Objective The leakage and diffusion rules of natural gas long-distance transportation pipelines caused by hydrogen blending under multi-factor coupling are explored.

Methods Taking the West-East Gas Transmission Second Line Project as the research object, Fluent software is used to establish a two-dimensional plane leakage and diffusion model of the pipeline, and the effects of hydrogen blending ratio, leakage aperture, wind speed and atmospheric temperature on the leakage and diffusion of hydrogen blended natural gas are analyzed by single-factor and multi-factor coupling.

Results As the proportion of hydrogen blending increases, the concentration and width of the methane diffusion region decreases, while the opposite is for hydrogen. The concentration and extent of hydrogen blended natural gas diffusion increase with the enlargement of leak aperture. With the increase of wind speed, the concentration of diffusion after the leakage of hydrogen blended natural gas increases, and the distribution gradually shifts downwind direction, while the diffusion height decreases. The influence of atmospheric temperature on the leakage and diffusion of hydrogen blended natural gas is not significant. The influence degree of different factors on the leakage and diffusion range of hydrogen blended natural gas pipeline is leakage aperture > wind speed > hydrogen blending ratio > atmospheric temperature.

Conclusions Among the four influencing factors, the leakage aperture has the greatest influence on the leakage and diffusion of hydrogen blended natural gas pipelines. Therefore, the emphasis should be focused on preventing the leakage caused by pipeline cracking and perforation caused by corrosion and other factors of hydrogen blended natural gas pipelines.