(104k) Assessing Combustible Dust Hazards of Polydisperse Mixtures in Process Equipment

Many facilities process particulate that is too large in particle size or coarse to be explosible or propagate  combustion when dispersed in air.  However, the bulk material may be polydisperse and contain a fine fraction that can be explosible if segregated from the larger particle size material and entrained in air.  When performing process hazard analyses at facilities, the question often arises, whether there is sufficient fine material that explosible clouds may be produced inside of equipment such as at transfer points or when vessels are filling.  In this paper, we examine the filling of a silo or bin with different particle size mixtures to examine the conditions when sufficient fine material may be suspended in air to create an explosible concentration.  We begin by reviewing previous experiments and simulations that have been performed to analyze the entrainment of fines during the filling of silos.  We then conduct computational fluid dynamic (CFD) simulations to examine the utility of modern CFD codes to analyze the issue.  Guidance is offered on computational and experimental methods that can be used with industrial equipment to determine if an explosible cloud can exsist  when processing polydisperse particulate mixtures.