海底掺氢天然气管道的泄漏扩散模拟

Leakage and diffusion simulation of submarine hydrogen-blended natural gas pipeline

【目的】泄漏是海底天然气管道最常见的安全事故,当采用海底天然气管道进行掺氢输送时,研究掺氢对海底天然气泄漏扩散演化过程的影响具有重要意义。【方法】采用数值模拟方法,分别对海底掺氢天然气管道的锚断泄漏与小孔泄漏两种典型泄漏场景进行研究,分析掺氢比、海水深度、管道埋深、泄漏孔径等关键因素对掺氢天然气泄漏扩散的影响规律。【结果】对于海底掺氢天然气管道,无论是锚断泄漏还是小孔泄漏,海水流速均会影响掺氢天然气沿水平及竖直方向的扩散距离。对于海底管道锚断泄漏,掺氢比的增加会增大泄漏掺氢天然气在海水中的扩散速率,相同泄漏时间下掺氢天然气沿水平及竖直方向的扩散距离均会比纯天然气增加;泄漏的掺氢天然气溢出海面的时间与管道埋深正相关,管道在海床中埋设越深,掺氢天然气溢出海面所需的时间越长。对于海底管道小孔泄漏,泄漏的掺氢天然气由于受海床泥沙阻力的影响,扩散过程相对锚断泄漏变缓,掺氢比的增加同样会增大掺氢天然气沿水平及竖直方向的扩散距离;泄漏孔径的尺寸对泄漏扩散影响明显,随着泄漏孔径的增大,相同泄漏时间下掺氢天然气的扩散距离增加。【结论】相关研究可为海底掺氢天然气管道的安全输送与泄漏防护提供参考。

[Objective]Among various safety accidents associated with submarine natural gas pipelines,leakage remains a prevalent concern due to its high frequency.As the transmission of hydrogen-blended natural gas becomes more common through these pipelines,studying the impact of hydrogen blending on the evolution of leakage and diffusion is of utmost importance.[Methods]Two typical leakage scenarios of submarine hydrogen-blended natural gas pipelines were studied through numerical simulations:anchor break leakage and aperture leakage.The analysis focused on the influence patterns of crucial factors such as hydrogen blending ratios,seawater depths,pipeline burial depths,and sizes of leakage apertures on the leakage and diffusion of these pipelines.[Results]In both anchor break leakage and aperture leakage scenarios of submarine hydrogen-blended natural gas pipelines,it was observed that seawater velocity influenced the horizontal and vertical diffusion distances of leaking hydrogen-blended natural gas.In the anchor break leakage scenario,the diffusion of leaking hydrogen-blended natural gas in seawater accelerated with a rise in the hydrogen blending ratio.This led to greater horizontal and vertical diffusion distances for leaking hydrogen-blended natural gas compared to pure natural gas within the same leakage duration.Additionally,a direct correlation was noted between the time taken for leaking hydrogen-blended natural gas to reach the sea surface and the pipeline burial depth.Deeper pipeline burial depths led to longer travel times for leaking hydrogen-blended natural gas to reach the sea surface.In the aperture leakage scenarios,the diffusion process of leaking hydrogen-blended natural gas exhibited a deceleration compared to anchor break leakage,primarily attributed to the resistance posed by seabed sediment.Furthermore,an increase in the hydrogen blending ratio also resulted in extended horizontal and vertical diffusion distances of leaking hydrogen-blended natural gas.Notably,a distinct impact on leakage diffusion was identified across varying leakage aperture sizes.Larger leakage apertures allowed leaking hydrogen-blended natural gas to diffuse over greater distances within the same leakage duration.[Conclusion]The research findings serve as a reference for enhancing the safety of transmission and preventing leakage in submarine hydrogen-blended natural gas pipelines.