Gas supply arrangement of a marine vessel and method of providing gas in a gas supply arrangement of a marine vessel

A method of supplying gas to a gas consumption device of a marine vessel with a cargo tank for liquefied gas, the cargo tank having an ullage space section and liquid phase section and also having gas main supply line leading to the gas consumption device, said method comprising:

• supplying gas from the ullage space section of the cargo tank to the gas main supply line via a first gas supply line which is provided with a compressor for raising the pressure of gas supplied via the first gas supply line to an adequate level,
• supplying gas to the gas main supply line via a second gas supply line which connects the liquid phase section of the cargo tank to the gas main supply line,
• raising the pressure of liquid gas in the second gas supply line and pumping the liquid gas forward in the second gas supply line to a gas reservoir having an ullage space section and a liquid phase section,
• temporarily storing gas in the gas reservoir, and
• supplying gas from the ullage space section of the gas reservoir to the gas main supply line.

A marine vessel adapted to carry liquefied gas in a cargo tank having an ullage space section and a liquid phase section, the vessel comprising:

• a gas consumption device for utilizing gas from the cargo tank as fuel to provide power for the vessel,
• a first gas supply line connecting the ullage space section of the cargo tank to the gas consumption device,
• a compressor for raising the pressure of gas supplied through the first gas supply line to an adequate level for supply to the gas consumption device,
• a second gas supply line connecting the liquid phase section of the cargo tank to the gas consumption device, and
• pump for raising the pressure of liquid gas in the second gas supply line and pumping the liquid gas toward the gas consumption device,
• wherein the second gas supply line includes a gas reservoir having an ullage space section and a liquid phase section, a first duct connecting the liquid phase section of the cargo tank to the gas reservoir, and a second duct connecting the ullage space section of the gas reservoir to the gas consumption device.