10 replies to this topic

[Ghasem.Bashiri]

I have a problem in our Gas Sweetening Plant as follow:
During summer our Rich Amine Flash Drum with a packed bed at top of it (that uses a portion of lean amine to treat flashed gas from amine flash drum) can work properly. Therefore outlet gas from flash drum is suitable as Fuel Gas. However during winter that our plant works at full capacity we have considerable Foaming if mentioned packed bed of amine flash drum become in operation. Therefore we should reject flashed gas to flare because we cannot treat it with side stream lean amine in packed bed on flash drum. Do you have any experience for this item? For your information during summer we work with some turn down and lean amine is 5°C warmer than inlet gas however during winter lean amine temperature is only 1-2°C warmer than inlet gas? Is our problem solely belonging to temperature of our lean amine and its gap with inlet gas temperature or other item should be checked? Our MDEA concentration is 45% wt.
Ghasem.Bashiri
Ghasem.Bashiri@gmail.com

[rosa]

Hi;

there is some troubleshooting for foaming.


1)Keep amine temperature 5-10ºC above the inlet gas temperature.
2)Check the DP of absorber,if it is high:
3)Reduce the circulating amine flow but increase the amine flow to the filteration package.
4)Increase the Anti-foam injection rate.
5)Check the flash gas flow rate.If it has high flactuation then,
6)Check the absorber level that any HC/amine interface is observed if yes go to 3) stage.
7)Check the DP of filters in amine filteration package
8)Check the opening of Treated gas K.O drum's LV.If it has flactuation check foaming and do the skimming.
9)Keep reboiler temperature less than 140ºC because amine degradation in high temperature develop foaming.
10)If the H2S of sweet gas is still high first decreas the inlet sour gas flow to absorber(as the short-Term action)

[Ghasem.Bashiri]

Dear Rosa
If you refer to my topic, you see that I have not problem in Summer condition.
Foaming happen during winter with maximum gas rate.
Also foaming happen if Lean amine to Flash Drum become in opration.
If I stop flashed gas sweetening I have not any foaming problem.
Best Regards
Ghasem.Bashiri@gmail.com

[sandeep chk]

Hi Ghasim,
I think the foaming may be ralated to the gas rate and not the temperature. If posible reduce the gas rate in winter and check for foaming.
Sandeep

[Ghasem.Bashiri]

Dear Sir, Madam
I need peak rate of Amine during Winter to meet requirement of network.
Therefore I should produce gas at maximum rate.
What is your proposal in this condition.
A.Bashiri

[aanita]

Dear Sir, Madam
I need peak rate of Amine during Winter to meet requirement of network.
Therefore I should produce gas at maximum rate.
What is your proposal in this condition.
A.Bashiri

Amine temperature should be more than 5 deg.C higher than sour gas, otherwise amine will gain
heat from sour gas and some hydrocarbon will condense , start foaming.
Any problem if you increase amine temperature?
Optimize amine circulation also.
There is thumb rule to calculate optimum amine circulation.

Regards.

[amdady]

hi Ghasem;

did you find any solution for your problem?

because we are facing the same problem now; we have foaming in the amine flash drum and i don't know how to reduce it; the level of the HC side becom full after certien of time because of this foaming; sample had been taken to be sure that the level accumelated is rich amine not HC.

did you reduce the level in the amine flash drum? or you increase antifoam concentration? may i know please what did you do?

[aanita]

Foaming is a common phenomenon in gas sweetening using MDEA system contactor, however in flash drum it is very rare. we have foaming in MDEA contactor when plant load is more than 110%. surprisingly recently we stop antifoam dosing , which was running continuously and getting foaming occasionaly. At higher load we still not face foaming in flash drum or regenarator, except contactor. And when we face foaming , giving a shock dosing of antifoam till foaming under control. Even contactor foaming is not continuous , only when upstream load suddenly increase. We have a very good MDEA filtration system which I believe also reduce the foaming tendency.
I believe in MDEA system coninuous dosing of antifoam is required .
I am also eagerly waiting for Ghasem reply what he did to prevent foaming in flash drum. one difference I see while Ghasem face foaming in WINTER , Amdady face in summer time when ambient temperature is high.
Amdady can you share your foaming phenomena details and operating parameters. You should maintain gas temperature more than 5 deg C , possiblely 8/9 Deg.C, and continuous dosing of antifoam. Waiting for your reply.

Regards.

[amdady]

Welcome again;
The gas temperature is vary between 80 to 90 F depends on ambient temperature; While lean amine temperature is 135 F. we are trying to control the gas Temp between 80-85 F because we notice that once the temperature increased we face a foaming in the amine contactor.

We just finished the first T&I on gas sweetening unit; before the T&I the foaming used to be like a habit in sour gas processing unit; We found huge amount of slugs inside the amine contactor; amine flash drum; trim cooler and exchangers. We clean out the system and return the unit back to service but we isolate amine filtration system because we found there was carbon immigration from the carbon bed passing through the guard filter to the amine system. We used to add direct batch of the antifoam but this step become useless; so we reduce the rate to 150 MMSCFD (design rate 385).
After cleaning; the unit back on line before 3 weeks; everything is normal except the foaming in the amine flash drum. We are thinking now to return the carbon filter on line in order to reduce the amount of solids in the amine inventory.
The anti foam dosage is continues in our system.
By the way what type of filtration you are using for the amine; (I mean the carbon bed)

[aanita]

15% of total amine circulation is being filtrated. The main filtraion ( flow : 115 m3/hr) is cellulose filter followed by a split flow(35 m3/hr) passing through a charcoal bed (carbon filter)and join to the guard filter and finally go to the amine storage tank. ( Type of charcoal be name I don't know).
we never keep out of service charcoal filter, if guard filter need to by -pass, then carbon filter also to be by-pass.
Is foaming in flash drum is continuous or occasionally? Gas temperature is quite low( 80F =27 Deg.C). you mention sludges in contactor, flash drum, cooler which are may be the one reason of foaming . However at 130% of plant load we didn't face any foaming in flash drum.
You should put back on-line carbon filter with guard filter .
Keep us update your parameters.
Still I am waiting for GHASEM reply.

Regards.

[amdady]

I knew that we shouldn't put the carbon filer out of service; but we thought there is something wrong with the bottom mesh. As I told you we have seen carbon migration within the system that's why we bypass the filtration system.

The filter now is online; it is guarded by 2 filter upstream filter 5 micron and down stream filter 1 micron. I told them yesterday to cut the rate and run the unit on hot circulation mode after washing the carbon by RO water and make sure there is no more carbon fines. The foaming tendency now becomes better than before. I know it will take few days to filter whole amine inventory, but what surprising me the guard filters were blocked after 2 h of circulation which tell there is solids contaminated in our system. We are now trying to filter the system as much as we can.

You mentioned the amine goes from the carbon filter to amine storage tank!! In our plant almost 25 % of designed circulation rate is filtered then it combined with the rest of amine going to amine contactor.

The foaming in amine flash drum is continues after planed T&I. in the past we used to have it in the amine contactor but nowadays only in the flash drum. The levels are flying with flashed gas. We have a lot of MDEA losses.

By the way this is the first time we experienced this kind of foaming I mean in the amine flash drum.

regards