SOLIDS MIXING IN GAS-LIQUID-SOLID FLUIDIZED-BEDS - EXPERIMENTS AND MODELING

Mixing in monosized particles and binary mixtures of solids in three-p hase fluidized beds is investigated by means of a non-invasive Radioac tive Particle Tracking technique (RPT). Pulses of particles at differe nt column heights are constructed from the trajectory of a single radi oactive tracer whose motion is tracked for several hours. For each pul se released, number distributions of particles in the axial direction are thus obtained for each instant of time from injections at differen t axial positions in the reactor. Using this information, axial mixing times for tile solids are measured for the experimental conditions st udied. A one-dimensional two-zone model based on the three-phase count er-current backmixing model used for gas-solid fluidization (Gwyn er a l., 1970) is proposed and solved for these conditions to calculate sol ids axial number distributions and mixing times. Agreement between exp erimental and predicted results is satisfactory.