Glossary
HRSG and gas path
Diverter, louver and guillotine dampers
Also known as diverter damper, louver damper, guillotine damper, isolation damper.
Dampers route, isolate or modulate flue-gas flow inside industrial ducting. Three principal types appear in power and process plants:
| Damper | Function | Typical position |
|---|---|---|
| Diverter damper | Swings flow between two ducts | HRSG bypass / GT exhaust diverter |
| Louver damper | Multiple parallel blades for throttling and partial isolation | Flue-gas distribution, ID-fan modulation |
| Guillotine damper | Full isolation by sliding plate | Boiler outlet isolation, baghouse compartment isolation |
Damper-related failure modes
- Sticking — particulate accumulation in blade slots or guillotine guides prevents free movement
- Seal failure — eroded or compacted seals leak isolation-critical flow
- Blade fouling — distorts the designed flow pattern and creates uneven distribution
- Slow stroke time — fouled actuators or guides take longer to operate than design
Sonic horns on damper areas
Sonic horns installed adjacent to damper assemblies help keep blade and seal areas clear of accumulating particulate, preserving stroke time and isolation integrity. This is particularly valuable on HRSG diverter dampers where slow stroke time delays plant start-up.
Related terms
Related terms
- Heat Recovery Steam GeneratorAn HRSG recovers heat from a gas turbine's exhaust to generate steam, the second cycle of a combined-cycle plant. Finned-tube ash deposition and ABS fouling are the main cleaning concerns.
- Combined-cycle gas turbineA CCGT plant combines a gas turbine with a steam turbine driven by an HRSG recovering exhaust heat. Plant efficiency reaches 55–62% LHV; HRSG cleanliness is critical.
- ID, FD and PA fansBoilers use three fans: ID (induced draft) pulls flue gas through the convective pass, FD (forced draft) pushes combustion air, PA (primary air) conveys pulverised coal to the burners.
- 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.