Identification of Clusters in a Circulating Fluidized Bed of Geldart Group B Particles by Multi-Resolution Analysis

In this study, a wavelet –threshold criterion was developed to distinguish the cluster and the void phases from the transient solids holdup/concentration signals measured in a 108 mm i.d. x 5.75 m high circulating fluidized bed (CFB) with glass beads (particle size = 115 micron, density = 2462 kg/m3). An optimal threshold was quantitatively identified by the multi-resolution analysis (MRA) of wavelet transform. In addition, the existence time fraction of clusters, average cluster duration time, cluster frequency and average solids holdup in clusters at different radial and axial positions were determined by the threshold under the fast fluidization flow regime. The results also described the dynamic properties of clusters and flow patterns in the CFBs.