Popcorn ash particles are fragments of sintered coal fly ash masses that resemble popcorn in low apparent density.They can travel with the flow in the furnace and settle on key places such as catalyst surfaces.Computational fluid dynamics ( CFD) models are often used in the design process to prevent the carryover and settling of these particles on catalysts.Particle size,density,and drag coefficient are the most important aerodynamic parameters needed in CFD modeling of particle flow.The objective of this study was to experimentally determine particle size,shape,apparent density,and drag characteristics for popcorn ash particles from a coal-fired power plant.Particle size and shape were characterized by digital photography in three orthogonal directions and by computer image analysis.Particle apparent density was determined by volume and mass measurements.Particle terminal velocities in three directions were measured in water and each particle was also weighed in air and in water.The experimental data were analyzed and models were developed for equivalent sphere and equivalent ellipsoid with apparent density and drag coefficient distributions.The method developed in this study can be used to characterize the aerodynamic properties of popcorn-like particles.
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