Modeling the vacuum filtration of fine coal. III. Comparison of models forpredicting desaturation kinetics

Three mathematical models devised by Wakeman, by Baluais, and by Nicolaou h ave been compared in their ability to predict the desaturation kinetics of fine (-0.5 +0 mm) coal using vacuum filtration. Although similar in their b asic 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 f rom the experimental data being deemed a success. All models predicted cake moisture after 300 seconds desaturation time to within 1 wt% moisture, exc ept 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 t imes (up to 50 seconds), the Wakeman model showed the best all-round perfor mance, never deviating more than 1.5 wt% from experiment, and frequently be ing much closer. The Nicolaou model was particularly good at predicting des aturation 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.