Glossary of Terms

Many terms are unique to the field of powder and bulk solids storage, handling, and processing.  Definitions of common terminology follow.

[popover image=”/your-need/poor-flow/hopper-flow-obstruction-arching-bridging/” link_text=”Arching” title=” ” content=”A costly no-flow problem” direction=”right”]

A no-flow condition in which material forms a stable arch (bridge) across the bin

Attrition

The generation of fines or dust during solids handling.  Highly sensitive solids prone to attrition include fragile granules (kitty litter), finished food products (chips), plastic pellets, and sugar or salt.

Bin

Container for bulk solids with one or more outlets for withdrawal, either by gravity alone or by flow-promoting devices which assist gravity

[popover image=”/your-need/poor-flow/hopper-flow-obstruction-arching-bridging/” link_text=”Bridging” title=” ” content=”A costly no-flow problem” direction=”right”]

Same as arching (a no-flow condition)

Bunker

Same as bin, often used in reference to storing coal

Chute

Means of collecting or directing material stream, which, unlike a hopper, does not operate full

Cylinder

Vertical part of a bin which has a constant cross-section; can be any shape

[popover image=”/engineering/pneumatic-conveyors/pneumatic-dense-phase-4/” link_text=”Dense phase conveying” title=” ” content=”Dense phase transport” direction=”right”]

This occurs when particles are conveyed in the gas stream at a velocity that is less than the saltation velocity. Two general modes of flow can result in dense phase, and are referred to as plug or piston flow and moving bed (dune) flow.

[popover image=”/engineering/pneumatic-conveyors/pneumatic-dilute-phase-4/” link_text=”Dilute phase conveying” title=” ” content=”Dilute phase transport” direction=”left”]

This occurs when particles are conveyed in the gas stream at a velocity that is greater than the saltation and choking velocities.

Discharger

Device used to enhance material flow from a bin but which is not capable of controlling the rate of withdrawal

Effective head

Convenient way to express consolidating pressure by dividing it by bulk density

Elevator

Same as bin, often used in reference to storing grains

[popover image=”/your-need/poor-flow/hopper-flow-pattern-expanded-flow/” link_text=”Expanded flow” title=” ” content=”Discharge pattern combining positive features of funnel flow with mass flow”]

Flow pattern that is a combination of mass flow and funnel flow

Feeder

Device for controlling the rate of withdrawal of bulk solid from a bin

Flooding, flushing

Condition where an aerated bulk solid behaves like a fluid and flows uncontrollably through an outlet or feeder

Flow channel

Space in a bin through which a bulk solid is actually flowing during withdrawal

Flow properties test report (FPTR)

Jenike & Johanson’s bulk material characterization report typically containing results for a material’s cohesive strength, bulk density range, coefficient of sliding friction against hopper wall surfaces, moisture content, particle size distribution, and permeability.  These are the core characteristics needed to properly design a mass flow bin and feeder.

Fluidization

Using air or inert gas to fully aerate a fine bulk solid to allow it to behave as a liquid

[popover image=”/your-need/poor-flow/hopper-flow-pattern-funnel-flow-cohesive-material/” link_text=”Funnel flow” title=” ” content=”Discharge pattern occurring in silo, bin, bunker, or hopper” direction=”right”]

Flow pattern in which solid flows in a channel formed within stagnant material

Hopper

Converging part of a bin

[popover image=”/your-need/poor-flow/hopper-flow-pattern-mass-flow/” link_text=”Mass flow” title=” ” content=”Discharge pattern occurring in silo, bin, bunker, or hopper” direction=”right”]

Flow pattern in which all solid in a bin is in motion whenever any of it is withdrawn

Pickup velocity

This is the gas velocity at the pick up point of the conveying system where solids are introduced into the conveying gas stream.

Piping

Same as ratholing

P-FACTOR

The ratio of the applied solids compacting pressure to the solids pressure during steady gravity flow

[popover image=”/your-need/poor-flow/hopper-flow-obstruction-ratholing/” link_text=”Ratholing” title=” ” content=”A costly no-flow problem” direction=”right”] 

A no-flow condition in which material forms a stable vertical hole within the bin

Saltation velocity

The gas velocity at which particles fully suspended within a horizontal conveying line begin to drop out of suspension and settle in a layer on the bottom of the pipeline.

[popover image=”/your-needs/segregation-sifting-pile-5/” link_text=”Sifting segregation” title=” ” content=”Sifting segregation mechanism” direction=”right”] 

Separation of bulk solids by their size, shape, or particle density.  There are several ways bulk solids can separate. 

Silo

Same as bin

State diagram

The plot of pressure drop as function of conveying gas velocity over range of solids loading.  This diagram defines conveying modes of dilute and dense phase transport.

[back_to_top]

If you have not found the information you are seeking, please [modal_contact link_text=”contact us”].