Study on the suppression of hydrogen-air explosions by ultrafine water mist containing KCl, K2CO3, or NaCl

Abstract

Hydrogen explosions pose significant risks in industrial applications due to their highly reactive and flammable nature. While most existing studies have focused on water mist (WM) with additives to suppress deflagrations in hydrocarbon combustion, research on hydrogen explosions remains limited. This work aims to address these gaps by investigating the effects of different WM concentrations (600 g/m³-2400 g/m³), alkali metal salt additives (KCl, K₂CO₃, NaCl), and alkali metal salt concentrations (2.5%, 5%, and 7.5%) on hydrogen explosions across varying hydrogen concentrations (20%–40%) in a vented vessel. Key findings reveal that 5% KCl mist exhibits a better suppression efficiency. Increased mist concentration effectively reduces both flame propagation velocity and explosion pressure. When the hydrogen concentrations are 20% and 35%, with a 5% KCl mist concentration of 2400 g/m³, the maximum explosion overpressure decreased by 60.48% and 40.02% respectively, compared to no suppressant. The suppression mechanism was inferred to involve a combination of physical effects (heat absorption and dilution) and chemical interactions (formation of KOH). These results provide valuable insights into optimizing explosion suppression strategies for hydrogen explosions in the process industry.