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There are 6 identical trains processing natural gas bringing H2S < 4PPM and CO2 From 5% to 2%. All parameters are same. MDEA is the solvent used. But interestingly out of the 6 absorbers one is not properly functioning in terms of capacity and quality.The lean amine in all other absorbers is pale yellow and the one having problems is brownish. The solvent tested for all parameters, found ok except colour. Could any one come out with a solution?
 
Answers
27/05/2018 A: Pronab Mistry, ADNOC Gas Processing, pronab88@yahoo.com
Normally there should be a amine filtration system. Confirm firm filtration is running smooth and also carbon filter is working fine. You should check RSH in lean amine sample it should be less than 100 ppm.
14/03/2017 A: NS Murthy, Suez, murthy.ns.ext@suez.com
Brownish indicate potential corrosion / fouling issues. It is not clear whether the amine regenerator is common to all these absorbers or each absorber has its own regenerator too.
Check for the following: -
1. Acid gas loading (i.e. mole of H2S+mole of CO2 per mole of MDEA) in rich amine.
2. Velocity of rich amine
3. Foaming tendency of lean amine
4. Condition of mechanical and carbon filters on lean amine
5. pH of lean amine which gives roughly the level of degraded amine that is to be purged from the system.
Additionally contact your GE representative nearby to further assist on all the above and set appropriate safe operating window within prescribed limits.
Good luck.
13/03/2017 A: Egbert van Hoorn, Hocon B V, Egbertvh@hotmail.com
It is very likely that brownish colour of the problematic sample is due to corrosion. This is likely the rich amine and not the lean amine. The reason could be a too low amine circulation rate but other things affect corrosion as well.
Detailed simulations of your amine system can help to clarify the current problem.
A brown/grey colour is typically caused by FeS particulates.