The risks associated with dust explosions still exist in industries that either process or handle combustible dust. This explosion risk could be prevented or mitigated by applying the principle of inherent safety. One effective principle is to add an inert material to a highly combustible material in order to decrease its ignition sensitivity. This paper deals with an experimental investigation of the influence of inert dust on the minimum ignition temperature and the minimum explosion energy of combustible dust. The experiments detailed here were performed in a Godbert–Greenwald (GG) furnace and a 1.2 L Hartmann tube. The combustible dust (polyethylene—PE; 800 mesh) and four inert powders (NaHCO₃, Na₂C₂O₄, KHCO₃, and K₂C₂O₄) were used. The suppression effects of the four inert powders on the minimum ignition temperature and the minimum explosion energy of the PE dust have been evaluated and compared with each other. The results show that all of the four different inert dusts have an effective suppression effect on the minimum ignition temperature and the minimum explosion energy of PE dust. However, the comparison of the results indicates that the suppression effect of bicarbonate dusts is better than that of oxalate dust. For the same kind of bicarbonate dusts, the suppression effects of potassium salt dusts are better than those of the sodium salt. The possible mechanisms for the better suppression effects of bicarbonate dusts and potassium salt dusts have been analyzed here.

The explosion risk of ethylene (C₂H₄) seriously hinders safe development of its production and processing. To reduce the harm caused by C₂H₄ explosion, an experimental study was conducted to assess the explosion inhibition characteristics of KHCO₃ and KH₂PO₄ powders. The experiments were conducted based on the explosion overpressure and flame propagation of the 6.5% C₂H₄-air mixture in a 5 L semi-closed explosion duct. Both the physical and chemical inhibition characteristics of the inhibitors were mechanistically assessed. The results showed that the 6.5% C₂H₄ explosion pressure (P _ex) decreases by increasing the concentration of KHCO₃ or KH₂PO₄ powder. The inhibition effect of KHCO₃ powder on the C₂H₄ system explosion pressure was better than that of the KH₂PO₄ powder under similar concentration conditions. Both powders significantly affected the flame propagation of the C₂H₄ explosion. Compared with KH₂PO₄ powder, KHCO₃ powder had a better inhibition effect on the flame propagation speed, but its ability to reduce the flame luminance was less than KH₂PO₄ powder. Finally, the inhibition mechanism(s) of KHCO₃ and KH₂PO₄ powders were revealed based on the powders' thermal characteristics and gas-phase reaction.

An experiment of inhibition effects by porous media and ultra-fine water mist on stoichiometric methane/air (9.5% methane) explosion was investigated in a semi-confined transparent explosion vessel, which measures 80 × 80 × 1000 mm³. The ultra-fine water mist concentration, porous media porosity factor and pore density were taken into account, and the explosion characteristics such as flame propagation and overpressure were compared and discussed collectively. The results indicated that the tendency of maximum flame propagation speed and maximum explosion overpressure in the upstream of porous media were significantly varied by changing the concentration of ultra-fine water mist, the porosity factor of porous media and the pore size. The porous media placed in the pipeline produced a quenching flame effect, and the addition of ultra-fine water mist reduced the pressure upstream of the porous media significantly. The combination of porous media and ultra-fine water mist existed a coupling inhibitory effect on methane explosion. Compared with pure methane, the time required for tulip flame production was increased. Furthermore, under 87% porosity factor, 20 PPI pore density and 1453.1 g/m³ ultra-fine water mist concentration, the inhibition effect is the most obvious, in which the flame propagation speed was 12.8 m/s, the descending proportion reached 44.23% and the maximum explosion overpressure in the upstream of the porous media was reduced by 40.62%.