Engineering Evaluation Case: A TEG Regenerator Fouls Even Though the Gas Contactor Packing Is Clean
A TEG dehydration system contains more than the gas contactor.
The rich glycol must also be regenerated.
Contaminants carried through the glycol loop can accumulate in the hot regeneration section even when the absorber packing itself remains relatively clean.
Project Situation
Consider a natural-gas dehydration unit.
The contactor performs reasonably well.
Over time, the glycol regenerator develops:
- higher pressure drop;
- poor stripping;
- deposits in the hot section;
- darkened glycol.
The plant initially focuses on the contactor because dehydration performance is falling.
The root problem may be the regeneration loop.
Rich Glycol Carries Contaminants
TEG can transport:
- salts;
- corrosion products;
- compressor oil;
- heavy hydrocarbons;
- degradation products
into the regenerator.
Heating then changes their behavior.
High-Boiling Material Accumulates
Components that do not leave with the regeneration vapor remain in the glycol.
As concentration increases, they can form:
- deposits;
- sludge;
- coke-like material under severe conditions.
Hot Packing Is a Deposition Surface
The regenerator packing provides:
- large area;
- repeated wetting.
Contaminated glycol can leave residues on that surface.
The bed gradually loses:
- effective area;
- open flow.
Higher Heat Does Not Always Restore Performance
Increasing reboiler temperature to achieve lower water content can worsen thermal degradation if the glycol is already contaminated.
Filtration and Glycol Quality Matter
Maintaining clean glycol can protect both:
- contactor;
- regenerator.
The regeneration tower should therefore be evaluated as part of the whole solvent loop.
Engineering Takeaway
Clean contactor packing does not prove that the regeneration side of a glycol system is clean.