Fuel gas supply system and method of an lng carrier

Abstract

A fuel gas supply system of a vessel, such as an LNG carrier, is provided for supplying fuel gas to a high-pressure gas injection engine of an LNG carrier, wherein LNG is extracted from an LNG storage tank of the LNG carrier, compressed at a high pressure, gasified, and then supplied to the high-pressure gas injection engine. In one embodiment, the system includes a boil-off gas reliquefaction apparatus for reliquefying boil-off gas generated in the LNG tank.

1 . A fuel gas supply system of a vessel for supplying fuel gas from an LNG tank, which stores LNG as fuel gas, to a high-pressure gas injection engine, the fuel gas supply system comprising:
 a boil-off gas liquefaction line configured to extract boil-off gas generated in the LNG tank;   a compressor installed in the boil-off gas liquefaction line to compress the boil-off gas;   a reliquefaction apparatus configured to reliquefy the compressed boil-off gas;   a high-pressure pump configured to compress the reliquefied boil-off gas at a high pressure between about 200 to about 300 bar gauge pressure and supply the compressed reliquefied boil-off gas as fuel gas to the high-pressure gas injection engine; and   a vaporizer configured to vaporize the reliquefied boil-off gas compressed by the high-pressure pump.   
     
     
         2 . The fuel gas supply system of a vessel according to  claim 1 , further comprising a fuel gas supply line configured to extract LNG from the LNG tank and supply the extracted LNG as fuel gas to the high-pressure gas injection engine. 
     
     
         3 . The fuel gas supply system of a vessel according to  claim 2 , wherein both the liquefied boil-off gas and the LNG extracted from the LNG tank are compressed by the same high-pressure pump and are supplied to the high-pressure gas injection engine.