Fluidization regimes
Fluidization techniques

For a given particle bed, the state of the suspension changes as a function of the fluidization rate. By progressively increasing the fluidization rate (in practice, we will use the notion of fluidization speed, which corresponds to the speed in an empty drum), we observe the following phenomena (figure 1):

• at very low gas velocities, the particles are immobile. No fluidization occurs;

• at a speed U_mf which we'll call the minimum fluidization speed, particles move slightly and become suspended. The suspension remains homogeneous and no bubbles appear under this condition;

• at a speed slightly...