Gas liquefaction process with partial condensation of mixed refrigerant at intermediate temperatures

A method for providing refrigeration for liquefying a feed gas which comprises:

• (1) providing refrigeration from a first recirculating refrigeration circuit which provides refrigeration in a temperature range between a first temperature and a second temperature which is lower than the first temperature;
• (2) providing refrigeration from a second recirculating refrigeration circuit in a temperature range between the second temperature and a third temperature which is lower than the second temperature, wherein the first refrigeration circuit provides refrigeration to the second refrigeration circuit in the temperature range between the first temperature and the second temperature;
• (3) withdrawing a mixed refrigerant vapor from a main heat exchange zone in the second recirculating refrigeration circuit and compressing the mixed refrigerant vapor to a final highest pressure to yield a compressed mixed refrigerant vapor;
• (4) partially condensing at least a portion of the compressed mixed refrigerant vapor in the second recirculating refrigeration circuit and separating the resulting partially condensed mixed refrigerant into at least one liquid refrigerant stream and at least one vapor refrigerant stream;
• and
• (5) subcooling the at least one liquid refrigerant stream to a temperature lower than the second temperature, reducing the pressure of the resulting subcooled liquid refrigerant stream, and vaporizing the resulting reduced-pressure refrigerant stream to provide at least a portion of the refrigeration for liquefying the feed gas between the second temperature and the third temperature;
• wherein
• the step of partially condensing the compressed mixed refrigerant vapor is effected at a pressure essentially equal to the final highest pressure.