The butane refrigeration system is based on the use of a propane refrigeration system to cool and condense the butane product vapors. The propane refrigerant system includes two equally sized 1750 HP electric motor driven oil flooded, rotary screw type compressors which have a side port connection to permit operation in an economized refrigerant cycle. The other components are lube oil system, air-cooled condenser, refrigerant receiver, propane sub-cooler, and butane condenser.