Characterization of nitrogen thermal plasma torch: electric and gas pressure effects

Abstract

The industrial applications of thermal plasma technology, particularly in material processing, have attracted considerable attention worldwide. Plasma torch is a tool that has proven its efficacy for industrial use by thermal arc plasma production. In this study, after designing and manufacturing a non-transferred type of DC plasma torch, its electrical, chemical, and thermodynamic characteristics were investigated with nitrogen working gas and variable parameters of electric current and nitrogen gas inlet pressure. The study's novelty arises from the design of a torch for plasma pyrolysis of liquid carbon-based materials, which requires that they must be sprayed into its flame from a specific angle. This study investigated and diagnosed electrical, thermodynamic, and chemical features such as voltage, voltage variations, frequency, type of voltage behavior, thermal efficiency, enthalpy, chemical and atomic species produced in plasma, as well as their excitation and rotational temperature. Results show that the flame's maximum temperature of 3492 K is achievable at 100 A current and 0.5 bar nitrogen gas inlet pressure with an enthalpy of 44.41 MJ kg-1 and thermal efficiency of 75.1% at 20 mm from the nozzle outlet. Comprehensiveness in examining the electrical, thermodynamic, and chemical parameters involved in the constructed plasma torch is another innovation in this study, which sheds light on how to optimize this torch to achieve high-quality results from industrial and experimental points of view.