Gas supply system for at least one gas-consuming device of a floating structure

Abstract

Gas supply system for at least one gas consuming device of a floating structure The present invention relates to a gas supply system (1) for a gas consuming device (3, 3a, 3b), comprising: a first gas supply circuit (4) for the gas consuming device (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 consuming device (3, 3a, 3b), comprising an evaporation device (10) configured to vaporize the gas in the liquid state, characterized in that the return line (6) and the second supply circuit (8) share a common portion (11), the common portion (11) being arranged downstream of the heat exchanger (7) and upstream of the evaporation device (10). (figure 1)

Description

Title of the invention: Gas supply system for at least one gas-consuming device of a floating structure

[0001] The present invention relates to the field of floating structures for storing and / or transporting gas in the liquid state and more particularly concerns a gas supply system for at least one gas-consuming device included within such floating structures.

[0002] During a journey made by a ship comprising at least one tank of gas in the liquid state intended to be consumed and / or to be delivered to a destination point, said ship may be able to use at least a portion of said gas in the liquid state in order to supply at least one of its gas-consuming devices, and this via a gas supply system.

[0003] Generally speaking, it is known to favor the consumption of the gas that has evaporated within the tank in order to supply the gas-consuming device. Such evaporation can occur following an overall increase in the temperature of the tank over time and the gas in the vapor state generated must be evacuated in order to avoid overpressure in the tank. The gas supply to the gas-consuming device is carried out using the supply system mentioned above. The potential excess gas in the vapor state can return to the tank using a return line, but not without having been cooled beforehand.

[0004] When the gas in the vapor state is present in too small a quantity to meet the supply needs of the gas-consuming device, the supply system can also address this problem by taking gas in the liquid state from the tank and evaporating it before sending it to the gas-consuming device.

[0005] All these functionalities of such a supply system necessarily generate a significant quantity of materials, such as pipes, which necessarily results in significant spatial and mechanical bulk, especially if the floating structure is equipped with a plurality of tanks. Such bulk can prove problematic if one wishes to modify a supply system by adding functionalities, and therefore necessarily adding more materials. The lack of space can therefore prevent any potential improvement of certain supply systems.

[0006] The present invention makes it possible to circumvent this problem of spatial and mechanical bulk and as such proposes a system for supplying gas to at least one gas-consuming device of a floating structure comprising at least one tank configured to contain the gas, the supply system comprising: - at least one first gas supply circuit for the gas-consuming appliance comprising at least one compression device configured to compress gas taken in the vapor state from the tank to a pressure compatible with the needs of the gas-consuming appliance, - 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 carry out a heat exchange between the gas circulating in the first supply circuit and the gas circulating in the return line, - at least one second gas supply circuit for the gas-consuming device, comprising at least one pump configured to pump the gas taken in the liquid state from the tank and at least one evaporation device configured to vaporize the gas in the liquid state,

[0007] characterized in that the return line and the second power supply circuit share a common portion.

[0008] Thanks to the supply system according to the invention, it is possible to partially combine the return line and the second supply circuit in order to limit the number of pipes necessary for the design of said supply system. This may prove useful when adding an element within a supply system already partially installed within the floating structure. For example, the addition of the return line and the exchanger within a floating structure already comprising the first supply circuit and the second supply circuit is facilitated because part of the pipe used for the return line is already part of the second supply circuit. This avoids adding pipes further cluttering the space used by the supply system and simplifies the circuits.Another advantage is to reduce the number of line crossings through the tank and thus limit the risks of loss of tank tightness.

[0009] The first supply circuit makes it possible to take the gas in the vapor state forming in the tank and to use it as fuel for the gas-consuming device. Although the tank has properties ensuring thermal insulation, the gas in the vapor state forms naturally over time and must be treated in one way or another in order to limit the increase in pressure in the tank. The first supply circuit therefore makes it possible to use it as fuel for the gas-consuming device. The compression device, in addition to ensuring the suction of the gas in the vapor state out of the tank, makes it possible to raise the latter to a pressure compatible with the gas-consuming device, for example between 6 and 18 bars.

[0010] The gas-consuming device may, for example, be a motor providing propulsion for the floating structure or an electric generator supplying power to the structure. floating in electricity. It is also possible that the supply system is capable of supplying a plurality of gas-consuming appliances, in which case the first supply circuit is adapted accordingly in order to be able to supply each of them with gas in the vapor state.

[0011] The return line is connected to the first supply circuit downstream of the compression device and allows the circulation of the gas in the vapor state present in excess of the supply requirement of the gas consuming device. Instead of wasting this excess gas in the vapor state, it circulates in the return line so that it can return to the tank. The heat exchanger allows it to be cooled during its return, thanks to a heat exchange with the gas in the vapor state leaving the tank and circulating in the first supply circuit. The excess gas in the vapor state is therefore preserved by returning to the tank instead of being burned or released into the atmosphere.

[0012] The second supply circuit is used in the event of a lack of gas in the vapor state in the tank to meet the supply needs of the gas consuming device. The pump makes it possible to take the gas in the liquid state and raise it to a pressure compatible with the gas consuming device. The evaporation device makes it possible to evaporate the gas in the liquid state so that it can subsequently be consumed by the gas consuming device. The evaporation of the gas in the liquid state can be done for example by heat exchange with a third fluid, such as sea water.

[0013] The common portion is part of both the return line and the second supply circuit, in order to avoid multiplying the number of pipes in the supply system. Partially combining the return line and the second supply circuit is advantageous in the sense that the return line is used in the event of an excess of gas in the vapor state compared to the needs of the gas-consuming device, while the second supply circuit is used when the gas in the vapor state is present in too small a quantity or absent and therefore cannot meet the needs of the gas-consuming device alone. Thus, the return line and the second supply circuit are never used simultaneously. The implementation of a portion common to the return line and the second supply circuit is therefore entirely possible without harming the overall operation of the supply system.

[0014] According to an optional feature of the invention, the common portion is connected between the heat exchanger and the evaporation device. According to one example, the common portion is fluidically connected to the circuit downstream of the heat exchanger and upstream of the evaporation device, seen in the same direction of gas circulation.

[0015] According to a characteristic of the invention, the common portion is configured to circulate gas in a first direction of circulation or in a second direction of circulation opposite to the first direction of circulation. Indeed, when the gas circulates in the return line, it circulates towards the tank to return there, while when the gas circulates in the second supply circuit, it circulates from the tank to the gas-consuming appliance, in a direction of circulation opposite to that of the gas circulating in the return line.

[0016] According to a characteristic of the invention, the common portion comprises a first end and a second end from which the return line and the second supply circuit separate, the common portion being configured to circulate the gas circulating in the return line in the first direction of circulation going from the first end to the second end, and to circulate the gas circulating in the second supply circuit in the second direction of circulation going from the second end to the first end.

[0017] The first end and the second end delimit the common portion and each constitute a junction point between the return line and the second supply circuit. As described previously, the gas does not circulate in the same direction of circulation depending on whether it circulates in the return line or in the second supply circuit. The first end corresponds to the end of the common portion furthest from the tank while the second end corresponds to the end of the common portion closest to the tank. The gas therefore does not circulate from the same end to the same other end depending on whether it circulates in the return line or in the second supply circuit.

[0018] According to a characteristic of the invention, the return line comprises a branch configured to extend from the second end of the common portion to a bottom of the tank. The branch corresponds to the part of the return line extending between the common portion and the tank. This is independent of the second supply circuit so as not to damage the pump submerged in the tank and forming part of the second supply circuit.

[0019] The branch can advantageously be entirely positioned at the bottom of the tank or at least immersed within the tank. In terms of function, such a variant does not differ from a branch arranged at the heart of the pipes of the supply system. However, arranging the branch within the tank avoids arranging more pipes at the heart of the supply system, which helps to limit the spatial size of the supply system.

[0020] According to a characteristic of the invention, the branching comprises an ejector configured to be arranged at the bottom of the tank. This is a first embodiment lization of the supply system according to the invention. In this first embodiment, the ejector constitutes the last element of the return line before the gas circulating in the latter is returned to the tank. Indeed, although the heat exchanger cools the gas in the vapor state, such cooling is not sufficient to reliquefy the gas circulating in the return line. The ejector compensates for this by ensuring a mixture between the gas in the vapor state circulating in the return line and the gas in the liquid state at the bottom of the tank, so that the gas in the vapor state is released at the bottom of the tank in the liquid state. The ejector is advantageously placed as deep as possible in the tank because it is at the bottom of the tank that the temperature of the gas in the liquid state is the lowest.

[0021] According to a characteristic of the invention, the heat exchanger is a first heat exchanger, the supply system comprising a cooling circuit and a second heat exchanger, the cooling circuit comprising a pumping device configured to pump the gas taken in the liquid state from the tank, the second heat exchanger being configured to carry out a heat exchange between the gas in the vapor state circulating in the return line and the gas in the liquid state circulating in the cooling circuit. This is a second embodiment of the supply system according to the invention.

[0022] In this second embodiment, the gas in the vapor state is liquefied using two heat exchangers before returning to the tank. This embodiment guarantees a return to the tank directly in the liquid state of the gas circulating in the return line.

[0023] The cooling circuit allows the pumping of the gas in the liquid state into the tank, and allows the liquefaction of the gas in the vapor state by circulating in the second heat exchanger.

[0024] According to a characteristic of the invention, the first heat exchanger is configured to cool the gas in the vapor state circulating in the return line while the second heat exchanger is configured to liquefy the gas in the vapor state circulating in the return line. In other words, the gas in the vapor state initially circulates within the first heat exchanger to be precooled by heat exchange with the gas in the vapor state circulating in the first supply circuit, then circulates within the second heat exchanger to be condensed by heat exchange with the gas in the liquid state circulating in the cooling circuit. From the point of view of the circulation of the gas circulating in the return line, the second heat exchanger is therefore downstream of the first heat exchanger.

[0025] According to a characteristic of the invention, the cooling circuit and the return line join downstream of the second heat exchanger and upstream of the first end of the common portion. In other words, the reliquefied gas circulating in the return line and the gas in the liquid state circulating in the cooling circuit meet at the outlet of the second heat exchanger before traveling through the common portion and then returning to the tank. This configuration helps to limit the number of pipes within the supply system according to the invention.

[0026] According to a characteristic of the invention, the supply system comprises at least one control member configured to control the circulation of the gas within the return line and / or the second supply circuit and / or the branch. The control member ensures management of the circulation of the gas within the supply system, and this as a function of the activity of the supply system and therefore as a function of the direction of circulation of the gas within the common portion. Advantageously, the system comprises a plurality of control members in order to improve the management of the circulation of the gas within the supply system.

[0027] The control member may for example be a valve or any other element configured to allow or prohibit the circulation of gas within a particular section. According to another non-exhaustive example, the control member may be a non-return valve or any other element allowing the circulation of gas in one direction of circulation but prohibiting the circulation of gas in the opposite direction of circulation.

[0028] The invention also covers a floating structure for the transport and / or storage of gas in the liquid state, comprising at least one tank configured to contain the gas, at least one gas-consuming device and at least one supply system as described previously.

[0029] The invention also covers a method for supplying at least one gas-consuming device of a floating structure comprising at least one tank configured to contain the gas, implemented by a supply system as described previously, during which: - when a quantity of gas in the vapor state contained in the tank is greater than a supply requirement of the gas consuming device, the gas consuming device is supplied via the first supply circuit from the gas in the vapor state contained in the tank, an excess of gas in the vapor state circulating in the return line, the excess gas circulating in the common portion in a first direction of circulation, - when a quantity of gas in the vapor state contained in the tank is less than the supply requirement of the gas consuming device, the gas consuming device is supplied at least via the second supply circuit from the gas in the liquid state contained in the tank, the gas in the liquid state circulating in the common portion in a second direction of circulation opposite to the first direction of circulation.

[0030] The sequence of the supply process, and therefore the direction of circulation of the gas within the common portion, is dependent on the quantity of gas in the vapor state present in the tank and the supply requirement of the gas-consuming device. It is possible for the supply system to be configured to supply gas to several gas-consuming devices, in which case the supply requirement of all the gas-consuming devices must be taken into account.

[0031] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several exemplary embodiments given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0032] [Fig. 1] is a schematic representation of a first embodiment of a supply system according to the invention arranged within a floating structure provided with at least one gas-consuming device,

[0033] [Fig.2] is a diagram of the circulation of a gas within the first embodiment of the supply system when gas in the vapor state is available in excess quantity compared to the supply requirement of the gas consuming device,

[0034] [Fig.3] is a diagram of gas circulation within the first embodiment of the supply system when gas in the vapor state is available in too small a quantity compared to the supply requirement of the gas-consuming device,

[0035] [Fig.4] is a schematic representation of a second embodiment of the power supply system according to the invention,

[0036] [Fig.5] is a diagram of gas circulation within the second embodiment of the supply system when gas in the vapor state is available in excess of the supply requirement of the gas-consuming device,

[0037] [Fig.6] is a diagram of gas circulation within the second embodiment of the supply system when gas in the vapor state is available in too small a quantity compared to the supply requirement of the gas-consuming device,

[0038] [Fig.7] is a schematic representation of the first embodiment of the supply system according to the invention, suitable for a floating structure comprising two tanks configured to contain the gas.

[0039] [Fig.l] is a schematic representation of a first embodiment of a gas supply system 1 according to the invention. Such a supply system 1 may for example be integrated into a floating structure for transporting and / or storing gas in the liquid state, said gas being for example natural gas, also called LNG. Such a floating structure comprises at least one tank 2 ensuring the transport and / or storage of the gas in the liquid state and at least one gas-consuming device 3, which may for example be a motor ensuring the propulsion of the floating structure or an electric generator ensuring the power supply of the floating structure in electricity.

[0040] The tank 2 is configured to ensure sealing and thermal insulation with respect to the gas in the liquid state that it contains. However, over time, the gas in the liquid state present in the tank 2 partially evaporates, leading to an increase in the saturation pressure of the tank 2. The supply system 1 therefore makes it possible to prevent a potential overpressure within the tank 2 by evacuating the gas in the vapor state therefrom.

[0041] To do this, the supply system 1 comprises a first supply circuit 4 extending between the tank 2 and the gas-consuming device 3. The first supply circuit 4 comprises a compression device 5 configured to suck in the gas in the vapor state present in the tank 2. In addition, the compression device 5 is also configured to raise the pressure of the gas in the vapor state so that the latter has a pressure compatible with the needs of the gas-consuming device 3. The first supply circuit 4 thus makes it possible, on the one hand, to regulate the saturation pressure of the tank 2 and, on the other hand, to supply fuel to the gas-consuming device 3, the latter of course having to be compatible with the nature of the gas contained in the tank 2.

[0042] The supply system 1 also comprises a return line 6 connected to the first supply circuit 4 downstream of the compression device 5 and extending to the tank 2. The return line 6 is used in the event of excess gas in the vapor state compared to the supply requirements of the gas-consuming device 3. The excess gas is then returned to the tank 2 via the return line 6, not without having been previously cooled.

[0043] In this respect, the supply system 1 comprises a heat exchanger 7 configured to operate a heat exchanger between the gas in the vapor state circulating in the first supply circuit 4 and the gas in the vapor state circulating in the return line 6 and thus to cool the latter before its return to the tank 2.

[0044] The supply system 1 further comprises a second supply circuit 8 which is used when the gas in the vapor state is present in too small a quantity to cover the supply needs of the gas-consuming appliance 3. The second supply circuit 8 can therefore be used in combination with the first supply circuit 4 or alone in the event of a total absence of gas in the vapor state in the tank 2.

[0045] The second supply circuit 8 comprises a pump 9 arranged at the bottom of the tank 2 and allowing the collection of gas in the liquid state in the tank 2. The supply system 1 further comprises an evaporation device 10 ensuring the evaporation of the gas in the liquid state circulating in the second supply circuit 8, and this before supplying the gas-consuming device 3, the latter only tolerating gas in the vapor state for its supply. Evaporation can, for example, be done by heat exchange with a third fluid, such as seawater.

[0046] Such a supply system 1 thus comprises several supply means as well as a cooling means before a return to tank 2. All of these means therefore require a significant number of pipes and this can lead to a problem of mechanical congestion, for example during an installation of a section of the supply system to complete the latter within a given floating structure.

[0047] The supply system 1 according to the invention solves this problem of mechanical bulk by bringing together a part of the return line 6 and a part of the second supply circuit 8 in a common portion 11. In other words, the common portion 11 is part of both the return line 6 and the second supply circuit 8, thus making it possible to limit the number of pipes necessary for the proper functioning of the supply system 1. More particularly, the common portion 11 is arranged downstream of the heat exchanger 7 from the point of view of the return line 6, and upstream of the evaporation device 10 from the point of view of the second supply circuit 8, the downstream and upstream character being compared according to the same direction of circulation.

[0048] By way of example, during an installation of the return line 6 and the heat exchanger 7 within a floating structure already equipped with the first supply circuit 4 and the second supply circuit 8, it is possible to partially use the pipe of the second supply circuit 8 to form the common portion 11 during the implementation of the return line 6 and thus to limit the number of pipes within the supply system 1. This therefore allows cost savings and a limitation of the mechanical size.

[0049] The bringing together of the return line 6 and the second supply circuit 8 is particularly advantageous, in the sense that they are never used simultaneously. Indeed, the return line 6 is used in the event of an excess of gas in the vapor state in the tank 2 while the second supply circuit 8 is used in the event of a lack or absence of gas in the vapor state in the tank 2. The return line 6 and the second supply circuit 8 can therefore be brought together in the common portion 11 without this generating interference in their respective operation.

[0050] It is thus understood that the common portion 11 is configured to ensure the circulation of the gas in two directions of circulation depending on the activity of the return line 6, ensuring the circulation of the gas towards the tank 2, or the activity of the second supply circuit 8, ensuring the circulation of the gas from the tank 2. As such, the common portion 11 comprises a first end 12 and a second end 13, corresponding to the delimitations of the common portion 11, from from which the return line 6 and the second supply circuit 8 are separated from each other.

[0051] By way of example, as illustrated in [Fig.l] and in the following figures, the first end 12 corresponds to the end of the distal common portion 11 of the tank 2, while the second end 13 corresponds to the end of the proximal common portion 11 of the tank 2. The gas can therefore circulate in a first circulation direction 14 going from the first end 12 to the second end 13, or in a second circulation direction 15 going from the second end 13 to the first end 12. Thus, the gas circulates in the common portion 11 in the first circulation direction 14 when said gas circulates in the return line 6, and the gas circulates in the common portion 11 in the second circulation direction 15 when said gas circulates in the second supply circuit 8.

[0052] In order to further control the circulation of the gas within in particular the common portion 11, the supply system 1 comprises at least one control member 22 authorizing or prohibiting the circulation of the gas at the level of the circuit or the line on which said control member 22 is arranged.

[0053] According to the example illustrated in [Fig.l], the supply system 1 comprises a plurality of control members 22. More particularly, 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 portion 11 and a second control member 22b arranged on the second supply circuit 8 between the first end 12 of the common portion 11 and the evaporation device 10. According to an example illustrated in FIGS. 1 to 3, the first control member 22a and the second control member 22b are valves that can be opened or closed depending on the circulation of the gas and the objective of this circulation.

[0054] The return line 6 includes a branch 16 extending between the second end 13 of the common portion 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. As such, the branch 16 may also include a third control member 22c which is also in the form of a valve and is able to pivot between an open or closed position depending on the gas circulation and the purpose of this circulation.

[0055] According to the first embodiment of the feed system 1, the branch 16 extends to the tank 2 and comprises an ejector 17 immersed at the bottom of the tank 2. The ejector 17 ensures a mixture between the gas in the vapor state circulating in the return line 6 and the gas in the liquid state at the bottom of the tank 2, so that the gas in the vapor state is released at the bottom of the tank 2 in the liquid state. This configuration can lead to an increase in the overall temperature of the gas in the liquid state contained in the tank 2. To compensate for this, refrigeration means not shown can compensate for this increase in temperature by cooling the gas in the liquid state of tank 2.

[0056] In addition, the second supply circuit 8 comprises a fourth control member 22d arranged between the pump 9 and the second end 13 of the common portion 11. The fourth control member 22d is in the form of a non-return valve preventing the circulation of gas in a direction of circulation going from the second end 13 of the common portion 11 towards the pump 9, thus optimizing the circulation of the gas coming from the return line 6 and forcing it to circulate within the branch 16.

[0057] Figures 2 and 3 represent the circulation of gas in the first embodiment of the supply system 1, respectively when the gas in the vapor state present in the tank 2 is present in excess compared to the needs of the gas-consuming device 3 and when there is too little or no gas in the vapor state in the tank 2 to sufficiently supply it. In [Fig.2], the first control member 22a and the third control member 22c authorize the circulation of gas while the second control member 22b prohibits the circulation of gas. Conversely, in [Fig.3], the first control member 22a and the third control member 22c prohibit the circulation of gas while the second control member 22b authorizes the circulation of gas.

[0058] For figures 2 and 3, the portions of the supply system 1 through which gas in the liquid or vapor state flows are represented by solid lines, while the portions of the supply system 1 without gas circulation are represented by dotted lines.

[0059] [Fig. 2] is an example of gas circulation where the gas in the vapor state is present in excess in the tank 2. The gas in the vapor state is therefore sucked in by the compression device 5 and circulates in the first supply circuit 4. Initially, the gas in the vapor state passes through the heat exchanger 7 in order to cool the gas in the vapor state circulating in the return line 6. At the outlet of the heat exchanger 7, the gas in the vapor state circulating in the first supply circuit 4 is then compressed by the compression device 5 to a pressure compatible with the needs of the gas-consuming appliance 3.

[0060] The gas in the vapor state then circulates to the gas consuming device 3 to supply the latter. The quantity of gas in the vapor state supplied to the gas consuming device 3 is dependent on the supply requirements of the latter. The excess gas in the vapor state circulates in the return line 6 at the outlet of the compression device 5. [Fig. 2] illustrates a circulation of gas in the vapor state to the gas consuming device 3, but it is also possible that the gas consuming device 3 has no need for a supply of gas in the vapor state, in which case all of the gas in the vapor state compressed by the compression device 5 circulates within the return line 6 thereafter.

[0061] The gas in the vapor state circulating in the return line 6 passes through the heat exchanger 7. As the gas in the vapor state circulating in the return line 6 has been previously compressed by the compression device 5, said gas is at a higher temperature than the gas in the vapor state leaving the tank 2 and circulating in the first supply circuit 4. The gas in the vapor state circulating in the return line 6 is therefore cooled by passing through the heat exchanger 7.

[0062] The gas in the vapor state continues its circulation until it reaches the first end 12 of the common portion 11 before circulating in the latter in the first direction of circulation 14 to the second end 13. The gas in the vapor state then circulates within the branch 16 and is ejected to the bottom of the tank 2 by the ejector 17.

[0063] [Fig.3] represents the opposite configuration to [Fig.2], that is to say that the gas at the vapor state is present in too small a quantity, or even absent, to meet the power supply needs of the gas-consuming device 3.

[0064] If gas in the vapor state is present in the tank 2, it circulates in the first supply circuit 4, then passes through the heat exchanger 7 without consequence or bypasses the latter by circulating within a bypass line not shown. The gas in the vapor state is then compressed by the compression device 5 and continues its circulation in the first supply circuit 4 until it supplies the gas-consuming device 3. Since there is no excess gas in the vapor state, there is no circulation of gas within the return line 6. If there is no gas in the vapor state present in the tank 2, then there is no circulation of gas in the first supply circuit 4.

[0065] In this configuration, the lack of gas in the vapor state to meet the needs of the gas-consuming device 3 is therefore compensated using the second supply circuit 8. To do this, the pump 9 takes the gas present in the liquid state in the tank 2. The gas in the liquid state circulates to the second end 13 of the common portion 11 before circulating in the latter in the second direction of circulation 15 to the first end 12.

[0066] The gas in the liquid state then continues its circulation in the second supply circuit 8 until it is evaporated within the evaporation device 10. At the outlet of the latter, the evaporated gas circulates in the second supply circuit 8 until it supplies the gas-consuming device 3.

[0067] [Fig.4] represents a second embodiment of the power supply system 1 according to the invention. The second embodiment differs from the first embodiment in particular in that the gas in vapor state circulating in the return line 6 is reliquefied before returning to the tank 2.

[0068] For this, the heat exchanger 7 shown in FIGS. 1 to 3 for the first embodiment is here a first heat exchanger 18, still configured to carry out a heat exchange between the gas in the vapor state circulating in the first supply circuit 4 and the gas in the vapor state circulating in the return line 6.

[0069] The second embodiment of the supply system 1 further comprises a cooling circuit 19 comprising a pumping device 20 configured to take gas in the liquid state from the tank 2. Finally, the second embodiment of the supply system 1 comprises a second heat exchanger 21 configured to carry out a heat exchange between the gas in the vapor state circulating in the return line 6 and the gas in the liquid state circulating in the cooling circuit 19. It is therefore within this second heat exchanger 21 that the gas in the vapor state circulating in the return line is reliquefied before returning to the tank 2.

[0070] At the outlet of the second heat exchanger 21, the reliquefied gas circulating in the return line 6 and the gas in the liquid state circulating in the cooling circuit 19 meet upstream of the first end 12 of the common portion 11 before circulating to the tank 2. As the gas is entirely reliquefied, the second embodiment of the supply system 1 does not include an ejector at the branch 16, but an orifice opening out at the bottom of the tank 2.

[0071] It is thus understood that the gas in the vapor state circulating in the return line 6 is initially cooled within the first heat exchanger 18, then is liquefied within the second heat exchanger 21.

[0072] Another difference between the illustrations of the two embodiments of the supply system 1 according to the invention is that the supply system 1 illustrated in [Fig. 4] is configured to supply gas to a first gas-consuming device 3a and a second gas-consuming device 3b. As cited as an example previously, the first gas-consuming device 3a may be an engine providing propulsion for the floating structure while the second gas-consuming device 3b may be an electric generator providing electricity to the floating structure. Advantageously, the first gas-consuming device 3a and the second gas-consuming device 3b have the same compatibilities in terms of the gas pressure supplying them, i.e. the pressure applied to the gas by the compression device 5 or by the pump 9.

[0073] The first supply circuit 4 and the second supply circuit 8 are therefore 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. Such a configuration is however not specific to the second embodiment and it is therefore possible to supply two or more gas-consuming appliances 3a, 3b using the first embodiment of the supply system 1, or to supply a single gas-consuming appliance 3 using the second embodiment of the supply system 1.

[0074] 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 this time in the form of non-return valves. The non-return valves allow the circulation of gas in one direction of circulation, but not in the opposite direction of circulation, which guarantees an operation similar to that of the valves illustrated in FIGS. 1 to 3. The type of control member 22 is however indifferent to the embodiment and it is therefore possible to implement valves or non-return valves independently of the embodiment. The third control member 22c and the fourth control member 22d are always respectively a valve and a non-return valve.

[0075] The structural and functional elements not described for this second embodiment of the power supply system 1 being identical to those of the first embodiment, reference will be made to the description of [Fig.l] concerning the elements common to the two embodiments.

[0076] Figures 5 and 6 represent the circulation of the gas in the second embodiment of the supply system 1, respectively when the gas in the vapor state present in the tank 2 is present in excess compared to the needs of the gas-consuming device(s) 3a, 3b and when there is too little or no gas in the vapor state in the tank 2 to sufficiently supply the latter.

[0077] Just as for figures 2 and 3, for figures 5 and 6 the portions of the supply system 1 traversed by gas in the liquid or vapor state are represented by solid lines, while the portions of the supply system 1 without gas circulation are represented by dotted lines.

[0078] [Fig. 5] is an example of gas circulation where the gas in the vapor state is present in excess in the tank 2. The gas in the vapor state is therefore sucked in by the compression device 5 and circulates in the first supply circuit 4. Initially, the gas in the vapor state passes through the heat exchanger 7 in order to cool the gas in the vapor state circulating in the return line 6. At the outlet of the heat exchanger 7, the gas in the vapor state circulating in the first supply circuit 4 is then compressed by the compression device 5 to a pressure compatible with the needs of the gas-consuming appliances 3a, 3b.

[0079] The gas in the vapor state then circulates to the first gas-consuming device 3a and / or to the second gas-consuming device 3b to supply the latter. Depending on the need, the first supply circuit 4 can supply only one of the two gas-consuming devices 3a, 3b or both simultaneously. Such a configuration can be regulated by a system of non-re- presented.

[0080] The excess gas in the vapor state circulates in the return line 6 at the outlet of the compression device 5. [Fig. 5] illustrates a circulation of gas in the vapor state to the gas consuming devices 3a, 3b, but it is also possible that the gas consuming devices 3 have no need for a supply of gas in the vapor state, in which case all of the gas in the vapor state compressed by the compression device 5 circulates within the return line 6 thereafter.

[0081] The gas in the vapor state circulating in the return line 6 passes through the heat exchanger 7. As the gas in the vapor state circulating in the return line 6 has been previously compressed by the compression device 5, said gas is at a higher temperature than the gas in the vapor state leaving the tank 2 and circulating in the first supply circuit 4. The gas in the vapor state circulating in the return line 6 is therefore cooled by passing through the heat exchanger 7.

[0082] The gas in the vapor state thus cooled then circulates within the second heat exchanger 21. In parallel, gas in the liquid state circulates within the cooling circuit 19 thanks to the pumping device 20 and also circulates within the second heat exchanger 21 in order to liquefy the gas in the vapor state previously cooled.

[0083] At the outlet of the second heat exchanger 21, the reliquefied gas and the gas in the liquid state circulating in the cooling circuit 19 join and continue their circulation until reaching the first end 12 of the common portion 11 before circulating in the latter in the first direction of circulation 14 to the second end 13. The mixture of reliquefied gas and gas in the liquid state coming from the cooling circuit 19 then circulates within the branch 16 to the bottom of the tank 2.

[0084] [Fig.6] represents the opposite configuration to [Fig.5], that is to say that the gas in the vapor state is present in too small a quantity, or even absent, to meet the supply needs of one or both gas-consuming devices 3a, 3b.

[0085] If gas in the vapor state is present in the tank 2, it circulates in the first supply circuit 4, then passes through the heat exchanger 7 without consequence or else bypasses the latter by circulating within a bypass line not shown. The gas in the vapor state is then compressed by the compression device 5 and continues its circulation in the first supply circuit 4 until it supplies one or both of the gas-consuming devices 3a, 3b. Since there is no excess gas in the vapor state, there is no circulation of gas within the return line 6. Therefore, in the absence of gas in the vapor state to be reliquefied, there is also no circulation of gas in the liquid state within the cooling circuit 19. If there is no gas in the vapor state present in the tank 2, then there is no circulation of gas in the first supply circuit 4.

[0086] In this configuration, the lack of gas in the vapor state to meet the needs of one or both gas-consuming devices 3a, 3b is therefore compensated using the second supply circuit 8. To do this, the pump 9 takes the gas present in the liquid state in the tank 2. The gas in the liquid state circulates to the second end 13 of the common portion 11 before circulating in the latter in the second direction of circulation 15 to the first end 12.

[0087] The gas in the liquid state then continues its circulation in the second supply circuit 8 until it is evaporated within the evaporation device 10. At the outlet of the latter, the evaporated gas circulates in the second supply circuit 8 until it supplies the first gas-consuming device 3a and / or the second gas-consuming device 3b.

[0088] [Fig. 7] represents a variant of the first embodiment of the supply system 1 according to the invention. This variant consists of an application of the supply system 1 to a floating structure comprising a plurality of tanks 2a, 2b. In [Fig. 7], a first tank 2a and a second tank 2b are illustrated, but the supply system 1 is applicable for a floating structure comprising more tanks.

[0089] The first supply circuit 4 is thus fluidically linked to each of the tanks 2a, 2b, allowing the compression device 5 to suck in the gas in the vapor state present in the two tanks 2a, 2b.

[0090] The return line 6 is also fluidically connected to the two tanks 2a, 2b, each of which interacts with its own branch 16a, 16b, both connected to the common portion 11, as well as its own ejector 17a, 17b. In other words, there are as many branches 16a, 16b and ejectors 17a, 17b as there are tanks 2a, 2b.

[0091] [Fig.7] illustrates a variant concerning the branch 16b interacting with the second tank 2b. The branch 16b is in fact configured to be immersed within the second tank 2b, unlike the branch 16a which overhangs the first tank 2a just as was illustrated previously. The variant of positioning of the branch 16b makes it possible to use the internal volume of the second tank 2b in order to integrate said branch 16b and thus to avoid further cluttering the space dedicated to the supply system 1 by the pipes of the branch 16b. It should be noted that this variant is also applicable to the second embodiment described previously.

[0092] Finally, concerning the second supply circuit 8, this is also fluidically linked to the two tanks 2a, 2b, each of them interacting with its own pump 9a, 9b, both connected to the common portion 11.

[0093] As illustrated in [Fig.7], the power supply system 1 does not comprise always only one common portion 11 despite the presence of two tanks 2a, 2b. It is thus understood that the interest of the supply system 1 according to the invention is significant when the floating structure comprises a plurality of tanks, because the more tanks there are, the more pipes there are. The fact of implementing a common portion 11 to the return line 6 and to the second supply circuit 8 can therefore greatly reduce the mechanical size of the supply system 1 when several tanks are present within the floating structure.

[0094] The different gas circulations detailed in Figures 2 and 3 are also applicable to [Fig.7]. The gas can be taken from or returned to one and / or the other of the tanks 2a, 2b depending on different parameters such as the volume of the tanks 2a, 2b, the quantity of gas present in each of the tanks 2a, 2b or the temperature thereof.

[0095] It is furthermore obvious that the second embodiment of the supply system 1 according to the invention is also applicable for a floating structure comprising a plurality of tanks 2a, 2b.

[0096] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

[0097] The invention, as just described, achieves the aim it set itself, and makes it possible to propose a gas supply system for at least one gas-consuming device of a floating structure, said supply system guaranteeing the limitation of the number of pipes necessary for its proper operation. Variants not described here could be implemented without departing from the context of the invention, provided that, in accordance with the invention, they comprise a supply system in accordance with the invention.

Claims

Claims

1. A gas supply system (1) for at least one gas-consuming device (3, 3a, 3b) of a floating structure comprising at least one tank (2) configured to contain the gas, the supply system (1) comprising: - at least one first gas supply circuit (4) for the gas-consuming device (3, 3a, 3b) comprising at least one compression device (5) configured to compress gas taken in the vapor state from the tank (2) to a pressure compatible with the needs of the gas-consuming device (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 carry out a heat exchange between the gas circulating in the first supply circuit (4) and the gas flowing in the return line (6),- at least one second gas supply circuit (8) for the gas-consuming device (3, 3a, 3b), comprising at least one pump (9) configured to pump the gas taken in the liquid state from the tank (2) and at least one evaporation device (10) configured to vaporize the gas in the liquid state, characterized in that the return line (6) and the second supply circuit (8) share a common portion (11).,

2. A power supply system (1) according to claim 1, wherein the common portion (11) is connected between the heat exchanger (7) and the evaporation device (10).

3. A supply system (1) according to any one of claims 1 or 2, wherein the common portion (11) is configured to circulate gas in a first circulation direction (14) or in a second circulation direction (15) opposite to the first circulation direction (14).

4. A power supply system (1) according to claim 3, wherein the common portion (11) comprises a first end (12) and a second end (13) from which the return line (6) and the second supply circuit (8) separate, the common portion (11) being configured to circulate the gas flowing in the return line (6) in the first circulation direction (14) going from the first end (12) to the second end (13), and to circulate the gas flowing in the second supply circuit (8) in the second circulation direction (15) going from the second end (13) to the first end (12).

5. A feed system (1) according to claim 4, wherein the return line (6) comprises a branch (16) configured to extend from the second end (13) of the common portion (11) to a bottom of the tank (2).

6. Feeding system (1) according to claim 5, wherein the branch (16) comprises an ejector (17) configured to be arranged at the bottom of the tank (2).

7. A feed system (1) according to any one of claims 1 to 6, wherein the heat exchanger (7) is a first heat exchanger (18), the feed system (1) comprising a cooling circuit (19) and a second heat exchanger (21), the cooling circuit (19) comprising a pumping device (20) configured to pump the gas taken in the liquid state from the tank (2), the second heat exchanger (21) being configured to carry out a heat exchange between the gas in the vapor state circulating in the return line (6) and the gas in the liquid state circulating in the cooling circuit (19).

8. A supply system (1) according to the preceding claim, wherein the first heat exchanger (18) is configured to cool the gas in the vapor state circulating in the return line (6) while the second heat exchanger (21) is configured to liquefy the gas in the vapor state circulating in the return line (6).

9. A supply system (1) according to claim 7 or 8, in combination with claim 4, wherein the cooling circuit (19) and the return line (6) join downstream of the second heat exchanger (21) and upstream of the first end (12) of the common portion (11).

10. A power supply system (1) according to any preceding claim, in combination with claim 5, comprising at least at least one control member (22, 22a, 22b, 22c, 22d) configured to control the circulation of the gas within the return line (6) and / or the second supply circuit (8) and / or the branch (16).

11. Floating structure for the transport and / or storage of gas in the liquid state, comprising at least one tank (2) configured to contain the gas, at least one gas-consuming device (3) and at least one supply system (1) according to any one of the preceding claims.

12. Method for supplying at least one gas-consuming device (3, 3a, 3b) of a floating structure comprising at least one tank (2) configured to contain the gas, implemented by a supply system (1) according to any one of claims 1 to 10, during which: - when a quantity of gas in the vapor state contained in the tank (2) is greater than a supply requirement of the gas consuming device (3, 3a, 3b), the gas consuming device (3, 3a, 3b) is supplied via the first supply circuit (4) from the gas in the vapor state contained in the tank (2), an excess of gas in the vapor state circulating in the return line (6), the excess gas circulating in the common portion (11) in a first circulation direction (14), - when a quantity of gas in the vapor state contained in the tank (2) is less than the supply requirement of the gas consuming device (3, 3a, 3b), the gas consuming device (3, 3a, 3b) is supplied at least via the second supply circuit (8) from the gas in the liquid state contained in the tank (2), the gas in the liquid state circulating in the common portion (11) in a second direction of circulation (15) opposite to the first direction of circulation (14).

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