Power-saving liquefied-gas-fuel ship and method for processing boil-off gas for liquefied-gas-fuel ship

A power-saving liquefied-gas-fuel ship comprising:

• a liquefied gas storage tank configured to store liquefied gas;
• an engine configured to use the liquefied gas stored in the liquefied gas storage tank or boil-off gas generated by spontaneous vaporization of the liquefied gas as fuel;
• a fuel feeder configured to supply the liquefied gas as fuel for the engine;
• a compressor configured to compress the boil-off gas to a pressure required for the engine;
• a heat exchanger configured to cool the remaining boil-off gas not supplied to the engine among the boil-off gas compressed by the compressor;
• a refrigerant compressor provided to a refrigerant circulation line and configured to compress refrigerant discharged from the heat exchanger after heat exchange in the heat exchanger;
• the refrigerant circulation line configured to supply the refrigerant to the heat exchanger to cool the refrigerant compressed by the refrigerant compressor by heat exchange with uncompressed boil-off gas introduced from the liquefied gas storage tank to the compressor;
• a cold heat recovery device configured to recover cold heat of the liquefied gas supplied as fuel for the engine to cool the refrigerant compressed by the refrigerant compressor;
• a refrigerant cooling line branched from the refrigerant circulation line connected from the refrigerant compressor to the heat exchanger, configured such that part or all of the refrigerant compressed by the refrigerant compressor is supplied to the cold heat recovery device and cooled by heat exchange with the liquefied gas;
• and
• a flow rate regulator configured to control a flow rate branched to the refrigerant cooling line and a flow rate branched to the refrigerant circulation line among the refrigerant compressed by the refrigerant compressor.