Multiphase stationary plasma generators working on oxidizing media

Abstract

The subject of this paper is the design of two types of stationary multiphase ac plasma generators, developed for plasma chemical methods of waste destruction and processing (including syngas production). This paper presents plasma generators of average power (up to 50 kW) and high power (up to 500 kW) working on oxidizing media and describes the basic physical processes in the discharge chamber of a multiphase low-temperature (thermal) plasma generator. The presence of diffuse mode of arc burning at ne ∼ 1014–1015 cm−3 and contracted mode ne ⩾ 1016 cm−3 is detected. The external characteristics (dependence of working gas heat content, power in arcs and efficiency on flow rate) based on experimental data are presented. The influence of plasma forming gas variation on electric parameters is demonstrated. The powerful multiphase plasma generator works at atmospheric pressure on oxidizing media (air) in the power range 100–500 kW and the flow rates 10–70 g s−1 with thermal efficiency of 70–90% and electrode lifetime of more than a hundred hours. The thermal efficiency of an average power (up to 50 kW) plasma generator in the range of air flow rate of 2–25 g s−1 is 80–95%, while the electrode lifetime is hundreds of hours. The described multiphase plasma generators allow the working gas heat content to be controlled in a wide range at the outlet (for air—from 1.5 MJ kg−1 up to 12.5 MJ kg−1), which is important for the realization of plasma technologies, including syngas production.