Alternative cleaning
Water cannon
Also known as smart water cannon, water gun, water lance (waterwall).
A water cannon projects a high-pressure water jet onto boiler waterwall tubes to crack slag deposits by thermal shock. The rapid temperature differential between the cool water and the hot slag fractures the bonded slag layer, allowing the next portion to fall away. Water cannons are the standard cleaning tool for furnace slagging on coal-fired and biomass utility boilers.
Aimed shots, not sweeps
Modern smart water cannons (notably Clyde Bergemann) are computer-controlled to aim specific shot patterns at known fouling zones. Operators see a heat-flux map from radiant-section thermocouples; the cannon fires shots calibrated to the slag thickness in each zone. Compared with manual aiming, this dramatically reduces water consumption and tube-fatigue risk.
Trade-offs
- Tube fatigue — repeated thermal cycling can crack tubes at the impingement zone over years of service
- Water consumption — substantial volumes of demineralised water needed
- Slag knock-down hazard — large fallen slag pieces can damage waterwall lower zones
- Effective only on slag — does not address dry friable deposits on convective surfaces
Sonic horns are not effective on furnace slag and water cannons are not effective on dry convective-pass deposits. The two technologies serve different zones of the boiler and do not directly compete.
Related terms
Related terms
- Water lanceA water lance is a handheld or fixed water-jet cleaning device used during boiler outages or, in fixed designs, for slag-melt zones during operation.
- 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.
- SlaggingSlagging is the deposition of molten or semi-molten ash on radiant and high-temperature surfaces in the boiler furnace. Hard, bonded; usually requires water cannons or explosive deslagging.
- Steam sootblowerA steam sootblower projects high-pressure steam jets onto boiler tube banks to dislodge soot and ash. Effective but causes documented tube erosion and consumes valuable boiler steam.