Boil-off gas re-condensation device

Abstract

A boil-off gas recondensing device is mountable on a boil-off gas exhaust line for releasing an internal pressure of a cryogenic liquid storage tank. The boil-off gas exhaust line includes an introduction path for introducing a boil-off gas from the cryogenic liquid storage tank to the boil-off gas recondensing device, and an external exhaust path for exhausting the boil-off gas from the boil-off gas recondensing device to an outside. The boil-off gas recondensing device includes a cryostat, and a recondenser that is accommodated in the cryostat and recondenses the boil-off gas. The cryostat includes a boil-off gas inflow path that is connected to the introduction path and allows inflow of the boil-off gas into the recondenser from the introduction path, and a boil-off gas outflow path that is connected to the external exhaust path and allows outflow of the boil-off gas from the recondenser to the external exhaust path.

What is claimed is: 
     
         1 . A boil-off gas recondensing device mountable on a boil-off gas exhaust line for releasing an internal pressure of a cryogenic liquid storage tank, in which the boil-off gas exhaust line includes an introduction path for introducing a boil-off gas from the cryogenic liquid storage tank to the boil-off gas recondensing device, and an external exhaust path for exhausting the boil-off gas from the boil-off gas recondensing device to an outside, the boil-off gas recondensing device comprising:
 a cryostat; and   a recondenser that is accommodated in the cryostat and recondenses the boil-off gas,   wherein the cryostat comprises:
 a boil-off gas inflow path that is connected to the introduction path of the boil-off gas exhaust line and allows inflow of the boil-off gas into the recondenser from the introduction path, and 
 a boil-off gas outflow path that is connected to the external exhaust path of the boil-off gas exhaust line and allows outflow of the boil-off gas from the recondenser to the external exhaust path. 
   
     
     
         2 . The boil-off gas recondensing device according to  claim 1 ,
 wherein a boiling point of the boil-off gas is 10 K or more.   
     
     
         3 . The boil-off gas recondensing device according to  claim 1 , further comprising:
 a cryocooler having a single stage and mounted on the cryostat to cool the recondenser.   
     
     
         4 . The boil-off gas recondensing device according to  claim 3 , further comprising:
 a sensor that measures a pressure or a temperature of the boil-off gas; and   a controller that is configured to control a refrigeration output of the cryocooler based on an output of the sensor.   
     
     
         5 . The boil-off gas recondensing device according to  claim 4 ,
 wherein the controller is configured to compare the output of the sensor with a first threshold value, increase the refrigeration output of the cryocooler in a case where the output of the sensor exceeds the first threshold value, and maintain or decrease the refrigeration output of the cryocooler in a case where the output of the sensor falls below the first threshold value.   
     
     
         6 . The boil-off gas recondensing device according to  claim 5 ,
 wherein the controller is configured to compare the output of the sensor with a second threshold value, which is lower than the first threshold value, operate the cryocooler in a case where the output of the sensor exceeds the second threshold value, and stop the operation of the cryocooler in a case where the output of the sensor falls below the second threshold value.   
     
     
         7 . The boil-off gas recondensing device according to  claim 1 , further comprising:
 a liquid supply path that is connected to the recondenser and allows the boil-off gas recondensed by the recondenser to be resupplied to the cryogenic liquid storage tank.   
     
     
         8 . The boil-off gas recondensing device according to  claim 7 ,
 wherein the liquid supply path merges with a cryogenic liquid supply line to the cryogenic liquid storage tank.