Showing papers by "Robert Pfeffer published in 1999"

Particle mixing in rotating fluidized beds: Inferences about the fluidized state

Abstract: Particle motion in a rotating fluidized bed was studied by observing the mixing of two layers of particles of different colors. The particles in the two layers were either nearly identical, except for their color, or were of different density and size distribution. All of the particles were in the Geldart-A classification for conventional fluidized beds. After fluidization, but before mixing, the bed exhibited some fluid-like behavior, that is, the inner surface became radially uniform. For particle layers of the same material, mixing occurred after U{sub mfc} was reached, with bubbles observed at the mixing velocity. No experimental difference between U{sub mb} and U{sub mfc} could be discerned; they either coincided or were nearly equal. Bubbles appeared to be responsible for particle motion and mixing. When the denser particles are placed on the distributor, the mixing behavior was similar to that observed for layers of the same material. However, when the less dense particles are placed on the distributor, mixing is dominated by differences in density and occurs before bubbles are visible.

Method of particle coating

Abstract: Coater for coating particles is provided with a casing and a cylinder having apertures rotatably mounted within the casing. Gas is blown into the casing and onto the host particles through the slots of the cylinder. Guest particles may be inserted into the casing initially or subsequently after rotation of the cylinder begins. The particles are fluidized when a balance is attained between the centrifugal force from the rotation of the cylinder and the force exerted upon the particles from the air flow. The centrifugal force exerted on the particles within the cylinder in an operating state is at least about 25 gs so as to cause guest particles of different sizes to be coated onto the host.