Effect of Sand Distribution on Erosion in Annular Three-Phase Flow

Abstract

Erosion in multiphase flow with entrained solid particles is a complex phenomenon due to existence of different flow patterns. Erosion experiments were conducted on an elbow specimen in a one-inch multiphase flow loop with gas, liquid and sand. Two different elbow specimens were used in the experiments. One placed downstream of a horizontal test section and one downstream of a vertical test section. Erosion tests were conducted at different gas and liquid velocities that showed a difference in erosion rates between the horizontal and vertical specimens. In order to better understand erosion results, the distribution of solid particles within the horizontal and vertical pipes just upstream of the elbows was measured across the pipe with a pitot probe. The results indicate that the distribution of sand in the pipe cross-section plays an important role in the erosion process due to the differences in velocities of the sand particles moving in the gas core and in the liquid film of the annular flow. It is observed that sand distribution in the horizontal test section is different than the sand distribution in the vertical test section for the same gas and liquid velocities. Therefore, the distribution of sand particles affects erosion test results. Based on these observations, a new mechanistic model has been developed to predict erosion in annular flow considering the effects of sand particle distribution and particle velocities in the annular film and gas core region. The experimental erosion results compare well with the model predictions.