Various kinds of corrosion will occur when the heat exchanger is used. After knowing the cause of corrosion, you can choose reasonable anti-corrosion measures to achieve the purpose of efficient use of equipment. How to do the anticorrosive work of plate heat exchanger?
(1) The corrosion inhibitor with chromate as the main component is commonly used in cooling water systems. Chromate ion is an anode process inhibitor. When it is combined with a suitable cathode inhibitor, it can obtain satisfactory and Economical anti-corrosion effect.
(2) Chromate-zinc-polyphosphate. The use of polyphosphate is because it has the effect of cleaning the metal surface and has the ability to inhibit corrosion. Polyphosphates can be partially converted into orthophosphates, and they can also generate large colloidal cations with calcium, inhibiting the cathodic process.
(3) Chromate-zinc-phosphate. This method is similar to the previous method except that sodium phosphate is used instead of polyphosphate. Carbamate phosphate can also be used in applications where the pH is higher than that specified for polyphosphate. Carbamate phosphate prevents scale and controls precipitation of calcium salts even at pH 9.
(4) Chromate-zinc-hydrolyzed polyacrylamide. Due to the dispersing effect of the polyacrylamide hydrolyzed by the cationic copolymer, it is possible to prevent or suppress the generation of scale to scale.
2. Electrochemical protection
Cathodic protection and anodic protection. Cathodic protection is the use of an external DC power supply to make the metal surface into a cathode for protection. This method consumes large power and costs a lot. Anode protection is to connect the protected heat exchanger to the anode of an external power source, so that a passivation film is formed on the metal surface, thereby being protected.