METHOD FOR LIQUEFYING A STREAM RICH IN HYDROCARBONS

摘要

A method for liquefying a stream rich in hydrocarbons, in particular, a natural gas stream is disclosed, wherein the liquefaction of the stream rich in hydrocarbons occurs in a cascade of refrigerant-mixture circuits made up of three refrigerant-mixture circuits, the first refrigerant mixture circuit carrying out the pre-cooling, the second refrigerant mixture circuit carrying out the liquefaction and the third refrigerant mixture circuit carrying out the supercooling of the stream rich in hydrocarbons. According to the invention: a) the refrigerant mixture in each refrigerant mixture circuit is evaporated up to just one pressure, b) the heat exchange for the precooling of the stream rich in hydrocarbons between the stream (1, 1') rich in hydrocarbons and the refrigerant mixture (6) in the precooling circuit is carried out in two or more identical heat exchangers (E1, EV) arranged in parallel, c) the compression of the refrigerant mixture (8, 8') in the precooling circuit is achieved with a double-flow type compressor (V1) and d) the compression of the refrigerant mixture (13, 13') in the liquefying circuit occurs in at least two stages (V2, V2'), the compression in the first stage being achieved by a double-flow type compressor (V2).