Fluidized beds are used in a variety of industries ranging from pharmaceuticals to agriculture and energy. Compared to other common reactor types in process engineering, fluidized beds exhibit advantageous mass and heat transfer properties. Despite their widespread use, our fundamental physical understanding of the hydrodynamics occurring within fluidized beds is still relatively poor. The main reason for this shortcoming is the fact that fluidized beds are challenging to study experimentally because they are optically opaque. Traditionally, the majority of fluidization measurements were based on either intrusive probes, that measure the local solids concentration or velocity of particles or the gas pressure in one specific location of the bed or optical measurements of pseudo-two-dimensional (pseudo-2D) systems. These experiments, however, cannot provide spatial resolution (probe measurements) or are heavily affected by the apparatus walls (pseudo-2D systems). In recent years, non-intrusive tomographic techniques are increasingly used to study fluidized beds. Magnetic resonance imaging (MRI), a technique that has been mainly applied in the medical field, is particularly suited for obtaining spatially and temporally resolved dynamic information from the interior of fluidized beds.
In this collaborative project between SPE and IPI (Institute of Particle Imaging) fluidized beds with and without vibration will be constructed and studied using conventional state-of-the-art inline process analytics, numerical modelling, as well as real-time MRI. The 3D MRI data obtained by the work group IPI will be compared with commonly used correlations, and with the results of conventional measurement techniques. In addition, numerical investigations in the form of computational fluid dynamics simulations coupled with the discrete element model (CFD-DEM) will be performed by the work group SPE. These numerical models will be tested and their prediction accuracy of the fluidization hydrodynamics will be evaluated using the MRI data. Besides classical fluidized beds, vibrated fluidized beds will be investigated to analyze the effect of vibration on the actual hydrodynamics.