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Separation Science and Technology, Vol.35, No.10, 1467-1484, 2000
Modeling the vacuum filtration of fine coal. III. Comparison of models for predicting desaturation kinetics
Three mathematical models devised by Wakeman, by Baluais, and by Nicolaou have been compared in their ability to predict the desaturation kinetics of fine (-0.5 +0 mm) coal using vacuum filtration. Although similar in their basic approach and many of their underlying assumptions, the models diverge considerably in the techniques used to solve the equations of air and water flow through a porous filter cake. The models were assessed as a function of vacuum level and cake height, with a deviation of below 1 wt% moisture from the experimental data being deemed a success. All models predicted cake moisture after 300 seconds desaturation time to within 1 wt% moisture, except Baluais, which deviated significantly (by 2.3-3.2 wt% moisture) at the lowest vacuum (40 kPa) and lowest cake height (8-9 mm) tested. At shorter times (up to 50 seconds), the Wakeman model showed the best all-round performance, never deviating more than 1.5 wt% from experiment, and frequently being much closer. The Nicolaou model was particularly good at predicting desaturation kinetics for the thinnest cakes. Taking the data set as a whole, there were no obvious trends for any of the models in systematically under- or overestimating product moisture.