Erosion critical characteristics of REAC outlet elbow pipe based on similarity theory

During the process of reconstruction and enlargement of petrochemical unit and crude oil degradation inland,the unscheduled shutdown of oil processing enterprises caused by flow-induced corrosion occurred universally,which affected enterprise production,surrounding environment and public safety seriously.In view of the frequently failure for the outlet elbow piping system of REAC,the mechanism of pipeline erosion destroy which dues to corrosion and multiphase flow interaction was studied.The model elbow pipe was designed and the experimental parameters were determined based on ascertained similarity criterion and obtained characteristic data.Moreover,the simulated erosion experiments were performed on the self-designed loop test apparatus for multiphase flow erosion-corrosion,and the erosion critical characteristic parameters of model elbow pipe were obtained by computational fluid dynamics(CFD) simulation on the process of corrosion.The simulated erosion test and the result of model elbow pipe simulation show that the erosion critical velocity of model origin is 7.93 m·s-1,and the maximum shear stress of model elbow is 2.21 Pa,which tend to agree to the position of maximum water phase. Furthermore,the mathematical equation that reflects the relationship between the critical characteristic of prototype model and that of test model were established by dimensional analysis method.The correction coefficient of similarity theory was therefore solved,and the erosion critical characteristics of real case were corrected and acquired.The reliability and accuracy of the tests on erosion critical characteristics and the results of amendments were verified by the thickness measurement data,and the critical shear stress that cased erosion-corrosion was about 1.79 Pa.The erosion tests and analysis methods were innovative,which provided scientific theories and experimental methods for the multiphase flow erosion prediction of various pressure pipe related to different industries.