Boilers
Attemperator and desuperheater
Also known as attemperator, desuperheater, spray attemperator.
An attemperator (or desuperheater) sprays demineralised water into superheater or reheater steam to control outlet temperature. The water flashes to steam, lowers temperature by mixing, and is then re-superheated in subsequent tube banks. Attemperator action is the primary control loop for superheater outlet temperature.
Why attemperation flow indicates fouling
When a superheater is clean, the tubes absorb the designed amount of heat from flue gas and the attemperator removes a known amount of excess to hit the steam set-point. As fouling reduces heat absorption, the steam emerging from the superheater is cooler than designed, attemperator flow falls, and the operator sees the cooler steam as a process drift.
Falling attemperation flow at constant load is one of the earliest signs of progressive superheater fouling. Performance engineers track it as a leading indicator before heat rate drift becomes obvious.
Sonic-horn relevance
Restoring attemperation margin by sonic-horn cleaning of superheaters and reheaters is a frequently-quoted commissioning result: a unit with falling attemperation flow regains 5–15 °C of headroom within weeks of horn installation.
Related terms
Related terms
- BoilerA boiler is a vessel that converts fuel chemical energy into steam by heating water. Coal-fired, biomass, oil, gas and recovery boilers all foul; sonic horns clean heat-transfer surfaces.
- SuperheaterA superheater is a tube bank that raises steam temperature beyond the saturation point using flue-gas heat. Sticky alkali ash and slag deposits are the dominant fouling concerns.
- ReheaterA reheater is a tube bank in the boiler's convective pass that re-superheats steam returning from the HP turbine before it enters the IP turbine.