Speaker
Description
Abstract
Vacuum insulation is commonly used in cryogenic liquid storage, in the ground applications, because of its excellent insulation performance. However, the accidental loss of insulating vacuum might result in significant boil-off of the stored liquid. The loss of the stored liquid through boil-off not only impacts energy efficiency but also poses a serious safety concern. The hazards associated with the storage of cryogenic liquids must be thoroughly considered to protect humans, assets, and the environment. Quantitative risk assessment (QRA) is an essential tool for evaluating the risks. As a critical step in QRA, the consequence estimation process requires the evaluation of the boil-off rate of the liquid in the case of vacuum failure to analyze incident outcomes. In this study, the boil-off rate of liquid nitrogen stored in a double-walled vacuum insulated tank in the case of vacuum loss was numerically and experimentally investigated. Heat sources for the liquid boil-off included solar radiation and convection from the ambient air. A numerical model was developed to take into account all heat transfer phenomena between the liquid and the surroundings. Significantly, the convection of air in the gap between the inner and outer tank walls was carefully considered. Besides, a physical model was built and experiments were conducted for both intact and damaged vacuum insulation cases. The surface temperature of the outer tank wall and the boil-off rate of the liquid were measured. The model proved its excellent accuracy through the validation against the experimental data. Significantly, it was observed that the boil-off rate decreased approximately linearly over time. The findings of this study are expected to enhance the understanding of the boil-off behavior of cryogenic liquids in the case of the failure of vacuum insulation and also provide an efficient numerical tool for analyzing the incident outcomes for consequence estimation as a part of QRA.
Keywords: Cryogenic liquid; storage; vacuum insulation; boil-off; quantitative risk assessment.
Acknowledgments
This research was supported by a research program funded by the Ministry of Trade, Industry and Energy of the Republic of Korea and Korea Institute of Energy Technology Evaluation and Planning (Grant number: 20215810100020).
| Submitters Country | Republic of Korea |
|---|
