Patent ID: 7581411

Claim:
A process for reliquefaction of boiloff gas from a liquefied natural gas storage container, comprising the steps of: compressing a refrigerant in only one single stage main compressor to yield a compressed refrigerant; passing the compressed refrigerant from the only one single stage main compressor through a first aftercooler for cooling to a first temperature; passing the cooled refrigerant from the first aftercooler through a first flow path of a first heat exchanger for further cooling to a second temperature lower than said first temperature; withdrawing a first portion of said refrigerant at said second temperature from the first flow path of said first heat exchanger; passing the first portion of said refrigerant through a first turboexpander for cooling to a third temperature lower than said second temperature; passing the refrigerant from said first turboexpander through a second flow path of the first heat exchanger in a direction countercurrent to the refrigerant flowing through the first flow path of said first heat exchanger; compressing a boiloff gas from a liquefied natural gas storage container through a boiloff compressor to a desired pressure; and passing the compressed boiloff gas from the boiloff compressor through a third flow path of the first heat exchanger in a direction countercurrent to the refrigerant flowing through said second flow path thereof, for cooling to a temperature sufficient to achieve liquefaction thereof.