Hydrodynamics and Particle Mixing Characteristics of a Ternary Mixture in a Gas-Solid Fluidized Bed

Abstract

Gas-Solid Fluidized Beds are widely used in current industrial practices for their high efficiency in producing products of very high standards. The study of bed dynamics has become an important concern for the design of fluidized beds. Various parameters like pressure, temperature, gas velocity, mean residence time and solids composition affect the bed behavior. In this view, an experimental study was carried out to determine the influence of gas flow rate, mixing time, solids composition and bed height on mixing/segregation behaviour of the bed of particles. Since fluidized beds involving more than two solids are more frequently encountered in current industrial practices, the experiments were conducted using three solid sand particles of average sizes 231 μm, 335 μm, and 510 μm. Various mixing patterns were observed for different mixing times (10, 20 and 30 minutes), different gas flow rates (7.5, 12.5, 17.5, 22.5 and 27.5 LPM), and different solids ratio. Good mixing occurred at an optimum mixing time of 30 minutes and gas flow rates of 17.5 LPM and 22.5 LPM at all solids ratio. The components exhibited relatively better mixing at intermediate bed heights.