Analysis Of Cryogenic Effect On Large LNG Storage Tanks

As the primary energy storage device of natural gas, the construction number of LNG(liquefied natural gas) storage tanks in our country is increasing. The LNG storage tank safety is very important for our national economic development and stable social life-as an important strategic energy reserve, if the LNG storage tank damage occurs, not only results in direct economic losses, but also leads to environmental pollution, fire and other secondary disasters. The consequences could be disastrous. LNG’s operating temperature is-162℃. Once the inner tank of LNG tank leaks, the prestressed concrete outer tank will suffer a huge low impact. This condition poses a threat to the structural safety of external tank.Because of the ultra-low-temperature characteristics of liquefied natural gas, in the process of design and construction the low-temperature characteristics of LNG storage tank must be fully considered. At presrnt, Study of LNG cryogenic storage tank at home and abroad mainly focused on the internal LNG’s thermal properties, the heat insulation performanc of tank, building construction technology and structure seismic performance while cryogenic effect is ignored. In this paper, based on the finite element numerical simulation method, the temperature field and structure performance of large LNG full containment storage tank which considers cryogenic effect are studied. The distribution law of temperature field and strsess field when LNG storage tank operates at low temperature are analyzed. Meanwhile, the failure mechanism of LNG storage tank on leak condition has been revealed. The main contents are as follows:Part 1: According to a domestic large-scale LNG storage tank prototype, the detailed LNG storage tank ANSYS finite element model which considers cryogenic effect has been established;Part 2: When operating normally, the cryogenic effect of LNG storage tank has been analyzed. The distribution of temperature field and stress field of LNG storage tank are obtained. The cryogenic effect on the structure property of storage tank has been defined.;Part 3: The cryogenic effect of LNG storage tank under the condition of different leakage level, considering reservoir gasification and earthquake action has been analyzed. The structural responses of LNG storage tanks on above three condition are obtained. The failure mechanism of LNG storage tank on leak condition has been preliminary explored.