New dynamic test rig to study the influence of ultrasound on calcium carbonate scale formation

• Ultrasound reduces CaCO 3 scaling by altering nucleation and crystal growth. • Induction time analysis reveals significant acceleration under sonication. • CaCO 3 polymorphs shift from calcite to vaterite under ultrasonic treatment. • Ultrasound was able to reduce pressure drop and adhered mass on the rig. • Study provides a mechanistic understanding of ultrasound in scale control. Inorganic scale in oil and gas pipelines is a critical problem in the petrochemical industry, causing reduced flow in pipes and heat exchangers. Carbonates deposition is persistent and influenced by several factors such as temperature, pressure, and pH. This paper presents a Precipitation and Scaling Test Rig (PSTR) as an experimental platform to study the influence of ultrasound on calcium carbonate scale formation. This tool enables the investigation of the three main factors influencing inorganic scale formation (temperature, pressure, and pH) and allows experiments varying reagents flow rate, reagents concentration, and applying physical and chemical scale inhibitors during inorganic crystal formation reactions. To study the effects of ultrasound on calcium carbonate scale formation, two tests were performed: one without ultrasound irradiation and the other with ultrasound applied during the calcium carbonate crystallization process. In both cases, the same process parameters were used on the PSTR. The induction period was analyzed by measuring conductivity. The pressure drop across a deposition module was monitored. The results indicate that ultrasonic irradiation during crystallization accelerates crystal nucleation, prevents scale formation, and modifies the crystallographic phase of calcium carbonate crystals. Additionally, SEM images, composition, and phases of produced crystals showed changes in crystal morphology when ultrasound was applied.