10 replies to this topic

[Paktongkoi]

Dear All,
There is a CO2 absorber column in our plant, removing CO2 from the feed gas.
Few months ago there was foaming reported at the packing, which in return, operation cannot maximize the Co2 removal process. It is suspected that the packing (stainless steel pall ring) were contaminated. One of the suggestion is to take out those packing, and have it cleaned before putting it back into the column.
Any of you have done similar job before? How do you do the cleaning?

[Zauberberg]

How can you be so sure that fouling is the culprit of absorber malfunction? What are the symptoms? Have you observed anything else, apart from off-spec product or reduced plant throughput?

Usually, these systems are washed by the circulation of chemical solvent in a closed-loop system (after shutdown and isolation, of course). You can contact your chemical suppliers and ask for an appropriate cleaning agent. Chemical solvent circulation is applied before tower opening for inspection and maintenance works.

Depending on the degree of fouling/damage, you may consider replacement of Pall rings, and they are (usually) available in your spare parts storage. Chemical washing is the most effective way of cleaning structured or random packing, and I believe it's the most common practice in many industries.

Before all that, be 100% sure that fouling is the reason why you are shutting the plant down. Otherwise, it might come out that you are wasting your time for nothing.

Good luck,

[Padmakar Katre]

Dear,
Could you please tell me what is the solvent which is used for CO2 absorption. Is it amine or K2CO3 so that I could comment specifically.

[Paktongkoi]

Dear Padmakar,

it is K2CO3.

[Padmakar Katre]

Dear,
Along with the information you have provided I want to know the feed gas conditions like gas rate and the intial CO2 content as well othe major componets with theere composition %. The solvent circulation rate and the K2CO3 conc.or the carbonate/bicarbonate ratio in the last one weeks sample analysis. Because backed up by the similar experiance I have experience the poor CO2 removal rates because of the other conditions that the packings contaminations as the MOC of the packing
is SS304 and provided that your carbonate conc. doesn't exceed 25% v/v no need to worry about the packing contamination. Just there are other reasons which I will tell based on your data. Waiting for your comments.

[Paktongkoi]

Dear Padmakar,
It is actually hard for me to answer that question since I'm in maintenance dept.
I will try to get the answer from my operation friends.
Anyhow is there any general cleaning method in order to clean the packing from contamination? We plan to use demin water to clean them.

[Padmakar Katre]

Dear,

You can have hot water run in the system. But for that you need to shut down your unit. If the cleaning of packings is done within less than one year then my advice to you is to furnish the data which I need to analyse so that I can put the probable reasons why CO2 recovery is less in the unit. If you are talking about the EO-EG unit, then leave it to me. I can give you the right solution on how to increase the CO2 removal section efficiency. Waiting to see the data from your side.

[Qalander (Chem)]

Dear Paktongkoi hello/Good morning,

May i suggest my little bit.

Firstly; a decision to withdrawal from service for few days period.

Secondly; if no vendor's restriction then dilute acetic acid/citric acid warm solutions soaking a few days
thereafter; hot water flushing to remove acidic/liquids and dissolved materials if any till cleaned.

hope this might be helpful.
Regards
Qalander

[Paktongkoi]

Dear Padmakar:

The problem happened after inspection work last year. During that inspection, we only opened the manhole and checked the integrity of the distributor, the bed support etc. No cleaning was done that time. The packing was not cleaned during the last 5-6 years.

After the problem happened, we have done steaming and circulated demin water for a few days. The problem was reduced but is not solved completely. That's why we are planning on cleaning the packing out side of the column (need to unload the packing).

Anyway, I still have not obtained the info you needed. Maybe I'll have it in a few more days.

Dear Qalander:
Will bring your ideas to the team to consider. TQ.

[Paktongkoi]

Dear Padmakar;
The followings are the feedback from operation people:

1) Feed gas rate: 300 t/hr, pressure 70 bar, and temperature around 27 degC.

2) Solvent Circulation: 550 to 600 m3/hr

3) K2CO3 conc: 26%, carbonate/bicarbonate: 0.2

4) Initial CO2 content: 5 - 7 mol%

5) Major feed gas components (mol%):

N2 = 0.39
CO2 = 5.16
C1 = 81.05
C2 = 6.91
C3 = 3.32
iC4 = 1.08
nC4 = 0.73
iC5 = 0.38
nC5 = 0.2
C6+ = 0.78
Total = 100.0

MW: 21.07 g/mol
SG: 0.7295
Density: 0.894 kg/sm3
GCV; 42.83 MJ/SM3

[Satyajit]

Hi Paktongkoi,
Is your CO2 absorption system problem is solved; Do you still face foaming problem.
Please give an update.
Kind regards,
Satyajit

Edited by Satyajit, 16 October 2009 - 02:10 AM.