Solving Slurry Valve Erosion Problems Using Multiphase CFD Analysis

Digital simulation and analysis of fluid flows (CFD) is the tool of choice for many problems involving fluid mechanics, heat transfer, or chemical reaction performance. It is often infeasible to capture all of the relevant physics experimentally within typical cost and time constraints and physical measurements often do not give a complete picture of why a particular design does or does not work.

The highly detailed results of a CFD simulation allow visualization of flow patterns in even the most inaccessible locations of a complex flow system. Understanding the characteristics of fluid flows associated with a product or process can give tremendous insight into improving product or process performance, troubleshooting existing problems, and provide significant opportunity for cost-cutting and innovation.

In one case, an alumina refinery in Texas was experiencing routine failures of globe valves located in a slurry pipeline. Operating conditions within the plant are particularly harsh since the slurries involved are highly abrasive. Good fluid flow design in the piping systems requires uniform flow with minimum fluid recirculation zones and flow separation.

A typical wear problem involved a slurry pipeline system in which a large diameter globe valve was experiencing a high erosion rate in the seat area. The stellite hard face was experiencing high erosion rates which resulted in leakage through the seat.  Every two weeks the valve would begin to leak requiring expensive downtime and repair of the seat surface.

Goyne Consulting developed a multi-phase CFD model of the flow of liquid (caustic) and solids (mud + sand) particles in the process line.  The CFD model revealed a vortex forming in the valve immediately downstream of the raised disc. This resulted in high velocities, wall shear, and high rates of particle impingement. Subsequent modeling by Goyne identified a solution by rerouting the pipeline which eliminated the vortex.

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