Process Equipment Update
rather than the required product weight. The Live Bottom Bin Activator is widely used as it
imparts vibration up through the material mass and allows a controlled discharge which is determined by the size of its internal dome/cone width. The disadvantages are: the units are ideally suited
as a ‘built in’ unit on new silos; in the case of square or rectangular silos, the Bin Activator has to be oversized to take into account the dimensions over the diagonals of the silo; the Bin Activator does not lend itself to being installed retrospectively, as it would involve major and costly structural modification to the silo. The ideal discharge flow
aid device should have:
Fig. 3. Promoflow units are an ideal retro-fit solution where product discharge is problematic.
● A controlled amount of material agitation in the lower regions of the hopper, but not provide agitation in the upper regions. ● Maximum efficiency is achieved by transferring energy into the material, not into the hopper walls. ● It would provide the correct amount of vibration
so as to provide sufficient particle mobility to assure flow, but not cause compaction. It would be quiet in operation. ● The unit would be serviceable externally to the hopper.
● The unit could be retrospectively fitted to any size, shape or configuration of hopper within a few hours.
Expanded metal screen The Promoflow unit consists of an expanded metal screen which is mounted on the inside of the hopper wall. The shaker support frame is rigidly mounted to the metal screen using interconnecting bolts and spacer assemblies. The assemblies pass though the hopper, allowing the shaker to operate external to the hopper. Options exist for water cut stainless steel ‘Rib Cage’ screens for use with larger particle materials. The screen movement is typically 3mm to 4mm which is
sufficient to generate a shearing action. This undercuts the base of any ‘bridging’ formation within the hopper. Because the screens are open to the passage of material,
the hopper walls and not the screen take the majority of material load and allow efficient utilisation of energy. The internally mounted screen would extend from the
outlet up to approximately one third of the length of the sloping wall of the hopper. Various screen shapes and sizes are available to satisfy the requirements of most hoppers. The Promoflow unit is an ideal retro-fit solution where
product discharge is problematic. Its versatility and application flexibility allows it to be fitted to any size, shape or configuration of hopper within a few hours; without any major structural modification and without loss of hopper/silo volume. When used in conjunction with a control timer unit,
product discharge can be adjusted to suit the requirements of the downstream process. This also reduces the air usage and hence the running cost of the unit. ■
Enter 18 or ✔ at
www.engineerlive.com/epe
Gerry Wetton is with Process Components Ltd, Macclesfield, Cheshire, UK.
www.pro-components.com
Fig. 4. Rat-holing is a major problem encountered in storage bins.
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