Study on the diffusion characteristics of small hole leakage of high-sulfur natural gas in gathering and transmission pipelines

The high‑sulfur natural gas contains hydrogen sulfide, which is extremely corrosive and toxic. Its leakage can cause irreversible environmental consequences. This study establishes a high‑sulfur natural gas pipeline leakage model using the three-dimensional CFD numerical calculation method in FLACS. The influences of multiple factors on the extent of leak spread in high‑sulfur natural gas are analyzed. The results show that hydrogen sulfide content in high‑sulfur natural gas inhibits the gas diffusion range. The diffusion distance for 20 % hydrogen sulfide is 0.87 times that of 2 % hydrogen sulfide, and the diffusion height is reduced to 0.83 times due to its higher average molar mass. Pipeline pressure, leakage orifice diameter, and ambient temperature show positive correlations with diffusion distances in all three spatial dimensions. Ambient wind speed increases the horizontal dispersion but inhibits vertical diffusion. The downwind diffusion distance at 5 m/s wind speed is 1.2403 times that at 0.5 m/s, while the diffusion height is reduced to 0.5882 times.