Glossary
Hoppers and silos
Hopper
Also known as hoppers, storage hopper, process hopper.
A hopper is an inverted-pyramid or conical vessel designed to store bulk solids and discharge them through a converging outlet. Hoppers appear under ESPs, baghouses, economisers, air heaters and process equipment of every kind across cement, power, WtE, biomass, refining, pharma, food and mining.
Universal failure modes
- Bridging — stable arch forms above the outlet
- Rat-holing — narrow channel above the outlet; surrounding material packs and hardens
- Pluggage — total blockage that stops discharge
- Funnel flow vs mass flow — first-in, last-out behaviour leading to ageing material remaining indefinitely
Why acoustic cleaning works on hoppers
Sonic horns excel on hoppers because the geometry is small enough for the sound wave to fill the whole vessel and the dust is dry and friable. Compared with mechanical alternatives — bin vibrators, air cannons, whip hammers — they cause no structural stress, no fatigue, and no impact damage to the hopper itself.
Related terms
Related terms
- SiloA silo is a large vertical bulk-solids storage vessel. Cement, fly-ash, lime, biomass, fertilizer and food-powder silos all bridge and rat-hole; sonic horns are the leading flow aid.
- Bunker (coal bunker)A coal bunker is an intermediate coal-storage vessel that feeds pulveriser mills. Bridging in coal bunkers interrupts mill feed and forces unit derates; sonic horns are the standard flow aid.
- Bin (bulk-solids)A bin is a small-to-mid bulk-solids storage vessel. The term is used loosely; in industrial practice bins, hoppers and silos overlap in usage.
- Bridging (bulk-solids)Bridging (also arching) is the formation of a stable arch of bulk solids above the discharge outlet of a hopper or silo, stopping material flow. The universal failure mode of bulk-solids storage.
- Rat-holingRat-holing is a flow pattern in which material discharges through a narrow vertical channel above the outlet, while the surrounding material remains stagnant and consolidates.
- Mass flow and funnel flowMass flow is first-in-first-out: all material moves uniformly. Funnel flow is first-in-last-out: a central column moves while surrounding material stagnates.
- Sonic hornA sonic horn is a pneumatically-driven low-frequency sound emitter (typically 60–400 Hz at 140–180 dB SPL) used to dislodge particulate fouling from boilers, ESPs, baghouses and process vessels.