CPC F25B 9/06 (2013.01) [F25J 1/001 (2013.01); F25J 1/005 (2013.01); F25J 1/0007 (2013.01); F25J 1/0052 (2013.01); F25J 1/0065 (2013.01); F25J 1/0067 (2013.01); F25J 1/0204 (2013.01); F25J 1/0221 (2013.01); F25J 1/0244 (2013.01); F25J 2210/42 (2013.01); F25J 2215/32 (2013.01); F25J 2270/16 (2013.01)] | 10 Claims |
1. A raw material gas liquefying device comprising:
a feed line which feeds a raw material gas whose boiling temperature is lower than a boiling temperature of nitrogen;
a refrigerant circulation line which circulates a refrigerant for cooling the raw material gas, the refrigerant circulation line including an expansion unit of a turbine type which expands the refrigerant to generate cryogenic energy, and an expansion unit entrance valve provided at an entrance side of the expansion unit;
a heat exchanger which exchanges heat between the raw material gas and the refrigerant;
a cooler which performs initial cooling of the raw material gas and the refrigerant by heat exchange with liquid nitrogen;
an expansion unit rotation speed sensor which detects a rotation speed of the expansion unit; and
a controller configured to manipulate an opening rate of the expansion unit entrance valve, wherein:
before start-up of the expansion unit, the opening rate of the expansion unit entrance valve is manipulated so that the expansion unit entrance valve opened and a flow rate of the refrigerant flowing into the expansion unit is reaching a predetermined initial cooling flow rate, a flow of the refrigerant with the predetermined initial cooling flow rate through the expansion unit does not rotate the expansion unit, and
at the start-up and stop of the expansion unit, the opening rate of the expansion unit entrance valve is manipulated, by performing a feedback control, so that the rotation speed of the expansion unit reaches a predetermined target value.
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