Turboexpander

A turboexpander, also referred to as a turbo-expander or an expansion turbine, is a centrifugal or axial flow turbine through which a high pressure gas is expanded to produce work that is often used to drive a compressor.

Because work is extracted from the expanding high pressure gas, the expansion is approximated by an isentropic process (i.e., a constant entropy process) and the low pressure exhaust gas from the turbine is at a very low temperature, −150 °C or less depending upon the operating pressure and gas properties. Partial liquefaction of the expanded gas is not uncommon.