Study of electric arcs in an air-steam mixture in AC plasma torches

A review of existing plasma torches designed for steam plasma is presented in this paper. Together, they cover the following ranges of key technical parameters: efficiency from 51 to 95%, enthalpy of the plasma from 12 to 84 MJ/kg, and the fraction of the steam in the plasma forming gas from 17 to 100%. The advantages of alternating current to produce plasma is grounded. The problems of creating of a steam plasma torch are described. The description of the experiments carried out on the AC plasma torch, during which the total flow of the plasma forming steam-air mixture and the effective value of the current remained constant ∼ 6.7 g/s and ∼ 28.4 A, respectively, and the steam content ranged from 54 to 85%, is given. With an increasing proportion of steam, the voltage increased from 1.03 to 1.59 kV, while the estimated temperature of the arc decreased from 11600 to 10200 K, which is caused by intensification of heat transfer. In all modes, there was a high efficiency of 94.3–95.3% with a significant change in the specific energy input from 8.3 to 12.4 MJ per 1 kg of plasma-forming gas.