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Table 6 The amine analyses results, allowable limit, source, and effects of contaminant

From: Ethylene glycol elimination in amine loop for more efficient gas conditioning

Component SPEC Train #2 Train #1 Train #3 Train #4 Source Notes
H2O (wt%)   34.6 48.4 39.4 41.3   
Total amine content (wt%)   43.5 43.1 45.9 43.5   
MDEA (wt%) 50 43.4 32.8 33.3 32.9   
MEA (wt%)    0.1 0.1 0.1 Degradation in the presence of oxygen Can be turned to N-(2-hydroxyethyl) ethylenediamine (HEED)
It is non-corrosive
It promotes thermal degradation of MDEA in presence of oxygen
DEA (wt%) 5000 ppm   0.1 0.1 0.1 In the presence of oxygen at a temperature above 82° C DEA is formed carbamic acid with CO2, this acid can be turned to the n,n,n-tris-(2-hydroxyethyl) ethylenediamine (THEED). THEED corrosion rate is 6 times higher than DEA
MEG (wt%)   19.8 8.3 15 14   
Iron (ppmv) 20 mg/l < 1 1 3 1 Production of corrosion or erosion  
Nickel (ppmv)   2.8 1 1 1 Production of stainless steel corrosion Must be monitored and checked by corrosion coupon
Chromium (ppmv)   < 1 1 1 1 Production of stainless steel corrosion Must be monitored and checked by corrosion coupon
CO2 (mol CO2/mol MDEA) 0.005 < 1     CO2 in regenerated amine Helped to the corrosion with formation of HSAS
H2S (ppmv)   < 1      
Acetate (ppmv) 1000 3584 1250 3350 2200 Combination of amine, glycol with oxygen  
Formate (ppmv) 500 108 90 140 120 Reaction of amine with oxygen at temperature above 121 °C For 2000 ppm formate, severe corrosion occurs especially in the top of the regenerator
Chloride (ppmv) 200 52 300 40 20 In make-up water and in feed gas With amine formed amine chloride
Increases the pitting corrosion
Leads to the corrosion and erosion of stainless steel and total corrosion of carbon steel
Sulfate (ppmv) 500 80 30 130 75 Oxygen of make-up water is reacted with H2S Increases the rate of corrosion
Can be formed Bicine
Oxalate (ppmv) 250 < 1 15 25 25 Reaction of amine with oxygen at temperature above 81 °C Chelating agent
Increases the corrosion
Thiosulfate (ppmv) 10,000 < 1 15 40 10 Entering oxygen to the system Purging the water of reflux drum can reduce it
Thiocyanate (ppmv) 10,000 < 1 10 10 10 In the feed gas
H2S + O2 + HCN
Non corrosive
Nitrate (ppmv)   < 1      
Phosphate (ppmv)   < 1      
Glycolate (ppmv) 500 270 300 430 250 Reaction with oxygen in temperature above 82 °C Causes the corrosion
Butyrate (ppmv)   < 1 10 10 10   
Sodium (ppmv) 200 < 1 20 20 20 Water make up  
Potassium (ppmv)   < 1 10 20 10 Water make up  
Ammonium (ppmv) 10,000 < 1     Amine thermal and oxygen degradation. Side production of cyanide with water If ammonium is condensed, it absorbed CO2, formed carbonate ammonium or bio carbonate and block the condenser path
It can absorb H2S and formed biosulphide that it is corrosive
Magnesium (ppmv)   < 1 1 1 1   
Calcium (ppmv)   < 1      
pH > 10 10.3 9.9 9.7 9.8   
Total solid content (wt%) 10 ppm 0.013 3.7 6.7 6.7 Weak in primary separation, corrosion from the filters TSS must be less than 100 ppm
Average particle size (µm)   6.5      The average particle size shall be less than 5 μm to prevent foaming
Silicon (ppmw) 25   25 25 30 Antifoam It absorbed in the carbon filter and covers the cartridge filter
Amino acid (ppm)    10 10 10   
Bicinne 250      MDEA covert to TEA. TEA reacts with oxygen to form bicine
Cyanide + formaldehyde
Severe corrosion especially in reboiler
Chelating agent
If bicine is more than 250 ppm, corrosion more than 10 mpy is expected for carbon steel
Can be removed by vacuum distillation and ion exchange
Manganese 0.5 PPMV      Carbon steel corroded  
MMEA       In the presence of oxidant and acids, MDEA converts to MMEA at high temperature Can be converted to the DMHEED
Can be made situation with potential for corrosion
Can be removed by vacuum distillation
Acid acetic       Temperature more than 121 °C and presence of oxygen Water washing before absorber can be reduced it
Oxygen       Fitting and metering in wellhead equipment, lines are corroded or amine tank if has not nitrogen as inert gas In presence of oxygen, MDEA, after a while, converts to the DEA
For less amount of oxygen, oxygen scavenger such as hydrazine, amine hydroxyl can be used
Nitrogen blanketing in amine tank
Oxygen solubility in amine is 2 to 10 ppmv
100 ppmv of oxygen in feed gas can produce high amount of HSS
HSS 0.5 to 1.0 wt%      When amine react with acids stronger than H2S and CO2 Increases foaming, viscosity and mass transfer, decreases capacity of acid gas absorption
CO2/H2S       For ratio less than 19, total acid gas in amine increases relatively because of protection layer of FeS  
Color       Dark coffee from corrosion
Dark brown from thermal destroyed
When the amine is brown, after passing of filter paper, the color is changed, the source is corrosion otherwise the source is amine thermal degradation
Foam tendency Nil to 30 s      Hydrocarbon and solid particle