Development of models for multi-phase processes in the pore system of a filter cake on the basis of 3D-information

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Cake filtration belongs to the mechanical de-watering processes. These are a central step in numerous production lines of the chemical, pharmaceutical, biotechnological, food-, materials- and minerals industry. The main task is the efficient separation of particulate solids from the suspension liquid. The numerical investigations in this field have led to detailed scientific knowledge of the local cake structuring regarding idealized particles as well as of the flow in porous media. On the other hand, the engineering solutions still use strongly simplified 1D-approaches. This is due to the fact, that until some years ago it was quite impossible to generate detailed information on the properties of the pore volume. Therefore, integral parameters had to be used for the engineering calculations and the process design. The project is divided into two stages, which are combined to allow a better technological description of the mechanical de-watering processes of filter cakes. The pore system itself is characterized by high-resolution computer-tomography. These data sets will be used to develop a structure model of the pore system. The central point of this model is the definition of characteristic distributed parameters. The distributed parameters of the particle characterization, e.g. size and form, will be correlated with the distributed parameters of the pore structure. With this approach, it will become possible to determine the processing properties of the filter cake using the particle characterization. The connection of particle data with pore and process data uses a short cut approach. To achieve a real three-dimensional understanding of the pore structure, the tomography data will be visualized in a 3D virtual reality surrounding. This will enable us to set up a structural model, which bases on a real 3D understanding. The quantification of the technological aspects of porous flow applies the structure model. It aims at using the right distributed geometrical parameters for each physical effect. This allows a decoupling of capillary and friction effects, which in the established approaches use the same geometrical parameter (the hydraulic diameter). The process model will simplify the problem, for that it will be possible to use engineering calculation approaches. This avoids the application of time and resources consuming numerical methods. This further allows a rapid and still quantitative convincing design of filtration and gas differential pressure de-watering processes. Process control and automation as well as interlinked simulation tools need models, which only require a limited calculation capacity. They need rapid calculations to react on other processes. Using the short-cut structure and process model the result, the de-watering respectively, can be calculated from the input information, which are distributed particle properties.