Erosion resulting from the presence of sand is a complex phenomenon even in a single-phase flow. The complexity of the problem increases significantly in multiphase flow due to existence of different flow patterns. Earlier models for predicting erosion in multiphase flow were significantly based on empirical data and the accuracy of those models was limited to the flow conditions of the experiments. A mechanistic model has been developed for predicting erosion in multiphase flow in elbows that are downstream of vertical pipes considering the effects of particle velocities in gas and liquid phases of the flow. As the mechanistic model is based on physics of multiphase flow, it is expected to be more general than the models that are solely based on empirical information. The predictions for an elbow geometry were compared with erosion experiments conducted in multiphase flow showing good agreement.
Erosion caused by entrained solid particles is a major problem in fluid handling equipment used in several industries. In the oil and gas industry, sand production from the oil and gas wells may cause considerable erosional damage in the well tubing, piping, fittings, and other equipment. The momentum of the solid particles in the production fluid results in particles impinging on the inner surfaces of the pipes, fittings and valves resulting in material loss from the surface that leads to production loss, operating problems and lower reliability of the system. In coal gasification, erosion problems are added to corrosion causing severe erosion to valves and pipe fittings [1]. Erosion of slurry pipelines in transportation of raw solid materials, such as iron ore, coal and potash is a significant problem in the mining industry [2].
Solid particle erosion is a process by which material is removed from a solid surface due to mechanical effects such as impingement of solid particles on the surface [3]. The erosion phenomenon is highly complicated and a wide range of parameters, such as production flow rate, sand rate, fluid properties, flow regime, solid particle properties, wall material of the equipment, and geometry of the equipment affect the erosion severity [4]. To prevent process equipment failure and downtime, it is critical to predict damage that may occur due to erosion in the process equipment and piping.
Erosion prediction in multiphase flow is a complex problem due to lack of understanding of the spatial distribution of the solid particles in the flow and their corresponding impact forces that cause erosion on the metal surfaces. The solid particle impact velocity depends upon the geometry of the pipe or fitting, carrying fluid velocity, flow pattern, pipe, inclination angles, solid concentration, as well as particle shape, size and distributions in the flow. Most of the erosion prediction models are based on single-phase liquid or gas as the particle carrying fluid. In oil and gas wells, the fluid is a mixture of gas, liquid and sand that requires a multiphase erosion prediction model. The complexity of erosion prediction increases significantly for multiphase flow when gas, liquid and solids are present in the flow. In contrast to single-phase flow, multiphase flow has different flow patterns depending upon the gas, liquid and solid flow rates, pipe size, inclination angles, and fluid properties. Although the authors realize the complexity of the problem
