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

ABSTRACT

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.

KEYWORDS:

• Flour
• inhibitor
• explosion flame
• explosion pressure
• inhibitory mechanism

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [52074174]; Special Project for Benefiting The People of Qingdao West Coast New Area [2020-31].