Abatement of volatile organic compounds (VOCs) and fluorine gases by a microwave plasma torch (MPT)

The use of microwave plasma torch (MPT) in the abatement of potent greenhouse and fluorinated (F-gases) gases is crucial due to their high global warming potential. The purpose of this study was the abatement of volatile organic compounds (VOCs) and carbon tetrafluoride (CF4) using specifically designed reverse vortex flow reactor (RVR) and pillar of fire reactor (POF). The RVR has properties that are crucial for their synergistic effects with the MPT, and the POF configurations showed high-efficiency combustion due to plasma radicals and a large contact area with the MPT. The study used Aspen Plus and COMSOL software to analyse the mass balance involved in the thermal decomposition of isopropyl alcohol (C₃H₈O) and CF₄ and to design the RVR and POF reactors. Using MPT without hydrocarbon fuel, low-concentration C₃H₈O and CF₄ were successfully destroyed in high-flow streams. The experiment on C₃H₈O showed that using a plasma power of 2 kW and 1 cubic meter per minute (CMM) of bulk gas, a destruction removal efficiency (DRE) of 95 % was achieved for a polluted C₃H₈O of 410 ppm. In a second experiment, a DRE of 94 % was achieved for a polluted C₃H₈O of 370 ppm. The first CF₄ experiment achieved a DRE of 93.3 % with a 7 kW plasma power and 1 CMM bulk gas polluted at 285 ppm. In the second experiment, the presence of highly reactive hydroxyl radicals (OH*) in steam plasma improved the DRE to 99.8 % at 7 kW plasma power and 100 LPM bulk polluted at 180 ppm.