(137d) Riser-Flow Measurements of Polydisperse Geldart Group B Particles

Flows involving solid particles are used extensively in industry including areas such as pollution control, pharmaceuticals, energy production, and materials synthesis. However, a predictive understanding of polydispersity in riser flows, particularly for continuous size distributions, has not been established. This work is part of an overall aim to develop validated, continuum models for polydisperse, gas-solid systems using a combination of theory, simulations, and experiments. The focus of this effort is to generate a comprehensive experimental dataset that will provide a testing ground for first-principle models. Experiments involving Geldart Group B particles with a continuous size distribution have been carried out over a range of parameters: superficial gas velocity, overall solids flux, and various distribution widths. Measurements include pressure drop, solid concentration, solid flux, solid velocity and segregation. The results here expand on the previous findings of Karri and Knowlton (1998) at lower velocity, which showed (i) radial size-segregation was observed only in downflow annulus and not upflow annulus, and (ii) the lack of axial size-segregation. Surprisingly, at the higher velocities in this work, both axial and radial size-segregation was observed for both upflow and downflow annulus.

Reference:

Karri, S.B. and T.M. Knowlton, "Flow direction and size segregation of annulus solids in a riser," Fluidization IX, Durango, CO (1998).