Corrosion of Ni plates in ion membrane electrolysis alkali coolers
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This post was last edited by sunjl1981 on 2013-1-6 at 22:57. Our company uses Woody channels; during production, it was found that the 31E001 alkali cooler (used in the electrolysis process, not for cooling the finished alkali) is made of Ni material. Within less than 2 years, pitting corrosion occurred at the part in contact with the cooling water, which contained trace amounts of alkali； Using SS904 and SMO254 instead results in a longer service life compared to using Ni; in my opinion, the problem lies with the cooling water, which contains substances that cause corrosion of Ni. Our company uses water from cooling towers; oxygen-induced corrosion is the most likely cause. I would appreciate guidance and exchanges from colleagues in this field. # + + .
We have had similar accidents as well; it seems that corrosion is most evident in the nickel heat exchangers, and the reason for this is not entirely clear. It seems to be related to under-scale corrosion in circulating water. Apply a fungicide.
It should be caused by residual chlorine and chloride ions in the circulating water
Could you explain the principle? Or please pass on some relevant information, thank you. renzongkai@tom.com
A situation similar to the poster’s has also occurred in our factory. The main reason for this in our case is that the disinfectant used in the circulating water system is sodium hypochlorite; if an excessive amount is added, the excess free chlorine causes corrosion
Free chlorine has a quite severe effect on nickel corrosion; the cathode plate I’ve seen with the most damage had 13 holes
Reply to 6# Zhang Yongguo: Thank you all for your replies. The circulating water used in our company’s ion exchange membrane system, model 31E001, usually contains disinfectants produced by specialized manufacturers; it does not contain chlorine or hypochlorous acid. This water is of the same quality as tap water produced by thermal power plants (the only difference being that chlorine is not added). However, the water used in our company’s thermal power plant contains polyaluminum chloride, and it is likely that oxidation has occurred due to repeated contact between this substance, the circulating water from the cooling tower, and air. The corrosion spots on the nickel plates appear green, and there are multiple corrosion sites on the cooling water side. After consulting with foreign experts, it was suggested that Hastelloy C2000 could be used for the plate exchangers. I wonder if any other manufacturers in this industry use this material. For our chlorine drying unit, tower No. 1 uses Hastelloy C273 for the sulfuric acid plate exchangers, and these have been in use for over ten years now. The cooling water used is from the same cooling tower, and the materials currently in use have proven to be effective. The main issue regarding corrosion is likely the problem with the cooling water.
Using Hastelloy C2000 for catholyte heat exchangers is absolutely no problem, but the cost is very high
Chloride ions – have you analyzed the chloride levels in the water? We’re facing this issue here as well
There’s too much chlorine – is it because all the plate heat exchangers in your factory share the same circulating water? It’s likely that a leak in the brine heat exchanger is causing the chlorine level to be too high
Reply to 10# Cobra1987: Chloride ions should be present, as we use water supplied by a thermal power plant, and the water is treated with polyaluminum chloride. Thank you.