Fluidized Bed
Fluidized Bed is a state-of-the-art technology used for the combustion of biomass and other solid fuels. Its fundamental principle is the creation of a bed of particles consisting of fuel and an inert material and its “fluidization” by supplying an air stream underneath it. The air stream carries the bed particles, which mix and behave almost as a fluid.
Fluidized bed combustion allows for a good mixing of the fuel particles and the air and ensures a high heat capacity, which allows for almost complete combustion at lower temperatures than other technologies. This also minimizes the formation of certain pollutants. The technology is also more flexible in variations of fuel quality.
Fluidized bed combustion comes into two main varieties. In the Bubbling Fluidized Bed (BFB) variety, the air velocity at the bottom of the bed is such that creates a distinct fuel bed, the top layer of which appears as if it is a “bubbling” fluid. In the Circulating Fluidized Bed (CFB) version, the air velocity is greater and the inert particles are carried away by the flue gas. A cyclone is used to separate them from the gaseous stream and they are then recycled in the fuel bed.
