Effect of baffles on bubble behavior in a bubbling fluidized bed for chemical looping processes

Abstract

A bubbling fluidized bed is generally used as the fuel reactor in chemical looping processes. However, insufficient gas–solid contact remains a steadfast problem. As such, we propose the use of internal baffles to split bubbles at a high gas velocity and to restrict the movement of large-scale solids in the fluidized bed. We investigated the effect of baffle arrangement on the bubble size and energy, pressure gradient, particle distribution, and particle velocity in a fluidized bed using a computational particle fluid dynamics simulation based on our experimental results. We discuss the main influencing factors, which include presence of caps, number of baffles, and the baffle opening ratio. The baffle structure with caps efficiently broke the large bubbles without creating jet flow. Three baffles were deemed suitable in the bed owing to the small bubble size and uniform gas–solid distribution in each compartment. We selected a baffle opening ratio of 20.5%, which improved the flow pattern without causing a significant increase in the pressure gradient and particle velocity through the baffles. We also discussed the potential for scaling up this baffled fluidized bed for industrial applications.