Effects of soft-sphere model parameters in the simulation of slagging gasifiers

The correct prediction of the interaction of char and ash particles with confining walls in an entrained-flow slagging gasifier calls for a proper assessment of the parameters governing the dynamics of impacts between particles consisting of partially or fully converted coal and a surface partially covered by a viscous layer of molten ash. The limiting conditions of these interactions are: unconverted rigid and non-sticky coal particles versus fully converted plastic and sticky ash particles, on one side, and rigid bare non-sticky walls versus sticky walls covered by a flowing layer of molten ashes, on the other. A DEM simulation model has been used to explore how the presence of multiple particles in the near-wall region of the gasifier affects the effective deposition rates of char and ash onto the confining walls, hence the rate of rebound. The formation of a dense layer of particles in proximity of the walls’ surface is critically affected by particle–wall interaction. This study is focused on the effects of selected simulation parameters on the dynamical patterns of particle impact under the four limiting regimes, and on the choice of parameters that more closely represent particle–wall interaction under realistic process conditions.