Coal particle transport behavior in a rotating drill pipe used for negative pressure pneumatic conveying

Conveying gas velocity, rotation speed, and particle diameter are all common parameters in a negative pressure pneumatic conveying system that affect the system's energy consumption and design. Herein, the effect of the above three parameters on the transport behavior of coal particles was investigated by coupling Computational Fluid Dynamics and the Discrete Element Method (CFD–DEM) approach. The numerical results indicate that increasing gas velocity increased the number of coal particles entering the drill pipe. An increase in particle velocity increased conveying efficiency. With increasing particle diameter, the number of coal particles entering the drill pipe decreased. The particle velocity decreased, resulting in a decrease in conveying efficiency. In contrast, as the rotation speed increased, the particle distribution within the drill pipe became more dispersed, and the swirling flow trajectory became more apparent. The number of coal particles and conveying efficiency were decreased, although the effect on particle velocity was negligible.