A comparative study of air and nitrogen thermal plasmas for PFCs decomposition

Abstract Air and nitrogen thermal plasmas were generated from a plasma torch with hollow electrodes to abate CF 4 which is a serious non-degradable greenhouse gas exhausted from the semiconductor manufacturing process. Numerical analysis and experimental demonstration have been carried out to compare effects of plasma forming gas on the decomposition process at the same electric input power of 60 kW and waste gas flow rate of 200 L/min. Higher temperature and longer residence time were expected in nitrogen thermal plasma than air thermal plasma, because relatively low flow rate of nitrogen plasma gas is required at fixed input power compared with air plasma gas. Although small quantity of NF 3 was produced in nitrogen thermal plasma process with hydrogen reactant gas, high destruction and removal efficiency of 99.6% was achievable along with suppression of unwanted NOx generation.