Problem of excessive methanol acidity (waiting online; replies can be rated)
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This post was last edited by Registered User on 2009-5-18 22:09. The product contains 0.0002% formic acid, which goes directly into the storage tank; samples show around 0.002% formic acid. Please analyze what could be causing this and how it can be resolved
After reaching the storage tank, the temperature of methanol is 40–50 degrees, and the positive pressure from the nitrogen seal is normal
Reason for excessive acidity: Incomplete pre-removal. Is the condenser of the atmospheric pressure column at atmospheric pressure, and how is the pressure in this column regulated? Mainly, the light components have not been completely removed. The influencing factors include reflux temperature, reflux volume, bottom temperature of the tower, and feed composition.
The temperature of the refined alcohol in the intermediate tank area is 40 degrees Celsius. Is the temperature of the alcohol entering the tank 50 degrees Celsius? The cooling effect of the refined alcohol cooler isn’t very good.
Formic acid is a light component that should be removed in the pre-tower; other light components that are removed include carbon monoxide, carbon dioxide, hydrogen, dimethyl ether, and formic acid.
I think it’s due to the pre-tower; do you have additional extraction water there? It allows for the adjustment of the volatility of components, which facilitates the removal of light components, especially methanol azeotropes.
Haiyou, please reply. Could you tell me the operating parameters of your various towers? I'm very interested.
Hello, I wasn’t here just now. We use double-column distillation; the products pass the quality checks, but their acidity increases after being stored in the tank for some time
We are suspecting that the nitrogen sealing effect is not good, allowing oxygen to enter the storage tank; as a result, some of the methanol is oxidized to form formic acid, which leads to an increase in the formic acid content
So, can methanol be oxidized by oxygen at normal pressure and 50°C? It’s good to take it out of the tower; after being left there for a while, the acidity increases. Could it be that some complexes inside are breaking down? It’s so strange, waiting for an answer!
Personal opinion: Oxidation is unlikely; the reasons are flimsy. 1. First, ensure that the analysis is accurate. 2. Take samples from the top and bottom of the storage tank to check whether the acidity levels are the same. 3. Has this phenomenon been present all along, or did it just start appearing? Or did you just start operating the equipment?