51316-7491-Evaluation of Various Phosphate Esters on High Temperature Corrosion control and Fouling Potential in Refining Systems

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Product Number: 51316-7491-SG

ISBN: 7491 2016 CP

Author: James Ondyak

Publication Date: 2016

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The use of phosphorus based inhibitors is a common strategy to control Naphthenic acid corrosion. Some users have experienced phosphate fouling that has been attributed to use of these inhibitors. As a result some have limited the amount of allowable phosphorus potentially reducing flexibility to safely use high TAN (Total Acid Number) opportunity crudes.Studies were performed on various commercially available phosphate esters to determine their relative phosphorus efficiency. Tests were conducted in a variety of corrosion conditions – naphthenic acid corrosion sulfidic corrosion and a combination of naphthenic and sulfidic at levels of temperatures TAN and shear stress of concern to refiners. These tests show dramatic differences in phosphorus efficiency. Depending on conditions some esters take as much as eight to ten times more phosphorus than others to obtain equivalent corrosion control. Differences in phosphorus efficiency were found to be correlated with the thermal stability oil solubility and acidity (degree of esterification) of the phosphate ester. Compounds that are more stable more soluble and less acidic are shown to be far more phosphorus efficient than compounds that are relatively less thermally stable and more acidic. The tests used to determine phosphate ester inhibitors thermal stability oil solubility and inhibition efficiency will be discussed. These lab methods can be used to pre-screen inhibitors reducing the number of field tests and associated costs fordeveloping an inhibitor application.