More than you wanted to know about CFB’s Harvie Beavers Lt USN(Ret); Former Project Mgr at Piney Creek LP; ARIPPA Past President.

More than you wanted to know about CFB’s

Harvie BeaversLt USN(Ret); Former Project Mgr at Piney Creek LP; ARIPPA Past President

• Versions of Circulating Fluid Bed ‘technology’ has been around for several decades in various forms having been used as ‘reactors’ for chemical conversion in Germany during WWII for liquid fuel production. Both that application and the ‘current’ design is generally thought to have been developed by the German Chemical Company Lurgi, although many ‘refinements’ have been created and advanced by others. Today the primary manufacturers of CFB units include but are not limited to Alstom, Foster Wheeler, Babcock & Wilcox, and Metso (formerly Tampella, Keeler Dorr Oliver and Kvaerner). Although each of these likes to believe their product is ‘unique’, all of them share the same common ‘design characteristics’; a combustion chamber, a ‘recirculation’ design with solid sizing capability, over-fire air, and a method to return material back to the combustion chamber.

• I’ve operated and maintained early B & W versions, Alstom, and ‘Tampella-Metso’ units for the last 20 years after departing 20 years in ‘nuke land’. I prefer the Tampella design, so that’s where most of the pictures are sourced from in the following presentation. I’ll try to point out ‘different’ ways the same function is accomplished by other designs.

• All of the designs basically consist of a large rectangular steel box into which fuel and massive amounts of air are mixed and burned/combusted. The ‘walls’ of all units are fabricated with tube panels that contain ‘water’ connected by ‘header pipes’ and ‘vented’ into a pressurized steam drum at the top of the steel box. All units have a device to ‘separate’ the large chunks of non-combusted fuel from the small chunks and combustion gas- most use a cyclone although ‘U-beams’ and torturous path separation is also used. All units recirculate the large chunks back to the lower section of the combustor for reuse. All units have ‘over-fire air’ above the normal area of combustion, some have more than one version of same.