SPP 1679: Dynamic simulation of networked solid processes
The central objective of the priority program was to create numerical tools for a dynamic simulation of networked solid processes. For this purpose, physically based, dynamic models of different apparatuses and processes of solids process engineering have to be formulated and implemented. With regard to the simulation of networked solid processes, some requirements arise for these models. The models should have as wide a range of application as possible; in particular, they should not be limited to specific material systems. For this purpose, the disperse properties of the solids must be taken into account (particle size distribution, composition distribution, density, particle shape and other properties). In order for the models to be used for the simulation of complex networked solids processes, they must not have too high requirements in terms of computer resources, despite the aforementioned boundary conditions. For the formulation of the models, experimental investigations and numerical experiments with CFD and DEM methods, respectively, were carried out.
Process modeling for dynamic disperse separation and deposition processes
Modules for the flow sheet simulation (FSS) of separation and redispersion processes in an electrostatic precipitator are implemented in the framework system of the flow sheet simulation developed in SPP 1679. The separation and redispersion functions are thereby derived from numerical and experimental flow and particle analyses, with scaling of the model based on process parameters, geometry variations and material properties. The use of different model materials (Ulmer Weiss and Pural NF) showed material-dependent dynamic deposition behavior in the experiments. Samples of representative wall layers in the microscope showed a temporally invariant homogeneous surface structure for Ulmer Weiß, while the roughness of the layer grew steadily in the tests with Pural. In the simulations, the degree of deposition of particles is determined by the effective electric field passed through. This changes its amplitude and shape with the use of different electrode geometries. The macroscopic model reproduces this behavior via a geometry parameter and achieves good agreement with the separation curves of the CFD simulation. Plant dynamics and scaling to industrial plant sizes, stock systems and climatic conditions were the focus. The flow sheet process model is extended to these use cases, with particular emphasis on the redispersion of already separated particles as internal process dynamics. The process modules to be derived are implemented and applied on the basis of the framework system developed in the SPP. The application of the model was able to show that dynamic deposition processes can be represented in the FSS as a function of plant, process conditions and material.