Design and instrumentation of a mid-size test station for measuring static and dynamic pressures in silos under different conditions – Part I: Description

Abstract

Very few experimental installations in the world have full-scale silos, and very few assays have been conducted on them. Consequently, numerous unresolved questions remain which require further research in order to be able to reliably predict the behaviour of the material stored in these kinds of structures.In this article, we describe the design of a full-scale test station for assaying pressure in silos. The installation basically consists of a full-scale, cylindrical silo equipped with load cells to measure pressure and variable-frequency drives connected to each of the electric motors driving the filling and discharge screw conveyors, in order to study the effect on pressure of the speed at which the silo is filled or discharged. As a result of this novel design, it is possible to obtain most of the parameters which control the behaviour of stored material and to compare and validate the different theoretical models used for performing calculations and establishing current standards.The versatility of the silo design also makes it possible to adapt the geometry to the conditions which, in practice, are present most frequently in slender silos, enabling assays to be conducted for flat bottom and hopper silos, and combining both of these conditions with central and eccentric outlets. Furthermore, for each of these configurations it is also possible to study the behaviour of the material under different conditions, including static state, dynamic filling and discharge state, variations in filling and discharge speeds, pressure caused by swelling in the case of material stored when moist or saturated with aqueous solutions, and to perform simulations of an increase in silo height.