METHOD FOR LIQUEFACTING A NATURAL GAS WITH REFRIGERANT MIXTURES CONTAINING AT LEAST ONE UNSATURATED HYDROCARBON

摘要

The invention relates to a process for liquefying natural gas in which the natural gas is cooled, condensed and cooled by indirect heat exchange with two refrigerant mixtures circulating in the circuits (I) and (II). A first refrigerant mixture is compressed, cooled and condensed at least partially by heat exchange in C1 with an external fluid. The first refrigerant mixture is then subcooled by heat exchange in C2, expanded then partially or completely to heat-exchange the natural gas and a second refrigerant mixture. The second refrigerant mixture is compressed, cooled and at least partially condensed by exchanging heat in C3 with an external fluid, and then cooled in the first circuit (I) by heat exchange with the first refrigerant mixture to then be expanded and allow cooling natural gas, by heat exchange, until its liquefaction. The first and / or second refrigerant mixture comprises at least one unsaturated hydrocarbon.