Forbedret fremgangsmåde og anlæg til afkøling og likvefaktion af naturgas

The method involves compressing a coolant mixture in a pre-final stage (1A) through a series of stages of a compression unit (1). The mixture is condensed partially by cooling, and then is separated to produce a vapour fraction and a liquid fraction. The vapour fraction is cooled and partially condensed, and then passed through a final compression stage (1C) to obtain a high-pressure vapour. Part of the high-pressure vapour fraction and liquid fraction is then cooled, expanded and circulated through a first heat exchanger (5). During the vapour fraction's cooling and partial condensation stage, the vapour fraction obtained from the separation of the condensed mixture is cooled by passing it through a second heat exchanger (18) with the coolant. The condensed mixture is separated in a first separator (14). The vapour fraction from it is condensed in the second heat exchanger, and then passed through a second separator (15) to produce a vapour and a liquid fraction. The vapour fraction is sent to the final compression stage, and the liquid fraction to the first heat exchanger.