Gas refrigeration method and apparatus

Abstract From the Canadian patent

There is disclosed a method of liquefying a permanent gas stream, comprising the steps of reducing the temperature of the permanent gas stream at elevated pressure to below its critical temperature, and performing at least two working fluid cycles to provide at least part of the refrigeration necessary to reduce the temperature of the permanent gas to below its critical temperature, each such working fluid cycle comprising compressing the working fluid cooling, it, work expanding the cooled working fluid warming the, work expanded working fluid in countercurrent heat exchange with the permanent gas stream and with the working fluid being cooled, refrigeration thereby being provided for the …