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Foaming In Amine Unit


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#1 Alaa55

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Posted 31 October 2020 - 06:40 AM

Hello,

 

In our facility we have an acid removal unit to remove acid gases from gas. This unit manily consists of an absorber and regenerator columns and utilize Di-Glycol Amine solution (DGA) as a solvent. Fomaing is the main issue we are facing in this unit. My question is simple: Why when foaming occurs one of its symptoms is an increase of pressure in solven flash drum V-1504?

 

 

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#2 breizh

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Posted 31 October 2020 - 07:52 AM

Hi,

Consider the literature attached to support your work.

Hope this is helping you .

Breizh 

Attached Files



#3 Alaa55

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Posted 01 November 2020 - 04:54 AM

Thanks breizh for sharing these documents, I have read both of them but still can't find why pressure increase in flash drum whrn foaming occurs. The literature often list these symptoms for foaming:
 
• Fluctuating absorber or stripper ∆P
• Amine carryover from absorber, stripper or flash tank
• Swinging liquid levels in any vessel
• Decrease in H2S removal with increase in CO2 removal
• Off-specification treated gas
• Positive results from foam test
• Poorly stripped solvent
 
It says nothing about flash drum high pressure.


#4 AlertO

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Posted 03 November 2020 - 03:10 AM

Hi Alaa

 

i just wonder where is the flashed gas from V-1504 going to?

 

The unit is probably operated at high amine circulation rate (one of the factor promoting foaming) where the large amount of absorbed gas is released at flash drum. The high flow rate of the flashed gas can slightly build the pressure at V-1504 connected to a pressure of any downstream system.

 

Take care.



#5 Alaa55

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Posted 08 November 2020 - 03:48 PM

Hi AlertO,

 

The flashed gas from V-1504 is desposed of in flare or incinerator. Amine circulation rate is about 100 m3/hr. Normally the pressure in V-1504 is 4.5 barg. It only increases when there is foaming in the system as indicated by fluctuating absorber or stripper ∆P. In this situation, we inject antifoam and the pressure quickly decreases in V-1504.

 

Regards


Edited by Alaa55, 09 November 2020 - 06:05 AM.


#6 Technical Bard

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Posted 25 November 2020 - 04:39 PM

If the Absorber if foaming severely, you may be carrying gas bubbles out with the rich amine, which would significant increase the vapour flow from the Flash Drum.  The outlet valve may not be sized for that case.  This would explain the flash drum pressure increase.

 

The best thing to do is to keep the solvent clean (via filtration and reclaiming) and make sure the gas coming in doesn't contain heavy hydrocarbons that might condense in the absorber.  

 

I work for a firm that licenses DGA-based treating solutions.  Perhaps you need to contact us.






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