Riser hydrodynamic study with different Group B powders

Experiments were conducted in a large cold flow CFB unit (18 m long riser and 30 cm in diameter) with three Group B powders. Sand, glass beads and a metal ore, with similar particle size, were used to study the impact of particle density and sphericity. The impact of particle nature on the riser hydrodynamics was investigated at similar operating conditions. Resulting axial pressure profiles are very different in both the acceleration and the fully developed region. These differences can most probably be explained by the difference in shape between the solids. Higher sphericity seems to generate less pressure drop and smaller values of drag force. The influence of particle shape on acceleration resulting fromgas–solidmomentumtransfer and the impact on particle concentration in the fully developed region are then studied. To analyze the results, amonodimensionalmomentumbalance study was conducted, resulting in a new formulation for the average drag force, based on experimental results.

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