Characterizing bubble behavior in a pseudo‐2D fluidized bed of wet particles

Abstract

By applying digital image analysis on the bubble characteristics in a two dimensional wet‐particle fluidized‐bed, we report two‐stage evolution of bubble characteristics with increasing liquid content. In the first stage, bubble number and uniformity of bubble fraction increase, while bubble average diameter and aspect ratio decrease. In the second stage, these characteristics shift toward an opposite direction. This two‐stage evolution of bubble characteristics are analogous to that of reducing particle size in dry‐particle fluidization, and the fluidizing properties of particles shifts from Geldart Group B to Group A and then to Group C. Furthermore, liquid addition causes a continuous decrease of bubble fraction and bubble flow rate. This is different from dry‐particle fluidization, in which reducing particle size causes an increase trend. An explanation for this difference is that liquid addition increases the equivalent size of agglomerates in wet‐particle fluidization, which is opposite to the effect of reducing particle size.