Glossary
Fouling
Forced outage
Also known as unplanned outage, forced shutdown, emergency shutdown.
A forced outage is an unplanned shutdown of an industrial unit, triggered by equipment failure (typically boiler tube failure) or by pressure-vessel safety conditions that cannot be tolerated in continued operation. Forced outages are tracked as a percentage of operating hours (forced outage rate, FOR) and contrast with planned outages scheduled in advance.
Economic cost
Forced outages dominate the economic cost of poor cleaning practice:
- Coal-fired utility (500 MW) — typically $0.5–1.5 million per day of forced outage, depending on power-market price
- WtE plant (40 MW + tipping-fee revenue) — $0.3–0.7 million per day including lost gate fees
- Pulp-mill recovery boiler — typically $0.4–1.0 million per day of mill production interruption
- Cement plant (5,000 t/day) — $300–600k per day of lost clinker
Fouling-driven forced outages
- ESP hopper pluggage forcing the field offline
- Baghouse ΔP tripping the ID fan
- Cement kiln-inlet snowmen requiring manual cleaning
- Recovery boiler superheater pluggage demanding chill-and-blow
- HRSG ΔP excursion derating the gas turbine
Sonic horns attack the root cause — early fouling — before it reaches the level that forces outages.
Related terms
Related terms
- Boiler tube failureBoiler tube failures are the leading cause of forced outages on industrial boilers. Causes range from creep and erosion to corrosion and overheating; cleaning practices contribute to several.
- Fouling (general)Fouling is the accumulation of unwanted deposits on process-equipment surfaces. The general umbrella term covering slagging, scaling, coking, sintering and many other specific mechanisms.
- DerateA derate is operation below nameplate capacity because a limiting condition has been reached. Fouling-driven derates from ID fan, ΔP or boiler tube limits are common.
- 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.