NOVELTY - The system has a common circuit portion provided in feeding circuit of energy production equipment and comprising compressors (16a, 16b). The circuit portion is delimited by first and second connecting elements. The second connecting element is connectable with three-ways (62, 63) and valves (162, 163, 262, 263). A downstream portion of a heating circuit comprises a third connecting element connectable to a three-way (69) to connect the downstream portion to a downstream portion of a feeding circuit of a burner (5) to evacuate a part of the gas flow from the heating circuit to the burner.    USE - System for treating and supplying a natural gas i.e. liquefied natural gas, from a storage tank to an energy production equipment e.g. thermal engine, fuel cell, gas turbine and electrical generator, for propulsion of a ship (all claimed).    ADVANTAGE - The downstream portion of the heating circuit comprises the connecting element connectable to the three-way to connect the downstream portion of the heating circuit to the downstream portion of the feeding circuit of the burner to evacuate the part of the gas flow from the heating circuit to the burner, thus enabling effective heating of a liquefied natural gas storage tank. The system exhibits an optimized design to allow utilization of components i.e. compressors, to ensure multiple system features.    DETAILED DESCRIPTION - The energy production equipment is designed as a thermal engine (4), an electrical generator (6), a fuel cell or a gas turbine. The compressors are designed as multi-stage compressors. INDEPENDENT CLAIMS are also included for the following:    (1) a ship    (2) a method for filling a tank of a ship    (3) a fluid transfer system.    DESCRIPTION OF DRAWING(S) - The drawing shows a pneumatic circuit diagram of a system for treating and supplying a natural gas to a ship.    Burner (5)    Compressors (16a, 16b)    Three-ways (62, 63)    Three-way for connecting downstream portion of heating circuit to downstream portion of feeding circuit of burner (69)    Valves (162, 163, 262, 263)