“Conventional” rotating fluidized beds, that is rotating fluidized
beds in a rotating geometry, balance the centrifugal force
with the radial gas–solid drag force [1–10]. The centrifugal
force is generated by rotating the reactor or fluidization chamber
fast around its axis of symmetry by means of a motor. The
particles form a cylindrically shaped particle bed that is radially
fluidized by injecting the fluidization gas through the outer
cylindrical wall of the fluidization chamber, typically a porous
or sintered wall. The fluidization gas leaves the fluidization
chamber via a centrally positioned chimney. The cylindrical
shape of the fluidized bed allows a more compact construction.
The centrifugal force can be a multiple of gravity, allowing
higher fluidization gas velocities than in conventional (that is
gravitational) fluidized beds. Increased gas–solid slip velocities
improve inter-phase mass and heat transfer. This opens
perspectives for the use of conventional rotating fluidized
beds with highly exothermic or endothermic reactions [10],
very fast reactions, etc.. Furthermore, a more uniform fluidization
is obtained at high centrifugal forces. Finally, interparticle
van derWaals forces can be overcome, allowing to fluidize very
fine particles, such as cohesive (Geldart group C) micro- and
nano-particles
Despite their advantages, conventional rotating fluidized
beds have never been introduced in the large-scale industries.
Both the use of a motor and the rotating geometry pose serious
challenges to their practical use. Particular challenges are
encountered with mechanical vibrations, sealing (i.e. the need
for a rotating seal) and particle feeding/removal to/from the
fluidization chamber and continuous operation. The new concept
of a rotating fluidized bed in a static geometry eliminates
these challenges and is experimentally investigated in this work.