Experimental study on leakage temperature field of hydrogen blending into natural gas buried pipeline

Hydrogen blending into natural gas is a feasible approach to realize the low-carbon energy structure. The impact of the hydrogen blending ratio on the leakage characteristics of buried gas pipelines determines the safety of pipeline operations. In this study, we investigated the influence of the hydrogen blending ratio on the soil temperature field after the buried gas pipeline leak and the detection range of fiber optic sensors through a field test and numerical simulation. A critical flow model based on the Peng-Robinson (PR) equation and a soil diffusion model based on simplified throttling were established for the microleakage and diffusion stages of the buried pipeline. Furthermore, the soil temperature variation after the buried pipeline leak and the prediction model of cooling capacity caused by gas leakage were obtained. In addition, the leakage experiments were performed to evaluate the impact of hydrogen blending ratio, pipeline operation pressure, and leak direction, as well as to achieve the soil temperature field distribution near the leak point. The following conclusions can be drawn: (1) Soil temperature decreases as the hydrogen blending ratio increases; (2) The detection range of the fiber optic sensors increases as the hydrogen blending ratio increases, ensuring the applicability of the existing fiber optic detection system for detecting hydrogen blending pipeline leaks. The findings provide a valuable research topic for hydrogen pipeline leak detection. •An experiment on the leakage of hydrogen - doped natural gas from buried pipeline is carried out.•A flow model based on PR equation of state is established for leakage prediction.•Calculation method of cooling capacity caused by gas injection based on soil temperature distribution.•The distribution of soil temperature and temperature change rate near the leakage.