The effect of interparticle forces on the stability of gas-fluidized beds - I.Experimental evidence

The stability theory for homogeneous fluidized beds presented earlier is reviewed. This theory is based on the concept of the elasticity of the bed structure as a consequence of interparticle forces. It is shown that this theory explains the effect of gas viscosity and gravity. It is further shown that the elasticity modulus is increased by gas adsorption to the solid surface at elevated pressure and, thus, explains the effect of gas pressure on bed expansion. The theory is compared with experimental results obtained with fluidization of fresh cracking catalyst and polypropylene by different gases and at gas pressures up to 15 bar. It is further shown that the elasticity modulus can be used to correlate bed expansion and bubble size during heterogeneous fluidization. The stability theory of Foscolo and Gibilaro is criticized and rejected on the basis of serious mistakes made in their theoretical derivation.

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