EXPERIMENTS AND MECHANISTIC MODELING OF SAND EROSION OF 90° ELBOWS IN LIQUID- DOMINATED MULTIPHASE FLOWS

Pipeline erosion is a common phenomenon in various industries dealing with the transportation of fluids, especially those containing solid particles. Identifying wall thickness loss of pipes and fittings due to solid particle erosion becomes very challenging under multiphase gas-liquid flow conditions which are very common in the oil and gas industry. For instance, it is of utmost importance for operators in the oil and gas industry to make accurate predictions about the internal erosion of elbows within their systems. In this study, erosion measurements were carried out on a standard 50.8 mm (2-inch) stainless steel 316 elbow to assess mechanistic models for predicting erosion rates for elbows in vertical slug-churn flow with sand, a common occurrence in liquid-dominated production systems. Erosion experiments were performed in a large-scale multiphase flow loop, adjusting the velocities of gas (air) and liquid (water), and using particles of 75, 150 and 300 mu m in size. In the experiments, superficial liquid and gas velocities ranged from 2 to 5.9 m/s and from 5.8 to 17.5 m/s, respectively. These tests were conducted in an upward vertical direction. Paint removal experiments were conducted to determine the erosion patterns and hot spots of erosion using acrylic elbows. Erosion data was collected using a non-intrusive ultrasonic technique. It was observed that the location of maximum erosion changes as the superficial velocities change. Finally, a semi-mechanistic model based on a drift-flux approach was able to predict the observed maximum erosion rates with an acceptable degree of accuracy. Comparisons with existing models in the literature are also presented.