Velocity in pipe X is less than the deposition velocity

A Warning message in AFT Fathom

(SSL Module Only)

Full Message Text

Steady-State:

Velocity in pipe W is less than the deposition velocity. Results may be inaccurate. (Velocity: Y, Vsm: Z)

Transient with the XTS Module:

Velocity in pipe W is less than the deposition velocity at time X. Results may be inaccurate past this time step. (Velocity: Y, Vsm: Z)

Explanation

Engineers often want to avoid operating settling slurry systems in such a way that the bulk slurry velocity (V_m) is less than the deposition/settling velocity (V_sm). This warning indicates that the velocity is in fact less than the deposition velocity which can cause operational problems including stationary beds or plugging of pipes. The methods available in the SSL Module cannot model stationary beds, and thus the results may not be accurate under these conditions. The farther the velocity drops below V_sm the more uncertainty in the results.

Required Action

Adjust the model such that the velocity is higher than the deposition velocity. If this is not possible, then it may indicate operational problems in the real system, or you must accept that the results will be incorrect.

Potential adjustments:

• Decrease the pipe size

• Increase the flowrate

• Reduce the slope of the pipe