Visualization of Particle Behavior near the Wall of a CFB

The particle behavior near the wall of a circulating fluidized bed has a significant effect on the heat transfer characteristics and material erosion in the fluidized bed. Visualization of the particle behavior proves useful in understanding the hydrodynamics involved. In this study we used photography to study the particle behavior near the wall for two configurations. In one case, the model wall was in an inclined position and the particle behavior of a falling thin film of particles was observed. In the other case, the vertical wall of a circulating fluidized bed at atmospheric pressure was observed. Both experimental cases were conducted with and without an obstacle step on the wall. It was found that the individual particles forming a flow stream had a random behavior. With a thin step at the wall a serious disruption of the flow over the step and downstream of the step is produced.