Flow regime transition and hydrodynamics of spouted beds with binary mixtures

• A stable spouting range is broadened in spouted beds of binary mixtures.
• Ums and Hms increase with increasing large particle size and particle density.
• The Ums is also found to relate to the particle properties and mixing degree.
• Increased particle difference leads to poor mixing or even segregation.

The spouting of fine particles is significantly different from that of coarse particles and a stable spouting can only be obtained under very constrained operating conditions. However, the stability of a spouted bed with fine particles can be effectively improved by addition of coarse particles. In this work, the flow regime transition and hydrodynamics of spouted beds with binary mixtures were experimentally investigated under a broad range of operating parameters. Effects of particle size, density, mixing ratio, gas velocity and nozzle diameter on flow regime transition and minimum spouting velocity in spouted beds were explored. The results show that a moderate increase in the mean particle diameter and density due to addition of coarse particles is beneficial to spouting stability. However, segregation is also observed when adding excess amount of coarse particles, thus leading to decreased spouting stability.

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