THE EFFECT OF INTERPARTICLE FORCES ON THE STABILITY OF GAS-FLUIDIZED BEDS .2. THEORETICAL DERIVATION OF BED ELASTICITY ON THE BASIS OF VANDERWAALS FORCES BETWEEN POWDER PARTICLES

In Part I of this series it was shown, on the basis of elasticity of the bed structure, that a fluidized powder bed can be stable. It was also suggested that the origin of the elasticity is to be found in the existence of interparticle forces. These interparticle forces are the subject of the present paper. The van der Waals forces between the two neighbouring particles are discussed, while the effect of particle deformation is calculated. Starting from the interparticle forces at the asperities, a model is derived that describes the dependence of the elasticity modulus on the characteristics of the particle bed as, e.g., the bed porosity, the particle diameter and the coordination number.