The Shortcomings of Conventional Feeders
The Kamengo Feeder was developed in response to the common shortfalls of conventional feeders. These shortfalls often result in uneven discharge and chronic plugging.
Starting in the late 1970s, Kamengo led a research program to better understand the root causes of bin plugging and found that the feeder was a major culprit contributing to chronic plugging. In particular they found that the conventional feeders have two shortfalls that are particularly problematic when handling a difficult flowing material. These shortfalls include:
Material Compaction. The conveying and shearing action of conventional feeders has a tendency to compact material in the bin. As material is conveyed to a single-point, either through friction or interlocking, the material being sheared from the storage bin carries and conveys material above it. This material is compacted against the front of the bin wall. This compaction injects strength into the material. As the stored material’s shear strength increases, the material is able to bridge over wider distances, making it more prone to uneven feed, bridging and the formation of rat-holes.
Uneven Discharge. Conventional feeders have a tendency to withdraw material preferentially from the rear of the storage bin. This behaviour is problematic for several reasons:
1) for most difficult flowing materials, gravity needs to act on the full span of the discharge outlet in order to be sufficient to keep the material flowing. When the span of the area through which material is flowing is shortened by the behaviour of the feeder, then the material at the outlet requires less shear strength to form a stable bridge or rat-hole. When the shear strength of the material at the outlet exceeds what gravity can break, chronic plugging is expected.
2) uneven discharge promotes a funnel flow discharge pattern, regardless of the geometry of the storage bin. It is particularly unfortunate when a conventional feeder induces a funnel flow discharge pattern in a bin designed for mass flow. This is because most difficult flowing materials will not reliably empty in funnel flow from a storage bin designed for mass flow. To make funnel flow work for a difficult flowing material, it must be discharged from a very long and wide “live” opening.