Abstract: A charge gas compression train for ethylene, including on the same shaft line a steam turbine and a first compressor including a first group of compression stages, a second group of compression stages and a third group of compression stages, the first group of compression stages including an outlet configured to be connected to a first intercooler inlet, the second group of compression stages including a second compressor inlet configured to be connected to a first intercooler outlet, the second group of compression stages including a second compressor outlet configured to be connected to a second intercooler inlet, the third group of compression stages including a third compressor inlet configured to be connected to a second intercooler outlet; the first, the second and the third group of compression stages being integrated in a first common casing and operating at the same rotation speed of the steam turbine; the first compressor including a plurality of unshrouded and shrouded impellers, wherein at least a