Analysis of erosion wear behavior differences for 90° elbows in hydrogen and natural gas pipeline stations

ObjectiveThe application of energy pipelines is shifting to the transportation of hydrogen in the context of energy transition, however, research on erosion caused by particles in hydrogen remains limited. At present, the construction and operation of hydrogen pipelines worldwide are still in the early stages. Therefore, no statistical data on impurities inside the pipelines are available.Investigating the erosion of hydrogen pipeline elbows using data on impurity particle size and mass flow in natural gas stations is crucial for ensuring the safe operation of hydrogen pipelines. MethodsRegarding the difference in erosion wear between hydrogen and natural gas pipeline stations, a numerical model was established using Fluent based on the discrete phase model to simulate the erosion process of the 90° elbow of 200 mm diameter pipelines with a bend-to-diameter ratio of 1.5. The effects of flow direction, gas composition, gas flow velocity, impurity particle diameter, and impurity particle mass flow rate on erosion wear morphology and rate were examined. Additionally, a user-defined function (UDF) was utilized to extract particle collision information at the wall surface, allowing for the analysis of the coupling effects of impact angle, impact velocity, and impact frequency on differences in erosion morphology and rate. ResultsSevere erosion areas were predominantly found in straight pipeline segments and on the inner and outer arc surfaces of the elbow exit segments, shifting with changes in particle Stokes number. In pure hydrogen stations, the maximum erosion rate of the elbow increased exponentially with fluid flow velocity and approximately linearly with mass flow rate. The erosion rate also exhibited a two-stage characteristic, initially increasing slowly before rising rapidly with increasing particle size. When the pipeline transportation medium was hydrogen, the maximum erosion rate of the elbow was significantly greater than that of methane pipelines under the same energy supply intensity, with a critical particle size of 30 μm identified for the pure hydrogen pipeline. Beyond this critical value, the elbow’s maximum erosion rate exhibited a marked increase. Additionally, when the concentration of particulate matter in the pipe was below 100 mg/m³ and particle size was under 10 μm, the flow velocity in the hydrogen station could reach 30 m/s without significantly compromising pipeline safety. ConclusionThrough multi-scale coupled analysis, the erosion mechanism of hydrogen pipelines has been elucidated, clarifying the influence of the interaction between medium physical properties and particle dynamics on erosion behavior. This research offers a theoretical reference for regulating flow velocity and impurity content in hydrogen stations, reducing the risk of elbow failure, and establishing a foundation for the reliability design and standard formulation of hydrogen energy infrastructure.