Widening of Fluidized Bed Combustion Fuel Scale - A Novel Method to Inhibit Bed Agglomeration Problems in Fluidized Bed Boilers

摘要

Fluidized bed combustion (FBC) technology was commercialized in the 70s. Both bubblingrnfluidized bed (BFB) and circulating fluidized bed (CFB) technology are capable of handling arnwide variety of solid fuels. However, today’s trend, towards inexpensive and greener biomassrnbased energy sources, sets new challenges to fluidized bed technology as well as otherrncombustion technologies. Properties and behavior of fuel ash may limit the use of these fuelsrndue to bed agglomeration, fouling and corrosion problems.rnPlywood residue, a good example of new fuel with special properties in commercial fluidizedrnbed applications, makes up a significant proportion of the fuel used in fluidized bed boilers atrnplywood factories. The ash of plywood residue is high in alkali and reacts with the sand,rnwhich is typically used as the fluidizing material in fluidized bed boilers. The reactionsrnbetween alkali and the sand produces low melting point compound. These compounds act asrnan adhesive between fluidized bed particles and result in serious bed agglomerationrnproblems, which disturbs continuous operation of the boiler. This problem can be avoided byrnusing AGGLOSTOPTM quartz-free bed material.rnThe concept of using AGGLOSTOPTM quartz-free bed material with high alkali fuels hasrnbeen successfully applied in two industrial scale BFB boilers (15 and 74 MWth). The methodrnhas been demonstrated with good results at the Schauman Wood Kuopio, 15 MWth boiler. AtrnKuopio the main fuels are plywood residue and birch bark. AGGLOSTOPTM quartz-free bedrnmaterial is also being used in a new 74 MWth bubbling fluidized bed boiler installed at thernPellos Plywood Mill in Ristiina, Finland. Pellos, another Schauman Wood Mill, is the biggestrnplywood factory in Europe and one third of the boiler fuel is plywood residue.rnAGGLOSTOPTM fluidized bed material which eliminates the adverse effects of solublernalkaline in the fluidized bed, can be applied to many other demanding and potential fuelsrnsuch as chipboard, brown stock residue, olive waste and energy crops.