Development of an acoustic levitation apparatus for a coal pyrolysis study

An acoustic levitator was designed and constructed to hold coal particles stationary in air. It consisted of a simple, single axis driver-reflector system that allowed for optical focusing, observation and photography. One at a time, particles were suspended in a standing ultrasonic wave, then heated with focused thermal radiation. The main advantages of this study were being able to clearly view a known particle reacting because only single particles were used and holding that particle in position without any solid body contact when heating.

The behavior of particle heating in the levitator was observed through a microscope and noted. With heat application, particles were seen to roll out, explode out or jet out of position. The external restructuring, upon softening, of a few coal particles was magnified and captured on film. This research demonstrated the development of an acoustic levitation apparatus as a potentially improved coal pyrolysis experiment over previous experiments.