- 4:55 PM

Experimental Investigation and Cfd Modeling of Liquid-Solid Flow with Particle-Particle Collisions

Mark Pepple, Caner Yurteri, and Jennifer S. Curtis. Chemical Engineering, University of Florida, Gainesville, FL 32611

Operations involving solid-liquid flows play a significant role throughout many industries, including pharmaceutical manufacturing, mining, and oil refining. Unfortunately, the limited understanding of solid-liquid systems results in significant loss in productivity. The development of accurate models that predict the behavior of these solid-liquid systems is needed to improve their design, scale up, and optimization. Non-intrusive flow measurements, where multiple flow variables are measured simultaneously are needed to build accurate computer models.

The transition from flow dominated by particle collisions to flow dominated by fluid-particle shear was investigated. Laser Doppler velocimetry (LDV) was used to collect non-intrusive data of the mean and fluctuating velocities of both the solid and liquid components of a turbulent two-phase vertical flow. The velocity and solids concentration of the slurry were varied so that data extended from a collision dominated flow regime to a viscous dominated flow regime. Water and 1 mm soda lime (glass) particles were used and solids concentrations between 0 and 4 percent by volume were investigated over a range of flow velocities. A pilot-scale flow loop made of 3 stainless steel pipe, including a vertical test section 60 diameters in height was constructed. The loop was operated at flows of 100 to 600 gpm.

The data collected was used to validate an Eularian-Eularian based two-phase flow model. In this model, the two-phase system is described by mass and momentum balances for each phase and a fluctuating energy balance for the particle assembly. The results show the transition from viscous dominated to collision dominated flow as a function of solids concentration and flow velocity. Additionally, the results indicate the importance of the coefficient of restitution as a function of the particle-particle impact velocity in accurately predicting the fluctuating solids velocity.