Experimental study of the interaction of a dense gas–solid fluidized bed with its air-plenum

The influence of the air-plenum on the bed dynamics that can occur for low pressure drop distributors is studied from an experimental point of view and compared with different models from the literature. These experiments are done for a wide range of conditions: A, B and D Geldart particles, different inlet flow velocities and plenum volumes. The effects of the plenum on the bed dynamics are investigated by means of pressure measurements analyzed with an original and accurate time–frequency method, the Hilbert–Huang Transform. The present work clarifies former observations of the literature and specifies the action of the sole plenum, independently of the rest of the air-supply system.

For low pressure drop distributors, changing the dimensionless number θp (which controls the bed–plenum coupling level) induces a strong modification of the bed dynamics associated to a variation of the standard deviation (σ) of the bed pressure drop fluctuations. High values of the standard deviation indicate a strong coupling. There exist a specific plenum configuration that leads to a maximum coupling configuration characterized by a high amplitude motion of the bed with large bubbles that erupt in a very regular way.Figure optionsDownload as PowerPoint slide