Study of the Deposition Characteristics of Particles on the Slag Wall of a Gasifier

Abstract

In this work, the behavior of coal char particles adhering to the slag wall was studied. The effects of slag thickness and particle size on the restitution coefficient and probability of deposition were mainly discussed. In addition, the types of particle deposition were also classified. The results of exploring the effect of particle size on the coefficient of restitution show that the restitution coefficient of coal char particles hitting the slag wall surface has a complex dimensional effect, with a maximum and minimum coefficient of restitution occurring at the same particle size, a phenomenon referred to in this paper as the discrete effect. The minimum restitution coefficient greater than 0 is regarded as the critical restitution coefficient (εf), and it is considered that particles with theoretical restitution coefficient higher than εf will bounce off the slag wall. With the particle diameter of 600 μm as the boundary, εf first decreases and then increases. The maximum restitution coefficient increases with an increasing particle size of less than 600 μm and stays at a maximum value of 0.62 when the particle size is more than 600 μm. Moreover, the fragmentation of particles occurs at the particle size of 840–1600 μm. The discrete effect was also observed in the experimental data for the investigation of slag thickness, εf increases with the increase of the slag thickness, and the maximum possible restitution coefficient does not change with the thickness of the slag. In addition, according to the statistics of the deposition probability, it is found that the smaller the particle size, the greater the deposition probability, the thicker the slag thickness, and the easier it is to deposit.