Investigation of Fouling on Random Packing Using Microfocus X-ray Computed Tomography

Fouling, the unwanted deposition of solids on heat or mass transfer surfaces, challenges chemical processes by reducing performance and increasing costs. To our knowledge, we are the first who are using microfocus X-ray computed tomography (micro-CT) to investigate and quantify fouling on random packings in this study. For this purpose, a screening test rig was integrated in a micro-CT scanner, enabling high-resolution imaging of crystallization fouling on various random packing types. Using this technique, initial deposits can be visualized and the nonlinear growth of deposits can be monitored during the experiment. Quantitative analysis was performed by processing the reconstructed attenuation data sets to determine the volumetric fraction of deposits. Deposit growth was correlated with the evaporated water mass, accounting for mass transfer. Comparisons among three industrial random packings (Hiflow 15-7 PP made of polypropylene, Hiflow 20-4 made of ceramic, and Pall-Ring 15 made of metal) revealed that while fouling on the Hiflow 15-7 PP and Pall-Ring 15 primarily occurs at the edges of the packing elements, on the Hiflow 20-4 ceramic packing it is mainly present on the surface planes. In addition, the rate of deposit growth is higher on the ceramic packing. Furthermore, micro-CT was able to detect deposits at an earlier stage than with conventional pressure drop measurements. These insights improve the understanding of fouling behavior and provide data for optimizing packing design and validating computational fluid dynamics models.