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 NaHCO 3 (BC) powders and inert gas have a better suppressing property than those composed of NH 4 H 2 PO 4 (ABC) powders and inert gas. The two-phase inhibitors composed of CO 2 and powders have a better suppressing property than those composed of N 2 and powders. The 9.5% premixed methane-air mixture can be completely inhibited by 0.10 g/L BC powders mixed with 8% CO 2 . The suppression mechanisms of the gas-solid two-phase inhibitors on the methane explosion were discussed.Energies 2019, 12, 398 2 of 10 Chemical powders, such as carbonate, phosphate, halide etc., have widely been used as extinguishing agents on methane explosions and dust explosions, due to their physical and chemical inhibition effects. The inhibition effects of various chemical powders (such as SiO 2 , CaCO 3 , ABC, BC, zeolite, red mud, Al(OH) 3 , composite powders, etc.) on methane explosions have been studied [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The experimental results presented that different powders showed different suppression performances on methane explosions.Recently, more attentions have been paid to gas-solid two-phase inhibitors [27][28][29]. Deng [30] studied the influence of a two-phase inhibitor Mg(OH) 2 /CO 2 on methane explosion, and observed that the actual superposition effect was inferior to the theoretical superposition effect. The research by Luo [31] showed that the ABC/CO 2 two-phase inhibitor had a cooperative synergism, which gave a good suppression performance on methane explosion. Jiang [32] researched the suppression effect of ultrafine ABC powders and N 2 mixture on methane explosions. The results showed that the maximum decreasing amplitudes of the overpressure and the flame speed were 76.8% and 100%, respectively. According to the research, it is clear that the suppression effect of gas-solid two-phase inhibitors was better than the single-phase gases or powders. However, there are few studies comparing the actual suppression effect of gas-solid two-phase inhibitors with the theoretical addition effect suppressed by single-phase gas and powders, respectively. It is not clear whether there is a cooperative effect between inert gas and powders.In this paper, the influence of ABC powders (NH 4 H 2 PO 4 ), BC powders (NaHCO 3 ), N 2 , CO 2 and gas-solid two-phase inhibitors on the 9.5% premixed methane-air explosion parameters, including the max-pressure, the time to max-pressure and the maximum rate of pressure rise, was experimentally researched using a 20 L spherical vessel. The actual suppre...

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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.

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.

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