Reduced Size Model Study of Two Air Classifiers

The dynamics of shredded refuse in two one-quarter-scale air classifiers is studied both analytically and experimentally. The analytical model is based on an isolated single refuse particle that is acted upon by the air flow through the classifier and by gravity. The model is used to predict the value of the air speed necessary to keep a particle suspended at one place along the classifier flow channel. For a given air speed, the model is also used to predict the displacement of the particle along the flow channel for a rotary drum air classifier. Tests using quarter-scale models of a zig-zag and a rotary drum air classifier showed that the analytical fluidizing speeds and particle displacements were in good agreement with the experimental values when using a large number of particles from one component of an actual shredded refuse sample. A procedure for using the reduced scale results in the design of full size air classifiers is considered.