Natural gas often comes out of the ground mixed with water vapor. This "wet gas" can be separated using two primary methods:
Glycol dehydration – Wet gas moves through an inlet pipe into a tank called a "contactor." A rounded cap over the inlet pipe forces the gas to flow down into a pool of glycol solution at the bottom of the tank. Glycol has a strong affinity for water, so the water molecules from the wet gas bond to the glycol molecules in the solution. The vapor-free natural gas is collected from the top of the contactor.
Because water boils at 212F and glycol doesn't boil until 400F, simple heating is all that is required to vaporize the captured water so the glycol solution can be reused.
Solid-desiccant dehydration - This method is typically more effective than glycol dehydration, but requires higher volumes of natural gas moving under high pressure. The wet gas is pumped downward through a tower filled with a solid desiccant (drying agent). The desiccant attracts and binds the water molecules so that only dry gas flows out the bottom of the tower.
When the desiccant has captured all the water it can, operators flush the tower with heated gas that re-vaporizes the water molecules, thereby "reactivating" the desiccant.»next