Discharge of Packed Magnetizable Particles through Side Orifice in the Absence and Presence of a Magnetic Field

Abstract

The magnetizable and active particles in the magnetically stabilized bed (MSB) should be regenerated in time to ensure the continuous treatment of the influent gas. We proposed solving this problem by integrating the MSB with the dual-dense gas–solid circulating fluidization technique. In this case, laws governing the discharge of magnetizable particles from the MSB through the side opening should be mastered. The discharging behavior of packed iron particles through the side orifice was first explored. The mass discharge rate (q) was constant over time and increased as the orifice size or particle size increased. The angle of repose (β) at the end of the discharge decreased with increasing orifice size or particle size. Smaller particles usually had greater inherent interparticle forces and poorer flowability. After the axial uniform and steady magnetic field was exerted, q decreased, whereas β increased as the field intensity (H) increased. Both variations became steeper at higher values of H. The magnetic field induced additional interparticle forces and decreased the flowability of the magnetizable particles. After H exceeded a certain value, the packed iron particles were magnetically frozen and ceased to flow out of the orifice. Under the action of the magnetic field, the discharge of packed magnetizable particles through the side orifice could also be predicted by the well-known Beverloo equation; the effect of H could be well-reflected by k embedded therein. k was demonstrated to be more comprehensive than various repose angles in characterizing the flowability of packed particles through orifices.