Characterization of temporal and spatial distribution of bed density in vibrated gas-solid fluidized bed

Abstract

This study uses a Φ 200 mm × 900 mm vibrated gas-solid fluidized bed (VGFB) with −0.3 + 0.074 mm magnetite powder was utilized to characterize the temporal and spatial distribution of bed density in VGFB and the influence of bubble movement on fluctuations in bed density. The results indicate that the bed density decreases with an increase in gas velocity (U) and the frequency (f) and amplitude (A) of vibration and that the bed density spatial distribution is lower in the central region but higher in the border regions. The standard deviation of the density first increases then decreases and finally tends to stabilize with an increase in apparent gas velocity. Moreover, when A = 2 mm, f = 25 Hz and U = 14 cm/s, the density distribution is 1.82–1.88 g/cm3 and the fluidization state is improved. The energy of the pressure signal increases with an increase in gas velocity and vibration amplitude. In particular, the low-frequency band of the pressure signal exhibits the highest amplitude and energy, which reveals that bubbles are the main cause of pressure fluctuation. Furthermore, the bed density decreases with an increase in bubble generation frequency, and the relationship between these follows the ExpDec 2 mathematical equation.