LNG STIRRING MECHANISM AND COUNTERMEASURES IN LARGE LNG STORAGE TANKS

In those LNG receiving terminal stations under continuous operation, LNG storage tanks will storage LNG without necessary to be emptied. Due to different sources at different times, the filled LNG in the storage tank will be stratified by various temperature and different density and even stirred after some time, which will directly threaten the safety of the storage tank, and meanwhile increase the cost on dealing with the BOG (boiling of gas) by LNG stirring. After thorough analysis on the mechanism and hazards of the LNG stirring, this paper discusses how to prevent LNG in the storage tanks from being stratified and stirred. The basic data of solution was provided when the tank was designed (e.g. loading tubes were designed respectively at the top and bottom of the tank); after the tank put into operation, a reasonable loading solution (e.g. LNG was filled from the ship either through the top or the bottom of the tank) was adopted to make different-density LNG mixed without being so variously stratified that the rate of stirring could be decreased to a large degree.