| 摘要 |
In this method, the LNG stream ( 11 ) is cooled using a refrigerating fluid ( 83 ) in a first heat-exchanger ( 19 ). The refrigerating fluid ( 83 ) is subjected to a second semi-open refrigeration cycle ( 21 ) which is independent of the first cycle ( 15 ). The method comprises a step for introducing the stream ( 59 ) of sub-cooled LNG into a distillation column ( 49 ) and a step for recovering a stream ( 69 ) of gas at the top of the column ( 49 ). The second refrigeration cycle ( 21 ) comprises a step for forming a stream ( 73 ) of refrigerating fluid from a portion of the top stream ( 69 ) of gas, a step for compressing the stream of refrigerating fluid ( 73 ) to a high pressure, then a step for expanding a portion ( 81 ) of the stream ( 75 ) of compressed refrigerating fluid in order to form a substantially liquid sub-cooling stream ( 83 ). The substantially liquid stream ( 83 ) is evaporated in the first heat-exchanger ( 19 ).
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