ppm H2S IN WATER

[GabrieleB]

I have a produced water with 12 ppm of dissolved H2S. I have non idea of the partial pressure at the equilibrium condition (Required by ISO 15156). Considering this uncertainties, has anyones indicative values of H2S ppm dissolved in the water to be sure that Sour Servive Condition will not occur? What I know is that ussually < of 1 ppm is water considered without relevant H2S. But how may ppm give you the risk to be in the Sour Service Condition?

 

[SJones]

For liquid phase calculations, refer to Part 2 Annex C.2

How many ppm give you the risk to be in sour service condition?

Answer: Any above zero.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[GabrieleB]

I have already seen the Appendix C.2 of ISO 15156. To find molar fraction on gas phase I need to simulate the equilibrium condition to move from molar fraction in liquid phase to gas phase. It is possible, but is not immediate. I have seen also some standards that talk about H2S ppm in water phase and gives some general classification. For example where content is below 1 ppm, the water is considered with no significant H2S. For values above 1 ppm the H2S is considered non negligible. But wich is a reasonable value below that I can be sure that I'm not in Sour Service Condition. With 12 ppm of H2S can I consider save or not from Sour Service. I need an answer from someone that has confidence with this kind of numbers, this should be the quickest way to proceed. C.2 annex is not practical for a quick answer. Thanks in any case.

 

[SJones]

You need an answer from somebody who knows what they are doing and has professional indemnity insurance behind them. You don't need to simulate anything. Trace back to where the water was last in contact with gas and take it from there; or, get your process engineers to run a flash calculation to get you a gas phase H2S concentration. Look at the definition of sour service and you will find that there is no 'reasonable value below which you can be sure that you are not in sour service condition (sic).'

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.