Effects of fire extinguishing agents on pyrolysis and explosion characteristics of optical brightener dust

Abstract

As a widely used optical additive, optical brightener has a potential risk of dust explosion during production and utilization, which limits its further application. In this paper, the pyrolysis process and explosion characteristics of universal optical brightener OBA-184 dust were studied, and the inhibition effects of NH4H2PO4, NaHCO3, and aerosil (nano-silica) were compared using the Hartmann tube and the 20-L spherical explosion system. The results illustrate that OBA-184 dust is a substance with huge heat of decomposition. All three extinguishing agents can effectively moderate the ignition sensitivity and explosion severity. Among them, NH4H2PO4 has the best efficiency in suppressing explosion severity due to its excellent chemical inhibition effect. The complete inert ratio of NH4H2PO4 was about 60% lower than that of NaHCO3, while aerosil can not completely inert the OBA-184 dust at the inert ratio in the range studied. NaHCO3 can significantly reduce the ignition sensitivity of OBA-184 dust, and adding 60% NaHCO3 can reduce the dust to a low sensitivity level. Inerting is accomplished due to its low decomposition temperature and violent heat absorption rate; Aerosil is less effective than NH4H2PO4 and NaHCO3, which attributes to its poor physical heat absorption and weak chemical inhibition ability. The results of this paper provide a theoretical and practical basis for dust explosion prevention and control in the optical brightener industry.