Gas Processing & Treating (Midstream)

Dehydration is the process of removing water vapor from the gas stream. Several methods can accomplish it, but the process FET uses is called glycol absorption. This process employs a hygroscopic liquid (glycol) to remove the water vapor from the gas in the tower.

Diethylene (DEG) and Triethylene (TEG) glycols are the two liquids generally used for gas dehydration. TEG is a liquid desiccant that attracts and retains water at low temperatures but releases the water at high temperatures in the regen reboiler. Using TEG has the following advantages:

• TEG readily regenerates to a 98-99.5% solution in an atmospheric stripper due to its high boiling point and other physical properties, allowing for substantial dew point depressions in the range of 80°-140°F.
• TEG has an initial theoretical decomposition temperature of 404°F, while the degradation temperature of diethylene glycol is only 328°F.
• The evaporation losses are lower for TEG than DEG.
• Simpler regeneration equipment is required.
• Dehydration operating and capital costs are lower than with DEG.

A Gas Dehydration Unit comprises a contactor/absorber (tower) and a regenerator/reconcentrator (regen). FET offers two kinds of towers: the Bubble Cap Tray (BCT) and Packed Tower. When you provide your design conditions and project strategy, our engineers will help you determine which tower design you need to optimize your project.

FET can manufacture gas dehydration towers for flowrates from 10MM (16” OD) to 250MM (72”ID) and five standard regens from 500K to 2.0MM BTU/HR. For more complex applications, we offer custom regens up to 6.0MM BTU/HR with a various options to meet our customers’ requirements.