A STUDY OF THE DISCHARGE OF COHESIVE POWDERS UNDER SIMULTANEOUS AERATION AND VIBRATION

The influence of applying simultaneous aeration and vibration on the d ischarge of cohesive powders from a laboratory scale cylindrical silo has been studied experimentally. The powders investigated were batches of potato starch powder of different moisture contents and therefore different degrees of cohesiveness. The cohesiveness of each powder bat ch is quantified in terms of its unconfined yield strength, which was determined in a triaxial cell. Discharge experiments were performed at different orifice diameters, vibration frequencies, aeration rates an d vibration amplitudes. The results are mainly presented in the form o f contour plots of discharge rate as a function of the aeration rate a nd the vibration intensity. Also the effect of the frequency of the vi bration under conditions of constant vibration intensity is shown. The experimentally determined discharge rates are correlated using publis hed expressions, and discharge coefficients have been determined empir ically.