Experimental and numerical analysis of jet penetration and gas evolution in a single-nozzle distributor fluidized bed

This paper studies the injection of gas in a stagnant solid bed via a horizontal nozzle from experimental and theoretical perspectives, with the analysis of permanent jet plumes and subsequent bubble detachment. Advanced 3D X-Ray imaging techniques have been developed and used to observe the phenomenon, as well as to quantify important process parameters (gas distribution, jet length, bubble size, etc.). The experimental results are compared with those obtained from three-dimensional computational fluid dynamics (CFD) simulations of a gas-solid fluidized bed with primary air injection performed through a two-orifice horizontal nozzle. The proposed model correctly predicts the jet penetration at all the jet velocities tested. Uneven distribution of air through the cross-section of the bed is also observed, with the presence of the same two distinct regions experimentally observed, namely a fluidized core region and a compacted peripheral region. However, the model fails in predicting jets interaction and curvature due to asynchronous bubble detachment from the jets. This study demonstrates the usefulness of X-ray radiography in noninvasively visualising detailed internal features of industrial fluidized beds, thus providing an excellent benchmark to challenge the assumptions made in computational and theoretical models.