Stabilization of thermal plasma in an AC plasma generator

A simple-structured thermal plasma generator for waste gas treatment has been studied. The thermal plasma technology applied to waste treatment has undoubtedly gained high importance owing to its outstanding properties such as flexibility, compact reactor, and clean treatment. Moreover, the thermal plasma generated by ac power has some additional advantages such as simple electrode system and easy maintenance. A prototype 200 kW class plasma generator with specifications of 10-30 m/sec gas velocity and 3000-5000 K temperature on the center just outside of the nozzle has been designed and tested. Case studies on heat transfer, heat flow, velocity distribution, and temperature distribution using a commercial simulation package show lots of flexibility in design. The experimental results from the prototype generator show that the ac thermal plasma is easily controlled by working gas flow once it is ignited. A stabilization condition is discussed with the data from monitoring arc voltage drops with respect to gas flow rate during the test.