A novel experimental method for determining lateral mixing of solids in fluidized beds – Quantification of the splash-zone contribution

Abstract An experimental method to investigate the lateral mixing of bulk solids in bubbling fluidized beds is presented. The method utilizes finite volume analysis of the measured temperature field over the bed surface, from which the solids dispersion coefficient is determined. The temperature field is measured with a thermographic camera, which in this work is applied to a fluid-dynamically down-scaled fluidized bed that resembles the conditions relevant for hot large-scale operation. The method is applied to investigate the effect of key parameters for the solids mixing process; fluidization velocity, particle size and pressure drop over the air distributor plate. The results showed up-scaled dispersion coefficients in the order of 10−3 m2/s for the conditions investigated. The lateral mixing of solids decreased with increasing particle size and increased with increases in the fluidization velocity and pressure drop over the air distributor. The method was also used to quantify the contribution of the splash zone to the total lateral solids mixing. When lateral solids mixing in the splash zone was blocked with a vertical baffle the lateral solids dispersion was reduced by some 90%.