Abstract: In a BOG treatment system, boil-off gas (BOG) discharged from a storage tank is compressed, most of the BOG is used as the fuel of vessel engines, and a remaining part of the BOG is liquefied by cold energy of BOG newly discharged from the storage tank and is returned to the storage tank, thereby efficiently utilizing the BOG. The BOG treatment system for a vessel includes a compressor compressing the BOG discharged from the storage tank; a medium pressure gas engine receiving at least a part of the BOG compressed by the compressor, as fuel; a heat exchanger exchanging heat between the remaining part of the BOG, which is not supplied to the medium pressure gas engine as fuel, and the BOG, which is discharged from the storage tank and is not compressed; and an expander decompressing the remaining part of the BOG cooled by the heat exchanger.

Abstract: A hybrid fuel supply system for an engine of a vessel is provided. The hybrid fuel supply system for the engine of the vessel includes: a compression device configured to compress boil-off gas (BOG) generated from liquefied natural gas (LNG) stored in an LNG cargo tank; a high pressure pump configured to compress LNG supplied from the LNG cargo tank; a vaporizer configured to vaporize the LNG compressed by the high pressure pump; and a dual fuel (DF) engine to which the BOG compressed through the compression device is supplied as fuel. The engine of the vessel uses high pressure gas compressed at 150 to 400 bar as fuel and is driven by at least one of the BOG compressed in the compression device and the LNG compressed in the high pressure pump.

Abstract: In a BOG treatment system, boil-off gas (BOG) discharged from a storage tank is compressed, most of the BOG is used as the fuel of vessel engines, and a remaining part of the BOG is liquefied by cold energy of BOG newly discharged from the storage tank and is returned to the storage tank, thereby efficiently utilizing the BOG. The BOG treatment system for a vessel includes a compressor compressing the BOG discharged from the storage tank; a medium pressure gas engine receiving at least a part of the BOG compressed by the compressor, as fuel; a heat exchanger exchanging heat between the remaining part of the BOG, which is not supplied to the medium pressure gas engine as fuel, and the BOG, which is discharged from the storage tank and is not compressed; and an expander decompressing the remaining part of the BOG cooled by the heat exchanger.

Abstract: Provided is a method for operating a fuel supply system for a marine structure. The fuel supply system includes a BOG compression unit configured to receive and compress BOG generated in a storage tank, a reliquefaction apparatus configured to receive and liquefy the BOG compressed by the BOG compression unit, a high-pressure pump configured to compress the liquefied BOG generated by the reliquefaction apparatus, and a high-pressure gasifier configured to gasify the liquefied BOG compressed by the high-pressure pump. The fuel supply system includes a recondenser installed at an upstream side of the high-pressure pump, and the recondenser recondenses a portion or all of the generated BOG by using liquefied gas supplied from the storage tank. During a ballast voyage process, all of the BOG is supplied to and recondensed by the recondenser, and an operation of the reliquefaction apparatus is interrupted.

Abstract: A hybrid fuel supply system for an engine of a vessel is provided. The hybrid fuel supply system for the engine of the vessel includes: a compression device configured to compress boil-off gas (BOG) generated from liquefied natural gas (LNG) stored in an LNG cargo tank; a high pressure pump configured to compress LNG supplied from the LNG cargo tank; a vaporizer configured to vaporize the LNG compressed by the high pressure pump; and a dual fuel (DF) engine to which the BOG compressed through the compression device is supplied as fuel. The engine of the vessel uses high pressure gas compressed at 150 to 400 bar as fuel and is driven by at least one of the BOG compressed in the compression device and the LNG compressed in the high pressure pump.

Abstract: A liquefied gas treatment system includes: a first stream of boil-off gas, which is generated from the liquefied natural gas in the cargo tank and is discharged from the cargo tank; a second stream of the boil-off gas, which is supplied as fuel to the engine in the first stream; and a third stream of the boil-off gas, which is not supplied to the engine in the first stream. The first stream is compressed in a compressor and is then branched into the second stream and the third stream. The third stream is liquefied by exchanging heat with the first stream in a heat exchanger, so that the boil-off gas is treated without employing a reliquefaction apparatus using a separate refrigerant.

Abstract: Provided is a method for operating a fuel supply system for a marine structure. The fuel supply system includes a BOG compression unit configured to receive and compress BOG generated in a storage tank, a reliquefaction apparatus configured to receive and liquefy the BOG compressed by the BOG compression unit, a high-pressure pump configured to compress the liquefied BOG generated by the reliquefaction apparatus, and a high-pressure gasifier configured to gasify the liquefied BOG compressed by the high-pressure pump. The fuel supply system includes a recondenser installed at an upstream side of the high-pressure pump, and the recondenser recondenses a portion or all of the generated BOG by using liquefied gas supplied from the storage tank. During a ballast voyage process, all of the BOG is supplied to and recondensed by the recondenser, and an operation of the reliquefaction apparatus is interrupted.

Abstract: Provided is a nonflammable mixed refrigerant for use in a reliquefaction apparatus of a fuel supply system that compresses BOG generated in an LNG storage tank to a medium pressure, reliquefies the compressed BOG, compresses the reliquefied BOG to a high pressure, gasifies the compressed requefied BOG, and supplies the gasified BOG to a high-pressure natural gas injection engine. A nonflammable mixed refrigerant for use in a fuel supply system for a high-pressure natural gas injection engine is provided. The nonflammable mixed refrigerant cools the BOG by heat exchange with the BOG in the reliquefaction apparatus. The nonflammable mixed refrigerant comprises a mixture of nonflammable refrigerants with different boiling points, and the boiling point of each of the nonflammable refrigerant ranges between a room temperature and a liquefaction temperature of natural gas.

Abstract: Provided is a fuel supply system for a marine structure using a high-pressure natural gas injection engine. The fuel supply system includes: a boil-off gas (BOG) compression unit configured to receive and compress BOG generated in a storage tank storing a liquefied gas; a reliquefaction apparatus configured to receive and liquefy the BOG compressed by the BOG compression unit; a buffer tank configured to receive the liquefied BOG from the reliquefaction apparatus and separate the reliquefied BOG into a gaseous component and a liquid component; a high-pressure pump configured to receive the liquid component from the buffer tank and compress the liquid component; and a high-pressure gasifier configured to gasify the liquid component compressed by the high-pressure pump and supply the gasified liquid component to the high-pressure natural gas injection engine.

Abstract: Provided is a fuel supply system for a marine structure. The fuel supply system includes a BOG compression unit configured to receive and compress BOG generated in a storage tank, a reliquefaction apparatus configured to receive and liquefy the BOG compressed by the BOG compression unit, a high-pressure pump configured to compress the liquefied BOG generated by the reliquefaction apparatus, and a high-pressure gasifier configured to gasify the liquefied BOG compressed by the high-pressure pump. The fuel supply system includes a recondenser installed at an upstream side of the high-pressure pump and configured to recondense a portion or all of the generated BOG by using liquefied gas received from the storage tank. The BOG compression unit compresses BOG to a pressure of about 12 to 45 bara such that the BOG is liquefied under the compression pressure of the BOG compression unit.

Abstract: Provided is a fuel supply system for a high-pressure natural gas injection engine. The fuel supply system includes: a BOG compression unit configured to receive BOG, which is generated in a storage tank, from the storage tank and compress the received BOG to a pressure of 12 to 45 bara; a reliquefaction apparatus configured to receive and liquefy the BOG compressed by the BOG compression unit; a high-pressure pump configured to compress the BOG liquefied by the reliquefaction apparatus; a high-pressure gasifier configured to gasify the BOG compressed by the high-pressure pump and supply the gasified BOG to the high-pressure natural gas injection engine; and an excess BOG consumption unit configured to consume excess BOG corresponding to a difference between an amount of BOG generated in the storage tank and an amount of BOG required as fuel for the high-pressure natural gas injection engine.

Abstract: Provided is a fuel supply method for a marine structure using a high-pressure natural gas injection engine. BOG stored in a stored in the storage tank is compressed to a pressure of 12 to 45 bara (absolute pressure) and then reliquefied. A reliquefaction apparatus includes a cold box configured to exchange heat between a refrigerant and the BOG, a compression unit configured to compress the refrigerant heated by the cold box, an expansion unit configured to expand the compressed refrigerant to drop the temperature thereof, and a plurality of gas-liquid refrigerant separators configured to separate the refrigerant into a gaseous refrigerant and a liquid refrigerant. A gaseous refrigerant and a liquid refrigerant separated by the gas-liquid refrigerant separator disposed at an upstream side are again mixed and supplied to the gas-liquid refrigerant separator disposed at the most downstream among the plurality of gas-liquid refrigerant separators.