LIQUEFACTION PROCESS

摘要

A natural gas liquefaction process comprises passing natural gas through a series of heat exchangers (150, 151, 153) in countercurrent relationship with a gaseous refrigerant circulated through work expansion cycle. The work expansion cycle comprises compressing the refrigerant, dividing and cooling the refrigerant to produce at least first and second cooled refrigerant streams (126, 128), substantially isentropically expanding the first refrigerant stream (126) to a coolest refrigerant temperature, substantially isentropically expanding the second refrigerant stream (128) to an intermediate refrigerant temperature warmer than said coolest refrigerant temperature, and delivering the refrigerant in the first and second refrigerant streams (126, 128) to a respective heat exchanger (153, 151) for cooling the natural gas through corresponding temperature ranges. The refrigerant in the first stream (126) is isentropically expanded to a pressure at least 10 times greater than the total pressure drop of the first refrigerant stream across said series of heat exchangers (150, 151, 153), said pressure being in the range of 1.2 to 2.5 MPa.