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 Non-corrosive 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 |