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Natural Gas Amine Sweetening (pH & Oxygen)

Natural Gas Amine Sweetening

After extraction, raw natural gas must go through processing before it is suitable for industrial, commercial, and residential usage. Often the fi rst stage of gas processing is known as "sweetening" where hydrogen sulfi de (H2S) and carbon dioxide (CO2) are removed through exposure to chemicals known as amines.

Oxygen Measurement Challenges
Oxidation is the enemy of amines. The presence of oxygen will cause the amines to degrade into heat stable amine salts (HSAS) such as acetate, oxalate, glycolate, bicine, and formate. The formation of these salts creates multiple problems. The acid removal capabilities of the amine solution is now decreased due to the conversion to salts. Chemical usage must increase to reduce the risk of contaminants passing through to the dehydrator. The second problem is the corrosive nature of the newly formed heat stable salts.

pH Measurement Challenges
Gas purification is continuous process; however most facilities rely on once-a-day laboratory pH readings to adjust the stripping column controls. We believe this trend of lab pH checks is simply due to the historical difficulty of making a reliable on-line pH measurement on the rich and lean amine streams.