2012 AIChE Annual Meeting

(640a) Improvements On Three Methods of Thickener Area Calculation

Author

Salama, A. I. A. - Presenter, Natural Resources Canada


IMPROVEMENTS ON THREE
METHODS OF THICKENER AREA CALCULATION

A. I. A. Salama

 

CanmetENERGY-Devon

Natural Resources Canada

Suite A202, #1 Oil Patch Drive, Devon, Alberta, Canada T9G 1A8

Phone (780) 987-8635, Fax (780) 987-8676

E-mail: Ahmed.Salama@nrcan-rncan.gc.ca   Abstract

  Thickener cross-sectional Area (A) may be estimated using either
one of the methods; Merta and Ziolo (MZ), Talmage and Fitch (TF), and solids sedimentation
flux (SSF).  The MZ method is based on determining A's at different zone
solid-concentrations.  The TF method was developed using intermediate slurry solid
mass concentration (C) and thickener underflow (U), C, as a reference. 
In the SSF method, two correction-factors to the solids terminal velocities are
used.  

Keywords: Thickener cross-sectional, Thickener,
Clarifier, Solid-liquid separation, Sedimentation solids flux

Conclusions

 

The methods of MZ, TF, and SSF revisited and improvements on these
methods have been proposed.  These methods are selected due to their simplicity
and practicality.  The MZ method utilizes single solids settling (SS) curve. 
The original TF method was developed for any intermediate slurry C and
using the thickener U C as reference.  Again, the TF method uses a
single settling curve.  In the TF method the reason for the overestimation of A
is identified.  In the SSF method, two models of correction factors for Us(C)
are proposed.  The SSF method can be applied using single SS test and an
analytical model is needed to determine the settling velocity at different
slurry solid mass concentrations.  In SSF and using a single settling curve a
model for the settling curve is needed. However, In case of multi settling
tests, the method is applied directly because the initial settling velocities
at different slurry solid mass concentrations are known. Based on the results reported in this paper, general conclusions
can be drawn: µ        
The MZ method has been extended to show how the local maximum A
can be determined. µ        
In the TF method the source of A overestimation is identified. µ        
The SSF method, expressions for the optimal SF's and the
corresponding A's are developed. Single
settling test data are used to demonstrate the MZ method and multi-settling
tests data are used to demonstrate the SSF method.  In the SSF method, the RZ (Richardson
and Zaki, 1954) correction factor, and Christian (1994) and Wilson and Lee
(1982), correction factor for   w(C) are demonstrated.
See more of this Session: Industrial and Environmental Fluid Solid Separations

See more of this Group/Topical: Separations Division