LNG process : is the compressor the only requirement for expansion from HIGH PRESSURE to medium pressure and finally to low pressure ? ( propane loop )

The refrigeration loop basically contains the following main components (assumed:2-stages refrigeration loop, propane as refrigerant):

- compressor(s) to boost the gaseous refrigerant from low to intermediate pressure stage and from there to high pressure stage.

- heat exchanger as condenser for the refrigerant to put the heat from the heat source and the compression to a heat sink (i. e. cooling water, sea water, glycol circuit).

- liquid refrigerant receiver.

- expansion devices.

- heat exchangers to get the heat out of the heat source by refrigerant evaporation (i.e. propane chillers for LNG treatment).

This is a very rough description and it hopefully fits the requirements for this question right here. Multi-stage refrigeration plants can have several designs. Providing more details can fill pages.