Methane flame propagation characteristics in pipelines based on the synergistic effect of lateral venting and N₂ injection

ABSTRACT

This study explores the effective combination of nitrogen injection and lateral venting in a horizontal pipe to limit flame propagation and, thus, lessen damage from gas explosion. Two nitrogen nozzles were placed downstream of the vents, and the lateral vent was mounted on the upper surface of the pipe for the experiment. According to the results, lateral venting can significantly slow flame propagation speed. The flame propagation speed was lowered from 4.8 m/s to 0.5 m/s, a reduction of 89.5%, giving enough time for the creation of the N₂ flame arresting zone. When the nitrogen pressure reaches or surpasses 0.3 MPa, the nitrogen injection can stop the flame from moving farther downstream of the pressure release port. The study discovered that for horizontal pipes, the synergistic effect of lateral venting and inert gas injection is more effective at preventing methane-air explosions than either mitigation method alone (i.e. ventilation alone or inert gas injection alone). The study’s findings may offer theoretical support for the prevention and control of flame spread during gas explosions in mines.

KEYWORDS:

• Safety engineering
• explosion
• methane
• venting
• Quench

Acknowledgements

This work is supported by the Science and Technology Project of the State Grid Corporation of China (8000-201918445A-0-0-00).

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Nomenclature

$v_{yes}$	=	Flame propagation velocity in a semi-closed pipe with lateral venting
$v_{no}$	=	Flame propagation speed in semi-enclosed pipes without lateral venting
$\mathrm{\Delta }v$	=	Difference in flame propagation speed with and without lateral venting
$\mathrm{\Delta }p$	=	The pressure difference between the combustion region and the unburned area

Additional information

Funding

The work was supported by the Science and Technology Project of the State Grid Corporation of China [8000-201918445A-0-0-00].

Notes on contributors

Yang Liu

Yang Liu was born in July 1994. In 2020, he entered China University of Mining and Technology(Beijing) to study for a doctorate. His research interests include safety science and engineering, fire dynamics, fire protection theory, etc.

Peng Chen

Peng Chen is a professor at China University of Mining and Technology (Beijing). His research interests include fire dynamics.

Zhixi Fu

Zhixi Fu is a student at China University of Mining and Technology (Beijing). She research interests include fire protection theory.

Xu Zhai

Xu Zhai is a student at China University of Mining and Technology (Beijing). His research interests include fire dynamics.

Shaodong Sun

Shaodong Sun is a student at China University of Mining and Technology (Beijing). His research interests include fire dynamics.