Corrosion Simulation Experiment Research Of Typical Materials Resistant Naphthenic Acid

Naphthenic acid corrosion is a kind of corrosion from which often occurs at the location of high temperature equipments and line in the first processing petroleum oil units. It often lead to serious corrosion hazard. It is one of the difficult problems in refining high acid crude oil which needs to be settled .In this paper, a dynamic naphthenic acid corrosion simulation test equipment was used for simulating a medium of high temperature naphthenic acid corrosion of materials which was often used for refining equipment. It revealed corrosion rate change regularity of typical refinery and petrochemical plant materials (carbon steel, Cr5Mo, 304L, 316L) at different temperatures, different acid number and different flow rate of the media. It has obtained corrosion rate data of typical material in the dynamic conditions of high temperature naphthenic acid, and briefly put forward measures to prevene and cure naphthenic acid corrosion.Subject of this study is basic research projects. It mainly takes into account the naphthenic acid corrosion impact of temperature, naphthenic acid, medium flow rate, materials and other factors .In accordance the purpose of the study ,It designed testing program. Using of a dynamic naphthenic acid corrosion simulation test equipment which was designed only by Sinopec Qingdao Safety Engineering Institute, selecting the carbon steel, Cr5Mo, 304L, 316Letc of typical materials of refining plant as study subject, it conducted naphthenic acid corrosion test of materials at the design temperature, naphthenic acid value and flow rate of medium, and acquired the dynamic naphthenic acid corrosion rate data. using of scanning electron microscopy ,it also analysis microstructure corrosion morphology of the materials. The refined naphthenic acid which was used in this topic was also conducted TBP distillation. Distillate segments acid numbers were determined by automatic potentiometric titrimeter.Experimental studies have shown that when acid value and medium flow rate was constant, with the increasing of medium temperature, high temperature naphthenic acid corrosion rate was increasing, and the temperature exceeded 230℃, the four materials was beginning to increase obviously.When medium temperature and flow fate was constant, with the increasing of naphthenic acid value, high temperature naphthenic acid dynamic corrosion rate was also increased, and acid valve 10.0mgKOH / g was as a the critical value at which corrosion rate increased obviously. When temperature and naphthenic acid valve was constant, with the increasing of naphthenic acid media flow rate, high temperature naphthenic acid dynamic corrosion rate was also increased ,and 25m / s of medium flow rate may be used as the critical flow rate value of the test conditions. Refined Naphthenic true boiling point distillation test showed that naphthenic distillate was mainly concentrate at temperature segment of 350-390℃. As the temperature increases, the cut fraction segment acid number decreased.Naphthenic acid corrosion trust results of four materials showed that the resistance naphthenic acid corrosion performance of four materials from poor to good was carbon steel, Cr5Mo, 304L, 316L. Chromium and molybdenum element of alloy steel contained is important for resistant naphthenic acid corrosion of alloy steel. Finally, protection measures of naphthenic acid corrosion is the primary means of controlling naphthenic acid corrosion.