Numerical simulation of the dynamic wetting of coal dust by spray droplets

The dust particles generated during coal mining and processing are generally removed by spray dust reduction. The dynamic process via which spray droplets wet and wrap coal dust can directly affect the spray dust reduction efficiency. Here, we analyzed the contact wetting and wrapping process of dust particles by droplets under different particle size ratios and different initial droplet velocities. The results show that the larger the particle size ratio theta of the droplets and dust particles, the greater the variation in the dimensionless spreading coefficient. When the particle size ratio is more than 2, the droplets can completely wrap the coal dust particles. If the initial velocity is too small, the droplets will shrink and return to form a single sheet after coming into contact with the coal dust. With increasing velocity, the dimensionless spreading coefficient increases rapidly, and the coal dust is moistened and rapidly wrapped. By experimenting with various spray atomization characteristics, when the spray pressure is 6 MPa,the droplet size distribution in the spray field accounting for the highest proportion is 10 mu m. Under the optimized parameters, the settling efficiency of respirable dust at each measuring point of mine return air duct reaches 86.2% on average.

Automated summary

The dust particles generated during coal mining and processing are usually removed by spray dust reduction. The contact wetting and wrapping process of dust particles by droplets were analyzed under different particle size ratios and initial droplet velocities. The results showed that the larger the particle size ratio, the more variation in the spreading coefficient. When the particle size ratio was more than 2, the droplets could completely wrap the coal dust particles. The optimized parameters achieved an average settling efficiency of 86.2% for respirable dust in the mine return air duct.