Processing and distributing natural gas in a safe and efficient manner isn’t as simple as taking it from the ground and piping it out for sale. It must be processed to remove acid gases and other liquids, including natural gas liquids (NGL). These liquids — often referred to as condensates — can further yield useful products like butane, ethane, and propane. However, this condensate must be processed as many of the hydrocarbons are lighter (increasing vapor pressure) and more dangerous to handle. Many producers choose to stabilize the condensate first by removing lighter hydrocarbons like methane.
Condensate stabilization units are the primary method for making condensate from natural gas streams easier to manage. These units can vary in design and purpose, from a one-tower set-up to multiple towers, depending on how much the condensates need to be processed. Generally speaking, upon entering a standard stabilization unit, the condensate stream is heated and fed into the top of a tower at a specific pressure. The methane vaporizes out the top of the tower and passes through a cooler, separator, and compressor. The methane feed is then merged with an existing sweet gas stream or used as fuel at the facility for furnaces or steam boilers. The heavier hydrocarbons, now more stabilized, collect at the bottom of the tower and are removed for distribution to atmospheric storage tanks before being shipped out. In more advanced scenarios, the remaining condensate can be run through additional towers on site to further fractionate the hydrocarbons.
Stabilizer units take on many shapes and sizes and appear in many facilities, from well pads to central gathering facilities. Like amine treatment units, stabilizer units are increasingly designed with modularity in mind, allowing for quick installation and swap-out. Designs can be modified to handle as little as 2,000 barrels per day or as much as 20,000 or more barrels per day. Monitoring systems for the unit may be pneumatic, instrument gas, or fully electronic depending on customer needs.