The acidic water at the top of the atmospheric pressure tower suddenly turned black
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The acidic water from the atmospheric tower in the vacuum distillation unit has always been normal in appearance, with a transparent color; however, it suddenly turned black some time ago. After sampling and leaving it for some time, its color returned to transparent, but the iron ion level was above the normal limit. What could be the reason?
There are problems with electrodialysis; the desalination is incomplete, and chloride ions reach the top of the tower, causing corrosion.
The corrosion at the top of the tower has worsened. Has there been any change in the crude oil composition during this period? If not, consider using additives at the tower top. Were the corrosion inhibitors and neutralizers not added properly?
Recently, there have been frequent changes in raw materials; the crude oil varieties are diverse, with a high sulfur content of around 1.5
Consider making adjustments to the additives. It is still likely that the corrosion of wet hydrogen sulfide at the top of the tower has worsened. Whether the tower top corrosion inhibitor model is compatible. The pH value can be adjusted using a neutralizing agent, and this can be observed through on-site sampling. However, if the type of corrosion inhibitor is not compatible, problems are likely to arise.
We have been using a certain type of neutralizing corrosion inhibitor here; there are no other variants available
With such corrosion, it will become severe in just a month or so. Check the thickness of the elbow areas more frequently; if there is no online thickness measurement, conduct several additional temporary manual thickness measurements. Regarding additives, it’s worth considering whether to switch to a different model; there are many good suppliers of additives available. Another point is that water injection at the top of the tower is also very important – are you injecting enough water? Should the water injection point be at the top of the tower or at the inlet of the heat exchanger?
With such corrosion, it will become severe in just a month or so. Check the thickness of the elbow areas more frequently; if there is no online thickness measurement, conduct several additional temporary manual thickness measurements. Regarding additives, it’s worth considering whether to switch to a different model; there are many good suppliers of additives available. Another point is that water injection at the top of the tower is also very important – are you injecting enough water? Should the water injection point be at the top of the tower or at the inlet of the heat exchanger?
The water injection point is at the tower top distillate, with a water injection volume of around 2300 kg
Corrosion at the top of the atmospheric pressure tower is severe; first, control the level of salts in the electrodialysis process. If the properties of the crude oil worsen, it becomes impossible to remove the salts, in which case more corrosion inhibitors should be used to keep the pH level above 7, as well as to control the amount of iron ions present. Some time ago, due to the poor quality of crude oil, there were over 300 iron ions in our facility; as a result, the elbows of the long-top heat exchanger corroded and perforated, so they had to be removed for repair