Abstract： The sound field model and Eulerian-Eulerian two-fluid model were combined to simulate the effects of sound field on fluidization behaviors of ultrafine powder agglomerates in an acoustic spout-fluid bed with a draft tube. The simulation was performed in the tube with an internal diameter of 120 mm and height of 1 000 mm using the ANSYS Fluent 15.0 of CFD software and the TiO2 ultrafine particles with an average diameter of 290 nm were employed as the solid phase and the air was utilized as the gas phase. The effects of sound field on bubbles and the contours of solid volume fraction, the time-averaged distribution of solid phase concentration, the time-averaged distribution of solid (gas) phase velocity, and the bypass fraction of fluidized gas were studied. The results showed that the acoustic vibration and acoustic turbulence promoted the uniform dispersion of the particles in the annulus and reduced the bubble size, and thus the distribution of solid volume fraction became more uniform. However, due to the higher jet velocity in the tube, the acoustic field had little effect on the solid phase concentration distribution, while due to the decrease of jet velocity near the wall, the solid state concentration decreased. The sound field increased the turbulence intensity in the annular and spouting region, and the axial time-averaged velocity was more evenly distributed in the radial direction. The sound field can effectively inhibit the bypass of the fluidized gas and significantly reduced the bypass fraction of the fluidized gas.
Lei Yuzhuang,Li Hainian,Gu Wei et al. Numerical Simulation of the Fluidization Characteristics in an Acoustic Spout-Fluid Bed with a Draft Tube[J]. 化学反应工程与工艺, 2018, 34(1): 1-10.
