The issue of injecting corrosion inhibitors at the top of the atmospheric and vacuum distillation tower!

The amount of corrosion inhibitor added is primarily controlled based on the acid value of the oil; it is around 70 ppm before film formation, and it drops to around 20 ppm after film formation, which is considered optimal. If the injection amount is too large, the consumption of corrosion inhibitors increases and production costs rise; however, it should not have a significant impact on the properties of the oil.

Using too much of the slow-release agent should have no negative effect on corrosion prevention; it’s just a waste of cost. If too much of certain slow-release agents is used, it can cause regular gasoline to turn yellow.

Currently, the corrosion inhibitors used at the top of the tower are primarily in the form of adsorption membranes. Adding too much of them not only increases costs but also causes emulsification of the sulfur-containing wastewater at the tower top (oil in the water leads to increased losses of light oil from the tower, while water in the oil can affect subsequent processing equipment).

1. Two-stage corrosion inhibitors are widely used to prevent corrosion at the tower top. 2. The amount used should not be excessive; corrosion inhibitors are inherently surface-polar substances that tend to cause emulsification, leading to oil loss.

Note that the amount of corrosion inhibitor used should be appropriate; in fact, many operations in oil refining require finding the right balance – it cannot be too much nor too little, and a proper equilibrium needs to be achieved to facilitate corrosion prevention, reduce costs, and ensure smooth operation.

It should have little impact on product quality.

1. Increase reagent consumption. 2. Corrosion inhibitors possess strong surface activity, which can easily lead to the formation of an emulsion layer at the interface between oil and water, affecting product quality and operational efficiency (as mechanical impurities in platinum become unacceptable). 3. When the top reflux contains a large amount of corrosion inhibitors, they will deposit on the top trays, causing the floating valves to stick and severely affecting the long-term operation of the plant.

First, I’ll like the reply from the 8th floor – it’s well said. In my opinion: 1. How do you know whether the amount of slow-release agent used is too much or too little? This requires you to have monitoring methods – it’s not just about checking the iron ions and the pH level of water; is there any testing for chloride ions as well? If possible, weak acid testing should also be conducted. Are there any probes or sensors on site that can provide data for reference? Corrosion at the top of atmospheric and vacuum distillation towers is primarily related to the control of dew point corrosion; factors such as operational stability and the amount of water injected are also very important. 2. Judging from the owner’s description, it seems to be a ‘neutralizing type slow-release agent’ commonly used in China; typically, the neutralizing amine used to neutralize HCl is combined with the film-forming amine, which makes it more convenient to use. However, in terms of controlling specificity, the flexibility of adding them separately is a bit lower. Too much neutralizing amine may cause salt formation (before the dew point) ； Using too much film-forming amine improves control over corrosion by weak acids, but it tends to cause emulsification (as described by a few people above). It is not easy to adjust composite slow-release agents; generally, control of dew point corrosion (or strong acid corrosion) is the primary concern, while whether emulsification occurs is a secondary issue.

I have a question: how long does it take for the corrosion inhibitor to form a film from the moment it is injected?