Boilers
Pulverised-coal boiler
Also known as PC boiler, pulverised coal boiler, pulverized coal boiler.
A pulverised-coal (PC) boiler grinds coal to a fine powder in pulverising mills and injects it through burners into a furnace, where it burns in suspension at 1,400–1,700 °C. PC boilers are the dominant utility-scale boiler design worldwide and remain the workhorse of legacy coal-fired generation in Asia, India, Africa, Eastern Europe and parts of the Americas.
Layout
A typical PC boiler has tangential, wall-fired or down-fired burner arrangements with waterwalls absorbing radiant heat from the furnace; gas then passes over superheaters, reheaters, economisers and finally air heaters before reaching the ESP or baghouse.
Fouling pattern
- Slag on waterwalls and finishing superheaters
- Bonded ash on convective superheater and reheater tube banks
- Bridging deposits in the economiser hopper
- Ammonium-bisulphate fouling on the air-heater cold end (if SCR is installed upstream)
- Hopper bridging on the ESP and baghouse
Sonic horns installed across the convective pass attack the second through fourth of these continuously, complementing steam sootblowers on the slag-bonded superheater.
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.
- Circulating fluidised-bed boilerA CFB boiler burns fuel in a turbulent bed of sand, ash and limestone circulated by an upward-flowing gas stream. Tolerates coal, biomass, RDF and lignite; produces low NOx.
- WaterwallWaterwalls are panels of vertical evaporator tubes welded into a gas-tight membrane that line the furnace. They absorb radiant heat and produce most of the boiler's steam.
- 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.
- 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.
- 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.