Application of thermal plasma technology for melting municipal solid waste incineration fly ash: simulation and...

Thermal plasma technology is highly efficient and environmentally friendly for the treatment of municipal solid waste incineration (MSWI) fly ash. However, its high energy consumption hinders its large-scale industrial application. Based on a thermal plasma furnace with a treatment capacity of 5t/d, this study investigated the low energy consumption operating conditions and toxic pollutant removal mechanisms of the thermal plasma furnace treating MSWI fly ash. A three-dimensional Euler-Lagrange multiphase model was established to optimize the operational conditions for thermal plasma treatment of MSWI fly ash. The simulation results indicate that, when the inlet velocity of the MSWI fly ash is 3 m/s, the melt level height remains below 200 mm, and the diameter of MSWI fly ash is approximately 160 μm, the escape rate of the MSWI fly ash is significantly reduced, the corrosion of refractory material is minimized and the melting efficiency of the MSWI fly ash is maximized. These factors collectively contribute to energy savings and a reduction in both operating and post-treatment costs. Experimental validation demonstrates that numerical simulations are highly effective for monitoring the melting of MSWI fly ash in a thermal plasma furnace. Heavy metals leaching experiments and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) concentration distribution showed that heavy metals in the MSWI fly ash were solidified in inert slag resulting in low leaching concentrations, and the PCDD/Fs were dechlorinated and decomposed achieving a removal rate exceeding 99%. These results provide valuable insights for the industrial application of thermal plasma technology in treating MSWI fly ash, aiming to reduce energy consumption, lower costs, and enhance efficiency.