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Flame Inhibition by Potassium-Containing Compounds



Valeri I. Babushok, Gregory T. Linteris, Pol Hoorelbeke


A kinetic model of inhibition by the potassium containing compound potassium bicarbonate is suggested. The model is based on the previous work concerning kinetic studies of suppression of secondary flashes, inhibition by alkali metals and the studies of emission of sulfates and chlorides during biomass combustion in the presence of potassium. Kinetic model includes reactions with the following gas-phase potassium-containing species: K, KO, KO2, KO3, KH, KOH, K2O, K2O2, K2O2H2, K2CO3, KHCO3 and KCO3. Flame equilibrium calculations demonstrate that the main potassium-containing species in the combustion products are K and KOH. The main inhibition reactions, which comprise the radical termination inhibition cycle are KOH+H=K+H2O and K+OH+M=KOH+M with the overall termination effect: H+OH=H2O. Numerically predicted burning velocities for stoichiometric methane/air flames with added KHCO3 demonstrate reasonable agreement with available experimental data. A strong saturation effect is observed for potassium compounds: approximately 0.1% of KHCO3 is required to decrease burning velocity by a factor of 2, however an additional 0.6% is required to reach a burning velocity of 5 cm/s. Analysis of the calculation results indicates that addition of the potassium compound quickly reduces the radical super-equilibrium down to equilibrium levels, so that further addition of the potassium compound has little effect on the flame radicals.
Combustion Science and Technology


potassium-containing fire suppressant, potassium bicarbonate, flame inhibition, kinetic model, saturation effect


Babushok, V. , Linteris, G. and Hoorelbeke, P. (2017), Flame Inhibition by Potassium-Containing Compounds, Combustion Science and Technology, [online], (Accessed May 20, 2024)


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Created June 30, 2017, Updated November 10, 2018