4 replies to this topic

[Ali_gholamalian]

Hey all

Is it necessary to maintain Lean TEG temperature higher than inlet wet gas?

As I remember, Lean TEG temp. is about 10 delicious degree higher than Wet Gas, but recently I faced a unit in that wet gas temp is higher than TEG. Is it a malfunction?

Thanks for your attention

[Bobby Strain]

The reason to maintain TEG inlet higher than inlet gas is to avoid hydrocarbon condensation. Most units have an interchanger to cool TEG with dehydrated gas so TEG temperature is always higher than inlet gas temperature. With lean gas, condensation may not be a problem.

 

Bobby

[Art Montemayor]

Ali:

 

If you are a chemical engineer, you will understand and appreciate the fact that if your humid feed gas to the TEG absorber contains relatively high molecular weight (and consequently potential condensables) hydrocarbons mixed in the natural gas (methane), you will have problems if your lean TEG is cooler than the incoming feed gas: you may have some hydrocarbons condensing and mixing with the rich TEG at the absorber sump and eventually making it into the regeneration unit and causing problems there and in the circulating TEG solution.  You don’t want or need that.

 

I am not familiar with delicious degrees, but if you mean 10 ^oC, that is not delicious, but thoroughly distasteful.  I’ve never seen a need to operate that high a temperature over the inlet feed gas.  The feed gas should be normally coming in at ambient temperature - or cooler, if possible.  But having said that, it all depends on your feed gas makeup and composition.  I am used to almost pure natural gas, and not rich associated gas with a lot of propanes, butanes, etc.  So it depends on your gas quality or source.

 

You don’t give your feed gas composition, so we can’t even guess from experience what a normal lean TEG solution temperature should be to ensure maximum, efficient dehydration.

[sargon 1979]

Ali,
If you have a heat exchanger ahead of the contactor column then try to check it. However, the inlet gas temperature reflects the saturation water content of the inlet gas which increases as the temperaure increases so, any increase in inlet temperature will overload the column.

[breizh]

Ali ,

you may consider this document :  http://www.refiningonline.com/ABPG_KB/

 hope this helps

 

Breizh