Fluidization Of Group Research Articles

Improvement on flowability and fluidization of Group C particles after nanoparticle modification

Group C particles have gradually become more desirable in the industry in recent years because of their special characteristics such as large specific surface area and small size. However, their poor flowability is the biggest challenge in applications. Nanoparticles, as flow additives, could significantly improve flowability of Group C particles. In this project, powder flowability was measured using three different techniques: FT4 test (cohesion), Avalanche angle (AVA) and Angle of repose (AOR). After nanoparticle modification, Group C particles present much smaller values of cohesion, AVA and AOR, indicating better flowability. In addition, fluidization behaviors such as pressure drop and minimum fluidization velocity were investigated. After nanoparticle modification, Group C particles exhibit good fluidization similar to Group A particles, thus achieving full fluidization with small minimum fluidization velocity.

Fluidization of Group B particles with a rotating distributor

A novel rotating distributor fluidized bed is presented. The distributor is a rotating perforated plate, with 1% open-area ratio. This work evaluates the performance of this new design, considering pressure drop, Δ p, and quality of fluidization. Bed fluidization was easily achieved with the proposed device, improving the solid mixing and the quality of fluidization. In order to examine the effect of the rotational speed of the distributor plate on the hydrodynamic behavior of the bed, minimum fluidization velocity, U mf, and pressure fluctuations were analyzed. Experiments were conducted in the bubbling free regime in a 0.19 m i.d. fluidized bed, operating with Group B particles according to Geldart's classification. The pressure drop across the bed and the standard deviation of pressure fluctuations, σ p, were used to find the minimum fluidization velocity, U mf. A decrease in U mf is observed when the rotational speed increases and a rise in the measured pressure drop was also found. Frequency analysis of pressure fluctuations shows that fluidization can be controlled by the adjustable rotational speed, at several excess gas velocities. Measurements with several initial static bed heights were taken, in order to analyze the influence of the initial bed mass inventory, over the effect of the distributor rotation on the bed hydrodynamics.

Effect of sound on the fluidization of group B particles

AbstractThe behaviour of several kinds of group B particles ranging from 100 μm to 600 μm was studied in a sound wave vibrated fluidized bed (SVFB). The fluidized bed consists of a transparent Plexiglas tube that is 54 mm i.d. × 1 m high. A speaker mounted at the top of the bed was supplied by a function generator with square waves and was used to generate the sound as the source of vibration of the fluidized bed. The influence of the particle size, density of particles and sphericity of particles on the minimum fluidization velocity, pressure fluctuations and bubble rise velocity in the SVFB was investigated. The minimum fluidization velocity decreased as the sound energy increased. When the sound energy was strong enough and greater than the critical power, the minimum fluidization velocity would approach the same value regardless of the degree of resonance (DOR) value if the particles were in spherical shape. For non‐spherical shape particles the minimum fluidization velocity was the function of the DOR value if the power was greater than the critical power. For the middle particle size range, the standard deviation of pressure fluctuations in an SVFB became lower than the one without the effect of sound in high superficial gas velocity range, but the result was reverse for the low superficial velocity; for the large particle size range, the standard deviation of pressure fluctuations in an SVFB was larger than the one without the effect of sound. The sound could also reduce the bubble rise velocity in an SVFB.

Fluidization of group B particles in an acoustic field

The behavior of group B particles (sand with mean diameter 194 μm) was studied in a sound wave vibrated fluidized bed (SVFB). The fluidized bed consists of a transparent Plexiglas tube of i.d. 54 mm and height 1 m. A loudspeaker mounted at the top of the bed was supplied by a function generator with square waves, and was used to generate the sound as the source of vibration of the fluidized bed. The effects of the power of the loudspeaker, sound frequencies, particle loading and the distance between the speaker and the bed surface on the hydrodynamic properties of the SVFB were investigated. The experimental results showed that the minimum fluidization velocity decreased with the addition of acoustic energy, and the standard deviation of pressure fluctuations became lower under the effect of sound. The sound wave also reduced the bubble rise velocity. The results were interpreted in terms of the operating parameters.