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- Title
混氢天然气管道放空自燃过程数值模拟分析.
- Authors
朱红钧; 李佳男; 陈俊文; 粟华忠; 唐 堂
- Abstract
Hydrogen-mixed natural gas transportation is one of the important ways for large-scale and long-distance hydrogen energy transportation. In the venting process of hydrogen-mixed natural gas, however, there are risks of detonation or deflagration, which exert excessive overpressure on the pipe wall, leading to its fracture. Therefore, it is in an urgent need to clarify the spontaneous combustion and flow field evolution process during the venting of hydrogen-mixed natural gas, so as to quantify the primary overpressure on the wall of the venting pipe. In this paper, the spontaneous combustion process during the venting of hydrogen-mixed natural gas pipeline is numerically simulated by using the computational fluid dynamics (CFD) method, the influence laws of different hydrogen concentrations on spontaneous combustion and pressure wave propagation are comparatively analyzed, and the deflagration mechanisms of hydrogenmixed natural gas in valve channels and venting pipes are revealed. And the following research results are obtained. First, high-pressure gas is propagated in the form of pressure wave in valve channels. During the propagation, it undergoes continuous collision, reflection and superimposition to form Mach ring structure, which heats the gas to the spontaneous combustion temperature, resulting in spontaneous combustion. Second, the phenomenon of deflagration appears in valve channels and venting pipes. In venting pipes, however, the energy of pressure wave decays rapidly, resulting in a significant reduction of temperature and hence the disappearance of gas combustion. Third, the larger the hydrogen concentration is, the faster the pressure wave propagates, the shorter time it takes to trigger the spontaneous combustion, and the greater the primary overpressure on the venting pipe wall . In conclusion, with given discharge pressure and valve opening, reducing the hydrogen concentration can effectively reduce the deflagration risks and the overpressure on the pipe wall. In actual engineering, the hydrogen mixing volume shall be controlled within a reasonable concentration range based on transportation economic costs and safety risks. These new understandings provide useful guidance for the safe venting of hydrogen-mixed natural gas pipelines and the large-scale mixed transportation of green hydrogen energy.
- Subjects
SPONTANEOUS combustion; NATURAL gas pipelines; NATURAL gas transportation; HYDROGEN as fuel; COMPUTATIONAL fluid dynamics; NATURAL gas; DETONATION waves
- Publication
Natural Gas Industry, 2023, Vol 43, Issue 9, p149
- ISSN
1000-0976
- Publication type
Article
- DOI
10.3787/j.issn.1000-0976.2023.09.015