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Our sour water stripped is fed with Sour water from our hydrocracker unit with respectively 40 000 ppmw and 35 000 ppmw of NH3 and H2S content and a pH of 9. Typical Residual NH3 and H2S in stripped water are respectively in a range of 50 ppmw and 0.5 ppmw. We recently observed that residual NH3 content in stripped water incresaed up to 2000 ppmw while residual H2S remained at low normal value. No change noticed on operating conditions. We also noticed an increase of ammonia content in waste water from vaccum fractionnator overhead vacuum system in the same range (2000 ppmw).
We tried to incresase live steam to feed ratio with no subsequent result.
What could be possible cause and what could we do to solve this problem?
 
Answers
01/06/2014 A: Khaled Alqasem, Jordan Petroleum Refinery Co, khaled.alqasem@hotmail.com
Ammonia is the harder component to be removed, I think pH adjecement is required ex 10.5 , You should recheck stripping steam or reboiler steam quantity, otherwise trays fouling may occur.
29/05/2014 A: David Kujawski, Refinery Water Engineering & Associates Inc, dk@refinerywater.net
You could take some temporary interim measures to increase NH3 Removal Capacity in your central Wastewater Treatment Plant. These measures would not involve a capital project expansion. These measures would involve an Aeration Retrofit of one or a couple of small, unused storage tanks, even Baker Tanks. These measures could be fully functional in a week to 10 days. Aeration could start in a rudimentary fashion, and once accepted as a solution, an advanced system could be put in, cheap.
28/05/2014 A: Egbert van Hoorn, Hocon B V, Egbertvh@hotmail.com
The level of H2S and NH3 that you are mentioning in the water from your hydrocracker is high. This implies a significant risk for corrosion for the hydrocracker exchangers! More washwater should be injected!
The high residual NH3 content is possibly created by contamination with an acid. Contamination with and acid will fix NH3 and make it difficult to strip. This is very unusual for a hydrocracker, so it's perhaps linked to the source of the wash water or something else.