Core technology
Low-frequency acoustic cleaner
Also known as low frequency sonic horn, low-frequency horn, LF acoustic cleaner.
A low-frequency acoustic cleaner is an industrial sonic horn whose fundamental frequency sits in the 60–250 Hz band. The long acoustic wavelength — between 1.4 and 5.7 metres in air — projects further from the bell horn than higher-frequency designs, fills large open vessels more uniformly and is the default choice for cleaning bulky industrial equipment.
Why frequency choice matters
Acoustic energy at long wavelengths diffracts around obstructions (tube banks, electrode rows, baffles) instead of being absorbed or scattered. That makes low-frequency horns the appropriate selection where the cleaning target is several metres deep and partly obstructed — most large industrial vessels fall into this category. Higher-frequency horns concentrate more energy per unit volume but lose effectiveness in deep cavities; see high-frequency acoustic cleaner for the complementary case.
Typical applications
- Electrostatic precipitators — collecting-plate cleaning, hopper de-bridging
- Preheater cyclones and calciners in cement plants
- Kraft recovery boilers — superheaters, generating banks, economisers
- Air heater cold-end basket cleaning
- Large fly-ash hoppers, silos and bunkers
- HRSG harp-tube banks in combined-cycle plants
Indicative selection bands
| Band | Wavelength in air at 20 °C | Typical use |
|---|---|---|
| 60 Hz | ~5.7 m | Very large ESPs, recovery boilers, deep silos |
| 75 Hz | ~4.6 m | ESPs, preheater cyclones, large hoppers |
| 125 Hz | ~2.7 m | Mid-size ESPs, baghouse compartments, calciners |
| 230 Hz | ~1.5 m | Boiler convective passes, smaller hoppers, baghouses |
Related terms
Related terms
- Acoustic cleanerAn acoustic cleaner is any device that uses high-intensity sound waves to dislodge particulate fouling from inside industrial process equipment such as boilers, ESPs, baghouses and silos.
- 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.
- High-frequency acoustic cleanerHigh-frequency acoustic cleaners operate at 250–450 Hz. The shorter wavelength carries more energy per unit volume and suits fabric filters, SCR catalysts and small hopper geometries.
- Infrasonic cleanerAn infrasonic cleaner operates below the audible threshold (typically 12–30 Hz). The very long wavelength penetrates further than a conventional sonic horn and is preferred on recovery boilers and WtE flue paths.
- Bell hornA bell horn is the conical or exponential flare that amplifies and projects sound from an industrial sonic horn's driver into the vessel being cleaned.