Journal of Navigation and Port Research (한국항해항만학회지)

Korean Institute of Navigation and Port Research (한국항해항만학회)
권호 표지
DOI QR코드

DOI QR Code

Design and Assessment of Reliquefaction System According to Boil Off Gas Reliquefaction Rate of Liquefied Hydrogen Carrier

액화수소 운반선의 증발가스 재액화 비율에 따른 재액화 시스템의 설계 및 평가

  • Cho, Wook-Rae (Korean Register) ;
  • Lee, Hyun-Yong (Korean Register) ;
  • Ryu, Bo-Rim (Department of Marine System Engineering, Graduate School, Korea Maritime & Ocean University) ;
  • Kang, Ho-Keun (Division of Marine System Engineering, Korea Maritime & Ocean University)
  • Received : 2020.06.08
  • Accepted : 2020.07.15
  • Published : 2020.08.31
Download PDF
⟨ Previous Next ⟩

Abstract

BOG (Boil Off Gas) generation is unavoidable in the liquefied hydrogen carrier, and proper measures are necessary to prevent pressure problems inside the cargo tank. The BOG can be used as propulsion fuel for ships, and the remaining parts used for propulsion must be effectively managed, such as in the form of reliquefying or burning. This study proposes an BOG reliquefaction system optimized for a 160,000 m3 liquefied hydrogen carrier with a hydrogen propulsion system. The system comprises a hydrogen compression and helium refrigerant section, and increases the efficiency by effectively using the cold energy of the BOG discharged from the cargo tank. In this study, the system was evaluated through the exergy efficiency and SEC (Specific Energy Consumption) analysis according to the rate of the reliquefaction of the BOG while the hydrogen BOG with a supply temperature of -220℃ entered the reliquefaction system. As a result, it showed SEC of 4.11 kWh/kgLH2 and exergy efficiency of 60.1% at the rate of reliquefaction of 20%. And the parametric study of the effects of varying the hydrogen compression pressure, inlet temperature of the hydrogen expander, and the feed hydrogen temperature was conducted.

액화 수소 운반선에서 증발가스의 발생은 불가피하며, 화물탱크 내부의 압력 문제를 피하기 위해 적절한 조치가 필요하다. 이 증발 가스는 선박의 추진연료로 사용 될 수 있으며, 추진에 사용되고 남은 나머지 부분은 재액화 또는 연소시키는 등 효과적으로 관리해야 한다. 본 연구에서는 수소 추진 시스템을 갖춘 160,000㎥ 액화 수소 운반선에 최적화된 증발 가스 재액화 시스템을 제안한다. 이 시스템은 수소 압축 및 헬륨 냉매 섹션으로 구성되고, 화물탱크로부터 배출되는 증발가스의 냉열을 효과적으로 활용하여 효율을 증가시켰다. 본 연구에서는 공급 온도 -220℃인 수소 증발가스가 재액화 시스템에 들어가는 상태에서 증발가스의 재액화 비율에 따른 엑서지 효율 및 에너지 소모율 (SEC, Specific Energy Consumption) 분석을 통해 시스템을 평가하였다. 그 결과 재액화 비율 20%에서 4.11kWh/kgLH2의 SEC와 60.1%의 엑서지 효율을 보여 주었다. 아울러, 수소 압축압력, 수소 팽창기의 입구온도, 공급 증발가스 온도변화에 따른 영향을 확인하였다.

Keywords

References

  1. Choi, D. K., Kang, J. K., Moon, Y., Jung, J., Kwon, O. and Kim, N. S.(2014). "Hybrid FGS system with partial Re-liquefaction unit for MEGI propelled LNG carrier.", In Gastech conf.
  2. Fernandez, I. A., Gomez, M. R., Gomez, J. R. and Lopez-Gonzalez, L. M.(2017), "H2 production by the steam reforming of excess boil off gas on LNG vessels." Energy Conversion and Management, 134, pp. 301-313. https://doi.org/10.1016/j.enconman.2016.12.047
  3. Gomez, J. R., Gomez, M. R., Bernal, J. L. and Insua, A. B.(2015), "Analysis and efficiency enhancement of a boil-off gas reliquefaction system with cascade cycle on board LNG carriers.", Energy Conversion and Management, 94, pp. 261-274. https://doi.org/10.1016/j.enconman.2015.01.074
  4. International Maritime Organization (IMO)(2016), Interim recommendations for carriage of liquefied hydrogen in bulk. Resolution MSC. 420(97).
  5. Lowesmith, B. J., Hankinson, G. and Chynoweth, S.(2014), "Safety issues of the liquefaction, storage and transportation of liquid hydrogen: An analysis of incidents and HAZIDS.", Int J Hydrogen Energy, 39, pp. 20516-20521. https://doi.org/10.1016/j.ijhydene.2014.08.002
  6. Peschka, W.(2012), Liquid hydrogen: fuel of the future, Springer-Verlag Wien: New York.
  7. Sadaghiani, M. S., Mehrpooya, M. and Ansarinasab, H.(2017), "Process development and exergy cost sensitivity analysis of a novel hydrogen liquefaction process.", Int J Hydrogen Energy, 42, pp. 29797-29819. https://doi.org/10.1016/j.ijhydene.2017.10.124
  8. Tan, H., Shan, S., Nie, Y. and Zhao, Q.(2018), "A new boil-off gas re-liquefaction system for LNG carriers based on dual mixed refrigerant cycle.", Cryogenics, 92, pp. 84-92. https://doi.org/10.1016/j.cryogenics.2018.04.009
  9. Tan, H., Zhao, Q., Sun, N. and Li, Y.(2016), "Enhancement of energy performance in a boil-off gas re-liquefaction system of LNG carriers using ejectors.", Energy Conversion and Management, 126, pp. 875-888. https://doi.org/10.1016/j.enconman.2016.08.031
  10. Tsatsaronis, G.(2007), "Definitions and nomenclature in exergy analysis and exergoeconomics.", Energy, 32, pp. 249-253. https://doi.org/10.1016/j.energy.2006.07.002
  11. Vatani, A., Mehrpooya, M. and Palizdar, A.(2014), "Energy and exergy analyses of five conventional liquefied natural gas processes.", Int J Energy Research, 38, pp. 1843-1863. https://doi.org/10.1002/er.3193
  12. Valenti, G. and Macchi, E.(2008), "Proposal of an innovative, high-efficiency, large-scale hydrogen liquefier.", Int J Hydrogen Energy, 33, pp. 3116-3121. https://doi.org/10.1016/j.ijhydene.2008.03.044
  13. Verfondern, K.(2008), Safety considerations on liquid hydrogen, vol. 10, Forschungszentrum Julich GmbH: Julich.
  14. Yuksel, Y. E., Ozturk, M. and Dincer, I.(2017), "Analysis and assessment of a novel hydrogen liquefaction process.", Int J Hydrogen Energy, 42, pp. 11429-11438. https://doi.org/10.1016/j.ijhydene.2017.03.064