암반동굴식 지하 LNG 저장 시스템 설계를 위한 기화율의 산정

A new underground LNG storage concept in the rock mass has been developed by combining underground cavern construction and new ice-ring barrier technologies with the conventional cryogenic insulation system. Technical feasibility of the storage system has been verified through construction and operation of the pilot storage cavern and a full-scale project is expected to start in the near future. One of the most important issues in the LNG storage system is the operational efficiency of the storage to minimize heat loss during a long period of operation due to the cryogenic heat transfer. This paper presents several important results of heat transfer and coupled hydro-thermal analyses by a finite element code Temp/W and Seep/W. A series of heat transfer analyses for full-scale caverns were performed to determine design parameters such as boil-off gas ratio (BOR), insulation thickness and pillar width. The result of the coupled hydro-mechanical analysis showed that BOR for underground storage system remains at about 0.04%/day during the early stage of the operation. This value could be even much lower when the discontinuities in the rock masses are taken into consideration.