PRESSURE CONTROL DEVICE AND PRESSURE CONTROL METHOD FOR CARGO TANK IN LIQUEFIED NATURAL GAS CARRIER

摘要

PROBLEM TO BE SOLVED: To provide a pressure control device and a pressure control method for a cargo tank reducible in cost while controlling the pressure of the cargo tank within a specified range by safely treating generated boil-off gas(BOG) without the large increase of equipment cost. SOLUTION: This pressure control device for a cargo tank 1 controls the pressure of the cargo tank 1 by supplying the BOG of liquefied natural gas in storage generated in the cargo tank 1, to an incineration system 6 via compressors. In this case, a reliquefying device 5 is disposed in a position downstream of first and second compressors 3, 4 and upstream of the cargo tank 1, and the BOG exhausted from the second compressor 4 is liquefied by the reliquefying device 5 and returned to the cargo tank 1.