Written by John Evans, Technical Writer & Moderator for Webcast Experts℠, a division of Krishnan & Associates
Who does not remember those lovable GhostBusters – Bill Murray, Dan Akroyd, and Harold Ramis - as the slime blower wielding parapsychologists battling ectoplasmic residues (ghost slime) in New York City. (Sorry ladies, that new all-female paranormal police do not measure up for this blogger).
Every bit as challenging as the psychomagnotheric slime dealt with by the Ghostbuster’s proton packs is the formation of fouling, corrosion, and the formation of sticky, agglomerated ash formed on the fireside of biomass boilers. Ash forming elements including silicon, calcium and alkali metals (notably potassium) are prevalent in non-design opportunity fuels such as agro-wastes, pellets, and municipal solid wastes. During combustion, alkali metals are released as vapor phase alkali chlorides, hydroxides, and sulfates which cause fouling and corrosion. The sticky ash, formed when the alkali compounds in the fuel react with silica forming low-melting silicates, is also problematic for handling bottom ash where the formation of large clinkers adds to work time for removal.
These fouling, corrosion, and ash agglomeration issues all increase maintenance costs and decrease boiler availability. Periodic tube fireside cleaning adds expenses such as increased sootblowing and the use of explosives, not to mention the associated increased manpower. Further, the boiler tubes may require periodic repair or outright replacement.
So who ya gonna call? It does NOT have to be the ghost (slime) busters! Mineral-based fuel additives can be a preferable countermeasure for dealing with any of these deposit-related issues. Aurora™ (www.imerys-aurora.com) is such an additive that functions by capturing the alkali metals and incorporating them into compounds which remain solid at boiler temperatures thus avoiding the formation of the vapor phase chlorides, sulfates, and hydroxides. The solid compounds simply exit the boiler as bottom ash and fly ash. The issues of slagging, fouling, and corrosion are thus more easily managed or even eliminated.
So when confronted with these issues associated alkali metals in your fuels, consider that mineral-based additives like Aurora may let you say with confidence, “I ain’t fraid of no ghosts!”