Design and operating characteristics of water vapor plasma torch for environmentally friendly processes

Abstract

This research presents the application of the novel developed plasma technology for environmental protection. The following main tasks of this research have been carried out at Lithuanian Energy Institute: a) an experimental plasma torch facility has been designed and tested at Plasma Processing Laboratory; b) water vapor plasma generation was practically realized; c) thermal and electrical characteristics of novel designed plasma torch were investigated and plasma jet characteristics were established. An experimental DC (direct current) plasma torch of a linear scheme operating on gas-water vapor vortex at atmospheric pressure has been used. The button type hot tungsten-rod cathode working as electron emitter and confusortype cooper anode has been used to form the electric arc in the discharge chamber. All parts of plasma torch were water-cooled. The characteristics of plasma torch and the parameters of plasma jet were determined employing the theory of similarity while measuring current intensity in the electric arc column, voltage drop and gas flow rates. Experimental results confirmed that water vapor plasma has superiority over other plasma forming gas due to its unique properties – extremely high enthalpy, environmentally friendly conditions, relatively low cost and endless amount of plasma forming gas. This work also includes analysis of operating characteristics of plasma torch and plasma jet, which were investigated in the range of plasma source parameters: power of plasma torch 30-53 kW, electric current intensity 130-210 A, the voltage 230-330 V, the efficiency 0.58-0.78, the mean temperature of plasma jet at the torch exhaust nozzle 23002900 K and mean velocity 340-700 m/s. The analysis of obtained results shows that this plasma technology could be easily employed for environmental protection such as destruction of hazardous substances and conversion of biomass to synthetic gas.