On the minimum fluidization velocity in 2D fluidized beds

Abstract

a b s t r a c tIn the present study, a new correlation for the determination of the minimum fluidization velocity in 2D fluidized beds was developed. The proposed correlation was based on the experimental results obtained in 2D fluidized beds with different particle sizes, bed thicknesses and bed heights. Thus, the proposed correlation depends only on the nondimensional variable t/d p , where t is the bed thickness and d p is the particle size. The proposed correlation was compared with other experimental results that can be found in the literature, and two different trends were observed. Namely, one set of experimental results was in accordance with the proposed correlation, while the other set deviated from the theoretical results. In particular, the minimum fluidization velocities of the experimental results were greater than the predicted values of the proposed correlation. In view of the differences in the experimental conditions, the observed discrepancies may be attributed to the effects of electrostatic charge and particle shape. In addition, the experimental fluidization defluidization curves were compared to the theoretical results of Jackson's model, and the parameters were fitted to the experimental data. However, Jackson's model is based on a 1D bed; thus, general parameters could not be obtained for a bed with a fixed particle size and thickness due to the two dimensional voidage distribution in the bed and bed cohesion effects, which are a result of electrostatic forces and are not considered in Jackson's model.

Simulation of object motion in a bubbling fluidized bed using a Monte Carlo method

“…Sánchez Delgado et al (2011) established that U mf increases when decreasing the bed thickness below a certain critical thickness. Above this critical thickness the wall effect is negligible and the behavior is like a 3D bed.…”

Lateral solid mixing in gas-fluidized beds: CFD and DEM studies

“…Hence, we decided to investigate how the choice of bed depth value affects the numerical prediction of In the literature, the effect of the bed thickness has mainly been studied with respect to the minimum fluidization velocity. It was observed that the latter increases as the bed thickness decreases (Caicedo et al, 2002;Kathuria & Saxena, 1987;Sanchez-Delgado et al, 2011;Saxena & Vadivel, 1988). This is because, as the bed depth reduces, the effect of wall friction becomes more pronounced, limiting the movement of the particles.…”

Effect of scraper movement on the separation performance of air dense medium fluidized bed

“…Because of the viscosity of the quasi-liquid (fluidized bed), the moving medium in upper layer would drive the lower layer medium to move in the same directionat a lower speed. Due to the back-mixing of the dense medium powders in ADMFB (Luo et al, 1996;Luo et al, 2008), the merge and breakage of the bubbles are quite complicated in the practical experimental operation (Hernández-Jiménez et al, 2013;Sánchez-Delgado et al, 2011;Zou et al, 2011). As a result, the actual distribution of the bed velocity varies and becomes complicated.…”