Effect of Stearic Acid Coating on the Explosion Characteristics of Aluminum Dust

Abstract

To explore the effect of stearic acid coating on the explosion characteristics of aluminum dust, the flame propagation characteristics, minimum explosion concentration and explosion overpressure characteristics of aluminum (Al) and stearic acid coated aluminum dust (SA-Al) were studied by using the synchronous thermal analyzer, improved Hartmann tube explosion test device, and 20 L explosion test device. Then micro morphology and composition of the explosion products were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and a physical model of stearic acid coated aluminum dust explosion was established. The results show that the combustion intensity and flame propagation velocity of SA-Al dust in the semi-closed pipe are lower than that of Al dust, and the flame propagation is weak in the initial stage of explosion. The minimum explosion concentration (MEC), the optimal explosion concentration, the maximum explosion pressure P_max and the maximum explosion pressure rise rate (dP/dt)_max of SA-Al dust are greater than that of Al dust, and its products contain the incomplete combustion products AlO₂, indicating that the stearic acid coating can abate the explosion sensitivity of Al dust, and weaken the degree of oxidation of Al dust. In case of explosion, stearic acid coating can significantly enhance the explosion hazard of Al dust, resulting in a higher explosion risk.

Keywords: dust explosion, stearic acid coated aluminum dust, aluminum dust, pyrolytic oxidation, Explosion characteristics