Rich Amine Corrosion

Material

Carbon and low alloy steels

Amine Concentration (wt%)

Determine the amine concentration in the Equipment/ piping. Due to vaporization of water, a local increase in amine concentration may need to be considered in evaluating the corrosion of some reboilers and reclaimers.

Yes

Acid Gas Loading (mole acid gas/mole active amine)

Determine the acid gas loading in the amine. If analytical results are not available, it should be estimated by a knowledgeable process engineer.

Yes

Velocity (m/s; ft/s)

Determine the maximum velocity of the amine in this Equipment/piping.

Note: If required for monitoring purposed, requires recalculation into (mass) flow.

Heat Stable Amine Salt (HSAS)

In MEA and DEA, "HSAS" represents the normal family of amine degradation products.
In MDEA "HSAS" refers to organic acid contaminants, mainly formate, oxalate, and acetate.

Note: Concentration:

MEA and DEA (£ 2, 2-4 or > 4wt.%); MDEA (< 500, 500-4000 or > 4000 ppmw)

Yes

Maximum Process Temperature (°C; °F)

Determine the maximum process temperature. In reboilers and reclaimers, tube metal temperatures may be higher than the bulk process temperature.

Note: Absorber column typically below 88°C (190°F).

Yes

Absorber bottom

Maximum acid gas loading

mol_acid/mol_amine

Typically, once a day

Standard / Monitoring (Max.)

Absorber bottom temperature calculated from the temperature measured just before the let-down valve.

Temperature

°C

Continuously

Standard (Max.)

Rich solvent

Flow rate

m/s

TBD / Site specific (e.g., depends on stability of the operation)

Monitoring (Max.)

Rich solvent

Flow rate

m/s

TBD / site specific

Monitoring (Min)

Rich amine: Lean-rich exchanger tubes and piping downstream Lean-rich exchanger

Temperature

°C

TBD / Site specific; preferably continuous

Standard / Monitoring (Max.)

Lean amine

Solvent strength

wt.%

Typically, once a day (depends on frequency of fluctuations of the solvent strength)

Standard / Monitoring (Max.)

Lean amine

Chloride content

ppmw

TBD / Site specific

Monitoring (Max.)

Lean Amine

pH

-

TBD / Site specific / typically 3 times a week (but much more frequent than the "fingerprint" or "Huntsman" analyses).

Standard / Monitoring (Min.)

Lean Amine

Maximal content of heat stable amine salts (HSAS).

wt.% on total solvent

Site specific but recommended at least once per quarter and additional when the pH IOW is on or nearing the limit.

Monitoring (Max.)

Lean Amine

Maximal Total Suspended Solids (TSS)

ppmw

TBD / Site specific

Monitoring (Max.)

Degradation mechanism can be properly controlled.

• "Yes": When all the IOWs in the table above are properly controlled and corrosion rate managed below 0.2 mm/y (8 mils/y).
• "Intermediate": When operating conditions indicate a theoretical corrosion rate above 0.2 mm/y (8 mils/y); i.e., StF Medium.
• "No": When one or more IOW limits are frequently exceeded or theoretical corrosion rate above 0.6 mm/y (24 mils/y); i.e., StF High.

Relevant process parameters are reliably monitored.

• "Yes": All relevant process variables known and actively monitored, including development of amine strength, heat stable amine salts and total solid content.
• "Intermediate": Relevant process variables known but not actively monitored and/or exceedances not always acted on.
• "No": No IOW available or no follow up on exceedances.

Reliable inspections were carried out.

• "Yes": 3 inspections above ‘usually effective’.
• "Intermediate": 1 – 2 inspections above ‘usually effective’.
• "No": No inspections or ineffective inspections.