Blockage of constrictions by particles in fluid–solid transport

Blockage is an important phenomenon in particulate flow. Work was undertaken to provide a better understanding of key hydrodynamic multiphase flow factors which cause, or contribute to, stalling and blockage in particulate feeding systems such as those used for feeding biomass into reactors. Rubber and plastic particles were hydraulically conveyed along a horizontal rectangular duct leading to constrictions of different geometries. Experimental results showed that large size, irregular shape, high volumetric concentrations of particles, small constriction dimensions and particle compressibility all increased the likelihood of blockage. Reynolds number also had a significant effect on particle behaviour and blockage propensity. The pressure drop needed to break a blockage is also considered, based on a simple horizontal packed bed model.