Dust Explosion Characteristics of Agglomerated 35 nm and 100 nm Aluminum Particles

Abstract

In the experiment, nanoparticles of 35 nm Al and 100 nm Al powders, respectively, formed particles with average sizes of 161 nm and 167 nm in agglomeration. The characteristics of dust cloud explosions with the two powder sizes, 35 nm and 100 nm, revealed considerable differences, as shown here: (dp/dt)max-35 nm= 1254 bar/s, (dp/dt)max-100 nm= 1105 bar/s; Pmax-35 nm= 7.5 bar, Pmax-100 nm= 12.3 bar, and MEC-35 nm= 40 g/m3, MEC-100 nm= 50 g/m3. The reason of Pmax-35 nmvalue is smaller than Pmax-100 nmmay be due to agglomeration. From an analysis of the explosive residue, the study found that nanoparticles of 35 nm Al powder became filamentous strands after an explosion, where most of 100 nm Al nanoparticles maintained a spherical structure, This may be because the initial melting temperature of 35 nm Al is 435.71°C, while that for 100 nm Al is 523.58°C, higher by 87.87°C. This study discovered that explosive property between the 35 nm Al and 100 nm Al powders after agglomeration were different.

Explosibility of micron- and nano-size titanium powders

“…34 Likewise, Wu et al 35 performed nano-dust explosions in a 20-L chamber using aluminum with average particle sizes of 35 nm and 100 nm, resulting in a P max of 7.3 bar(g) and 12.5 bar(g), and (dP/dt) max of 1286 bar/s and 1090 bar/s, respectively. These results can be compared to larger micron-aluminum powder data obtained from Eckhoff.…”

“…3 Again, agglomeration affects the severity of the explosion and decreases the maximum pressure and maximum rate of pressure rise. 35 Wu et al 36 also tested the minimum ignition energy (MIE) of micron-and nano-titanium.…”

A Study on Explosion Characteristics of Toner Powder

“…The P max of hpQ2612A toner was 0.74 MPa and the (dP/dt) max was 100.5 MPa/s when the dust concentration was 500 g/m 3 . These values were very equal to the agglomerated aluminum particles as P max =0.75Mpa with 35nm and (dP/dt) max =110.5 MPa/s with 100nm [4]. The results indicated that the toner dust explosion was intense and could make biggish damages if the explosion occurred.…”

Nanopowders explosion: Influence of the dispersion characteristics

“…Feedback on accidents involving nanopowders explosions is still rare. However, some accidents involving nanometric powders have already been identified for aluminum in attrition millers (Wu et al, 2010a) or in a Taiwanese laboratory when handling 75 nm titaniumparticles (Wu et al, 2014). As for micron-sized particles, a quantitative risk analysis must be conducted in order to propose appropriate prevention and protection means.…”

“…Several hypotheses have been put forward to explain these observations: i) as the specific surface area increases, nanoparticles tend to agglomerate which reduces the reactive active surface with oxygen and decreases the explosivity (Eckhoff, 2011;Wu et al, 2010a); ii) the evolution of the particle size distribution (PSD) of the nanoparticles impacts the heat transfer phenomena, especially radiative, taking place upstream of the flame front (Dufaud et al, 2011;Kosinski et al, 2013;Sundaram et al, 2013); iii) in the case of metal nanopowders, the passivation of the surface can be enhanced with regard to the microparticles (Eckhoff, 2012;Sundaram et al, 2013); iv) the rate-determining step of the combustion reaction differs from micro to nanopowders (Bouillard et al, 2010); v) flame stretching effects, which can be observed for large non-volatile particles, are unlikely to be observed for pure nanos (Cuervo et al, 2017).…”