Particle-wall impact experiments for entrained-flow biomass gasifiers

Particle–wall interaction phenomena relevant to entrained-flow biomass gasifiers have been investigated. The dynamics of char and ash particles as they are impacted onto a flat surface in hot conditions has been characterized by means of high speed imaging and tracking. Two types of biomass have been investigated, i.e. wood chips and corn stover. Particle–wall collisions were described in terms of normal, tangential and global coefficients of restitution. The influence of carbon conversion and impact velocity on the dynamical pattern of rebound and deposition has been investigated. The results indicate that the global restitution coefficient for char and ash particles is well below 1, suggesting that some plastic deformation occurs upon impacts. Furthermore, ash of wood chips is not prone to form a slag layer, while ash of corn stover extensively contributes to formation of ash deposits and melts. The dissipation of momentum associated with particle impact promotes the establishment of a dense-dispersed phase in the near-wall zone of entrained-flow slagging gasifiers.