Investigation on natural gas leakage and diffusion characteristics based on CFD

The transportation of hazardous gases such as natural gas and hydrogen through buried pipelines is widely considered the most economically safe method. In recent years, due to the extension of service time and material aging, gas leakage incidents have become more common during transportation, leading to significant hazards such as fires and explosions. This paper aims to study the leakage and diffusion behavior of buried pipelines, help emergency personnel more accurately determine the areas that may be affected, and provide theoretical support for risk assessment and emergency planning of natural gas pipeline leaks. In this paper, the influence of different factors on the diffusion law of gas leakage is analyzed, and the factors that have the greatest influence on the diffusion are obtained through exploratory data analysis. Findings reveal pressure, leak size and soil temperature are positively correlated with methane concentration and dangerous area. Conversely, soil moisture negatively correlates with methane concentration and lateral diffusion distance. Soil type significantly impacts methane concentration, with sand facilitating the most diffusion, followed by loam, and least in clay. Therefore, soil compaction is recommended to mitigate gas diffusion rates during leaks, reducing hazardous zone extents. Additionally, the study delves into the emerging trend of transporting natural gas blended with hydrogen. Higher hydrogen ratios result in quicker reaching of Lower Explosive Limit and larger hazardous zones. In order to study the complex dynamics of multi-source leakage scenarios, two pipeline leakage diffusion simulations are carried out in this paper. The results showed increased horizontal spacing reduces maximum methane concentrations on the surface. However, this also enlarges gas alert and hazardous zone areas, heightening the risk of explosionrelated incidents. These conclusions provide a theoretical framework for risk assessment and emergency treatment of pipeline leakage.