随着综合管廊和氢能的快速发展,氢气混合天然气 (HBNG) 进入气室,就在眼前。然而,当前标准中对气室的所有安全要求都是针对天然气设计的,对 HBNG 的适用性尚不清楚。此外,现有的扩散模型大多假设 CH4/H2/Air 混合物是单组分均质气体,无法准确描述 CH4 和 H2 之间的扩散行为差异。本文提出了一种改进的 CH4/H2/Air 非理想多组分混合物扩散系数模型,该模型考虑了 CH4 和 H2 组分之间的相互作用。然后,建立了一个 200 m 长而窄的三维综合隧道模型,研究了不同通风条件下的 HBNG 浓度分布、警报响应时间和爆炸危险区域。分析了氢气混合比 (HBR) 、泄漏直径、管道运行压力、泄漏位置和通风频率对综合管廊泄漏扩散特性的影响。结果表明,在自然通风下,HBNG 以泄漏孔为中心对称向两侧扩散,1500 s后覆盖整个隔室。正常的机械通风会降低分布范围和 HBNG 浓度,泄漏的气体在 250 s 内覆盖下游的隔室。随着 HBR 的增加,泄漏位置下游每个监测点的 CH4/H2 混合物浓度增加,导致告警响应时间提前。当泄漏达到稳态时,HBR 为 5%、10%、15% 和 20% 的 CH4/H2 混合物浓度为 2.15%、4.14%、7.76% 和 10。比天然气高 97%。泄漏位置会影响危险区域范围,但对最终稳态下的 CH4/H2 混合物浓度影响不大。较大的泄漏直径和较高的管道运行压力会加速 HBNG 在综合管廊中的扩散速率。当管道运行压力增加到 1.6 MPa 时,当前 12 次/h 的最小事故通风频率不足以将 CH4/H2 混合物浓度降低到爆炸下限 (LEL) 以下。增加通风频率可以有效降低综合管廊内泄漏的气体浓度,因此建议将最低事故通风频率从 12 次/h 增加到 15 次/h。研究成果可指导综合管廊中 HBNG 管道的设计和安全管理。
"点击查看英文标题和摘要"
Study on multicomponent leakage and diffusion characteristics of hydrogen-blended natural gas in utility tunnels
With the rapid development of utility tunnels and hydrogen energy, hydrogen-blended natural gas (HBNG) enters gas compartments just around the corner. However, all safety requirements for gas compartments in current standards are designed for natural gas, and the applicability to HBNG is unclear. In addition, most of the existing diffusion models assume that the CH4/H2/Air mixture is single-component homogeneous gas, which cannot accurately describe the diffusion behavior differences between CH4 and H2. In this paper, an improved diffusion coefficient model for CH4/H2/Air non-ideal multi-component mixtures is proposed, which considers the interaction between CH4 and H2 components. After that, a 200 m long and narrow three-dimensional utility tunnel model is established to study the HBNG concentration distribution, alarm response time, and explosion hazardous area under different ventilation conditions. The effects of hydrogen blending ratio (HBR), leakage diameter, pipeline operating pressure, leakage location, and ventilation frequency on leakage and diffusion characteristics of utility tunnels are analyzed. The results show that under natural ventilation, the HBNG diffuses symmetrically to both sides with the leak hole as the center and covers the whole compartment after 1500 s. Normal mechanical ventilation reduces the distribution range and HBNG concentration, and the leaked gas covers the compartment downstream within 250 s. With the increase of HBR, the CH4/H2 mixture concentration increase at each monitoring point downstream of the leakage location, which causes the advance of the alarm response time. When the leakage reaches a steady state, the CH4/H2 mixture concentration for HBR of 5%, 10%, 15%, and 20% is 2.15%, 4.14%, 7.76%, and 10.97% higher than that of natural gas. The leakage location affects the hazardous area range, but little affects the CH4/H2 mixture concentration at the final steady state. The larger leakage diameter and the higher pipeline operating pressure can accelerate the HBNG diffusion rate in utility tunnels. When the pipeline operating pressure increases to 1.6 MPa, the current minimum accident ventilation frequency of 12 times/h is insufficient to reduce the CH4/H2 mixture concentration below the lower explosion limit (LEL). Increasing the ventilation frequency can effectively reduce the leaked gas concentration in utility tunnels, so it is recommended to increase the minimum accident ventilation frequency from 12 times/h to 15 times/h. The research results can guide the design and safety management of HBNG pipelines in utility tunnels.