Gas supply system for a gas-consuming appliance on a floating structure

Abstract

Gas supply system for a gas-consuming appliance on a floating structure. The present invention relates to a supply system (1) comprising: a first supply circuit (4) including a pumping device (8) and an evaporator (9), a second supply circuit (5) including a compressor (10), characterized in that the supply system (1) comprises a connecting line (12) and a siphon line (15), the connecting line (12) extending between a first junction point (13) located on the first supply circuit (4) and a second junction point (14) located on the second supply circuit (5), the siphon line (15) being connected to the first supply circuit (4), the compressor (10) being capable of drawing the gas in liquid form from the tank (2) via the siphon line (15) and the connecting line (12). (Figure 1)

Description

Title of the invention: Gas supply system for a gas-consuming appliance on a floating structure

[0001] The present invention relates to the field of floating structures for the transport and / or storage of gas in liquid state and relates more particularly to a gas supply system for at least one consuming device included within such floating structures, as well as a method for controlling such a system.

[0002] During a journey undertaken by a floating structure comprising a tank of gas in liquid form intended for consumption, said floating structure may be capable of using at least a portion of said gas in liquid form to supply at least one gas-consuming appliance, via a gas supply system.

[0003] Thus, it is known to draw the gas in vapor form that has formed naturally in the tank, compress it, and then circulate it to the gas-consuming appliance to supply it. It is also known that, in the event of an insufficient quantity of gas in vapor form within the tank, the gas in liquid form can be pumped directly into the tank and circulated first through an evaporation device to evaporate the gas into liquid form, since the gas-consuming appliance can only be supplied with gas in vapor form, and then supplied as fuel to the gas-consuming appliance.

[0004] To pump gas in its liquid state, it is known to install a submerged pumping device at the bottom of the tank. Over time, the volume of liquid gas within the tank can decrease significantly. This can eventually lead to the pumping device becoming exposed, which may then lose its prime or, more generally, be unable to pump the liquid gas. Such an event can also occur even if the pumping device is theoretically submerged, for example, in the event of significant rolling that could temporarily expose the pumping device. The latter can thus be damaged, and the gas supply to the floating structure may no longer be guaranteed.

[0005] The present invention falls within this context and, as such, proposes a gas supply system for at least one gas-consuming appliance of a floating structure comprising at least one tank configured to contain the gas, the supply system comprising: - at least one first supply circuit configured to supply gas to the gas-consuming appliance, the first supply circuit including at least one pumping device configured to, in a first supply mode, draw the gas in liquid state from the tank and at least an evaporation device configured to evaporate the gas into a liquid state circulating in the first supply circuit, - at least one second supply circuit configured to supply gas to the gas-consuming appliance, the second supply circuit comprising at least one compression device configured to, in the first supply mode, draw gas in vapor form from the tank and compress it to a pressure compatible with the needs of the gas-consuming appliance,

[0006] characterized in that the supply system comprises at least one junction line and at least one siphon line, the junction line extending between a first junction point disposed on the first supply circuit between the evaporator and the gas-consuming device and a second junction point disposed on the second supply circuit between the tank and the compression device, the siphon line being connected to the first supply circuit between the pumping device and the evaporator and comprising an end configured to be immersed in the tank, the compression device being capable of, in a second supply mode, drawing the gas in liquid form from the tank via the siphon line and the junction line.

[0007] The supply system according to the invention thus makes it possible to use the gas in its liquid state as fuel for the gas-consuming appliance, without using the pumping device. The latter is therefore not damaged by loss of prime due to a lack of liquid gas in the tank or excessive rolling. The supply system according to the invention also makes it possible to use a larger quantity of liquid gas as fuel for a tank of the same capacity.

[0008] The supply system is adapted for a floating structure capable of storing gas in liquid form for consumption by the gas-consuming appliance. The tank therefore empties as the floating structure travels.

[0009] The gas-consuming device may, for example, be a motor providing propulsion for the floating structure, or an electric generator supplying electricity to the floating structure. Furthermore, the power supply system may be configured to supply several gas-consuming devices simultaneously or alternately. An electric generator is understood to mean various types of means, such as a fuel cell or a gas boiler, consuming gas at low pressure between 1 and 4 bar relative.

[0010] The first supply circuit and the second supply circuit allow the gas-consuming appliance to be supplied with gas according to normal operation of the supply system, that is to say, either by pumping the gas in a liquid state and evaporating it before supplying it to the gas-consuming appliance for the first The supply circuit works by drawing in and compressing the vaporized gas contained in the tank headspace. Vaporized gas can form in the headspace following partial evaporation of liquid gas. Depending on the presence or absence of significant vaporized gas, either supply circuit can be used independently. Both supply circuits can also be used simultaneously.

[0011] The gas-consuming appliance is only suitable for consuming gas in a vapor state at a compatible pressure. Thus, when gas in a liquid state is intended to supply the gas-consuming appliance, it is first evaporated before being supplied to said appliance. The pumping device and the compression device respectively raise the gas in a liquid state and the gas in a vapor state to a pressure compatible with the requirements of the gas-consuming appliance.

[0012] In addition to these standard operating modes, the invention allows for efficient supply of the gas-consuming device(s), regardless of the time of the journey and / or navigation conditions, in particular through the joint implementation of a siphon line and a connecting line.

[0013] The connecting line extends from the first junction point to the second junction point in order to fluidly connect the first feed circuit downstream of the evaporator (with respect to the direction of gas flow) to the second feed circuit upstream of the compressor (with respect to the direction of gas flow). Thus, the evaporated gas flowing in the first feed circuit can flow to the second feed circuit to be compressed by the compressor.

[0014] The siphon line allows the tank to be connected to the first supply circuit in parallel with the pumping device. The end of the siphon line is immersed in the tank, advantageously at the bottom of the tank, for example a maximum of 2m from the bottom of the tank, and extends until it is connected to the first supply circuit, upstream of the evaporation device with respect to the direction of gas flow.

[0015] The siphon line and the connecting line are thus used in the second supply mode, which is used when there is a risk of the pumping device malfunctioning, for example, losing prime due to the emergence of liquid gas above the surface or due to rolling. When the gas is able to flow in the siphon line and the connecting line, the compression device is active and creates a vacuum upstream of it. This generates a pressure differential that forces the gas into a liquid state. to circulate within the siphon line, without the need to use a pumping device.

[0016] Thus, the supply system according to the invention can always supply the gas-consuming device, including when the pumping device is not operational and without risk of damaging the latter.

[0017] According to one feature of the invention, the supply system comprises a return line connected to the second supply circuit between the compressor and the gas-consuming appliance and configured to extend to the tank. The return line is capable of returning at least a portion of the gas in vapor form, compressed by the compressor, to the tank. Advantageously, the return line ensures the return of at least a portion of the gas in vapor form to the tank head. This has the effect of increasing the internal pressure within the tank and thus facilitates the circulation of the gas in liquid form in the siphon line, through an appropriate pressure differential within the loop formed by at least the tank, the siphon line, the connecting line, and the return line.It is therefore understood that this return line can be used if it is necessary to supply the gas-consuming appliance with the help of the siphon line and the junction line.

[0018] According to one feature of the invention, the compression device is a first compression device, the supply system comprising an auxiliary line and a second compression device disposed on the auxiliary line, said auxiliary line extending between the second junction point and a convergence point disposed on the second supply circuit between the first compression device and the gas-consuming appliance. In other words, the first compression device and the second compression device are arranged in parallel with respect to each other. Arranging two compression devices in parallel ensures redundancy between them, so that there is always a functional compression device, even in the event of a failure of one of the compression devices.Furthermore, it is possible to implement both compression devices simultaneously, in order to generate a pressure differential more easily and thus promote the circulation of gas in a liquid state within the siphon line.

[0019] The auxiliary line starts at the second junction point so that the two compression devices can be implemented in such a way as to ensure the same functions.

[0020] According to one feature of the invention, the convergence point is located on the second supply circuit between the first compression circuit and the connection to the return line. In the case where the supply system is Equipped with a return line, the convergence point is positioned upstream of the return line relative to the direction of gas flow. This allows the gas to flow through the return line, regardless of the compression device used.

[0021] According to one feature of the invention, the first supply circuit comprises a first control element disposed between the pumping device and the connection to the siphon line, and a second control element disposed between the first junction point and the gas-consuming appliance. The first and second control elements manage the gas flow within the first supply circuit. The first control element manages a fluid connection between the pumping device and the connection to the siphon line, while the second control element manages a fluid connection between the first junction point and the gas-consuming appliance.

[0022] According to one feature of the invention, the second supply circuit includes a control element disposed between the tank and the second junction point. The control element manages the gas flow within the second supply circuit. The control element manages a fluid connection between the tank and the second junction point.

[0023] According to one feature of the invention, the siphon line and the connecting line comprise, respectively, a first control device and a second control device. In other words, the first control device and the second control device manage the fluid flow within the siphon line and the connecting line, respectively.

[0024] According to one feature of the invention, the return line includes a control module. The control module manages the return of gas within the tank.

[0025] According to one feature of the invention, the pumping device and / or the compression device is configured to raise the gas pressure to a pressure between 1 and 8 bar relative, preferably between 1 and 5 bar relative. This pressure range allows the gas in its vapor state or the evaporated gas to meet the needs of the gas-consuming appliance.

[0026] According to one feature of the invention, the evaporation device is a heat exchanger configured to perform a heat exchange between the gas in its liquid state circulating in the first supply circuit and a third fluid. The third fluid can, for example, be glycol water or seawater. During the heat exchange taking place in the evaporation device, the third fluid heats the gas in its liquid state, which rises in temperature until it evaporates.

[0027] According to one feature of the invention, the feeding system comprises measuring means configured to be disposed in the tank, the measuring means being configured to measure a level of gas in the liquid state and / or a pressure internal to the tank, and communicate this measurement to a central unit of the power supply system. The measuring devices are arranged within the tank and allow monitoring of the remaining quantity of gas in its liquid state. Measuring this quantity is important because it allows determining if the pumping device is at risk of losing its prime and if this risk is imminent.

[0028] Both level and pressure measurements indicate the remaining quantity of liquid gas in the tank. Level measurement can be performed, for example, using a level sensor, radar, or a float. A low level of liquid gas remaining in the tank, for example, less than 2 m³ + / - 0.5 m³, means that the supply method must be changed to prevent the pumping device from losing its prime.

[0029] Significant variations in the liquid gas level over time can also be an indicator for switching to the second feeding mode. Indeed, these variations may be due to significant rolling, increasing the risk of the pumping device losing its prime.

[0030] The remaining quantity of gas can also be determined by pressure measurement, more specifically by measuring a pressure differential. For this purpose, a first pressure sensor is configured to measure the pressure at the bottom of the tank, that is, the pressure of all the gas contained in the tank, namely the gas in its liquid state and the gas in its vapor state present in the tank head. A second pressure sensor is configured to measure only the pressure of the gas in its vapor state present in the tank head. The pressure differential between these two pressure measurements allows the height of the gas in its liquid state in the tank to be deduced, and therefore the quantity of gas remaining in its liquid state in the tank.

[0031] Furthermore, pressure measurement is also important to determine whether a pressure increase via the return line is necessary to ensure the proper operation of the second feed mode. It has been determined that a pressure greater than or equal to 0.4 bar relative, for example 0.5 or 0.7 bar relative, is sufficient to implement the second feed mode without the need to increase the tank pressure by returning gas in the vapor state via the return line.

[0032] Of course, the maximum pressure within the tank must be controlled to prevent damage to the tank walls due to overpressure. Depending on the type of tank, the maximum pressure can be between 0.7 and 3 bar relative, for example 0.7, 1.6, or 2 bar relative.

[0033] Depending on the amount of gas remaining in the liquid state and / or the measured pressure, the central unit is able to analyze these measurements and change the supply mode of the supply system via a control instruction to a control means.

[0034] The invention also covers a method of supplying gas to at least one gas-consuming appliance of a floating structure comprising at least one tank, implemented by a gas supply system as described above, during which: - according to a first supply method, the gas-consuming appliance is supplied with gas via the first supply circuit in which gas is circulated in liquid state using the pumping device and / or the gas-consuming appliance is supplied with gas via the second supply circuit in which gas is circulated in vapor state using the compression device, - according to a second supply method, the gas-consuming appliance is supplied with gas via the first supply circuit, within which gas in liquid state is circulated using a pressure differential without the aid of the pumping device, and gas in vapor state is returned to the tank,

[0035] the choice of the supply method being dependent on information relating to the quantity of gas in liquid state contained in the tank.

[0036] The feeding method implements the structural and functional characteristics of the feeding system described above, combined with the implementation of the return line. Information regarding the quantity of gas in the liquid state contained in the tank is measured by the measuring means described above.

[0037] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples given in the accompanying schematic drawings on the other hand, in which:

[0038] [Fig-1] represents a gas supply system according to the invention,

[0039] [Fig.2] illustrates the power supply system of [Fig.1] operating according to a first power supply method,

[0040] [Fig.3] illustrates a first step in a transition from the first power supply mode illustrated in [Fig.2] to a second power supply mode,

[0041] [Fig.4] illustrates a second stage of a transition from the first power supply mode illustrated in [Fig.2] to the second power supply mode,

[0042] [Fig.5] illustrates a third stage of a transition from the first power supply mode illustrated in [Fig.2] to the second power supply mode.

[0043] Figure 1 schematically represents a gas supply system 1 according to the invention. The supply system 1 is, for example, integrated within a floating structure comprising a tank 2 ensuring the storage of said gas in liquid form and at least one gas-consuming appliance 3 that can be supplied with The gas contained in tank 2. In [Fig. 1] and the following figures, a first gas-consuming device 3a and a second gas-consuming device 3b are shown. The floating structure may, however, contain more gas-consuming devices 3, or only a single gas-consuming device 3. By way of example, the gas-consuming devices 3 may be an engine providing propulsion for the floating structure, a generator supplying the floating structure with electricity such as a fuel cell, a gas boiler, or a burner.

[0044] The supply system 1 comprises a first supply circuit 4 and a second supply circuit 5, each of which is suitable for supplying the gas-consuming devices 3. More specifically, the first supply circuit 4 is suitable for pumping gas in liquid form 6 contained in the tank 2 while the second supply circuit 5 is suitable for drawing gas in vapor form stagnant in the head 7 of the tank 2.

[0045] The first supply circuit 4 includes a pumping device 8 arranged at the bottom of the tank 2, which circulates the gas in its liquid state within the first supply circuit 4. The first supply circuit 4 also includes an evaporation device 9 through which the gas in its liquid state circulating in the first supply circuit 4 flows to be evaporated. The first supply circuit 4 then extends to the gas-consuming appliances 3.

[0046] The evaporation device 9, as illustrated in Figures 1 to 5, can, for example, be a heat exchanger configured to perform a heat exchange between the gas circulating in the first supply circuit 4 and a third fluid, which could be glycol water. The third fluid thus increases the temperature of the gas in its liquid state until it evaporates. Not shown, the evaporated gas exiting the evaporation device 9 can circulate within a heating device, which could also be a heat exchanger, in order to further increase the temperature of the evaporated gas so that it reaches a temperature compatible with the supply requirements of the gas-consuming appliances 3.

[0047] The second supply circuit 5 includes at least one compression device 10 for drawing in the gas in the vapor state stagnant in the head 7 of the tank 2 and raising it to a pressure compatible with the needs of the gas-consuming devices 3.

[0048] In the example illustrated in Figures 1 to 5, the power supply system 1 comprises a first compression device 10a and a second compression device 10b arranged in parallel with each other. The first compression device 10a is located on the second power supply circuit 5, while the second compression device 10b is located on an auxiliary line 11. connected to the second supply circuit 5. The presence of two compression devices 10 makes it possible in particular to ensure redundancy in order to cope with any malfunction, for example a failure, of one of the compressors 10.

[0049] As the liquid gas 6 contained in the tank 2 is pumped by the pumping device 8, the level of liquid gas 6 within the tank 2 decreases, and it can reach a critical level, particularly if the journey of the floating structure is long and without the possibility of refueling. This can cause a malfunction in the pumping device 8 if it emerges from the liquid gas 6 due to an insufficient remaining quantity or excessive rolling.

[0050] To enable the efficient supply of gas-consuming appliances, even in this critical level situation, the supply system 1 according to the invention comprises a junction line 12 extending between a first junction point 13 located on the first supply circuit 4 between the evaporation device 9 and the gas-consuming appliances 3 and a second junction point 14 located on the second supply circuit 5 located between the tank 2 and the compression devices 10, as well as a siphon line 15 connected to the first supply circuit 4 between the pumping device 8 and the evaporation device 9 and comprising an end 16 immersed in the tank 2. The end 16 of the siphon line is advantageously located at the bottom of the tank, for example at most 2m from the bottom of the tank 2.In this way, liquid gas can enter the siphon line 15 via this end 16 even when the pumping device, and in particular the liquid inlet orifice, is no longer immersed.

[0051] The junction line 12 fluidly connects the first supply circuit 4 to the second supply circuit 5, more particularly the evaporation device 9 to the compression devices 10.

[0052] Thus, in the event of a risk of the pumping device 8 activating, it can be stopped to prevent any malfunction. At least one of the compression devices 10 then allows the remaining liquid gas 6 in the tank 2 to be drawn off via the siphon line 15 and the connecting line 12, without the need to activate the pumping device. Indeed, the compression device 10 compresses the fluid, thus generating a pressure differential with a gas pressure upstream of the compression device 10 which is higher than a lower pressure upstream of the compression device 10, and therefore at the level of the evaporation device 9, which tends to facilitate the arrival of the liquid gas towards this evaporation device 9 via the siphon line 15. This then results in a circulation of the gas in the liquid state within the siphon line 15 without requiring the arrangement of a pumping device.The pumping device 8 can then be stopped. in order to avoid any risk of malfunction due to a low level of gas in liquid state 6, but the supply system 1 still ensures a supply to the gas-consuming devices 3, via the compression device 10 and the end of the second supply circuit 5.

[0053] The supply system 1 also includes a return line 17 connected to the second supply circuit 5 between the compression device 10 and the gas-consuming devices 3. The return line 17 allows gas in vapor form, compressed by the compression device 10, to be returned to the tank 2. This return of gas in vapor form to the tank 2 has the effect of increasing the pressure within the tank 2 and thus promoting the circulation of gas in liquid form within the siphon line 15. A portion of gas in liquid form is then pushed out of the tank 2, since the siphon line 15 is at that moment the only one open to discharge liquid gas.

[0054] It should be noted that the auxiliary line 11 is connected to the second supply circuit 5 between the second junction point 14 and a convergence point 18 located on the second supply circuit 5 between the first compression device 10a and the connection to the return line 17, so that all the functions of the supply system 1 are ensured regardless of which compression device 10 is used. Furthermore, the two compression devices 10a and 10b, although initially used to provide redundancy, can be used simultaneously to improve the pressure differential and further facilitate the flow of the gas in its liquid state in the siphon line 15.

[0055] The gas circulation in the first supply circuit 4 is placed under the control of a first control element 19 and a second control element 20. The first control element 19 is disposed on the first supply circuit 4 between the pumping device 8 and the connection with the siphon line 15, while the second control element 20 is disposed on the first supply circuit 4 between the first junction point 13 and the gas-consuming appliances 3. The first control element 19 and the second control element 20 can be valves capable of alternating between an open position and a closed position, respectively in order to allow or prohibit the circulation of fluid.

[0056] The second supply circuit 5 includes a control element 21 disposed between the tank 2 and the second junction point 14. The control element 21 allows or prohibits a fluid connection from the top 7 of the tank 2 to the compression devices 10.

[0057] The siphoning line 15 and the junction line 12 each comprise, respectively, a first control device 22 and a second device control 23 allowing to authorise or prohibit a circulation of fluid within the siphon line 15 or the junction line 12.

[0058] Finally, the return line 17 includes a control module 24 allowing the circulation of fluid within the return line 17 to be authorized or prohibited.

[0059] The supply system 1 also includes measuring means 25 configured to be arranged within the tank 2 or in contact with the tank 2 via a line fluidly connected to the tank, or at least to perform measurements within the tank 2. The measuring means 25 are specifically configured to determine the quantity of gas in the liquid state 6 remaining in the tank 2. Such monitoring of the remaining quantity of gas in the liquid state is particularly important since a malfunction in the pumping device 8 can occur due to a low remaining quantity.

[0060] In order to measure the remaining quantity of liquid gas 6 contained in the tank 2, the measuring means 25 can measure a level of liquid gas 6 contained in the tank 2. To measure the gas level, one of the measuring means 25 can, for example, be a level measuring sensor, a radar, or a float. A low level of the liquid gas remaining in the tank 2, for example, less than 2 m³ + / - 0.5 m³, means that there is a risk of malfunction of the pumping device 8.

[0061] The remaining quantity of gas in the liquid state in tank 2 can also be determined by pressure measurement, more particularly by measuring a pressure differential. For example, the measuring means 25 may include a first pressure sensor configured to measure the pressure at the bottom of the tank, and a second pressure sensor configured to measure only the pressure of the gas in the vapor state present in the headspace 7 of tank 2. The pressure differential between these two pressure measurements makes it possible to deduce the height of the gas in the liquid state in tank 2 and therefore the remaining quantity of gas in the liquid state in tank 2.

[0062] The pressure measurement by the measuring means 25 also makes it possible to determine whether a pressure increase via the return line 17 is necessary to ensure the proper functioning of the supply system 1. A pressure greater than or equal to 0.4 bar relative, for example 0.5 or 0.7 bar relative, within the tank 2 is sufficient to ensure the circulation of the gas in the liquid state. However, the pressure must not exceed a maximum pressure threshold to avoid damage to the walls of the tank 2. Depending on the type of tank, the maximum pressure can be between 0.7 and 3 bar relative, for example 0.7, 1.6, or 2 bar relative.

[0063] The measurement means 25 are thus configured to be able to transmit these measurements to a central unit, not shown, which will modify the configuration of the power supply system as a consequence of the measurements in relation to predetermined threshold values.

[0064] Figures 2 to 5 represent the supply system 1 according to the invention as just described, according to different supply methods for gas-consuming appliances. In Figures 2 to 5, the portions through which the gas flows are shown in solid lines and the portions without gas flow are shown in dashed lines.

[0065] In order to ensure the management of the gas supply, the supply system 1 allows the implementation of a gas supply process, which consists of determining and implementing a specific supply mode according to the quantity of liquid gas present in the tank, in order to optimize the supply of the gas-consuming devices 3. In [Fig.2], a first supply mode of the supply system 1 is represented.

[0066] According to the first supply method, the gas flows in liquid form in the first supply circuit 4 and in vapor form in the second supply circuit 5. In [Fig. 2], gas flows in both supply circuits 4 and 5, but depending on the amount of gas in vapor form present in the headspace 7 of the tank 2, it is possible that only one of the supply circuits 4 and 5 allows gas circulation. If there is sufficient gas in vapor form in the headspace 7 of the tank 2 to meet the supply requirements of the gas-consuming devices 3, then the second supply circuit 5 can be used alone. Conversely, if there is no gas in vapor form present in the headspace 7 of the tank 2, then the first supply circuit 4 can be used alone. In [Fig. 2], both supply circuits 4 and 5 are used simultaneously.

[0067] According to this first supply method, the liquid gas 6 contained in the tank 2 is pumped by the pumping device 8 to circulate in the first supply circuit 4. The liquid gas is then evaporated in the evaporation device 9, as the gas-consuming devices 3 can only be supplied with gas in the vapor state. The evaporated gas then circulates in the first supply circuit 4 until it supplies the gas-consuming devices 3. In this supply method, the first control element 19 and the second control element 20 are configured to allow, respectively, the passage of liquid gas upstream of the evaporation device 9 and evaporated gas downstream of the evaporation device 9.

[0068] The gas in vapor form present in the headspace 7 of the tank 2 is drawn in and compressed within the second supply circuit 5 by the compression device 10. In [Fig. 2], it is the first compression device 10a that compresses the gas in vapor form. The second compression device 10b can be used, for example, in the event of a failure of the first compression device 10a, the gas in vapor form then circulating within the auxiliary line 11. After being compressed, the gas in vapor form then supplies the gas-consuming devices 3. The compression of the gas into the vapor state is carried out so that the pressure of the gas in the vapor state at the outlet of the compression device 10. In this supply mode, the control element 21 is configured to respectively allow the passage of the gas in the vapor state upstream of the compression device 10.

[0069] This first supply mode is used when the measuring means 25 detect a quantity of gas in liquid state 6 sufficient to avoid generating any risk of creating a malfunction of the pumping device 8. In this embodiment, the first control device 22, the second control device 23 and the control module 24 are in the closed position.

[0070] When the measuring means 25 detect a lower quantity of gas in the liquid state to the point where there is an imminent risk of malfunction of the pumping device 8, a switch from the first supply mode to a second supply mode is then implemented to prevent this malfunction. Such detection may, for example, correspond to a level of gas in the liquid state below a level threshold, or to a differential pressure value measured above a pressure threshold.

[0071] The central unit can then consider this detection as revealing an imminent malfunction of the pumping device 8, and can then issue a command to change the power supply mode.

[0072] Fig. 3 illustrates a first step in the transition from the first power supply mode to the second power supply mode.

[0073] During this first transition step, the second control device 23 is opened to allow the evaporated gas to flow from the evaporation device 9 into the connecting line 12. Part of the evaporated gas then flows from the first supply circuit 4 to the second supply circuit 5 via the connecting line 12, drawn in by the compression device 10, while the remainder of the evaporated gas flowing in the first supply circuit 4 continues to supply the gas-consuming devices 3. This first step ensures fluid connection between the first supply circuit 4 and the second supply circuit 5 via the connecting line 12. This first step also initiates the pressure differential by lowering the pressure upstream of the compression device 10.

[0074] Figure 4 illustrates a second stage in the transition from the first power supply mode to the second power supply mode. This second stage occurs after the first stage illustrated in Figure 3. Therefore, the starting point of this second stage will be considered to be the configuration illustrated in Figure 3.

[0075] During the second stage, the control element 21 located on the second supply circuit 5 is closed. Thus, the gas compressed by the device compression 10 comes only from the first supply circuit 4, downstream of the evaporation device 9. In other words, the gas in vapor state present in the head 7 of the tank 2 is no longer evacuated.

[0076] In the example illustrated in [Fig. 4], the control module 24 is open so that some of the compressed gas flows through the return line 17 downstream of the compression device 10. Compressed gas in vapor form is thus partially returned to the tank 2 via the return line 17. Since the gas in vapor form is no longer discharged from the tank 2 and, moreover, the return line 17 ensures the return of gas in vapor form to the tank 2, the internal pressure of the latter begins to increase. This increase in the internal pressure of the tank 2 will subsequently facilitate the flow of gas in liquid form.

[0077] Figure 5 illustrates a third and final transitional stage towards the second supply mode. Therefore, [Fig. 5] also illustrates the gas flow when the second supply mode is implemented. This second supply mode, as previously mentioned, eliminates the need for the pumping device 8 to supply the gas-consuming appliances 3.

[0078] After the second step illustrated in [Fig.4], the third step consists of closing the first control member 19 and the second control member 20, while opening the first control device 22 to allow the flow of gas in the liquid state within the siphon line 15.

[0079] Closing the first control device 19 is accompanied by the shutdown of the pumping device 8 before any potential malfunction occurs. The siphon line 15 is then opened to allow the circulation of gas in a liquid state within it. Indeed, the compression device 10 generates the pressure differential between the evaporation device 9 and downstream of the compression device 10 within the first supply circuit 4. The pressure differential is reinforced by the pressure increase within the tank 2 due to the return of gas in a vapor state via the return line 17 into the tank 2.

[0080] The generated pressure differential allows the gas to circulate in the liquid state within the siphon line 15 and in the first supply circuit 4 without the need to implement the pumping device 8. The gas in the liquid state 6 contained in the tank 2 rushes into the siphon line 15 via the end 16 and joins the first supply circuit 4.

[0081] The gas in liquid state is then evaporated by the evaporation device 9 and circulates entirely within the junction line 12. The closure of the second control member 20 makes it possible to improve the suction capacity of the junction line 12 by pressure differential implemented in part by the compression device 10.

[0082] The evaporated gas thus joins the second supply circuit 5 via the junction line 12, is compressed by the compression device 10 and is finally supplied to the gas-consuming devices 3. It is possible to implement the two compression devices 10 simultaneously, in order to generate a pressure differential more easily and thus promote the circulation of gas in the liquid state within the siphon line 15.

[0083] Of course, the invention is not limited to the examples just described and many modifications can be made to these examples without departing from the scope of the invention.

[0084] The invention, as described above, achieves its intended purpose and provides a supply system capable of continuously supplying a gas-consuming appliance even if the bottom-of-tank pumping device is unusable or at risk of malfunction. Variations not described here could be implemented without departing from the scope of the invention, provided that, in accordance with the invention, they include a supply system conforming to the invention.

Claims

1. Demands Gas supply system (1) for at least one gas-consuming appliance (3, 3a, 3b) of a floating structure comprising at least one tank (2) configured to contain gas, the supply system (1) comprising: - at least one first supply circuit (4) configured to supply gas to the gas-consuming appliance (3, 3a, 3b), the first supply circuit (4) comprising at least one pumping device (8) configured to, in a first supply mode, draw the gas in liquid form from the tank (2) and at least one evaporation device (9) configured to evaporate the gas in liquid form circulating in the first supply circuit (4), - at least one second supply circuit (5) configured to supply gas to the gas-consuming appliance (3, 3a, 3b), the second supply circuit (5) comprising at least one compression device (10) configured to, in the first supply mode, draw gas in vapor form from the tank (2) and compress it to a pressure compatible with the needs of the gas-consuming appliance (3, 3a, 3b), characterized in that the supply system (1) comprises at least one connecting line (12) and at least one siphoning line (15), the connecting line (12) extending between a first junction point (13) disposed on the first supply circuit (4) between the evaporator (9) and the consuming appliance of gas (3, 3a, 3b) and a second junction point (14) disposed on the second supply circuit (5) between the tank (2) and the compression device (10), the siphon line (15) being connected to the first supply circuit (4) between the pumping device (8) and the evaporating device (9) and comprising an end (16) configured to be immersed in the tank (2), the compression device (10) being capable of, in a second supply mode, taking the gas in liquid form from the tank (2) via the siphon line (15) and the junction line (12).

2. Supply system (1) according to claim 1, comprising a return line (17) connected to the second supply circuit (5) between the compression device (10) and the gas-consuming device (3, 3a, 3b) and configured to extend to the tank (2), the return line (17) being capable of returning at least a portion of the gas in vapor form compressed by the compression device (10) into the tank (2).

3. Supply system (1) according to claim 1 or 2, wherein the compression device (10) is a first compression device (10a), the supply system (1) comprising an auxiliary line (11) and a second compression device (10b) disposed on the auxiliary line (11), said auxiliary line (11) extending between the second junction point (14) and a convergence point (18) disposed on the second supply circuit (5) between the first compression device (10a) and the gas-consuming device (3, 3a, 3b).

4. Power supply system (1) according to claim 3, combined with claim 2, wherein the convergence point (18) is disposed on the second power supply circuit (5) between the first compression circuit and the connection with the return line (17).

5. Supply system (1) according to any one of claims 1 to 4, wherein the first supply circuit (4) comprises a first control member (19) disposed between the pumping device (8) and the connection with the siphon line (15) and a second control member (20) disposed between the first junction point (13) and the gas-consuming appliance (3, 3a, 3b).

6. Feeding system (1) according to any one of claims 1 to 5, wherein the second feeding circuit (5) includes a control element (21) disposed between the tank (2) and the second junction point (14).

7. Feeding system (1) according to any one of claims 1 to 6, wherein the siphon line (15) and the junction line (12) comprise respectively a first control device (22) and a second control device (23).

8. Power supply system (1) according to any one of claims 2 to 6 in combination with claim 2, wherein the return line (17) comprises a control module (24).

9. Supply system (1) according to any one of claims 1 to 8, wherein the pumping device (8) and / or the compression device (10) is configured to raise the gas pressure to a pressure between 1 and 8 bar relative, preferably between 1 and 5 bar relative.

10. Feeding system (1) according to any one of claims 1 to 9, wherein the evaporation device (9) is a heat exchanger configured to perform heat exchange between the gas in the liquid state circulating in the first feed circuit (4) and a third fluid.

11. Feeding system (1) according to any one of claims 1 to 10, comprising measuring means (25) configured to be disposed in the tank (2), the measuring means (25) being configured to measure a level of gas in the liquid state and / or an internal pressure of the tank (2), and to communicate said measurement to a central unit of the feeding system (1).

12. A method for supplying gas to at least one gas-consuming appliance (3, 3a, 3b) of a floating structure comprising at least one tank (2), implemented by a gas supply system (1) according to any one of claims 2 to 11, in combination with claim 2, wherein: - according to a first supply method, the gas-consuming appliance (3, 3a, 3b) is supplied with gas via the first supply circuit (4) through which gas is circulated in liquid form using the pumping device (8) and / or the gas-consuming appliance (3, 3a, 3b) is supplied with gas via the second supply circuit (5) through which gas is circulated in vapor form using the compression device (10), - according to a second supply method, the gas-consuming appliance (3, 3a,3b) with the gas via the first supply circuit (4) in which gas in liquid state is circulated using a pressure differential without the aid of the pumping device (8), and gas in vapor state is returned to the tank (2), the choice of the supply method being dependent on information relating to the quantity of gas in liquid state contained in the tank (2).

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