Hydrate formation, corrosion, erosion, pipeline blockages — all of these trace back to inadequate dehydration.
Pipeline specification typically requires ≤ 6–7 lb/MMSCFD water content in sales gas.
A technical study titled “Natural Gas Dehydration with Triethylene Glycol (TEG)” (European Scientific Journal, 2015) https://lnkd.in/gqE2te9n used Aspen HYSYS to simulate a 10 MMSCFD gas stream at 6200 kPa and 30°C to evaluate TEG circulation rate versus dehydration performance.
Here’s what stood out:
🔹 Feed gas water content: ~17 lb/MMSCFD (well above spec)
🔹 TEG rates evaluated: 50–70 L/h
🔹 At 53 L/h → 6.455 lb/MMSCFD (within pipeline spec)
🔹 At 70 L/h → 1.579 lb/MMSCFD
Yes — increasing TEG reduces water content. But beyond ~53–70 L/h, the incremental benefit becomes economically questionable.
The key insight: More TEG does not necessarily mean better plant economics.
Running above 70 L/h:
-> Adds circulation load
-> Increases regeneration duty
-> Raises pumping and heating costs
-> Risks absorber flooding and carryover
Meanwhile, hydrate formation temperature dropped significantly as TEG increased (from +18°C before dehydration to as low as -38°C at 70 L/h), demonstrating how dehydration shifts operability margins.
For engineers designing or troubleshooting TEG units, this reinforces a critical principle:
OPTIMISE for the minimum circulation rate that meets spec — not the lowest possible water content.
Designing dehydration units is always a balance between:
• Capital cost
• Operating cost
• Glycol losses
• Hydrate safety margin
• Process reliability