Numerical investigation and estimation method of leakage behaviour for hydrogen-blended natural gas in overhead pipelines

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Blending hydrogen into existing natural gas pipelines can cause hydrogen embrittlement, which further leads to pipeline leakage and even serious explosions. Therefore, a mathematical-physical model is established for the leakage of hydrogen-blended natural gas (HBNG) based on species transport in this paper. The model is validated by the experimental values from the literature, with validation errors falling below 15%. The influence of different operating and structural parameters is analyzed on the leakage rate of HBNG. The results show that the leakage rate decreases with the hydrogen blending ratio increasing, it increases with an increase in leakage hole diameter and operating pressure, but it is poorly affected by the pipeline diameter and wall thickness. The orthogonal design is used in this simulation to analyse the effect of different factors on the leakage rate. The sensitivity for each factor ranks as follows: leakage hole diameter > hydrogen blending ratio > operating pressure > wall thickness > pipeline diameter. Finally, a new prediction model of leakage rate for HBNG is proposed, and the prediction deviation of that is less than 5%. The above results can be used as guidance for risk assessment and prevention of leakage accidents for HBNG in high-pressure overhead pipelines.