(138f) LNG Rollover: Converting a Safety Problem to Tank Loading Operational Asset

Rollover following density stratification in LNG storage tanks was considered a problem which required careful monitoring following several unexpected rollover events in the 1970s. However today density stratification is routinely used to reduce high LNG boil-off gas rates, particularly when tank filling through the top loading nozzles is required for heavier LNGs. Thus boil-off gas compressor and pre-heater costs can be reduced both during and after unloading LNG Tankers.

LNG rollover predictive models are widely used tools in conjunction with internal tank travelling temperature and density instrumentation to predict and update the behaviour of LNG stratification. Several proprietary and commercial rollover software models are identified and the potential use of Computational Fluid Dynamics (CFD) models for the non-circular tanks proposed for off-shore applications is described in this paper.