Corrosion issues in the alkali heat exchanger of electrolytic cells
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This post was last edited by sunjl1981 on 2013-1-7 00:17. We used Ni-based plate heat exchangers for the alkali heat exchange in our electrolytic cells; however, corrosion and leakage occurred after just a short period of use (a few months). After disassembly and inspection, pitting was found on both the alkali side of the plate and the side in contact with the heat exchange medium (cooling water or steam). There is no significant scaling on the heat exchange medium side. However, corrosion occurs on the plate side facing the alkali, there is no corrosion on the side facing the heat exchange medium, and there is no corrosion on the alkali side facing the heat exchange medium. Someone in the company said it could be electrical corrosion; I hope everyone can provide an explanation. Also, if it is indeed caused by electrical corrosion, how can we avoid it or take precautions against it? ， ， -
There might be a problem with the heat exchanger itself: firstly, the material used is defective; secondly, the manufacturer reversed the materials on either side of the composite plate during production.
It should be a quality issue. I’ve had mine for four and a half years; after cleaning off the dirt, it’s as shiny as new. Imported equipment.
Our heat exchangers are made of pure nickel, not composite panels.
Has anyone encountered a similar situation during operation?
When NI material is used, corrosion on the alkaline side is generally the most likely to occur due to electrochemical effects. Check the grounding of the electrolyzer, as well as whether the pipes connecting the alkaline pipeline to the electrolyzer are insulated.
It is mainly the nickel material that corrodes in the presence of high chloride levels. The data regarding corrosion can be looked up; as far as I remember, the chloride concentration should be below 25PPm. Moreover, the corroded areas tend to turn green or black. Consider switching to 904; otherwise, control the chloride ions.
1. There is a problem with the material of the plate; its carbon content is too high. Testing method: pure nickel has strong magnetism while alloys have weaker magnetism； 2. The chloride content in the coolant is above the limit, causing corrosion in the gaps ； 3. If the chloride ions in the alkaline solution exceed the specified limit, corrosion will occur in the relevant equipment and pipelines.