The limiting aeration condition necessary to produce the collapse of established pipes is evaluated in a powder bed stored in a flat bottomed aerated silo. The main parameters tested are the powders properties and the width of the aeration pad at the silo bottom. The measured quantities are the aeration rate and the corresponding size of the pipe. The gas pressure gradient close to the pipe is estimated from the numerical solution of the air flow field in the bulk solids assuming the Darcy flow regime. The powder permeability necessary for this calculation is estimated by fluidization experiments. The hoop stress evaluated according to Johanson [4] is in good agreement with the unconfined yield strength of the powder provided that the contribution of aeration to powder consolidation during the pipe formation is properly accounted for.

A model on the stability of a pipe in aerated silos

BARLETTA, Diego;POLETTO, Massimo
2014

Abstract

The limiting aeration condition necessary to produce the collapse of established pipes is evaluated in a powder bed stored in a flat bottomed aerated silo. The main parameters tested are the powders properties and the width of the aeration pad at the silo bottom. The measured quantities are the aeration rate and the corresponding size of the pipe. The gas pressure gradient close to the pipe is estimated from the numerical solution of the air flow field in the bulk solids assuming the Darcy flow regime. The powder permeability necessary for this calculation is estimated by fluidization experiments. The hoop stress evaluated according to Johanson [4] is in good agreement with the unconfined yield strength of the powder provided that the contribution of aeration to powder consolidation during the pipe formation is properly accounted for.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/4644556
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