Baghouses
Differential pressure (baghouse)
Also known as baghouse ΔP, baghouse delta-P, filter ΔP, baghouse dP.
Differential pressure (ΔP) across a baghouse is the pressure drop between the dirty-gas inlet plenum and the clean-gas outlet plenum. ΔP is the headline operational KPI for any fabric filter: too low signals broken bags or open compartments, too high signals fouling, bridging or blinding.
Typical operating bands
| Application | Normal ΔP | Alarm | Trip |
|---|---|---|---|
| Cement pulse-jet | 8–15 mbar (3–6 inWG) | 20 mbar | 25 mbar |
| Coal utility reverse-air | 10–18 mbar | 22 mbar | 28 mbar |
| WtE pulse-jet | 12–20 mbar | 25 mbar | 32 mbar |
| Light industrial pulse-jet | 5–12 mbar | 18 mbar | 25 mbar |
Why operators obsess over ΔP
Every additional mbar of ΔP costs ID-fan power and reduces plant throughput. A 5-mbar ΔP rise on a large coal-fired baghouse can mean hundreds of kW of additional fan power and the loss of a few MW of derate-induced generation. Sustained high ΔP also accelerates bag blinding and triggers premature bag-change campaigns.
How sonic horns reduce ΔP
Sonic horns keep the bag-surface cake from consolidating into the medium between primary cleaning cycles. Pulse-jet, reverse-air or shaker cleaning then has less work to do and removes a larger fraction of the cake. Plants retrofitting sonic horns commonly see 2–5 mbar ΔP reduction and 25–40% extension of bag life.
Related terms
Related terms
- Fabric filterA fabric filter removes particulate from a gas stream by passing it through woven or felted bag media. Sonic horns supplement primary cleaning and reduce differential pressure.
- BaghouseA baghouse is the structural enclosure that holds the bags, cages, tubesheet, cleaning system and hoppers of a fabric-filter dust collector. Sized in compartments for online isolation.
- Filter cakeFilter cake is the dust layer that builds up on the surface of a baghouse filter bag. The cake itself does most of the fine-particle filtration; cleaning balances cake build-up against ΔP.
- Bag blindingBag blinding is the choking of filter-bag pores by dust embedded within the medium. It raises differential pressure permanently and is the leading cause of premature bag replacement.
- Pulse-jet cleaning cycleThe pulse-jet cleaning cycle is the firing pattern of compressed-air pulses across a baghouse. Tuned by pulse duration, interval and ΔP set-point to balance cleaning against bag wear.
- 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.