Electrochemical Anti-corrosion Maintenance Of Plate Heat Exchangers

Knowing the causes of various corrosion in heat exchangers and selecting appropriate anti-corrosion measures can achieve the goal of efficient utilization of equipment. Regarding the corrosion situation, the following anti-corrosion methods are proposed: here we mainly introduce corrosion inhibitors and electrochemical protection.
1. Corrosion inhibitor
Corrosion inhibitors mainly composed of chromate are commonly used in cooling water systems. Chromate ions are an anodic (process) inhibitor, and when combined with suitable cathodic inhibitors, satisfactory and economical anti-corrosion effects can be achieved.
Chromate zinc polyphosphate: The use of polyphosphate is due to its ability to clean metal surfaces and inhibit corrosion. Polyphosphate can be partially converted into orthophosphate, which can also form large colloidal cations with calcium to inhibit cathodic processes.
Chromate zinc phosphonate: This method uses sodium phosphonate instead of polyphosphate and is similar to the previous method. Aminomethylphosphonates can also be used in situations where the pH value specified for polyphosphate is higher. Aminomethylphosphonates can prevent scale formation and control the precipitation of calcium salts even at a pH of 9.
Chromate zinc hydrolyzed polyacrylamide: Due to the dispersing effect of cationic copolymer hydrolyzed polyacrylamide, it can prevent or inhibit the formation of scale and dirt.
2. Electrochemical protection
Adopt cathodic protection and anodic protection. Cathodic protection is the use of an external DC power source to turn the metal surface into a cathode for protection. This method consumes a large amount of electricity and is expensive. Anodic protection is the process of connecting a protected heat exchanger to an external power source's anode, creating a passivation film on the metal surface to provide protection.