(SSL Module Only) On the Solids Definition panel, users define the Slurry Calculation Method and Solids Specifications. These inputs are the same as for both the Basic Water Slurry Input and the Advanced Slurry Input.

Override options are provided for a number of parameters that allows users to modify data pulled from libraries should modeling requirements need this.

Figure 1: Solids Definition panel when Detailed Slurry Calculation Method and Calculated M are selected

Slurry Calculation Method

There are three calculation methods available to model slurry. Each method requires different amounts of input data resulting in the use of different calculations. These calculations are described in the Slurry Calculation Methods section.

• Minimal Method - Used in the preliminary design phase where only rough data are available. The solids density, sliding friction coefficient, and solids concentration are the only parameters needed. However, due to the minimal data the calculations should only be used for early stage approximations because it often over-predicts losses. This is a conservative method that assumes a fully-stratified sliding bed.

• Simplified Method - Additional information is required and gives a better solution. This method requires the solids density, d50 particle size, a user-specified M exponent, and the solids concentration. This method assumes heterogeneous flow with suspended particles. This is a more accurate model than the Minimal method because it accounts for more slurry definition.

• Detailed Method - The default and provides the most rigorous solution methodology. The solids density, d50 particle size, terminal velocity parameter, and the solids concentration are required. Additionally, if the M exponent is to be calculated, the d85 particle size is also required. As with the Simplified Method, this method also assumes heterogeneous flow with suspended particles.

Solids Specifications

In the Solids Specification area, select from the following options for solids:

• No Solids Added - The model will run using the carrier fluid without any solids, no further input is required.

• User Specified Solids Added - Define the solids using the Solid Properties fields.

• From Library - Use solids already defined in the Solids Library. Note no default solids library is provided by AFT, library items must be defined first in the Library Manager to be available here.

Solids Properties

By selecting User Specified Solids Added, the Solids Properties fields become available to define the solids. Depending on the Slurry Calculation Method selected at the top of the Solids Definition panel, certain fields are required:

• Minimal

  • Density

• Simplified

  • User Specified M (Stratification Ratio Exponent)

  • Density

  • d₅₀

• Detailed

  • M (Stratification Ratio Exponent)

  • Terminal Velocity Parameter

  • Density

  • d₅₀

  • d₈₅ - if Calculated M (Stratification Ratio Exponent) is selected

The M (Stratification Ratio Exponent) is a parameter in the stratification ratio equation. The user can allow AFT Fathom to calculate M based on best available methods, or input M directly. The process of estimating M from recorded data is discussed elsewhere.

The Terminal Velocity Parameter must be entered when using the Detailed calculation method. This can be entered as either a Shape Factor (K) or the ratio of the particle’s terminal velocity (V_t) to that of a sphere (V_ts), designated as V_t / V_ts (X_i). If a Shape Factor is entered, it is used in conjunction with the graph shown in Wilson, et al, 2006Wilson, K.C., G.R. Addie, A. Sellgren and R. Clift, Slurry Transport Using Centrifugal Pumps, 3rd Ed., published by Springer, 2006., on page 47, to obtain a value for Xi. Typical shape factors are given in Wilson, et al, 2006, on page 46 where K = 0.26 for sand.

In the lowest area, enter the required values for mean density of the solid particles, d₅₀ (mass-median particle diameter) and d₈₅ (diameter for which 85% by mass of the particles are finer).