Experimental study and mechanism analysis on the suppression of flour explosion by NaCl and NaHCO3

The suppression effect of adding different proportions of NaCl and NaHCO3 powder on flour explosion was studied by using Hartmann experimental device and 20 L spherical explosive device. The results showed that with the increase of NaCl and NaHCO3 concentrations, the flame speed and propagation distance decreased gradually. The maximum explosion pressure P-max and the maximum pressure rise rate (dP/dt)(max) decreased significantly. When 80% NaCl and NaHCO3 were added, the average flame propagation velocity reduced to 2.73 m/s and 0.56 m/s, respectively, and the maximum explosion pressure less than 0.15MPa, the flour explosion could be inhibited by NaCl and NaHCO3. NaHCO3 was more effective than NaCl in inhibiting flame propagation and explosion overpressure. Finally, combined with the pyrolysis characteristics of NaCl and NaHCO3, the mechanism of inhibitors inhibiting the explosion of flour was further studied. The endothermic decomposition of NaHCO3 produced inert gas, diluted oxygen concentration, captured active free radicals, and terminated the combustion chain reaction. NaCl inhibits the explosion of flour by absorbing heat and coating it.