Mechanism of incipient fluidization in fluidized bed at elevated temperature.

Abstract

A new model describing the effect of the adhesive force of particles on the bed structure in a fluidized bed is proposed. Based on this model, equations for estimating the minimumfluidization bed voidage and gas velocity were analytically derived as functions of the particle size and the adhesive force of particles. Froma comparison of theoretical values with experimental values obtained in silica sand beds with various particle sizes at temperatures up to 873 K, the analytical equations were found to give excellent predictions. The predicted values were also found to agree well with the experimental values of bed voidage at ambient conditions by Leva.

Experiments support simulations by the NEPTUNE_CFD code in an Upflow Bubbling Fluidized Bed reactor

“…9 using the average values obtained by imaging and pressure drop measurements. Combining earlier literature findings [47][48][49], Kong et al [1] proposed equations for the slug frequency, f s , the slug length, L s , and the slug intervals, W s . Essential equations are repeated hereafter.…”

Flow patterns in a pilot plant‐scale turbulent fluidized bed reactor: Concurrent application of tracers and fiber optic sensors

“…Studies at more elevated temperatures and relatively low superficial gas velocities were mainly concerned with the effect of temperature on minimum fluidization velocity and bed voidage (Otake et al, 1975; Mii et al, 1973;Sishtla et al, 1986). Reactor size, in most of these studies, was limited to bench scale or laboratory scale units (Kai and Furusaki, 1985;Yamazaki et al, 1986;Cai et al, 1988; Hatate et al, 1988; Rapagna et al, 1994).Modelling of fluidized beds requires the use of data from bubble sensors and tracers. Ege et al (1999, in through a gate valve (V4).…”

Basic theory and experimental approach to characterize flow and fracture properties of fine powder bulk body

“…This electrostatic effect vanished at higher temperature so that the aerated powder gained more fluidity. Similar explanation was also presented by Yamazaki et al (1986). Lettieri et al (2000) showed the effect of temperature on the aeration behavior of FCC catalyst by observing the bed collapse rate and calculated the relative magnitude of the hydrodynamic forces and the interparticle forces as temperature increased.…”

“…It is true that interparticle forces are negligible in aerated coarse particle at ambient temperature, but there have been some researches showing that interparticle forces can be much stronger at elevated temperature, even for the particles which are traditionally recognized as 'coarse particles' (e.g. Kai and Furusaki, 1985, Yamazaki et al, 1986, Kamiya et al, 2002.…”