Experimental study on the scale inhibition effect of the alternating electromagnetic field on CaCO3 fouling on the heat exchanger surface in different circulating cooling water conditions

Abstract

Scaling on the heat exchanger surface resulted in large equipment cleaning, maintenance expenses and safety issues in the industrial production. To remove the heat exchanger scaling, research on the scale inhibition effect of the alternating electromagnetic field on CaCO3 fouling on the heat exchanger surface with the selected four Mg2+/Ca2+ molar ratios in circulating cooling water. Four indicators, namely, heat transfer resistance, scale inhibition rate, the growth rate of CaCO3, and conductivity were discussed extensively. The experimental results demonstrated that remarkable scale inhibition effect occurs, when the Mg2+/Ca2+ molar ratios is 0 and 1:1.2 with 46.80% and 39.28% of the scale inhibition rate, respectively. Compared with the control group, the heat transfer resistance was decreased, the adherent scale growth rate was slowed down, and the rising stage time was shortened in the experiment group. In addition, the decreased of conductivity in the experiment group indicated that the alternating electromagnetic field promoted the crystallization in the solution. XRD and SEM analysis demonstrated that the alternating electromagnetic field and Mg2+ could promote aragonite crystallization, reduce the polymerization degree, and decrease the crystal particle size of CaCO3. Affecting the crystallization process of adherent scale and promoting the homogeneous precipitation of non-adherent scale in solution is the key to the alternating electromagnetic field scale inhibition technology. This study could provide a guidance for the parameter selection in electromagnetic field scale inhibition technology of industry application.