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Lean Teg Temperature Enter To Contactor


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#1 Wizgal

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Posted 05 April 2013 - 01:11 AM

Hi I would like to ask ,whether the temperature of Lean TEG enter to contactor play a significant role to the moisture outlet for dehydration process? Then what is the suggestion range of Lean TEG temperature above the gas temperature?. should be 10-15 degree F above gas? 



#2 shan

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Posted 05 April 2013 - 06:49 AM

TEG purity plays a significant rule to gas moisture content not inlet temperature.  TEG inlet temperature 5 F above gas temperature is a good number because 10-15 F above gas temperature may increase your TEG lose.



#3 Art Montemayor

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Posted 05 April 2013 - 10:57 AM

  

Shan is partially correct.  The Lean TEG moisture content (“purity) is – to a large extent – the factor that determines the ultimate product gas moisture content (“dew point”).  However, bear in mind that the warmer the product gas is, the more water moisture it is prone to pick up.  That is why it is wise to operate your contactor as cool as you can justify within the range of your process conditions.  The colder your process gas and lean TEG are, the lower the product gas dew point – BUT always within the reasonable limits of your process.  For example, the “heavies” content (propane, butane, etc.) in your feed gas is what practically puts a low temperature limit on your lean TEG in order to avoid condensing these out within the contactor and allowing them to mix with the rich TEG in the sump of the contactor and be allowed to enter the regeneration stripper and reboiler where they can cause havoc.  That is the reason for applying a +5 oC on the inlet lean TEG to the contactor.  This means you should keep your inlet lean TEG 5 oC above your inlet feed gas temperature – at the least.

 

As shan indicates, this guideline has nothing to do with controlling the final product gas dew point (although, as I point out it could affect your dew point if taken to higher levels).



#4 Wizgal

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Posted 07 April 2013 - 09:09 AM

Thank you for the answer. However i am still curious about the dried gas ..The temperature of dehydrated gas should b warmer or cooler ?..



#5 gazepdapi1

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Posted 08 April 2013 - 11:00 PM

Wizgal:

 

The temperature of the dried gas will be pretty much the same. Remember, the amount of gas compared to TEG coming into the contactor is very large. Although the glycol should come in a few degrees hotter, it quickly equalizes to the temperature of the gas. Therefore, the glycol temperature will not affect the dry gas leaving the contactor.



#6 Wizgal

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Posted 08 April 2013 - 11:24 PM

What if the Lean TEG enter the contactor very much hotter than the gas enter to the contactor?.. Approximately 30 F hotter than the gas inlet temperature.



#7 gazepdapi1

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Posted 09 April 2013 - 07:25 AM

This will tend to decrease efficiency and increase carryover losses but your contactor should have a mist extractor that should coalesce TEG droplet and reduce carryover. 



#8 Lai.CY

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Posted 18 April 2013 - 08:54 PM

Hello Wizgal,

 

Although it is not at boiling state, molecules at a liquid surface will still transfer to gas through convection. The warmer the lean glycol is, the higher the kinetic energy, the higher the liquid molecules vibrate, and liquid molecules will be knock on each other and out to the gas phase. Hence, more glycol losses into the gas phase.

 

Also, typically the lean glycol temperature is slightly higher than the gas inlet temperature is to avoid retrogade condensation. This you need to refer to the phase envelope.

 

Nertil1, I am not too comfortable with mist mats, because glycols are creepy liquids. And glycols have the ability to creep through mist mats and still be carried over as losses. I am not saying that mist mats are not applicable, and I know it's a typical design everywhere. So, what I prefer is a cyclone bundle downstream (say compressor scrubber) and route all the liquids back to the TEG Regeneration Flash Vessel. Let's not talk about this, since it is not related to the topic of the forum.



#9 gazepdapi1

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Posted 25 May 2013 - 10:07 PM

Weiiskruez:

 

I agree with your comment but typically we will spec a co-knit wire mesh instead of a regular wire mesh since TEG will wet stainless.  This will reduce carryover. My concern with routing all the liquids back to the flash tank is there will be water with this glycol and this would add additional load to the reboiler in case of a carry over.  Plus, since the outlet scrubber is well above the flash tank pressure, there will be some pressure control device to regulate pressure and prevent over pressuring the flash tank.



#10 trinhduchanh

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Posted 23 August 2014 - 09:36 PM

Dear All,

 

As i known normal practice then temperature of Lean TEG always design higher +5oC with inlet feed gas from dehydration inlet scrubber. When i refer to some book and previous project document then it is same design with that. But now we are working with new project have  a glycol system with different design. Vendor utilized temperatue from outlet gas glycol contactor below lean TEG temperature inlet gas +5oinstead for using inlet gas temperature to control TEG temperature inject to gycol contactor. As per my undertanding if they use reference point from gas outlet then margin of lean TEG with gas inlet will be more than +5oC as i assume that it around 7 to 8 oC. If inlet glycol tempeatures greater than 10oC above the gas inlet temperature result in high glycol losses to gas. Any body have experience with that design can you help me explain why vendor  must design glycol system such that  so it's have more advantages than compared with traditional designs?

   

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#11 GuyBartle

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Posted 30 September 2015 - 05:13 AM

I'd be interested to hear from anyone who has used a structured packed bed contactor as opposed to Tray type, I've experienced trays but not structured packed bed. Which is more efficient, are losses comparable, operating procedures similar, inspection intervals same, water draw off methods?

any info would be great :)



#12 Zauberberg

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Posted 30 September 2015 - 07:28 AM

Please start a new topic. This thread is more than 1 year old.






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