Glossary
Baghouses
Bag blinding
Also known as filter bag blinding, bag binding.
Bag blinding is the choking of a filter bag's pore structure by dust that has worked its way into the fabric itself rather than remaining on the surface. Once embedded, the dust cannot be released by any normal cleaning cycle; differential pressure rises and stays high. Blinding is the leading cause of premature bag replacement on most industrial baghouses.
When blinding accelerates
- Acid dew-point excursions — condensed acid bonds dust into the fabric
- Hygroscopic dust — moisture pickup turns surface dust into a wet paste
- Tar or oil aerosol in the inlet gas
- Excessive bag-velocity (air-to-cloth ratio) — forces particulate into the pores
- Sub-micron ash from WtE or biomass
Mitigation
- Maintain gas temperature above the acid dew point (typically 130–150 °C)
- Use PTFE-membrane bags for surface filtration where chemistry warrants
- Right-size the baghouse so air-to-cloth ratio stays moderate
- Use sonic horns to keep cake from consolidating into the medium before each pulse
Distinguishing from cake bridging
Cake bridging is a cake-on-surface problem and is fixable with better cleaning. Blinding is dust-in-fabric and is not fixable without bag replacement.
Related terms
Related terms
- Cake bridging and cake blindingCake bridging is dust connecting adjacent bags so the cleaning pulse no longer reaches the surface. Cake blinding is pore choking that raises ΔP and reduces filtration.
- 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.
- Filter bagA filter bag is the cylindrical fabric sock that traps particulate inside a fabric filter. Media selection depends on temperature, gas chemistry, dust load and cleaning cycle.
- Differential pressure (baghouse)Differential pressure (ΔP) across a baghouse is the pressure drop between dirty and clean plenums. It is the headline operational KPI: too low signals broken bags, too high signals fouling.
- 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.