Small Hopper and Silo Design for Green Coffee

[zleb00]

Hey all,

I'm trying to design a small silo for green coffee for my small business. That 4'-10" is my max. height and I want it to be around 4' wide.

This silo will be square since that will be a little easier for my fabricator to put together.

How important is it that the walls be approx. 60 degrees? Will my material still flow smoothly if I go down to 35 degrees and get a little bit more green in there?

How can I calculate how much it will actually hold once the material inside starts to mound up? I need it to hold at least 500 Lbs.

I looked into a little bit and the dubious results I found are in the corner for my original conception of the silo with a 40 degree angle and rounded sheets on it before I was told I need it to be at least 60 for it flow smoothly and that it would be better for it to be square . Here are those calculations shown a little bit more clearly. Hopefully I am on the right track.


volume of bin = 29000 cu in
volume of hopper = 12000
total volume = 41000
bulk density of green = 0.0278 lbs/in^3
total weight = 1139.8 lbs of green
packing factor of 0.85
TW* PF = 984 lbs

 

[jrmichler]

There is more to hopper design than that. Rather than walk through the design calculations, I suggest the two sites listed below. They do a better job of communicating hopper design than anything I would write.

Good search terms to learn more are dry material hopper design. Those search terms found several good sources, the first of which is https://bulkinside.com/news/ten-steps-to-an-effective-bin-design/. Another good source is https://www.chemengonline.com/hopper-design-principles/?printmode=1.

 

[Baluncore]

I looked into a little bit and the dubious results I found are in the corner for my original conception of the silo with a 40 degree angle and rounded sheets on it before I was told I need it to be at least 60 for it flow smoothly and that it would be better for it to be square .

Many others have been through the design and testing process before you. There are commercial products that you could learn from. Expect a minimum wall slope of 60°, with a 4" opening.

If you are not into maths, or have imperfect data, identify the important factors for your hopper application by asking google something like:
Design of small hopper for green coffee beans?