利用管道输送氢气是较为经济的中长距离氢能储运模式。相比新建纯氢管道或天然气管道掺氢输送,利用在役天然气管道改输氢气具有灵活利用管道资产、促进氢能高效利用、完善能源替代等优点。近年来,国内外开展了新建氢气管道的实践运行,但尚未大规模开展在役天然气管道改输氢气的研究。基于氢气与天然气特性比对,梳理了在役天然气管道改输氢气的评价技术要点,开展了运行压力、介质流速、安全保障等方面的分析探讨。研究表明,现行国外标准规范通过限制环向应力改输氢气管道以进一步提高管道安全性,但可能降低管道的最高运行压力;在役天然气管道改输氢气后需关注:提高介质流速应重视杂质控制、站场插入式仪表涡激振动等问题;氢气泄漏后的潜在影响范围有所缩小,站场外部防火间距评价与调整还需开展系统论证;管道放空系统热辐射范围减小,放空系统的爆燃、爆轰风险应予以控制。研究成果为后续在役天然气管道改输氢气评价提供了借鉴。

Using pipelines to transport hydrogen is a relatively economical mid to long-distance hydrogen transmission option. Compared with the construction of new pure hydrogen pipelines or the option of having hydrogen blended into natural gas pipelines for transmission, the use of existing pipelines to transport hydrogen has the advantages of flexible utilization of pipeline assets, promoting efficient use of hydrogen energy, and improving energy substitution. In recent years, the actual operation of new hydrogen pipelines has been carried out both at home and abroad. However, comprehensive, large-scale research and the practice of converting existing natural gas pipelines to hydrogen transmission have not yet been carried out. Basing on the comparison of the characteristics of hydrogen and natural gas, this paper outlines the key technical points for evaluating conversion of existing pipelines for hydrogen transmission. It also analyzes and discusses operating pressure, transmission medium flow rate, safety assurance, and other process and safety issues. The study shows that the current international codes and standards have proposed a method to further improve the safety of pipelines by limiting the hoop stress for pipelines converted into hydrogen service, but this reduces the maximum operating pressure of the pipeline. Following the transition to hydrogen transmission, attention should be paid to issues such as impurity control and vortex-induced vibration of inserted instruments in the station. Once converted into hydrogen service, the potential impact range following a leak is reduced, but the evaluation and adjustment of the external fire protection separation distance of the station still need to be systematically demonstrated. With hydrogen as the new medium, the thermal radiation range of the pipeline vent and flare system is reduced, and the risk of deflagration and detonation of the vent and flare system should be controlled. The research results can provide reference for the subsequent evaluation of converting existing natural gas pipelines for hydrogen transmission.