For applications using medium pressure 2-stroke propulsion a different option is available, where simply circulating a stream of LNG and subcooling it through a heat exchanger, before returning it to the cargo tank.
Cryostar has developed a closed loop cooling system, utilising magnetic bearing turbomachinery technology with several stages of compression and a single expander, to provide the necessary cold power. The system remains completely independent of the usual cargo handling machinery, thereby allowing full optimisation of fuel gas supply systems, while still providing an efficient means for tank pressure control.
The hermetic machinery and closed loop mean that expensive cooling media are avoided and simple operation across a wide flow range without compromising efficiency is possible. Equipment is supplied fully skidded with a minimum of interfaces for simple installation.