Cake growth measurement

Figure 4.18 Schematic of a state-of-the-art apparatus for investigating the filtration, displacement washing and gas deliquoring phases of the filter cycle. (1) suspension feed vessel (2) wash liquor feed vessel (3) filter cell (4) rotary index table (5) electronic balance (6) pressure regulator. The inset photograph shows fully automated apparatus for obtaining filtration and deliquoring data including facility for transient measurements of cake growth and state.

This experimental technique also allows the deposit growth to be characterized versus time by applying the method presented above for successive images and thus the cake growth kinetics to be obtained. The image acquisition rate is chosen by the operator (down to a few images per second) so that this measurement technique could be used for various membrane fouling kinetics. 

The comparison between measured and calculated values shows good agreement. The measured order of magnitude and cake growth dynamics seem to be correct. Nonetheless, the evolution of the measured thickness with the deposited mass is nonlinear. This is due to the modification of the deposit structure with time which is not taken into account in the model. The limitation of the model is... 

Thus, at each time increment, the newly formed surface layer has not been compressed and the mass in the surface layer is estimated by the measured increase in fouling layer thickness due to cake growth and the surface porosity of a... 

NMR imaging allows the monitoring of the composition of a sample by measuring the distribution of mobile protons in any slice of the specimen (Buetehom et al, 2011). The microfiltration process (permeate flow and cake growth) of model solutions (water or silica suspensions) has been visualised using NMR imaging (Buetehom et al, 2011). 

The initial permeate flux is 204 Lh m . It decreased rapidly during the first time period (fiom 0 s to 1500 s) and then more slowly to 20 L h m . At the same time, it was possible to measure the cake thickness growth. The final thickness was 55 pm for a total deposited mass of 80gm and a relative flux decrease of 87%. Analysis of the variations of the flux decrease and of thickness growth with time enabled several layers with different structures to be distinguished. The... 

Li, J. X., Hallbauer-Zadorozhnaya, V. Y., Hallbauer, D. K., and Sanderson, R.D. (2002a). Cake-layer deposition, growth and compressibility during microfiltration measured and modeled using a non-invasive ultrasonic technique. Ind. Eng. Chem. Res. 41, 4106. 

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