Natural gas liquefaction installation arranged at the surface of an expanse of water, and associated cooling method

A natural gas liquefaction installation, arranged at the surface of a body of water, comprising:

• at least one air-cooled heat exchanger, the at least one air-cooled heat exchanger including a tube bundle configured to receive a flow that is to be cooled, and a fan configured to cause a flow of air to circulate across the tube bundle;
• a water-sprayer;
• a desalinizer including a salt water pickup in the body of water, the desalinizer being coupled upstream to the water-sprayer,
• the water-sprayer including at least one spray nozzle opening onto the tube bundle, the at least one spray nozzle being directed towards tubes of the tube bundle so as to spray liquid demineralized water coming from the desalinizer into contact with the tubes of the tube bundle,
• wherein the at least one air-cooled heat exchanger is arranged in a cooling cycle including a coolant circulating through the tube bundle, a compressor configured to compress the coolant upstream from the tube bundle, a coolant expander arranged downstream from the tube bundle and a main heat exchanger configured to place the coolant in a heat exchange relationship with a process fluid to be cooled,
• wherein the cooling cycle includes an intermediate heat exchanger, inserted between the air-cooled heat exchanger and the expander, the intermediate heat exchanger being supplied by a coolant capable of entering into a heat exchange relationship with a flow of salt water coming from the salt water pickup, by a flow of salt water coming from the salt water pickup and/or by a flow of salt water coming from a salt water pump not passing through the salt water pickup.