Why is the acidic water in the reforming pre-hydrogenation stripping tower dark in color?
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The reforming unit has been in operation for 3 months. The corrosion inhibitor injected at the top of the pre-hydrogenation stripper is an oil-soluble type. However, after a shutdown of 2 days half a month ago and restart, the acidic water taken from the reflux tank at the top of the stripper was dark black in color; the amount of corrosion inhibitor injected remained unchanged, at around 3.6 PPm. Before the shutdown, the color of the acidic water was slightly dark, resembling gray. Has anyone encountered dark-colored acidic water at the top of a stripping tower? What could be the cause?
That’s because it turns black when it oxidizes.
It turns black as soon as it’s taken out – oxidation can’t be that fast, right? . . :o
Was it mixed with exhaust gas containing ethylene glycol before being taken?
Ethylene glycol? There is nothing like reformation in this process; the acidic water is taken from the water drum at the top of the stripping tower, without being mixed with any other gases.
Then it’s necessary to test what substances are contained inside in order to analyze the cause
I dried the acidic water, and there was a lot of yellow rust inside~ but I don’t know why it turned black?
Is there coked naphtha in the raw materials? Is the pressure drop in the pre-hydrogenation reactor constantly increasing? Measure the oxygen content of the raw material; it could also be char formed by oxidized olefins.
The raw materials are a small amount of hydrogenated gasoline produced from diesel hydrogenation and wax oil hydrogenation, along with most of it being straight-run naphtha; the pressure drop in the pre-hydrogenation reactor is very low and shows no tendency to increase~~
After represurfacing with a different corrosion inhibitor, the water is becoming clearer now. The iron ion level achieved today has dropped to 4.0 μg/l. :D
What was the amount of iron ions used originally? Is it a problem related to the quality of the corrosion inhibitor?