SAFETY ASPECTS OF DIFFERENT COMPOSITION LIQUEFIED NATURAL GAS STORAGE PROCESSES.

Liquefied natural gas (LNG) is transported from the ships by above -ground insulated unloading pipelines and stored in tanks. The cryogenic temperature associated with LNG processing creates safety issues for LNG transfer and storage. Due to heat transfer from ambient air to unloading pipelines and storage tanks a part of the LNG can evaporate resulting in excessive Boil Off Gas (BOG) generation and pressure build up in the storage tank. Boil off gas in the LNG supply chain is one of the most important factors for LNG storage terminal safety or technical and economic assessment of unloading process. Evaporation causes LNG quality and composition changes during storage process. If LNG is stored over an extensive period of time without replenishment the methane content is continuously decreasing and the actual physical parameters of the LNG can change.. This process is known as "weathering" of the LNG. Under unfavourable conditions changes in the composition of LNG may cause roll-over phenomenon and threatening the safety of the storage process. Influence of variability of liquefied natural gas composition on safety of its storage process in different conditions and analysis of basic parameters changes in storage tank are shown in this paper.