Modelling and Simulation of Multidimensional Fractionation in Fine Particle Systems and their Application

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For fine particle systems, a separation gap is observed for particle sizes in the range of 100nm to 10µm. In this transition region, facilities suffer from a lowered selectivity and separation efficiency. In order to be able to improve existing plants and processes, new fundamental knowledge on particle dynamics will be gained through numerical simulations in this project. It is based on a previous project in which a model for the prediction of sedimentation of arbitrarily shaped particles and distributed particle collectives was developed. The applicant focused on the shape of the particles in order to correlate parameters such as density, size, aspect ratio, sphericity and convexity to a multidimensional separation characteristic. In this project, the focus is on process engineering applications. For this purpose, the model is extended so that simulations of realistic particle collectives can be carried out in real application geometries. The main goal is the elucidation of multidimensional correlations of shape and operating parameters on the process scale to improve selectivity in the size range of the separation gap. On the one hand, particles have to be further characterized with respect to their dynamic properties in a flow by means of an angle-dependent resistance coefficient. On the other hand, statistical investigations have to be extended to real measured particle systems. An extension is also the consideration of process parameters, such as the spin number and field strengths of an externally applied E- or B-field. First, correlations of shape and process parameters are determined on a micro-scale with respect to particle dynamics. From this, maturity properties and finally resistance forces and diffusion coefficients for polydisperse particle collectives are derived. These are then incorporated into a population balance model for the process scale, which is described by coupling a Navier-Stokes equation and several advection-diffusion equations. The resulting simulation tool is used for investigations of application geometries such as chromatography columns, centrifuges and other equipment. At the end of the project, knowledge and an extended model as well as a simulation tool for the prediction of multidimensional fractionation will be available. By focusing on application geometries, the results contribute directly to improving the design of process plants.