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We are currently having problem in debutanizer of our naphtha hydrotreater due to ammonium chloride deposition. However, we do not have online water wash and we do not want to shutdown our unit. We are thinking of injecting steam (while the unit is commissioned). Is onstream injection of steam in the debutanizer to remove the ammonium chloride deposition applicable and effective in a debutanizer? If yes, what are the parameters we can check to safely conduct this activity? If no, are there any other way in order to remove the ammonium chloride deposition without shutting down the unit?
 
Answers
11/06/2015 A: Narendra Naidu, Bapco, nbpnnaidu@gmail.com
In normal operation the Hydrotreater should not see any Chloride salts in the Debutanizer overheads, it should all be washed with Wash water at the Effluent exchangers and be dissolved in Sour water.
You may have some Ammonium bisulphide salts formation but the deposition temperature would be very low based on the concentration.
So in short if you have Chloride salt deposition in your debutanizer overhead than the problem exists in the sour water separation in the cold separator and there is physical carry over of Sour water with salts to the downstream oil. check and rectify that. Check the interface levels in the separators?
Where is the source of extra Chloride? some of the sources could be, check your Naphtha feed Chloride content has it increased? H2 make up Chloride content if this is coming from a Platformer? Stripper Sour water used as wash water in Hydrotreater chloride content?
05/06/2015 A: Narendra Naidu, Bapco, nbpnnaidu@gmail.com
Are you sure it is Ammonium Chloride? is it Ammonium Bi sulphide salts?
02/06/2015 A: Sarath Konda, DuPont India, sharathsatya@gmail.com
Water wash is the ideal way of removing Ammonium chloride salts deposition. Injecting of steam might alleviate the problem due to dew point of steam with unconverted HCL molecules forming corrosive HCL acid, whcih can chnage the pH of overhead water and increase overhead corrosion. Water wash shoudl help to flush out most of the ammonium salts. Ensure that wash water rate is enough to keep atleast 25 vol% of injected water in liquid form
13/05/2015 A: Berthold Otzisk, Kurita Europe GmbH, Berthold.Otzisk@kurita-water.com
Often ammonium salt fouling and corrosion is observed in the top section of a debutanizer, the overhead system and the reflux line. A continuous steam injection may help to remove ammonium salts, but the formation of an emulsion phase is a potential risk. Although ammonium salts are soluble in water, some salts will remain in the presence of hydrocarbons.
Kurita´s patented ACF technology is a very powerful alternative to avoid shutdowns. The abbreviation ACF primarily stands for Ammonium Chloride Free and the additives used for this technology are liquid formulations based on a very strong organic base. The ACF additives directly react with ammonium salts, which are converted into non-corrosive and non-depositing liquid components with a neutral pH. In case of severe corrosion it is possible to combine the ACF additives with a powerful filming amine to provide a perfect corrosion protection.
13/05/2015 A: Vineet Singh, IOCL Panipat Refinery, SINGHVK007@GMAIL.COM
We have experienced severe fouling FCC MF top section. On line water wash is very effective than steaming as NH4CL gets dissolved in water easily. Intermittent DM water injection through reflux Line may help.
12/05/2015 A: David Kujawski, Refinery Water Engineering & Associates Inc, dk@refinerywater.net
Injecting localized steam will increase the rate of NH4Cl deposition. You must carefully control the Dew Point Temperature to control deposition. You can slow down deposition with Amine Treatment, and should substitute Amines for NH3 feed.