Glossary
Boilers
Bubbling fluidised-bed boiler
Also known as BFB boiler, bubbling fluidised bed, bubbling fluidized bed.
A bubbling fluidised-bed (BFB) boiler burns fuel in a bed of inert solids fluidised by an upward gas flow slow enough that the bed surface bubbles like boiling water but particles do not entrain into the flue gas. Compared with CFB, BFB uses lower fluidisation velocity, no external cyclone, and a simpler bed-management regime.
Where BFB is used
- Wet biomass and forest residues
- Sewage-sludge incineration
- Hog-fuel and bark boilers at pulp mills
- Small-to-mid capacity district-heating and process-steam duty
- High-moisture, low-calorific fuels generally
Fouling
The fouling pattern resembles a CFB but with less cyclone deposition. The convective pass, economiser and air heater accumulate fine ash; the waterwall above the bed can experience alkali-rich slagging on agricultural-residue and straw fuels. Sonic horns on the convective pass and air-heater cold end are the typical cleaning fit.
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.
- Hog-fuel boiler and bark boilerA hog-fuel or bark boiler burns wood residues, bark and screened biomass to provide auxiliary steam at pulp mills, complementing the kraft recovery boiler.