| This dissertation applies a theoretical model based on a fluid mechanical force balance to the concept of pulsed-flow air classification. The model is developed, calibrated, used, and tested.; It is in their application in resource recovery that air classifiers have the most difficulty in meeting separation requirements. The characteristics of feed particles, especially as they pertain to separation, are discussed. Pulsed-flow air classification is seen as a technology which can achieve a much cleaner product.; The theory of pulsed-flow air classification involves a combination of characteristics that has not been widely studied. The largest amount of work in the theoretical formulation is devoted to the acceleration effect, due to its importance in time-varying flow. Previous modeling efforts have been largely statistical, and it is difficult to extrapolate from their results. This research derives and calibrates a deterministically-based model, which is useful in designing an active pulsed-flow air classifier.; A laboratory air classifier capable of providing a large range of experimental conditions, including pulsed airflow, is designed, built, and instrumented.; Both the computer model and laboratory analysis show that active pulsed-flow air classification produces significantly better separation than the other designs tested. Experience in the laboratory shows that the actual operation of an active pulsed-flow air classifier has several advantages over a zig-zag air classifier, which is the most common device in current use. |
