Transition fluidization in pulsating subcritical water fluidized beds

Abstract

Hydrodynamics of subcritical water (SbW) and particles were simulated using a low density ratio-based kinetic theory of granular flow (KTGF) in pulsed fluidized bed (FB). Five criteria were used to analyze the fluidization state, and results indicated that a transitional state existed in SbW FB, which was characterized by a wavy-like flow near the bottom and large-scale turbulence with chunk-like flow at the upper part. Effects of pulsating inlet fluid velocity frequencies and amplitudes were simulated. The coexistence of the plug-like flow and chunk-like flow occurred along bed height in pulsating SbW FBs. With increasing inlet SbW velocity frequencies, the wavelength increased at first, and then decreased for wave-like flow. The plug-like flow was appeared near the bed bottom with increasing inlet SbW velocity amplitudes. There is an agreement between the measured bed expansion height and computational simulation in an ambient water-particles FB, and the maximum relative error was 1.56 %.