It's Just a Feeder !
by Joseph Marinelli
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Dangerous statement. How many bins have you seen with
sledge-hammer marks around the discharge cone? It's easy to under estimate how
important feeder selection is for consistent material flow. You must select a feeder
that not only controls the flow but works well with the flow properties of your bin.
People go to great lengths to develop the proper bin design
based on the flow properties of their material, after the fact!
"The
Fix" usually entails wither retrofitting an existing funnel-flow bin or designing a
new bin to ensure a mass-flow pattern. This fix can be an expensive liner or steeper
hopper angles and as such, you can destroy this effort simply by selecting an
improperly-designed feeder.
Bin and feeder design go hand-in-hand. The feeder
must work in unison with your bin and:
- Suit your materials flow properties
- Work with the bin outlet shape
- Withdraw material uniformly across the outlet's entire
cross-sectional area
- Minimize the vertical loads applied to the feeder
- Accurately control the discharge rate
There are many types of feeders available to suit every
application. You must decide which type is appropriate for a particular application.
Here are several items to consider:
- Volumetric vs. gravimetric feeding.
Do you need
to actually weigh the amount of material discharged or can it discharge by it's volume.
- Feeder Selection. Screw-, belt-, rotary valve-,
vibratory- and louvered-type feeders are all available and have their own advantages and
disadvantages.
- Environmental conditions. Does your feed system
need to be enclosed or dust-tight because of the material is dusty or toxic?
- Feeder effects on material. Is your material
brittle and subject to particle attrition?
There are many other considerations when selecting a
feeder, too numerous to mention here. In future articles I will address more
specific feeder applications.
So put your sledge-hammer away! Remember that the
feeder design is as important as bin design. If your having troubles, ask a
experienced solids flow expert to provide guidance and expertise for your particular bin
and feeder application.
Help others by posting your comments, suggestions and
experiences with bulk solids feeding or any other materials handling concerns you may have
on our On-Line Help Forum. For
past Ask Joe ! Articles, visit the Ask Joe! Archived Articles.
Guest articles for the Ask Joe! Column are always welcome,
for more information please contact Joe Marinelli directly at his email address:
joe@solidshandlingtech.com.
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