Corrosion issues in the MDEA decarboxylation process
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Our company uses the MDEA decarboxylation process; the facility was put into operation in 2000. During a major overhaul in 2007, it was found that the diameter-changing section of the absorption tower was severely damaged. To date, the cause of this corrosion has not been identified. I would like to ask experts: under what conditions does corrosion occur in the MDEA decarboxylation process? Have we checked that the solution composition is fine?
I’ve mentioned before that a company in Sichuan faced a similar situation regarding medium-nitrogen fertilizers, but I don’t have the electronic version.
In principle, no corrosion occurs; only a certain degree of cavitation is present. . . . . . You should check the flow rate issue in your system.
In general, high moisture content in solvents can easily lead to acidic corrosion.
We have built several sets of such devices, and this phenomenon generally does not occur. As for the reasons mentioned by the original poster, I have also read relevant reports; this phenomenon does occur in absorption towers, and the analysis of its causes is quite thorough – it is mainly due to cavitation and acidic corrosion, as the solution itself is not corrosive.
If the flow rate of the lean liquid is not high enough, or if the solution is not distributed properly, and the reduction zone is not wetted by the decarburization liquid, the rising gas contains carbon dioxide, leading to acidic corrosion in this area. The degradation products of the solution are also corrosive, but not only locally. Acidic corrosion is a likely possibility. Cavitation generally occurs at valves with severe throttling in semi-depleted or rich liquid conditions.
In addition to process-related reasons, equipment manufacturing quality and stress concentration may also be factors