When to use Heated 3 phase separator or Nonheated 3 phase separator?

[maengineering]

Im needing to decide from a cost and efficiency stand point if a heated or non heated separator is the best decision. The design is basically a multiple well head process that has already gone through a 2 phase separation. Temp in 2 phase stage is roughly 180 and dropping to roughly 90 degrees prior to entering this part of the process (3 phase separator). Basically, when is it necessary to use a heater treater or free water knockout? Those are basically the options right? Free water knockout is just an unheated separator that is sometimes followed by a heater treater from my understanding. I have some design conditions if needed, but the main question is when would a heated be better than a non-heated and why? Thank you all so much!

 

[1503-44]

Basically the same reason that you wash your hands and clothes in hot water. The water is less viscous and washes the dirt out faster and easier than using cold water will. Fluids with higher viscosities (usually those at lower temperatures) are more difficult to separate. Look at how viscosity of water, your oil components and your gas mixture are affected by temperature and the length of time and distance needed for separation. Applying heat can shorten the time and distance, making for smaller vessels and faster flow rates.

Foaming might also influence the separation process, so take that into consideration as needed.

 

[maengineering]

Thank you for the response. I will look into those variables and changes. Would you recommend using the GPSA book or is there a better place with that info? Also, if a heated separator is used, that would likely require a cooling device prior to the gas going to the final line correct?

 

[1503-44]

Yeah, GSPA has some on that. We did some questions on that a week or two ago too. Link follows.

You will need to get the temperature allowable on that pipeline. It might depend on the design code, pipe stress, or its coating. Normally you should target 100-120F or less for pipeline delivery, unless the pipeline has been designed specifically for hot oil or gas.

See

https://www.eng-tips.com/viewthread.cfm?qid=485802

Especially (This link doesn't seem to work now.) now it is again.

http://acreditacion.uni.edu.pe/wp-c...-Gas-Separators-–-From-Hydrocarbon-Stream.pdf

And a few other links there.