Scale Inhibition by Ultrasonic Reactor Operating in Pipelines

Calcium carbonate scaling can lead to several problems in the oil and gas industry, reducing pipe flow and deteriorating thermal processes. This work investigates the mechanism of scale inhibition using ultrasonic technology. An ultrasonic device designed to minimize the adhesion of calcium carbonate crystals in pipelines is detailed. The device equipped with three high-power ultrasonic transducers (60 W x 40 kHz) was used to stimulate calcium carbonate precipitation in a hydraulic system specifically assembled to study the calcium carbonate scaling by simultaneous injection of CaCl2·2H2O and NaHCO3. A transparent plastic hosepipe 5 m long was used as a proof-pipe enabling visual observation. Pressure drop and crystal morphology were evaluated. Ultrasonic field evaluation tests inside the developed device showed strong cavitation activity and significant erosion on aluminium foils. After 140 minutes of continuous flow through the pipe under US irradiation, volumetric flow rate remained stable. A reduction in hydraulic resistance of 42% was found, if compared to the test condition without any scaling protection. The morphology of the crystals evaluated by scanning electron microscopy showed that crystals became smaller and more rounded.