Selection and design criteria
The size and distribution of the design loads depend on the silo structure, the properties of the bulk materials being stored and the flow pattern that is generated during the emptying process. Therefore, for dimensioning and defining the silo geometric characteristics, as well as the opening angle of the discharge hopper at the bottom, we consider
1) the preliminary analysis of
- the physical and mechanical properties of the materials being handled,
- the related filling and discharging method,
- the friction actions on the walls,
- the load pressures on the bottom;
2) the assessment of critical loads, fatigue and combined effects;
3) the estimation of resistance to seismic, wind and snow stresses and actions caused by explosions.
In a mass flow pattern, the complete mass of filling is moving during discharge, therefore the hopper appropriate conicity and discharge section determine the uniform emptying of the silo, with homogeneous lowering of the material level and the exclusion of the formation of solid mass arches during discharge.
Funnel flow (core flow)
With funnel flow, only the material above the opening slides downwards in a channel formed within stagnant material, while the bulk solid at the silo walls remains at rest, resulting in the formation of ratholing, cohesive arches, segregation, product time consolidation, incomplete emptying, erratic or insufficient flow. Material stagnating in a dead zone can be discharged after the silo has emptied out.
Idealtec S.r.l. designs and manufactures metal or fabric vertical silos
- with filling (loading phase) from the top, by gravity, by means of mechanical, aeromechanical, screw and pneumatic conveyors;
- with emptying (discharge phase) from the bottom, by gravity, by means of appropriate extracting systems, designed to prevent cavernous zones and material agglomerations.
- Vibrating bottom
- Aerated bottom
- Plated bottom
- Butterfly valve
- Rotary valve
- Temperature sensors
- Ventilation system
- Powder evacuation system
- Insulation system to prevent the spread of fires/explosions
- Grounding system to prevent the accumulation of electrostatic charges
- Sparks detectors connected to the automatic silo isolation system
- Recirculation fans
- Aeration pipes
- Recirculation pipes