Effect of monoammonium phosphate particle size on flame propagation of aluminum dust cloud

摘要

The effect of monoammonium phosphate (NH4H2PO4) particles on 5 um aluminum dust flames is investigated experimentally and computationally. NH4H2PO4 in three particle size is employed to determine the inhibition efficiency on aluminum flame propagation. Flame inhibition mechanism considering both gas and surface chemistry of aluminum particles is developed. Results show that the inhibition effectiveness monotonously increases as NH4H2PO4 particle size is reduced to 25 pm. Flame morphology and flame microstructure change with the addition of different particle size NH4H2PO4. Small NH4H2PO4 particles within the range studied have a greater reduction in average flame propagation compared to the coarser one. Meanwhile, the fine NH4H2PO4 particles almost decompose completely during the penetration of aluminum flame and then undergo a sufficient chemical interaction with the flame. The simulations indicate that the decomposition products of NH4H2PO4 particles obstruct the oxidation of aluminum particles through flame radical consumption. Additionally, the addition of NH4H2PO4 can reduce the vaporization rate and surface reaction rate of aluminum particles.