Hoppers and silos
Air cannon
Also known as air blaster, air cannons, air blasters, pneumatic blaster.
An air cannon (also air blaster) is a pressure-vessel and quick-release-valve assembly that fires a brief high-pressure air pulse — typically 5–7 bar from a 30–150 litre reservoir — through a nozzle directed into a hopper, silo or duct. The pulse disrupts material bridges and dislodges build-up. Air cannons are widely deployed in cement plants, coal-fired power plants, WtE plants and bulk-handling installations.
Strengths and weaknesses
| Strength | Weakness |
|---|---|
| Very high instantaneous energy | Causes documented structural stress and fatigue |
| Effective on consolidated bridges | Discrete pulses leave time for bridges to re-form |
| Established technology, broad supplier base | Episodic high air consumption |
| Targets specific build-up zones | Requires array of cannons for large silos |
| Tolerates high temperature | Pulse can disturb downstream flow control |
Air cannon vs sonic horn
Sonic horns compete directly with air cannons across most flow-aid duty. Sonic horns favour: continuous prevention over periodic remediation, non-contact operation, single-unit coverage of an entire vessel, and zero structural stress on the vessel itself. Air cannons favour: very hard consolidated bridges and applications where the higher impact energy is decisive.
Many real installations use both: sonic horns for continuous prevention, with a small number of strategically-placed air cannons reserved for restart after extended shutdowns or to break unusually-hard bridges.
Related terms
Related terms
- Anti-bridging deviceAn anti-bridging device is any flow-aid hardware installed to prevent or break material bridging in a hopper or silo: sonic horns, air cannons, vibrators, fluidisation pads.
- HopperA hopper is an inverted-pyramid or conical vessel for storing and discharging bulk solids. Bridging and rat-holing are the universal failure modes; sonic horns are a clean, low-maintenance remedy.
- 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 vibratorA bin vibrator is a pneumatic or electric vibrator bolted to the outside of a hopper or silo to dislodge bulk-solids bridges. Compact but can compact wet powders and stress the vessel.
- 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.