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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

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