Erosive ions in industrial boiler water on the corrosion behavior of water-wall tubes

The maximum allowable content of chloride ion in industrial boiler water is closely related to the concentration ratio and operating conditions, the reasons for industrial boiler can not be operated under too high concentration ratio is due to the limit of Cl- content. There are many studies for the electrochemical corrosion behavior of carbon steel caused only by chloride ion, but few studies for calcium and bicarbonate ions on the electrochemical corrosion behavior of carbon steel. In order to study the corrosion of water-wall tubes for industrial boilers (20# carbon steel) caused by chloride ion, the erosive anion (Cl-) and Ca2+, electrochemical impedance spectroscopy and Tafel polarization techniques were performed. Autoclave static experiments were performed to study the corrosion inhibition property of carbon steel with 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP) additive in industrial boiler water medium. The results showed that Cl- could promote the corrosion of carbon steel obviously, HEDP has a good corrosion inhibition effect on 20# carbon steel at a concentration of 25 mg/L; Lower concentration Ca2+ in industrial boiler water could promote the corrosion while addition of higher concentration Ca2+ could inhibit the corrosion. It can provide a reference for the safe operation of the industrial boiler. © (2013) Trans Tech Publications, Switzerland.