Revealing the complex spatiotemporal nature of crystal growth in a steel pipe: Initiation, expansion, and densification

Crystallisation fouling is a challenge in numerous applications. To mitigate fouling we need to determine the basic mechanisms involved in the process. While ex situ techniques have been widely used in previous studies, they cannot capture complex dynamic effects. We conducted an in situ investigation of the dynamic effects of crystallisation fouling in a steel pipe (length 3 cm, diameter 3 mm) using X-ray micro-computed tomography (μCT) over more than six days. We employed a custom-developed image reconstruction algorithm, which ensured high spatiotemporal resolution from a laboratory instrument. We quantified the evolving fouling using advanced segmentation techniques of 4D images. To understand how the pipe interface structure impacts reactive transport, the experimental geometries of the flow system were used to perform computational fluid dynamic simulations. These new data allowed us to identify three growth phases: initiation, expansion, and densification. •Three phases of surface crystallisation were identified.•The rate of crystal deposition varied by a factor of 4 over a period of six days.•Reactive transport modelling was coupled with the experimental geometries.•Novel dynamic reconstruction algorithms were developed to treat 4D X-ray CT.•In situ X-ray μCT was used to examine crystallisation fouling for more than six days.