Processing natural gas for pipeline delivery requires removal of water vapor from the inlet gas stream to meet pipeline specifications and to prevent corrosion and the formation of hydrates, a crystallized gas/water compound. Water vapor removal is accomplished by dehydration, which usually involves one of two processes: absorption or adsorption.

Dehydration methods. Absorption occurs when the water vapor is removed by a liquid dehydrating agent. Adsorption occurs when the water vapor is collected on the surface of the solid desiccant.

The most common method of absorption dehydration uses glycol (TEG), a liquid dessicant dehydrator, to absorb water vapor from the gas stream in a trayed contactor tower. As the glycol solution is brought in contact with the wet gas stream, the solution absorbs the water and exits the bottom of the contactor, while the dry gas exits the top of the vessel.

By contrast, adsorption uses a solid dessicant dehydrator, generally silica gel, activated alumina, calcium chloride, or molecular sieve. Two or more adsorption towers are filled with the solid dessicant; as the wet gas passes through the tower from top to bottom, water is retained on the surface of the desiccant, leaving dry gas to exit the bottom of the tower.

Effective dehydrator performance. CB&I has extensive experience in the design and construction of both types of gas dehydration systems. CB&I has designed and built liquid desiccant dehydrators with capacities ranging from 2 gallons per minute (GPM) up to 150 GPM, and solid dessicant dehydrators with capacities up to 1 billion cubic feet per day.

We can design and construct gas processing plants anywhere around the world, even in the most logistically challenging circumstances. Our global engineering, procurement, fabrication and construction resources can be mobilized to virtually any location and, depending on the project requirements, we can build plants utilizing either modular or conventional construction methods, or a combination of both.