| Medium was harmful to corrosion carbon steel in Industrial production. Especially in the dynamic medium, erosion-corrosion is more serious, which increasingly raised people’s concern. The rotary hanging plate method, spraying method and piping method are used to study how dynamic corrosion medium effect on corrosion behavior of carbon steel. The pipeline method, as a method closer to actual industrial production, was studied in this paper. The main factors, such as composition of corrosion medium and flow velocity of medium, was studied in this paper. At the same time, effect of corrosion prevention about water-soluble imidazoline amide corrosion inhibitor in a case of scouring also was studied.According to range of flow velocity, experimental device was designed. To study on how the velocity (Om/s,1m/s,4m/s,8 m/s,12m/s, 15m/s) effect on carbon steel corrosion rule, experiment conditions was designed as follows:time was 2h, simulate corrosive medium was HCl solution (250mg/L,500mg/L,750mg/L) and acetic acid solution (250mg/L,500mg/L,750mg/L). The weight gain and loss method was used to study how velocity effect on the corrosion rate of carbon steel; scanning electron microscope (SEM) was used to study corrosion morphology of carbon steel; and the energy dispersive spectroscopy (EDS) was used to analyze ingredients of corrosion product on surface of carbon steel. Relationship of flow velocity of fluid and factors of hydrodynamics, effect of velocity on rate of corrosion and relationship of corrosion and factors of hydrodynamics were investigated in this paperThe results show that:the highest velocity, reach up to 16.8m/s, can fully meet the demand in test. In static state, rate of corrosion of Q235 carbon steel is 0.034mm/a in corrosion medium of hydrochloric acid and acetic acid, which belong to medium-low degree of corrosion. When the velocity exceeds lm/s, the corrosion rate of carbon steel reach up to 0.39mm/a, which belong to serious corrosion. In the ultra-high velocity (lOm/s), the corrosion rate of carbon steel is 1.0mm/a, which is so serious that influence greatly corrosion velocity of carbon steel. Scanning electron microscopy was used to observe carbon steel corrosion morphology, the carbon steel corrosion morphology is grooved at velocity of 1-8m/s, while the corrosion morphology is uniform at the velocity beyond 8m/s. With the increase of flow velocity in the corrosion products gradually increase content of element of oxygen has a certain influence on erosion. Corrosion rate of Q235 carbon steel increases with the increase of flow velocity corrosion medium. Molecular mass transfer flux greatly increase with velocity increase, which lead to corrosion rate increase, at the same. Corrosion products of surface on the carbon steel offed as shear stress on the carbon steel surface increase. The corrosion rate of carbon steel equal to 0.0045mm/a at the velocity(Om/s, 1m/s,4m/s,8 m/s,12m/s,15m/s), when 15mg/L amide imidazoline corrosion inhibitor was added to HCl solution (250mg/L, 500mg/L,750mg/L) and acetic acid solution (250mg/L,500mg/L,750mg/L). Carbon steel sheet surface was smooth, almost no surface corrosion. The corrosion of carbon steel can be alleviated obviously by the inhibitor of imidazoline amide in a flow state. |
