Study On The Suppression Characteristics Of Solid State Inhibitors On Coal Dust Explosion

As one of the main energy sources in China,coal dust generated during its mining process,once suspended in the air to form a dust cloud,is ignited by a certain amount of energy,and is extremely prone to hazardous dust explosion accidents.Therefore,researching the impact of solid state inhibitors on suppressing coal dust explosions is of great significance for coal mine safety production.In this paper,lignite coal dust was selected as the research object,and silicon dioxide（Si O₂）,melamine polyphosphate（MPP）,melamine cyanurate acid（MCA）,and ammonium dihydrogen phosphate（NH₄H₂PO₄）were selected as solid inhibitors to study the explosion characteristics of coal dust.Firstly,the characteristic parameters of coal dust explosion and suppression characteristics were discussed by using the dynamic test system of dust explosion flame propagation and the minimum ignition temperature test system of dust;Secondly,the three-dimensional numerical simulation of the coal dust diffusion process in a vertical combustion tube was conducted using ANSYS Fluent software;Finally,the temperature rise decomposition process of inhibitors was analyzed by synchronous thermal analysis technology,and the inhibition mechanisms of four inhibitors were summarized.The specific research contents and results are as follows:（1）The explosion sensitivity parameters of coal dust under different concentrations and injection pressures were studied through experiments.With the increase of concentration,the minimum ignition energy and minimum ignition temperature of coal dust showed a trend of decreasing first and then increasing.When the injection pressure gradually increased,the minimum ignition temperature of coal dust decreased first and then increased.（2）The flame propagation characteristic of coal dust explosion was studied by experimental.When the concentration of coal dust was 500 g/m³,the flame brightness was large,the front was flat,and it s propagated outside the tube to form a typical mushroom cloud flame with a propagation height peak of 0.59 m and propagation velocity peak of 4.68 m/s.（3）The three-dimensional numerical simulation of the coal dust diffusion process in a vertical combustion tube was conducted using ANSYS Fluent software.The variation laws of pressure,air flow rate,turbulent kinetic energy,and particle motion process were analyzed.Combined with experiments,the results showed that when the ignition delay was 70 ms to 90ms,it was beneficial for ignition.（4）The explosion characteristic parameters of mixed dust under different inhibitor types and ratios were experimentally studied.With the increase of the inhibitor ratio,the minimum ignition temperature of the mixed dust continued to increase,and the flame propagation height and velocity decreased significantly.The order of inhibition effect from low to high was Si O₂<MCA<NH₄H₂PO₄<MPP.（5）The thermal characteristics of coal dust and inhibitors in the heating process were analyzed using a thermogravimetric analyzer,and the inhibition mechanisms of the four inhibitors were explored based on the theory.The inhibition effect of Si O₂ on coal dust explosion was manifested as physical inhibition,mainly including absorbing heat and isolating heat and oxygen.MPP,MCA,and NH₄H₂PO₄ had a dual physicochemical inhibiting effect on coal dust explosion,which can not only absorb heat,but also the decomposition products can absorb free radicals in the system to form inert substances,further inhibiting coal dust explosion.