This example demonstrates the fundamental concepts of the Settling Slurry (SSL) add-on module by way of example. The example shows how SSL can be used to size a slurry pump as part of a system design process.
The piping for a slurry system that moves sand is being designed. The system will pump 25% sand by volume from an open supply vessel with a liquid surface elevation of 5 feet to an open receiving tank with a liquid surface elevation of 10 feet.
Use the SSL module to size the pump.
Open Analysis Setup from the toolbar or from the Analysis menu. Navigate to the Modules panel. For this example, check the box next to Activate SSL and select Settling to enable the SSL module for use. The items in the Fluid Properties group will change to accommodate slurry definitions. Click OK to save the changes and exit Analysis Setup. Open the Analysis menu to see the new option called Slurry. From here you can quickly toggle between Disable mode (normal AFT Fathom)and Settling (SSL mode).
Open Analysis Setup from the toolbar or from the Analysis menu and input the following on the respective panels.
Carrier Fluid
Fluid Model = Basic (Water)
Temperature = 70 deg. F
Solids Definition
Slurry Calculation Method = Detailed
Solids Specifications = User Specified Solids Added
M (Stratification Ratio Exponent) = Calculated
Terminal Velocity Parameter = Vt / Vts (Xi)
Value = 1
Density = 2.9 S.G. water
d50 = 0.015 inches
d85 = 0.03 inches
Slurry Definition
Slurry Calculation Method = Detailed (this selection will be the same as on the Solids Definition panel)
Concentration Type = Volume Fraction
Amount Solids Added = 25 Percent
Name Alias = Water slurry
At this point, the first two groups are completed in Analysis Setup. The next undefined group is the Pipes and Junctions group. To define this group, the model needs to be assembled with all pipes and junctions fully defined. Click OK to save and exit Analysis Setup then assemble the model on the workspace as shown in the figure below.
Enter the following pipe and junction properties.
All Pipes
Pipe Material = Steel - ANSI
Pipe Geometry = Cylindrical Pipe
Size = 12 inch
Type = STD
Friction Model Data Set = Standard
Length =
J1 Reservoir
Name = Supply Tank
Liquid Surface Elevation = 5 feet
Liquid Surface Pressure = 10 psig
Pipe Depth = 5 feet
J2 Pump
Inlet Elevation = 0 feet
Pump Model = Centrifugal (Rotodynamic)
Analysis Type = Sizing
Parameter = Mass Flow Rate
Fixed Flow Rate = 1400 ton/hr Solids
De-Rating Method = ANSI/HI Standard 12.1-12.6-2016
Percent Fines = 0 %
Head De-Rating Data = Specify Impeller Size Directly
Impeller Size = 8 inches
J3 Elbow
Inlet Elevation = 0 feet
Type = Standard Elbow (knee, threaded)
Angle = 90 Degrees
J4 Reservoir
Name = Receiving Tank
Liquid Surface Elevation = 10 feet
Liquid Surface Pressure = 30 psig
Pipe Depth = 10 feet
Click Run Model on the toolbar or from the Analysis menu. This will open the Solution Progress window. This window allows you to watch as the AFT Fathom solver converges on the answer. This model runs very quickly. Now view the results by clicking the Output button at the bottom of the Solution Progress window.
Open the Output Control window by selecting Output Control from the Output toolbar or Tools menu.
On the Display Parameters tab, click the Pumps button, and add the De-rating Head Correction factor (CH) to the Pump Summary output.
The Output Control window can also be used to configure the slurry output data. Click OK when you are finished.
The Slurry tab in the pipes section shows the slurry results. Here one can see that the velocity is 21.90 feet/sec, which is safely above the 11.48 feet/sec settling velocity. Other pressure drop and relevant slurry data can be viewed here.
Also shown is the Pump Summary in the General Section. There the required pump head is shown as 93.98 feet, and the de-rating correction factor is 0.7917. Hence a pump should be selected that can generate 93.98/0.7917 = 118.7 feet of head based on water.
Also of interest is the system curve. Select the Graph Results window tab then in the Graph Control tab in the Quick Access Panel select the Slurry System Curve tab.
By default the parameter to graph is Jm vs. Velocity. Select the units of Jm as ft/ft that will make it completely dimensionless as is typically done. Check the box for Water System Curve which cross-plots the water curve and then click Generate. The curves are shown in Figure 8.
A slurry of sand and water flowing through 570 feet of pipe was modeled. Total pipe head loss was determined and pump head requirements were calculated. A slurry system curve was created to allow the user to see where the system was operating with respect to solids settling.
