By David Hoskins, Updated Mar 24, 2022
Natural gas supplies roughly 24% of the United States’ energy needs. Before it reaches consumers, the gas is refined to a high‑purity methane stream. A key step in this refinement is the removal of moisture, which can otherwise reduce pipeline capacity, cause corrosion, and create safety hazards. The dehydration process closely mirrors that used for refining crude oil, and relies on three main technologies: Joule‑Thomson expansion, solid desiccant dehydration, and liquid desiccant dehydration.
Natural gas enters a heat exchanger, where it is cooled to lower its temperature.
The cooled gas is then passed into a low‑temperature separator. Rapid cooling causes water vapor to crystallize as ice, which falls out of the gas stream.
The dehydrated gas exits the separator and may proceed to additional treatment stages if required.
The gas enters the bottom of a desiccant tower.
It flows upward through adsorbent media—such as silica gel, molecular sieves, activated alumina, or activated carbon—until the tower’s moisture capacity is reached.
While the first tower regenerates, the gas is routed to a second tower, using an indirectly heated portion of the processed gas.
The regenerating gas passes through an air‑cooled heat exchanger, where the adsorbed water crystallizes and is removed.
The regenerated gas is recycled back to the first tower, and the cycle continues until the moisture level falls within the acceptable range of 4–7 lb per million standard cubic feet.
The gas enters a contactor tower.
Tri‑ethylene glycol (TEG) solution is pumped into the tower’s top, flowing downward across bubble trays to contact the gas.
As the gas traverses the trays, the TEG absorbs water vapor, producing a dehydrated gas stream that exits at the tower’s top.
The TEG, now enriched with water, is collected at the tower’s bottom and heated to drive off the moisture. The regenerated TEG is then returned to the top of the tower to repeat the cycle.
Only trained professionals should handle natural gas processing, and it must occur in facilities compliant with regulatory standards. Natural gas is highly flammable; strict safety protocols are essential.
