Pilot plant experiments and modeling of CaCO3 growth inhibition by the use of antiscalant polymers in recirculating cooling circuits

Abstract Recirculating cooling circuits are prone to the deposition of scale on heat exchangers and packing surfaces. The addition of antiscalant polymers is efficient for inhibiting the precipitation of calcium carbonate (CaCO 3 ) because polymers block the active growth sites. In this study, growth inhibition of calcite by using such polymers in industrial pilot plants operating with natural river water, which is critical to mimic a full-scale cooling circuit and accurately evaluate scale inhibition, was reported. Efficiencies of three commercial polymers were compared. The polymers thus investigated demonstrated comparable efficiencies and similar responses to changes in operating conditions. An adsorption-based model was proposed to quantify the inhibition of precipitation kinetics with respect to the process operating conditions and water qualities. Then, the model was validated at a wide range of polymer concentrations, temperatures, and water qualities, representative of industrial systems. A small amount of polymer was sufficient to affect bulk-scale prevention, albeit the efficiency became constant at high polymer concentrations. Under these conditions, a complementary treatment such as acid injection is necessary.