Liquefaction method and system

A closed loop system for liquefaction utilizing substantially isentropic expansion of a gaseous refrigerant, comprising:

• A refrigerant compressor;
• A first heat exchanger fluidly coupled to the low pressure refrigerant compressor and adapted to receive at least a portion of a compressed gaseous refrigerant stream from the refrigerant compressor;
• A first expander fluidly coupled to the first heat exchanger and adapted to receive at least a portion of the cooled, compressed refrigerant stream from the first heat exchanger;
• A second heat exchanger fluidly coupled to the first expander and adapted to receive at least a portion of an expanded gaseous refrigerant stream from the first expander, wherein the at least a portion of the expanded gaseous refrigerant stream is substantially vapor;
• A first conduit for extracting a first portion of the expanded gaseous refrigerant stream from the second heat exchanger from an intermediate location of the second heat exchanger to balance a precooling section of the second heat exchanger;
• A second conduit for extracting at least a second portion of the expanded gaseous refrigerant stream from the second heat exchanger from the warm end of the second heat exchanger;
• and
• A third conduit for introducing a feed gas stream in the second heat exchanger to form a substantially liquefied feed gas stream through indirect heat exchange against at least a portion of an expanded gaseous refrigerant stream from the first expander.