The inhibiting effects of sodium carbonate on coal dust deflagration based on thermal methods

To aid the development of safe procedures, the inhibiting effects of sodium bicarbonate (NaHCO3) on coal dust explosions were investigated by employing a simultaneous thermal analyzer and a standard 20-L spherical chamber. The thermal behaviors and explosion parameters of the coal dust/NaHCO3 mixtures were characterized and the surface morphology, functional groups and chemical composition of the explosive residue were conducted. Finally, the inhibiting mechanism of NaHCO3 on coal dust explosions was proposed. The results demonstrated that the thermal decomposition temperature of coal dust was increased and the thermal decomposition rate, maximum heat flow, and heat release were decreased after the addition of NaHCO3. The apparent activation energies and pre-exponential factors of coal dust were also increased. The maximum explosion pressure and maximum explosion pressure rising rate during deflagration decrease with an increase in the NaHCO3 mass fraction, and the optimal inhibiting ratio of NaHCO3 powder to pulverized coal explosion is 400%. NaHCO3 powder covers the surface of coal dust particles promoting heat absorption and isolation, and the functional groups, such as C=C, C-O and C-H, are protected by NaHCO3, preventing coal dust pyrolysis and inhibiting the explosions. The results provide guidance for the prevention of coal dust explosion.