Defluidization Investigation into Bubbling Fluidized Bed Particles with Alkaline Addition during Pyrolysis

Abstract

Some unwanted inorganic materials, such as alkaline compounds contained in biomass, have the potential to create slagging formations with oxide compounds from either inside or outside the bubbling fluidized bed (BFB). The process involved 88-125 µm silica sand and clay (bentonite) as bed particles during pyrolysis with KCl addition at 700°C to represent biomass under superficialN2-velocity operation. Agglomeration formation was confirmed by the decrease in the average ΔP of the experiment, which theoretically should take place during the addition of KCl, while the defluidization condition was confirmed by a consistent average ΔP particle deviation, even after further KCl additions. Investigation of 0.005 and 1 g encapsulated KCl periodical addition showed that the silica sand has a tendency to form agglomeration faster than bentonite, specifically after 0.0211 g of KCl addition (0.0032% of total silica sand mass). Meanwhile, the bentonite has a tendency to achieve defluidization formation more easily than silica sand according to deviation analysis. The ability of silica sand to maintain fluidization longer than bentonite indicates that silica sand is the better particle for this process.