(341d) Experimental Investigation Of Rotating Fluidized Beds In A Static Geometry

Rotating fluidized beds in a static geometry are experimentally investigated. To introduce the rotating motion and the tangential fluidization of the particle bed, the fluidization gas is injected tangentially in the fluidization chamber via multiple gas inlet slots. The radial fluidization of the particle bed is introduced by forcing the gas to leave the fluidization chamber via a centrally positioned chimney. The fluidization behavior of both large diameter, low density polymer particles and small diameter, higher density salt particles is investigated at different solids loadings in a 24 cm diameter, 13.5 cm long non-optimized fluidization chamber. The behavior of the rotating fluidized bed is very different for the polymer particles and the salt particles. Whereas the polymer particles tend to form a dense and uniform bed, the salt particles tend to form a less dense and less uniform bed. Bubble formation is observed with the salt particles. A rotating fluidized bed and an acceptable gas-solid separation is obtained provided that the solids loading and the particle bed rotational speed (i.e. the gas flow rate) are sufficiently high. To allow a sufficiently high solids loading to build up, particles losses via the chimney have to be minimized. With both types of particles, slugging and channeling, that is, a non-uniform distribution of the gas over the gas inlet slots to the fluidization chamber may occur at too low rotational speeds or too low solids loadings. Static pressure profiles in the fluidization chamber are studied and shown to be a good indicator of channeling or slugging. To correctly balance the centrifugal force and the radial gas-solid drag force, an optimization of the fluidization chamber design and of the operating conditions for each given type of particles is shown to be necessary. Scale-up to a 36 cm diameter fluidization chamber is studied and scale-up rules are explained.