Pulsed‐Flow Air Classification for Waste‐to‐Energy

Abstract

The development and testing of the concept of pulsed‐flow air classification for waste‐to‐energy production are discussed. Air classifiers, a potentially valuable unit operation in waste‐to‐energy production facilities, currently do not meet expectations. Standard designs generally lose large amounts of combustible material as well as produce a fuel that is high in metal and glass contaminants. Pulsed‐flow classification is presented as a concept which can avoid both pitfalls. Municipal solid waste (MSW) is composed of particles which can be cataloged as combustible and non‐combustible fractions by defining a density split between aluminum and plastic: generally all other non‐combustibles are more dense than aluminum, while all other combustibles are less dense than plastic. However, current designs for classifiers tend to separate by aerodynamic characteristics which do not always produce a split based on density alone. Pulsed‐flow classifiers are seen to offer a unique solution to this puzzle. In this paper, each aspect of theory and laboratory testing is presented, including: (1) Preliminary determination; (2) particle characteristics; (3) theory of pulsed‐flow classification; (4) experimental equipment; (5) laboratory testing; and (6) pulsed‐flow air classification for energy production. Conclusions from the research are summarized in the final section of the paper.