In view of the related corrosion of plate heat exchangers, the following anti-corrosion methods are proposed: Here we mainly introduce corrosion inhibitors and electrochemical protection.
1. Corrosion inhibitor
The corrosion inhibitor with chromate as the main component is commonly used in cooling water systems. Chromate ion is an anode inhibitor. When it is combined with a cathode inhibitor, it can have a satisfactory and economical anti-corrosion effect.
Chromate-zinc-polyphosphate: Polyphosphate is used because it has the function of cleaning the metal surface and has corrosion inhibition ability. Polyphosphate can be partially converted into orthophosphate, and they can also form large amounts with calcium. The colloidal cation.
Chromate-zinc-phosphonate: This method uses sodium phosphonate instead of polyphosphate. Similar to the previous method, carbamate phosphate can also be used for a higher pH than the specified value for polyphosphate. High occasions. The amino methylene phosphonate can have no scale, even if the pH
A value of 9 can also control the precipitation of calcium salts. Chromate-zinc-hydrolyzed polyacrylamide: due to the dispersing effect of the cationic copolymer hydrolyzed polyacrylamide, it can prevent the generation of scale into dirt.
2. Electrochemical protection
Use cathodic protection and anode protection. Cathodic protection uses an external DC power supply to turn the metal surface into a cathode to achieve protection. This method consumes a lot of power and is expensive. Anode protection is to connect the protected plate heat exchanger to the anode of an external power supply to generate a passivation film on the metal surface to obtain protection.