FUNCTIONAL DESIGN OF SILOS, BINS, and HOPPERS

When faced with the functional design of silos, bins, or hoppers to handle your bulk solids, you can be confident that Jenike & Johanson engineers have the knowledge and experience to assist you. A vessel that has been “functionally” engineered means that it has been designed per the flow characteristics of the bulk material to be handled and the requirements for the application (e.g., flow rate, layout).

Our functional designs for silos, bins, and hoppers include:

• General configuration – overall geometry with critical dimensions
• Hopper shape, angle, internal surface – critical for mass flow silo
• Outlet size and shape – designed to prevent bridging and meet flow rate
• Storage capacity – based on specific bulk density and angle of repose
  
• Feeder interfacing

Selection of the silo, bin, or hopper discharge pattern is critical in the functional design phase. Review flow pattern features below.

After completion of a vessel’s functional design, Jenike & Johanson engineers can perform loading analyses and structural/detailed design. These engineering tasks are vital steps for achieving successful project completion.

Mass flow

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.

Example mass flow silos

Funnel flow

Many vessels discharge bulk solids in a funnel flow pattern, where some of the material moves while the rest remains stationary. Funnel flow discharge is acceptable if the bulk solid is coarse, free-flowing, not prone to cake, and if segregation is not important.

Example funnel flow silos

Expanded flow

Expanded flow, which is a "hybrid" flow pattern, develops when a mass flow silo hopper is placed below a funnel flow hopper. The mass flow hopper is designed to activate a flow channel in the funnel flow hopper, which is sized to prevent the formation of a stable rathole. The major advantage of an expanded flow over mass flow is headroom savings.

Example expanded flow silo