| 摘要 |
Natural gas is liquefied using two closed cycle, multicomponent refrigerants in which high level refrigerant cools the low level refrigerant and the low level refrigerant cools and liquefies the natural gas, in an installation which comprises (a) heat exchanger for cooling and liquefying natural gas against low level refrigerant; (b) at least 1 compressor for compressing low level refrigerant to elevated pressure; (c) auxiliary heat exchanger for cooling low level refrigerant against high level refrigerant in multiple stages; (d) phase separator for sepg. low level refrigerant into vapour and liq. phase streams; (e) separate vapour and liq. phase streams are conveyed to heat exchanger of step (a) and recycled to compressor of step (b); (f) at least 1 compressor for compressing high level refrigerant to elevated pressure; (g) aftercooling heat exchanger for cooling compressed high level refrigerant against external cooling fluid; (h) phase separator for sepg. the high level refrigerant into vapour and liq. phase streams; (i) high level vapour phase stream is conveyed through auxiliary heat exchanger of step (c) and expanding the stream to cool low level refrigerant stream; (j) high level liq. phase stream is conveyed through auxiliary heat exchanger of step (c), including sepg. portions of stream and individually expanding them to lower temp. and pressure to cool low level refrigerant; and (k) high level refrigerant is recycled for recompression in step (f). |
