Supply and cooling system for a floating structure

Abstract

The invention relates to a supply and cooling system (1) comprising: a supply circuit (5); a return line (7); a first heat exchanger (8) configured to exchange heat between the gas circulating in the supply circuit (5) and the gas circulating in the return line (7); a refrigeration loop (9) including an internal heat exchanger (15) configured to exchange heat between the refrigerant circulating in the first passage (16) and the second passage (17); characterised in that the supply circuit (5) comprises a first branch (21) and a second branch (22), the first branch (21) passing through the first heat exchanger (8), and the internal heat exchanger (15) comprises at least a third passage (23) constituting the second branch (22).

Description

Technical Field

[0001] The present invention relates to the field of floating structures for storing and / or transporting liquid gas, and more particularly to a gas supply and cooling system installed in such a floating structure. Background Art

[0002] During a voyage performed by a floating structure comprising a liquid gas tank intended to be transported to a destination point, the ship is able to use at least a portion of said liquid gas in order to supply at least one of its engines through a gas supply system. At the same time, it is necessary to maintain the pressure inside the tank at an acceptable level, in particular by maintaining the liquid gas cargo at an appropriate temperature. To this end, the floating structure may also include cooling means to directly or indirectly reliquefy the vaporous gas formed in the tank.

[0003] It is therefore known to use a supply circuit to suck in boil-off gas and then compress it in order to supply the engine(s). In parallel or alternatively, the pressure inside the tank can be reduced by combining a cooling device with a refrigeration circuit to circulate a refrigerant in order to reliquefy part of the gas that has evaporated inside the tank.

[0004] A refrigeration cycle configuration such as that described above may include a so-called turbo Brayton cycle, which corresponds to a Brayton cycle including a turbocharger. Thus, the refrigeration cycle circulates a refrigerant that contributes to cooling the gas.

[0005] The use of a turbo-Brayton cycle as a refrigeration loop within the system for supplying and cooling the gas contained in the tank is effective, but has been found to be no more effective than some other devices. Summary of the invention

[0006] The present invention allows implementing such a cycle by proposing a gas supply and cooling system for a floating structure, comprising at least one tank configured to contain a gas, so as to improve its cooling performance, the supply and cooling system comprising:

[0007] at least one supply circuit, comprising at least a first compression device, said supply circuit being configured to connect the tank to at least one gas consumer equipped with the floating structure,

[0008] at least one return line connected to the supply circuit downstream of the first compression device and extending to the tank,

[0009] at least one first heat exchanger configured to exchange heat between the vaporous gas circulating in the supply circuit upstream of the first compression device and the vaporous gas circulating in the return line,

[0010] at least one refrigeration circuit for passage of a refrigerant, the refrigeration circuit comprising at least: a second compression device; a heat exchanger configured to participate in managing the saturation pressure in the tank; an internal heat exchanger configured to perform heat exchange between the refrigerant flowing in at least a first passage arranged upstream of the heat exchanger and the refrigerant flowing in at least a second passage arranged downstream of the heat exchanger; a turbocharger comprising a compression member arranged between the second compression device and a first passage of the internal heat exchanger and a turbine arranged between the first passage of the internal heat exchanger and the heat exchanger, the compression member and the turbine being rotatably connected via a shaft,

[0011] It is characterized in that the supply circuit includes a dispersion point, a convergence point and at least a first branch and a second branch, the first branch and the second branch both start at the dispersion point and both end at the convergence point, the first branch passes through the first heat exchanger, and the internal heat exchanger of the refrigeration cycle includes at least a third passage constituting the second branch.

[0012] By means of the supply and cooling system according to the invention, the gas in the vaporous state leaving the tank can be utilized by circulating it through the internal heat exchanger of the refrigeration circuit. The caloric exchange thus produced improves the performance of the refrigeration circuit, thereby improving the overall cooling and reliquefaction efficiency of the supply and cooling system.

[0013] The supply loop is capable of sucking in the vaporous gas formed in the head space of the tank. The vaporous gas can be formed naturally over time or forced to form by the floating structure. In order to adjust the saturation pressure in the tank, the vaporous gas must be discharged or reliquefied. Therefore, the supply loop ensures the circulation of the vaporous gas so that the gas can be supplied to the gas consuming device. The gas consuming device can be, for example, an engine for propelling the floating structure or a generator for supplying power to the floating structure. If the vaporous gas is compressed to a suitable pressure, the vaporous gas can be supplied to the gas consuming device. In this way, the first compression device can compress the gas to a pressure compatible with the needs of the gas consuming device.

[0014] If the gas consuming appliance does not need to be supplied or if it only needs to consume a portion of the vaporous gas contained in the tank, excess compressed vaporous gas can circulate in the return line for reliquefaction. The first heat exchanger precools the vaporous gas circulating in the return line, which gas transfers its calories to the vaporous gas leaving the tank. Such precooling facilitates the subsequent reliquefaction of the gas circulating in the return line.

[0015] The refrigeration loop is a turbo-Brayton type loop, i.e. a Brayton cycle including a turbocharger. The refrigerant circulating in the refrigeration loop may be, for example, nitrogen and circulated by a second compression device. The compression member and the turbine of the turbocharger are driven to rotate together due to their mechanical connection. The turbine is driven to rotate and thus drives the shaft to rotate, which in turn drives the compression member to rotate. Therefore, the refrigerant is initially compressed by the compression member. The refrigerant then reaches the internal heat exchanger through the first passage, where the refrigerant expands by passing through the turbine.

[0016] The refrigerant then passes through the heat exchanger. In particular, it is this heat exchange that subsequently allows the saturation pressure of the tank to be managed. The refrigerant then passes through the internal heat exchanger again, but this time via the second passage. Thus, heat is exchanged in the internal heat exchanger between the refrigerant circulated at high pressure in the first passage and the refrigerant circulated at low pressure in the second passage. This heat exchange ensures thermodynamic control of the refrigeration cycle. On leaving the second passage of the internal heat exchanger, the refrigerant is compressed again by the second compression device.

[0017] The divergence point divides the supply circuit into a first branch and a second branch. The first branch is used to circulate the gaseous gas in the aforementioned first heat exchanger. The second branch is arranged in parallel with the first branch and thus circulates the gas so that it bypasses the first heat exchanger.

[0018] The second branch is used to circulate the gaseous gas so that it passes through the internal heat exchanger via the third passage. The gaseous gas leaving the tank can therefore participate in the heat exchange carried out in the internal heat exchanger and therefore in the thermal control of the refrigeration circuit. The supply and cooling system according to the invention thus makes it possible to use the low temperature of the gaseous gas at the tank outlet to further cool the refrigerant circulating in the first passage of the internal heat exchanger and thus improve its subsequent expansion, which helps to improve the heat exchange that occurs in the heat exchanger. The cooling performance of the refrigeration circuit is thus improved.

[0019] According to a feature of the invention, the supply circuit comprises a third branch arranged in parallel with the first branch and the second branch. This third branch thus directly engages the first compression device without any heat exchange. The flow through the third branch bypasses the first heat exchanger and the internal heat exchanger.

[0020] According to a feature of the invention, the supply and cooling system comprises a cooling circuit comprising at least one pump configured to extract liquid gas from the tank, a heat exchanger configured to exchange heat between the refrigerant circulating in the refrigeration circuit and the liquid gas circulating in the cooling circuit. The pump of the cooling circuit can, for example, be immersed in the bottom of the tank in order to extract the liquid gas.

[0021] The heat exchanger subcools the liquid gas by exchanging heat with the refrigerant in the refrigeration loop. Thus, the subcooled liquid gas can help manage the saturation pressure in the tank, for example by reliquefying the vapor gas.

[0022] According to a characteristic of the invention, the supply and cooling system comprises a second heat exchanger configured to exchange heat between the liquid gas circulating in the cooling circuit downstream of the heat exchanger and the vaporous gas circulating in the return line downstream of the first heat exchanger. In other words, the heat exchange occurring in the second heat exchanger allows the reliquefaction of the vaporous gas circulating in the return line. The latter has been previously precooled in the first heat exchanger, while the liquid gas circulating in the cooling circuit has been previously supercooled by passing through the heat exchanger. The supercooled gas thus allows the temperature of the vaporous gas to drop to its reliquefaction point.

[0023] According to a characteristic of the invention, the cooling circuit is connected downstream of the second heat exchanger to a return line comprising at least one end opening into the tank. Thus, the reliquefied gas and the liquid gas converge and circulate together until the end opening into the tank.

[0024] According to a feature of the invention, the end is an injection member and / or an orifice arranged in the lower part of the tank. The orifice provides a return flow into the tank so as to reduce the overall temperature of the liquid gas in the tank. The injection member injects the liquid gas into the tank head space, which promotes the condensation of the vaporous gas present in the tank head space so as to reduce the saturation pressure in the tank.

[0025] According to a feature of the invention, the supply and cooling system comprises a cooling path connected to the cooling circuit and extending up to the injection device, the injection device being configured to vaporize the liquid gas in the second branch upstream of the third passage of the internal heat exchanger. The cooling path originates from the cooling circuit and thus allows the circulation of liquid gas originating from the tank. The injection device is arranged at the second branch and vaporizes the liquid gas in the second branch in which the gaseous gas circulates. Before the liquid gas enters the internal heat exchanger through the third passage, the liquid gas is converted into a gaseous state by reducing the temperature of the gaseous gas circulating in the second branch.

[0026] Thus, the cooling path and the injection device ensure cooling of the vaporous gases originating from the tank, the temperature of which varies greatly. Such cooling may be essential since the circulation of vaporous gases at too high a temperature in the third passage may impair the operation of the internal heat exchanger, which is only able to withstand a maximum temperature difference of 28° C. between the fluids circulating in two adjacent passages. Thus, the cooling path and the injection device regulate the temperature of the gases circulating through the second branch in order to avoid any malfunction of the internal heat exchanger due to too high a temperature difference between the fluids circulating through it.

[0027] According to a characteristic of the invention, the supply and cooling system comprises detection means for detecting the temperature of the gas circulating in the second branch between the injection device and the third passage of the internal heat exchanger. The detection means may be, for example, a temperature sensor and is arranged to measure the temperature of the vaporous gas circulating through the second branch before it enters the internal heat exchanger via the third passage. This temperature check prevents the vaporous gas from impairing the correct operation of the internal heat exchanger due to excessively high temperatures, as previously described.

[0028] According to a feature of the invention, the cooling path comprises a flow control valve, and the supply and cooling system comprises a control module configured to control the flow control valve based on the temperature recorded by the detection device. The flow control valve allows more or less liquid gas to circulate until the injection device. The higher the flow rate of the liquid gas, the greater the cooling of the vaporous gas, and vice versa. Thus, depending on the temperature of the gaseous gas recorded by the detection device upstream of the third passage, the control module modifies the flow control component so as to obtain a temperature of the gaseous gas compatible with the internal heat exchanger and the refrigerant circulating therethrough.

[0029] According to a feature of the invention, the supply and cooling system includes an auxiliary supply path connected to the cooling circuit and configured to supply gas to the gas consuming appliance, and the internal heat exchanger includes a fourth passage constituting the auxiliary supply path. Such a configuration can be implemented when not enough vaporous gas is formed in the tank head space and the floating structure is not equipped with a device for forcing the liquid gas contained in the tank to vaporize. In order to compensate for the lack of vaporous gas, the gas consuming appliance can be supplied via the auxiliary supply path, and then the internal heat exchanger acts as an evaporator for the liquid gas intended to be consumed by the gas consuming appliance.

[0030] The liquid gas is sucked by the pump of the cooling circuit and then circulates in the auxiliary supply line. The liquid gas is converted into a vapor state by passing through a fourth passage of the internal heat exchanger and then supplied to the gas consuming appliance. Depending on the required pressure of the vapor gas, the auxiliary supply line can be connected to the supply circuit upstream or downstream of the first compression device.

[0031] According to a feature of the invention, the heat exchange length of the third passage of the internal heat exchanger is less than the heat exchange length of any of the first and second passages. In other words, the internal heat exchanger comprises a first end, in which a first passage inlet is provided, for example, and a second end, in which a first passage outlet is provided, for example, and the third passage inlet is arranged between the first and second ends. As previously mentioned, the temperature of the vaporous gas leaving the tank may vary, and the internal heat exchanger may not tolerate excessively high temperature differences between the fluids circulating between two adjacent passages.

[0032] The inlet of the third passage is arranged so that the refrigerant circulating in the second passage is at a temperature substantially equal to the nominal temperature of the vaporous gas leaving the tank. Therefore, the inlet of this third passage is positioned at the level of the internal heat exchanger, at which the refrigerant circulating in the second passage of the internal heat exchanger has previously accumulated calories by heat exchange with the refrigerant circulating in the first passage of the internal heat exchanger. In this configuration, even if the vaporous gas circulating in the third passage enters the internal heat exchanger at a temperature higher or lower than the nominal temperature of the vaporous gas leaving the tank, the temperature difference between the vaporous gas circulating in the third passage and the refrigerant circulating in the second passage is still limited, and there is no risk of damaging the internal heat exchanger. Such an organization makes it possible to use a cheaper heat exchanger technology.

[0033] The invention also covers a method for managing gas contained in at least one tank of a floating structure, the method being implemented by a supply and cooling system as described above, during which method:

[0034] If the speed of the floating structure is less than a defined speed threshold, the vaporous gas originating from the tank is circulated through the first branch,

[0035] If the speed of the floating structure is greater than the speed threshold, the vaporous gas originating from the tank is circulated through the second branch.

[0036] The speed threshold of the floating structure may correspond, for example, to a speed of 12 knots or 15 knots. When the speed of the floating structure is less than the speed threshold, the floating structure is considered to be traveling at a low speed or zero speed. Therefore, if the gas consumption device is an engine propelling the floating structure, the gas consumption device consumes very little vaporous gas. The latter will therefore flow preferentially in the first branch, making it possible to perform heat exchange in the first heat exchanger and ensure precooling of the vaporous gas circulating in the return line.

[0037] In case the speed of the floating structure is greater than the speed threshold, the floating structure is considered to be travelling at a medium or high speed. In this case, the vaporous gas preferentially circulates through the second branch and thus through the third path of the internal heat exchanger in order to increase the cooling capacity of the refrigeration loop. In order to switch the circulation of the vaporous gas from one branch to another, the supply and cooling system may include a set of valves that can be opened or closed based on the measured speed of the floating structure.

[0038] According to a feature of the method, when the vaporous gas originating from the tank does not circulate through the first branch and / or the second branch, said vaporous gas circulates through the third branch. The circulation in the third branch may be useful, for example, during the start-up phase of the floating structure if the temperature of the vaporous gas is incompatible with circulating said gas through the internal heat exchanger and it is not valuable to pass through the first heat exchanger. The circulation of the vaporous gas via the third branch may also be used, for example, when the refrigeration cycle is not working. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other characteristics and advantages of the invention will emerge from the following description and from several exemplary embodiments, which are given for purposes of illustration and not limitation, with reference to the accompanying schematic drawings, in which:

[0040] [ Figure 1 ] is a diagram of a first embodiment of a supply and cooling system according to the present invention,

[0041] [ Figure 2 ] is a diagram of a second embodiment of a supply and cooling system,

[0042] [ Figure 3 ] is a diagram of a third embodiment of a supply and cooling system,

[0043] [ Figure 4 ] is a structural diagram of the pathways of an internal heat exchanger integrated into the supply and cooling system. DETAILED DESCRIPTION

[0044] Figure 1 A first embodiment of a supply and cooling system 1 is shown. The supply and cooling system 1 may be integrated in a floating structure dedicated to the transport and / or storage of liquid gas, the floating structure comprising at least one tank 2 comprising liquid gas.

[0045] Therefore, the supply and cooling system 1 is configured to interact with the tank 2, in particular to regulate the saturation pressure in said tank 2. The liquid gas contained in the tank 2 can partially evaporate and form gaseous gas in the head space 3 of the tank 2. This evaporation can occur in a natural or forced manner. The gaseous gas formed in the head space 3 contributes to the increase of the saturation pressure in the tank and must therefore be evacuated or reliquefied in order to limit this pressure increase.

[0046] In order to manage the saturation pressure in the tank 2, the supply and cooling system 1 can process the gas so that it supplies at least one gas consumer 4. Figure 1In the embodiment, the supply and cooling system 1 is configured to supply two gas consumers 4. For example, the floating structure may include a high-pressure gas consumer 4 and a low-pressure gas consumer 4, wherein the high-pressure gas consumer 4 may be an engine providing propulsion for the floating structure and the low-pressure gas consumer 4 may be a generator providing power to the floating structure.

[0047] In order to ensure the supply to the gas-consuming appliances 4, the supply and cooling system 1 comprises a supply circuit 5 extending between the tank 2 and the gas-consuming appliances 4. The supply circuit 5 comprises a first compression device 6 for sucking in and compressing the gaseous gas contained in the head space 3 of the tank 2. The gaseous gas can then circulate to the gas-consuming appliances 4 in order to supply them. Depending on the nature of the gas-consuming appliances 4, the supply and cooling system 1 may comprise an additional compressor (not shown) to increase the pressure of the gaseous gas so that it is at a pressure compatible with the supply of the gas-consuming appliances 4 (multiple).

[0048] The supply and cooling system 1 also comprises a return line 7 connected to the supply circuit 5, more particularly downstream of the first compression device 6. The return line 7 thus extends from the supply circuit 5 to the tank 2. The return line 7 allows the recirculation of vaporous gas that has not yet been used to supply the gas-consuming appliances 4, if it is not necessary to supply the gas-consuming appliances 4 or if the amount of vaporous gas present is greater than that required to supply the gas-consuming appliances 4.

[0049] The vaporous gas circulating in the return line 7 is intended to be reliquefied in order to reduce the saturation pressure in the tank while avoiding the elimination of said vaporous gas that is not used to supply the gas consumer 4. To this end, the supply and cooling system 1 comprises a first heat exchanger 8 configured to exchange heat between the compressed vaporous gas circulating in the return line 7 and the liquid gas circulating in the supply circuit 5 upstream of the first compression device 6.

[0050] Thus, the first heat exchanger 8 precools the vaporous gas circulating in the return line 7 using the vaporous gas leaving the tank 2, which is at a lower temperature than the vaporous gas circulating in the return line 7. This precooling helps to promote the subsequent reliquefaction of the vaporous gas.

[0051] The supply and cooling system 1 also includes a refrigeration circuit 9, Figure 1 In the embodiment of the present invention, the refrigeration cycle 9 corresponds to a closed circuit in which a refrigerant circulates. The refrigerant circulates in the refrigeration cycle 9 in a gaseous state and may be, for example, nitrogen. The refrigeration cycle 9 is more specifically a Brayton cycle including a turbocharger 10 .

[0052] The refrigeration circuit 9 includes a second compression device 11 that allows the refrigerant to circulate in the refrigeration circuit 9. The turbocharger 10 includes a compression member 12 and a turbine 13, and the compression member 12 and the turbine 13 are connected by a shaft 14. The turbine 13 is driven to rotate and drives the shaft 14, and the shaft 14 in turn drives the compression member 12. The refrigeration circuit 9 also includes an internal heat exchanger 15, and the internal heat exchanger 15 includes a first passage 16 and a second passage 17. The refrigerant circulating in the refrigeration circuit 9 also passes through a heat exchanger 18.

[0053] Therefore, if the path of the refrigerant within the refrigeration cycle 9 is followed, the refrigerant is first compressed by the second compression device 11 and then further compressed by the compression member 12 of the turbocharger 10. The high-pressure refrigerant then circulates through the first passage 16 and then expands within the turbine 13. After expansion, the low-pressure refrigerant flows through the heat exchanger 18 and then circulates through the second passage 17 of the internal heat exchanger 15. Therefore, heat exchange is performed in the internal heat exchanger 15 between the refrigerant circulating at high pressure in the first passage 16 and the refrigerant circulating at low pressure in the second passage 17. The refrigerant is compressed again by the second compression device 11 at the outlet of the second passage 17.

[0054] The refrigeration circuit 9 described so far allows an effective cooling capacity to be achieved, but it has been determined that such a refrigeration circuit 9 is no more effective in terms of cooling capacity than another, structurally different circuit.

[0055] In order to increase the capacity of the refrigeration loop 9, the supply circuit 5 comprises a dispersion point 19 and a convergence point 20 located downstream of the dispersion point 19. The dispersion point 19 and the convergence point 20 are arranged on either side of the first heat exchanger 8, and the supply circuit 5 comprises a first branch 21 and a second branch 22 extending between the dispersion point 19 and the convergence point 20.

[0056] The first branch 21 allows the vaporous gases originating from the tank 2 to pass through the first heat exchanger 8. The second branch 22 bypasses the first heat exchanger 8 and is configured to circulate the vaporous gases inside the internal heat exchanger 15. The latter comprises a third passage 23 allowing the circulation of the vaporous gases circulating in the second branch 22 inside the internal heat exchanger 15.

[0057] By means of the second branch 22 and the third path 23, the vaporous gas leaving the tank 2 can thus be used to further cool the refrigerant circulating in the first path 16, which facilitates its subsequent expansion through the turbine 13. Since the refrigerant expands more easily, it has a better cooling capacity, which improves the overall efficiency of the refrigeration circuit 9. Another advantage of this configuration is that the vaporous gas circulating in the third path 23 can capture calories without any subsequent negative consequences.

[0058] The vaporous gas circulating in the supply circuit 5 may circulate through the first branch 21 or the second branch 22, the selection of which is optimized based on the speed of the floating structure.

[0059] Thus, when the speed of the floating structure is less than a predetermined speed threshold, such as 12 knots or 15 knots, the floating structure travels at a low speed or at zero speed. Thus, at least one of the gas consuming appliances 4, more specifically the gas consuming appliance 4 for propelling the floating structure, generates little or no consumption of vaporous gas. Thus, the vaporous gas preferentially circulates through the first branch 21, so that heat exchange can occur in the first heat exchanger 8, thereby ensuring pre-cooling of the vaporous gas circulating through the return line 7.

[0060] When the speed of the floating structure is greater than the speed threshold, the floating structure travels at a medium or high speed. In this case, the vaporous gas preferentially flows through the second branch 22 and thus through the third passage 23 of the internal heat exchanger 15 to increase the cooling capacity of the refrigeration loop 9.

[0061] The supply circuit 5 also comprises a third branch 24 mounted in parallel with the first branch 21 and the second branch 22. The third branch 24 thus allows the vaporous gas circulating in the supply circuit 5 to bypass the first heat exchanger 8 and bypass the internal heat exchanger 15. Circulating the vaporous gas through the third branch 24 is advantageous when the temperature of the vaporous gas is not sufficient to circulate it through the internal heat exchanger 15 and when there is no value in circulating it through the first heat exchanger 8. The circulation of the vaporous gas via the third branch 27 can also be used, for example, when the refrigeration cycle 9 is under maintenance or is not in operation.

[0062] In order to select through which branch the vaporous gas circulates, the first branch 21 comprises a first valve 25 , the second branch 22 comprises a second valve 26 , and the third branch 24 comprises a third valve 27 .

[0063] Each of the three valves 25, 26, 27 can be opened or closed depending on the branch 21, 22, 24 through which the vapour gas must circulate in order to maximise the performance of the supply and cooling system 1. The valves 25, 26, 27 are controlled based in particular on the speed of the floating structure and if one of the above mentioned situations forces the vapour gas to circulate through the third branch 27.

[0064] The supply system 1 also comprises a cooling circuit 28 configured to circulate liquid gas originating from the tank 2. The cooling circuit 28 comprises a pump 29 for extracting the liquid gas contained in the tank 2.

[0065] The liquid gas circulates within the cooling circuit 28 and passes through the heat exchanger 18. Therefore, it can be understood from the foregoing that the heat exchanger 18 is configured to exchange heat between the liquid gas circulating in the cooling circuit 28 and the refrigerant circulating in the refrigeration loop 9. The refrigerant thus subcools the liquid gas passing through the heat exchanger 18. Improving the performance of the refrigeration loop 9 by circulating the vaporous gas through the third passage 23 of the internal heat exchanger 15 thus allows for more effective subcooling of the liquid gas in the heat exchanger 18.

[0066] On leaving the heat exchanger, the subcooled liquid gas continues to circulate through the cooling circuit 28 until it passes through the second heat exchanger 30. The second heat exchanger 30 is configured to exchange heat between the vaporous gas circulating in the supply circuit 5, which circulates in the return line 7 and is precooled after passing through the first heat exchanger 8, and the previously subcooled liquid gas after passing through the heat exchanger 18, while the vaporous gas circulating in the supply circuit 5 circulates via the first branch 21. Thus, in this second heat exchanger 30, the vaporous gas circulating in the return line 7 is reliquefied, the subcooled liquid gas being at a sufficiently low temperature to ensure such reliquefaction.

[0067] The cooling circuit 28 continues at the outlet of the second heat exchanger 30 until it joins the return line 7, the junction of the cooling circuit 28 and the return line 7 being downstream of the second heat exchanger 30 for each of them. Such a connection makes it possible to combine the liquid gas circulating in the cooling circuit 28 with the reliquefied gas circulating in the return line 7.

[0068] Downstream of the second heat exchanger 30 and the connection to the cooling circuit 28, the return line 7 thus extends as far as the tank 2 and comprises at least one end 31 leading to said tank 2. The end 31 can be used to regulate the temperature of the gas contained in the tank 2 and / or the saturation pressure in said tank 2. The end 31 can thus be an orifice 32 or an injection member 33. The orifice 32 can be arranged at the bottom of the tank to ensure that the liquid gas returns to the area with the lowest possible temperature. The injection member 33 is located at the head space 3 of the tank 2 and injects liquid gas into the head space 3 of the tank 2 so as to condense the vaporous gas present in the head space 3 and thereby reduce the saturation pressure in the tank 2. Thus, this shows how the refrigeration loop 9 indirectly helps to regulate the pressure and / or temperature of the liquid gas contained in the tank 2.

[0069] Figure 2 A second embodiment of a supply and cooling system 1 according to the invention is shown. The second embodiment differs from the first embodiment in that the supply and cooling system 1 comprises in particular a cooling path 34 and an injection device 35 .

[0070] The cooling path 34 is connected to the cooling circuit 28 downstream of the pump 29. It is therefore liquid gas that circulates in the cooling path 34. The latter extends as far as an injection device 35, which is arranged at the second branch 22 and which vaporizes the liquid gas that circulates in the cooling path 34 in the second branch.

[0071] The purpose of this operation is to reduce the temperature of the vaporous gas circulating in the second branch 22 when the vaporous gas circulating in the second branch 22 is at too high a temperature. This cooling takes place before the vaporous gas circulates through the third passage 23 in the internal heat exchanger 15. In fact, an excessive temperature of the vaporous gas risks damaging the internal heat exchanger 15, which allows only a limited temperature difference between the two fluids circulating through two adjacent passages. Therefore, cooling of the vaporous gas is sometimes essential to maintain the correct operation of the internal heat exchanger 15.

[0072] In order to correctly regulate the temperature of the vaporous gas circulating through the second branch 22, the supply and cooling system 1 comprises a detection device 36. The latter is able to measure the temperature of the vaporous gas circulating in the second branch 22 between the injection device 35 and the third passage 23. The detection device 36 can thus be used to check whether the vaporous gas is at a suitable temperature to pass through the internal heat exchanger 15.

[0073] The second embodiment of the supply and cooling system 1 further comprises a flow control valve 37 which controls the flow of the liquid gas circulating in the cooling path 34. The higher the flow rate, the more the liquid gas is vaporized in the second branch 22, and the lower the temperature of the gaseous gas circulating in the second branch 22.

[0074] The supply and cooling system 1 finally comprises a control module 38 capable of adjusting the flow cross section of the flow control member 37 so as to vary the flow of the liquid gas circulating in the cooling path 34. The control module 38 communicates with the detection means 36. Thus, as a function of the temperature detected by the detection means 36, the control module 38 modifies the flow cross section of the control member 37 so as to keep the vaporous gas at a suitable temperature before it circulates through the third passage 23 of the internal heat exchanger 15, thus maintaining the service life and correct operation of the internal heat exchanger 15.

[0075] Apart from the above, the second embodiment of the supply and cooling system 1 has the same structural and functional features as the first embodiment. Therefore, reference will be made to all features common to both embodiments. Figure 1 Description.

[0076] Figure 3is a representation of a third embodiment of the supply and cooling system 1 . This third embodiment differs from the two previously described embodiments in particular in that it comprises an auxiliary supply path 39 which is connected to the cooling circuit 28 and extends to connect the supply circuit 5 in order to participate in supplying the gas consumers 4 .

[0077] The auxiliary supply path 39 is used when there is no vaporous gas available in the head space 3 of the tank 2 to supply the gas consuming device 4. In this configuration, the pump 29 allows the auxiliary supply path 39 to flow liquid gas.

[0078] The auxiliary supply path 39 passes through the internal heat exchanger 15. Therefore, the latter is different from the previous embodiment in that it includes a fourth passage 40 constituting the auxiliary supply path 39.

[0079] When the liquid gas passes through the internal heat exchanger 15 via the fourth passage 40, the heat exchange with the refrigerant improves the performance of the refrigeration cycle 9, as in the previously disclosed embodiment. The heat exchange also ensures the evaporation of the liquid gas circulating in the fourth passage 40. Therefore, the internal heat exchanger 15 serves as an evaporator for the liquid gas circulating in the auxiliary supply path 39.

[0080] At the outlet of the fourth passage 40, the evaporated gas continues to circulate through the auxiliary supply path 39 until it joins the supply circuit 5 and supplies the gas consuming appliance 4. Figure 3 In the embodiment, the auxiliary supply path 39 is connected to the supply circuit 5 downstream of the first compression device 6. However, for example, depending on the pressure requirement of the gas consuming device 4, the auxiliary supply path 39 can be connected to the supply circuit 5 upstream of the first compression device 6.

[0081] All structural and functional features of the third embodiment of the supply and cooling system 1 are identical to those of the first embodiment, except for the auxiliary supply path 39 and the fourth passage 40, and refer to Figure 1 Description related to the elements common to both embodiments.

[0082] Figure 4 Indicates Figure 1 and Figure 2 Detailed structures of the individual passages of the internal heat exchanger 15 are shown. As previously mentioned, if the temperature difference between the two fluids circulating through two adjacent passages is too high, the internal heat exchanger 15 may be damaged. By the second embodiment of the supply and cooling system according to the present invention, the problems associated with the temperature of the vaporous gas circulating through the third passage 23 can be significantly solved.

[0083] You can also use Figure 4 The configuration shown in FIG. 2 is used to limit the temperature difference between the vapor gas flowing through the third passage 23 and the refrigerant flowing through the second passage 17 .

[0084] The internal heat exchanger 15 comprises a first end 41 and a second end 42 which define, for example, the main dimensions of the internal heat exchanger 15. The first passage 16 and the second passage 17, which form part of a refrigeration cycle, both extend between the first end 41 and the second end 42. Therefore, the first passage 16 and the second passage 17 both have a heat exchange length L1 which is the same size as the distance between the first end 41 and the second end 42 of the internal heat exchanger 15. The temperature of the refrigerant circulating in the second passage 17 increases as it circulates in the passage in a direction from the second end 42 to the first end 41.

[0085] Figure 4 A special feature of the internal heat exchanger 15 shown in is that the inlet 43 of the third passage 23 is positioned between the first end 41 and the second end 42, for example at one of the walls parallel to the first passage 16 and the second passage 17, while the outlet 44 of the third passage 23 is positioned at one of the ends 41, 42 of the internal heat exchanger, for example the first end 41.

[0086] Therefore, the third passage 23 has a heat exchange length L2 that is smaller than the heat exchange length L1 of the first passage 16 or the second passage 17 .

[0087] This difference in length allows the refrigerant circulating through the second passage 17 to increase in temperature by initially exchanging heat only with the refrigerant circulating through the first passage 16. Therefore, the vaporous gas enters the third passage 23 via the inlet 43 at a level where the refrigerant circulating in the second passage 17 has previously captured calories and is therefore at a higher temperature than at the inlet of the second passage 17.

[0088] Such a configuration allows the refrigerant circulating in the second passage 17 to reach a temperature equal to or substantially equal to the nominal temperature of the vapor gas at the outlet of the tank. Therefore, even if the vapor gas is at a temperature greater than or less than the nominal temperature, the risk of a high temperature difference between the vapor gas circulating in the third passage 23 and the refrigerant circulating in the second passage 17 is greatly reduced.

[0089] Preferably, the temperature difference between the two fluids circulating through two adjacent passages should not exceed 28° C. If this can happen due to the temperature of the gaseous gas being too high, if the supply and cooling system is equipped with Figure 2 The injection device shown can be Figure 2 In other cases, the third passage 23 of the internal heat exchanger 15 can be bypassed, for example by passing the gas through the third branch. Figure 4The structure of the internal heat exchanger 15 disclosed in the can be integrated into any previously disclosed embodiments.

[0090] Of course, the invention is not limited to the examples that have just been described, and many modifications may be made to these examples without departing from the scope of the invention.

[0091] As just disclosed, the invention achieves its stated purpose and makes it possible to propose a supply and cooling system for a floating structure, which exploits the low temperature of the liquid gas contained in the tank in order to improve the performance of the refrigeration loop integrated into said system. Variants not disclosed herein may be implemented without departing from the context of the invention, as long as they comprise, according to the invention, a supply and cooling system according to the invention.

Claims

1. A gas supply and cooling system (1) for a floating structure, the floating structure comprising at least one tank (2) configured to contain a gas, the supply and cooling system (1) comprising: at least one supply circuit (5) comprising at least first compression means (6), said supply circuit (5) being configured to connect said tank (2) to at least one gas consumer (4) equipping said floating structure, at least one return line (7) connected to the supply circuit (5) downstream of the first compression device (6) and extending to the tank (2), at least one first heat exchanger (8) configured to exchange heat between the vaporous gas circulating in the supply circuit (5) and the vaporous gas circulating in the return line (7) upstream of the first compression device (6), At least one refrigeration circuit (9) for being passed through by a refrigerant, the refrigeration circuit (9) comprising at least: a second compression device (11); a heat exchanger (18) configured to participate in managing the saturation pressure in the tank (2); an internal heat exchanger (15) configured to perform heat exchange between the refrigerant flowing in at least one first passage (16) arranged upstream of the heat exchanger (18) and the refrigerant flowing in at least one second passage (17) arranged downstream of the heat exchanger (18); a turbocharger (10) comprising a compression member (12) arranged between the second compression device (11) and the first passage (16) of the internal heat exchanger (15) and a turbine (13) arranged between the first passage (16) of the internal heat exchanger (15) and the heat exchanger (18), the compression member (12) and the turbine (13) being rotatably connected via a shaft (14), Characterized in that the supply circuit (5) comprises a dispersion point (19), a convergence point (20), and at least a first branch (21) and a second branch (22), wherein the first branch (21) and the second branch (22) both start at the dispersion point (19) and both end at the convergence point (20), the first branch (21) passes through the first heat exchanger (8), and the internal heat exchanger (15) of the refrigeration loop (9) comprises at least a third passage (23) constituting the second branch (22).

2. The supply and cooling system (1) according to claim 1, wherein: The supply circuit (5) comprises a third branch (24) arranged in parallel with the first branch (21) and the second branch (22).

3. The supply and cooling system (1) according to any one of the preceding claims, comprising a cooling circuit (28), the cooling circuit (28) comprising at least one pump (29), the pump (29) being configured to extract liquid gas from the tank (2), the heat exchanger (18) being configured to exchange heat between the refrigerant circulating in the refrigeration circuit (9) and the liquid gas circulating in the cooling circuit (28).

4. The supply and cooling system (1) according to claim 3, comprising a second heat exchanger (30) configured to exchange heat between liquid gas circulating in the cooling circuit (28) downstream of the heat exchanger (18) and vaporous gas circulating in the return line (7) downstream of the first heat exchanger (8).

5. Supply and cooling system (1) according to claim 4, wherein: The cooling circuit (28) is connected downstream of the second heat exchanger (30) to the return line (7), the return line comprising at least one end (31) leading to the tank (2).

6. Supply and cooling system (1) according to claim 5, wherein: The end (31) is an injection member (33) and / or an orifice (32) arranged in a lower portion of the tank (2).

7. The supply and cooling system (1) according to any one of claims 3 to 6, comprising a cooling path (34) and an injection device (35), wherein the cooling path (34) is connected to the cooling circuit (28) and extends to the injection device (35), wherein the injection device (35) is configured to vaporize liquid gas in the second branch (22) upstream of the third passage (23) of the internal heat exchanger (15).

8. Supply and cooling system (1) according to claim 7, comprising detection means (36) for detecting the temperature of the gas circulating in the second branch (22) between the injection device (35) and the third passage (23) of the internal heat exchanger (15).

9. Supply and cooling system (1) according to claim 8, wherein: The cooling path (34) comprises a flow control valve (37), and the supply and cooling system (1) comprises a control module (38) configured to control the flow control valve (37) based on the temperature recorded by the detection device (36).

10. The supply and cooling system (1) according to any one of claims 3 to 9, comprising an auxiliary supply path (39) connected to the cooling circuit (28) and configured to supply gas to the gas consuming appliance (4), the internal heat exchanger (15) comprising a fourth passage (40) constituting the auxiliary supply path (39).

11. Supply and cooling system (1) according to any one of the preceding claims, wherein: The heat exchange length (L2) of the third passage (23) of the internal heat exchanger (15) is smaller than the heat exchange length (L1) of any one of the first passage (16) and the second passage (17).

12. A method for managing gas contained in at least one tank (2) of a floating structure, said method being implemented by means of a supply and cooling system (1) according to any one of the preceding claims, during which: If the speed of the floating structure is less than a defined speed threshold, the vaporous gas originating from the tank (2) circulates through the first branch (21), If the speed of the floating structure is greater than the speed threshold, the vaporous gas originating from the tank (2) circulates through the second branch (22).

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