P 09/02


Deep bed filtration in real porous structures - Combination of µCT and NMR

The filtering efficiency in deep bed filtration is often described by empirical filtration coefficients only while the internal processes of deposition of particles in the filter structure remain unknown. An increased knowledge of the microscopic deposition processes would on the other hand increase the possibilities for an optimization of the filtration process significantly. Moreover the flow structure inside the porous medium will affect the deposition process considerably and thus it should be known too if a detailed description of the filtration process is pursued. The main problem in obtaining the relevant data results from the complex inner structure of the filter bed on the one hand and in addition from the fact that the deposition sites can not be detected - e.g. by optical means - from outside during the filtration process. A way to resolve these restraints is provided by X-ray micro tomography. This enables the acquisition of three dimensional structure data of the filter bed (here glass spheres shown in blue in the figure) as well as of the deposition sites (here shown in red). By means of digital image processing a quantitative analysis of this data and thus a detailed understanding of the filtration process itself becomes possible. It will be a goal of the project to apply X-ray tomography to deep filtration in real, complex filter bed structures and to understand the dependence of the deposition characteristics on typical filtration parameters like e.g. filtration speed or size ration of deposit particles and filter pores. Moreover the project is entitled to provide three dimensional structure data for simulations inside the MINEMIMA collaboration and the link towards NMR-tomography will open the possibility to connect the deposition characteristics with the flow structure inside the porous structure.


Contact: Odenbach, Mikolajczyk