Vibratory Discharge Aids

Vibratory discharge aids

Vibratory discharge aids can be attached externally to the shell of a bin/silo as near as practical to the outlet or attached to elements/internals directly in the path of material flow. These devices are used to address flow problems (arching, bridging or ratholing) or incomplete material withdrawal due sticking on hopper walls.

Typical Types

External Vibratory Dischargers

A wide range of vibratory aids is commercially available. Their versatility is partly due to their ease of installation as a retrofit. They may be classified based on the type of energy source (compressed air or electricity) and further on the basis of type of motion generated

Linear vibrators produce vibrations that are perpendicular to the wall of the hopper, act similar to beating the hopper wall with a hammer, whereas rotary vibrators produce components of force both perpendicular and parallel to the hopper wall. Rotary vibrators typically run at higher frequencies and have lower amplitudes than linear vibrators. Twin rotary vibrators mounted in a parallel axis arrangement will tend to run in synchrony and cancel the forces acting in one plane, to produce a linear type oscillating force.

The resulting forces produced by vibratory devices are functions of their mass, amplitude and frequency. Frequencies ranging from 10 Hz to 500 Hz are used, depending on the energy source. Resulting forces are normally limited to 10 g for most applications.

Internal Vibratory Dischargers

Example of this type is the Bin Activators which consists of an inverted cone or baffle suspended across the outlet hopper with supports. There is an annular space between the inverted cone and the outlet hopper through which the material from the bin/silo can flow towards the outlet hopper. The entire assembly oscillates in a horizontal elliptical plane at frequencies ranging from 10 to 50 Hz (typically 30 Hz) and amplitudes ranging from 1/16 to ½ inch. Single or dual exciters can be used to impart vibrations.