Description
Flat bottom silos need ot be unloaded – and there are a few ways to achieve this – being
a) Horizontal augers
b) Horizontal chain conveyors
c) Horizontal chain conveyors
d) Horizontal belt conveyors
e) Inclined augers
By far the most popular option is with horizontal augers – as horizontal augers have (comparatively) low power consumption, comparatively low grain breakage and low cost of operation and maintenance
The auger is installed in a channel in the silo foundation (for channel aeration, or no-aeration flat bottom silos) or on top of the foundation, but under the full aeration floor (for full aeration silos), and is typically installed with a single centre well, where most of the grain is unloaded from, and then depending on the diameter of the silo, a number of intermediate wells (between 1 & 4 usually)
The wells are controlled from the outside of the silo, usually with a rack and pinion wheel, which pulls a shaft or pipe, connected to the well slide, to open and close the wells. It is enormously important when unloading silos, that the centre well should always be opened first, until the grain no longer flows through the well, due to the natural angle of repose of the grain. Only when the centre well can no longer discharge grain (thus the centre well should be visible when looking down at the grain in the silo from the roof hatch), should the intermediate wells be opened to discharge some of the other grain, so that the sweep auger can be started, and the door of the silo be opened.
It is important to space the last intermediate well, closest to the silo door, at a spacing, which will allow the grain to unload from the silo on the door side, sufficiently so that the door of the silo can open.
Wells can be controlled either manually, or electrically – but as standard manual wells are usually offered.
Well sizes are determined by the auger installed, to ensure that the maximum flow of grain is achieved into the well, without blocking the conveyor. Intermediate wells will usually be smaller than the centre well, as all intermediate wells are opened simultaneously – to prevent overfeeding of the conveyor.
Unload augers are available as standard in 219mm or 273mm tube diameters – with capacities ranging between 40 and 75TPH. For larger unload capacities, other silo unload opotions should be considered.
