A pump-free boosting system and its application to liquefied natural gas supply for large ships

•The pump-free FGS (fuel gas supply) system employs two mini-vaporizers to ensure continuous export.•The mini-vaporizers use the partially evaporated BOG (boil-off gas) to pressurized LNG (liquefied natural gas).•The feasibility and economics of the pump-free FGS system were verified.•The pump-free FGS system offers much lower expenditures than pump-based system.

This study proposes a new boosting system that is capable of increasing the pressure of a low-temperature liquid such as LNG (liquefied natural gas) and supplying it continuously to a ship engine without using cryogenic pumps. The system consists of two boosters, each of which is equipped with a mini-vaporizer and regulating valves. The two boosters operate alternately to ensure a continuous supply of the low-temperature pressurized liquid. The operating philosophy is that the mini-vaporizer of the first booster increases the internal pressure and supplies the pressurized liquid to the engine while the other booster is filled with the low-pressure fresh liquid, waiting for its turn to supply the liquid to the engine. This boosting system is applied to an LNG fuel gas supply system. Dynamic process simulation is conducted to demonstrate its operational feasibility. Assessment of operation availability and life-cycle cost analysis are also conducted to show that the proposed system offers better reliability and cost-effectiveness than the conventional pump system.