Flow structure characterization in conical spouted beds using pressure fluctuation signals

Abstract

Characteristics of the hydrodynamics of conical spouted beds were revealed by analyzing pressure fluctuation signals in the frequency domain. Experiments were carried out in spouted beds with three different cone angles (30°, 45°, 60°) and high density spherical particles (ρp=6050kg/m3) with diameters of 0.5 or 1mm. Different hydrodynamic structures in the movement of solids were identified by examining pressure fluctuations of the bed in the frequency domain. Peaks in the power spectral density of pressure fluctuations were observed corresponding to movement of bulk of solids (low frequency, less than 5Hz), particle transport in the spout (medium frequency, between 5 and 15Hz) and clustering and motion of clusters throughout the bed (high frequency, between 15 and 130Hz). Axial movement of solids and pulsation motion of spout peripheries each exhibits a distinct peak in the medium frequency zone. It was shown by the frequency domain analysis of pressure fluctuations that solids are more mobile in annulus of a bed of smaller diameter particles and there is more effective lateral solid transfer from the annulus to the spout when the cone angle is smaller.