PROCESS FOR LIQUEFYING 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 subcooled by indirect heat exchange with two refrigerant mixtures circulating in the circuits (I) and (II). A first refrigerant mixture is compressed, cooled and at least partially condensed by heat exchange in C1 with an external fluid. The first refrigerant mixture is then subcooled by heat exchange in C2 before being partially or completely expanded so as to cool the natural gas and a second refrigerant mixture by heat exchange. The second refrigerant mixture is compressed, cooled and at least partially condensed by heat exchange in C3 with an external fluid before being cooled in the first circuit (I) by heat exchange with the first refrigerant mixture so as to be subsequently expanded and to allow the natural gas to be cooled, by heat exchange, until it is liquefied. The first and second refrigerant mixtures comprise at least ethylene.