Novel three-phase steam–air plasma torch for gasification of high-caloric waste

Research results are presented for an AC electric arc that burns a mixture of steam and air in a three-phase high-voltage plasma torch and can be implemented to produce plasma for plastic waste gasification. The dependences of electric parameters on the ratio of the steam to air mass flows (H2O/air ∼1–6) at an approximately constant total mass flow of the plasma-forming gas are obtained during several experiments. During the experiments, the arc parameters were as follows: voltage drop of 1.0–1.8kV, current of ∼28.5A and power of ∼52–86kW. The thermal efficiency of the plasma torch was ∼94–95%. CCD cameras operating at 4000fps were used to determine the average discharge length of ∼798mm. Photography with a high shutter speed (1/8000s) was used to determine the average arc diameter (∼4.47mm). Arc temperatures were calculated (10,000–11,500K) using the thermodynamic equilibrium approach. Experimental results indicate that increases in the steam content of the steam–air plasma lead to a reduction of the arc’s temperature and electrical conductivity. Using an equilibrium approach, the main parameters of plasma gasification were estimated: syngas yield (3.62–3.48m3/kg), composition (H2 – 55.5–62.5, CO – 32.8–34.1vol.%) and energy consumption (11.0–12.3MJ/kg).