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

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.

Automated summary

Scaling on the heat exchanger surface can lead to expensive cleaning, maintenance, and safety issues in industrial production. In this study, the inhibition effect of an alternating electromagnetic field on CaCO3 fouling was investigated using different Mg2+/Ca2+ molar ratios in circulating cooling water. Several indicators, including heat transfer resistance, scale inhibition rate, CaCO3 growth rate, and conductivity, were extensively discussed. The results showed that significant scale inhibition occurred when the Mg2+/Ca2+ molar ratios were 0 and 1:1.2, with scale inhibition rates of 46.80% and 39.28% respectively. Compared to the control group, the experiment group experienced decreased heat transfer resistance, slowed adherent scale growth rate, and shortened rising stage time. The decreased conductivity in the experiment group indicated that the alternating electromagnetic field promoted crystallization in the solution. XRD and SEM analysis demonstrated that the alternating electromagnetic field and Mg2+ could promote aragonite crystallization, reduce polymerization degree, and decrease crystal particle size of CaCO3. The key to the alternating electromagnetic field scale inhibition technology is affecting the crystallization process of adherent scale and promoting the homogeneous precipitation of non-adherent scale in solution. This study can provide guidance for parameter selection in the electromagnetic field scale inhibition technology in industrial applications.