Experimental Investigation on Gas‐Solid Behavior in Fluidized Beds with Superfine Particles

Abstract

Fluidized beds are commercially utilized in gas‐solid contacting processes such as the fluid catalytic cracking (FCC) process. Attempts have been made for bubbling fluidized beds to enhance the gas exchange between the bubble phase and the emulsion phase as well as to increase bubble holdup. Low‐density superfine particles 5070S were selected with average diameters of about 10 μm. Unlike agglomerate particulate fluidization of superfine particles on which other researchers have reported, the smaller bubbles, whose diameter is less than 10 mm, uniformly dispersed in the whole bed. Additionally, the gas exchange rate with 5070S became larger than with the FCC particles. Such a unique gas‐solid behavior is probably due to the proper density difference between particle aggregate and fluidizing gas.

Effects of Particle Size Distribution of Low‐Density Particles on Gas‐Solid Behavior in Fluidized Beds

“…For 7040S-R, the Sauter diameters before and under fluidization were 53 and 124 μm, respectively. The fluidized particles are aggregates of primary particles, and the agglomerate size is > 40 μm, similar to that for 5070S reported by Goshima et al [7].…”

“…( 7): The density of fluidized agglomerates with 5070S particle was determined to be 215 kg m -3 from Eqs. ( 3)-( 7) using the mode diameters of primary particle and agglomerate of 5070S, as described by Goshima et al [7], where the density of 5070S agglomerates was estimated as 248 kg m -3 . The density of fluidized agglomerates obtained by the current theoretical model agreed well with that obtained by the Wen-Yu equation using the minimum fluidization velocity.…”

“…Goshima et al investigated the fluidization behavior of superfine particles 5070S, which consists of hollow borosilicate glass microparticles with a mean diameter of 9.98 μm and a particle density of 430 kg m -3 [7]. Although APF occurred at lower superficial gas velocity, unlike the agglomerate particulate fluidization of superfine particles reported by other researchers, the smaller bubbles (diameter less than 10 mm) are uniformly dispersed in the bed.…”

Influence of Surface‐Modified Nanoparticles on the Hydrodynamics of Rising Bubbles

“…Many industrial dispersions, such as emulsions, foams, and suspensions, contain surfactants, proteins, and colloidal particles 1–5. For a long time, the multiphase flow behavior in these systems has been a part of scientific research due to their application in many technological processes for food, pharmacology, or oil recovery 6–8.…”

Characteristics of Geladart-B Particles in Fluidized Beds

“…Muller et al [5] studied the bubble bevavior in two-dimensional fluidized beds using the technology of particle image velocimety. Goshima et al [6] compared the difference of fluidization characteristics between silica nanoparticles and hollow borosilicate glass microparticles and they analyzed the influence of bubbles' sizes from gas exchange rate. Through experiments, Dong et al [7] found that if the decrease of the degree of electrification of granules results in the increase of gas bubble sizes.…”