Analysis of gas—solid coupling flow field in a vertical roller mill under different gas fluxes

Abstract

To understand the powder transportation in HRM4800 vertical roller mill, the mixture multi-phase flow model and the Reynolds stress equation vortex viscosity model were employed to simulate the internal special multi-phase flow of the chamber. The gas flux effect on the gas—solid coupling flow field is also considered in this study. The results show that there is a strong three-dimensional rotation flow field in the powder transportation due to the rotation of the table and rollers. Significant turbulent vortexes in the table—roller flow field have been observed and that field is the main gas—solid coupling flow field of the vertical roller mill. With the increase of gas flux, there is a visible increase of velocity and pressure drop in the multi-phase flow field resulting in improved powder transportation. The phenomena of turbulent pulsation and vortexes under different gas fluxes show that there are restriction problems in the approach of enhancing the efficiency of the vertical roller mill through the increase of gas flux. The studies of gas—solid flow velocity and pressure indicate that there are random characters in the process of turbulent parameters' change and transfer. The results indicate that the structure of the chamber flow model has great influence on the gas—powder flow field, and the optimization design of the vertical roller mill could be achieved with further research work.