Experimental investigation and molecular reaction mechanism of methane/powdered coal deflagrations inhibited by neosynthetic fly-ash inhibitors

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This study probes the macroscopic characteristics and microscopic mechanism of novel synthetic fly-ash-containing modified deflagration inhibitors in inhibiting methane/powdered coal deflagrations. The microscopic properties of the raw samples and post-deflagration residues were comparatively analyzed based on the macroscopic deflagration tests. Additionally, the inhibition mechanisms of fly ash loaded with nitrogenous-containing compounds (MFAC) and fly ash loaded with nitrogen- and phosphorus-containing compounds (PMFAC) in methane/powdered coal deflagration were microscopically interpreted using quantum chemical simulations. The results indicated that MFAC exhibited a weak inhibitory effect but a strong promoting effect when the concentration reached 50 g/m³; it exhibited a strong inhibitory effect when the concentration exceeded 100 g/m³. PMFAC demonstrated a stronger inhibitory effect with increasing concentration, especially in inhibiting the flame behavior and pressure parameters. Moreover, the analysis of post-deflagration residues revealed that PMFAC effectively inhibited the deflagration chemical reactions involved in methane/powdered coal and the as-obtained products. Furthermore, during the deflagration, MFAC primarily absorbed reactive free radicals (•H/•O/•OH) via the amino groups, whereas PMFAC was additionally attacked by phosphorus-containing groups, which functioned as electrophilic sites. Finally, MFAC and PMFAC exerted a cold-wall effect on flame propagation, hindered the production of active radicals, and terminated the propagation of chain reactions involved in methane/powdered coal deflagrations.