System for supplying gas to at least one gas consumer of floating structure

Abstract

The invention relates to a gas supply system (1) for a gas consumer (3, 3a, 3b), comprising: a first circuit (4) for supplying gas to the gas consumer (3, 3a, 3b); a gas return line (6) connected to the first supply circuit (4), the supply system (1) comprising at least one heat exchanger (7); a second gas supply circuit (8) for the gas consumers (3, 3a, 3b), the second gas supply circuit (8) comprising an evaporation device (10) configured to evaporate a liquid gas, characterized in that the return line (6) and the second supply circuit (8) share a common section (11), the common section (11) is arranged downstream of the heat exchanger (7) and upstream of the evaporation device (10).

Description

Technical Field

[0001] The present invention relates to the field of liquid gas storage and / or transport floating structures and more particularly to a gas supply system for at least one gas consuming appliance comprised in such a floating structure. Background Art

[0002] During a journey of a ship comprising at least one liquefied gas tank, the ship can use at least a portion of said liquefied gas in order to supply at least one of its gas consuming appliances via the gas supply system, said liquefied gas being intended to be consumed and / or delivered to a destination point.

[0003] In general, it is known that the gas evaporated in the tank is preferably consumed in order to supply the gas consuming appliance. This evaporation may occur due to the overall increase in tank temperature over time, and the generated vapor gas must be evacuated to avoid overpressure of the tank. The gas is supplied to the gas consuming appliance using the above-mentioned supply system. Potential excess vapor gas can be returned to the tank via a return line, but cannot be returned to the tank without first cooling.

[0004] When there is too little gas in vapor form to meet the supply requirements of the gas-consuming appliance, the supply system can also cope with the problem by taking the gas in liquid form from the tank and vaporizing it before sending it to the gas-consuming appliance.

[0005] All these functions of such a supply system necessarily require a large amount of material, such as piping, which inevitably results in a significant space and machinery footprint, even more so if the floating structure is equipped with multiple tanks. This large footprint can be problematic if one wishes to modify the supply system by adding functionality and therefore more material must be added. Thus, the lack of space can hamper any potential improvements to certain supply systems. Summary of the invention

[0006] The present invention makes it possible to overcome this problem of space and mechanical volume and, for this purpose, proposes a system for supplying gas to at least one gas-consuming appliance of a floating structure, the floating structure comprising at least one tank configured to contain gas, the supply system comprising:

[0007] at least one first circuit for supplying gas to said gas-consuming appliance, comprising at least one compression device configured to compress the gas obtained in the vapor state in said tank to a pressure compatible with the requirements of said gas-consuming appliance,

[0008] a gas return line connected to the first supply circuit downstream of the compression device and extending to the tank, the supply system comprising at least one heat exchanger configured to effect a heat exchange between the gas circulating in the first supply circuit and the gas circulating in the return line,

[0009] at least one second gas supply circuit for the gas consuming appliance, comprising at least one pump configured to pump liquid gas taken from the tank and at least one evaporation device configured to evaporate the liquid gas,

[0010] Characterized in that the return line and the second supply circuit share a common section, and the common section is configured to circulate gas in a first flow direction or in a second flow direction opposite to the first flow direction.

[0011] Thanks to the supply system according to the invention, the return line and the second supply circuit can be partially combined so as to limit the number of pipes required to design the supply system. This is useful when adding elements to a supply system that is already partially installed inside a floating structure. For example, since part of the pipe for the return line is already part of the second supply circuit, the return line and the exchanger can be conveniently added to a floating structure that already includes a first supply circuit and a second supply circuit. This avoids the need for additional pipes that take up more space in the supply system, thereby simplifying the system. Another advantage is that the number of lines that pass through the tank is reduced, thereby limiting the risk of tank seal failure.

[0012] The first supply circuit takes the vapor gas formed in the tank and uses it as a fuel for the gas-consuming appliance. Despite the insulating properties of the tank, the gas in the vapor state forms naturally over time and must be treated in some way to limit the pressure buildup in the tank. The first supply circuit thus enables it to be used as a fuel for the gas-consuming appliance. In addition to extracting the vapor gas from the tank, the compression device also increases the gas pressure to a pressure compatible with the gas-consuming appliance, for example between 6 and 18 bars.

[0013] The gas consuming appliance may for example be an engine for propelling the floating structure, or a generator for supplying power to the floating structure. The supply system may also be capable of supplying a plurality of gas consuming appliances, in which case the first supply circuit is correspondingly adapted to be capable of supplying gas in the vapor state to each gas consuming appliance.

[0014] The return line is connected to the first supply loop downstream of the compression device and allows the circulation of vapor state gas that exists in excess of the supply requirements of the gas consuming appliances. This excess vapor state gas is not wasted, but circulates in the return line so that it can be returned to the tank vapor. As the gas returns, the heat exchanger cools the gas by exchanging heat with the vapor gas leaving the tank and circulating in the first supply loop. Thus, the excess vapor state gas is conserved by returning to the tank, rather than being burned or released into the atmosphere.

[0015] The second supply circuit is used in case of a shortage of vapor gas in the tank to meet the supply requirements of the gas consuming appliance. The pump enables the gas to be taken out of the liquid state and increases the pressure to a pressure compatible with the gas consuming appliance. The evaporation device evaporates the gas into a liquid state so that the gas can then be consumed by the gas consuming appliance. The evaporation of the gas into the liquid state can be performed, for example, by heat exchange with a third party fluid (e.g. seawater).

[0016] The common section is part of both the return line and the second supply loop to avoid increasing the number of pipes in the supply system. The partial combination of the return line and the second supply loop is advantageous because the return line is used when the vapor gas is in excess relative to the requirements of the gas-consuming appliance, while the second supply loop is used when the amount of vapor gas is too small or absent to meet the requirements of the gas-consuming appliance itself. In this way, the return line and the second supply loop are never used at the same time. . It is therefore entirely feasible to use a section common to both the return line and the second supply loop without affecting the overall operation of the supply system.

[0017] The term "common section" refers to a pipe section shared by the second supply circuit and the return line. Thus, the common section is configured to circulate the gas in a first flow direction or in a second flow direction opposite to the first flow direction. In fact, when the gas flows in the return line, it flows back to the tank, while when the gas flows in the second supply circuit, it flows from the tank to the gas-consuming appliance, opposite to the direction of the gas flowing in the return line.

[0018] According to an optional feature of the invention, the common section is connected between the heat exchanger and the evaporator device.According to one example, the common section is fluidly connected to the circuit downstream of the heat exchanger and upstream of the evaporator device, seen in the same gas flow direction.

[0019] According to one feature of the present invention, the common section includes a first end and a second end, the return line and the second supply circuit are separated from the first end and the second end, and the common section is configured to circulate the gas flowing in the return line according to a first flow direction from the first end toward the second end, and to circulate the gas flowing in the second supply circuit according to a second flow direction from the second end toward the first end.

[0020] The first end and the second end define the common section and each constitute a junction between the return line and the second supply circuit. As described above, the gas does not flow in the same direction, depending on whether the gas flows in the return line or in the second supply circuit. The first end corresponds to the end of the common section farthest from the tank, while the second end corresponds to the end of the common section closest to the tank. Therefore, the gas does not flow from the same end to the same other end, depending on whether the gas flows in the return line or in the second supply circuit.

[0021] According to one feature of the invention, the return line comprises a branch configured to extend from the second end of the common section to the bottom of the tank. The branch corresponds to the portion of the return line extending between the common section and the tank. This is independent of the second supply circuit so as not to damage the pump immersed in the tank and forming part of the second supply circuit.

[0022] Advantageously, the branch can be positioned completely at the bottom of the tank or at least immersed inside the tank. In terms of functionality, this variant does not differ from a branch arranged at the center of a pipe of the supply system. However, placing the branch inside the tank avoids having to arrange more pipes at the center of the supply system, which helps to limit the spatial footprint of the supply system.

[0023] According to one feature of the invention, the branch comprises an ejector configured to be arranged at the bottom of the tank. This is a first embodiment of the supply system according to the invention. In this first embodiment, the ejector is the last element in the return line before the gas flowing through it returns to the tank. Although the heat exchanger cools the gas in the vapor state, this cooling is not sufficient to reliquefy the gas circulating in the return line. The ejector compensates for this by mixing the vapor gas circulating in the return line with the liquid gas at the bottom of the tank, so that the vapor gas is released in its liquid state at the bottom of the tank. The ejector is ideally located as far down as possible in the tank, since the temperature of the gas in the liquid state is lowest at the bottom of the tank.

[0024] According to one feature of the invention, the heat exchanger is a first heat exchanger, the supply system comprises a cooling circuit and a second heat exchanger, the cooling circuit comprises a pumping device configured to pump the liquid gas taken from the tank, and the second heat exchanger is configured to achieve heat exchange between the vapor state gas circulating in the return line and the liquid gas circulating in the cooling circuit. This is a second embodiment of the supply system according to the invention.

[0025] In this second embodiment, the vapor gas is liquefied by two heat exchangers before returning to the tank. This method ensures that the gas flowing in the return line returns directly to the liquid state.

[0026] The cooling circuit allows the gas to be pumped into the tank in a liquid state and enables the vapor gas to be liquefied by circulating through a second heat exchanger.

[0027] According to one feature of the present invention, the first heat exchanger is configured to cool the vapor gas flowing in the return line, and the second heat exchanger is configured to liquefy the vapor gas flowing in the return line. In other words, the vapor gas first flows through the first heat exchanger to be pre-cooled by heat exchange with the vapor gas flowing in the first supply circuit, and then flows through the second heat exchanger to be condensed by heat exchange with the liquefied gas flowing in the cooling circuit. Therefore, from the perspective of gas circulation in the return line, the second heat exchanger is located downstream of the first heat exchanger.

[0028] According to one feature of the invention, the cooling circuit and the return line are connected together downstream of the second heat exchanger and upstream of the first end of the common section. In other words, the reliquefied gas flowing in the return line and the liquid gas flowing in the cooling circuit are combined at the outlet of the second heat exchanger before traveling through the common section and then returning to the tank. This configuration helps to limit the number of pipes in the supply system according to the invention.

[0029] According to one feature of the invention, the supply system comprises at least one control member configured to control the airflow within the return line and / or the second supply circuit and / or the branch. The control member manages the airflow within the supply system as a function of the activity of the supply system and therefore as a function of the airflow direction within the common section. Advantageously, the system comprises a plurality of control members to improve the management of the airflow within the supply system.

[0030] The control member may be, for example, a valve or any other element configured to allow or inhibit gas flow within a specific section. According to another non-exhaustive example, the control member may be a check valve or any other element that allows gas flow in one direction but prevents gas flow in the opposite direction.

[0031] The invention also covers a floating structure for transporting and / or storing liquid gas, the floating structure comprising at least one tank configured to contain gas, at least one gas consumer and at least one supply system as described above.

[0032] The invention also covers a method for supplying at least one gas consuming appliance of a floating structure, the floating structure comprising at least one tank configured to contain gas, the method being implemented by a supply system as described above, during which method:

[0033] - when the amount of vapor gas contained in the tank is greater than the supply demand of the gas consuming appliance, excess vapor gas is supplied from the vapor gas contained in the tank to the gas consuming appliance through the first supply circuit, the excess vapor gas flows in the return line, and the excess gas flows in the common section along a first flow direction,

[0034] -When the amount of gaseous liquid contained in the tank is less than the supply demand of the gas consuming appliance, the gas consuming appliance is supplied with liquid gas contained in the tank at least through the second supply circuit, and the liquid gas flows in the common section along a second flow direction opposite to the first flow direction.

[0035] The order of the supply methods and therefore the direction of gas flow within the common section depends on the amount of vapour gas present in the tank and the supply requirements of the gas consuming appliances. The supply system may be configured to supply gas to multiple gas consuming appliances, in which case the need to supply all gas consuming appliances must be considered. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Other features and advantages of the invention will emerge from the following description and from several exemplary embodiments, which are given for illustrative purposes and not for limitation with reference to the accompanying schematic drawings, in which:

[0037] [ Figure 1 ] is a schematic diagram of a first embodiment of a supply system according to the invention arranged in a floating structure provided with at least one gas consuming appliance,

[0038] [ Figure 2 ] is a schematic diagram of the gas circulation in the first mode of the supply system design when the gas supply in the vapor state exceeds the supply requirement of the gas consuming appliance,

[0039] [ Figure 3 ] is a diagram of the gas circulation in the first type of supply system when the gas supply in the vapor state is too small to meet the supply requirements of the gas consuming appliances,

[0040] [ Figure 4 ] is a schematic diagram of a second embodiment of a supply system according to the present invention,

[0041] [ Figure 5 ] is a schematic diagram of the gas flow in the second embodiment of the supply system when the gas supply in the vapor state exceeds the supply requirement of the gas consuming device,

[0042] [ Figure 6 ] is a schematic diagram of the gas circulation in the second embodiment of the supply system when the gas supply in the vapor state is too small to meet the supply requirements of the gas consuming device,

[0043] [ Figure 7 ] is a schematic diagram of a first embodiment of a supply system according to the present invention, which is suitable for a floating structure including two tanks configured to contain gas. DETAILED DESCRIPTION

[0044] Figure 1 is a schematic diagram of a first embodiment of a gas supply system 1 according to the invention, which supply system 1 can be integrated, for example, into a floating structure for transporting and / or storing liquid gas, for example natural gas, also called LNG. The floating structure comprises at least one tank 2 for transporting and / or storing liquid gas and at least one gas consumer 3, which can be, for example, an engine for propelling the floating structure or a generator for supplying power to the floating structure.

[0045] The tank 2 is constructed to ensure sealing and thermal insulation with respect to the liquid gas it contains. However, over time, the liquid gas present in the tank 2 partially evaporates, causing an increase in the saturation pressure of the tank 2. Therefore, the supply system 1 prevents potential overpressure inside the tank 2 by exhausting the vapor gas form from the tank.

[0046] For this purpose, the supply system 1 comprises a first supply circuit 4 extending between the tank 2 and the gas-consuming appliance 3. The first supply circuit 4 comprises a compression device 5 configured to suck in the vapor gas present in the tank 2. Furthermore, the compression device 5 is also configured to increase the pressure of the vapor gas so that the vapor gas has a pressure compatible with the requirements of the gas-consuming appliance 3. Thus, the first supply circuit 4 regulates the saturation pressure of the tank 2 and supplies the gas-consuming appliance 3 with fuel, which fuel must of course be compatible with the properties of the gas contained in the tank 2.

[0047] The supply system 1 further comprises a return line 6 which is connected to the first supply circuit 4 downstream of the compression device 5 and extends to the tank 2. The return line 6 is used in case of excess vapour gas compared to the supply requirement of the gas consuming appliance 3. The excess gas then returns to the tank 2 via the return line 6, but must first be cooled.

[0048] To this end, the supply system 1 comprises a heat exchanger 7 which is configured to act as a heat exchanger between the vapor gas circulating in the first supply loop 4 and the vapor gas circulating in the return line 6 , thereby cooling the vapor gas circulating in the return line 6 before it returns to the tank 2 .

[0049] The supply system 1 also includes a second supply circuit 8, which is used when there is too little vapor gas to meet the supply requirements of the gas consuming appliance 3. Therefore, the second supply circuit 8 can be used in combination with the first supply circuit 4, or used alone when there is no vapor gas in the tank 2 at all.

[0050] The second supply circuit 8 comprises a pump 9 at the bottom of the tank 2, making it possible to extract liquid gas from the tank 2. The supply system 1 also comprises an evaporation device 10 for evaporating the liquid gas circulating in the second supply circuit 8 before supplying the gas consumer 3, which can only be supplied in the form of vapor gas. The evaporation can be performed, for example, by heat exchange with a third fluid, such as sea water.

[0051] Such a supply system 1 therefore comprises several supply devices as well as cooling devices before returning to the tank 2. All these devices therefore require a large amount of piping and this may lead to mechanical congestion problems, for example during the installation of a part of the supply system to complete the supply system within a given floating structure.

[0052] The supply system 1 according to the invention solves this mechanical space problem by combining a portion of the return line 6 and a portion of the second supply circuit 8 into a common section 11. In other words, the common section 11 forms part of both the return line 6 and the second supply circuit 8, thereby limiting the number of pipes required for the correct functioning of the supply system 1. More specifically, the common section 11 is arranged downstream of the heat exchanger 7 from the perspective of the return line 6 and upstream of the evaporator 10 from the perspective of the second supply circuit 8, the downstream and upstream characteristics being compared along the same flow direction.

[0053] For example, when installing the return line 6 and the heat exchanger 7 in a floating structure already equipped with the first supply circuit 4 and the second supply circuit 8, the pipes of the second supply circuit 8 can be partially used during the implementation of the return line 6 to form the common section 11, thereby limiting the number of pipes in the supply system 1. This saves costs and reduces the mechanical footprint.

[0054] The combination of the return line 6 and the second supply loop 8 is particularly advantageous because they are never used simultaneously. In fact, the return line 6 is used in the case of an excess of vapor gas in the tank 2, while the second supply loop 8 is used in the case of a shortage or absence of vapor gas in the tank 2. Therefore, the return line 6 and the second supply loop 8 can be combined in a common section 11 without interfering with the operation of each other.

[0055] It will therefore be understood that the common section 11 is configured to ensure the flow of gas in both directions, depending on the activity of the return line 6 (ensuring the flow of gas towards the tank 2) or the activity of the second supply circuit 8 (ensuring the flow of gas from the tank 2). In this way, the common section 11 comprises a first end 12 and a second end 13 corresponding to the limits of the common section 11 from which the return line 6 and the second supply circuit 8 are separated from each other.

[0056] As an example, Figure 1 As shown in the subsequent figures, the first end 12 corresponds to the end of the distal common section 11 of the tank 2, and the second end 13 corresponds to the end of the proximal common section 11 of the tank 2. Therefore, the gas can flow from the first end 12 to the second end 13 in the first flow direction 14, or flow from the second end 13 to the first end 12 in the second flow direction 15. Therefore, when the gas flows through the return line 6, the gas flows through the common section 11 along the first flow direction 14, and when the gas flows through the second supply circuit 8, the gas flows through the common section 11 along the second flow direction 15.

[0057] In particular, in order to further control the gas flow within the common section 11 , the supply system 1 comprises at least one control member 22 allowing or prohibiting the flow of gas at the level of the circuit or line where said control member 22 is arranged.

[0058] according to Figure 1 In the example shown, the supply system 1 comprises a plurality of control members 22. More specifically, the supply system 1 comprises a first control member 22a arranged on the return line 6 between the heat exchanger 7 and the first end 12 of the common section 11, and a second control member 22b arranged on the second supply circuit 8 between the first end 12 of the common section 11 and the evaporation device 10. Figures 1 to 3 In the example shown, the first control member 22a and the second control member 22b are valves that can be opened or closed depending on the air flow and the purpose of the air flow.

[0059] The return line 6 comprises a branch 16 extending between the second end 13 of the common section 11 and the tank 2. This branch 16 allows the gas to return to the tank 2 without interfering with the pump 9 of the second supply circuit 8. For this purpose, the branch 16 may also comprise a third control member 22c, also in the form of a valve, which may be switched between an open position and a closed position depending on the gas flow and the use to which it is put.

[0060] In a first embodiment of the supply system 1, the branch 16 extends to the tank 2 and comprises an ejector 17 immersed in the bottom of the tank 2. The ejector 17 mixes the vapor gas circulating in the return line 6 with the liquid gas at the bottom of the tank 2 so that the vapor gas is released in a liquid state at the bottom of the tank 2. This configuration can lead to an increase in the overall temperature of the liquid gas contained in the tank 2. To compensate for this, a refrigeration device (not shown) can compensate for this temperature increase by cooling the liquid gas in the tank 2.

[0061] Furthermore, the second supply circuit 8 comprises a fourth control member 22d between the pump 9 and the second end 13 of the common section 11. The fourth control member 22d takes the form of a non-return valve which prevents the gas from flowing in one direction from the second end 13 of the common section 11 towards the pump 9, thus optimizing the flow of gas coming from the return line 6 and forcing it to flow in the branch 16.

[0062] Figure 2 and Figure 3 The gas flow in the first embodiment of the supply system 1 is shown respectively when the vapor gas present in the tank 2 exceeds the requirement of the gas consuming appliance 3 and when there is too little or no vapor gas in the tank 2 to be adequately supplied. Figure 2 In FIG. 2 , the first control component 22a and the third control component 22c allow gas flow, while the second control component 22b blocks gas flow. Figure 3 In the embodiment, the first control component 22a and the third control component 22c prevent the gas flow, while the second control component 22b allows the gas flow.

[0063] exist Figure 2 and Figure 3 , a portion of the supply system 1 through which the gas flows in a liquid or vapor state is shown as a solid line, and a portion of the supply system 1 through which no gas flows is shown as a dotted line.

[0064] Figure 2 An example of a gas cycle is shown in which there is an excess of vapor gas in the tank 2. Therefore, the vapor gas is sucked in by the compression device 5 and flows in the first supply loop 4. Initially, the vapor gas passes through the heat exchanger 7 to cool the vapor gas flowing in the return line 6. At the outlet of the heat exchanger 7, the vapor gas flowing in the first supply loop 4 is then compressed by the compression device 5 to a pressure compatible with the requirements of the gas consuming appliance 3.

[0065] The vapor gas then flows to the gas consumer 3 to supply it. The amount of vapor gas supplied to the gas consumer 3 depends on the latter's supply requirements. The excess vapor gas state flows through the return line 6 at the outlet of the compression device 5. Figure 2A vapour gas flow to the gas consuming device 3 is shown, but the gas consuming device 3 may also require no vapour gas supply, in which case the vapour gas compressed by the compression device 5 then flows entirely through the return line 6 .

[0066] The vapor gas flowing in the return line 6 passes through the heat exchanger 7. Since the vapor gas flowing in the return line 6 has been previously compressed by the compression device 5, the gas is at a higher temperature than the vapor gas leaving the tank 2 and flowing in the first supply loop 4. Therefore, the vapor gas flowing in the return line 6 is cooled by passing through the heat exchanger 7.

[0067] The vapor gas continues to flow until it reaches the first end 12 of the common section 11 and then flows through the common section 11 in a first flow direction 14 to the second end 13. The vapor gas then flows through the branch 16 and is ejected at the bottom of the tank 2 by the ejector 17.

[0068] Figure 3 Shown with Figure 2 The opposite configuration, ie, the amount of gas present is too small or even non-existent, cannot meet the supply requirements of the gas consuming appliance 3 .

[0069] If vapor gas is present in the tank 2, the vapor gas flows through the first supply loop 4 and then passes through the heat exchanger 7 without heat exchange, or bypasses the heat exchanger 7 by flowing through a bypass line (not shown). The vapor gas is then compressed by the compression device 5 and continues to flow in the first supply loop 4 until it reaches the gas consumer 3. Since there is no excess gas in the vapor state, there is no gas flow in the return line 6. If vapor gas is not present in the tank 2, there is no gas flow in the first supply loop 4.

[0070] In this configuration, the shortage of gas in the vapor state is therefore compensated by using the second supply circuit 8 to meet the needs of the gas-consuming appliance 3. To this end, the pump 9 draws gas in liquid form from the tank 2. The liquid gas flows to the second end 13 of the common section 11 and then flows through the common section 11 in a second flow direction 15 to the first end 12.

[0071] The liquid gas then continues to flow in the second supply circuit 8 until it evaporates in the evaporation device 10. On leaving the latter, the evaporated gas flows through the second supply circuit 8 to supply the gas-consuming appliance 3.

[0072] Figure 4 A second embodiment of a supply system 1 according to the invention is shown. The second design differs from the first in that the vapour gas flowing in the return line 6 is reliquefied before returning to the tank 2 .

[0073] For this purpose, the Figures 1 to 3 The heat exchanger 7 shown in FIG. 7 is here a first heat exchanger 18 , which is again configured to effect a heat exchange between the vapor gas flowing in the first supply circuit 4 and the vapor gas flowing in the return line 6 .

[0074] The second embodiment of the supply system 1 further comprises a cooling circuit 19 comprising a pumping device 20 configured to suck the gas in liquid form from the tank 2. Finally, the second embodiment of the supply system 1 comprises a second heat exchanger 21 configured to exchange heat between the vapor gas flowing in the return line 6 and the liquid gas flowing in the cooling circuit 19. Thus, within this second heat exchanger 21, the vapor gas flowing in the return line is reliquefied before returning to the tank 2.

[0075] At the outlet of the second heat exchanger 21, the reliquefied gas flowing in the return line 6 and the liquid gas flowing in the cooling circuit 19 are combined upstream of the first end 12 of the common section 11 before flowing to the tank 2. The second embodiment of the supply system 1 does not comprise an ejector at the branch 16, but rather an opening at the bottom of the tank 2, when the gas is fully reliquefied.

[0076] Therefore, it should be understood that the vapor gas flowing through the reflux line 6 is first cooled in the first heat exchanger 18 and then liquefied in the second heat exchanger 21 .

[0077] Another difference between the illustrations of the two embodiments of the supply system 1 according to the invention is that Figure 4 The supply system 1 shown is configured to supply gas to a first gas consuming device 3a and a second gas consuming device 3b. As described above, the first gas consuming device 3a can be an engine for propelling a floating structure, while the second gas consuming device 3b can be a generator for supplying power to the floating structure. Advantageously, the first gas consuming device 3a and the second gas consuming device 3b have the same compatibility in terms of the pressure of the gas supplied to them (i.e., the pressure applied to the gas by the compression device 5 or the pump 9).

[0078] Therefore, the first supply loop 4 and the second supply loop 8 are both capable of supplying the first gas consuming appliance 3a and / or the second gas consuming appliance 3b, depending on the needs of each of them. However, this configuration is not specific to the second embodiment, so the first embodiment of the supply system 1 can be used to supply two or more gas consuming appliances 3a, 3b, or the second embodiment of the supply system 1 can be used to supply a single gas consuming appliance 3.

[0079] Finally, the second embodiment of the supply system 1 differs from the first embodiment in that the first control member 22a and the second control member 22b are in the form of non-return valves. The non-return valves allow gas to flow in one direction but not in the opposite direction, thereby ensuring a similar Figures 1 to 3 However, the type of control member 22 is irrelevant to the embodiment, so a valve or a check valve may be used regardless of the embodiment. The third control member 22c and the fourth control member 22d are also valves and check valves, respectively.

[0080] Since the structural and functional elements not described in this second embodiment of the supply system 1 are the same as those in the first embodiment, reference will be made to Figure 1 Description of the elements common to both embodiments.

[0081] Figure 5 and Figure 6 The gas flow in the second embodiment of the supply system 1 is shown respectively when the vapor gas in the tank 2 exceeds the requirement of the gas consuming appliances 3a, 3b, and when there is too little or no vapor gas in the tank 2 to adequately supply the gas consuming appliances.

[0082] like Figure 2 and Figure 3 As shown, in Figure 5 and Figure 6 , a portion of the supply system 1 through which liquid or vapor gas flows is shown as a solid line, while a portion of the supply system 1 through which no gas flows is shown as a dotted line.

[0083] Figure 5 An example of a gas flow is shown in which there is an excess of vapor gas in the tank 2. The vapor gas is therefore sucked in by the compression device 5 and flows in the first supply loop 4. Initially, the vapor gas passes through the heat exchanger 7 to cool the vapor gas flowing in the return line 6. At the outlet of the heat exchanger 7, the vapor gas flowing in the first supply loop 4 is then compressed by the compression device 5 to a pressure compatible with the requirements of the gas consuming appliances 3a, 3b.

[0084] Then, the steam gas flows to the first gas consuming apparatus 3a and / or the second gas consuming apparatus 3b to supply them. Depending on the requirements, the first supply loop 4 can only supply one of the two gas consuming apparatuses 3a, 3b, or supply both at the same time. This configuration can be controlled by a valve system (not shown).

[0085] The excess vapor gas state flows through the return line 6 at the outlet of the compression device 5 . Figure 5A vapour gas flow to the gas consuming appliances 3 a , 3 b is shown, but it is also possible for the gas consuming appliances 3 to require no vapour gas supply, in which case all the vapour gas compressed by the compression device 5 subsequently flows through the return line 6 .

[0086] The vapor gas flowing in the return line 6 passes through the heat exchanger 7. Since the vapor gas flowing in the return line 6 has been previously compressed by the compression device 5, the gas is at a higher temperature than the vapor gas leaving the tank 2 and flowing in the first supply loop 4. Therefore, the vapor gas flowing in the return line 6 is cooled by passing through the heat exchanger 7.

[0087] The cooled vapour gas then flows through the second heat exchanger 21. At the same time, the liquefied gas flows through the cooling circuit 19 via the pumping device 20 and also flows through the second heat exchanger 21 in order to liquefy the previously cooled vapour gas.

[0088] At the outlet of the second heat exchanger 21, the reliquefied gas and the liquid gas flowing in the cooling circuit 19 are combined and continue to flow until they reach the first end 12 of the common section 11 and then flow in the common section 11 along the first flow direction 14 to the second end 13. The mixture of the reliquefied gas and the liquefied gas from the cooling circuit 19 then flows to the bottom of the tank 2 through the branch 16.

[0089] Figure 6 Shown with Figure 5 The opposite configuration, ie the gaseous presence in too small an amount or even non-existent, cannot satisfy the supply requirements of one or both of the gas consuming devices 3a, 3b.

[0090] If there is vapor gas in the tank 2, the vapor gas flows through the first supply loop 4 and then passes through the heat exchanger 7 without heat exchange, or bypasses the heat exchanger 7 by flowing through a bypass line (not shown). The vapor gas is then compressed by the compression device 5 and continues to flow in the first supply loop 4 until it is supplied to one or both of the gas consuming appliances 3a, 3b. Since there is no excess gas in the vapor state, there is no gas flow in the return line 6. As a result, in the absence of vapor gas to be reliquefied, there is no flow of liquid gas in the cooling circuit 19. If there is no vapor gas in the tank 2, there is no gas flow in the first supply loop 4.

[0091] Therefore, in this configuration, the second supply circuit 8 is used to compensate the gas in the vapor state to meet the needs of one or both of the gas consumers 3a, 3b. To this end, the pump 9 draws the gas in liquid form from the tank 2. The liquid gas flows to the second end 13 of the common section 11 and then flows through the common section 11 in the second flow direction 15 to the first end 12.

[0092] The liquid gas then continues to flow in the second supply circuit 8 until it evaporates in the evaporation device 10. On leaving the latter, the evaporated gas flows through the second supply circuit 8 to supply the first gas consumer 3a and / or the second gas consumer 3b.

[0093] Figure 7 A variant of the first embodiment of the supply system 1 according to the invention is shown. This variant consists in applying the supply system 1 to a floating structure comprising a plurality of tanks 2a, 2b. Figure 7 In the diagram, a first tank 2a and a second tank 2b are shown, but the supply system 1 is applicable to a floating structure comprising more tanks.

[0094] Thus, the first supply circuit 4 is fluidly connected to each tank 2a, 2b, such that the compression device 5 is able to extract the vapour gas present in both tanks 2a, 2b.

[0095] The return line 6 is also fluidically connected to the two tanks 2a, 2b, each interacting with its own branch 16a, 16b and its own ejector 17a, 17b, the branches 16a, 16b all being connected to the common section 11. In other words, there are as many branches 16a, 16b and ejectors 17a, 17b as there are tanks 2a, 2b.

[0096] Figure 7 A variant of the interaction of the branch 16b with the second tank 2b is shown. The branch 16b is in fact configured to be immersed in the second tank 2b, unlike the branch 16a, which is suspended above the first tank 2a, as previously shown. The alternative positioning of the branch 16b enables the internal volume of the second tank 2b to be used for integrating said branch 16b, thus avoiding that the pipe of the branch 16b further occupies the space dedicated to the supply system 1. It should be noted that this variant also applies to the second embodiment described above.

[0097] Finally, the second supply circuit 8 is also fluidically connected to two tanks 2 a , 2 b , each interacting with its own pump 9 a , 9 b , both connected to a common section 11 .

[0098] like Figure 7 As shown, despite the presence of two tanks 2a, 2b, the supply system 1 still comprises only one common section 11. It is therefore clear that the advantage of the supply system 1 according to the invention is considerable when the floating structure comprises a plurality of tanks, since the more tanks there are, the more pipes there are. Therefore, the use of a common section 11 for the return line 6 and the second supply circuit 8 makes it possible to significantly reduce the mechanical footprint of the supply system 1 when there are a plurality of tanks in the floating structure.

[0099] Figure 2 and Figure 3The different airflows described in also apply to Figure 7 Gas may be drawn from or returned to either or both of the tanks 2a, 2b, depending on various parameters such as the volume of the tanks 2a, 2b, the amount of gas present in each of the tanks 2a, 2b or its temperature.

[0100] It is also clear that the second embodiment of the supply system 1 according to the invention is also applicable to a floating structure comprising a plurality of tanks 2a, 2b.

[0101] Of course, the invention is not limited to the embodiments that have just been described and many modifications may be made to these embodiments without departing from the scope of the invention.

[0102] As described above, the present invention achieves its stated purpose and makes it possible to provide a gas supply system for at least one gas consumer in a floating structure, said supply system ensuring a limited number of pipes required for its proper operation. Variants not described here may be implemented without departing from the context of the present invention, since according to the invention they comprise a supply system according to the invention.

Claims

1. A system (1) for supplying gas to at least one gas consuming appliance (3, 3a, 3b) of a floating structure, the floating structure comprising at least one tank (2) configured to contain gas, the supply system (1) comprising: at least one first circuit (4) which supplies gas to said gas-consuming appliance (3, 3a, 3b), said first circuit (4) comprising at least one compression device (5) configured to compress the gas obtained in the vapor state in said tank (2) to a pressure compatible with the requirements of said gas-consuming appliance (3, 3a, 3b), a gas return line (6) connected to the first supply circuit (4) downstream of the compression device (5) and extending to the tank (2), the supply system (1) comprising at least one heat exchanger (7) configured to effect a heat exchange between the gas flowing in the first supply circuit (4) and the gas flowing in the return line (6), - at least one second circuit (8) which supplies gas to the gas consuming appliances (3, 3a, 3b), the second circuit (8) comprising at least one pump (9) configured to pump liquid gas taken from the tank (2) and at least one evaporation device (10) configured to evaporate liquid gas, characterised in that the return line (6) and the second supply circuit (8) share a common section (11), the common section (11) being configured to circulate the gas in a first flow direction (14) or in a second flow direction (15) opposite to the first flow direction (14).

2. The supply system (1) according to claim 1, wherein: The common section (11) is connected between the first heat exchanger (7) and the evaporation device (10).

3. The supply system (1) according to claim 1 or 2, wherein: The common section (11) comprises a first end (12) and a second end (13), the return line (6) and the second supply circuit (8) being separated from the first end (12) and the second end (13), and the common section (11) being configured to circulate the gas flowing in the return line (6) from the first end (12) to the second end (13) in the first flow direction (14), and to circulate the gas flowing in the second supply circuit (8) from the second end (13) to the first end (12) in the second flow direction (15).

4. The supply system (1) according to claim 3, wherein: The return line (6) comprises a branch (16) configured to extend from the second end (13) of the common section (11) to the bottom of the tank (2).

5. The supply system (1) according to claim 4, wherein: The branch (16) comprises an ejector (17) which is configured to be arranged at the bottom of the tank (2).

6. The supply system (1) according to any one of claims 1 to 5, wherein: The heat exchanger (7) is a first heat exchanger (18), the supply system (1) comprises a cooling circuit (19) and a second heat exchanger (21), the cooling circuit (19) comprises a pumping device (20), the pumping device (20) is configured to pump the gas extracted from the tank (2) in a liquid state, and the second heat exchanger (21) is configured to achieve heat exchange between the vapor gas circulating in the return line (6) and the liquid gas circulating in the cooling circuit (19).

7. Supply system (1) according to the preceding claim, wherein: The first heat exchanger (18) is configured to cool the vapor gas flowing in the return line (6), and the second heat exchanger (21) is configured to liquefy the vapor gas flowing in the return line (6).

8. Supply system (1) according to claim 6 or 7, in combination with claim 3, wherein: The cooling circuit (19) and the return line (6) are joined together downstream of the second heat exchanger (21) and upstream of the first end (12) of the common section (11).

9. The supply system (1) according to any of the preceding claims, in combination with claim 4, comprises at least one control member (22, 22a, 22b, 22c, 22d), which is configured to control the air flow in the return line (6) and / or the second supply circuit (8) and / or the branch (16).

10. A floating structure for transporting and / or storing liquid gas, comprising at least one tank (2) configured to contain gas, at least one gas consuming appliance (3) and at least one supply system (1) according to any one of the preceding claims.

11. A method for supplying at least one gas consuming appliance (3, 3a, 3b) of a floating structure, the floating structure comprising at least one tank (2) configured to contain gas, implemented by a supply system (1) according to any one of claims 1 to 9, during which: - when the amount of vapor gas contained in the tank (2) is greater than the supply demand of the gas consuming device (3, 3a, 3b), the gas consuming device (3, 3a, 3b) is supplied by the vapor gas contained in the tank (2) via the first supply circuit (4), the excess vapor gas flows in the return line (6), and the excess gas flows in the common section (11) along the first flow direction (14), -When the amount of vapor gas contained in the tank (2) is less than the supply demand of the gas consuming device (3, 3a, 3b), the gas consuming device (3, 3a, 3b) is supplied with liquid gas contained in the tank (2) at least via the second supply circuit (8), and the liquid gas circulates in the common section (11) along a second flow direction (15) opposite to the first flow direction (14).

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