(348h) Segregation Effects in Three Types of Mass Flow Hoppers

Mass flow is often suggested as a means of solving all segregation issues. However, although traditional mass flow may be a necessary condition to solve several segregation issues, it is not a sufficient condition. The solution to segregation in process equipment requires matching the segregation pattern and magnitude to the velocity profile in the specific mass flow bin or hopper. Many mass flow hoppers produce flow along the walls. However, not all of these designs are sufficient to mitigate segregation. This paper addresses segregation prevention in typical conical hoppers, cone-in-cone hoppers, and Diamondback® or plane flow hoppers. All of these bins can be designed as mass flow devices. Nonetheless, because of differences in velocity profiles in each of these bins, they offer differences in the ability to mitigate segregation. The focus of this paper is to compare the segregation prevention of using these three types of mass flow bins with radial segregation patterns as well as axial segregation patterns. The radial stress theory was used to compute velocities in the bin. These velocities were then used to estimate the expected segregation mitigation for radial as well as axial segregation patterns. Six conditions were compared. These include conical hoppers, cone-in-cone hoppers, and Diamondback® hoppers. In each case, the effect of both radial and axial segregation patterns were examined. In each case, segregation mitigation plots were generated and compared to determine which hopper configurations yielded the best segregation prevention.