Distributor performance in a bubbling fluidized bed: Effects of multiple gas inlet jet and bubble generation

Abstract

This work presents a study of the effect of the distributor performance in the bubble generation, growth and interaction within a bubbling fluidized bed. In order to characterize this effect in short-term and long-term dynamics, as well as in time and frequency domain, classical and innovative techniques (Digital Image Analysis, DIA, and Wavelet Analysis WA, respectively) have been used over the images acquired in a two dimensional bubbling fluidized bed.Four perforated plate distributors, with the same open area and the same pressure drop, have been used in the experiments, varying the excess gas and the fixed bed height to study the effect of this operation conditions. The results reveal that the distributor performance has no effect in the mean bubble behavior of the bubbles within the fluidized bed, and therefore there is no effect in the long-term dynamics of the fluidized bed. The analysis, performed on the bubble generation region, also reveals that the distributor as no effect on the bubble generation frequency. However, it can be concluded that distributor performance has a great influence in the bubble generation location along the distributor, being the most homogenously distributed generation profiles, those in which the distributor with the largest numbers of holes and smaller diameter has been used. The distributor affects importantly the total number of bubbles (the higher the number of holes the more bubbles are generated). The fixed bed height does not affect the PDF (Probability Density Function) of the bubbles along the distributor, however the PDF of the bubbles along the distributor presents more homogenous profiles at higher values of the excess gas. These results reveal the great importance of the distributor type in the modelling of bubbling phenomena, but only in the bubble generation region, since from this region the fluidized bed dynamics is not affected for the distributor type.

Emergency shutdown of fluidized bed reaction systems

“…Patil et al (2014) analyzed the transfer through gas bubbles by using a discrete element method. Employing digital image and wavelet coherence analysis, Delgado et al (2019) investigated the distributor performance effect in gas bubble generation, growth, and interaction. Escudero et al (2011) studied the effects of bed height and material density on minimum fluidization velocity and gas hold -up.…”