Continuous supercritical hydrothermal combustion experimental and burner structure optimization simulation study

Supercritical hydrothermal combustion is the rapid exothermic oxidation reaction occurring in supercritical water, which can be utilized in the treatment of high-concentration organic wastewaters. In this study, preliminary ignition experiments of continuous hydrothermal combustion are conducted. It is found that using hydrogen peroxide as oxidant can decrease the ignition temperature, but recirculation zone cannot be established due to the increase in the momentum ratio between oxidant and fuel. Furthermore, the coaxial-jet and jet-in-crossflow combustors are simulated to investigate the effect of geometry on the flame characteristics. For the coaxial-jet configuration, the moderate increase in recirculation zone can improve the flame stability, and the optimized Craya-Curtet number is around 0.17. For the jet-in-crossflow configuration, the oxygen-rich recirculation zone is more liable to accumulate heat than the fuel-rich one, and hence it does more favors for the flame stability. A new jet-in-crossflow combustor with oxygen as the core jet is proposed and demonstrates to be able to decrease the extinction temperature by ∼100 K lower than the existing devices.