Study of influencing factors of performance in novel vertical roller mills

Abstract

To optimize the particle motion characteristics in a Vertical Roller Mill (VRM), this study proposes incorporating spiral blades to the outer walls of the ash bucket and the outside of the separator. This design utilizes the space between the ash bucket, separator, middle shell, and upper shell to create specific channels for discharging particles outside the mill. The study employs computational fluid dynamics and powder classification methods to perform a comprehensive numerical analysis of the new VRM. By evaluating the flow field distribution, particle motion characteristics, and utilizing the Q criterion, the research identifies three critical parameters that improve the mill's performance: the width, angle, and number of spiral blades. Numerical analysis results reveal that as the width of the spiral blades increases, both the airflow trajectory and flow field distribution improve, thereby facilitating particle transport. When the angle of the spiral blades decreases, the airflow trajectory aligns more closely with the rotation direction of the blades, which is more conducive to discharging particles from the VRM. Furthermore, as the number of spiral blades increases, the airflow velocity within the spiral channel rises, leading to enhanced particle motion characteristics affected by the fluid. When the spiral blades are fully enclosed, with two turns and eight blades, the vortex distribution becomes more regular and the flow field stabilizes, which reduces unnecessary material recirculation. This study provides valuable guidance for optimizing the structure of the VRM and offers references for improving its internal flow fields, enhancing separation performance, and reducing energy consumption.