Does the concentration ratio contribute to the scaling of circulating cooling seawater?

Due to the impact of freshwater shortage on coastal areas, coastal factories have gradually chosen seawater circulation cooling towers for industrial cooling. The circulating seawater easily generates thick scales, obstructs pipes, and affects heat transfer. Different from the development of scale inhibitors and membrane treatment, there are few fundamental researches on scale formation in seawater pretreatment. In this study, the effects of seawater concentration on scaling time and crystal shapes were investigated through on-line monitoring scaling experiments and scale collection. When the concentration of seawater increased (0.5–2.5 times), the scaling time was delayed, and the formation of large aggregates decreased. Subsequently, the scale delay of calcium carbonate caused by high ion concentration was confirmed by sodium and potassium ion gradient tests and the Visual MINTEQ model. The dynamic simulation further revealed that high ion saturation inhibits calcium and carbonate ions' collision, binding, and agglomeration. Sodium ions inhibit scale formation through electrostatic repulsion with calcium ions, while potassium ions occupy spatial sites around calcium ions. Furthermore, the aragonite formation tendency in highly ion-saturated solutions provides a theoretical basis for industrial carbon capture technology at the end of cyclic cooling. [Display omitted] •High concentration ratio of seawater inhibits scale formation.•Concentration of sodium or potassium solution affects the scaling time and the crystal form.•Collision, combination, and agglomeration process of scale-prone ions are hindered by other ions.•Seawater with a high circulation ratio is favorable for the formation of aragonite.