Benfield Foaming Issue
Started by hazree, Dec 27 2011 03:29 AM
benfield gas processing foam contaminant hydrocarbon gas
9 replies to this topic
Share this topic:
#1 
- Members
- 4 posts
Brand New Member
Posted 27 December 2011 - 03:29 AM
Dear all,
I have benfield unit in my plant to remove CO2 from hydrocarbon gas from offshore. Recently, the unit has been experiencing foaming and we are yet unsure of the reason.
The unit has one side stream mechanical filter to remove particulates (spec:10 microns) and has been clogging and needs to be replaced frequently lately which caused wonder among the engineers due to low total suspended solid (below 30ppm) in the system based on lab analysis. We dont have activated carbon installed yet.
Here are my questions.
1) Can the clogging be caused by other than solid particulates i.e antifoam (we use Unicorn) which we quite frequently injected in the system nowdays.
2)what are good analysis to determine if there is heavy hydrocarbon trapped in the system that may cause foaming?( currently we are using Total organic Compound(TOC) & oil and grease)
3)Can corrosion inhibitor from offshore caused foaming?
4)Can anyone share any good laboratory that can analyze benfield composition in order to nail the culprit of the foaming.
Thanks in advance
I have benfield unit in my plant to remove CO2 from hydrocarbon gas from offshore. Recently, the unit has been experiencing foaming and we are yet unsure of the reason.
The unit has one side stream mechanical filter to remove particulates (spec:10 microns) and has been clogging and needs to be replaced frequently lately which caused wonder among the engineers due to low total suspended solid (below 30ppm) in the system based on lab analysis. We dont have activated carbon installed yet.
Here are my questions.
1) Can the clogging be caused by other than solid particulates i.e antifoam (we use Unicorn) which we quite frequently injected in the system nowdays.
2)what are good analysis to determine if there is heavy hydrocarbon trapped in the system that may cause foaming?( currently we are using Total organic Compound(TOC) & oil and grease)
3)Can corrosion inhibitor from offshore caused foaming?
4)Can anyone share any good laboratory that can analyze benfield composition in order to nail the culprit of the foaming.
Thanks in advance
#2
- Members
- 119 posts
Gold Member
Posted 27 December 2011 - 03:39 AM
Hello Hazree
One point to watch out for with regard to using anti-foam. Apparently if one adds too much, or perhaps if it builds up in a system, it can have the opposite effect intended and cause foaming.
Dazzler
One point to watch out for with regard to using anti-foam. Apparently if one adds too much, or perhaps if it builds up in a system, it can have the opposite effect intended and cause foaming.
Dazzler
#3
- Members
- 4 posts
Brand New Member
Posted 27 December 2011 - 03:44 AM
Dazzler,
How one determine when it is too much
#4
- Members
- 15 posts
Junior Member
Posted 27 December 2011 - 05:14 AM
Hi Hazree,
Here are some of my thoughts :-
A high concentration of anti-corrosive additive which is a surfactant may cause the foaming. The problem may be exacerbated by having a packed tower which has too many internals. One question is which of the columns is foaming or are they both foaming.
One thing to note is that if you cooled the system without purging the CO2 then you would get a carbonate precipitate which would require heating and high recirculation to redissolve. If your internals are clogged, then of course you would get higher than design velocities of liquid through the tower. Have you measured your total carbonates ?
I hope this helped.
Best regards
Here are some of my thoughts :-
A high concentration of anti-corrosive additive which is a surfactant may cause the foaming. The problem may be exacerbated by having a packed tower which has too many internals. One question is which of the columns is foaming or are they both foaming.
One thing to note is that if you cooled the system without purging the CO2 then you would get a carbonate precipitate which would require heating and high recirculation to redissolve. If your internals are clogged, then of course you would get higher than design velocities of liquid through the tower. Have you measured your total carbonates ?
I hope this helped.
Best regards
#5
- Members
- 119 posts
Gold Member
Posted 27 December 2011 - 03:15 PM
Hazree
You asked about how to know how much anti-foam is too much. This will depend on the chemical and the system it is added to. It would be best to discuss this with your antifoam supplier company. The supplier should be able to tell you all about using of their chemical. You may even have an employee internal to your comany that is managing the dosing chemical vendors.
Dazzler
You asked about how to know how much anti-foam is too much. This will depend on the chemical and the system it is added to. It would be best to discuss this with your antifoam supplier company. The supplier should be able to tell you all about using of their chemical. You may even have an employee internal to your comany that is managing the dosing chemical vendors.
Dazzler
#6
- Members
- 4 posts
Brand New Member
Posted 27 December 2011 - 10:32 PM
Eman3001,
Only the absorber is foaming.
if I my understanding is correct, clogegd internal may excerbate foaming although foam height is within acceptable level. In our case the foam height clearly shows beyond acceptable level which I think may indicate contaminant like dissolved hydrocarbon or something else.
The solution is not being cooled, so carbonate precipitation is minimal plus we have mechanical filter to remove particulates.
Thanks.
#7
- Members
- 79 posts
Gold Member
Posted 20 January 2013 - 06:51 AM
Dear all
Good day!
I would recommend to at least share your PFD , current operating data so that our friends can access the actual issue.
As DEA in Benfield is the degradable component, accordingly any degradation may result in excessive foam as DEA may polymerize with the passage of time
In view of your situation I would recommend the following
Please
and avoid excessive foaming and however, please do consult UOP while doing so as I have seen a failure of Benfield absorber due to wrong location of sample collection resulting wrong determination of v+5 state as the side stream passsing carbon filter can regain the v5 state
Best regards
Good day!
I would recommend to at least share your PFD , current operating data so that our friends can access the actual issue.
As DEA in Benfield is the degradable component, accordingly any degradation may result in excessive foam as DEA may polymerize with the passage of time
In view of your situation I would recommend the following
Please
- Visually check color of the solution , if it is black and opaque it is clear indication of degradation of DEA
- Also analyze formation of Potassium formate
- Do check V+ and V+5 ions regularly. Often there is a rapid reduction of valence state of the corrosion inhibitor (vanadium) from the active V+5 to passive V+4 material is also observed
- Check over dosing of KNO2 used as oxidant
and avoid excessive foaming and however, please do consult UOP while doing so as I have seen a failure of Benfield absorber due to wrong location of sample collection resulting wrong determination of v+5 state as the side stream passsing carbon filter can regain the v5 state
Best regards
#8
- Members
- 87 posts
Gold Member
Posted 24 January 2013 - 04:16 PM
Hi Hazree,
This is very common and interesting in CO2 removal units. From your descriptions, I would like to list down following root causes for foaming and recommend some actions. The best decision will be to contact experts if you do not have in house resorces and skills.
Probable causes:
1. Condensation of HC ( like CH4) below 45 C which causes foaming.
2. Degradation of DEA into HSS ( Heat Stable Salts) which will foam, corrode and plug your equipments in the system; activated carbon bed can not remove these ionised particles.
3.Excessive dosing of antifoam ( normal rate should be 50-100 ml per shift).
4. Presence of oxygenated compound ( like Corrosion inhibitors) adding feed to DEA to degrade into HSS.
Recommendation:
1. Make a thorough analysis of your sample; contact MRP ( Netherlands),M.Coro/ M Tomasy from GV ,Italy for free analysis and troubleshooting .
2. Optimise CO2 scrubber inlet temperature to avoid HC condensation
3. Isolate filter when you are injecting antifoam ( I gues you blend thoroughly the antifoam with water before injecting). Inject antifoam based on foaming tendency ( foam test: Foam height and foam collapse time) and other operational symptoms like fluctuation of levels, temperature,DP etc.
4. Remove HSS by MPR or other company's suitable method or replace part of the solution with fresh make up.
5. Contact licensor or other experts who can help you.
Kind regards,
Satyajit
This is very common and interesting in CO2 removal units. From your descriptions, I would like to list down following root causes for foaming and recommend some actions. The best decision will be to contact experts if you do not have in house resorces and skills.
Probable causes:
1. Condensation of HC ( like CH4) below 45 C which causes foaming.
2. Degradation of DEA into HSS ( Heat Stable Salts) which will foam, corrode and plug your equipments in the system; activated carbon bed can not remove these ionised particles.
3.Excessive dosing of antifoam ( normal rate should be 50-100 ml per shift).
4. Presence of oxygenated compound ( like Corrosion inhibitors) adding feed to DEA to degrade into HSS.
Recommendation:
1. Make a thorough analysis of your sample; contact MRP ( Netherlands),M.Coro/ M Tomasy from GV ,Italy for free analysis and troubleshooting .
2. Optimise CO2 scrubber inlet temperature to avoid HC condensation
3. Isolate filter when you are injecting antifoam ( I gues you blend thoroughly the antifoam with water before injecting). Inject antifoam based on foaming tendency ( foam test: Foam height and foam collapse time) and other operational symptoms like fluctuation of levels, temperature,DP etc.
4. Remove HSS by MPR or other company's suitable method or replace part of the solution with fresh make up.
5. Contact licensor or other experts who can help you.
Kind regards,
Satyajit
#9
- Members
- 79 posts
Gold Member
Posted 25 January 2013 - 01:22 AM
Dear All
Good Day!
In my experience I have never heard of condensation of HC in Benfiled system. Also, to my knowledge there is not a single paper indicating such cause.Also, presence of HC , first of all indicated in the primary reformer, where presence of HC ( pentane and higher ) in natural gas results in carbon deposits in the tubes of primary reformer catalyst.Otherwise during normal operation with steam to carbon ratio of 3.0 , these HC are converted into hydrogen, Carbon dioxide and CO
Presence of HC and operation at low S/C some times results in methanol formation and some ammonia in secondary reformer and HTS/MTS. This results is some foaming without deterioration in color index and can be controlled by increasing steam at the inlet of HTS/MTS
Also, Absorber inlet temperature is normally in the range of 85 to 106 Deg C, which minimizes the chances of HC condensation / separation in absorber solution
Regarding activated carbon filter it adsorbs organic polymers formed as a result of degradation of DEA and is a standard feature of new Ammonia plants with Benfiled system for CO2 removal and UOPL (Licenser of Benfiled Process recommended side stream filtration for removal of degradation product)
We faced similar problem before we have activated carbon filter and after installation it is about 10-15 years of operation we are running with same solution with very small make up.
Partial replacement of solution will result in smooth operation for 4-6 months as experienced by us and the situation then becomes similar as before. Due to the presence of vanadium, it is very difficult to dispose / discard Benfiled solution and it have to be taken in Benfiled storage tank which is meant to store Benfiled solution in the event the absorbation need to be drained .
We Build new Benfiled tank to store the discared solution,
Another solution is to use Benfiled ACT-1 but this effects the Benfiled water balance and need detailed evaluation by UOPL
Good Day!
In my experience I have never heard of condensation of HC in Benfiled system. Also, to my knowledge there is not a single paper indicating such cause.Also, presence of HC , first of all indicated in the primary reformer, where presence of HC ( pentane and higher ) in natural gas results in carbon deposits in the tubes of primary reformer catalyst.Otherwise during normal operation with steam to carbon ratio of 3.0 , these HC are converted into hydrogen, Carbon dioxide and CO
Presence of HC and operation at low S/C some times results in methanol formation and some ammonia in secondary reformer and HTS/MTS. This results is some foaming without deterioration in color index and can be controlled by increasing steam at the inlet of HTS/MTS
Also, Absorber inlet temperature is normally in the range of 85 to 106 Deg C, which minimizes the chances of HC condensation / separation in absorber solution
Regarding activated carbon filter it adsorbs organic polymers formed as a result of degradation of DEA and is a standard feature of new Ammonia plants with Benfiled system for CO2 removal and UOPL (Licenser of Benfiled Process recommended side stream filtration for removal of degradation product)
We faced similar problem before we have activated carbon filter and after installation it is about 10-15 years of operation we are running with same solution with very small make up.
Partial replacement of solution will result in smooth operation for 4-6 months as experienced by us and the situation then becomes similar as before. Due to the presence of vanadium, it is very difficult to dispose / discard Benfiled solution and it have to be taken in Benfiled storage tank which is meant to store Benfiled solution in the event the absorbation need to be drained .
We Build new Benfiled tank to store the discared solution,
Another solution is to use Benfiled ACT-1 but this effects the Benfiled water balance and need detailed evaluation by UOPL
#10
- Members
- 4 posts
Brand New Member
Posted 10 August 2013 - 12:43 AM
Dear All,
Thanks for all the advise.
here is an update.
1) we are still seeing intermittent foaming in the system which we combat via antifoam injection.
2) The total organic compound (TOC) analysis shows a figure in the 30,000 ppm which I think an indicative of heavy hydrocarbon presence in the system. So I think cannot eliminate this cause for foaming.
3) Our total suspended solid reading is kept below 10 ppm which shows our mechanical filter is effective to remove this potential culprit.
4)the formate analysis shows around 700 ppm of reading.
There is also suggestion to keep delta T between inlet feed gas into absorber and potassium carbonate circulation into absorber between 5 to 8 degrees to avoid HC condensation. How credible is this advise?
No comments:
Post a Comment