Energy, Exergy, and Economic (3E) Analysis of Boil-Off Gas Re-Liquefaction Systems Using LNG Cold Energy for LNG-Fueled Ships

Liquefied natural gas (LNG)-fueled ships have the effect of reducing most pollutants, which is advantageous for responding to strict regulations. Because boil-off gas (BOG) is generated in the LNG storage tank of an LNG-fueled ship, a BOG re-liquefaction system is required. The representative system...

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Bibliographic Details
Published inJournal of marine science and engineering Vol. 11; no. 3; p. 587
Main Authors Kim, Jun-Seong, Kim, Do-Yeop
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.03.2023
Subjects
3E analysis
Bogs
boil-off gas
Brayton cycle
Comparative analysis
Economic analysis
Economic aspects
Economics
Efficiency
Energy
Energy consumption
Exergy
Genetic algorithms
Liquefaction
Liquefied natural gas
LNG cold energy
LNG-fueled ship
Natural gas
Nitrogen
Pollution control
re-liquefaction system
Rivers
Shipping industry
Ships
Specific energy
Storage tanks
Sulfur content
Thermodynamics
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Summary:Liquefied natural gas (LNG)-fueled ships have the effect of reducing most pollutants, which is advantageous for responding to strict regulations. Because boil-off gas (BOG) is generated in the LNG storage tank of an LNG-fueled ship, a BOG re-liquefaction system is required. The representative systems for LNG-fueled ships were proposed by Kwak and Shen, but their exergy efficiencies were only 19.6% and 24.9%, respectively. To improve the system, this paper proposes novel BOG re-liquefaction systems combined with the fuel gas supply system. The systems utilize LNG cold energy in the BOG stream and N2 reverse Brayton cycle, respectively. The proposed systems were simulated using a commercial program and were optimized using a genetic algorithm. The results of energy, exergy, and economic (3E) analyses performed for comprehensive evaluation of the proposed system show that the system in which LNG cold energy is applied to the BOG stream has the best performance. Specific energy consumption, exergy efficiency, and total annual costs of this system were improved by up to 78.6%, 69.2%, and 68.2%, respectively, compared to those of the existing systems. The overwhelmingly superior system is expected to greatly contribute to the improvement of the BOG re-liquefaction system for LNG-fueled ships.
ISSN:2077-1312
2077-1312
DOI:10.3390/jmse11030587