Journal of the Korean Society of Safety (한국안전학회지)

The Korean Society of Safety (한국안전학회)
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A Study on the Properties of Nitrogen Purging in Liquefied Hydrogen Vent Pipes

액화수소 벤트 배관의 질소 퍼지에 대한 적정성 연구

  • Myoung Sun Wu (Department of Safety Engineering, Pukyong National University) ;
  • Chang Jun Lee (Department of Safety Engineering, Pukyong National University)
  • 우명선 (부경대학교 안전공학과) ;
  • 이창준 (부경대학교 안전공학과)
  • Received : 2023.11.29
  • Accepted : 2024.06.14
  • Published : 2024.06.30
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Abstract

Hydrogen is one of the most popular eco-friendly energy sources for reducing global warming. To use hydrogen as a conventional fuel, liquid hydrogen plants should introduce waste hydrogen treatment processes. A major safety issue of liquid hydrogen plants is choosing the most suitable purge gas to use in case of an accident. A purge gas prevents the formation of explosive mixed gases in the vent header. In general, nitrogen is the main purge gas used in chemical plants. Nitrogen has a freezing point of -210℃, which is higher than the boiling point of hydrogen. Helium, with a freezing point lower than hydrogen, is instead recommended as a purge gas of the vent header during hydrogen liquefaction. However, helium is roughly 100 times more expensive than nitrogen. To address this issue, this study uses simulations to investigate safe conditions for introducing nitrogen as the purge gas during hydrogen liquefaction. The temperature change from the safety valve to the vent header is evaluated when the external temperature of the safety valve discharge pipe is at 5℃, 10℃, and 20℃. Additionally, the most optimal length for a discharge pipe according to pipe diameter is investigated.

Keywords

Acknowledgement

This work was supported by a Research Grant of Pukyong National University (2023-06690001).

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