Hydrodynamics of a Liquid-Solid Circulating Fluidized Bed: Effect of Solid Feed Pipe Diameter

An experiment was conducted to acquire a set of systematic data on the solids circulation rate and solids holdup in the riser of liquid-solid circulating fluidized bed (lsCFB) to study the effect of solids feed pipe diameter. In the experiment, five kinds of solids feed pipes with inner diameter 9, 12, 22, 25 and 30 mm were provided. The result indicates that onset transitional liquid velocity, onset solids holdup, average solids holdup and solids circulation increase with increase in solids feed pipe diameter. The results substantiate that the solids feed pipe diameter plays an important role on the hydrodynamics of lsCFB in addition to operating liquid velocities (primary and auxiliary), size and density of solids, solids inventory and liquid viscosity. Based on the experimental data, correlations were proposed for predicting the maximum solids circulation rate, solids circulation rate and solids holdup, which could reproduce almost all experimental data with an accuracy of +/- 8%, +/- 13% and +/- 8%, respectively.