Calcium carbonate scaling control on heat plate exchange surfaces using ultrasound

Calcium carbonate scaling can lead to serious operational problems in industrial facilities, its control is of fundamental importance, especially in heat transfer equipment. This work evaluated the use of ultrasound to prevent calcium carbonate scaling, focusing applications involving heat transfer equipment. Tests were conducted using a metal surface coupon, collected from a plate heat exchanger, as sample holder. Ten depositions runs were performed by a semi-continuous process using CaCl 2 ·2H 2 O and NaHCO 3 solutions as reagents. A well-marked cavitation was verified after erosion tests on aluminum foil. Two experimental situations were tested: (i) No ultrasound applied to the crystal formation medium and (ii) ultrasound irradiation using Langevin transducer at 40 kHz and 31.5 Watt, where scaling mass and crystal morphology were evaluated. Calcium carbonate mass deposition was reduced under ultrasound action (up to 80.7%), this radiation had a strong influence on size and morphology of formed crystals, making them 70.8% smaller and rounded shape, thus less adherent to titanium metal coupons.