Two-phase flow behavior in the freeboard of a gas-fluidized bed

An experimental and theoretical study was conducted to identify the flow behavior of gas and particulates in the freeboard of a gas‐fluidized bed. The axial velocity and turbulence intensity distributions were measured along the centerline and across the freeboard. A laser Doppler velocimeter (LDV) was used for the experiments. A technique based on fluorescence emission was developed to discriminate between gas‐phase and particle‐phase velocity information. The gas phase measurements revealed a strong influence of bubble induced turbulence on gas velocity distribution. The axial particle velocity indicated a two‐stage decay with height. Models were developed to predict centerline gas velocity and transport disengagement height.