The amine treatment process is one of several “sweetening” processes that allows the removal of excess carbon dioxide (CO2) and hydrogen sulfide (H2S) from acidic or sour gas and natural gas liquid (NGL). When collected, natural gas contains varying amounts of these substances. Aside from hydrogen sulfide being a risk to human health, it and carbon dioxide — when bonded with water — form sulfuric and carbonic acid respectively. These acids create corrosion problems in pipelines and other distribution systems.
In some cases CO2 and H2S can be vented or flared to the atmosphere; however, environmental regulations around the world restrict how much H2S can be flared, requiring a treatment process using special catalysts and solvents to safely remove it and CO2 . Amine treatment units have various components, but the main idea behind them is to use a calculated concentration of an aqueous solution of alkylamines or “amines” to absorb the gases from the sour gas in an absorber. The “sweet” gas is then lifted out while the amine solution rich in acid gases then passes through a flash drum and a regeneration unit that separates the acid gases out of the amine solution. The acid gases typically are ushered off to a sulfur recovery unit while the scrubbed amine solution is reused.
Modern amine treatment units are typically able to be customized to handle various circulation rates and different types of amines, from diethanolamine (DEA) to diglycolamine (DGA). Additionally, the components most susceptible to corrosion are crafted from low-carbon stainless steel like 316L. The design process takes into account the benefits of modular design, with many units ultimately getting built into compact skid designs for rapid installation and maintenance. These design choices not only make initial installations easier; they also provide significant flexibility for facilities to efficiently make brownfield modifications to their systems as technology advances and equipment wears down.