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Our refinery has installed corrosion control system (filming and neutralizing amine injection) in our overhead distillation column system. However, since the water content isn't too high, we cannot have enough sample from water bootleg. Our Fe content in water bootleg sample is quite high (>100 ppm) with previous injection of filming amine is considerably high (up to 18 ppm). The chemical vendor suggested us to install wash water system. However, install wash water system may take longer period and we wonder if continue injecting amine is still effective without wash water system. Have anyone had this kind of experience and is there any suggestion to keep the corosion controlled without wash water system?
 
Answers
09/04/2019 A: James Chacko, Suez Water Tecnologies & Solutions, james.chacko@suez.com
Our suggestions as follows
Of course, Iron indicates corrosion. However high Iron also indicates you have very less Water as- absolute quantity to flush down- available at boot drain point. We assume you have very little amount of stripping steam. If you have only minimal level of stripping steam, and unable to make hardware changes to water wash, what we suggest are below options
1. To apply a LoSalt type of chemistry suitable for application into stripping steam. Compliment with Filmer at 6 ppm. -Proactive
2. Apply LoSalt Chemistry suitable for overhead application and compliment with a filmer at 6 ppm max. Pro-active
3. Check Chloride level. If below apply a Combination Filmer at 12 ppm-Proactive
Targets no high Iron above, 3 ppm, No Salting above Water Dew Point. pH as 5.8-6.2 range. we have references and case studies to share. Further details can be shared on request
23/03/2019 A: Satyalal Chakravorty, Sr Consultant, satya1354@yahoo.co.in
No one operates the plant with such a high iron content. If you're injecting sour water in Desalter, please check its H2S level. Suggest to inject caustic solution for time being at upstream of Desalter to control Ph. Check for Ph overhead and Iron content.
14/03/2019 A: Berthold Otzisk, Kurita Europe GmbH, Berthold.Otzisk@kurita.eu
The reported Fe concentration is with 100 ppm appallingly very high and not a good indication for a suitable corrosion treatment programme. The recommendation to install a suitable water washing system is for sure a good idea. The injection of a neutralising amine increases the pH of the first droplets to reduce the corrosion potential during condensation. But the disadvantage of such neutralising amines is, that the formed neutralising amine chloride salts again are corrosive and can attack the metal surface.
A filming amine is a good option to provide a protection barrier between metal surface and acid compounds. About 18 ppm filming amine treat rate sounds also very high. It is possible, that the filming amine don´t works properly why Fe is still high. It could also happen, that because of that high treat rate (I guess you are using an oil-soluble filming amine) the filming amine shows dispersant properties and removes the natural FeS protection layer from the metal surface, why you analyse about 100 ppm Fe later. Try to Keep the Ph at about 5.5 to 6.5, if it is a CDU. The usage of neutralising amine plus filming amine is a standard at refinery process units.
Kurita´s patented ACF technology could be a perfect alternative, if you cannot install a water washing system within the next months. A very strong organic base - called ACF - is used, where the formed ACF-Cl salts have a neutral pH of 7 and show only a very low corrosion potential. ACF-Cl is highly hygroscopic and will stay liquid. When there is some water from steaming in the system that amount of water should be enough to keep the formed ACF-Cl salts liquid. ACF reacts immediately with chlorides and is able to replace the ammonia from NH4Cl deposits. So by using ACF you will significantly reduce the corrosion rate. The organic base ACF will be handled like a neutralising amine and can be used without problems together with a filming amine.