Boilers
Reheater
Also known as reheaters, reheat section.
A reheater is a tube bank in a boiler's convective pass that re-superheats steam returning from the high-pressure (HP) turbine before it enters the intermediate-pressure (IP) turbine. Reheat improves overall plant efficiency and reduces steam moisture content in the LP turbine stages.
Where it sits
In a typical utility-boiler convective pass, the reheater sits between the secondary superheater and the primary superheater, in a temperature range that recovers heat efficiently without exceeding tube-metal limits. Some boilers have two reheat stages.
Fouling
Reheater fouling follows the same pattern as the convective superheater: bonded ash on tube surfaces, occasional slag bridging in extreme cases. Outlet steam-temperature deviation is a leading symptom — falling reheat outlet temperature signals fouling reducing heat absorption.
Cleaning
Sonic horns are well suited to reheater cleaning because the deposits are predominantly dry. Combined with periodic steam sootblowing, they maintain reheater outlet temperature and protect the unit's heat rate.
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.
- Convective pass and backpassThe convective pass is the downstream section of a boiler where heat transfer is by conduction across tube banks: superheater, reheater, economiser. The primary zone for sonic-horn cleaning.
- 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.