Hold‐up and axial mixing characteristics of two and three phase fluidized beds

The hydrodynamics of two (water‐air, water‐solids) and three (water‐air‐solids) phase fluidized beds have been studied in a large two‐dimensional column. Two solids were used, namely 6 mm glass beads and 2.6 mm irregular gravel. The individual phase holds‐ups, bed expansion, and axial mixing characteristics were measured. The data were correlated empirically by equations involving liquid and gas phase Reynolds and Froude numbers, and the ratios of the particle and fluid densities. Bubble sizes and rising velocities were determined photographically and found to be of great importance in determining the hydrodynamics of the different beds.