A unified explicit correlation of predicting the sand erosion in elbows for gas and annular flows based on probability analysis

Abstract

The elbows are susceptible to the sand erosion during the transportation of oil and gas, especially for gas and annular flows. The objective of present work is to provide a simple and efficient method for predicting the sand erosion in elbows for both gas and annular flows. First, mechanistic analyses of the sand erosion in annular flow are conducted, and an erosion reduction coefficient is deduced to unify the erosion calculation in gas and annular flows. The erosion reduction coefficient is verified by a series of simulations with varying parameters, such as the superficial gas velocity, superficial liquid velocity, radius of curvature, pipe diameter, particle diameter and hardness of pipe wall. Then, the simulation results are employed to investigate the effects of second collision on the total erosion. Based on the investigation, two enhancement coefficients are proposed to estimate the contribution of second collision to the maximum penetration ratio and the most serious erosion position. Finally, by combining the above coefficients and the probability erosion models, a unified explicit correlation is derived for predicting the sand erosion in elbows and examined by the experimental data in gas and annular flows. The comparative study indicates that the new correlation performs well not only in simplifying the probability erosion models but also in predicting the maximum penetration ratio and the most serious erosion position.