Q & A > Question Details
We have some LPG Merox units with amine absorber before the Merox unit. We use MDEA in the amine absorber and we have experienced some problems of amine carryover in the LPG.
Can anyone comment on the impact of the amine contamination in the Merox units? Besides the possible formation of emulsions, could there be any other problem?
06/01/2017 A: Muhammad Faisal, Oman Oil Refineries & Petroleum Industry (Orpic)-Oman, engr.faisalfraz@gmail.com
Carry over of amines with LPG has followings impacts on downstream merox operation (LPG Merox):
1. Check water coalescer operation, chance of foaming in coalescer is higher.
2. check amines concentration in circulating H2O (2~3 wt% allowable).
3. all amines shallbe trap in water coalescer. howevr, few traces shall be treated in Caustic prewash section where less concentration (10Be Caustic) comparing to extractor caustic (20Be), is used to remove any traces of sulfidic amines if carryover from coalescer.
4, check Lead acetate test for sulfides/H2S presence in both LPG outlet from Prewash (UOP-212 test), while lead acetate for prewash caustic. replace caustic, if quality (spent, alkalinity, % amines are higher).
Note: all H2S shall be treated in Pretreatment section, if any H2S breakthrough pretreatment section, then it is fewer chances that it can be removed from post treatment i.e. extraction, sand filter, CoS treatment.
22/02/2016 A: Eric Hennings, Technip Stone & Webster, EHennings@technip.com
Emulsions will be a serious problem. Also, rich amine contains H2S which becomes Na2S. Regeneration of caustic becomes problematic at Na2S >2%
29/11/2015 A: Sridhar Balakrishnan, Bharat Oman Refineries Limited , laksrid@yahoo.com
Carryover of amine with hydrocarbons can cause foaming, possible corrosion in systems.
24/11/2015 A: Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
Amine carry over with LPG will lead to Amine levels lost and H2S slippage into Caustic prewash. H2S slippage will lead to premature exhaustion of Caustic prewash and frequent replenishment of Prewash Caustic.
24/11/2015 A: Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
Amine carry over from amine absorber into Merox can be detrimental for several reasons:
1) Formation of stable emulsions may cause upsets in Merox unit will likely lead to caustic carryover which may put LPG product off spec
2) You may experience very high salt consumption downstream in salt drier.
3) You may also experience high corrosion rates in Merox unit.
4) Gradual build up of salts in Merox solution will eventually mean the Merox solution will need to be purged and replaced.
High efficiency PhaseSep Liquid Liquid coalescers have been commercially proven to remove carried over amine from LPG to very low levels. However we would first recommend an audit on the amine system . Depending on the root cause of the amine carryover, there could be different solutions offered.
24/11/2015 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
There should be no problem in the Merox section if the carryover is minor. Caustic and amine are sometimes used as a mixture in treating LPG for COS removal.