Designing a Scaled Erosion Test With Computational Fluid Dynamics Methods

The Department of Energy is sponsoring the River Protection Project, which includes the design of a facility to stabilize liquid radioactive waste that is stored at the Hanford Site. Because of its experience with radioactive waste stabilization, the Savannah River Technology Center of the Westinghouse Savannah River Company is assisting in the development and testing of parts of the waste treatment process. One part of the process is the separation of highly radioactive solids from the liquid wastes by cross-flow ultrafiltration. For the projected forty-year life of the filtration facility, wear will occur from a combination of erosion and corrosion due to the flow of slurries. A scaled cross-flow filter facility will be tested with simulated waste to quantify the wear rate so that an effective maintenance schedule can be developed. This paper discusses the application of computational fluid dynamics (CFD) methods to ensure that the test facility design would capture the erosion phenomena expected in the full-scale cross-flow ultrafiltration facility. An initial literature survey helped identify the principal drivers of erosion for a solids laden fluid. These were the solids content of the working fluid, the regions of recirculation and particle impact with the walls, and the regions of high wall shear. A series of CFD analyses was then designed to characterize slurry-flow profiles, wall shear, and particle impingement distributions in key pipe bends and fittings representative of the plant. Pipe diameters, lengths, the locations of pipefittings, and slurry velocities were scaled with the CFD calculations to ensure that the erosion drivers were appropriately represented in the test facility. This resulted in a validation of the theoretical determination of those drivers, and allowed the test results to be applied to a prediction of wear in the full-scale filtration facility.