CFD-DEM study of spout incoherence phenomena in a conical spouted bed

Spout incoherence widely exists in the application of conical spouted beds and are often taken as a kind of spout instability. However, the hydrodynamics of the spout incoherence behaviour in conical spouted beds has not been well understood yet. In this work, the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) is applied to study the spout incoherence process in a conical spouted bed. A quantification method is proposed to characterize the spout incoherence movement and verified by both the frequency of the flow hydrodynamics and visual observations of particle blockage in the spout channel. With varying operating conditions, two kinds of spout incoherence are observed based on the bubble shape in the spout channel, namely cylindrical spout incoherence and oval spout incoherence, respectively, and the main frequency are 9.2 and 6.8 Hz, respectively. With increasing Usp, the two kinds of incoherence alternatively occur. With the increase of particle loadings, the spout incoherence jumps from the cylindrical spout incoherence to the oval spout incoherence. The results also show that the inclination angle of the conical spouted beds has significant effects on spout incoherence. This work unveils the hydrodynamic properties of the spout incoherence in conical spouted beds.