On the corrosion issue of methanol-water separation towers
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Recently, there was a corrosion-induced leak in the inlet pipeline of the methanol-water separation tower at our facility; it’s not clear whether this is due to issues with the project quality or problems inherent in the process itself. This pipeline carries methanol-water mixture that comes out of the CO2 scrubber, is heated in a heat exchanger, and then enters the methanol-water separation tower. The pipeline section before the flange, prior to entering the tower, is made entirely of stainless steel; the leaking section is the short pipe connected to the tower body behind the flange, and its material is carbon steel (the exact type is unknown). I would like to ask those with experience: have you been involved in the maintenance of methanol water towers? Is there any corrosion inside the tower, especially at the inlet of these pipelines?
I have worked on several projects, and such a problem has never occurred before. Moreover, the pipes used are made of carbon steel, and there has been no corrosion either. Could it be a problem with the quality of the work?
I’m aware of a company in a similar situation to yours; the problem is caused by H2S in your exhaust gases, which leads to corrosion. There are two solutions: one is to stop recovering methanol and instead vent the exhaust gases directly (if the pressure permits); the other option is to ensure that the liquid entering the exhaust gas scrubber doesn’t flow directly into the tower, but rather along the tower wall toward the distributor. I recommend adopting the spray-type approach. If there are better ways, please suggest them! !