EFFECT OF NAPHTHENIC ACIDS CONTENT IN PETROLEUM ON THE CORROSION PROCESSES DURING PROCESSING

The processing of petroleum with high content of naphthenic acids is usually accompanied by intense deterioration of the equipment in the temperature range 200-400 degrees C. At these temperatures characteristic for the intermediate fractions obtained from atmospheric and vacuum installations, low-molecular weight naphthenic acids are released which are known for their high activity towards metals. The increased acidity of petroleum could be due to other oxygen containing compounds which could be partially destructed during distillation to lower-molecular weight fatty acids. The contents of sulphur compounds in petroleum can result either in increased or decreased corrosion rate. Under certain conditions (sulphur concentration in petroleum, medium pH), protective layer of ferrous sulphide is formed oil metal surface which isolates it from the aggressive medium. The naphthenates formed in the interaction between naphthenic acids and iron do not possess such protective properties and, unlike ferrous sulphide, Would rather facilitate metal destruction.