Principle of corrosion prevention by injecting corrosion inhibitors into the overhead line of the distillation tower in hydrogen-handling units
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Dear hydrogenation expert, what is the principle behind adding corrosion inhibitors to the top stream of the distillation tower in hydrogen-related facilities for corrosion protection? I hope you can provide an answer.
There are three types of mechanisms by which corrosion inhibitors work: ① Phase-forming film mechanism: The corrosion inhibitor forms a protective film on the metal surface through oxidation or deposition, preventing contact between the medium and the metal. ② Adsorption membrane mechanism: The corrosion inhibitor binds to the active metal centers through physical or chemical adsorption, preventing the medium from coming into contact with these active metal centers, thereby protecting the metal. Physical adsorption refers to the binding of corrosion inhibitors to metal active centers through the attractive forces between molecules or ions ； Chemical adsorption refers to the formation of complexes between corrosion inhibitor molecules and metal atoms, with their hydrophilic groups bonding to the metal and their hydrophobic groups staying away from it. Such corrosion inhibitors are mostly organic corrosion inhibitors. ③ Electrochemical mechanism: These corrosion inhibitors slow down the corrosion of metals by increasing the resistance at the anode or cathode where corrosion occurs.
Corrosion inhibitors are generally added based on the film-forming principle
Correction: The distillation tower should be considered part of the non-hydrogen-related section. The principles of corrosion prevention using corrosion inhibitors can be divided into two categories: film-forming corrosion inhibitors and neutralizing corrosion inhibitors. Film-forming corrosion inhibitors create a protective layer on the inner side of the pipe walls, preventing corrosive substances from coming into direct contact with the pipe walls thereby providing corrosion protection. A large amount of these inhibitors needs to be injected at the beginning; once a film has been formed, the amount of inhibitor required can be reduced, with only enough to maintain that film being necessary. Neutralizing corrosion inhibitors: They neutralize the corrosive agents in the medium through chemical reactions, thereby eliminating their corrosive effect. Adjust the amount of corrosion inhibitor added according to the corrosion medium level.