Single-Bubble Dynamics in a Dense Phase Fluidized Sand Bed Biomass Gasification Environment

Abstract

Biomass gasification in fluidized beds is a process of important commercial value. The simulation of these fluidized bed units strongly depends on establishing bubble dynamics in dense phase sand fluidized beds. In these studies, the selected biomass pellet dimensions were 2.7 cm in length and 0.8 cm in diameter. To develop bubble dynamics studies in the present research, a combination of CREC-Optiprobes and a video micro-camera were employed. This was done to record bubble velocity and bubble dimensions in a 200–900 μm particle sand fluidized bed. The effects of biomass pellet concentration on the bubble rise velocity and bubble size and shape were evaluated at conditions close to minimum fluidization. On this basis, a theoretical bubble dynamic model was established. This phenomenologically based model included an adjustable bubble wake parameter, with model predictions providing the bubble chord, bubble frontal ratio, and bubble rising velocity.