Gas supply arrangement of a marine vessel and method of controlling gas pressure in a gas supply arrangement of a marine vessel

Abstract

A gas supply arrangement of a marine vessel being adapted to carry liquefied gas in its cargo tank having an ullage space section and a liquid phase section, and to utilize the cargo as fuel to provide power for the vessel, the arrangement comprising a first gas supply line which connects an ullage space section of the cargo tank and a gas main supply line and which is provided with a compressor for raising the pressure of the gas to an adequate level, a second gas supply line which connects liquid phase section of the cargo tank and the gas main supply line and which is provided with at least a pump for raising the pressure of the liquid gas and for pumping it forward. The second gas supply line is provided with a gas reservoir having an ullage space section and liquid phase section, which reservoir is connected to the liquid phase section of the cargo tank by a first duct section of the second gas supply line and to the gas main supply line by a second duct section of the second gas supply line. The invention relates also to corresponding method.

1 - 12 . (canceled)  
   
   
       13 . Gas supply arrangement of a marine vessel being adapted to carry liquefied gas in its cargo tank having an ullage space section and a liquid phase section, and to utilize the cargo as fuel to provide power for the vessel, the arrangement comprising: 
 a first gas supply line, which connects an ullage space section of the cargo tank and a gas main supply line and which is provided with a compressor for raising the pressure of the gas to an adequate level,    a second gas supply line which connects liquid phase section of the cargo tank and the gas main supply line and which is provided with at least a pump for raising the pressure of the liquid gas and for pumping it forward, wherein the second gas supply line is provided with a gas reservoir having an ullage space section and liquid phase section, which reservoir is connected to the liquid phase section of the cargo tank by a first duct section of the second gas supply line and to the gas main supply line by a second duct section of the second gas supply line.    
   
   
       14 . Gas supply arrangement according to  claim 13 , wherein the reservoir is provided with temperature control unit.  
   
   
       15 . Gas supply arrangement according to  claim 14 , wherein the temperature control unit of the reservoir comprises adjustable heating device for heating the liquid phase gas in the reservoir.  
   
   
       16 . Gas supply arrangement according to  claim 13 , wherein the reservoir is provided with surface level control arrangement for controlling the surface level of the liquid phase section.  
   
   
       17 . Gas supply arrangement according to  claim 14 , wherein the heating device is provided with control device responsive to the gas pressure in the reservoir.  
   
   
       18 . Gas supply arrangement according to  claim 17 , wherein the heating device is provided with a heat exchanger external to the reservoir being in connection with the liquid phase section of the reservoir by piping.  
   
   
       19 . Gas supply arrangement according to  claim 13 , wherein the reservoir is dimensioned to have a volume corresponding to few hours gas consumption through the gas main supply line.  
   
   
       20 . Gas supply arrangement according to  claim 13 , wherein the first duct section of the second gas supply line extends into a liquid phase section of the reservoir, and that the second duct section of the second gas supply line extends from the ullage space section of the reservoir to the gas main supply line.  
   
   
       21 . Gas supply arrangement according to  claim 13 , wherein the second duct section of the second gas supply lines provided with an automatically controlled closing valve.  
   
   
       22 . Gas supply arrangement according to  claim 13 , wherein the liquid phase section of the reservoir and the cargo tank are connected with each other with a return line provided with a valve.  
   
   
       23 . Method of controlling gas pressure in a gas supply arrangement of a marine vessel with liquefied gas cargo tank having an ullage space section and liquid phase section, and a gas consumption device, in which gas from the cargo tank is led to the consumption device via a first gas supply line which is provided with a compressor, the compressor raising the pressure of the boil-off gas to an adequate level, and additionally or alternatively via a second gas supply line, which connects liquid phase section of the cargo tank and the gas the gas consumption device, the second gas supply line being provided with a pump for raising the pressure of the liquid gas and pumping it forward, wherein in the second gas supply line gas is fed into a reservoir having an ullage space section and liquid phase section, in which reservoir the gas is temporarily stored and from which gas is introduced to the gas consumption device.  
   
   
       24 . Method of controlling gas pressure according to  claim 23 , wherein the pressure of the gas in the in the second gas supply line is controlled by controlling the temperature of the liquid phase section of the reservoir.