Numerical simulation of carbon dioxide corrosion under flow conditions in an elbow

Abstract

A computational fluid dynamics (CFD)‐based method combined with water chemistry and electrochemical reaction calculation is developed to investigate the effect of fluid flow on carbon dioxide corrosion in an elbow. The mass transfer of reactants and products influenced by flow during corrosion is revealed visually by distribution of main species concentration. The results show that the distributions of main species concentration and corrosion rate on the bare steel surface are in good accordance with the distribution of flow velocity. The maximum corrosion rate appears at the entrance on inner side wall of the elbow, and the corrosion rate decreases along the flow direction. Near the exit of the elbow, the secondary flow arises and enhances the mass transfer as well as the corrosion rate. According to the saturation value, the iron carbonate is more likely to precipitate at the inner side wall near the exit of the elbow. The model is validated by the good agreement between simulation results and published experimental data in prediction of hazardous corrosion region and the regional corrosion rate of the elbow.

Investigation of corrosion behavior at elbow by array electrode and computational fluid dynamics simulation

“…Finally, the FAC rate located at different positions of 90°elbow could be predicted with the help of the corresponding FAC rate of the straight pipe. Moreover, the FAC rate of the straight pipe under steady-state condition has been well predicted by Equations (9)- (13) and the validity of the predicted FAC rate of the straight pipe has been confirmed by previous work. [7,10,11] 3.3 | CFD simulation…”

“…The validity of the geometrical factors obtained by this method above has been confirmed in previous reports. [15,40] Moreover, the ferrous species concentration could be obtained by Equation (13). As a result, the FAC rate of 90°elbow located in different positions could be determined.…”

“…The predicted results are consistent with the comprehensive inspection values in a Taiwan pressurized water reactor (PWR). [12] Moreover, Chen et al [13] suggested a computational fluid dynamics (CFD)-based method considering the water chemistry and electrochemical reaction to investigate the effect of FAC at the elbow and revealed the secondary flow induced by the elbow is closely related to the mass transfer process. Sanama et al [14] established an analytical model to evaluate the FAC rate downstream of the orifice, which can accurately predict the position of the maximum FAC rate.…”

Experimental Investigation on Corrosion Behavior of X80 Pipeline Steel under Carbon Dioxide Aqueous Conditions

“…A mixed solution with concentrations of 0.6 mol L –1 sodium chloride and 1 mol L –1 sodium bicarbonate is used to study the corrosion behavior of X80 in the carbon dioxide-containing alkaline environment. The pH of this testing solution is 7.6, which is determined by the water chemistry calculation underlying carbon dioxide corrosion, which performs well in our previous work . The EIS measurement under this condition is demonstrated in Figure .…”

“…The pH of this testing solution is 7.6, which is determined by the water chemistry calculation underlying carbon dioxide corrosion, which performs well in our previous work. 34 The EIS measurement under this condition is demonstrated in Figure 10. In alkaline solution, the first step of iron dissolution could be assumed as given in eq 5.…”