Effects of dust concentration, particle size, and crude oil concentration on the explosion characteristics of oil-immersed coal dust

To investigate the explosion hazards of oil-immersed coal dust in co-existing mine areas, the explosion characteristic parameters of coal dust under different particle dimensions, coal dust concentration, and oil-immersed concentration were studied in a 20-L explosion chamber. The maximum explosion pressure of oil-immersed coal dust first decreases and then increases as coal dust particle size increases. For oil-immersed concentration samples between 2 and10 wt.%, the Kst value, and maximum explosion pressure of the oil-immersed samples were higher than those of the raw coal counterpart. The maximum explosion pressure of oil-immersed samples was 7.49%, 4.10%, 5.7%, 7.13%, and 4.10% higher than the raw samples. Moreover, when the oil-immersed concentration was 6 wt%, the minimum explosion concentration (MEC) of finer particles was the lowest, while the MEC for large particles was the highest. The impact mechanism of coal dust concentration on maximum explosion pressure is that the number of coal dust particles affects the distance between particles and heat transfer efficiency. The influence mechanism of particle size on the explosion of oil-immersed coal is that the particle size can reflect the specific surface area size, which affects the diffusion of oxygen in particles and the rate of combustible volatiles released by particles. Hydrocarbons released from the crude oil via heating and the complex organic molecules generated during high-temperature pyrolysis produced simpler hydrocarbons, generating hydrogen and higher temperatures that accelerated the onset of explosions and increased coal dust explosion intensity. These experimental results were of use to process safety working and can help prevent coal dust explosion accidents in underground coal mines.

Automated summary

This study investigated the explosion hazards of oil-immersed coal dust in co-existing mine areas through experimental research. The results show that the maximum explosion pressure of oil-immersed coal dust first decreases and then increases as the coal dust particle size increases. For samples with oil-immersed concentrations between 2% and 10%, the explosion characteristic parameters were higher than those of the raw coal counterpart. The influence mechanism of coal dust concentration on maximum explosion pressure is that the number of coal dust particles affects the distance between particles and heat transfer efficiency, while the influence mechanism of particle size is that it affects the diffusion of oxygen in particles and the rate of combustible volatiles released by particles.