Oil and Gas Division > Case Studies > GTT (FRANCE)

Safe evaporation procedure for LNG container system in accident scenario

TransAT


TransAT
TransAT
TransAT

Overview: GTT designs insulated container systems for maritime transport of Liquefied Natural Gas (LNG). The tanks are about 40m across, filled with a liquid at -110°C, and insulated by a layered arrangement of wooden structures, perlite, glass wool, and invar membranes.

The challenge: In case of an LNG leak into the first insulating layer, an emergency procedure exists to empty the tank and dry up the flooded spaces. This procedure involves blowing a hot inert gas into the tank to evaporate the liquid. If evaporation takes place too quickly, confinement effects can lead to pressure build-up and structural damage. The challenge is to devise a safe heating procedure that preserves the insulating membrane integrity and complies with harbors’ regulations.

TransAT Solution: A multi-scale approach was used to simulate the response of the whole insulating layer to different heating scenarios. Some components of the system were initially partly flooded with LNG. Phase-change and heat transfer models at the smaller scales were coupled with larger scale heat and mass transport fluxes. Most of the evaporating gas was constrained through narrow gaps and permeable porous media. The pressure drop in those sections had to be resolved accurately as it turned out to be a decisive factor to predict the behavior of the full system. The results obtained with TransAT for these cryogenic simulations compared well with the available experimental data and could be used to formulate a safe evaporation procedure in case of emergency.

InfoExpert: Contact our expert

Dr Mathieu Labois
ASCOMP Switzerland
Tel. + 41-44-445-4072
Labois@ascomp.ch