Suppression of pulverized biomass dust explosion by NaHCO3 and NH4H2PO4

Abstract

To effectively mitigate accidental biomass dust explosion, the suppression capacities of NaHCO3 and NH4H2PO4 for biomass dust explosion were determined. Suppression mechanism of biomass flame was further revealed. Poplar sawdust and peanut shell dust with two particle size distributions were employed. A high-speed camera was used for to capture flame propagation behavior and microstructure. Flame temperature was measured by a fine thermocouple. Results showed that the consequences of poplar sawdust explosion are greater than peanut shell dust. By increasing the concentration of NaHCO3 and NH4H2PO4, the average flame velocity and flame temperature of pulverized biomass dust were significantly decreased. The minimum suppression concentration of NaHCO3 was about 30% lower than that of NH4H2PO4. The suppressants could consume key radicals of biomass flame, resulting in lower flame speed and lower flame temperature. The heat absorbed by NH4H2PO4 decomposition was about 6.5 times that of NaHCO3 decomposition. However, the extra heat released from the exothermic reactions of NH4H2PO4 could enhance biomass combustion. Hence, NaHCO3 has a better suppression performance than NH4H2PO4 for biomass dust explosion.