May 31, 2021
To enable their storage and export, natural gas and hydrogen are often cooled to cryogenic temperatures to condense them into a liquid. However, heat inevitably then enters the liquid even in the most well insulated storage tank, causing it to start evaporating. This is termed boil-off, and the production of boil-off gas causes economic loss and can pose safety risks. Boil-off is an even bigger problem for the storage of liquid hydrogen than for LNG because its storage temperature is 90 C lower.
To model the boil-off process, the Future Energy Exports Cooperative Research Centre (FEnEx CRC) has supported the development of a free software tool, BoilFAST. This tool enables users to model boil-off production by selecting from a range of available fluids – including equilibrium hydrogen – and by specifying a tank design with heat flows or insulation details. BoilFAST then allows the user to predict the amount of boil-off generated over a specified time, and its impact on key operational parameters such as storage tank pressure, the levels and compositions of the liquid and gas, and venting rate. The model has been extensively validated against industrial tests and laboratory data for published by NASA and the University of Western Australia for both hydrogen and LNG.