FROM EXPERIMENTS TO CLOSURE EQUATIONS FOR CHAR/ASH DEPOSITION AND SEGREGATION AT WALLS OF SLAGGING ENTRAINED-FLOW GASIFIERS

A critical analysis of impact experiments relevant to entrained-flow slagging gasifiers is hereby presented. The impact-deposition-rebound dynamical patterns of particles colliding with the walls determine the possibility of the establishment of segregated phases which influence the performance of the reactor. A detailed micromechanical analysis of char/ash particles interaction with a surface is considered to characterize ash deposition onto the walls and char particles adhesion and inelastic rebound. The effect of the residual carbon content within the particles from char to ash particles as well as the relevance of the impact velocity has been investigated for different fuels. The experimental outcomes have been used to derive closure equations describing the behavior of char/ash particles after the collision with the wall in terms of deposition and inelastic rebound. It has been highlighted that impact velocity and carbon conversion do influence the deposition tendency of char and ash particles, while the inelastic rebound is mainly influenced by the mechanical properties of the bulk of the particles, which are closely dependent on the structure of particles during the gasification process.