Electrical Capacitance Volume Tomography for Characterization of Gas–Solid Slugging Fluidization with Geldart Group D Particles under High Temperatures

Abstract

A three-dimensional ECVT sensing technique is applied to imaging complex slugging phenomena of a gas–solid fluidized bed under ambient and elevated temperature conditions. The study indicates that the time interval between rising slugs decreases with an increase in the gas velocity, reaching a nearly steady time interval value of about 1 s between two slugs when the gas velocity is ∼1.7 m/s above the minimum fluidization velocity. The fluidized bed behaves as a bubbling fluidized bed at low gas velocities. In slugging regime, the slug rise velocity increases with the gas velocity. A mechanistic analysis of forces around the dense phase solid particles suggests that the relationship between the slug rise velocity and the gas velocity for the square-nosed slugging bed is not strictly linear and is highly related to the interparticle forces, internal friction of particles, and gas velocity in addition to the wall stress.