Abstract：The signals of particle concentration and pressure fluctuation in the annulus were measured using an optical fiber probe and a pressure sensor respectively in an acoustic spout-fluidized bed with a draft tube. A half-cylinder was used as the fluidization column, instead of ultrafine powder agglomerates, hollow microbeads with an average diameter of 150 μm were employed as raw materials while the high-speed atmosphere jet was utilized as the spouting gas. The effect of acoustic field on fluidization quality in the annulus was investigated by analyzing both traditional statistical analysis and power spectrum analysis. The results showed that the low-frequency and high-intensity sound wave could effectively break bubbles in the upper region of the annulus, reduce the size of bubbles, increase the concentration of particles in the bubble. The two-phase structure of the bed was weakened, the mean concentration of particles was increased, and the concentration fluctuation was reduced. The higher the sound pressure level, the more obvious the effect. However, there was an optimal value for the frequency of the sound wave, which was 70 Hz under this experimental condition. Higher or lower than this value, the effect of acoustic field was weakened. Meanwhile, the sound wave could eliminate the channeling in the bottom of the annulus, promote the uniform distribution of the fluidizing gas. The particle concentration was reduced, the concentration fluctuation was increased, and gradually approached the upper region with the increase of sound pressure level. Thus, the axial fluidization state in annular region became more uniform and the fluidization quality was improved.
GUO Ting,HE Chuan,LI Hainian et al. Effect of an Acoustic Field on Fluidization Quality in the Annulus of a Spout-fluidized Bed with a Draft Tube [J]. 化学反应工程与工艺, 2019, 35(6): 501-508.
