Pilot Scale Application of a Rapid Instantaneous Corrosion Rate Monitoring System

摘要

The corrosion rate of metal alloys in power plant cooling system is an important operational parameter, used to evaluate the performance of the corrosion inhibitors. Application of an instantaneous corrosion rate monitoring system will facilitate corrosion management of the overall system by improved regulation of corrosion inhibitor dosing. In this study, a rapid instantaneous corrosion rate monitoring system was used to evaluate instantaneous corrosion rates of mild steel, copper and cupronickel alloys immersed in cooling water of a pilot scale cooling tower. The instantaneous corrosion rate monitoring system was developed by combining the gravimetric weight loss method and electrochemical polarization resistance method. Pilot scale application involved measurement of electrochemical polarization resistance using a three-electrode system. Instantaneous corrosion rates were obtained using the electrochemical polarization resistance values and the modified Stern-Geary coefficients of respective metal alloys. The modified Stern-Geary coefficients were previously determined in bench scale laboratory experiments for each of the metal alloys of interest. The system, tested in the pilot scale cooling towers, gave instantaneous corrosion rates for different metal alloys. It successfully indicated the difference in corrosiveness of different cooling waters, which was also revealed from the average corrosion rate data obtained by gravimetric weight loss method.