Hydrotreater sour water corrosion

[rscosta1976]

Dear all,

Please share your experience regarding REAC system corrosion as function of the separator water pH.

For NHT, UOP recommends to maintain a minimum of 3%vol wash water and to control the separator water pH between 5.5 and 6.5 (avoiding the 6.8 to 7.3 range).

1) What is you experience regarding the proposed pH target of 5.5 to 6.5 in NHT?

2) For DHT and especially for Hydrocracker units, due to the high amount of NH3, the sour water pH is generally higher. For these units, what is generally the optimal pH range for the sour water downstream of the REAC? How about the target for the wash water rate?


Your answers are very much appreciated.

Regards,

 

[DBreyer]

Check API RP 932-B: "Design, Materials, Fabrication, Operation, and Inspection Guidelines for Corrosion Control in Hydroprocessing Reactor Effluent Air Cooler (REAC) Systems". Lots of industry experience went into it and it is a good guideline for operating conditions

Daniel Breyer
Inspection Engineer

http://lnkd.in/dFcQA-w

 

[Chumpes]

Hi
more than pH range (why UOP asks for avoiding near neutral pH range 6.8-7.3 where corrosion is supposed to be slow ??), other parameters have large influence on expected corrosion rates of carbon steel in headrotreating units :
- intermittent/continuous wet/corrosive conditions
- flow regimes and possibility for water to effectively wet metallic surface
- distribution piping arrangement providing or not an even distribution in the heat exchanger
- pollutants such as HCl, ...

API RP 932B gives valuable guidelines for controlling corrosion by sour water, providing also guidance on wash water quality/composition