Mass Flow Silos
Mass flow silos are generally for coal or other materials with segregation problems. With the mass flow pattern, the first materials in are the last materials out. This is important with materials like coal, when you need to keep the coal moving within the silo to minimize the risk of spontaneous combustion.
The mass flow pattern allows for the materials to move down the silo as a column with no flow channels. This eliminates stagnant, non-moving materials and/or the effects of segregation of materials stored within the silo. The cone angle will be between 68-72 degrees depending on the material being stored.
Work Principles
Mass flow silos provide first-in, first-out flow with all of the material in motion during discharge. Flow is uniform and reliable; feed density is independent of head of solids in the bin; there are no stagnant regions, so material will not cake or spoil; sifting segregation is minimized; and residence time is uniform, so fine powders deaerate.
Common Design
In mass flow silos every particle is in motion during the discharge; silos are classified as funnel flow silos otherwise.Mass-flow presents some obvious advantages. It guarantees complete discharge of the silo contents at flow rates that are generally predictable. When successfully designed, a mass-flow silo can also re-mix bulk solids which may have segregated during the filling of the silo. Prevention of segregation could be largely addressed by adoption of mass flow. Careful filling procedures are additional or alternative measures when segregation must be avoided.
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