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Protection of heat exchanger
Mar 19, 2020

In view of the corrosion situation discussed above, the following anticorrosion methods are proposed: corrosion inhibitor and electrochemical protection are mainly introduced here.


(1) corrosion inhibitor with chromate as the main component of the corrosion inhibitor is commonly used in cooling water system, chromate ion is an anode (process) inhibitor, when it is combined with the appropriate cathode inhibitor, can get a satisfactory and economic corrosion protection effect. Chromate - zinc - polyphosphate: polyphosphate is used because it is a clean metal surface function, corrosion inhibition ability, polyphosphates can be partially converted to orthophosphates, they can also be formed with calcium large colloidal cation, inhibit the cathode process. Chromate - zinc - phosphonate: this method USES phosphonate sodium in place of polyphosphates. Similar to the previous method, aminomethyl phosphates can also be used where the pH specified for polyphosphates is higher. Aminomethylphosphonate prevents scaling and controls the precipitation of calcium salts even at a pH of 9. Chromate - zinc - hydrolyzed polyacrylamide: prevents or inhibits scale formation due to the dispersion of polyacrylamide hydrolyzed by cationic copolymers.


The electrochemical protection adopts cathode protection and anode protection. Cathodic protection is the use of external dc power, so that the metal surface into the cathode to achieve protection, this method of large power consumption, high cost. Anode protection is the protection of the heat exchanger with an external power anode, so that the metal surface to generate a passivation film, so as to be protected.

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