The iron ion level at the top of the atmospheric pressure tower remains high – it’s urgent! Process: The crude oil enters the atmospheric pressure unit without electrical desalting, and then exits from that unit...
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The crude oil enters the atmospheric pressure unit directly, without passing through an electrodesalting unit or a primary distillation tower. Water and water-soluble neutralizing and corrosion-inhibiting agents are added to the vapor line at the top of the tower. Moreover, the crude oil is replaced every three weeks or so, with each batch having different sulfur content and acid value. It’s been two months, and the iron ion level has remained around 12 or 13. I’m looking for ways to reduce this level and slow down corrosion! It’s urgent! (Processing capacity: 100 tons/hour ； Dosage of water-soluble neutralizing and corrosion-inhibiting agent: 100PPM; water injection at the tower top: 70 tons per hour;） ； How to add neutralizing and slow-release agents when the water turns black frequently?
Have the raw materials been tested? Why is electrodialysis not used? If the raw materials are fine, then the injection volume should be increased further
Thank you for your reply. There is a problem with the electrodialysis unit; it won’t start. The maximum flow rate of the metering pump for the additive is 10 L/h, which is already the maximum value. The water samples collected now already show emulsification.
The raw oil has a low acid value but a high sulfur content
The processing capacity is 100 tons, with a water injection volume of 70 tons – that’s way too much. This invisibly increases the load on the top of the tower. I think increasing the concentration of the corrosion inhibitor injection would help.
High sulfur content! Has the iron content in the crude oil been tested already? It’s abnormal for it to remain at such a high level all the time
Thank you for your reply! We change the oil every two weeks or so; each time we do this, the iron ion level rises to around 20, and this condition persists for 3 or 4 days, accompanied by dark-colored water. Trying to increase the concentration of the corrosion inhibitor had no significant effect; the iron ion level remained around 12 or 13 (our testing method involves sulfosalicylic acid and a spectrophotometer at a wavelength of 520)
Thank you for your reply! The iron ions in the crude oil have not been tested; I don’t understand what it means that \"their level remains so high all the time, which is abnormal\". Could you explain it in more detail? Thank you!
The most fundamental reason is the frequent changes in crude oil; each corrosion inhibitor is developed by testing and formulating it specifically for a certain type of crude oil. Moreover, there is a pre-coating process after the change, so stability is generally achieved after 3 to 4 days. The solution is to reduce the frequency of crude oil changes, understand the characteristics of each type of crude oil, and add appropriate corrosion inhibitors.
No matter how the raw materials change, the iron ion level remains so high – that doesn’t seem right, does it? Test the iron ion level
What is the pH value? Is ammonia available? What you’re doing is very dangerous; first, keep the pH level between 7 and 9, increase the amount of corrosion inhibitor added, and re-establish a pre-film at the top of the tower. What are the salt content, acid value, and sulfur content of your raw materials? The electrodialysis system should be turned on.