Refrigerant charging system for reliquefaction system for ship

A refrigerant charging system for a reliquefaction system for ships, comprising:

• a reliquefaction system provided to a ship and configured to reliquefy boil-off gas generated in a liquefied gas storage tank by compressing the boil-off gas and subjecting the compressed boil-off gas to heat exchange with refrigerant supplied to a heat exchanger while circulating along a refrigerant circulation line;
• a buffer tank configured to store utility N2 to be supplied to the ship;
• a booster compressor configured to receive the utility N2 from the buffer tank, compress the received utility N2, and supply the compressed utility N2 to the refrigerant circulation line;
• and
• a first load-up line along which the utility N2 is supplied from the buffer tank to the refrigerant circulation line without passing through the booster compressor,
• wherein, upon initial charging in a non-operation state of the reliquefaction system, the refrigerant circulation line is charged with refrigerant by supplying the utility N2 from the buffer tank to the refrigerant circulation line along the first load-up line by a pressure differential between the refrigerant circulation line and the buffer tank, and
• wherein a load of the reliquefaction system is controllable by changing a mass flow rate of the refrigerant along the refrigerant circulation line through replenishment or partial discharge of the refrigerant.