Cooling circuits for gas-fed cooling systems

Abstract

The invention relates to a cooling circuit for a gas-fed cooling system in a floating structure with a tank, the cooling circuit comprising a main loop through which a coolant flows, the main loop comprising: a compression device, a heat exchanger, an internal heat exchanger, and a turbo compressor (13), the cooling circuit comprising a regulating branch connected to the main loop, the regulating branch comprising a valve configured to control the flow of coolant in the regulating branch, the main loop comprising a pressure sensor, the valve controlling the amount of coolant present in the main loop based on the pressure measured by the pressure sensor.

Description

[Technical field]

[0001] The present invention relates to the field of gas-supplied cooling systems in tanks of floating structures, and more particularly to cooling circuits integrated within such gas-supplied cooling systems. [Background technology]

[0002] During the course of a floating structure containing gas in liquid gas tanks intended for delivery to a destination, said floating structure may use at least a portion of the gas in liquid state to supply at least one of its engines via a gas supply system, while in parallel it is necessary to maintain the pressure inside the tanks at an acceptable level, in particular by maintaining the gas cargo in liquid state at an appropriate temperature.

[0003] For this purpose it is known to use a supply circuit which makes it possible to suck in the evaporating gas, recompress it and supply it to the engine or engines. In parallel or as an alternative, a cooling circuit through which a refrigerant fluid flows can reduce the pressure in the tank and re-liquefy part of the gas evaporated in the tank.

[0004] In order to optimally manage the tank pressure by cooling the gas contained in the tank, a certain amount of refrigerant fluid must flow through the cooling circuit. As the refrigerant fluid flows through the various compression and expansion modules, said fluid may leak from seals and bearings of the modules. This causes the amount of refrigerant fluid flowing through the cooling circuit to decrease over time, so that the amount of refrigerant fluid is no longer sufficient to effectively cool the gas contained in the tank. On the other hand, if too much refrigerant fluid flows through the cooling circuit, the pressure in the circuit increases, compromising its proper operation. Summary of the Invention

[0005] The present invention relates to a cooling circuit for a gas supply cooling system from a floating structure, comprising at least one tank adapted to contain a gas in liquid state, said cooling circuit being circulated by a refrigerant fluid intended to reduce the temperature of said gas in liquid state contained in said tank, said cooling circuit comprising a main loop, said main loop comprising: at least one compression device providing compression of said refrigerant fluid; at least one heat exchanger configured for heat exchange between said refrigerant fluid and said gas contained in said tank; at least one internal heat exchanger comprising a first flow path through which the refrigerant fluid flows at a first pressure and a second flow path through which the refrigerant fluid flows at a second pressure lower than the first pressure, the first flow path being arranged downstream of the compression device and upstream of the heat exchanger, and the second flow path being arranged downstream of the heat exchanger and upstream of the compression device; at least one turbocompressor provided with a compression element arranged between the compression device and the first flow passage of the internal heat exchanger, and a turbine arranged between the first flow passage of the internal heat exchanger and the heat exchanger, the compression element and the turbine being rotationally connected by a shaft; Equipped with the cooling circuit includes a metering branch connected to the main loop; the regulating branch comprising at least one valve configured to control flow of refrigerant fluid through the regulating branch; the main loop includes at least one pressure sensor; By providing a cooling circuit characterized in that the valve controls the amount of refrigerant fluid present in the main loop based on the pressure measured by the pressure sensor, it is possible to adjust the amount of refrigerant fluid present in the cooling circuit.

[0006] The amount of refrigerant fluid is always controlled in the main loop by the regulating branch. The cooling circuit according to the invention allows refrigerant fluid to be added to the main loop if the initial amount is not sufficient to perform effective cooling, or allows refrigerant fluid to be removed if there is an excessive amount of refrigerant fluid in the main loop. The amount of refrigerant fluid is determined in real time by pressure measurement in the main loop by a pressure sensor.

[0007] The compressor of the cooling circuit serves to circulate the refrigerant fluid in the main loop, compressing the refrigerant fluid and thus increasing its temperature, which remains permanently in a gaseous state during the circulating process to avoid damaging the compressor or turbo compressor.

[0008] The compression member and the turbine rotate together due to their mechanical connection. Rotation of the turbine rotates the shaft, which in turn rotates the compression member. Thus, the refrigerant fluid is first compressed by the compression member. It then flows through a first passage of the internal heat exchanger and is then expanded by passing through the turbine. The rotation of the turbo compressor is initiated by a drive member, which may directly rotate the turbine as mentioned above, but which may also directly rotate the compression member.

[0009] It should be noted that the shaft only connects the turbine to the compression member of the turbocompressor. The compression device is separate from the turbocompressor and is not connected to the shaft in any manner. In other words, the compression device has its own drive members and the drive members are independent of each other. This arrangement allows the compression device and the turbocompressor to have independent speeds. Thus, the flow rate of the compressed fluid through the compression device can be adjusted independently of the pressure exerted by the compression members.

[0010] The refrigerant fluid becomes low pressure and low temperature at the outlet of the turbine during expansion and passes through an internal heat exchanger. Gas from the tank also flows through the heat exchanger. The latter is at a higher temperature than the refrigerant fluid, so the gas from the tank is cooled by the refrigerant fluid. Thus, the heat exchanger is used, for example, to reduce the temperature of the liquid gas in the tank to prevent overpressure in the tank.

[0011] At the outlet of the heat exchanger, the refrigerant fluid flows through a second flow path of an internal heat exchanger, which exchanges heat between the refrigerant fluid at a first pressure in the first flow path and the refrigerant fluid at a second pressure flowing through the second flow path. In this way, the heat exchange is internal to the main loop and thermodynamic equilibrium in the main loop may be managed.

[0012] The regulation branch has an end connected to the main loop, thereby ensuring a fluid connection with the main loop. The regulation branch may extend, for example, to a refrigerant fluid tank and / or to an outlet to the atmosphere. When it is necessary to increase or decrease the amount of refrigerant fluid in the main loop, the valve opens to allow refrigerant fluid to flow from the refrigerant fluid tank to the main loop or from the main loop to the atmosphere. When the amount of refrigerant fluid in the main loop is acceptable to meet the need to cool the gas contained in the tank, the valve is in a closed position.

[0013] Preferably, the pressure sensor is configured to measure the pressure of the refrigerant fluid in the main loop in order to estimate the amount of refrigerant fluid, where a pressure that is too high indicates that there is too much refrigerant fluid in the main loop, whereas a pressure that is too low indicates that there is too little refrigerant fluid in the main loop.

[0014] According to a feature of the invention, the valve is configured to allow refrigerant fluid to exit the main loop via the regulating branch if the pressure measured by the pressure sensor is greater than a first pressure threshold, the first pressure threshold corresponding to a maximum pressure value above which the cooling circuit does not function optimally. When the first pressure threshold is exceeded, the valve opens and a predetermined amount of refrigerant fluid outside the main loop is allowed to flow via the regulating branch to the atmosphere or to a refrigerant fluid tank for storage therein. The opening of the valve can be, for example, the result of receiving a signal emitted by a pressure sensor after exceeding the first pressure threshold.

[0015] When the measured pressure of the refrigerant fluid falls again below the first pressure threshold, the refrigerant fluid circuit is again functioning optimally, and the valve is closed to prevent more refrigerant fluid from exiting the main loop.

[0016] According to a feature of the invention, the valve is configured to allow refrigerant fluid to enter the main loop via the regulating branch when the pressure measured by the pressure sensor is below a second pressure threshold, lower than the first pressure threshold. The second pressure threshold corresponds to a minimum pressure below which the cooling circuit no longer functions optimally. A pressure that is too low indicates that there is not enough refrigerant fluid to meet the need to cool the gas contained in the tank. Such a shortage of refrigerant fluid can be the result of, for example, refrigerant fluid leaking through a seal of a compression device, a turbo compressor or a turbine. The pressure sensor can then send a signal to the valve of the regulating branch, which can open and add a predetermined amount of refrigerant fluid into the main loop. Thus, the refrigerant fluid stored in the refrigerant fluid tank flows through the regulating branch and reaches the main loop.

[0017] When the pressure measured for the refrigerant fluid again exceeds the second pressure threshold, the refrigerant fluid circuit is again functioning optimally, and the valve is closed to prevent more refrigerant fluid from entering the main loop.

[0018] According to a feature of the invention, the regulation branch is connected to the main loop downstream of the compression device and upstream of the compression member of the turbocompressor, and the pressure sensor is configured to measure the pressure in the main loop between the compression device and the compression member of the turbocompressor, preferably in the same section of the main loop as the fluid connection between the main loop and the regulation branch.

[0019] In the section between the compressor and the compression member, the fluid flows at high pressure, facilitating the flow of refrigerant fluid out of the main loop, although the flow of refrigerant fluid in is also possible.

[0020] According to a feature of the invention, the regulating branch is connected to the main loop downstream of the second flow passage of the internal heat exchanger and upstream of the compressor, and the pressure sensor is configured to measure the pressure in the main loop between the second flow passage of the internal heat exchanger and the compressor. In the section between the second flow passage of the internal heat exchanger and the compressor, the refrigerant fluid flows at low pressure, since this section is located downstream of the turbo compressor and upstream of the compressor. The low pressure flow of the refrigerant fluid is advantageous for more refrigerant fluid to enter the main loop, but also allows for the refrigerant fluid to exit therefrom.

[0021] According to a feature of the invention, the regulation branch is a first regulation branch connected to the main loop downstream of the compression device and upstream of the compression member of the turbo compressor, and the cooling circuit comprises a second regulation branch connected to the main loop downstream of the second flow passage of the internal heat exchanger and upstream of the compression device, the main loop comprising two pressure sensors, a first pressure sensor of which is configured to measure the pressure in the main loop between the compression device and the compression member of the turbo compressor, and a second pressure sensor of which is configured to measure the pressure in the main loop between the second flow passage of the internal heat exchanger and the compression device.

[0022] In other words, two different sections of the main loop of the cooling circuit each comprise a regulation branch. Thus, the cooling circuit may be configured with a regulation branch dedicated to the inflow of refrigerant fluid and a regulation branch dedicated to the outflow of refrigerant fluid. Each of the two regulation branches controls the inflow and outflow of refrigerant fluid into and out of the main loop, respectively. The cooling circuit may also comprise two pressure sensors. Each pressure sensor is configured to measure the pressure of the refrigerant fluid in the section of the main loop to which it connects.

[0023] According to a feature of the invention, the first regulating branch controls the flow of the refrigerant fluid out of the main loop and the second regulating branch controls the flow of the refrigerant fluid into the main loop. The first regulating branch is disposed in a second low pressure section of the main loop. From the viewpoint of pressure difference, it is easier to control the flow of the refrigerant fluid in the high pressure section of the main loop and the flow of the refrigerant fluid into the low pressure section of the main loop.

[0024] According to a feature of the invention, the first regulating branch controls the inflow of the refrigerant fluid into the main loop and the second regulating branch controls the outflow of the refrigerant fluid from the main loop. In practice, the inflow and outflow of the refrigerant fluid can be reversed independently of the pressure difference if the need is felt for reasons such as the layout of the refrigerant fluid tank and / or the outlet to atmosphere.

[0025] According to a feature of the invention, the cooling circuit comprises an additional exchanger arranged between the compression member of the turbo compressor and the first flow path of the internal heat exchanger, the additional exchanger being configured to cool the refrigerant fluid. The cooling of the refrigerant fluid provides a better expansion thereof by the turbine, thus improving the cooling performance of the gas contained in the tank. Since the cooling fluid before passing through the additional exchanger is at high pressure and temperature, the cooling of the refrigerant fluid in the additional exchanger can be done with a third fluid, such as seawater.

[0026] According to a feature of the invention, said refrigerant fluid is nitrogen. Nitrogen is commonly used as a cooling fluid and is compatible with the cooling circuit according to the invention. Moreover, nitrogen is a fluid that is readily available if the floating structure is a ship equipped with a nitrogen generator. It is easier and less costly to establish the connection between the nitrogen generator and the regulating branch or branches of the cooling circuit.

[0027] The present invention also relates to a gas supply and cooling system for a floating structure, comprising at least one tank configured to contain gas in a liquefied state and a supply circuit through which gas from said tank is intended to flow and configured to supply said gas to at least one gas consuming device equipped with said floating structure, characterized in that said gas supply and cooling system comprises the above-mentioned cooling circuit.

[0028] During the transportation of a liquid gas cargo, part of the gas in the tank may vaporize naturally or to supply a gas consumer. To reduce the internal pressure of the tank, the gas in the vapor state may be discharged via the supply circuit or indirectly recondensed via the cooling circuit as described above. A gas consumer connected to the tank by the supply circuit may for example be an engine providing the propulsion of the floating structure or a generator providing electricity to the floating structure.

[0029] Other characteristics and advantages of the invention will become apparent from the following description on the one hand and from a number of example embodiments described, by way of non-limiting indication, with reference to the attached schematic drawings, in which: [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 shows a cooling circuit according to the invention, which comprises a regulation branch for the refrigerant fluid flowing through it. [Diagram 2] FIG. 2 shows a cooling circuit according to the invention with two regulation branches. [Diagram 3]FIG. 3 shows a first embodiment of a gas supply cooling system comprising a cooling circuit. [Figure 4] FIG. 4 shows a second embodiment of a gas supply cooling system comprising a cooling circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Figure 1 shows a cooling circuit 4 that can be incorporated into a gas supply cooling system of a floating structure, which transports and / or stores gas in liquid state and is equipped with a tank containing said gas, which is not shown.

[0032] The cooling circuit 4 comprises a main loop 22 through which a refrigerant fluid, for example nitrogen, flows. The main loop 22 comprises a compression device 10, a turbo compressor 13, an internal heat exchanger 18, a heat exchanger 17 and an additional exchanger 38. The purpose of the cooling circuit 4 is to make the refrigerant fluid flow in the main loop 22 in such a way that it passes through the heat exchanger 17 at a low temperature. Gas in liquid state also flows through the heat exchanger 17 in a circuit 8 of gas in liquid state (liquid gas circuit 8), which is partially shown in FIG. 1. As will be explained in more detail later, the liquid gas circuit 8 allows gas in liquid state to flow from the tank towards the heat exchanger 17. After flowing through said heat exchanger 17, the gas in liquid state then returns to the tank. In this way, the refrigerant fluid cools the gas from the tank in the heat exchanger 17. The gas in liquid state pumped to the tank is therefore further cooled by the refrigerant fluid in the heat exchanger 17 and then sent to the tank. The purpose is to lower the average temperature of the tank, thereby condensing evaporated gases and managing the internal pressure of the tank.

[0033] The purpose of the compression device 10 is to pass a refrigerant fluid through it and compress it to a high pressure and temperature. The fluid then passes to a turbo compressor 13. The turbo compressor 13 comprises a compression member 14 and a turbine 15 which are mechanically coupled to each other via a shaft 16. The shaft only connects the compression member 14 to the turbine 15, the compression member 10 itself is not connected to the shaft 16. This arrangement allows the compression device 10 and the compression member 14 to rotate at different rotational speeds.

[0034] The compression member 14 is arranged upstream of the first flow path 23 of the internal heat exchanger 18, while the turbine 15 is arranged downstream of the first flow path 23 of the heat exchanger 18. According to the example shown in Fig. 1, the turbine 15 is rotated by a rotating member, thereby driving the shaft 16, which in turn drives the compression member 14. According to another example, a driving member can drive the compression member 14, which in turn drives the shaft 16, which in turn drives the turbine 15. An additional exchanger 38 is interposed between the compression member 14 and the first flow path 23 of the internal heat exchanger 18.

[0035] Thus, the refrigerant fluid is first compressed in the compression member 14 and then flows through the further exchanger 38 where it is cooled by a third fluid, for example seawater. Cooling via the further exchanger 38 may effectively allow for subsequent expansion through the turbine 15. The refrigerant fluid then flows through the first flow path 23 of the internal heat exchanger 18 and is then expanded in the turbine 15. The expansion reduces the temperature of the refrigerant fluid flowing through the heat exchanger 17, thereby cooling the liquid gas from the tank, as described above.

[0036] At the outlet of the heat exchanger 17, the refrigerant fluid flows through the second flow path 24 of the internal heat exchanger 18. In this way, heat exchange takes place between the refrigerant fluid flowing through the first flow path 23 of the internal heat exchanger 18 at a first pressure and the refrigerant fluid flowing through the second flow path 24 of the internal heat exchanger 18 at a second pressure lower than the first pressure, and the temperature of the refrigerant fluid flowing through the cooling circuit 4 is adjusted.

[0037] During operation of the cooling circuit, it may happen that there is too much or too little refrigerant fluid flowing through the main loop 22. In such cases, the functioning of the cooling circuit 3 and / or its cooling performance may be impaired. Monitoring of the amount of refrigerant fluid in the main loop 22 is provided by a pressure sensor 27 arranged in the main loop 22, which measures the pressure of the refrigerant fluid in real time. The measured pressure is an indication of the amount of refrigerant fluid present in the main loop 22. Too high a pressure relates to an excess of refrigerant fluid, too low a pressure relates to too little amount of refrigerant fluid.

[0038] Furthermore, to regulate the amount of refrigerant fluid in the main loop 22, the cooling circuit 4 comprises a regulating branch 25 connected to the main loop 22. The regulating branch 25 comprises a valve 26 and extends to a refrigerant fluid tank 28 and, if necessary, to an outlet 29 to the atmosphere. If the amount of refrigerant fluid is not compatible with optimal cooling performance, the valve 26 can be opened to allow refrigerant fluid to flow through the regulating branch 25, thereby increasing or decreasing the amount of refrigerant fluid in the main loop 22.

[0039] If there is an excess of refrigerant fluid in the main loop 22, the valve 26 opens, allowing a predetermined amount of refrigerant fluid to exit the main loop 22 through a regulating branch 25 to a refrigerant fluid tank 28 or to an outlet 29 to the atmosphere.

[0040] If too little refrigerant fluid is present in the main loop 22, for example due to excess refrigerant fluid leaking through a seal in the compression device 10 or turbo compressor 13, the valve 26 opens to allow a predetermined amount of refrigerant fluid from the refrigerant fluid tank 28 to flow through the regulating branch 25 to the main loop 22.

[0041] In either case above, the valve 26 closes again after the amount of refrigerant fluid present in the main loop 22 reaches an optimum amount which will maximize the performance of the cooling circuit 4 .

[0042] The opening and closing of the valve 26 may depend on a signal provided by the pressure sensor 27. The pressure sensor 27 may thus be configured to detect whether the measured pressure of the refrigerant fluid exceeds a first pressure threshold, which indicates an excess of refrigerant fluid in the main loop 22, and ensure that the valve 26 is opened to allow the refrigerant fluid to flow out.

[0043] Pressure sensor 27 may also detect if the measured pressure of refrigerant fluid is below a second threshold, which is lower than the first pressure threshold, meaning that in such a configuration, refrigerant fluid is not present in sufficient quantity in main loop 22. Pressure sensor 27 then sends a signal to ensure valve 26 opens to allow refrigerant fluid from refrigerant fluid tank 28 into main loop 22.

[0044] Advantageously, the regulating branch 25 is connected to the same section in which the pressure sensor 27 measures the pressure of the refrigerant fluid. In Fig. 1, the pressure sensor 27 and the regulating branch 25 are arranged between the compression device 10 and the compression member 14 of the turbo compressor 13. The cooling circuit 4 according to the invention thus allows the amount of cooling medium flowing through the main loop 22 to be adjusted so that the gas contained in the tank is optimally cooled by the heat exchange taking place in the heat exchanger 17.

[0045] Figure 2 shows a cooling circuit 4 with two adjustment branches 25. The above-mentioned are the only structural differences with respect to the cooling circuit 4 shown in Figure 1. Therefore, reference can be made to the same description for all elements common to the two representative embodiments of the cooling circuit 4 according to the invention.

[0046] Thus, the cooling circuit 4 shown in FIG. 2 comprises a first regulating branch 71 and a second regulating branch 72. Each of the regulating branches 25 comprises its own valve 26, namely a first valve 73 arranged in the first regulating branch 71 and a second valve 74 arranged in the second regulating branch 72. The second regulating branch 72 is installed in the low-pressure section of the main loop 22, more precisely between the second flow passage 24 of the internal heat exchanger 18 and the compression device 10. The first regulating branch 71 is arranged in the same section as the regulating branch 25 shown in FIG. 1. It should be noted that the cooling circuit 4 comprises only one regulating branch 25. This regulating branch 25 may be similarly arranged in the section of the main loop 22 in which the second regulating branch 72 shown in FIG. 2 is arranged and may solely ensure the inflow and / or outflow of refrigerant fluid to and from the main loop 22.

[0047] The cooling circuit 4 also comprises two pressure sensors 27, including a first pressure sensor 75 measuring the pressure of the refrigerant fluid between the compression device 10 and the compression member 14 of the turbo compressor 13, and a second pressure sensor 76 measuring the pressure of the refrigerant fluid between the second flow path 24 of the internal heat exchanger 18 and the compression device 10. The presence of the two pressure sensors 27 allows the pressure of the refrigerant fluid to be better controlled over time and to check whether one of the two pressure thresholds mentioned above is exceeded.

[0048] In FIG. 2, the first regulating branch 71 extends to the outlet 29 to the atmosphere, whereas the second regulating branch 72 extends to the refrigerant fluid tank 28. It is understood that the first regulating branch 71 is dedicated to the refrigerant fluid outlets outside the main loop 22, and the second regulating branch 72 is dedicated to the refrigerant fluid inlets inside the main loop 22. Such an arrangement is advantageous in that it is easier to discharge the refrigerant fluid outside the main loop 22 when the refrigerant fluid is at high pressure. Similarly, it is easier to allow the refrigerant fluid to enter the main loop 22 when the refrigerant fluid flowing through the main loop is at low pressure. The opening and closing of the valve 26 functions in the same way as described in FIG. 1 and depends on the pressure of the refrigerant fluid measured by each of the pressure sensors 27.

[0049] 3 shows a first embodiment of a gas supply cooling system 1 comprising the above-mentioned cooling circuit 4. The gas supply cooling system 1 may be installed in a floating structure suitable for transporting and / or storing a gas in liquid form, for example in a tank 2. The gas is for example natural gas or ethane. The liquid gas is stored at very low temperature in the tank 2. During transport, for various reasons, for example naturally, the liquid gas may partially evaporate in the blanket 200 of the tank 2.

[0050] The gas supply cooling system 1 comprises a supply circuit 3. The supply circuit 3 is configured to suck in the evaporated gas formed in the blanket 200 of the tank 2. The gas can be used as fuel for a first gas consumer 5 and / or a second gas consumer 6. As an example, the first gas consumer 5 can be an engine providing the propulsion of the floating structure, and the second gas consumer 6 can be an auxiliary engine responsible for the electrical supply of the floating structure.

[0051] In figure 3 it can be seen that the compression device 10, which ensures the flow of refrigerant fluid in the cooling circuit 4, is also used in the supply circuit 3 to compress the evaporated gas and send this gas to the gas consumer. If the gas consumer does not require an input of energy via the gas, the gas can be removed, for example, via a burner 7. The compression device 10 can therefore be used in one or the other of the circuits.

[0052] If the refrigerant fluid is nitrogen, it is not suitable for supplying a gas consumer. To prevent deterioration of the compressor 10 during the switchover from the cooling circuit 4 to the supply circuit 3, the cooling circuit 4 may be purged completely of nitrogen by the regulating branch 25 before the compressor 10 is used to supply a gas consumer.

[0053] To isolate the compressor 10 in the supply circuit 3 or in the cooling circuit 4, the gas supply cooling system 1 comprises a series of valves. Thus, a first valve 41 is arranged in the supply circuit 3 upstream of the compressor 10 and upstream of the connection point to the cooling circuit 4. A second valve 42 is arranged in the supply circuit 3 downstream of the compressor 10 and downstream of the connection point to the cooling circuit 4. A third valve 43 is arranged in the cooling circuit 4 downstream of the compressor 10 and downstream of the connection point to the supply circuit 3. A fourth valve 44 is arranged in the cooling circuit 4 upstream of the compressor 10 and upstream of the connection point to the supply circuit 3.

[0054] Thereby, when the first valve 41 and the second valve 42 are in the open position and the third valve 43 and the fourth valve 44 are in the closed position, the compression device 10 is integrated into the supply circuit 3 for the purpose of compressing gas for supply to a gas consuming device.

[0055] When the first valve 41 and the second valve 42 are in a closed position and the third valve 43 and the fourth valve 44 are in an open position, the compression device 10 is incorporated in the cooling circuit 4 for the purpose of compressing the refrigerant fluid to cool the gas contained in the tank 2.

[0056] The gas supply and cooling system 1 also comprises the above-mentioned liquid gas circuit 8 through which gas in liquid state flows. The gas in liquid state flows from the tank 2 through a heat exchanger 17. The liquid gas circuit 8 is responsible for managing the tank pressure by condensing the gas evaporated in the blanket 200 of the tank 2.

[0057] The gas in liquid state from the tank 2 is sucked into the liquid gas circuit 8 by the pump 19. The gas in liquid state then flows until it reaches the heat exchanger 17. It is therefore understood that the heat exchange taking place in the heat exchanger 17 is between the refrigerant fluid flowing through the cooling circuit 4 and the gas in liquid state flowing through the liquid gas circuit 8. The gas in liquid state thus cooled leaves the heat exchanger 17.

[0058] The gas in liquid state, after cooling, can return to the bottom of the tank 2 through the outlet orifice 21. Such an action is responsible for a decrease in the average temperature of the tank 2, which in turn reduces the saturation pressure of the tank 2 and thus the pressure in the tank 2.

[0059] The cooled gas in liquid state can be sprayed in the form of a spray onto the blanket 200 of the tank 2. For this purpose, the liquid gas circuit 8 is provided with a spraying member 20 that ensures the spraying of the gas in liquid state. By spraying the gas in liquid state, the evaporated gas is condensed onto the blanket 200 of the tank 2. The amount of evaporated gas is reduced by the condensation of the gas, and the internal pressure of the tank 2 is reduced. The liquid gas circuit 8 is provided with an additional valve 51 to allow or not to allow the gas in liquid state to flow.

[0060] The cooling circuit 4, and more particularly its regulation branch 25, is structurally and functionally identical to that described in Figures 1 and 2. For the function of the regulation branch 25, please therefore refer to the description of the figures.

[0061] Figure 4 shows a second embodiment of the gas supply cooling system 1. The second embodiment is distinguished from the first embodiment by including a first compression device 11 and a second compression device 12. The first compression device 11 is installed in the supply circuit 3 and the second compression device 12 is located in the cooling circuit 4. However, the function of the two compression devices is not dictated by their location in the system, which will be explained in more detail below.

[0062] Furthermore, the presence of two compressors provides redundancy to the gas supply and cooling system 1. This allows the gas supply and cooling system 1 to continue operating even if one of the compressors fails, as the other compressor can still function.

[0063] The supply circuit 3 and the cooling circuit 4 both comprise a number of valves providing access to each of the compression devices, such that the system can cater for both the need to supply gas to a gas consuming device and the need to supply refrigerant fluid to the cooling circuit. Thus, in addition to the four valves already seen in the first embodiment, the second embodiment of the gas supply cooling system 1 comprises a fifth valve 45, a sixth valve 46, a seventh valve 47, an eighth valve 48, a ninth valve 49 and a tenth valve 50.

[0064] A fifth valve 45 and a sixth valve 46 allow the connection of the first compression device 11 to the cooling circuit 4 or the connection of the second compression device 12 to the supply circuit 3 depending on the configuration of the gas supply cooling system 1 .

[0065] The seventh and eighth valves 47, 48 are installed on either side of the first compression device 11 to allow the system to be isolated when both valves are in the closed position. Closing the valves is useful if the first compression device 11 fails. The ninth and tenth valves 49, 50 allow them to be used to isolate the second compression device 12 from other parts of the gas supply cooling system 1.

[0066] In this way, all the valves make it possible to dedicate a compression device to each of the circuits or to dedicate both compression devices to the supply circuit 3 or to the cooling circuit 4. Dedicating a compression device to each of the circuits makes it possible to operate simultaneously the supply circuit 3, which supplies gas to the gas consumer, and the cooling circuit 4, which cools the gas contained in the tank 2 using refrigerant fluid. If both compression devices are dedicated to only one or the other of the circuits, only one of the above mentioned functions is provided.

[0067] As in the first embodiment, assuming that the refrigerant fluid is nitrogen, in order to prevent deterioration of the gas consuming device during the switching of the compression device 11 and / or the compression device 12 from the cooling circuit 4 to the supply circuit 3, the cooling circuit 4 may be purged to completely remove the nitrogen, for example by means of the regulating branch 25, before the compression device or devices are used to supply the gas consuming device.

[0068] The second embodiment is also distinguished from the first embodiment in that the first regulating branch 71 is connected to the refrigerant fluid tank 28 and the second regulating branch 72 is connected to the outlet 29 to the atmosphere. Such an arrangement may be realised for example due to mechanical dimensions or stresses in the piping connections.

[0069] The remaining parts of the gas-supplied cooling system 1 are structurally and / or functionally identical to those described above, i.e. for structural and functional details of the gas-supplied cooling system 1 see the description of Fig. 3 and for structural and functional details of the cooling circuit 4 see the description of Figs. 1 and 2.

[0070] Naturally, the invention is not limited to the examples given above, to which many adaptations can be made without departing from the scope of the invention.

[0071] The invention described above allows the proposal of a cooling circuit suitable for adjusting the amount of refrigerant fluid in the cooling circuit so as to achieve the set goals and optimize the cooling performance of the gas contained in the tank of the floating structure. Variations not described in this specification may also be implemented without departing from the scope of the invention, as long as they constitute a cooling circuit according to the invention.

Claims

1. A cooling circuit (4) for a gas supply cooling system (1) of a floating structure comprising at least one tank (2) adapted to contain a gas in liquid state, said cooling circuit (4) being circulated by a refrigerant fluid intended to reduce the temperature of said gas in liquid state contained in said tank (2), said cooling circuit (4) comprising a main loop (22), said main loop (22) comprising: at least one compression device (10) that brings about the compression of said refrigerant fluid; at least one heat exchanger (17) configured for heat exchange between said refrigerant fluid and said gas contained in said tank (2); at least one internal heat exchanger (18) comprising a first flow path (23) through which the refrigerant fluid flows at a first pressure and a second flow path (24) through which the refrigerant fluid flows at a second pressure lower than the first pressure, the first flow path (23) being arranged downstream of the compression device (10) and upstream of the heat exchanger (17), and the second flow path (24) being arranged downstream of the heat exchanger (17) and upstream of the compression device (10); at least one turbocompressor (13) provided with a compression element (14) arranged between the compression device (10) and the first flow path (23) of the internal heat exchanger (18), and a turbine (15) arranged between the first flow path (23) of the internal heat exchanger (18) and the heat exchanger (17), The turbine (15) is a turbo compressor (13) that is rotationally connected to the turbine (15) by a shaft (16); Equipped with The cooling circuit (4) comprises a regulation branch (25) connected to the main loop (22), the regulating branch (25) comprises at least one valve (26) configured to control the flow of refrigerant fluid within the regulating branch (25); The main loop (22) comprises at least one pressure sensor (27); Based on the pressure measured by the pressure sensor (27), the valve (26) controls the amount of refrigerant fluid present in the main loop (22). A cooling circuit (4).

2. the valve (26) is configured to allow refrigerant fluid to exit the main loop (22) via the regulating branch (25) when the pressure measured by the pressure sensor (27) is greater than a first pressure threshold. A cooling circuit (4) according to claim 1.

3. the valve (26) is configured to allow refrigerant fluid to enter the main loop (22) via the regulating branch (25) when the pressure measured by the pressure sensor (27) is below a second pressure threshold, the second pressure threshold being lower than the first pressure threshold. A cooling circuit (4) according to claim 2.

4. the regulation branch (25) connects to the main loop (22) downstream of the compression device (10) and upstream of the compression member (14) of the turbocompressor (13); the pressure sensor (27) is configured to measure the pressure in the main loop (22) between the compression device (10) and the compression member (14) of the turbo compressor (13); A cooling circuit (4) according to claim 1.

5. the regulation branch (25) is connected to the main loop (22) downstream of the second flow path (24) of the internal heat exchanger (18) and upstream of the compressor (10); the pressure sensor (27) is configured to measure the pressure in the main loop (22) between the second flow path (24) of the internal heat exchanger (18) and the compressor (10); A cooling circuit (4) according to claim 1.

6. the adjustment branch (25) is a first adjustment branch (71) connected to the main loop (22) downstream of the compression device (10) and upstream of the compression member (14) of the turbo compressor (13); the cooling circuit (4) comprises a second regulating branch (72) connected to the main loop (22) downstream of the second flow path (24) of the internal heat exchanger (18) and upstream of the compressor (10); The main loop (22) comprises two pressure sensors (27), a first pressure sensor (75) configured to measure the pressure in the main loop (22) between the compression device (10) and the compression member (14) of the turbo compressor (13), and a second pressure sensor (76) configured to measure the pressure in the main loop (22) between the second flow path (24) of the internal heat exchanger (18) and the compression device (10). A cooling circuit (4) according to claim 1.

7. The first regulating branch (71) controls the outflow of the refrigerant fluid from the main loop (22); The second regulating branch (72) controls the flow of the refrigerant fluid into the main loop (22). A cooling circuit (4) according to claim 6.

8. The first regulating branch (71) controls the flow of the refrigerant fluid into the main loop (22); The second regulating branch (72) controls the outflow of the refrigerant fluid from the main loop (22). A cooling circuit (4) according to claim 6.

9. the cooling circuit (4) comprises an additional exchanger (38) arranged between the compression element (14) of the turbo compressor (13) and the first flow path (23) of the internal heat exchanger (18); The additional exchanger (38) is configured to cool the refrigerant fluid. A cooling circuit (4) according to claim 1.

10. the refrigerant fluid is nitrogen; A cooling circuit (4) according to claim 1.

11. A gas supply and cooling system (1) for a floating structure, comprising at least one tank (2) adapted to contain gas in a liquefied state, and a supply circuit (3) through which the gas is intended to flow, the supply circuit (3) being adapted to supply the gas from the tank to at least one gas consumer (5, 6) equipped on the floating structure, The gas supply cooling system (1) comprises a cooling circuit (4) according to any one of claims 1 to 10. A gas supply cooling system (1) characterized in that:

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