Integrally-geared compressors for precooling in LNG applications

A natural gas liquefaction system is disclosed, which comprises at least a pre-cooling loop (103), through which a first refrigerant is adapted to circulate. The pre-cooling loop comprises at least one compressor (109) for pressurizing the first refrigerant; at least one prime mover (111) for driving the compressor (109); at least one condenser (115) for removing heat from the first refrigerant; at least a first expansion element (119A-119D) for expanding the first refrigerant; at least a first heat exchanger (123A- 123D) for transferring heat from natural gas to the first refrigerant. The system further comprises at least a cooling loop (105), downstream of the pre-cooling loop, where through a second refrigerant circulates. The natural gas is adapted to be sequentially cooled in the pre-cooling loop and in the cooling loop. The compressor of the pre-cooling loop is an integrally-geared turbo-compressor comprising a plurality of compressor stages (109A-109D).