SSL - Settling Slurry

What is the SSL Module?

An optional add-on module to AFT Fathom which allows users to simulate settling slurries.

Settling slurries are fluids which carry solids of relatively large size which cannot be suspended in the liquid under all conditions. At sufficiently low velocities the solid particles will settle to the bottom of the pipe and may ultimately plug the pipe completely. It is important to predict the behavior of such flows to avoid settling conditions and economically move the fluid and solids through the pipe.

The SSL module allows users to predict the behavior of settling slurries within the framework of the powerful AFT Fathom software. The SSL module allows users to specify solid particle properties, distribution and concentration. State-of-the-art correlations are then used to predict the flow, pressure drop and reduced pump performance when pumping solids.

Special output reports and system curve generation are available to assist the user with understanding the hydraulic behavior of the slurry.

The SSL module can work in conjunction with the other AFT Fathom modules. The XTS module allows users to model slurry flows of constant concentration which vary over time. The GSC module allows users to vary input parameters automatically to achieve desired output parameters.

How Does the SSL Module Work?

The SSL module offers additional input windows where users can enter the properties of the solid particles. The SSL module takes the properties of the solid particles and carrier fluid (which is often water but can be another fluid) and calculates the hydraulics of the piping and pumps using widely accepted correlations.

Predicting the flow of settling slurries depends heavily on correlations based on experiment. Such predictions are inherently less accurate than standard clear fluid pipe flow.

Using the SSL Module

The user has the option of activating or not activating the SSL module when AFT Fathom first loads. After AFT Fathom is loaded, the SSL module can be activated or deactivated for use from the Modules panel in the Analysis Setup window or the Tools menu. Whether or not SSL is activated impacts the Analysis menu, Library menu and Output window as is discussed in the Modules panel topic.

If the SSL module is active, the user can still run models without slurries. This is selected under Slurry Modeling on the Analysis menu. Hence there are three possibilities for the SSL module.

  • SSL is not active

  • SSL is active and slurry calculation is disabled

  • SSL is active and settling slurry calculation is performed