Gas refrigeration method.

摘要

In a method of liquefying a permanent gas, such as nitrogen, refrigeration is provided for the permanent gas by one or more working fluid cycles 81 and 89 in which work expanded working fluid is brought into heat exchange relationship with the permanent gas stream at temperatures above the critical temperature of the permanent gas, and a working fluid cycle 77 in which work expanded working fluid is brought into heat exchange relationship with the permanent gas stream at a temperature below the critical temperature of the permanent gas. The outlet pressure of the turbine 78 is at least 10 atmopsheres and preferably from 12 to 20 atmospheres. By selecting such a high outlet pressure for the turbine 78 and for the turbine of any other working fluid cycle operating at below the critical temperature of the permanent gas, the thermodynamic efficiency of such working fluid cycles may be increased by virtue of the relatively high specific heat that the working fluid has at such pressure.