In order to study the inhibition effect of gas–solid two-phase inhibitors on a methane explosion, the influence of these parameters was investigated and compared with that of single-phase inhibitors. The results show that the inhibition effect of gas–solid two-phase inhibitors on a methane explosion is better than the added effect of two single-phase inhibitors, indicating that a synergistic effect can be obtained by gas–solid two-phase inhibitors. The two-phase inhibitors which are composed of NaHCO₃ (BC) powders and inert gas have a better suppressing property than those composed of NH₄H₂PO₄ (ABC) powders and inert gas. The two-phase inhibitors composed of CO₂ and powders have a better suppressing property than those composed of N₂ and powders. The 9.5% premixed methane–air mixture can be completely inhibited by 0.10 g/L BC powders mixed with 8% CO₂. The suppression mechanisms of the gas–solid two-phase inhibitors on the methane explosion were discussed.

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.

In order to investigate the change law of the explosion characteristic parameters of hybrid mixture of coal dust and gas, and then establish an effective prediction method of these parameters, the maximum explosion pressure, explosion index, and lower explosion limit of coal dust and gas mixtures were measured in a standard 20 L spherical explosion system. Four different kinds of hybrid mixture were selected in this study and they are composed of coal dust with different components and gas respectively. According to the measured results, the change law of the explosion characteristic parameters of hybrid mixture of coal dust and gas was analyzed, and the prediction method of these parameters was discussed. The results show that the addition of gas to a coal dust cloud can obviously increase its maximum explosion pressure and explosion index and notably reduce its minimum explosion concentration. On increasing the gas equivalent ratio, the maximum explosion pressure of coal dust and gas mixture increases linearly and the explosion index increases quadratically, while the decrease curve of the lower explosion limit is nonlinear. Based on these change laws, the methods for predicting the maximum explosion pressure and the explosion index of hybrid mixture of coal dust and gas were established respectively. The applicability of the existing methods for predicting the lower explosion limit of hybrid mixture to coal dust and gas mixture was demonstrated.

In this paper, montmorillonite inhibitors modified with polyhydroxy functional groups by gluconic acid (GA) were successfully prepared. The particle size distribution, composition, surface functional groups, and pyrolysis characteristics of the pure montmorillonite powders (Mt) and the gluconic acid modified powders (G-Mt) were analyzed by using a laser particle analyzer, X-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetry–differential scanning calorimetry (TG-DSC), respectively. The suppression effect of Mt and G-Mt on the 9.5% methane–air premixed gas was tested in a 20 L spherical explosion device and a 5 L pipeline experimental system. The results show that G-Mt displays a much better suppression property than that of Mt. The optimal explosion suppression effect concentration of Mt or G-Mt powders is about 0.25 g·L⁻¹. In this concentration, for G-Mt, the maximum explosion pressure declined by 26.7%, the maximum rate of pressure rise declined by 74.63%, and the time for the flame front to reach the top of the pipe was delayed by 242.5%. On the basis of the experimental data, the better suppression effect of G-Mt than Mt might be attributed to the presence of more hydroxyl groups on the surface.