Electrostatic precipitators
Sneakage
Also known as gas sneakage, sneakage flow.
Sneakage is the portion of flue-gas flow that bypasses the active electrostatic field of an ESP — typically through the hopper void below the plates or the gas space above the plate stack — and exits without being electrostatically cleaned. Sneakage flow directly reduces collection efficiency because dust in the bypass stream is never charged.
Where sneakage occurs
- Hopper sneakage — gas short-circuits between fields by passing through the inverted-pyramid hopper void
- Anti-sneakage baffles — installed to block hopper paths; if damaged or missing, sneakage rises
- Penthouse and top-gas-distribution paths above the plate stack
- End-wall gaps between plates and the ESP casing
Well-designed ESPs limit total sneakage to 5–10% of gas flow; poorly maintained ESPs can run 20% or higher.
Sneakage and ash bridging
Hopper sneakage is worse when the hopper is full or bridged — the gas finds a path around the dust mass instead of being properly sealed off by it. Acoustic horns that keep hoppers flowing eliminate one common cause of sneakage indirectly, by ensuring the hopper itself remains a sealed gas-flow boundary.
Related terms
Related terms
- Electrostatic precipitatorAn ESP removes particulate from flue gas by charging dust and collecting it on plate electrodes. Sonic horns are widely used to dislodge ash from plates and to keep hoppers from bridging.
- Turning vaneTurning vanes at the ESP inlet straighten and evenly distribute the flue-gas flow before it enters the plate stack. Fouling on the vanes degrades distribution and collection efficiency.
- Collection efficiencyCollection efficiency is the fraction of inlet particulate captured by an ESP, baghouse or cyclone. Reported as a percentage; modern ESPs achieve 99.5%+, baghouses 99.9%+.