Liquefied gas treatment system

Abstract

A liquefied gas treatment system according to an embodiment of the present invention includes a boil-off gas heat exchanger exchanging heat between boil-off gas, pressurized by a boil-off gas compressor and recovered along a boil-off gas supply line branching off upstream of a liquefied gas-consuming unit, and the boil-off gas supplied from a liquefied gas storage tank, wherein the boil-off gas heat exchanger cools the boil-off gas, recovered along the boil-off gas supply line, with the boil-off gas, supplied from the liquefied gas storage tank, or flash gas, supplied through a vapor recovery line.

What is claimed is: 
     
         1 . A liquefied gas treatment system, comprising:
 a boil-off gas supply line connected from a liquefied gas storage tank to a liquefied gas-consuming unit;   a boil-off gas compressor provided on the boil-off gas supply line and pressurizing boil-off gas generated from the liquefied gas storage tank;   a boil-off gas heat exchanger provided upstream of the boil-off gas compressor on the boil-off gas supply line and exchanging heat between the boil-off gas, pressurized by the boil-off gas compressor and recovered along the boil-off gas supply line branching off upstream of the liquefied gas-consuming unit, and the boil-off gas supplied from the liquefied gas storage tank;   a boil-off gas decompressor provided downstream of the boil-off gas heat exchanger on the basis of a flow of the boil-off gas, recovered along the boil-off gas supply line, and decompressing the boil-off gas compressed by the boil-off gas compressor;   a vapor-liquid separator separating flash gas from the boil-off gas decompressed by the boil-off gas decompressor; and   a vapor recovery line connected from the vapor-liquid separator to the boil-off gas heat exchanger and supplying the flash gas to the boil-off gas heat exchanger,   wherein the boil-off gas heat exchanger cools the boil-off gas, recovered along the boil-off gas supply line, with the boil-off gas, supplied from the liquefied gas storage tank, or the flash gas, supplied through the vapor recovery line.   
     
     
         2 . The liquefied gas treatment system of  claim 1 , wherein the boil-off gas, heat-exchanged by the boil-off gas heat exchanger, is supplied to the boil-off gas decompressor or the boil-off gas compressor. 
     
     
         3 . The liquefied gas treatment system of  claim 1 , wherein the flash gas, heat-exchanged by the boil-off gas heat exchanger, is supplied to and combusted in a gas combustion unit combusting fuel. 
     
     
         4 . The liquefied gas treatment system of  claim 1 , further comprising a mixer provided upstream of the boil-off gas heat exchanger on the boil-off gas supply line, mixing the boil-off gas, supplied from the liquefied gas storage tank, with the flash gas, recovered from the vapor-liquid separator, and supplying mixed gases to the boil-off gas heat exchanger,
 wherein the flash gas, heat-exchanged by the boil-off gas heat exchanger, is supplied to the mixer.   
     
     
         5 . The liquefied gas treatment system of  claim 1 , further comprising a liquid recovery line connected from the vapor-liquid separator to the liquefied gas storage tank and recovering the boil-off gas in liquid state, separated by the vapor-liquid separator, to the liquefied gas storage tank. 
     
     
         6 . The liquefied gas treatment system of  claim 1 , wherein the boil-off gas decompressor is a Joule-Thomson valve. 
     
     
         7 . The liquefied gas treatment system of  claim 1 , further comprising a flash gas bypass line branching off from the vapor recovery line and allowing at least part of the flash gas, exhausted from the vapor-liquid separator, to bypass the boil-off gas heat exchanger.