Bubbling fluidized bed scaling laws: Evaluation at large scales

Scaling laws for bubbling fluidized beds were first proposed some two decades ago. Although it would appear that the scaling laws for bubbling beds are for the most part successful, generally experimental verification has been limited to small-scale equipment. In this paper we apply the simplified scaling laws to a set of four cold-model bubbling fluidized beds covering a tenfold increase in diameter and perform an experimental verification using an analysis of pressure fluctuations. For pressure fluctuation measurements made at a number of radial and axial locations in all four fluidized beds, an "agreement map" is presented in which the spatial variation in similarity behavior is summarized. Despite a generally good match of results between correctly scaled units, agreement tends to degrade toward the vessel walls and bed surface. At higher gas velocity, pressure fluctuation phenomena observed in the largest bed are not mimicked by smaller units scaled using the simplified criteria. (c) 2005 American Institute of Chemical Engineers.