Experimental study on using water mist containing potassium compounds to suppress methane/air explosions.

To understand the suppression effects of different potassium compounds on methane/air explosions, a 20-L spherical explosion system and a high-speed camera were used to obtain the explosion overpressure and the flame morphology for explosions at different methane concentrations under the action of solutions of five potassium compounds (for the same experimental conditions). The effects of the different additives on the maximum explosion overpressure Pmax, the maximum rate of increase in the overpressure (dp/dt)max, the time to reach the maximum overpressure tPmax, the deflagration index KG and the flame morphology were compared and analyzed. The results indicate that the potassium compounds possessed a relatively strong capability to suppress explosions of nonstoichiometric methane mixtures. Compared with the stoichiometric condition, in 7.5 % and 11.5 % methane/air explosions, there were substantial decreases in Pmax, (dp/dt)max, and KG under the action of the same potassium compounds, meanwhile, tPmax increased considerably, and the maximum overpressure reduction rate reached 20.6 %. Of the five potassium compounds, potassium oxalate had the strongest suppression ability. The strength of the suppression effect by the potassium compounds on the methane/air explosions increased in the following order: potassium dihydrogen phosphate < potassium chloride < potassium acetate < potassium carbonate < potassium oxalate.