Patent ID: 9644888
Date: 2017-05-09
CPC Classifications: F01D,F25J

Claim:
1. A liquefier system comprising: a feed line configured to feed a raw material gas from a raw material supply source; a circulation compressor configured to compress a cooling medium; an expansion turbine configured to reduce a temperature of the cooling medium by expansion, the cooling medium having been compressed by the circulation compressor; a heat exchanger configured to cool down the raw material gas that flows through the feed line by means of the cooling medium whose temperature has been reduced by the expansion turbine; a cooling medium circulation line configured to guide the cooling medium from the circulation compressor to the expansion turbine and return the cooling medium from the expansion turbine to the circulation compressor through the heat exchanger; a controller configured to control operations of the expansion turbine and the circulation compressor such that a high-load operation and a low-load operation are performed, the high-load operation being an operation in which a pressure of the cooling medium that flows through a portion of the cooling medium circulation line, the portion extending from the circulation compressor to the expansion turbine, becomes greater than or equal to a predetermined pressure, the low-load operation being an operation in which the pressure of the cooling medium that flows through the portion of the cooling medium circulation line becomes less than the predetermined pressure, the controller driving the circulation compressor and the expansion turbine to rotate regardless of whether the high-load operation or the low-load operation is being performed, such that the cooling medium circulates through the cooling medium circulation line; a static pressure gas bearing configured to rotatably support a rotating shaft of the expansion turbine; and a bearing supply line configured to supply a gas to the static pressure gas bearing through the bearing supply line, wherein the predetermined pressure is a pressure necessary for the static pressure gas bearing to support the rotating shaft, a pressure of the raw material gas in a predetermined portion of the feed line is kept greater than or equal to the predetermined pressure regardless of whether the high-load operation or the low-load operation is being performed, and the bearing supply line connects the predetermined portion of the feed line to a gas inlet of the static pressure gas bearing, such that the raw material gas that flows through the feed line and whose pressure is greater than or equal to the predetermined pressure is supplied to the static pressure gas bearing as the gas.