet valve and investigates its effect on dust particle integrity. The study also aims to observe the role of dispersion stages (nozzle and dispersion cloud turbulence) on particle breakage and compare the performance of our dispersion system to that of a standard 20-L apparatus. In addition, the role of dust dispersion concentration on particle breakage is examined. Anthraquinone, Acetaminophen (Paracetamol) and Ascorbic Acid are used to accomplish the goals of the study. Finally, the effect of dispersion on a nanomaterial is investigated using Carbon Nanofibers (CNFs). Anthraquinone, Acetaminophen and Ascorbic Acid show that even in the absence of an outlet valve, significant particle breakage occurs. This demonstrates the major role of both the dispersion nozzle and cloud turbulence in particle breakage. In addition, the experiments revealed dispersion concentration to be an important factor in particle breakage and helped establish the inverse relation between particle breakage and dust dispersion concentration. Nanomaterial experiments with CNF5 show significant de agglomeration in the dispersion cloud followed by re-agglomeration. (C) 2016 Elsevier Ltd. All rights reserved.