LNG spill and LNG Rapid-Phase Transition
If LNG escapes from storage or from the transfer system then its cryogenic liquefied state is exposed to the ambient temperature of the environment. In an offshore environment, there is a distinct probability that a spill of LNG could have contact with water. The fast increase in temperature of the LNG causes a rapid transformation from the liquid phase to vapour. This process is known as Rapid-Phase Transition (RPT). By definition, this process will include the pressurized LNG passing its boiling point and rapidly expanding; this is known as boiling liquid expanding vapour explosion (BLEVE).
LNG RPT marine spill
The RPT “cold explosion” phenomenon for LNG on water has been observed in a number of situations and has been studied extensively in both laboratory and large scale tests.
The temperature of the water and the actual composition of the LNG are important factors in determining whether RPT will take place. RPT has also been obtained for pure liquefied propane with a water temperature in the range of 55C (130F).
The purpose of KLAW LNG Emergency Shut-down systems is to eliminate any volume spillage. The specific features of the KLAW LNG safety system will depend on client specification but the ERC will include double closure of the line and instant or controlled shut-off of flow. The KLAW LNG Emergency System provides additional control through the HPU system.