The purpose of a glycol dehydration unit is to remove water from natural gas and natural gas liquids. When produced from a reservoir, natural gas usually contains a large amount of water and is typically completely saturated or at the water dew point. This water can cause several problems for downstream processes and equipment. At low temperatures the water can either freeze in piping or, as is more commonly the case, form hydrates with CO2 and hydrocarbons (mainly methane hydrates). Depending on composition, these hydrates can form at relatively high temperatures plugging equipment and piping. Glycol dehydration units depress the hydrate formation point of the gas through water removal. Without dehydration, a free water phase (liquid water) could also drop out of the natural gas as it is either cooled or the pressure is lowered through equipment and piping. This free water phase will often contain some portions of acid gas (such as H2S and CO2) and can cause corrosion. For the above two reasons the Gas Processors Association sets out a pipeline quality specification for gas that the water content should not exceed 7 pounds per million standard cubic feet. Glycol dehydration units must typically meet this specification at a minimum, although further removal may be required if additional hydrate formation temperature depression is required, such as upstream of a cryogenic process or gas plant.

TEG - with no additives - is often used to remove the water from natural gas. However, the extreme temperatures this process requires result in the formation of organic acids, such as glycolic, formic and acetic acids, in a process known as glycol degradation. This process forces the system’s pH down to an unstable level, causing the pure TEG to become corrosive and leaving the system unprotected.

Straight TEG is simply the raw glycol preferred to dehydrate natural gas. Triethylene glycol is a member of a homologous series of dihydroxy alcohols. It is a colorless, odorless and stable liquid with high viscosity and a high boiling point. Apart from its use as a raw material in the manufacture and synthesis of other products, TEG is known for its hygroscopic quality and its ability to dehumidify fluids. The inhibitor additive package utilized in this fluid is designed to control and limit the formation of thermal and oxidative degradation by-products as well as neutralized detrimental corrosive acids extending the fluids operating life and system operating temperatures. The inhibitors also protect metals against the corrosive tendencies of hydrogen sulfide (H2S), carbon dioxide (CO2) and other acid gasses with no negative effects on the water absorbing properties of the fluid.

By utilizing the KOSTCare™ Fluid Analysis Program. Please visit link for more information.

KOST USA uses only high quality virgin raw materials in our products. A product made from recycled glycol will almost always be lower in price but at what cost. The recycled glycol has already been used once and no matter how well the reclamation process works the fluid may contain impurities that will likely cause system contamination as well as reduced fluid life.

Buffering the systems pH and reducing the degradation of the glycol are the two keys to a quality inhibited TEG product. Effectively controlling these two aspects will assists in protecting the entire dehydration unit against corrosion and extend the life of the fluid. Reserve Alkalinity quantifies the amount of buffer in the formulation. This is an indication of the fluids ability to handle acid or other corrosive contamination. Some of these contaminants may be chloride, sulfate and carbonates that are often carried in from the gas to be dried. Carbon dioxide and hydrogen sulfide often found in gas streams can be corrosive when absorbed into the Triethylene glycol system. Carbon dioxide will often react to form carbonic acid which is corrosive. Additionally, as the glycol is continually exposed to high temperature as a result of repeated regeneration the glycol continues to degrade. As it degrades the formation of acetic, formic and glycolic acid. These acids will make the pH drop if the fluid is not properly buffered with inhibitors.