295 / 2018-05-01 22:30:29

Numerical investigation on the dispersion characteristics and explosion process of coal dust cloud in a vertical pipeline

coal dust explosion; ignition delay; turbulence characteristics; dust cloud concentration; flame structure

矿山职业健康与环境安全 > 防尘毒

In order to reveal the temporal and spatial distribution of coal dust dispersion and evolution characteristics of the whole explosion process in a mini space, the physical and mathematical models for dust diffusion and explosion in a vertical pipeline were constructed. Based on the theory of fluid mechanics, FLUENT was applied to simulated the coal dust dispersion characteristics and explosion process using the vertical pipe. The stages of diffusion characteristics of coal dust in vertical pipelines were analyzed and divided. Besides, the influence of particle size and concentration of coal dust on the diffusion characteristic stages was analyzed, and the evolution mechanism of flow field and temperature field in coal dust explosion process in vertical pipeline was revealed. The results showed that: coal dust diffusion in the vertical pipe can be divided into four stages: the fast injection, decelerated dispersion, stability and sedimentation, moreover, the dust concentration and particle size have great influence on the the dispersion process. Simulation results on coal dust explosion have a sound consistency, explosion temperature with the and experimental data. During the whole explosion process, the the flame structure is irregular, and the pressure field increases gradually to the peak and remains stable thereafter. The error about flame height between experimental value and simulation value was less than 5%, while the flame propagation velocity reached its peak at 20 ms and vibrated after 50 ms, particle phase decreased gradually in the whole process, and the particle radiation velocity has randomness, the peak velocity was about 50 m/s. The research results provide a theoretical basis for the foundation and explosion suppression of coal dust explosion.